1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
4
5 /* Copyright (c) University of Cambridge 1995 - 2018 */
6 /* Copyright (c) The Exim Maintainers 2020 */
7 /* See the file NOTICE for conditions of use and distribution. */
8
9 /* Functions for handling an incoming SMTP call. */
10
11
12 #include "exim.h"
13 #include <assert.h>
14
15
16 /* Initialize for TCP wrappers if so configured. It appears that the macro
17 HAVE_IPV6 is used in some versions of the tcpd.h header, so we unset it before
18 including that header, and restore its value afterwards. */
19
20 #ifdef USE_TCP_WRAPPERS
21
22 #if HAVE_IPV6
23 #define EXIM_HAVE_IPV6
24 #endif
25 #undef HAVE_IPV6
26 #include <tcpd.h>
27 #undef HAVE_IPV6
28 #ifdef EXIM_HAVE_IPV6
29 #define HAVE_IPV6 TRUE
30 #endif
31
32 int allow_severity = LOG_INFO;
33 int deny_severity = LOG_NOTICE;
34 uschar *tcp_wrappers_name;
35 #endif
36
37
38 /* Size of buffer for reading SMTP commands. We used to use 512, as defined
39 by RFC 821. However, RFC 1869 specifies that this must be increased for SMTP
40 commands that accept arguments, and this in particular applies to AUTH, where
41 the data can be quite long. More recently this value was 2048 in Exim;
42 however, RFC 4954 (circa 2007) recommends 12288 bytes to handle AUTH. Clients
43 such as Thunderbird will send an AUTH with an initial-response for GSSAPI.
44 The maximum size of a Kerberos ticket under Windows 2003 is 12000 bytes, and
45 we need room to handle large base64-encoded AUTHs for GSSAPI.
46 */
47
48 #define SMTP_CMD_BUFFER_SIZE 16384
49
50 /* Size of buffer for reading SMTP incoming packets */
51
52 #define IN_BUFFER_SIZE 8192
53
54 /* Structure for SMTP command list */
55
56 typedef struct {
57 const char *name;
58 int len;
59 short int cmd;
60 short int has_arg;
61 short int is_mail_cmd;
62 } smtp_cmd_list;
63
64 /* Codes for identifying commands. We order them so that those that come first
65 are those for which synchronization is always required. Checking this can help
66 block some spam. */
67
68 enum {
69 /* These commands are required to be synchronized, i.e. to be the last in a
70 block of commands when pipelining. */
71
72 HELO_CMD, EHLO_CMD, DATA_CMD, /* These are listed in the pipelining */
73 VRFY_CMD, EXPN_CMD, NOOP_CMD, /* RFC as requiring synchronization */
74 ETRN_CMD, /* This by analogy with TURN from the RFC */
75 STARTTLS_CMD, /* Required by the STARTTLS RFC */
76 TLS_AUTH_CMD, /* auto-command at start of SSL */
77
78 /* This is a dummy to identify the non-sync commands when pipelining */
79
80 NON_SYNC_CMD_PIPELINING,
81
82 /* These commands need not be synchronized when pipelining */
83
84 MAIL_CMD, RCPT_CMD, RSET_CMD,
85
86 /* This is a dummy to identify the non-sync commands when not pipelining */
87
88 NON_SYNC_CMD_NON_PIPELINING,
89
90 /* RFC3030 section 2: "After all MAIL and RCPT responses are collected and
91 processed the message is sent using a series of BDAT commands"
92 implies that BDAT should be synchronized. However, we see Google, at least,
93 sending MAIL,RCPT,BDAT-LAST in a single packet, clearly not waiting for
94 processing of the RCPT response(s). We shall do the same, and not require
95 synch for BDAT. Worse, as the chunk may (very likely will) follow the
96 command-header in the same packet we cannot do the usual "is there any
97 follow-on data after the command line" even for non-pipeline mode.
98 So we'll need an explicit check after reading the expected chunk amount
99 when non-pipe, before sending the ACK. */
100
101 BDAT_CMD,
102
103 /* I have been unable to find a statement about the use of pipelining
104 with AUTH, so to be on the safe side it is here, though I kind of feel
105 it should be up there with the synchronized commands. */
106
107 AUTH_CMD,
108
109 /* I'm not sure about these, but I don't think they matter. */
110
111 QUIT_CMD, HELP_CMD,
112
113 #ifdef SUPPORT_PROXY
114 PROXY_FAIL_IGNORE_CMD,
115 #endif
116
117 /* These are specials that don't correspond to actual commands */
118
119 EOF_CMD, OTHER_CMD, BADARG_CMD, BADCHAR_CMD, BADSYN_CMD,
120 TOO_MANY_NONMAIL_CMD };
121
122
123 /* This is a convenience macro for adding the identity of an SMTP command
124 to the circular buffer that holds a list of the last n received. */
125
126 #define HAD(n) \
127 smtp_connection_had[smtp_ch_index++] = n; \
128 if (smtp_ch_index >= SMTP_HBUFF_SIZE) smtp_ch_index = 0
129
130
131 /*************************************************
132 * Local static variables *
133 *************************************************/
134
135 static struct {
136 BOOL auth_advertised :1;
137 #ifndef DISABLE_TLS
138 BOOL tls_advertised :1;
139 #endif
140 BOOL dsn_advertised :1;
141 BOOL esmtp :1;
142 BOOL helo_verify_required :1;
143 BOOL helo_verify :1;
144 BOOL helo_seen :1;
145 BOOL helo_accept_junk :1;
146 #ifndef DISABLE_PIPE_CONNECT
147 BOOL pipe_connect_acceptable :1;
148 #endif
149 BOOL rcpt_smtp_response_same :1;
150 BOOL rcpt_in_progress :1;
151 BOOL smtp_exit_function_called :1;
152 #ifdef SUPPORT_I18N
153 BOOL smtputf8_advertised :1;
154 #endif
155 } fl = {
156 .helo_verify_required = FALSE,
157 .helo_verify = FALSE,
158 .smtp_exit_function_called = FALSE,
159 };
160
161 static auth_instance *authenticated_by;
162 static int count_nonmail;
163 static int nonmail_command_count;
164 static int synprot_error_count;
165 static int unknown_command_count;
166 static int sync_cmd_limit;
167 static int smtp_write_error = 0;
168
169 static uschar *rcpt_smtp_response;
170 static uschar *smtp_data_buffer;
171 static uschar *smtp_cmd_data;
172
173 /* We need to know the position of RSET, HELO, EHLO, AUTH, and STARTTLS. Their
174 final fields of all except AUTH are forced TRUE at the start of a new message
175 setup, to allow one of each between messages that is not counted as a nonmail
176 command. (In fact, only one of HELO/EHLO is not counted.) Also, we have to
177 allow a new EHLO after starting up TLS.
178
179 AUTH is "falsely" labelled as a mail command initially, so that it doesn't get
180 counted. However, the flag is changed when AUTH is received, so that multiple
181 failing AUTHs will eventually hit the limit. After a successful AUTH, another
182 AUTH is already forbidden. After a TLS session is started, AUTH's flag is again
183 forced TRUE, to allow for the re-authentication that can happen at that point.
184
185 QUIT is also "falsely" labelled as a mail command so that it doesn't up the
186 count of non-mail commands and possibly provoke an error.
187
188 tls_auth is a pseudo-command, never expected in input. It is activated
189 on TLS startup and looks for a tls authenticator. */
190
191 static smtp_cmd_list cmd_list[] = {
192 /* name len cmd has_arg is_mail_cmd */
193
194 { "rset", sizeof("rset")-1, RSET_CMD, FALSE, FALSE }, /* First */
195 { "helo", sizeof("helo")-1, HELO_CMD, TRUE, FALSE },
196 { "ehlo", sizeof("ehlo")-1, EHLO_CMD, TRUE, FALSE },
197 { "auth", sizeof("auth")-1, AUTH_CMD, TRUE, TRUE },
198 #ifndef DISABLE_TLS
199 { "starttls", sizeof("starttls")-1, STARTTLS_CMD, FALSE, FALSE },
200 { "tls_auth", 0, TLS_AUTH_CMD, FALSE, FALSE },
201 #endif
202
203 /* If you change anything above here, also fix the definitions below. */
204
205 { "mail from:", sizeof("mail from:")-1, MAIL_CMD, TRUE, TRUE },
206 { "rcpt to:", sizeof("rcpt to:")-1, RCPT_CMD, TRUE, TRUE },
207 { "data", sizeof("data")-1, DATA_CMD, FALSE, TRUE },
208 { "bdat", sizeof("bdat")-1, BDAT_CMD, TRUE, TRUE },
209 { "quit", sizeof("quit")-1, QUIT_CMD, FALSE, TRUE },
210 { "noop", sizeof("noop")-1, NOOP_CMD, TRUE, FALSE },
211 { "etrn", sizeof("etrn")-1, ETRN_CMD, TRUE, FALSE },
212 { "vrfy", sizeof("vrfy")-1, VRFY_CMD, TRUE, FALSE },
213 { "expn", sizeof("expn")-1, EXPN_CMD, TRUE, FALSE },
214 { "help", sizeof("help")-1, HELP_CMD, TRUE, FALSE }
215 };
216
217 static smtp_cmd_list *cmd_list_end =
218 cmd_list + sizeof(cmd_list)/sizeof(smtp_cmd_list);
219
220 #define CMD_LIST_RSET 0
221 #define CMD_LIST_HELO 1
222 #define CMD_LIST_EHLO 2
223 #define CMD_LIST_AUTH 3
224 #define CMD_LIST_STARTTLS 4
225 #define CMD_LIST_TLS_AUTH 5
226
227 /* This list of names is used for performing the smtp_no_mail logging action.
228 It must be kept in step with the SCH_xxx enumerations. */
229
230 uschar * smtp_names[] =
231 {
232 US"NONE", US"AUTH", US"DATA", US"BDAT", US"EHLO", US"ETRN", US"EXPN",
233 US"HELO", US"HELP", US"MAIL", US"NOOP", US"QUIT", US"RCPT", US"RSET",
234 US"STARTTLS", US"VRFY" };
235
236 static uschar *protocols_local[] = {
237 US"local-smtp", /* HELO */
238 US"local-smtps", /* The rare case EHLO->STARTTLS->HELO */
239 US"local-esmtp", /* EHLO */
240 US"local-esmtps", /* EHLO->STARTTLS->EHLO */
241 US"local-esmtpa", /* EHLO->AUTH */
242 US"local-esmtpsa" /* EHLO->STARTTLS->EHLO->AUTH */
243 };
244 static uschar *protocols[] = {
245 US"smtp", /* HELO */
246 US"smtps", /* The rare case EHLO->STARTTLS->HELO */
247 US"esmtp", /* EHLO */
248 US"esmtps", /* EHLO->STARTTLS->EHLO */
249 US"esmtpa", /* EHLO->AUTH */
250 US"esmtpsa" /* EHLO->STARTTLS->EHLO->AUTH */
251 };
252
253 #define pnormal 0
254 #define pextend 2
255 #define pcrpted 1 /* added to pextend or pnormal */
256 #define pauthed 2 /* added to pextend */
257
258 /* Sanity check and validate optional args to MAIL FROM: envelope */
259 enum {
260 ENV_MAIL_OPT_NULL,
261 ENV_MAIL_OPT_SIZE, ENV_MAIL_OPT_BODY, ENV_MAIL_OPT_AUTH,
262 #ifndef DISABLE_PRDR
263 ENV_MAIL_OPT_PRDR,
264 #endif
265 ENV_MAIL_OPT_RET, ENV_MAIL_OPT_ENVID,
266 #ifdef SUPPORT_I18N
267 ENV_MAIL_OPT_UTF8,
268 #endif
269 };
270 typedef struct {
271 uschar * name; /* option requested during MAIL cmd */
272 int value; /* enum type */
273 BOOL need_value; /* TRUE requires value (name=value pair format)
274 FALSE is a singleton */
275 } env_mail_type_t;
276 static env_mail_type_t env_mail_type_list[] = {
277 { US"SIZE", ENV_MAIL_OPT_SIZE, TRUE },
278 { US"BODY", ENV_MAIL_OPT_BODY, TRUE },
279 { US"AUTH", ENV_MAIL_OPT_AUTH, TRUE },
280 #ifndef DISABLE_PRDR
281 { US"PRDR", ENV_MAIL_OPT_PRDR, FALSE },
282 #endif
283 { US"RET", ENV_MAIL_OPT_RET, TRUE },
284 { US"ENVID", ENV_MAIL_OPT_ENVID, TRUE },
285 #ifdef SUPPORT_I18N
286 { US"SMTPUTF8",ENV_MAIL_OPT_UTF8, FALSE }, /* rfc6531 */
287 #endif
288 /* keep this the last entry */
289 { US"NULL", ENV_MAIL_OPT_NULL, FALSE },
290 };
291
292 /* When reading SMTP from a remote host, we have to use our own versions of the
293 C input-reading functions, in order to be able to flush the SMTP output only
294 when about to read more data from the socket. This is the only way to get
295 optimal performance when the client is using pipelining. Flushing for every
296 command causes a separate packet and reply packet each time; saving all the
297 responses up (when pipelining) combines them into one packet and one response.
298
299 For simplicity, these functions are used for *all* SMTP input, not only when
300 receiving over a socket. However, after setting up a secure socket (SSL), input
301 is read via the OpenSSL library, and another set of functions is used instead
302 (see tls.c).
303
304 These functions are set in the receive_getc etc. variables and called with the
305 same interface as the C functions. However, since there can only ever be
306 one incoming SMTP call, we just use a single buffer and flags. There is no need
307 to implement a complicated private FILE-like structure.*/
308
309 static uschar *smtp_inbuffer;
310 static uschar *smtp_inptr;
311 static uschar *smtp_inend;
312 static int smtp_had_eof;
313 static int smtp_had_error;
314
315
316 /* forward declarations */
317 static int smtp_read_command(BOOL check_sync, unsigned buffer_lim);
318 static int synprot_error(int type, int code, uschar *data, uschar *errmess);
319 static void smtp_quit_handler(uschar **, uschar **);
320 static void smtp_rset_handler(void);
321
322 /*************************************************
323 * Recheck synchronization *
324 *************************************************/
325
326 /* Synchronization checks can never be perfect because a packet may be on its
327 way but not arrived when the check is done. Normally, the checks happen when
328 commands are read: Exim ensures that there is no more input in the input buffer.
329 In normal cases, the response to the command will be fast, and there is no
330 further check.
331
332 However, for some commands an ACL is run, and that can include delays. In those
333 cases, it is useful to do another check on the input just before sending the
334 response. This also applies at the start of a connection. This function does
335 that check by means of the select() function, as long as the facility is not
336 disabled or inappropriate. A failure of select() is ignored.
337
338 When there is unwanted input, we read it so that it appears in the log of the
339 error.
340
341 Arguments: none
342 Returns: TRUE if all is well; FALSE if there is input pending
343 */
344
345 static BOOL
wouldblock_reading(void)346 wouldblock_reading(void)
347 {
348 int fd, rc;
349
350 #ifndef DISABLE_TLS
351 if (tls_in.active.sock >= 0)
352 return !tls_could_read();
353 #endif
354
355 if (smtp_inptr < smtp_inend)
356 return FALSE;
357
358 fd = fileno(smtp_in);
359 rc = poll_one_fd(fd, POLLIN, 0);
360
361 if (rc <= 0) return TRUE; /* Not ready to read */
362 rc = smtp_getc(GETC_BUFFER_UNLIMITED);
363 if (rc < 0) return TRUE; /* End of file or error */
364
365 smtp_ungetc(rc);
366 return FALSE;
367 }
368
369 static BOOL
check_sync(void)370 check_sync(void)
371 {
372 if (!smtp_enforce_sync || !sender_host_address || f.sender_host_notsocket)
373 return TRUE;
374
375 return wouldblock_reading();
376 }
377
378
379 /* If there's input waiting (and we're doing pipelineing) then we can pipeline
380 a reponse with the one following. */
381
382 static BOOL
pipeline_response(void)383 pipeline_response(void)
384 {
385 if ( !smtp_enforce_sync || !sender_host_address
386 || f.sender_host_notsocket || !f.smtp_in_pipelining_advertised)
387 return FALSE;
388
389 if (wouldblock_reading()) return FALSE;
390 f.smtp_in_pipelining_used = TRUE;
391 return TRUE;
392 }
393
394
395 #ifndef DISABLE_PIPE_CONNECT
396 static BOOL
pipeline_connect_sends(void)397 pipeline_connect_sends(void)
398 {
399 if (!sender_host_address || f.sender_host_notsocket || !fl.pipe_connect_acceptable)
400 return FALSE;
401
402 if (wouldblock_reading()) return FALSE;
403 f.smtp_in_early_pipe_used = TRUE;
404 return TRUE;
405 }
406 #endif
407
408 /*************************************************
409 * Log incomplete transactions *
410 *************************************************/
411
412 /* This function is called after a transaction has been aborted by RSET, QUIT,
413 connection drops or other errors. It logs the envelope information received
414 so far in order to preserve address verification attempts.
415
416 Argument: string to indicate what aborted the transaction
417 Returns: nothing
418 */
419
420 static void
incomplete_transaction_log(uschar * what)421 incomplete_transaction_log(uschar *what)
422 {
423 if (!sender_address /* No transaction in progress */
424 || !LOGGING(smtp_incomplete_transaction))
425 return;
426
427 /* Build list of recipients for logging */
428
429 if (recipients_count > 0)
430 {
431 raw_recipients = store_get(recipients_count * sizeof(uschar *), FALSE);
432 for (int i = 0; i < recipients_count; i++)
433 raw_recipients[i] = recipients_list[i].address;
434 raw_recipients_count = recipients_count;
435 }
436
437 log_write(L_smtp_incomplete_transaction, LOG_MAIN|LOG_SENDER|LOG_RECIPIENTS,
438 "%s incomplete transaction (%s)", host_and_ident(TRUE), what);
439 }
440
441
442
443
444 void
smtp_command_timeout_exit(void)445 smtp_command_timeout_exit(void)
446 {
447 log_write(L_lost_incoming_connection,
448 LOG_MAIN, "SMTP command timeout on%s connection from %s",
449 tls_in.active.sock >= 0 ? " TLS" : "", host_and_ident(FALSE));
450 if (smtp_batched_input)
451 moan_smtp_batch(NULL, "421 SMTP command timeout"); /* Does not return */
452 smtp_notquit_exit(US"command-timeout", US"421",
453 US"%s: SMTP command timeout - closing connection",
454 smtp_active_hostname);
455 exim_exit(EXIT_FAILURE);
456 }
457
458 void
smtp_command_sigterm_exit(void)459 smtp_command_sigterm_exit(void)
460 {
461 log_write(0, LOG_MAIN, "%s closed after SIGTERM", smtp_get_connection_info());
462 if (smtp_batched_input)
463 moan_smtp_batch(NULL, "421 SIGTERM received"); /* Does not return */
464 smtp_notquit_exit(US"signal-exit", US"421",
465 US"%s: Service not available - closing connection", smtp_active_hostname);
466 exim_exit(EXIT_FAILURE);
467 }
468
469 void
smtp_data_timeout_exit(void)470 smtp_data_timeout_exit(void)
471 {
472 log_write(L_lost_incoming_connection,
473 LOG_MAIN, "SMTP data timeout (message abandoned) on connection from %s F=<%s>",
474 sender_fullhost ? sender_fullhost : US"local process", sender_address);
475 receive_bomb_out(US"data-timeout", US"SMTP incoming data timeout");
476 /* Does not return */
477 }
478
479 void
smtp_data_sigint_exit(void)480 smtp_data_sigint_exit(void)
481 {
482 log_write(0, LOG_MAIN, "%s closed after %s",
483 smtp_get_connection_info(), had_data_sigint == SIGTERM ? "SIGTERM":"SIGINT");
484 receive_bomb_out(US"signal-exit",
485 US"Service not available - SIGTERM or SIGINT received");
486 /* Does not return */
487 }
488
489
490
491 /* Refill the buffer, and notify DKIM verification code.
492 Return false for error or EOF.
493 */
494
495 static BOOL
smtp_refill(unsigned lim)496 smtp_refill(unsigned lim)
497 {
498 int rc, save_errno;
499 if (!smtp_out) return FALSE;
500 fflush(smtp_out);
501 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
502
503 /* Limit amount read, so non-message data is not fed to DKIM.
504 Take care to not touch the safety NUL at the end of the buffer. */
505
506 rc = read(fileno(smtp_in), smtp_inbuffer, MIN(IN_BUFFER_SIZE-1, lim));
507 save_errno = errno;
508 if (smtp_receive_timeout > 0) ALARM_CLR(0);
509 if (rc <= 0)
510 {
511 /* Must put the error text in fixed store, because this might be during
512 header reading, where it releases unused store above the header. */
513 if (rc < 0)
514 {
515 if (had_command_timeout) /* set by signal handler */
516 smtp_command_timeout_exit(); /* does not return */
517 if (had_command_sigterm)
518 smtp_command_sigterm_exit();
519 if (had_data_timeout)
520 smtp_data_timeout_exit();
521 if (had_data_sigint)
522 smtp_data_sigint_exit();
523
524 smtp_had_error = save_errno;
525 smtp_read_error = string_copy_perm(
526 string_sprintf(" (error: %s)", strerror(save_errno)), FALSE);
527 }
528 else
529 smtp_had_eof = 1;
530 return FALSE;
531 }
532 #ifndef DISABLE_DKIM
533 dkim_exim_verify_feed(smtp_inbuffer, rc);
534 #endif
535 smtp_inend = smtp_inbuffer + rc;
536 smtp_inptr = smtp_inbuffer;
537 return TRUE;
538 }
539
540 /*************************************************
541 * SMTP version of getc() *
542 *************************************************/
543
544 /* This gets the next byte from the SMTP input buffer. If the buffer is empty,
545 it flushes the output, and refills the buffer, with a timeout. The signal
546 handler is set appropriately by the calling function. This function is not used
547 after a connection has negotiated itself into an TLS/SSL state.
548
549 Arguments: lim Maximum amount to read/buffer
550 Returns: the next character or EOF
551 */
552
553 int
smtp_getc(unsigned lim)554 smtp_getc(unsigned lim)
555 {
556 if (smtp_inptr >= smtp_inend)
557 if (!smtp_refill(lim))
558 return EOF;
559 return *smtp_inptr++;
560 }
561
562 BOOL
smtp_hasc(void)563 smtp_hasc(void)
564 {
565 return smtp_inptr < smtp_inend;
566 }
567
568 uschar *
smtp_getbuf(unsigned * len)569 smtp_getbuf(unsigned * len)
570 {
571 unsigned size;
572 uschar * buf;
573
574 if (smtp_inptr >= smtp_inend)
575 if (!smtp_refill(*len))
576 { *len = 0; return NULL; }
577
578 if ((size = smtp_inend - smtp_inptr) > *len) size = *len;
579 buf = smtp_inptr;
580 smtp_inptr += size;
581 *len = size;
582 return buf;
583 }
584
585 void
smtp_get_cache(unsigned lim)586 smtp_get_cache(unsigned lim)
587 {
588 #ifndef DISABLE_DKIM
589 int n = smtp_inend - smtp_inptr;
590 if (n > lim)
591 n = lim;
592 if (n > 0)
593 dkim_exim_verify_feed(smtp_inptr, n);
594 #endif
595 }
596
597
598 /* Forward declarations */
599 static inline void bdat_push_receive_functions(void);
600 static inline void bdat_pop_receive_functions(void);
601
602
603 /* Get a byte from the smtp input, in CHUNKING mode. Handle ack of the
604 previous BDAT chunk and getting new ones when we run out. Uses the
605 underlying smtp_getc or tls_getc both for that and for getting the
606 (buffered) data byte. EOD signals (an expected) no further data.
607 ERR signals a protocol error, and EOF a closed input stream.
608
609 Called from read_bdat_smtp() in receive.c for the message body, but also
610 by the headers read loop in receive_msg(); manipulates chunking_state
611 to handle the BDAT command/response.
612 Placed here due to the correlation with the above smtp_getc(), which it wraps,
613 and also by the need to do smtp command/response handling.
614
615 Arguments: lim (ignored)
616 Returns: the next character or ERR, EOD or EOF
617 */
618
619 int
bdat_getc(unsigned lim)620 bdat_getc(unsigned lim)
621 {
622 uschar * user_msg = NULL;
623 uschar * log_msg;
624
625 for(;;)
626 {
627 #ifndef DISABLE_DKIM
628 unsigned dkim_save;
629 #endif
630
631 if (chunking_data_left > 0)
632 return lwr_receive_getc(chunking_data_left--);
633
634 bdat_pop_receive_functions();
635 #ifndef DISABLE_DKIM
636 dkim_save = dkim_collect_input;
637 dkim_collect_input = 0;
638 #endif
639
640 /* Unless PIPELINING was offered, there should be no next command
641 until after we ack that chunk */
642
643 if (!f.smtp_in_pipelining_advertised && !check_sync())
644 {
645 unsigned n = smtp_inend - smtp_inptr;
646 if (n > 32) n = 32;
647
648 incomplete_transaction_log(US"sync failure");
649 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP protocol synchronization error "
650 "(next input sent too soon: pipelining was not advertised): "
651 "rejected \"%s\" %s next input=\"%s\"%s",
652 smtp_cmd_buffer, host_and_ident(TRUE),
653 string_printing(string_copyn(smtp_inptr, n)),
654 smtp_inend - smtp_inptr > n ? "..." : "");
655 (void) synprot_error(L_smtp_protocol_error, 554, NULL,
656 US"SMTP synchronization error");
657 goto repeat_until_rset;
658 }
659
660 /* If not the last, ack the received chunk. The last response is delayed
661 until after the data ACL decides on it */
662
663 if (chunking_state == CHUNKING_LAST)
664 {
665 #ifndef DISABLE_DKIM
666 dkim_collect_input = dkim_save;
667 dkim_exim_verify_feed(NULL, 0); /* notify EOD */
668 dkim_collect_input = 0;
669 #endif
670 return EOD;
671 }
672
673 smtp_printf("250 %u byte chunk received\r\n", FALSE, chunking_datasize);
674 chunking_state = CHUNKING_OFFERED;
675 DEBUG(D_receive) debug_printf("chunking state %d\n", (int)chunking_state);
676
677 /* Expect another BDAT cmd from input. RFC 3030 says nothing about
678 QUIT, RSET or NOOP but handling them seems obvious */
679
680 next_cmd:
681 switch(smtp_read_command(TRUE, 1))
682 {
683 default:
684 (void) synprot_error(L_smtp_protocol_error, 503, NULL,
685 US"only BDAT permissible after non-LAST BDAT");
686
687 repeat_until_rset:
688 switch(smtp_read_command(TRUE, 1))
689 {
690 case QUIT_CMD: smtp_quit_handler(&user_msg, &log_msg); /*FALLTHROUGH */
691 case EOF_CMD: return EOF;
692 case RSET_CMD: smtp_rset_handler(); return ERR;
693 default: if (synprot_error(L_smtp_protocol_error, 503, NULL,
694 US"only RSET accepted now") > 0)
695 return EOF;
696 goto repeat_until_rset;
697 }
698
699 case QUIT_CMD:
700 smtp_quit_handler(&user_msg, &log_msg);
701 /*FALLTHROUGH*/
702 case EOF_CMD:
703 return EOF;
704
705 case RSET_CMD:
706 smtp_rset_handler();
707 return ERR;
708
709 case NOOP_CMD:
710 HAD(SCH_NOOP);
711 smtp_printf("250 OK\r\n", FALSE);
712 goto next_cmd;
713
714 case BDAT_CMD:
715 {
716 int n;
717
718 if (sscanf(CS smtp_cmd_data, "%u %n", &chunking_datasize, &n) < 1)
719 {
720 (void) synprot_error(L_smtp_protocol_error, 501, NULL,
721 US"missing size for BDAT command");
722 return ERR;
723 }
724 chunking_state = strcmpic(smtp_cmd_data+n, US"LAST") == 0
725 ? CHUNKING_LAST : CHUNKING_ACTIVE;
726 chunking_data_left = chunking_datasize;
727 DEBUG(D_receive) debug_printf("chunking state %d, %d bytes\n",
728 (int)chunking_state, chunking_data_left);
729
730 if (chunking_datasize == 0)
731 if (chunking_state == CHUNKING_LAST)
732 return EOD;
733 else
734 {
735 (void) synprot_error(L_smtp_protocol_error, 504, NULL,
736 US"zero size for BDAT command");
737 goto repeat_until_rset;
738 }
739
740 bdat_push_receive_functions();
741 #ifndef DISABLE_DKIM
742 dkim_collect_input = dkim_save;
743 #endif
744 break; /* to top of main loop */
745 }
746 }
747 }
748 }
749
750 BOOL
bdat_hasc(void)751 bdat_hasc(void)
752 {
753 if (chunking_data_left > 0)
754 return lwr_receive_hasc();
755 return TRUE;
756 }
757
758 uschar *
bdat_getbuf(unsigned * len)759 bdat_getbuf(unsigned * len)
760 {
761 uschar * buf;
762
763 if (chunking_data_left <= 0)
764 { *len = 0; return NULL; }
765
766 if (*len > chunking_data_left) *len = chunking_data_left;
767 buf = lwr_receive_getbuf(len); /* Either smtp_getbuf or tls_getbuf */
768 chunking_data_left -= *len;
769 return buf;
770 }
771
772 void
bdat_flush_data(void)773 bdat_flush_data(void)
774 {
775 while (chunking_data_left)
776 {
777 unsigned n = chunking_data_left;
778 if (!bdat_getbuf(&n)) break;
779 }
780
781 bdat_pop_receive_functions();
782
783 if (chunking_state != CHUNKING_LAST)
784 {
785 chunking_state = CHUNKING_OFFERED;
786 DEBUG(D_receive) debug_printf("chunking state %d\n", (int)chunking_state);
787 }
788 }
789
790
791 static inline void
bdat_push_receive_functions(void)792 bdat_push_receive_functions(void)
793 {
794 /* push the current receive_* function on the "stack", and
795 replace them by bdat_getc(), which in turn will use the lwr_receive_*
796 functions to do the dirty work. */
797 if (!lwr_receive_getc)
798 {
799 lwr_receive_getc = receive_getc;
800 lwr_receive_getbuf = receive_getbuf;
801 lwr_receive_hasc = receive_hasc;
802 lwr_receive_ungetc = receive_ungetc;
803 }
804 else
805 {
806 DEBUG(D_receive) debug_printf("chunking double-push receive functions\n");
807 }
808
809 receive_getc = bdat_getc;
810 receive_getbuf = bdat_getbuf;
811 receive_hasc = bdat_hasc;
812 receive_ungetc = bdat_ungetc;
813 }
814
815 static inline void
bdat_pop_receive_functions(void)816 bdat_pop_receive_functions(void)
817 {
818 if (!lwr_receive_getc)
819 {
820 DEBUG(D_receive) debug_printf("chunking double-pop receive functions\n");
821 return;
822 }
823 receive_getc = lwr_receive_getc;
824 receive_getbuf = lwr_receive_getbuf;
825 receive_hasc = lwr_receive_hasc;
826 receive_ungetc = lwr_receive_ungetc;
827
828 lwr_receive_getc = NULL;
829 lwr_receive_getbuf = NULL;
830 lwr_receive_hasc = NULL;
831 lwr_receive_ungetc = NULL;
832 }
833
834 /*************************************************
835 * SMTP version of ungetc() *
836 *************************************************/
837
838 /* Puts a character back in the input buffer. Only ever
839 called once.
840
841 Arguments:
842 ch the character
843
844 Returns: the character
845 */
846
847 int
smtp_ungetc(int ch)848 smtp_ungetc(int ch)
849 {
850 if (smtp_inptr <= smtp_inbuffer)
851 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "buffer underflow in smtp_ungetc");
852
853 *--smtp_inptr = ch;
854 return ch;
855 }
856
857
858 int
bdat_ungetc(int ch)859 bdat_ungetc(int ch)
860 {
861 chunking_data_left++;
862 bdat_push_receive_functions(); /* we're not done yet, calling push is safe, because it checks the state before pushing anything */
863 return lwr_receive_ungetc(ch);
864 }
865
866
867
868 /*************************************************
869 * SMTP version of feof() *
870 *************************************************/
871
872 /* Tests for a previous EOF
873
874 Arguments: none
875 Returns: non-zero if the eof flag is set
876 */
877
878 int
smtp_feof(void)879 smtp_feof(void)
880 {
881 return smtp_had_eof;
882 }
883
884
885
886
887 /*************************************************
888 * SMTP version of ferror() *
889 *************************************************/
890
891 /* Tests for a previous read error, and returns with errno
892 restored to what it was when the error was detected.
893
894 Arguments: none
895 Returns: non-zero if the error flag is set
896 */
897
898 int
smtp_ferror(void)899 smtp_ferror(void)
900 {
901 errno = smtp_had_error;
902 return smtp_had_error;
903 }
904
905
906
907 /*************************************************
908 * Test for characters in the SMTP buffer *
909 *************************************************/
910
911 /* Used at the end of a message
912
913 Arguments: none
914 Returns: TRUE/FALSE
915 */
916
917 BOOL
smtp_buffered(void)918 smtp_buffered(void)
919 {
920 return smtp_inptr < smtp_inend;
921 }
922
923
924
925 /*************************************************
926 * Write formatted string to SMTP channel *
927 *************************************************/
928
929 /* This is a separate function so that we don't have to repeat everything for
930 TLS support or debugging. It is global so that the daemon and the
931 authentication functions can use it. It does not return any error indication,
932 because major problems such as dropped connections won't show up till an output
933 flush for non-TLS connections. The smtp_fflush() function is available for
934 checking that: for convenience, TLS output errors are remembered here so that
935 they are also picked up later by smtp_fflush().
936
937 This function is exposed to the local_scan API; do not change the signature.
938
939 Arguments:
940 format format string
941 more further data expected
942 ... optional arguments
943
944 Returns: nothing
945 */
946
947 void
smtp_printf(const char * format,BOOL more,...)948 smtp_printf(const char *format, BOOL more, ...)
949 {
950 va_list ap;
951
952 va_start(ap, more);
953 smtp_vprintf(format, more, ap);
954 va_end(ap);
955 }
956
957 /* This is split off so that verify.c:respond_printf() can, in effect, call
958 smtp_printf(), bearing in mind that in C a vararg function can't directly
959 call another vararg function, only a function which accepts a va_list.
960
961 This function is exposed to the local_scan API; do not change the signature.
962 */
963 /*XXX consider passing caller-info in, for string_vformat-onward */
964
965 void
smtp_vprintf(const char * format,BOOL more,va_list ap)966 smtp_vprintf(const char *format, BOOL more, va_list ap)
967 {
968 gstring gs = { .size = big_buffer_size, .ptr = 0, .s = big_buffer };
969 BOOL yield;
970
971 /* Use taint-unchecked routines for writing into big_buffer, trusting
972 that we'll never expand it. */
973
974 yield = !! string_vformat(&gs, SVFMT_TAINT_NOCHK, format, ap);
975 string_from_gstring(&gs);
976
977 DEBUG(D_receive)
978 {
979 uschar *msg_copy, *cr, *end;
980 msg_copy = string_copy(gs.s);
981 end = msg_copy + gs.ptr;
982 while ((cr = Ustrchr(msg_copy, '\r')) != NULL) /* lose CRs */
983 memmove(cr, cr + 1, (end--) - cr);
984 debug_printf("SMTP>> %s", msg_copy);
985 }
986
987 if (!yield)
988 {
989 log_write(0, LOG_MAIN|LOG_PANIC, "string too large in smtp_printf()");
990 smtp_closedown(US"Unexpected error");
991 exim_exit(EXIT_FAILURE);
992 }
993
994 /* If this is the first output for a (non-batch) RCPT command, see if all RCPTs
995 have had the same. Note: this code is also present in smtp_respond(). It would
996 be tidier to have it only in one place, but when it was added, it was easier to
997 do it that way, so as not to have to mess with the code for the RCPT command,
998 which sometimes uses smtp_printf() and sometimes smtp_respond(). */
999
1000 if (fl.rcpt_in_progress)
1001 {
1002 if (rcpt_smtp_response == NULL)
1003 rcpt_smtp_response = string_copy(big_buffer);
1004 else if (fl.rcpt_smtp_response_same &&
1005 Ustrcmp(rcpt_smtp_response, big_buffer) != 0)
1006 fl.rcpt_smtp_response_same = FALSE;
1007 fl.rcpt_in_progress = FALSE;
1008 }
1009
1010 /* Now write the string */
1011
1012 if (
1013 #ifndef DISABLE_TLS
1014 tls_in.active.sock >= 0 ? (tls_write(NULL, gs.s, gs.ptr, more) < 0) :
1015 #endif
1016 (fwrite(gs.s, gs.ptr, 1, smtp_out) == 0)
1017 )
1018 smtp_write_error = -1;
1019 }
1020
1021
1022
1023 /*************************************************
1024 * Flush SMTP out and check for error *
1025 *************************************************/
1026
1027 /* This function isn't currently used within Exim (it detects errors when it
1028 tries to read the next SMTP input), but is available for use in local_scan().
1029 It flushes the output and checks for errors.
1030
1031 Arguments: none
1032 Returns: 0 for no error; -1 after an error
1033 */
1034
1035 int
smtp_fflush(void)1036 smtp_fflush(void)
1037 {
1038 if (tls_in.active.sock < 0 && fflush(smtp_out) != 0) smtp_write_error = -1;
1039
1040 if (
1041 #ifndef DISABLE_TLS
1042 tls_in.active.sock >= 0 ? (tls_write(NULL, NULL, 0, FALSE) < 0) :
1043 #endif
1044 (fflush(smtp_out) != 0)
1045 )
1046 smtp_write_error = -1;
1047
1048 return smtp_write_error;
1049 }
1050
1051
1052
1053 /*************************************************
1054 * SMTP command read timeout *
1055 *************************************************/
1056
1057 /* Signal handler for timing out incoming SMTP commands. This attempts to
1058 finish off tidily.
1059
1060 Argument: signal number (SIGALRM)
1061 Returns: nothing
1062 */
1063
1064 static void
command_timeout_handler(int sig)1065 command_timeout_handler(int sig)
1066 {
1067 had_command_timeout = sig;
1068 }
1069
1070
1071
1072 /*************************************************
1073 * SIGTERM received *
1074 *************************************************/
1075
1076 /* Signal handler for handling SIGTERM. Again, try to finish tidily.
1077
1078 Argument: signal number (SIGTERM)
1079 Returns: nothing
1080 */
1081
1082 static void
command_sigterm_handler(int sig)1083 command_sigterm_handler(int sig)
1084 {
1085 had_command_sigterm = sig;
1086 }
1087
1088
1089
1090
1091 #ifdef SUPPORT_PROXY
1092 /*************************************************
1093 * Check if host is required proxy host *
1094 *************************************************/
1095 /* The function determines if inbound host will be a regular smtp host
1096 or if it is configured that it must use Proxy Protocol. A local
1097 connection cannot.
1098
1099 Arguments: none
1100 Returns: bool
1101 */
1102
1103 static BOOL
check_proxy_protocol_host()1104 check_proxy_protocol_host()
1105 {
1106 int rc;
1107
1108 if ( sender_host_address
1109 && (rc = verify_check_this_host(CUSS &hosts_proxy, NULL, NULL,
1110 sender_host_address, NULL)) == OK)
1111 {
1112 DEBUG(D_receive)
1113 debug_printf("Detected proxy protocol configured host\n");
1114 proxy_session = TRUE;
1115 }
1116 return proxy_session;
1117 }
1118
1119
1120 /*************************************************
1121 * Read data until newline or end of buffer *
1122 *************************************************/
1123 /* While SMTP is server-speaks-first, TLS is client-speaks-first, so we can't
1124 read an entire buffer and assume there will be nothing past a proxy protocol
1125 header. Our approach normally is to use stdio, but again that relies upon
1126 "STARTTLS\r\n" and a server response before the client starts TLS handshake, or
1127 reading _nothing_ before client TLS handshake. So we don't want to use the
1128 usual buffering reads which may read enough to block TLS starting.
1129
1130 So unfortunately we're down to "read one byte at a time, with a syscall each,
1131 and expect a little overhead", for all proxy-opened connections which are v1,
1132 just to handle the TLS-on-connect case. Since SSL functions wrap the
1133 underlying fd, we can't assume that we can feed them any already-read content.
1134
1135 We need to know where to read to, the max capacity, and we'll read until we
1136 get a CR and one more character. Let the caller scream if it's CR+!LF.
1137
1138 Return the amount read.
1139 */
1140
1141 static int
swallow_until_crlf(int fd,uschar * base,int already,int capacity)1142 swallow_until_crlf(int fd, uschar *base, int already, int capacity)
1143 {
1144 uschar *to = base + already;
1145 uschar *cr;
1146 int have = 0;
1147 int ret;
1148 int last = 0;
1149
1150 /* For "PROXY UNKNOWN\r\n" we, at time of writing, expect to have read
1151 up through the \r; for the _normal_ case, we haven't yet seen the \r. */
1152
1153 cr = memchr(base, '\r', already);
1154 if (cr != NULL)
1155 {
1156 if ((cr - base) < already - 1)
1157 {
1158 /* \r and presumed \n already within what we have; probably not
1159 actually proxy protocol, but abort cleanly. */
1160 return 0;
1161 }
1162 /* \r is last character read, just need one more. */
1163 last = 1;
1164 }
1165
1166 while (capacity > 0)
1167 {
1168 do { ret = read(fd, to, 1); } while (ret == -1 && errno == EINTR && !had_command_timeout);
1169 if (ret == -1)
1170 return -1;
1171 have++;
1172 if (last)
1173 return have;
1174 if (*to == '\r')
1175 last = 1;
1176 capacity--;
1177 to++;
1178 }
1179
1180 /* reached end without having room for a final newline, abort */
1181 errno = EOVERFLOW;
1182 return -1;
1183 }
1184
1185 /*************************************************
1186 * Setup host for proxy protocol *
1187 *************************************************/
1188 /* The function configures the connection based on a header from the
1189 inbound host to use Proxy Protocol. The specification is very exact
1190 so exit with an error if do not find the exact required pieces. This
1191 includes an incorrect number of spaces separating args.
1192
1193 Arguments: none
1194 Returns: Boolean success
1195 */
1196
1197 static void
setup_proxy_protocol_host()1198 setup_proxy_protocol_host()
1199 {
1200 union {
1201 struct {
1202 uschar line[108];
1203 } v1;
1204 struct {
1205 uschar sig[12];
1206 uint8_t ver_cmd;
1207 uint8_t fam;
1208 uint16_t len;
1209 union {
1210 struct { /* TCP/UDP over IPv4, len = 12 */
1211 uint32_t src_addr;
1212 uint32_t dst_addr;
1213 uint16_t src_port;
1214 uint16_t dst_port;
1215 } ip4;
1216 struct { /* TCP/UDP over IPv6, len = 36 */
1217 uint8_t src_addr[16];
1218 uint8_t dst_addr[16];
1219 uint16_t src_port;
1220 uint16_t dst_port;
1221 } ip6;
1222 struct { /* AF_UNIX sockets, len = 216 */
1223 uschar src_addr[108];
1224 uschar dst_addr[108];
1225 } unx;
1226 } addr;
1227 } v2;
1228 } hdr;
1229
1230 /* Temp variables used in PPv2 address:port parsing */
1231 uint16_t tmpport;
1232 char tmpip[INET_ADDRSTRLEN];
1233 struct sockaddr_in tmpaddr;
1234 char tmpip6[INET6_ADDRSTRLEN];
1235 struct sockaddr_in6 tmpaddr6;
1236
1237 /* We can't read "all data until end" because while SMTP is
1238 server-speaks-first, the TLS handshake is client-speaks-first, so for
1239 TLS-on-connect ports the proxy protocol header will usually be immediately
1240 followed by a TLS handshake, and with N TLS libraries, we can't reliably
1241 reinject data for reading by those. So instead we first read "enough to be
1242 safely read within the header, and figure out how much more to read".
1243 For v1 we will later read to the end-of-line, for v2 we will read based upon
1244 the stated length.
1245
1246 The v2 sig is 12 octets, and another 4 gets us the length, so we know how much
1247 data is needed total. For v1, where the line looks like:
1248 PROXY TCPn L3src L3dest SrcPort DestPort \r\n
1249
1250 However, for v1 there's also `PROXY UNKNOWN\r\n` which is only 15 octets.
1251 We seem to support that. So, if we read 14 octets then we can tell if we're
1252 v2 or v1. If we're v1, we can continue reading as normal.
1253
1254 If we're v2, we can't slurp up the entire header. We need the length in the
1255 15th & 16th octets, then to read everything after that.
1256
1257 So to safely handle v1 and v2, with client-sent-first supported correctly,
1258 we have to do a minimum of 3 read calls, not 1. Eww.
1259 */
1260
1261 #define PROXY_INITIAL_READ 14
1262 #define PROXY_V2_HEADER_SIZE 16
1263 #if PROXY_INITIAL_READ > PROXY_V2_HEADER_SIZE
1264 # error Code bug in sizes of data to read for proxy usage
1265 #endif
1266
1267 int get_ok = 0;
1268 int size, ret;
1269 int fd = fileno(smtp_in);
1270 const char v2sig[12] = "\x0D\x0A\x0D\x0A\x00\x0D\x0A\x51\x55\x49\x54\x0A";
1271 uschar * iptype; /* To display debug info */
1272 socklen_t vslen = sizeof(struct timeval);
1273 BOOL yield = FALSE;
1274
1275 os_non_restarting_signal(SIGALRM, command_timeout_handler);
1276 ALARM(proxy_protocol_timeout);
1277
1278 do
1279 {
1280 /* The inbound host was declared to be a Proxy Protocol host, so
1281 don't do a PEEK into the data, actually slurp up enough to be
1282 "safe". Can't take it all because TLS-on-connect clients follow
1283 immediately with TLS handshake. */
1284 ret = read(fd, &hdr, PROXY_INITIAL_READ);
1285 }
1286 while (ret == -1 && errno == EINTR && !had_command_timeout);
1287
1288 if (ret == -1)
1289 goto proxyfail;
1290
1291 /* For v2, handle reading the length, and then the rest. */
1292 if ((ret == PROXY_INITIAL_READ) && (memcmp(&hdr.v2, v2sig, sizeof(v2sig)) == 0))
1293 {
1294 int retmore;
1295 uint8_t ver;
1296
1297 /* First get the length fields. */
1298 do
1299 {
1300 retmore = read(fd, (uschar*)&hdr + ret, PROXY_V2_HEADER_SIZE - PROXY_INITIAL_READ);
1301 } while (retmore == -1 && errno == EINTR && !had_command_timeout);
1302 if (retmore == -1)
1303 goto proxyfail;
1304 ret += retmore;
1305
1306 ver = (hdr.v2.ver_cmd & 0xf0) >> 4;
1307
1308 /* May 2014: haproxy combined the version and command into one byte to
1309 allow two full bytes for the length field in order to proxy SSL
1310 connections. SSL Proxy is not supported in this version of Exim, but
1311 must still separate values here. */
1312
1313 if (ver != 0x02)
1314 {
1315 DEBUG(D_receive) debug_printf("Invalid Proxy Protocol version: %d\n", ver);
1316 goto proxyfail;
1317 }
1318
1319 /* The v2 header will always be 16 bytes per the spec. */
1320 size = 16 + ntohs(hdr.v2.len);
1321 DEBUG(D_receive) debug_printf("Detected PROXYv2 header, size %d (limit %d)\n",
1322 size, (int)sizeof(hdr));
1323
1324 /* We should now have 16 octets (PROXY_V2_HEADER_SIZE), and we know the total
1325 amount that we need. Double-check that the size is not unreasonable, then
1326 get the rest. */
1327 if (size > sizeof(hdr))
1328 {
1329 DEBUG(D_receive) debug_printf("PROXYv2 header size unreasonably large; security attack?\n");
1330 goto proxyfail;
1331 }
1332
1333 do
1334 {
1335 do
1336 {
1337 retmore = read(fd, (uschar*)&hdr + ret, size-ret);
1338 } while (retmore == -1 && errno == EINTR && !had_command_timeout);
1339 if (retmore == -1)
1340 goto proxyfail;
1341 ret += retmore;
1342 DEBUG(D_receive) debug_printf("PROXYv2: have %d/%d required octets\n", ret, size);
1343 } while (ret < size);
1344
1345 } /* end scope for getting rest of data for v2 */
1346
1347 /* At this point: if PROXYv2, we've read the exact size required for all data;
1348 if PROXYv1 then we've read "less than required for any valid line" and should
1349 read the rest". */
1350
1351 if (ret >= 16 && memcmp(&hdr.v2, v2sig, 12) == 0)
1352 {
1353 uint8_t cmd = (hdr.v2.ver_cmd & 0x0f);
1354
1355 switch (cmd)
1356 {
1357 case 0x01: /* PROXY command */
1358 switch (hdr.v2.fam)
1359 {
1360 case 0x11: /* TCPv4 address type */
1361 iptype = US"IPv4";
1362 tmpaddr.sin_addr.s_addr = hdr.v2.addr.ip4.src_addr;
1363 inet_ntop(AF_INET, &tmpaddr.sin_addr, CS &tmpip, sizeof(tmpip));
1364 if (!string_is_ip_address(US tmpip, NULL))
1365 {
1366 DEBUG(D_receive) debug_printf("Invalid %s source IP\n", iptype);
1367 goto proxyfail;
1368 }
1369 proxy_local_address = sender_host_address;
1370 sender_host_address = string_copy(US tmpip);
1371 tmpport = ntohs(hdr.v2.addr.ip4.src_port);
1372 proxy_local_port = sender_host_port;
1373 sender_host_port = tmpport;
1374 /* Save dest ip/port */
1375 tmpaddr.sin_addr.s_addr = hdr.v2.addr.ip4.dst_addr;
1376 inet_ntop(AF_INET, &tmpaddr.sin_addr, CS &tmpip, sizeof(tmpip));
1377 if (!string_is_ip_address(US tmpip, NULL))
1378 {
1379 DEBUG(D_receive) debug_printf("Invalid %s dest port\n", iptype);
1380 goto proxyfail;
1381 }
1382 proxy_external_address = string_copy(US tmpip);
1383 tmpport = ntohs(hdr.v2.addr.ip4.dst_port);
1384 proxy_external_port = tmpport;
1385 goto done;
1386 case 0x21: /* TCPv6 address type */
1387 iptype = US"IPv6";
1388 memmove(tmpaddr6.sin6_addr.s6_addr, hdr.v2.addr.ip6.src_addr, 16);
1389 inet_ntop(AF_INET6, &tmpaddr6.sin6_addr, CS &tmpip6, sizeof(tmpip6));
1390 if (!string_is_ip_address(US tmpip6, NULL))
1391 {
1392 DEBUG(D_receive) debug_printf("Invalid %s source IP\n", iptype);
1393 goto proxyfail;
1394 }
1395 proxy_local_address = sender_host_address;
1396 sender_host_address = string_copy(US tmpip6);
1397 tmpport = ntohs(hdr.v2.addr.ip6.src_port);
1398 proxy_local_port = sender_host_port;
1399 sender_host_port = tmpport;
1400 /* Save dest ip/port */
1401 memmove(tmpaddr6.sin6_addr.s6_addr, hdr.v2.addr.ip6.dst_addr, 16);
1402 inet_ntop(AF_INET6, &tmpaddr6.sin6_addr, CS &tmpip6, sizeof(tmpip6));
1403 if (!string_is_ip_address(US tmpip6, NULL))
1404 {
1405 DEBUG(D_receive) debug_printf("Invalid %s dest port\n", iptype);
1406 goto proxyfail;
1407 }
1408 proxy_external_address = string_copy(US tmpip6);
1409 tmpport = ntohs(hdr.v2.addr.ip6.dst_port);
1410 proxy_external_port = tmpport;
1411 goto done;
1412 default:
1413 DEBUG(D_receive)
1414 debug_printf("Unsupported PROXYv2 connection type: 0x%02x\n",
1415 hdr.v2.fam);
1416 goto proxyfail;
1417 }
1418 /* Unsupported protocol, keep local connection address */
1419 break;
1420 case 0x00: /* LOCAL command */
1421 /* Keep local connection address for LOCAL */
1422 iptype = US"local";
1423 break;
1424 default:
1425 DEBUG(D_receive)
1426 debug_printf("Unsupported PROXYv2 command: 0x%x\n", cmd);
1427 goto proxyfail;
1428 }
1429 }
1430 else if (ret >= 8 && memcmp(hdr.v1.line, "PROXY", 5) == 0)
1431 {
1432 uschar *p;
1433 uschar *end;
1434 uschar *sp; /* Utility variables follow */
1435 int tmp_port;
1436 int r2;
1437 char *endc;
1438
1439 /* get the rest of the line */
1440 r2 = swallow_until_crlf(fd, (uschar*)&hdr, ret, sizeof(hdr)-ret);
1441 if (r2 == -1)
1442 goto proxyfail;
1443 ret += r2;
1444
1445 p = string_copy(hdr.v1.line);
1446 end = memchr(p, '\r', ret - 1);
1447
1448 if (!end || (end == (uschar*)&hdr + ret) || end[1] != '\n')
1449 {
1450 DEBUG(D_receive) debug_printf("Partial or invalid PROXY header\n");
1451 goto proxyfail;
1452 }
1453 *end = '\0'; /* Terminate the string */
1454 size = end + 2 - p; /* Skip header + CRLF */
1455 DEBUG(D_receive) debug_printf("Detected PROXYv1 header\n");
1456 DEBUG(D_receive) debug_printf("Bytes read not within PROXY header: %d\n", ret - size);
1457 /* Step through the string looking for the required fields. Ensure
1458 strict adherence to required formatting, exit for any error. */
1459 p += 5;
1460 if (!isspace(*(p++)))
1461 {
1462 DEBUG(D_receive) debug_printf("Missing space after PROXY command\n");
1463 goto proxyfail;
1464 }
1465 if (!Ustrncmp(p, CCS"TCP4", 4))
1466 iptype = US"IPv4";
1467 else if (!Ustrncmp(p,CCS"TCP6", 4))
1468 iptype = US"IPv6";
1469 else if (!Ustrncmp(p,CCS"UNKNOWN", 7))
1470 {
1471 iptype = US"Unknown";
1472 goto done;
1473 }
1474 else
1475 {
1476 DEBUG(D_receive) debug_printf("Invalid TCP type\n");
1477 goto proxyfail;
1478 }
1479
1480 p += Ustrlen(iptype);
1481 if (!isspace(*(p++)))
1482 {
1483 DEBUG(D_receive) debug_printf("Missing space after TCP4/6 command\n");
1484 goto proxyfail;
1485 }
1486 /* Find the end of the arg */
1487 if ((sp = Ustrchr(p, ' ')) == NULL)
1488 {
1489 DEBUG(D_receive)
1490 debug_printf("Did not find proxied src %s\n", iptype);
1491 goto proxyfail;
1492 }
1493 *sp = '\0';
1494 if(!string_is_ip_address(p, NULL))
1495 {
1496 DEBUG(D_receive)
1497 debug_printf("Proxied src arg is not an %s address\n", iptype);
1498 goto proxyfail;
1499 }
1500 proxy_local_address = sender_host_address;
1501 sender_host_address = p;
1502 p = sp + 1;
1503 if ((sp = Ustrchr(p, ' ')) == NULL)
1504 {
1505 DEBUG(D_receive)
1506 debug_printf("Did not find proxy dest %s\n", iptype);
1507 goto proxyfail;
1508 }
1509 *sp = '\0';
1510 if(!string_is_ip_address(p, NULL))
1511 {
1512 DEBUG(D_receive)
1513 debug_printf("Proxy dest arg is not an %s address\n", iptype);
1514 goto proxyfail;
1515 }
1516 proxy_external_address = p;
1517 p = sp + 1;
1518 if ((sp = Ustrchr(p, ' ')) == NULL)
1519 {
1520 DEBUG(D_receive) debug_printf("Did not find proxied src port\n");
1521 goto proxyfail;
1522 }
1523 *sp = '\0';
1524 tmp_port = strtol(CCS p, &endc, 10);
1525 if (*endc || tmp_port == 0)
1526 {
1527 DEBUG(D_receive)
1528 debug_printf("Proxied src port '%s' not an integer\n", p);
1529 goto proxyfail;
1530 }
1531 proxy_local_port = sender_host_port;
1532 sender_host_port = tmp_port;
1533 p = sp + 1;
1534 if ((sp = Ustrchr(p, '\0')) == NULL)
1535 {
1536 DEBUG(D_receive) debug_printf("Did not find proxy dest port\n");
1537 goto proxyfail;
1538 }
1539 tmp_port = strtol(CCS p, &endc, 10);
1540 if (*endc || tmp_port == 0)
1541 {
1542 DEBUG(D_receive)
1543 debug_printf("Proxy dest port '%s' not an integer\n", p);
1544 goto proxyfail;
1545 }
1546 proxy_external_port = tmp_port;
1547 /* Already checked for /r /n above. Good V1 header received. */
1548 }
1549 else
1550 {
1551 /* Wrong protocol */
1552 DEBUG(D_receive) debug_printf("Invalid proxy protocol version negotiation\n");
1553 (void) swallow_until_crlf(fd, (uschar*)&hdr, ret, sizeof(hdr)-ret);
1554 goto proxyfail;
1555 }
1556
1557 done:
1558 DEBUG(D_receive)
1559 debug_printf("Valid %s sender from Proxy Protocol header\n", iptype);
1560 yield = proxy_session;
1561
1562 /* Don't flush any potential buffer contents. Any input on proxyfail
1563 should cause a synchronization failure */
1564
1565 proxyfail:
1566 DEBUG(D_receive) if (had_command_timeout)
1567 debug_printf("Timeout while reading proxy header\n");
1568
1569 bad:
1570 if (yield)
1571 {
1572 sender_host_name = NULL;
1573 (void) host_name_lookup();
1574 host_build_sender_fullhost();
1575 }
1576 else
1577 {
1578 f.proxy_session_failed = TRUE;
1579 DEBUG(D_receive)
1580 debug_printf("Failure to extract proxied host, only QUIT allowed\n");
1581 }
1582
1583 ALARM(0);
1584 return;
1585 }
1586 #endif
1587
1588 /*************************************************
1589 * Read one command line *
1590 *************************************************/
1591
1592 /* Strictly, SMTP commands coming over the net are supposed to end with CRLF.
1593 There are sites that don't do this, and in any case internal SMTP probably
1594 should check only for LF. Consequently, we check here for LF only. The line
1595 ends up with [CR]LF removed from its end. If we get an overlong line, treat as
1596 an unknown command. The command is read into the global smtp_cmd_buffer so that
1597 it is available via $smtp_command.
1598
1599 The character reading routine sets up a timeout for each block actually read
1600 from the input (which may contain more than one command). We set up a special
1601 signal handler that closes down the session on a timeout. Control does not
1602 return when it runs.
1603
1604 Arguments:
1605 check_sync if TRUE, check synchronization rules if global option is TRUE
1606 buffer_lim maximum to buffer in lower layer
1607
1608 Returns: a code identifying the command (enumerated above)
1609 */
1610
1611 static int
smtp_read_command(BOOL check_sync,unsigned buffer_lim)1612 smtp_read_command(BOOL check_sync, unsigned buffer_lim)
1613 {
1614 int c;
1615 int ptr = 0;
1616 BOOL hadnull = FALSE;
1617
1618 had_command_timeout = 0;
1619 os_non_restarting_signal(SIGALRM, command_timeout_handler);
1620
1621 while ((c = (receive_getc)(buffer_lim)) != '\n' && c != EOF)
1622 {
1623 if (ptr >= SMTP_CMD_BUFFER_SIZE)
1624 {
1625 os_non_restarting_signal(SIGALRM, sigalrm_handler);
1626 return OTHER_CMD;
1627 }
1628 if (c == 0)
1629 {
1630 hadnull = TRUE;
1631 c = '?';
1632 }
1633 smtp_cmd_buffer[ptr++] = c;
1634 }
1635
1636 receive_linecount++; /* For BSMTP errors */
1637 os_non_restarting_signal(SIGALRM, sigalrm_handler);
1638
1639 /* If hit end of file, return pseudo EOF command. Whether we have a
1640 part-line already read doesn't matter, since this is an error state. */
1641
1642 if (c == EOF) return EOF_CMD;
1643
1644 /* Remove any CR and white space at the end of the line, and terminate the
1645 string. */
1646
1647 while (ptr > 0 && isspace(smtp_cmd_buffer[ptr-1])) ptr--;
1648 smtp_cmd_buffer[ptr] = 0;
1649
1650 DEBUG(D_receive) debug_printf("SMTP<< %s\n", smtp_cmd_buffer);
1651
1652 /* NULLs are not allowed in SMTP commands */
1653
1654 if (hadnull) return BADCHAR_CMD;
1655
1656 /* Scan command list and return identity, having set the data pointer
1657 to the start of the actual data characters. Check for SMTP synchronization
1658 if required. */
1659
1660 for (smtp_cmd_list * p = cmd_list; p < cmd_list_end; p++)
1661 {
1662 #ifdef SUPPORT_PROXY
1663 /* Only allow QUIT command if Proxy Protocol parsing failed */
1664 if (proxy_session && f.proxy_session_failed && p->cmd != QUIT_CMD)
1665 continue;
1666 #endif
1667 if ( p->len
1668 && strncmpic(smtp_cmd_buffer, US p->name, p->len) == 0
1669 && ( smtp_cmd_buffer[p->len-1] == ':' /* "mail from:" or "rcpt to:" */
1670 || smtp_cmd_buffer[p->len] == 0
1671 || smtp_cmd_buffer[p->len] == ' '
1672 ) )
1673 {
1674 if (smtp_inptr < smtp_inend && /* Outstanding input */
1675 p->cmd < sync_cmd_limit && /* Command should sync */
1676 check_sync && /* Local flag set */
1677 smtp_enforce_sync && /* Global flag set */
1678 sender_host_address != NULL && /* Not local input */
1679 !f.sender_host_notsocket) /* Really is a socket */
1680 return BADSYN_CMD;
1681
1682 /* The variables $smtp_command and $smtp_command_argument point into the
1683 unmodified input buffer. A copy of the latter is taken for actual
1684 processing, so that it can be chopped up into separate parts if necessary,
1685 for example, when processing a MAIL command options such as SIZE that can
1686 follow the sender address. */
1687
1688 smtp_cmd_argument = smtp_cmd_buffer + p->len;
1689 while (isspace(*smtp_cmd_argument)) smtp_cmd_argument++;
1690 Ustrcpy(smtp_data_buffer, smtp_cmd_argument);
1691 smtp_cmd_data = smtp_data_buffer;
1692
1693 /* Count non-mail commands from those hosts that are controlled in this
1694 way. The default is all hosts. We don't waste effort checking the list
1695 until we get a non-mail command, but then cache the result to save checking
1696 again. If there's a DEFER while checking the host, assume it's in the list.
1697
1698 Note that one instance of RSET, EHLO/HELO, and STARTTLS is allowed at the
1699 start of each incoming message by fiddling with the value in the table. */
1700
1701 if (!p->is_mail_cmd)
1702 {
1703 if (count_nonmail == TRUE_UNSET) count_nonmail =
1704 verify_check_host(&smtp_accept_max_nonmail_hosts) != FAIL;
1705 if (count_nonmail && ++nonmail_command_count > smtp_accept_max_nonmail)
1706 return TOO_MANY_NONMAIL_CMD;
1707 }
1708
1709 /* If there is data for a command that does not expect it, generate the
1710 error here. */
1711
1712 return (p->has_arg || *smtp_cmd_data == 0)? p->cmd : BADARG_CMD;
1713 }
1714 }
1715
1716 #ifdef SUPPORT_PROXY
1717 /* Only allow QUIT command if Proxy Protocol parsing failed */
1718 if (proxy_session && f.proxy_session_failed)
1719 return PROXY_FAIL_IGNORE_CMD;
1720 #endif
1721
1722 /* Enforce synchronization for unknown commands */
1723
1724 if ( smtp_inptr < smtp_inend /* Outstanding input */
1725 && check_sync /* Local flag set */
1726 && smtp_enforce_sync /* Global flag set */
1727 && sender_host_address /* Not local input */
1728 && !f.sender_host_notsocket) /* Really is a socket */
1729 return BADSYN_CMD;
1730
1731 return OTHER_CMD;
1732 }
1733
1734
1735
1736 /*************************************************
1737 * Forced closedown of call *
1738 *************************************************/
1739
1740 /* This function is called from log.c when Exim is dying because of a serious
1741 disaster, and also from some other places. If an incoming non-batched SMTP
1742 channel is open, it swallows the rest of the incoming message if in the DATA
1743 phase, sends the reply string, and gives an error to all subsequent commands
1744 except QUIT. The existence of an SMTP call is detected by the non-NULLness of
1745 smtp_in.
1746
1747 Arguments:
1748 message SMTP reply string to send, excluding the code
1749
1750 Returns: nothing
1751 */
1752
1753 void
smtp_closedown(uschar * message)1754 smtp_closedown(uschar *message)
1755 {
1756 if (!smtp_in || smtp_batched_input) return;
1757 receive_swallow_smtp();
1758 smtp_printf("421 %s\r\n", FALSE, message);
1759
1760 for (;;) switch(smtp_read_command(FALSE, GETC_BUFFER_UNLIMITED))
1761 {
1762 case EOF_CMD:
1763 return;
1764
1765 case QUIT_CMD:
1766 f.smtp_in_quit = TRUE;
1767 smtp_printf("221 %s closing connection\r\n", FALSE, smtp_active_hostname);
1768 mac_smtp_fflush();
1769 return;
1770
1771 case RSET_CMD:
1772 smtp_printf("250 Reset OK\r\n", FALSE);
1773 break;
1774
1775 default:
1776 smtp_printf("421 %s\r\n", FALSE, message);
1777 break;
1778 }
1779 }
1780
1781
1782
1783
1784 /*************************************************
1785 * Set up connection info for logging *
1786 *************************************************/
1787
1788 /* This function is called when logging information about an SMTP connection.
1789 It sets up appropriate source information, depending on the type of connection.
1790 If sender_fullhost is NULL, we are at a very early stage of the connection;
1791 just use the IP address.
1792
1793 Argument: none
1794 Returns: a string describing the connection
1795 */
1796
1797 uschar *
smtp_get_connection_info(void)1798 smtp_get_connection_info(void)
1799 {
1800 const uschar * hostname = sender_fullhost
1801 ? sender_fullhost : sender_host_address;
1802
1803 if (host_checking)
1804 return string_sprintf("SMTP connection from %s", hostname);
1805
1806 if (f.sender_host_unknown || f.sender_host_notsocket)
1807 return string_sprintf("SMTP connection from %s", sender_ident);
1808
1809 if (f.is_inetd)
1810 return string_sprintf("SMTP connection from %s (via inetd)", hostname);
1811
1812 if (LOGGING(incoming_interface) && interface_address)
1813 return string_sprintf("SMTP connection from %s I=[%s]:%d", hostname,
1814 interface_address, interface_port);
1815
1816 return string_sprintf("SMTP connection from %s", hostname);
1817 }
1818
1819
1820
1821 #ifndef DISABLE_TLS
1822 /* Append TLS-related information to a log line
1823
1824 Arguments:
1825 g String under construction: allocated string to extend, or NULL
1826
1827 Returns: Allocated string or NULL
1828 */
1829 static gstring *
s_tlslog(gstring * g)1830 s_tlslog(gstring * g)
1831 {
1832 if (LOGGING(tls_cipher) && tls_in.cipher)
1833 {
1834 g = string_append(g, 2, US" X=", tls_in.cipher);
1835 #ifndef DISABLE_TLS_RESUME
1836 if (LOGGING(tls_resumption) && tls_in.resumption & RESUME_USED)
1837 g = string_catn(g, US"*", 1);
1838 #endif
1839 }
1840 if (LOGGING(tls_certificate_verified) && tls_in.cipher)
1841 g = string_append(g, 2, US" CV=", tls_in.certificate_verified? "yes":"no");
1842 if (LOGGING(tls_peerdn) && tls_in.peerdn)
1843 g = string_append(g, 3, US" DN=\"", string_printing(tls_in.peerdn), US"\"");
1844 if (LOGGING(tls_sni) && tls_in.sni)
1845 g = string_append(g, 2, US" SNI=", string_printing2(tls_in.sni, SP_TAB|SP_SPACE));
1846 return g;
1847 }
1848 #endif
1849
1850
1851
1852 static gstring *
s_connhad_log(gstring * g)1853 s_connhad_log(gstring * g)
1854 {
1855 const uschar * sep = smtp_connection_had[SMTP_HBUFF_SIZE-1] != SCH_NONE
1856 ? US" C=..." : US" C=";
1857
1858 for (int i = smtp_ch_index; i < SMTP_HBUFF_SIZE; i++)
1859 if (smtp_connection_had[i] != SCH_NONE)
1860 {
1861 g = string_append(g, 2, sep, smtp_names[smtp_connection_had[i]]);
1862 sep = US",";
1863 }
1864 for (int i = 0; i < smtp_ch_index; i++, sep = US",")
1865 g = string_append(g, 2, sep, smtp_names[smtp_connection_had[i]]);
1866 return g;
1867 }
1868
1869
1870 /*************************************************
1871 * Log lack of MAIL if so configured *
1872 *************************************************/
1873
1874 /* This function is called when an SMTP session ends. If the log selector
1875 smtp_no_mail is set, write a log line giving some details of what has happened
1876 in the SMTP session.
1877
1878 Arguments: none
1879 Returns: nothing
1880 */
1881
1882 void
smtp_log_no_mail(void)1883 smtp_log_no_mail(void)
1884 {
1885 uschar * s;
1886 gstring * g = NULL;
1887
1888 if (smtp_mailcmd_count > 0 || !LOGGING(smtp_no_mail))
1889 return;
1890
1891 if (sender_host_authenticated)
1892 {
1893 g = string_append(g, 2, US" A=", sender_host_authenticated);
1894 if (authenticated_id) g = string_append(g, 2, US":", authenticated_id);
1895 }
1896
1897 #ifndef DISABLE_TLS
1898 g = s_tlslog(g);
1899 #endif
1900
1901 g = s_connhad_log(g);
1902
1903 if (!(s = string_from_gstring(g))) s = US"";
1904
1905 log_write(0, LOG_MAIN, "no MAIL in %sSMTP connection from %s D=%s%s",
1906 f.tcp_in_fastopen ? f.tcp_in_fastopen_data ? US"TFO* " : US"TFO " : US"",
1907 host_and_ident(FALSE), string_timesince(&smtp_connection_start), s);
1908 }
1909
1910
1911 /* Return list of recent smtp commands */
1912
1913 uschar *
smtp_cmd_hist(void)1914 smtp_cmd_hist(void)
1915 {
1916 gstring * list = NULL;
1917 uschar * s;
1918
1919 for (int i = smtp_ch_index; i < SMTP_HBUFF_SIZE; i++)
1920 if (smtp_connection_had[i] != SCH_NONE)
1921 list = string_append_listele(list, ',', smtp_names[smtp_connection_had[i]]);
1922
1923 for (int i = 0; i < smtp_ch_index; i++)
1924 list = string_append_listele(list, ',', smtp_names[smtp_connection_had[i]]);
1925
1926 s = string_from_gstring(list);
1927 return s ? s : US"";
1928 }
1929
1930
1931
1932
1933 /*************************************************
1934 * Check HELO line and set sender_helo_name *
1935 *************************************************/
1936
1937 /* Check the format of a HELO line. The data for HELO/EHLO is supposed to be
1938 the domain name of the sending host, or an ip literal in square brackets. The
1939 argument is placed in sender_helo_name, which is in malloc store, because it
1940 must persist over multiple incoming messages. If helo_accept_junk is set, this
1941 host is permitted to send any old junk (needed for some broken hosts).
1942 Otherwise, helo_allow_chars can be used for rogue characters in general
1943 (typically people want to let in underscores).
1944
1945 Argument:
1946 s the data portion of the line (already past any white space)
1947
1948 Returns: TRUE or FALSE
1949 */
1950
1951 static BOOL
check_helo(uschar * s)1952 check_helo(uschar *s)
1953 {
1954 uschar *start = s;
1955 uschar *end = s + Ustrlen(s);
1956 BOOL yield = fl.helo_accept_junk;
1957
1958 /* Discard any previous helo name */
1959
1960 sender_helo_name = NULL;
1961
1962 /* Skip tests if junk is permitted. */
1963
1964 if (!yield)
1965
1966 /* Allow the new standard form for IPv6 address literals, namely,
1967 [IPv6:....], and because someone is bound to use it, allow an equivalent
1968 IPv4 form. Allow plain addresses as well. */
1969
1970 if (*s == '[')
1971 {
1972 if (end[-1] == ']')
1973 {
1974 end[-1] = 0;
1975 if (strncmpic(s, US"[IPv6:", 6) == 0)
1976 yield = (string_is_ip_address(s+6, NULL) == 6);
1977 else if (strncmpic(s, US"[IPv4:", 6) == 0)
1978 yield = (string_is_ip_address(s+6, NULL) == 4);
1979 else
1980 yield = (string_is_ip_address(s+1, NULL) != 0);
1981 end[-1] = ']';
1982 }
1983 }
1984
1985 /* Non-literals must be alpha, dot, hyphen, plus any non-valid chars
1986 that have been configured (usually underscore - sigh). */
1987
1988 else if (*s)
1989 for (yield = TRUE; *s; s++)
1990 if (!isalnum(*s) && *s != '.' && *s != '-' &&
1991 Ustrchr(helo_allow_chars, *s) == NULL)
1992 {
1993 yield = FALSE;
1994 break;
1995 }
1996
1997 /* Save argument if OK */
1998
1999 if (yield) sender_helo_name = string_copy_perm(start, TRUE);
2000 return yield;
2001 }
2002
2003
2004
2005
2006
2007 /*************************************************
2008 * Extract SMTP command option *
2009 *************************************************/
2010
2011 /* This function picks the next option setting off the end of smtp_cmd_data. It
2012 is called for MAIL FROM and RCPT TO commands, to pick off the optional ESMTP
2013 things that can appear there.
2014
2015 Arguments:
2016 name point this at the name
2017 value point this at the data string
2018
2019 Returns: TRUE if found an option
2020 */
2021
2022 static BOOL
extract_option(uschar ** name,uschar ** value)2023 extract_option(uschar **name, uschar **value)
2024 {
2025 uschar *n;
2026 uschar *v;
2027 if (Ustrlen(smtp_cmd_data) <= 0) return FALSE;
2028 v = smtp_cmd_data + Ustrlen(smtp_cmd_data) - 1;
2029 while (v > smtp_cmd_data && isspace(*v)) v--;
2030 v[1] = 0;
2031
2032 while (v > smtp_cmd_data && *v != '=' && !isspace(*v))
2033 {
2034 /* Take care to not stop at a space embedded in a quoted local-part */
2035 if (*v == '"')
2036 {
2037 do v--; while (v > smtp_cmd_data && *v != '"');
2038 if (v <= smtp_cmd_data) return FALSE;
2039 }
2040 v--;
2041 }
2042 if (v <= smtp_cmd_data) return FALSE;
2043
2044 n = v;
2045 if (*v == '=')
2046 {
2047 while (n > smtp_cmd_data && isalpha(n[-1])) n--;
2048 /* RFC says SP, but TAB seen in wild and other major MTAs accept it */
2049 if (n <= smtp_cmd_data || !isspace(n[-1])) return FALSE;
2050 n[-1] = 0;
2051 }
2052 else
2053 {
2054 n++;
2055 }
2056 *v++ = 0;
2057 *name = n;
2058 *value = v;
2059 return TRUE;
2060 }
2061
2062
2063
2064
2065
2066 /*************************************************
2067 * Reset for new message *
2068 *************************************************/
2069
2070 /* This function is called whenever the SMTP session is reset from
2071 within either of the setup functions; also from the daemon loop.
2072
2073 Argument: the stacking pool storage reset point
2074 Returns: nothing
2075 */
2076
2077 void *
smtp_reset(void * reset_point)2078 smtp_reset(void *reset_point)
2079 {
2080 recipients_list = NULL;
2081 rcpt_count = rcpt_defer_count = rcpt_fail_count =
2082 raw_recipients_count = recipients_count = recipients_list_max = 0;
2083 message_linecount = 0;
2084 message_size = -1;
2085 message_body = message_body_end = NULL;
2086 acl_added_headers = NULL;
2087 acl_removed_headers = NULL;
2088 f.queue_only_policy = FALSE;
2089 rcpt_smtp_response = NULL;
2090 fl.rcpt_smtp_response_same = TRUE;
2091 fl.rcpt_in_progress = FALSE;
2092 f.deliver_freeze = FALSE; /* Can be set by ACL */
2093 freeze_tell = freeze_tell_config; /* Can be set by ACL */
2094 fake_response = OK; /* Can be set by ACL */
2095 #ifdef WITH_CONTENT_SCAN
2096 f.no_mbox_unspool = FALSE; /* Can be set by ACL */
2097 #endif
2098 f.submission_mode = FALSE; /* Can be set by ACL */
2099 f.suppress_local_fixups = f.suppress_local_fixups_default; /* Can be set by ACL */
2100 f.active_local_from_check = local_from_check; /* Can be set by ACL */
2101 f.active_local_sender_retain = local_sender_retain; /* Can be set by ACL */
2102 sending_ip_address = NULL;
2103 return_path = sender_address = NULL;
2104 deliver_localpart_data = deliver_domain_data =
2105 recipient_data = sender_data = NULL; /* Can be set by ACL */
2106 recipient_verify_failure = NULL;
2107 deliver_localpart_parent = deliver_localpart_orig = NULL;
2108 deliver_domain_parent = deliver_domain_orig = NULL;
2109 callout_address = NULL;
2110 submission_name = NULL; /* Can be set by ACL */
2111 raw_sender = NULL; /* After SMTP rewrite, before qualifying */
2112 sender_address_unrewritten = NULL; /* Set only after verify rewrite */
2113 sender_verified_list = NULL; /* No senders verified */
2114 memset(sender_address_cache, 0, sizeof(sender_address_cache));
2115 memset(sender_domain_cache, 0, sizeof(sender_domain_cache));
2116
2117 authenticated_sender = NULL;
2118 #ifdef EXPERIMENTAL_BRIGHTMAIL
2119 bmi_run = 0;
2120 bmi_verdicts = NULL;
2121 #endif
2122 dnslist_domain = dnslist_matched = NULL;
2123 #ifdef SUPPORT_SPF
2124 spf_header_comment = spf_received = spf_result = spf_smtp_comment = NULL;
2125 spf_result_guessed = FALSE;
2126 #endif
2127 #ifndef DISABLE_DKIM
2128 dkim_cur_signer = dkim_signers =
2129 dkim_signing_domain = dkim_signing_selector = dkim_signatures = NULL;
2130 dkim_cur_signer = dkim_signers = dkim_signing_domain = dkim_signing_selector = NULL;
2131 f.dkim_disable_verify = FALSE;
2132 dkim_collect_input = 0;
2133 dkim_verify_overall = dkim_verify_status = dkim_verify_reason = NULL;
2134 dkim_key_length = 0;
2135 #endif
2136 #ifdef SUPPORT_DMARC
2137 f.dmarc_has_been_checked = f.dmarc_disable_verify = f.dmarc_enable_forensic = FALSE;
2138 dmarc_domain_policy = dmarc_status = dmarc_status_text =
2139 dmarc_used_domain = NULL;
2140 #endif
2141 #ifdef EXPERIMENTAL_ARC
2142 arc_state = arc_state_reason = NULL;
2143 arc_received_instance = 0;
2144 #endif
2145 dsn_ret = 0;
2146 dsn_envid = NULL;
2147 deliver_host = deliver_host_address = NULL; /* Can be set by ACL */
2148 #ifndef DISABLE_PRDR
2149 prdr_requested = FALSE;
2150 #endif
2151 #ifdef SUPPORT_I18N
2152 message_smtputf8 = FALSE;
2153 #endif
2154 body_linecount = body_zerocount = 0;
2155
2156 sender_rate = sender_rate_limit = sender_rate_period = NULL;
2157 ratelimiters_mail = NULL; /* Updated by ratelimit ACL condition */
2158 /* Note that ratelimiters_conn persists across resets. */
2159
2160 /* Reset message ACL variables */
2161
2162 acl_var_m = NULL;
2163
2164 /* Warning log messages are saved in malloc store. They are saved to avoid
2165 repetition in the same message, but it seems right to repeat them for different
2166 messages. */
2167
2168 while (acl_warn_logged)
2169 {
2170 string_item *this = acl_warn_logged;
2171 acl_warn_logged = acl_warn_logged->next;
2172 store_free(this);
2173 }
2174
2175 message_tidyup();
2176 store_reset(reset_point);
2177
2178 message_start();
2179 return store_mark();
2180 }
2181
2182
2183
2184
2185
2186 /*************************************************
2187 * Initialize for incoming batched SMTP message *
2188 *************************************************/
2189
2190 /* This function is called from smtp_setup_msg() in the case when
2191 smtp_batched_input is true. This happens when -bS is used to pass a whole batch
2192 of messages in one file with SMTP commands between them. All errors must be
2193 reported by sending a message, and only MAIL FROM, RCPT TO, and DATA are
2194 relevant. After an error on a sender, or an invalid recipient, the remainder
2195 of the message is skipped. The value of received_protocol is already set.
2196
2197 Argument: none
2198 Returns: > 0 message successfully started (reached DATA)
2199 = 0 QUIT read or end of file reached
2200 < 0 should not occur
2201 */
2202
2203 static int
smtp_setup_batch_msg(void)2204 smtp_setup_batch_msg(void)
2205 {
2206 int done = 0;
2207 rmark reset_point = store_mark();
2208
2209 /* Save the line count at the start of each transaction - single commands
2210 like HELO and RSET count as whole transactions. */
2211
2212 bsmtp_transaction_linecount = receive_linecount;
2213
2214 if ((receive_feof)()) return 0; /* Treat EOF as QUIT */
2215
2216 cancel_cutthrough_connection(TRUE, US"smtp_setup_batch_msg");
2217 reset_point = smtp_reset(reset_point); /* Reset for start of message */
2218
2219 /* Deal with SMTP commands. This loop is exited by setting done to a POSITIVE
2220 value. The values are 2 larger than the required yield of the function. */
2221
2222 while (done <= 0)
2223 {
2224 uschar *errmess;
2225 uschar *recipient = NULL;
2226 int start, end, sender_domain, recipient_domain;
2227
2228 switch(smtp_read_command(FALSE, GETC_BUFFER_UNLIMITED))
2229 {
2230 /* The HELO/EHLO commands set sender_address_helo if they have
2231 valid data; otherwise they are ignored, except that they do
2232 a reset of the state. */
2233
2234 case HELO_CMD:
2235 case EHLO_CMD:
2236
2237 check_helo(smtp_cmd_data);
2238 /* Fall through */
2239
2240 case RSET_CMD:
2241 cancel_cutthrough_connection(TRUE, US"RSET received");
2242 reset_point = smtp_reset(reset_point);
2243 bsmtp_transaction_linecount = receive_linecount;
2244 break;
2245
2246
2247 /* The MAIL FROM command requires an address as an operand. All we
2248 do here is to parse it for syntactic correctness. The form "<>" is
2249 a special case which converts into an empty string. The start/end
2250 pointers in the original are not used further for this address, as
2251 it is the canonical extracted address which is all that is kept. */
2252
2253 case MAIL_CMD:
2254 smtp_mailcmd_count++; /* Count for no-mail log */
2255 if (sender_address)
2256 /* The function moan_smtp_batch() does not return. */
2257 moan_smtp_batch(smtp_cmd_buffer, "503 Sender already given");
2258
2259 if (smtp_cmd_data[0] == 0)
2260 /* The function moan_smtp_batch() does not return. */
2261 moan_smtp_batch(smtp_cmd_buffer, "501 MAIL FROM must have an address operand");
2262
2263 /* Reset to start of message */
2264
2265 cancel_cutthrough_connection(TRUE, US"MAIL received");
2266 reset_point = smtp_reset(reset_point);
2267
2268 /* Apply SMTP rewrite */
2269
2270 raw_sender = rewrite_existflags & rewrite_smtp
2271 /* deconst ok as smtp_cmd_data was not const */
2272 ? US rewrite_one(smtp_cmd_data, rewrite_smtp|rewrite_smtp_sender, NULL,
2273 FALSE, US"", global_rewrite_rules)
2274 : smtp_cmd_data;
2275
2276 /* Extract the address; the TRUE flag allows <> as valid */
2277
2278 raw_sender =
2279 parse_extract_address(raw_sender, &errmess, &start, &end, &sender_domain,
2280 TRUE);
2281
2282 if (!raw_sender)
2283 /* The function moan_smtp_batch() does not return. */
2284 moan_smtp_batch(smtp_cmd_buffer, "501 %s", errmess);
2285
2286 sender_address = string_copy(raw_sender);
2287
2288 /* Qualify unqualified sender addresses if permitted to do so. */
2289
2290 if ( !sender_domain
2291 && sender_address[0] != 0 && sender_address[0] != '@')
2292 if (f.allow_unqualified_sender)
2293 {
2294 /* deconst ok as sender_address was not const */
2295 sender_address = US rewrite_address_qualify(sender_address, FALSE);
2296 DEBUG(D_receive) debug_printf("unqualified address %s accepted "
2297 "and rewritten\n", raw_sender);
2298 }
2299 /* The function moan_smtp_batch() does not return. */
2300 else
2301 moan_smtp_batch(smtp_cmd_buffer, "501 sender address must contain "
2302 "a domain");
2303 break;
2304
2305
2306 /* The RCPT TO command requires an address as an operand. All we do
2307 here is to parse it for syntactic correctness. There may be any number
2308 of RCPT TO commands, specifying multiple senders. We build them all into
2309 a data structure that is in argc/argv format. The start/end values
2310 given by parse_extract_address are not used, as we keep only the
2311 extracted address. */
2312
2313 case RCPT_CMD:
2314 if (!sender_address)
2315 /* The function moan_smtp_batch() does not return. */
2316 moan_smtp_batch(smtp_cmd_buffer, "503 No sender yet given");
2317
2318 if (smtp_cmd_data[0] == 0)
2319 /* The function moan_smtp_batch() does not return. */
2320 moan_smtp_batch(smtp_cmd_buffer,
2321 "501 RCPT TO must have an address operand");
2322
2323 /* Check maximum number allowed */
2324
2325 if (recipients_max > 0 && recipients_count + 1 > recipients_max)
2326 /* The function moan_smtp_batch() does not return. */
2327 moan_smtp_batch(smtp_cmd_buffer, "%s too many recipients",
2328 recipients_max_reject? "552": "452");
2329
2330 /* Apply SMTP rewrite, then extract address. Don't allow "<>" as a
2331 recipient address */
2332
2333 recipient = rewrite_existflags & rewrite_smtp
2334 /* deconst ok as smtp_cmd_data was not const */
2335 ? US rewrite_one(smtp_cmd_data, rewrite_smtp, NULL, FALSE, US"",
2336 global_rewrite_rules)
2337 : smtp_cmd_data;
2338
2339 recipient = parse_extract_address(recipient, &errmess, &start, &end,
2340 &recipient_domain, FALSE);
2341
2342 if (!recipient)
2343 /* The function moan_smtp_batch() does not return. */
2344 moan_smtp_batch(smtp_cmd_buffer, "501 %s", errmess);
2345
2346 /* If the recipient address is unqualified, qualify it if permitted. Then
2347 add it to the list of recipients. */
2348
2349 if (!recipient_domain)
2350 if (f.allow_unqualified_recipient)
2351 {
2352 DEBUG(D_receive) debug_printf("unqualified address %s accepted\n",
2353 recipient);
2354 /* deconst ok as recipient was not const */
2355 recipient = US rewrite_address_qualify(recipient, TRUE);
2356 }
2357 /* The function moan_smtp_batch() does not return. */
2358 else
2359 moan_smtp_batch(smtp_cmd_buffer,
2360 "501 recipient address must contain a domain");
2361
2362 receive_add_recipient(recipient, -1);
2363 break;
2364
2365
2366 /* The DATA command is legal only if it follows successful MAIL FROM
2367 and RCPT TO commands. This function is complete when a valid DATA
2368 command is encountered. */
2369
2370 case DATA_CMD:
2371 if (!sender_address || recipients_count <= 0)
2372 /* The function moan_smtp_batch() does not return. */
2373 if (!sender_address)
2374 moan_smtp_batch(smtp_cmd_buffer,
2375 "503 MAIL FROM:<sender> command must precede DATA");
2376 else
2377 moan_smtp_batch(smtp_cmd_buffer,
2378 "503 RCPT TO:<recipient> must precede DATA");
2379 else
2380 {
2381 done = 3; /* DATA successfully achieved */
2382 message_ended = END_NOTENDED; /* Indicate in middle of message */
2383 }
2384 break;
2385
2386
2387 /* The VRFY, EXPN, HELP, ETRN, and NOOP commands are ignored. */
2388
2389 case VRFY_CMD:
2390 case EXPN_CMD:
2391 case HELP_CMD:
2392 case NOOP_CMD:
2393 case ETRN_CMD:
2394 bsmtp_transaction_linecount = receive_linecount;
2395 break;
2396
2397
2398 case QUIT_CMD:
2399 f.smtp_in_quit = TRUE;
2400 case EOF_CMD:
2401 done = 2;
2402 break;
2403
2404
2405 case BADARG_CMD:
2406 /* The function moan_smtp_batch() does not return. */
2407 moan_smtp_batch(smtp_cmd_buffer, "501 Unexpected argument data");
2408 break;
2409
2410
2411 case BADCHAR_CMD:
2412 /* The function moan_smtp_batch() does not return. */
2413 moan_smtp_batch(smtp_cmd_buffer, "501 Unexpected NULL in SMTP command");
2414 break;
2415
2416
2417 default:
2418 /* The function moan_smtp_batch() does not return. */
2419 moan_smtp_batch(smtp_cmd_buffer, "500 Command unrecognized");
2420 break;
2421 }
2422 }
2423
2424 return done - 2; /* Convert yield values */
2425 }
2426
2427
2428
2429
2430 #ifndef DISABLE_TLS
2431 static BOOL
smtp_log_tls_fail(uschar * errstr)2432 smtp_log_tls_fail(uschar * errstr)
2433 {
2434 uschar * conn_info = smtp_get_connection_info();
2435
2436 if (Ustrncmp(conn_info, US"SMTP ", 5) == 0) conn_info += 5;
2437 /* I'd like to get separated H= here, but too hard for now */
2438
2439 log_write(0, LOG_MAIN, "TLS error on %s %s", conn_info, errstr);
2440 return FALSE;
2441 }
2442 #endif
2443 #ifdef USE_TCP_WRAPPERS
2444 struct request_info tcpwrap_ri;
2445 #endif
2446
2447
2448
2449
2450 #ifdef TCP_FASTOPEN
2451 static void
tfo_in_check(void)2452 tfo_in_check(void)
2453 {
2454 # ifdef __FreeBSD__
2455 int is_fastopen;
2456 socklen_t len = sizeof(is_fastopen);
2457
2458 /* The tinfo TCPOPT_FAST_OPEN bit seems unreliable, and we don't see state
2459 TCP_SYN_RCV (as of 12.1) so no idea about data-use. */
2460
2461 if (getsockopt(fileno(smtp_out), IPPROTO_TCP, TCP_FASTOPEN, &is_fastopen, &len) == 0)
2462 {
2463 if (is_fastopen)
2464 {
2465 DEBUG(D_receive)
2466 debug_printf("TFO mode connection (TCP_FASTOPEN getsockopt)\n");
2467 f.tcp_in_fastopen = TRUE;
2468 }
2469 }
2470 else DEBUG(D_receive)
2471 debug_printf("TCP_INFO getsockopt: %s\n", strerror(errno));
2472
2473 # elif defined(TCP_INFO)
2474 struct tcp_info tinfo;
2475 socklen_t len = sizeof(tinfo);
2476
2477 if (getsockopt(fileno(smtp_out), IPPROTO_TCP, TCP_INFO, &tinfo, &len) == 0)
2478 # ifdef TCPI_OPT_SYN_DATA /* FreeBSD 11,12 do not seem to have this yet */
2479 if (tinfo.tcpi_options & TCPI_OPT_SYN_DATA)
2480 {
2481 DEBUG(D_receive)
2482 debug_printf("TFO mode connection (ACKd data-on-SYN)\n");
2483 f.tcp_in_fastopen_data = f.tcp_in_fastopen = TRUE;
2484 }
2485 else
2486 # endif
2487 if (tinfo.tcpi_state == TCP_SYN_RECV) /* Not seen on FreeBSD 12.1 */
2488 {
2489 DEBUG(D_receive)
2490 debug_printf("TFO mode connection (state TCP_SYN_RECV)\n");
2491 f.tcp_in_fastopen = TRUE;
2492 }
2493 else DEBUG(D_receive)
2494 debug_printf("TCP_INFO getsockopt: %s\n", strerror(errno));
2495 # endif
2496 }
2497 #endif
2498
2499
2500 /*************************************************
2501 * Start an SMTP session *
2502 *************************************************/
2503
2504 /* This function is called at the start of an SMTP session. Thereafter,
2505 smtp_setup_msg() is called to initiate each separate message. This
2506 function does host-specific testing, and outputs the banner line.
2507
2508 Arguments: none
2509 Returns: FALSE if the session can not continue; something has
2510 gone wrong, or the connection to the host is blocked
2511 */
2512
2513 BOOL
smtp_start_session(void)2514 smtp_start_session(void)
2515 {
2516 int esclen;
2517 uschar *user_msg, *log_msg;
2518 uschar *code, *esc;
2519 uschar *p, *s;
2520 gstring * ss;
2521
2522 gettimeofday(&smtp_connection_start, NULL);
2523 for (smtp_ch_index = 0; smtp_ch_index < SMTP_HBUFF_SIZE; smtp_ch_index++)
2524 smtp_connection_had[smtp_ch_index] = SCH_NONE;
2525 smtp_ch_index = 0;
2526
2527 /* Default values for certain variables */
2528
2529 fl.helo_seen = fl.esmtp = fl.helo_accept_junk = FALSE;
2530 smtp_mailcmd_count = 0;
2531 count_nonmail = TRUE_UNSET;
2532 synprot_error_count = unknown_command_count = nonmail_command_count = 0;
2533 smtp_delay_mail = smtp_rlm_base;
2534 fl.auth_advertised = FALSE;
2535 f.smtp_in_pipelining_advertised = f.smtp_in_pipelining_used = FALSE;
2536 f.pipelining_enable = TRUE;
2537 sync_cmd_limit = NON_SYNC_CMD_NON_PIPELINING;
2538 fl.smtp_exit_function_called = FALSE; /* For avoiding loop in not-quit exit */
2539
2540 /* If receiving by -bs from a trusted user, or testing with -bh, we allow
2541 authentication settings from -oMaa to remain in force. */
2542
2543 if (!host_checking && !f.sender_host_notsocket)
2544 sender_host_auth_pubname = sender_host_authenticated = NULL;
2545 authenticated_by = NULL;
2546
2547 #ifndef DISABLE_TLS
2548 tls_in.ver = tls_in.cipher = tls_in.peerdn = NULL;
2549 tls_in.ourcert = tls_in.peercert = NULL;
2550 tls_in.sni = NULL;
2551 tls_in.ocsp = OCSP_NOT_REQ;
2552 fl.tls_advertised = FALSE;
2553 #endif
2554 fl.dsn_advertised = FALSE;
2555 #ifdef SUPPORT_I18N
2556 fl.smtputf8_advertised = FALSE;
2557 #endif
2558
2559 /* Reset ACL connection variables */
2560
2561 acl_var_c = NULL;
2562
2563 /* Allow for trailing 0 in the command and data buffers. Tainted. */
2564
2565 smtp_cmd_buffer = store_get_perm(2*SMTP_CMD_BUFFER_SIZE + 2, TRUE);
2566
2567 smtp_cmd_buffer[0] = 0;
2568 smtp_data_buffer = smtp_cmd_buffer + SMTP_CMD_BUFFER_SIZE + 1;
2569
2570 /* For batched input, the protocol setting can be overridden from the
2571 command line by a trusted caller. */
2572
2573 if (smtp_batched_input)
2574 {
2575 if (!received_protocol) received_protocol = US"local-bsmtp";
2576 }
2577
2578 /* For non-batched SMTP input, the protocol setting is forced here. It will be
2579 reset later if any of EHLO/AUTH/STARTTLS are received. */
2580
2581 else
2582 received_protocol =
2583 (sender_host_address ? protocols : protocols_local) [pnormal];
2584
2585 /* Set up the buffer for inputting using direct read() calls, and arrange to
2586 call the local functions instead of the standard C ones. Place a NUL at the
2587 end of the buffer to safety-stop C-string reads from it. */
2588
2589 if (!(smtp_inbuffer = US malloc(IN_BUFFER_SIZE)))
2590 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "malloc() failed for SMTP input buffer");
2591 smtp_inbuffer[IN_BUFFER_SIZE-1] = '\0';
2592
2593 receive_getc = smtp_getc;
2594 receive_getbuf = smtp_getbuf;
2595 receive_get_cache = smtp_get_cache;
2596 receive_hasc = smtp_hasc;
2597 receive_ungetc = smtp_ungetc;
2598 receive_feof = smtp_feof;
2599 receive_ferror = smtp_ferror;
2600 receive_smtp_buffered = smtp_buffered;
2601 lwr_receive_getc = NULL;
2602 lwr_receive_getbuf = NULL;
2603 lwr_receive_hasc = NULL;
2604 lwr_receive_ungetc = NULL;
2605 smtp_inptr = smtp_inend = smtp_inbuffer;
2606 smtp_had_eof = smtp_had_error = 0;
2607
2608 /* Set up the message size limit; this may be host-specific */
2609
2610 thismessage_size_limit = expand_string_integer(message_size_limit, TRUE);
2611 if (expand_string_message)
2612 {
2613 if (thismessage_size_limit == -1)
2614 log_write(0, LOG_MAIN|LOG_PANIC, "unable to expand message_size_limit: "
2615 "%s", expand_string_message);
2616 else
2617 log_write(0, LOG_MAIN|LOG_PANIC, "invalid message_size_limit: "
2618 "%s", expand_string_message);
2619 smtp_closedown(US"Temporary local problem - please try later");
2620 return FALSE;
2621 }
2622
2623 /* When a message is input locally via the -bs or -bS options, sender_host_
2624 unknown is set unless -oMa was used to force an IP address, in which case it
2625 is checked like a real remote connection. When -bs is used from inetd, this
2626 flag is not set, causing the sending host to be checked. The code that deals
2627 with IP source routing (if configured) is never required for -bs or -bS and
2628 the flag sender_host_notsocket is used to suppress it.
2629
2630 If smtp_accept_max and smtp_accept_reserve are set, keep some connections in
2631 reserve for certain hosts and/or networks. */
2632
2633 if (!f.sender_host_unknown)
2634 {
2635 int rc;
2636 BOOL reserved_host = FALSE;
2637
2638 /* Look up IP options (source routing info) on the socket if this is not an
2639 -oMa "host", and if any are found, log them and drop the connection.
2640
2641 Linux (and others now, see below) is different to everyone else, so there
2642 has to be some conditional compilation here. Versions of Linux before 2.1.15
2643 used a structure whose name was "options". Somebody finally realized that
2644 this name was silly, and it got changed to "ip_options". I use the
2645 newer name here, but there is a fudge in the script that sets up os.h
2646 to define a macro in older Linux systems.
2647
2648 Sigh. Linux is a fast-moving target. Another generation of Linux uses
2649 glibc 2, which has chosen ip_opts for the structure name. This is now
2650 really a glibc thing rather than a Linux thing, so the condition name
2651 has been changed to reflect this. It is relevant also to GNU/Hurd.
2652
2653 Mac OS 10.x (Darwin) is like the later glibc versions, but without the
2654 setting of the __GLIBC__ macro, so we can't detect it automatically. There's
2655 a special macro defined in the os.h file.
2656
2657 Some DGUX versions on older hardware appear not to support IP options at
2658 all, so there is now a general macro which can be set to cut out this
2659 support altogether.
2660
2661 How to do this properly in IPv6 is not yet known. */
2662
2663 #if !HAVE_IPV6 && !defined(NO_IP_OPTIONS)
2664
2665 #ifdef GLIBC_IP_OPTIONS
2666 #if (!defined __GLIBC__) || (__GLIBC__ < 2)
2667 #define OPTSTYLE 1
2668 #else
2669 #define OPTSTYLE 2
2670 #endif
2671 #elif defined DARWIN_IP_OPTIONS
2672 #define OPTSTYLE 2
2673 #else
2674 #define OPTSTYLE 3
2675 #endif
2676
2677 if (!host_checking && !f.sender_host_notsocket)
2678 {
2679 #if OPTSTYLE == 1
2680 EXIM_SOCKLEN_T optlen = sizeof(struct ip_options) + MAX_IPOPTLEN;
2681 struct ip_options *ipopt = store_get(optlen, FALSE);
2682 #elif OPTSTYLE == 2
2683 struct ip_opts ipoptblock;
2684 struct ip_opts *ipopt = &ipoptblock;
2685 EXIM_SOCKLEN_T optlen = sizeof(ipoptblock);
2686 #else
2687 struct ipoption ipoptblock;
2688 struct ipoption *ipopt = &ipoptblock;
2689 EXIM_SOCKLEN_T optlen = sizeof(ipoptblock);
2690 #endif
2691
2692 /* Occasional genuine failures of getsockopt() have been seen - for
2693 example, "reset by peer". Therefore, just log and give up on this
2694 call, unless the error is ENOPROTOOPT. This error is given by systems
2695 that have the interfaces but not the mechanism - e.g. GNU/Hurd at the time
2696 of writing. So for that error, carry on - we just can't do an IP options
2697 check. */
2698
2699 DEBUG(D_receive) debug_printf("checking for IP options\n");
2700
2701 if (getsockopt(fileno(smtp_out), IPPROTO_IP, IP_OPTIONS, US (ipopt),
2702 &optlen) < 0)
2703 {
2704 if (errno != ENOPROTOOPT)
2705 {
2706 log_write(0, LOG_MAIN, "getsockopt() failed from %s: %s",
2707 host_and_ident(FALSE), strerror(errno));
2708 smtp_printf("451 SMTP service not available\r\n", FALSE);
2709 return FALSE;
2710 }
2711 }
2712
2713 /* Deal with any IP options that are set. On the systems I have looked at,
2714 the value of MAX_IPOPTLEN has been 40, meaning that there should never be
2715 more logging data than will fit in big_buffer. Nevertheless, after somebody
2716 questioned this code, I've added in some paranoid checking. */
2717
2718 else if (optlen > 0)
2719 {
2720 uschar *p = big_buffer;
2721 uschar *pend = big_buffer + big_buffer_size;
2722 uschar *adptr;
2723 int optcount;
2724 struct in_addr addr;
2725
2726 #if OPTSTYLE == 1
2727 uschar *optstart = US (ipopt->__data);
2728 #elif OPTSTYLE == 2
2729 uschar *optstart = US (ipopt->ip_opts);
2730 #else
2731 uschar *optstart = US (ipopt->ipopt_list);
2732 #endif
2733
2734 DEBUG(D_receive) debug_printf("IP options exist\n");
2735
2736 Ustrcpy(p, "IP options on incoming call:");
2737 p += Ustrlen(p);
2738
2739 for (uschar * opt = optstart; opt && opt < US (ipopt) + optlen; )
2740 switch (*opt)
2741 {
2742 case IPOPT_EOL:
2743 opt = NULL;
2744 break;
2745
2746 case IPOPT_NOP:
2747 opt++;
2748 break;
2749
2750 case IPOPT_SSRR:
2751 case IPOPT_LSRR:
2752 if (!string_format(p, pend-p, " %s [@%s",
2753 (*opt == IPOPT_SSRR)? "SSRR" : "LSRR",
2754 #if OPTSTYLE == 1
2755 inet_ntoa(*((struct in_addr *)(&(ipopt->faddr))))))
2756 #elif OPTSTYLE == 2
2757 inet_ntoa(ipopt->ip_dst)))
2758 #else
2759 inet_ntoa(ipopt->ipopt_dst)))
2760 #endif
2761 {
2762 opt = NULL;
2763 break;
2764 }
2765
2766 p += Ustrlen(p);
2767 optcount = (opt[1] - 3) / sizeof(struct in_addr);
2768 adptr = opt + 3;
2769 while (optcount-- > 0)
2770 {
2771 memcpy(&addr, adptr, sizeof(addr));
2772 if (!string_format(p, pend - p - 1, "%s%s",
2773 (optcount == 0)? ":" : "@", inet_ntoa(addr)))
2774 {
2775 opt = NULL;
2776 break;
2777 }
2778 p += Ustrlen(p);
2779 adptr += sizeof(struct in_addr);
2780 }
2781 *p++ = ']';
2782 opt += opt[1];
2783 break;
2784
2785 default:
2786 {
2787 if (pend - p < 4 + 3*opt[1]) { opt = NULL; break; }
2788 Ustrcat(p, "[ ");
2789 p += 2;
2790 for (int i = 0; i < opt[1]; i++)
2791 p += sprintf(CS p, "%2.2x ", opt[i]);
2792 *p++ = ']';
2793 }
2794 opt += opt[1];
2795 break;
2796 }
2797
2798 *p = 0;
2799 log_write(0, LOG_MAIN, "%s", big_buffer);
2800
2801 /* Refuse any call with IP options. This is what tcpwrappers 7.5 does. */
2802
2803 log_write(0, LOG_MAIN|LOG_REJECT,
2804 "connection from %s refused (IP options)", host_and_ident(FALSE));
2805
2806 smtp_printf("554 SMTP service not available\r\n", FALSE);
2807 return FALSE;
2808 }
2809
2810 /* Length of options = 0 => there are no options */
2811
2812 else DEBUG(D_receive) debug_printf("no IP options found\n");
2813 }
2814 #endif /* HAVE_IPV6 && !defined(NO_IP_OPTIONS) */
2815
2816 /* Set keep-alive in socket options. The option is on by default. This
2817 setting is an attempt to get rid of some hanging connections that stick in
2818 read() when the remote end (usually a dialup) goes away. */
2819
2820 if (smtp_accept_keepalive && !f.sender_host_notsocket)
2821 ip_keepalive(fileno(smtp_out), sender_host_address, FALSE);
2822
2823 /* If the current host matches host_lookup, set the name by doing a
2824 reverse lookup. On failure, sender_host_name will be NULL and
2825 host_lookup_failed will be TRUE. This may or may not be serious - optional
2826 checks later. */
2827
2828 if (verify_check_host(&host_lookup) == OK)
2829 {
2830 (void)host_name_lookup();
2831 host_build_sender_fullhost();
2832 }
2833
2834 /* Delay this until we have the full name, if it is looked up. */
2835
2836 set_process_info("handling incoming connection from %s",
2837 host_and_ident(FALSE));
2838
2839 /* Expand smtp_receive_timeout, if needed */
2840
2841 if (smtp_receive_timeout_s)
2842 {
2843 uschar * exp;
2844 if ( !(exp = expand_string(smtp_receive_timeout_s))
2845 || !(*exp)
2846 || (smtp_receive_timeout = readconf_readtime(exp, 0, FALSE)) < 0
2847 )
2848 log_write(0, LOG_MAIN|LOG_PANIC,
2849 "bad value for smtp_receive_timeout: '%s'", exp ? exp : US"");
2850 }
2851
2852 /* Test for explicit connection rejection */
2853
2854 if (verify_check_host(&host_reject_connection) == OK)
2855 {
2856 log_write(L_connection_reject, LOG_MAIN|LOG_REJECT, "refused connection "
2857 "from %s (host_reject_connection)", host_and_ident(FALSE));
2858 smtp_printf("554 SMTP service not available\r\n", FALSE);
2859 return FALSE;
2860 }
2861
2862 /* Test with TCP Wrappers if so configured. There is a problem in that
2863 hosts_ctl() returns 0 (deny) under a number of system failure circumstances,
2864 such as disks dying. In these cases, it is desirable to reject with a 4xx
2865 error instead of a 5xx error. There isn't a "right" way to detect such
2866 problems. The following kludge is used: errno is zeroed before calling
2867 hosts_ctl(). If the result is "reject", a 5xx error is given only if the
2868 value of errno is 0 or ENOENT (which happens if /etc/hosts.{allow,deny} does
2869 not exist). */
2870
2871 #ifdef USE_TCP_WRAPPERS
2872 errno = 0;
2873 if (!(tcp_wrappers_name = expand_string(tcp_wrappers_daemon_name)))
2874 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "Expansion of \"%s\" "
2875 "(tcp_wrappers_name) failed: %s", string_printing(tcp_wrappers_name),
2876 expand_string_message);
2877 request_init(&tcpwrap_ri,
2878 RQ_DAEMON, tcp_wrappers_name,
2879 RQ_FILE, fileno(smtp_out),
2880 RQ_CLIENT_NAME, (sender_host_name == NULL)? STRING_UNKNOWN : CS sender_host_name,
2881 RQ_CLIENT_ADDR, (sender_host_address == NULL)? STRING_UNKNOWN : CS sender_host_address,
2882 RQ_USER, (sender_ident == NULL)? STRING_UNKNOWN : CS sender_ident,
2883 0);
2884 if (!hosts_access(&tcpwrap_ri))
2885 {
2886 if (errno == 0 || errno == ENOENT)
2887 {
2888 HDEBUG(D_receive) debug_printf("tcp wrappers rejection\n");
2889 log_write(L_connection_reject,
2890 LOG_MAIN|LOG_REJECT, "refused connection from %s "
2891 "(tcp wrappers)", host_and_ident(FALSE));
2892 smtp_printf("554 SMTP service not available\r\n", FALSE);
2893 }
2894 else
2895 {
2896 int save_errno = errno;
2897 HDEBUG(D_receive) debug_printf("tcp wrappers rejected with unexpected "
2898 "errno value %d\n", save_errno);
2899 log_write(L_connection_reject,
2900 LOG_MAIN|LOG_REJECT, "temporarily refused connection from %s "
2901 "(tcp wrappers errno=%d)", host_and_ident(FALSE), save_errno);
2902 smtp_printf("451 Temporary local problem - please try later\r\n", FALSE);
2903 }
2904 return FALSE;
2905 }
2906 #endif
2907
2908 /* Check for reserved slots. The value of smtp_accept_count has already been
2909 incremented to include this process. */
2910
2911 if (smtp_accept_max > 0 &&
2912 smtp_accept_count > smtp_accept_max - smtp_accept_reserve)
2913 {
2914 if ((rc = verify_check_host(&smtp_reserve_hosts)) != OK)
2915 {
2916 log_write(L_connection_reject,
2917 LOG_MAIN, "temporarily refused connection from %s: not in "
2918 "reserve list: connected=%d max=%d reserve=%d%s",
2919 host_and_ident(FALSE), smtp_accept_count - 1, smtp_accept_max,
2920 smtp_accept_reserve, (rc == DEFER)? " (lookup deferred)" : "");
2921 smtp_printf("421 %s: Too many concurrent SMTP connections; "
2922 "please try again later\r\n", FALSE, smtp_active_hostname);
2923 return FALSE;
2924 }
2925 reserved_host = TRUE;
2926 }
2927
2928 /* If a load level above which only messages from reserved hosts are
2929 accepted is set, check the load. For incoming calls via the daemon, the
2930 check is done in the superior process if there are no reserved hosts, to
2931 save a fork. In all cases, the load average will already be available
2932 in a global variable at this point. */
2933
2934 if (smtp_load_reserve >= 0 &&
2935 load_average > smtp_load_reserve &&
2936 !reserved_host &&
2937 verify_check_host(&smtp_reserve_hosts) != OK)
2938 {
2939 log_write(L_connection_reject,
2940 LOG_MAIN, "temporarily refused connection from %s: not in "
2941 "reserve list and load average = %.2f", host_and_ident(FALSE),
2942 (double)load_average/1000.0);
2943 smtp_printf("421 %s: Too much load; please try again later\r\n", FALSE,
2944 smtp_active_hostname);
2945 return FALSE;
2946 }
2947
2948 /* Determine whether unqualified senders or recipients are permitted
2949 for this host. Unfortunately, we have to do this every time, in order to
2950 set the flags so that they can be inspected when considering qualifying
2951 addresses in the headers. For a site that permits no qualification, this
2952 won't take long, however. */
2953
2954 f.allow_unqualified_sender =
2955 verify_check_host(&sender_unqualified_hosts) == OK;
2956
2957 f.allow_unqualified_recipient =
2958 verify_check_host(&recipient_unqualified_hosts) == OK;
2959
2960 /* Determine whether HELO/EHLO is required for this host. The requirement
2961 can be hard or soft. */
2962
2963 fl.helo_verify_required = verify_check_host(&helo_verify_hosts) == OK;
2964 if (!fl.helo_verify_required)
2965 fl.helo_verify = verify_check_host(&helo_try_verify_hosts) == OK;
2966
2967 /* Determine whether this hosts is permitted to send syntactic junk
2968 after a HELO or EHLO command. */
2969
2970 fl.helo_accept_junk = verify_check_host(&helo_accept_junk_hosts) == OK;
2971 }
2972
2973 /* For batch SMTP input we are now done. */
2974
2975 if (smtp_batched_input) return TRUE;
2976
2977 /* If valid Proxy Protocol source is connecting, set up session.
2978 Failure will not allow any SMTP function other than QUIT. */
2979
2980 #ifdef SUPPORT_PROXY
2981 proxy_session = FALSE;
2982 f.proxy_session_failed = FALSE;
2983 if (check_proxy_protocol_host())
2984 setup_proxy_protocol_host();
2985 #endif
2986
2987 /* Start up TLS if tls_on_connect is set. This is for supporting the legacy
2988 smtps port for use with older style SSL MTAs. */
2989
2990 #ifndef DISABLE_TLS
2991 if (tls_in.on_connect)
2992 {
2993 if (tls_server_start(&user_msg) != OK)
2994 return smtp_log_tls_fail(user_msg);
2995 cmd_list[CMD_LIST_TLS_AUTH].is_mail_cmd = TRUE;
2996 }
2997 #endif
2998
2999 /* Run the connect ACL if it exists */
3000
3001 user_msg = NULL;
3002 if (acl_smtp_connect)
3003 {
3004 int rc;
3005 if ((rc = acl_check(ACL_WHERE_CONNECT, NULL, acl_smtp_connect, &user_msg,
3006 &log_msg)) != OK)
3007 {
3008 (void) smtp_handle_acl_fail(ACL_WHERE_CONNECT, rc, user_msg, log_msg);
3009 return FALSE;
3010 }
3011 }
3012
3013 /* Output the initial message for a two-way SMTP connection. It may contain
3014 newlines, which then cause a multi-line response to be given. */
3015
3016 code = US"220"; /* Default status code */
3017 esc = US""; /* Default extended status code */
3018 esclen = 0; /* Length of esc */
3019
3020 if (!user_msg)
3021 {
3022 if (!(s = expand_string(smtp_banner)))
3023 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "Expansion of \"%s\" (smtp_banner) "
3024 "failed: %s", smtp_banner, expand_string_message);
3025 }
3026 else
3027 {
3028 int codelen = 3;
3029 s = user_msg;
3030 smtp_message_code(&code, &codelen, &s, NULL, TRUE);
3031 if (codelen > 4)
3032 {
3033 esc = code + 4;
3034 esclen = codelen - 4;
3035 }
3036 }
3037
3038 /* Remove any terminating newlines; might as well remove trailing space too */
3039
3040 p = s + Ustrlen(s);
3041 while (p > s && isspace(p[-1])) p--;
3042 s = string_copyn(s, p-s);
3043
3044 /* It seems that CC:Mail is braindead, and assumes that the greeting message
3045 is all contained in a single IP packet. The original code wrote out the
3046 greeting using several calls to fprint/fputc, and on busy servers this could
3047 cause it to be split over more than one packet - which caused CC:Mail to fall
3048 over when it got the second part of the greeting after sending its first
3049 command. Sigh. To try to avoid this, build the complete greeting message
3050 first, and output it in one fell swoop. This gives a better chance of it
3051 ending up as a single packet. */
3052
3053 ss = string_get(256);
3054
3055 p = s;
3056 do /* At least once, in case we have an empty string */
3057 {
3058 int len;
3059 uschar *linebreak = Ustrchr(p, '\n');
3060 ss = string_catn(ss, code, 3);
3061 if (!linebreak)
3062 {
3063 len = Ustrlen(p);
3064 ss = string_catn(ss, US" ", 1);
3065 }
3066 else
3067 {
3068 len = linebreak - p;
3069 ss = string_catn(ss, US"-", 1);
3070 }
3071 ss = string_catn(ss, esc, esclen);
3072 ss = string_catn(ss, p, len);
3073 ss = string_catn(ss, US"\r\n", 2);
3074 p += len;
3075 if (linebreak) p++;
3076 }
3077 while (*p);
3078
3079 /* Before we write the banner, check that there is no input pending, unless
3080 this synchronisation check is disabled. */
3081
3082 #ifndef DISABLE_PIPE_CONNECT
3083 fl.pipe_connect_acceptable =
3084 sender_host_address && verify_check_host(&pipe_connect_advertise_hosts) == OK;
3085
3086 if (!check_sync())
3087 if (fl.pipe_connect_acceptable)
3088 f.smtp_in_early_pipe_used = TRUE;
3089 else
3090 #else
3091 if (!check_sync())
3092 #endif
3093 {
3094 unsigned n = smtp_inend - smtp_inptr;
3095 if (n > 128) n = 128;
3096
3097 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP protocol "
3098 "synchronization error (input sent without waiting for greeting): "
3099 "rejected connection from %s input=\"%s\"", host_and_ident(TRUE),
3100 string_printing(string_copyn(smtp_inptr, n)));
3101 smtp_printf("554 SMTP synchronization error\r\n", FALSE);
3102 return FALSE;
3103 }
3104
3105 /* Now output the banner */
3106 /*XXX the ehlo-resp code does its own tls/nontls bit. Maybe subroutine that? */
3107
3108 smtp_printf("%s",
3109 #ifndef DISABLE_PIPE_CONNECT
3110 fl.pipe_connect_acceptable && pipeline_connect_sends(),
3111 #else
3112 FALSE,
3113 #endif
3114 string_from_gstring(ss));
3115
3116 /* Attempt to see if we sent the banner before the last ACK of the 3-way
3117 handshake arrived. If so we must have managed a TFO. */
3118
3119 #ifdef TCP_FASTOPEN
3120 if (sender_host_address && !f.sender_host_notsocket) tfo_in_check();
3121 #endif
3122
3123 return TRUE;
3124 }
3125
3126
3127
3128
3129
3130 /*************************************************
3131 * Handle SMTP syntax and protocol errors *
3132 *************************************************/
3133
3134 /* Write to the log for SMTP syntax errors in incoming commands, if configured
3135 to do so. Then transmit the error response. The return value depends on the
3136 number of syntax and protocol errors in this SMTP session.
3137
3138 Arguments:
3139 type error type, given as a log flag bit
3140 code response code; <= 0 means don't send a response
3141 data data to reflect in the response (can be NULL)
3142 errmess the error message
3143
3144 Returns: -1 limit of syntax/protocol errors NOT exceeded
3145 +1 limit of syntax/protocol errors IS exceeded
3146
3147 These values fit in with the values of the "done" variable in the main
3148 processing loop in smtp_setup_msg(). */
3149
3150 static int
synprot_error(int type,int code,uschar * data,uschar * errmess)3151 synprot_error(int type, int code, uschar *data, uschar *errmess)
3152 {
3153 int yield = -1;
3154
3155 log_write(type, LOG_MAIN, "SMTP %s error in \"%s\" %s %s",
3156 type == L_smtp_syntax_error ? "syntax" : "protocol",
3157 string_printing(smtp_cmd_buffer), host_and_ident(TRUE), errmess);
3158
3159 if (++synprot_error_count > smtp_max_synprot_errors)
3160 {
3161 yield = 1;
3162 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
3163 "syntax or protocol errors (last command was \"%s\", %s)",
3164 host_and_ident(FALSE), string_printing(smtp_cmd_buffer),
3165 string_from_gstring(s_connhad_log(NULL))
3166 );
3167 }
3168
3169 if (code > 0)
3170 {
3171 smtp_printf("%d%c%s%s%s\r\n", FALSE, code, yield == 1 ? '-' : ' ',
3172 data ? data : US"", data ? US": " : US"", errmess);
3173 if (yield == 1)
3174 smtp_printf("%d Too many syntax or protocol errors\r\n", FALSE, code);
3175 }
3176
3177 return yield;
3178 }
3179
3180
3181
3182
3183 /*************************************************
3184 * Send SMTP response, possibly multiline *
3185 *************************************************/
3186
3187 /* There are, it seems, broken clients out there that cannot handle multiline
3188 responses. If no_multiline_responses is TRUE (it can be set from an ACL), we
3189 output nothing for non-final calls, and only the first line for anything else.
3190
3191 Arguments:
3192 code SMTP code, may involve extended status codes
3193 codelen length of smtp code; if > 4 there's an ESC
3194 final FALSE if the last line isn't the final line
3195 msg message text, possibly containing newlines
3196
3197 Returns: nothing
3198 */
3199
3200 void
smtp_respond(uschar * code,int codelen,BOOL final,uschar * msg)3201 smtp_respond(uschar* code, int codelen, BOOL final, uschar *msg)
3202 {
3203 int esclen = 0;
3204 uschar *esc = US"";
3205
3206 if (!final && f.no_multiline_responses) return;
3207
3208 if (codelen > 4)
3209 {
3210 esc = code + 4;
3211 esclen = codelen - 4;
3212 }
3213
3214 /* If this is the first output for a (non-batch) RCPT command, see if all RCPTs
3215 have had the same. Note: this code is also present in smtp_printf(). It would
3216 be tidier to have it only in one place, but when it was added, it was easier to
3217 do it that way, so as not to have to mess with the code for the RCPT command,
3218 which sometimes uses smtp_printf() and sometimes smtp_respond(). */
3219
3220 if (fl.rcpt_in_progress)
3221 {
3222 if (!rcpt_smtp_response)
3223 rcpt_smtp_response = string_copy(msg);
3224 else if (fl.rcpt_smtp_response_same &&
3225 Ustrcmp(rcpt_smtp_response, msg) != 0)
3226 fl.rcpt_smtp_response_same = FALSE;
3227 fl.rcpt_in_progress = FALSE;
3228 }
3229
3230 /* Now output the message, splitting it up into multiple lines if necessary.
3231 We only handle pipelining these responses as far as nonfinal/final groups,
3232 not the whole MAIL/RCPT/DATA response set. */
3233
3234 for (;;)
3235 {
3236 uschar *nl = Ustrchr(msg, '\n');
3237 if (!nl)
3238 {
3239 smtp_printf("%.3s%c%.*s%s\r\n", !final, code, final ? ' ':'-', esclen, esc, msg);
3240 return;
3241 }
3242 else if (nl[1] == 0 || f.no_multiline_responses)
3243 {
3244 smtp_printf("%.3s%c%.*s%.*s\r\n", !final, code, final ? ' ':'-', esclen, esc,
3245 (int)(nl - msg), msg);
3246 return;
3247 }
3248 else
3249 {
3250 smtp_printf("%.3s-%.*s%.*s\r\n", TRUE, code, esclen, esc, (int)(nl - msg), msg);
3251 msg = nl + 1;
3252 Uskip_whitespace(&msg);
3253 }
3254 }
3255 }
3256
3257
3258
3259
3260 /*************************************************
3261 * Parse user SMTP message *
3262 *************************************************/
3263
3264 /* This function allows for user messages overriding the response code details
3265 by providing a suitable response code string at the start of the message
3266 user_msg. Check the message for starting with a response code and optionally an
3267 extended status code. If found, check that the first digit is valid, and if so,
3268 change the code pointer and length to use the replacement. An invalid code
3269 causes a panic log; in this case, if the log messages is the same as the user
3270 message, we must also adjust the value of the log message to show the code that
3271 is actually going to be used (the original one).
3272
3273 This function is global because it is called from receive.c as well as within
3274 this module.
3275
3276 Note that the code length returned includes the terminating whitespace
3277 character, which is always included in the regex match.
3278
3279 Arguments:
3280 code SMTP code, may involve extended status codes
3281 codelen length of smtp code; if > 4 there's an ESC
3282 msg message text
3283 log_msg optional log message, to be adjusted with the new SMTP code
3284 check_valid if true, verify the response code
3285
3286 Returns: nothing
3287 */
3288
3289 void
smtp_message_code(uschar ** code,int * codelen,uschar ** msg,uschar ** log_msg,BOOL check_valid)3290 smtp_message_code(uschar **code, int *codelen, uschar **msg, uschar **log_msg,
3291 BOOL check_valid)
3292 {
3293 int n;
3294 int ovector[3];
3295
3296 if (!msg || !*msg) return;
3297
3298 if ((n = pcre_exec(regex_smtp_code, NULL, CS *msg, Ustrlen(*msg), 0,
3299 PCRE_EOPT, ovector, sizeof(ovector)/sizeof(int))) < 0) return;
3300
3301 if (check_valid && (*msg)[0] != (*code)[0])
3302 {
3303 log_write(0, LOG_MAIN|LOG_PANIC, "configured error code starts with "
3304 "incorrect digit (expected %c) in \"%s\"", (*code)[0], *msg);
3305 if (log_msg != NULL && *log_msg == *msg)
3306 *log_msg = string_sprintf("%s %s", *code, *log_msg + ovector[1]);
3307 }
3308 else
3309 {
3310 *code = *msg;
3311 *codelen = ovector[1]; /* Includes final space */
3312 }
3313 *msg += ovector[1]; /* Chop the code off the message */
3314 return;
3315 }
3316
3317
3318
3319
3320 /*************************************************
3321 * Handle an ACL failure *
3322 *************************************************/
3323
3324 /* This function is called when acl_check() fails. As well as calls from within
3325 this module, it is called from receive.c for an ACL after DATA. It sorts out
3326 logging the incident, and sends the error response. A message containing
3327 newlines is turned into a multiline SMTP response, but for logging, only the
3328 first line is used.
3329
3330 There's a table of default permanent failure response codes to use in
3331 globals.c, along with the table of names. VFRY is special. Despite RFC1123 it
3332 defaults disabled in Exim. However, discussion in connection with RFC 821bis
3333 (aka RFC 2821) has concluded that the response should be 252 in the disabled
3334 state, because there are broken clients that try VRFY before RCPT. A 5xx
3335 response should be given only when the address is positively known to be
3336 undeliverable. Sigh. We return 252 if there is no VRFY ACL or it provides
3337 no explicit code, but if there is one we let it know best.
3338 Also, for ETRN, 458 is given on refusal, and for AUTH, 503.
3339
3340 From Exim 4.63, it is possible to override the response code details by
3341 providing a suitable response code string at the start of the message provided
3342 in user_msg. The code's first digit is checked for validity.
3343
3344 Arguments:
3345 where where the ACL was called from
3346 rc the failure code
3347 user_msg a message that can be included in an SMTP response
3348 log_msg a message for logging
3349
3350 Returns: 0 in most cases
3351 2 if the failure code was FAIL_DROP, in which case the
3352 SMTP connection should be dropped (this value fits with the
3353 "done" variable in smtp_setup_msg() below)
3354 */
3355
3356 int
smtp_handle_acl_fail(int where,int rc,uschar * user_msg,uschar * log_msg)3357 smtp_handle_acl_fail(int where, int rc, uschar *user_msg, uschar *log_msg)
3358 {
3359 BOOL drop = rc == FAIL_DROP;
3360 int codelen = 3;
3361 uschar *smtp_code;
3362 uschar *lognl;
3363 uschar *sender_info = US"";
3364 uschar *what;
3365
3366 if (drop) rc = FAIL;
3367
3368 /* Set the default SMTP code, and allow a user message to change it. */
3369
3370 smtp_code = rc == FAIL ? acl_wherecodes[where] : US"451";
3371 smtp_message_code(&smtp_code, &codelen, &user_msg, &log_msg,
3372 where != ACL_WHERE_VRFY);
3373
3374 /* We used to have sender_address here; however, there was a bug that was not
3375 updating sender_address after a rewrite during a verify. When this bug was
3376 fixed, sender_address at this point became the rewritten address. I'm not sure
3377 this is what should be logged, so I've changed to logging the unrewritten
3378 address to retain backward compatibility. */
3379
3380 switch (where)
3381 {
3382 #ifdef WITH_CONTENT_SCAN
3383 case ACL_WHERE_MIME: what = US"during MIME ACL checks"; break;
3384 #endif
3385 case ACL_WHERE_PREDATA: what = US"DATA"; break;
3386 case ACL_WHERE_DATA: what = US"after DATA"; break;
3387 #ifndef DISABLE_PRDR
3388 case ACL_WHERE_PRDR: what = US"after DATA PRDR"; break;
3389 #endif
3390 default:
3391 {
3392 uschar * place = smtp_cmd_data ? smtp_cmd_data : US"in \"connect\" ACL";
3393 int lim = 100;
3394
3395 if (where == ACL_WHERE_AUTH) /* avoid logging auth creds */
3396 {
3397 uschar * s;
3398 for (s = smtp_cmd_data; *s && !isspace(*s); ) s++;
3399 lim = s - smtp_cmd_data; /* atop after method */
3400 }
3401 what = string_sprintf("%s %.*s", acl_wherenames[where], lim, place);
3402 }
3403 }
3404 switch (where)
3405 {
3406 case ACL_WHERE_RCPT:
3407 case ACL_WHERE_DATA:
3408 #ifdef WITH_CONTENT_SCAN
3409 case ACL_WHERE_MIME:
3410 #endif
3411 sender_info = string_sprintf("F=<%s>%s%s%s%s ",
3412 sender_address_unrewritten ? sender_address_unrewritten : sender_address,
3413 sender_host_authenticated ? US" A=" : US"",
3414 sender_host_authenticated ? sender_host_authenticated : US"",
3415 sender_host_authenticated && authenticated_id ? US":" : US"",
3416 sender_host_authenticated && authenticated_id ? authenticated_id : US""
3417 );
3418 break;
3419 }
3420
3421 /* If there's been a sender verification failure with a specific message, and
3422 we have not sent a response about it yet, do so now, as a preliminary line for
3423 failures, but not defers. However, always log it for defer, and log it for fail
3424 unless the sender_verify_fail log selector has been turned off. */
3425
3426 if (sender_verified_failed &&
3427 !testflag(sender_verified_failed, af_sverify_told))
3428 {
3429 BOOL save_rcpt_in_progress = fl.rcpt_in_progress;
3430 fl.rcpt_in_progress = FALSE; /* So as not to treat these as the error */
3431
3432 setflag(sender_verified_failed, af_sverify_told);
3433
3434 if (rc != FAIL || LOGGING(sender_verify_fail))
3435 log_write(0, LOG_MAIN|LOG_REJECT, "%s sender verify %s for <%s>%s",
3436 host_and_ident(TRUE),
3437 ((sender_verified_failed->special_action & 255) == DEFER)? "defer":"fail",
3438 sender_verified_failed->address,
3439 (sender_verified_failed->message == NULL)? US"" :
3440 string_sprintf(": %s", sender_verified_failed->message));
3441
3442 if (rc == FAIL && sender_verified_failed->user_message)
3443 smtp_respond(smtp_code, codelen, FALSE, string_sprintf(
3444 testflag(sender_verified_failed, af_verify_pmfail)?
3445 "Postmaster verification failed while checking <%s>\n%s\n"
3446 "Several RFCs state that you are required to have a postmaster\n"
3447 "mailbox for each mail domain. This host does not accept mail\n"
3448 "from domains whose servers reject the postmaster address."
3449 :
3450 testflag(sender_verified_failed, af_verify_nsfail)?
3451 "Callback setup failed while verifying <%s>\n%s\n"
3452 "The initial connection, or a HELO or MAIL FROM:<> command was\n"
3453 "rejected. Refusing MAIL FROM:<> does not help fight spam, disregards\n"
3454 "RFC requirements, and stops you from receiving standard bounce\n"
3455 "messages. This host does not accept mail from domains whose servers\n"
3456 "refuse bounces."
3457 :
3458 "Verification failed for <%s>\n%s",
3459 sender_verified_failed->address,
3460 sender_verified_failed->user_message));
3461
3462 fl.rcpt_in_progress = save_rcpt_in_progress;
3463 }
3464
3465 /* Sort out text for logging */
3466
3467 log_msg = log_msg ? string_sprintf(": %s", log_msg) : US"";
3468 if ((lognl = Ustrchr(log_msg, '\n'))) *lognl = 0;
3469
3470 /* Send permanent failure response to the command, but the code used isn't
3471 always a 5xx one - see comments at the start of this function. If the original
3472 rc was FAIL_DROP we drop the connection and yield 2. */
3473
3474 if (rc == FAIL)
3475 smtp_respond(smtp_code, codelen, TRUE,
3476 user_msg ? user_msg : US"Administrative prohibition");
3477
3478 /* Send temporary failure response to the command. Don't give any details,
3479 unless acl_temp_details is set. This is TRUE for a callout defer, a "defer"
3480 verb, and for a header verify when smtp_return_error_details is set.
3481
3482 This conditional logic is all somewhat of a mess because of the odd
3483 interactions between temp_details and return_error_details. One day it should
3484 be re-implemented in a tidier fashion. */
3485
3486 else
3487 if (f.acl_temp_details && user_msg)
3488 {
3489 if ( smtp_return_error_details
3490 && sender_verified_failed
3491 && sender_verified_failed->message
3492 )
3493 smtp_respond(smtp_code, codelen, FALSE, sender_verified_failed->message);
3494
3495 smtp_respond(smtp_code, codelen, TRUE, user_msg);
3496 }
3497 else
3498 smtp_respond(smtp_code, codelen, TRUE,
3499 US"Temporary local problem - please try later");
3500
3501 /* Log the incident to the logs that are specified by log_reject_target
3502 (default main, reject). This can be empty to suppress logging of rejections. If
3503 the connection is not forcibly to be dropped, return 0. Otherwise, log why it
3504 is closing if required and return 2. */
3505
3506 if (log_reject_target != 0)
3507 {
3508 #ifndef DISABLE_TLS
3509 gstring * g = s_tlslog(NULL);
3510 uschar * tls = string_from_gstring(g);
3511 if (!tls) tls = US"";
3512 #else
3513 uschar * tls = US"";
3514 #endif
3515 log_write(where == ACL_WHERE_CONNECT ? L_connection_reject : 0,
3516 log_reject_target, "%s%s%s %s%srejected %s%s",
3517 LOGGING(dnssec) && sender_host_dnssec ? US" DS" : US"",
3518 host_and_ident(TRUE),
3519 tls,
3520 sender_info,
3521 rc == FAIL ? US"" : US"temporarily ",
3522 what, log_msg);
3523 }
3524
3525 if (!drop) return 0;
3526
3527 log_write(L_smtp_connection, LOG_MAIN, "%s closed by DROP in ACL",
3528 smtp_get_connection_info());
3529
3530 /* Run the not-quit ACL, but without any custom messages. This should not be a
3531 problem, because we get here only if some other ACL has issued "drop", and
3532 in that case, *its* custom messages will have been used above. */
3533
3534 smtp_notquit_exit(US"acl-drop", NULL, NULL);
3535 return 2;
3536 }
3537
3538
3539
3540
3541 /*************************************************
3542 * Handle SMTP exit when QUIT is not given *
3543 *************************************************/
3544
3545 /* This function provides a logging/statistics hook for when an SMTP connection
3546 is dropped on the floor or the other end goes away. It's a global function
3547 because it's called from receive.c as well as this module. As well as running
3548 the NOTQUIT ACL, if there is one, this function also outputs a final SMTP
3549 response, either with a custom message from the ACL, or using a default. There
3550 is one case, however, when no message is output - after "drop". In that case,
3551 the ACL that obeyed "drop" has already supplied the custom message, and NULL is
3552 passed to this function.
3553
3554 In case things go wrong while processing this function, causing an error that
3555 may re-enter this function, there is a recursion check.
3556
3557 Arguments:
3558 reason What $smtp_notquit_reason will be set to in the ACL;
3559 if NULL, the ACL is not run
3560 code The error code to return as part of the response
3561 defaultrespond The default message if there's no user_msg
3562
3563 Returns: Nothing
3564 */
3565
3566 void
smtp_notquit_exit(uschar * reason,uschar * code,uschar * defaultrespond,...)3567 smtp_notquit_exit(uschar *reason, uschar *code, uschar *defaultrespond, ...)
3568 {
3569 int rc;
3570 uschar *user_msg = NULL;
3571 uschar *log_msg = NULL;
3572
3573 /* Check for recursive call */
3574
3575 if (fl.smtp_exit_function_called)
3576 {
3577 log_write(0, LOG_PANIC, "smtp_notquit_exit() called more than once (%s)",
3578 reason);
3579 return;
3580 }
3581 fl.smtp_exit_function_called = TRUE;
3582
3583 /* Call the not-QUIT ACL, if there is one, unless no reason is given. */
3584
3585 if (acl_smtp_notquit && reason)
3586 {
3587 smtp_notquit_reason = reason;
3588 if ((rc = acl_check(ACL_WHERE_NOTQUIT, NULL, acl_smtp_notquit, &user_msg,
3589 &log_msg)) == ERROR)
3590 log_write(0, LOG_MAIN|LOG_PANIC, "ACL for not-QUIT returned ERROR: %s",
3591 log_msg);
3592 }
3593
3594 /* If the connection was dropped, we certainly are no longer talking TLS */
3595 tls_in.active.sock = -1;
3596
3597 /* Write an SMTP response if we are expected to give one. As the default
3598 responses are all internal, they should be reasonable size. */
3599
3600 if (code && defaultrespond)
3601 {
3602 if (user_msg)
3603 smtp_respond(code, 3, TRUE, user_msg);
3604 else
3605 {
3606 gstring * g;
3607 va_list ap;
3608
3609 va_start(ap, defaultrespond);
3610 g = string_vformat(NULL, SVFMT_EXTEND|SVFMT_REBUFFER, CS defaultrespond, ap);
3611 va_end(ap);
3612 smtp_printf("%s %s\r\n", FALSE, code, string_from_gstring(g));
3613 }
3614 mac_smtp_fflush();
3615 }
3616 }
3617
3618
3619
3620
3621 /*************************************************
3622 * Verify HELO argument *
3623 *************************************************/
3624
3625 /* This function is called if helo_verify_hosts or helo_try_verify_hosts is
3626 matched. It is also called from ACL processing if verify = helo is used and
3627 verification was not previously tried (i.e. helo_try_verify_hosts was not
3628 matched). The result of its processing is to set helo_verified and
3629 helo_verify_failed. These variables should both be FALSE for this function to
3630 be called.
3631
3632 Note that EHLO/HELO is legitimately allowed to quote an address literal. Allow
3633 for IPv6 ::ffff: literals.
3634
3635 Argument: none
3636 Returns: TRUE if testing was completed;
3637 FALSE on a temporary failure
3638 */
3639
3640 BOOL
smtp_verify_helo(void)3641 smtp_verify_helo(void)
3642 {
3643 BOOL yield = TRUE;
3644
3645 HDEBUG(D_receive) debug_printf("verifying EHLO/HELO argument \"%s\"\n",
3646 sender_helo_name);
3647
3648 if (sender_helo_name == NULL)
3649 {
3650 HDEBUG(D_receive) debug_printf("no EHLO/HELO command was issued\n");
3651 }
3652
3653 /* Deal with the case of -bs without an IP address */
3654
3655 else if (sender_host_address == NULL)
3656 {
3657 HDEBUG(D_receive) debug_printf("no client IP address: assume success\n");
3658 f.helo_verified = TRUE;
3659 }
3660
3661 /* Deal with the more common case when there is a sending IP address */
3662
3663 else if (sender_helo_name[0] == '[')
3664 {
3665 f.helo_verified = Ustrncmp(sender_helo_name+1, sender_host_address,
3666 Ustrlen(sender_host_address)) == 0;
3667
3668 #if HAVE_IPV6
3669 if (!f.helo_verified)
3670 {
3671 if (strncmpic(sender_host_address, US"::ffff:", 7) == 0)
3672 f.helo_verified = Ustrncmp(sender_helo_name + 1,
3673 sender_host_address + 7, Ustrlen(sender_host_address) - 7) == 0;
3674 }
3675 #endif
3676
3677 HDEBUG(D_receive)
3678 { if (f.helo_verified) debug_printf("matched host address\n"); }
3679 }
3680
3681 /* Do a reverse lookup if one hasn't already given a positive or negative
3682 response. If that fails, or the name doesn't match, try checking with a forward
3683 lookup. */
3684
3685 else
3686 {
3687 if (sender_host_name == NULL && !host_lookup_failed)
3688 yield = host_name_lookup() != DEFER;
3689
3690 /* If a host name is known, check it and all its aliases. */
3691
3692 if (sender_host_name)
3693 if ((f.helo_verified = strcmpic(sender_host_name, sender_helo_name) == 0))
3694 {
3695 sender_helo_dnssec = sender_host_dnssec;
3696 HDEBUG(D_receive) debug_printf("matched host name\n");
3697 }
3698 else
3699 {
3700 uschar **aliases = sender_host_aliases;
3701 while (*aliases)
3702 if ((f.helo_verified = strcmpic(*aliases++, sender_helo_name) == 0))
3703 {
3704 sender_helo_dnssec = sender_host_dnssec;
3705 break;
3706 }
3707
3708 HDEBUG(D_receive) if (f.helo_verified)
3709 debug_printf("matched alias %s\n", *(--aliases));
3710 }
3711
3712 /* Final attempt: try a forward lookup of the helo name */
3713
3714 if (!f.helo_verified)
3715 {
3716 int rc;
3717 host_item h =
3718 {.name = sender_helo_name, .address = NULL, .mx = MX_NONE, .next = NULL};
3719 dnssec_domains d =
3720 {.request = US"*", .require = US""};
3721
3722 HDEBUG(D_receive) debug_printf("getting IP address for %s\n",
3723 sender_helo_name);
3724 rc = host_find_bydns(&h, NULL, HOST_FIND_BY_A | HOST_FIND_BY_AAAA,
3725 NULL, NULL, NULL, &d, NULL, NULL);
3726 if (rc == HOST_FOUND || rc == HOST_FOUND_LOCAL)
3727 for (host_item * hh = &h; hh; hh = hh->next)
3728 if (Ustrcmp(hh->address, sender_host_address) == 0)
3729 {
3730 f.helo_verified = TRUE;
3731 if (h.dnssec == DS_YES) sender_helo_dnssec = TRUE;
3732 HDEBUG(D_receive)
3733 debug_printf("IP address for %s matches calling address\n"
3734 "Forward DNS security status: %sverified\n",
3735 sender_helo_name, sender_helo_dnssec ? "" : "un");
3736 break;
3737 }
3738 }
3739 }
3740
3741 if (!f.helo_verified) f.helo_verify_failed = TRUE; /* We've tried ... */
3742 return yield;
3743 }
3744
3745
3746
3747
3748 /*************************************************
3749 * Send user response message *
3750 *************************************************/
3751
3752 /* This function is passed a default response code and a user message. It calls
3753 smtp_message_code() to check and possibly modify the response code, and then
3754 calls smtp_respond() to transmit the response. I put this into a function
3755 just to avoid a lot of repetition.
3756
3757 Arguments:
3758 code the response code
3759 user_msg the user message
3760
3761 Returns: nothing
3762 */
3763
3764 static void
smtp_user_msg(uschar * code,uschar * user_msg)3765 smtp_user_msg(uschar *code, uschar *user_msg)
3766 {
3767 int len = 3;
3768 smtp_message_code(&code, &len, &user_msg, NULL, TRUE);
3769 smtp_respond(code, len, TRUE, user_msg);
3770 }
3771
3772
3773
3774 static int
smtp_in_auth(auth_instance * au,uschar ** s,uschar ** ss)3775 smtp_in_auth(auth_instance *au, uschar ** s, uschar ** ss)
3776 {
3777 const uschar *set_id = NULL;
3778 int rc;
3779
3780 /* Run the checking code, passing the remainder of the command line as
3781 data. Initials the $auth<n> variables as empty. Initialize $0 empty and set
3782 it as the only set numerical variable. The authenticator may set $auth<n>
3783 and also set other numeric variables. The $auth<n> variables are preferred
3784 nowadays; the numerical variables remain for backwards compatibility.
3785
3786 Afterwards, have a go at expanding the set_id string, even if
3787 authentication failed - for bad passwords it can be useful to log the
3788 userid. On success, require set_id to expand and exist, and put it in
3789 authenticated_id. Save this in permanent store, as the working store gets
3790 reset at HELO, RSET, etc. */
3791
3792 for (int i = 0; i < AUTH_VARS; i++) auth_vars[i] = NULL;
3793 expand_nmax = 0;
3794 expand_nlength[0] = 0; /* $0 contains nothing */
3795
3796 rc = (au->info->servercode)(au, smtp_cmd_data);
3797 if (au->set_id) set_id = expand_string(au->set_id);
3798 expand_nmax = -1; /* Reset numeric variables */
3799 for (int i = 0; i < AUTH_VARS; i++) auth_vars[i] = NULL; /* Reset $auth<n> */
3800
3801 /* The value of authenticated_id is stored in the spool file and printed in
3802 log lines. It must not contain binary zeros or newline characters. In
3803 normal use, it never will, but when playing around or testing, this error
3804 can (did) happen. To guard against this, ensure that the id contains only
3805 printing characters. */
3806
3807 if (set_id) set_id = string_printing(set_id);
3808
3809 /* For the non-OK cases, set up additional logging data if set_id
3810 is not empty. */
3811
3812 if (rc != OK)
3813 set_id = set_id && *set_id
3814 ? string_sprintf(" (set_id=%s)", set_id) : US"";
3815
3816 /* Switch on the result */
3817
3818 switch(rc)
3819 {
3820 case OK:
3821 if (!au->set_id || set_id) /* Complete success */
3822 {
3823 if (set_id) authenticated_id = string_copy_perm(set_id, TRUE);
3824 sender_host_authenticated = au->name;
3825 sender_host_auth_pubname = au->public_name;
3826 authentication_failed = FALSE;
3827 authenticated_fail_id = NULL; /* Impossible to already be set? */
3828
3829 received_protocol =
3830 (sender_host_address ? protocols : protocols_local)
3831 [pextend + pauthed + (tls_in.active.sock >= 0 ? pcrpted:0)];
3832 *s = *ss = US"235 Authentication succeeded";
3833 authenticated_by = au;
3834 break;
3835 }
3836
3837 /* Authentication succeeded, but we failed to expand the set_id string.
3838 Treat this as a temporary error. */
3839
3840 auth_defer_msg = expand_string_message;
3841 /* Fall through */
3842
3843 case DEFER:
3844 if (set_id) authenticated_fail_id = string_copy_perm(set_id, TRUE);
3845 *s = string_sprintf("435 Unable to authenticate at present%s",
3846 auth_defer_user_msg);
3847 *ss = string_sprintf("435 Unable to authenticate at present%s: %s",
3848 set_id, auth_defer_msg);
3849 break;
3850
3851 case BAD64:
3852 *s = *ss = US"501 Invalid base64 data";
3853 break;
3854
3855 case CANCELLED:
3856 *s = *ss = US"501 Authentication cancelled";
3857 break;
3858
3859 case UNEXPECTED:
3860 *s = *ss = US"553 Initial data not expected";
3861 break;
3862
3863 case FAIL:
3864 if (set_id) authenticated_fail_id = string_copy_perm(set_id, TRUE);
3865 *s = US"535 Incorrect authentication data";
3866 *ss = string_sprintf("535 Incorrect authentication data%s", set_id);
3867 break;
3868
3869 default:
3870 if (set_id) authenticated_fail_id = string_copy_perm(set_id, TRUE);
3871 *s = US"435 Internal error";
3872 *ss = string_sprintf("435 Internal error%s: return %d from authentication "
3873 "check", set_id, rc);
3874 break;
3875 }
3876
3877 return rc;
3878 }
3879
3880
3881
3882
3883
3884 static int
qualify_recipient(uschar ** recipient,uschar * smtp_cmd_data,uschar * tag)3885 qualify_recipient(uschar ** recipient, uschar * smtp_cmd_data, uschar * tag)
3886 {
3887 int rd;
3888 if (f.allow_unqualified_recipient || strcmpic(*recipient, US"postmaster") == 0)
3889 {
3890 DEBUG(D_receive) debug_printf("unqualified address %s accepted\n",
3891 *recipient);
3892 rd = Ustrlen(recipient) + 1;
3893 /* deconst ok as *recipient was not const */
3894 *recipient = US rewrite_address_qualify(*recipient, TRUE);
3895 return rd;
3896 }
3897 smtp_printf("501 %s: recipient address must contain a domain\r\n", FALSE,
3898 smtp_cmd_data);
3899 log_write(L_smtp_syntax_error,
3900 LOG_MAIN|LOG_REJECT, "unqualified %s rejected: <%s> %s%s",
3901 tag, *recipient, host_and_ident(TRUE), host_lookup_msg);
3902 return 0;
3903 }
3904
3905
3906
3907
3908 static void
smtp_quit_handler(uschar ** user_msgp,uschar ** log_msgp)3909 smtp_quit_handler(uschar ** user_msgp, uschar ** log_msgp)
3910 {
3911 HAD(SCH_QUIT);
3912 f.smtp_in_quit = TRUE;
3913 incomplete_transaction_log(US"QUIT");
3914 if ( acl_smtp_quit
3915 && acl_check(ACL_WHERE_QUIT, NULL, acl_smtp_quit, user_msgp, log_msgp)
3916 == ERROR)
3917 log_write(0, LOG_MAIN|LOG_PANIC, "ACL for QUIT returned ERROR: %s",
3918 *log_msgp);
3919
3920 #ifdef EXIM_TCP_CORK
3921 (void) setsockopt(fileno(smtp_out), IPPROTO_TCP, EXIM_TCP_CORK, US &on, sizeof(on));
3922 #endif
3923
3924 if (*user_msgp)
3925 smtp_respond(US"221", 3, TRUE, *user_msgp);
3926 else
3927 smtp_printf("221 %s closing connection\r\n", FALSE, smtp_active_hostname);
3928
3929 #ifdef SERVERSIDE_CLOSE_NOWAIT
3930 # ifndef DISABLE_TLS
3931 tls_close(NULL, TLS_SHUTDOWN_NOWAIT);
3932 # endif
3933
3934 log_write(L_smtp_connection, LOG_MAIN, "%s closed by QUIT",
3935 smtp_get_connection_info());
3936 #else
3937
3938 # ifndef DISABLE_TLS
3939 tls_close(NULL, TLS_SHUTDOWN_WAIT);
3940 # endif
3941
3942 log_write(L_smtp_connection, LOG_MAIN, "%s closed by QUIT",
3943 smtp_get_connection_info());
3944
3945 /* Pause, hoping client will FIN first so that they get the TIME_WAIT.
3946 The socket should become readble (though with no data) */
3947
3948 (void) poll_one_fd(fileno(smtp_in), POLLIN, 200);
3949 #endif /*!SERVERSIDE_CLOSE_NOWAIT*/
3950 }
3951
3952
3953 static void
smtp_rset_handler(void)3954 smtp_rset_handler(void)
3955 {
3956 HAD(SCH_RSET);
3957 incomplete_transaction_log(US"RSET");
3958 smtp_printf("250 Reset OK\r\n", FALSE);
3959 cmd_list[CMD_LIST_RSET].is_mail_cmd = FALSE;
3960 }
3961
3962
3963 static int
expand_mailmax(const uschar * s)3964 expand_mailmax(const uschar * s)
3965 {
3966 if (!(s = expand_cstring(s)))
3967 log_write(0, LOG_MAIN|LOG_PANIC, "failed to expand smtp_accept_max_per_connection");
3968 return *s ? Uatoi(s) : 0;
3969 }
3970
3971 /*************************************************
3972 * Initialize for SMTP incoming message *
3973 *************************************************/
3974
3975 /* This function conducts the initial dialogue at the start of an incoming SMTP
3976 message, and builds a list of recipients. However, if the incoming message
3977 is part of a batch (-bS option) a separate function is called since it would
3978 be messy having tests splattered about all over this function. This function
3979 therefore handles the case where interaction is occurring. The input and output
3980 files are set up in smtp_in and smtp_out.
3981
3982 The global recipients_list is set to point to a vector of recipient_item
3983 blocks, whose number is given by recipients_count. This is extended by the
3984 receive_add_recipient() function. The global variable sender_address is set to
3985 the sender's address. The yield is +1 if a message has been successfully
3986 started, 0 if a QUIT command was encountered or the connection was refused from
3987 the particular host, or -1 if the connection was lost.
3988
3989 Argument: none
3990
3991 Returns: > 0 message successfully started (reached DATA)
3992 = 0 QUIT read or end of file reached or call refused
3993 < 0 lost connection
3994 */
3995
3996 int
smtp_setup_msg(void)3997 smtp_setup_msg(void)
3998 {
3999 int done = 0;
4000 BOOL toomany = FALSE;
4001 BOOL discarded = FALSE;
4002 BOOL last_was_rej_mail = FALSE;
4003 BOOL last_was_rcpt = FALSE;
4004 rmark reset_point = store_mark();
4005
4006 DEBUG(D_receive) debug_printf("smtp_setup_msg entered\n");
4007
4008 /* Reset for start of new message. We allow one RSET not to be counted as a
4009 nonmail command, for those MTAs that insist on sending it between every
4010 message. Ditto for EHLO/HELO and for STARTTLS, to allow for going in and out of
4011 TLS between messages (an Exim client may do this if it has messages queued up
4012 for the host). Note: we do NOT reset AUTH at this point. */
4013
4014 reset_point = smtp_reset(reset_point);
4015 message_ended = END_NOTSTARTED;
4016
4017 chunking_state = f.chunking_offered ? CHUNKING_OFFERED : CHUNKING_NOT_OFFERED;
4018
4019 cmd_list[CMD_LIST_RSET].is_mail_cmd = TRUE;
4020 cmd_list[CMD_LIST_HELO].is_mail_cmd = TRUE;
4021 cmd_list[CMD_LIST_EHLO].is_mail_cmd = TRUE;
4022 #ifndef DISABLE_TLS
4023 cmd_list[CMD_LIST_STARTTLS].is_mail_cmd = TRUE;
4024 #endif
4025
4026 if (lwr_receive_getc != NULL)
4027 {
4028 /* This should have already happened, but if we've gotten confused,
4029 force a reset here. */
4030 DEBUG(D_receive) debug_printf("WARNING: smtp_setup_msg had to restore receive functions to lowers\n");
4031 bdat_pop_receive_functions();
4032 }
4033
4034 /* Set the local signal handler for SIGTERM - it tries to end off tidily */
4035
4036 had_command_sigterm = 0;
4037 os_non_restarting_signal(SIGTERM, command_sigterm_handler);
4038
4039 /* Batched SMTP is handled in a different function. */
4040
4041 if (smtp_batched_input) return smtp_setup_batch_msg();
4042
4043 #ifdef TCP_QUICKACK
4044 if (smtp_in) /* Avoid pure-ACKs while in cmd pingpong phase */
4045 (void) setsockopt(fileno(smtp_in), IPPROTO_TCP, TCP_QUICKACK,
4046 US &off, sizeof(off));
4047 #endif
4048
4049 /* Deal with SMTP commands. This loop is exited by setting done to a POSITIVE
4050 value. The values are 2 larger than the required yield of the function. */
4051
4052 while (done <= 0)
4053 {
4054 const uschar **argv;
4055 uschar *etrn_command;
4056 uschar *etrn_serialize_key;
4057 uschar *errmess;
4058 uschar *log_msg, *smtp_code;
4059 uschar *user_msg = NULL;
4060 uschar *recipient = NULL;
4061 uschar *hello = NULL;
4062 uschar *s, *ss;
4063 BOOL was_rej_mail = FALSE;
4064 BOOL was_rcpt = FALSE;
4065 void (*oldsignal)(int);
4066 pid_t pid;
4067 int start, end, sender_domain, recipient_domain;
4068 int rc;
4069 int c;
4070 uschar *orcpt = NULL;
4071 int dsn_flags;
4072 gstring * g;
4073
4074 #ifdef AUTH_TLS
4075 /* Check once per STARTTLS or SSL-on-connect for a TLS AUTH */
4076 if ( tls_in.active.sock >= 0
4077 && tls_in.peercert
4078 && tls_in.certificate_verified
4079 && cmd_list[CMD_LIST_TLS_AUTH].is_mail_cmd
4080 )
4081 {
4082 cmd_list[CMD_LIST_TLS_AUTH].is_mail_cmd = FALSE;
4083
4084 for (auth_instance * au = auths; au; au = au->next)
4085 if (strcmpic(US"tls", au->driver_name) == 0)
4086 {
4087 if ( acl_smtp_auth
4088 && (rc = acl_check(ACL_WHERE_AUTH, NULL, acl_smtp_auth,
4089 &user_msg, &log_msg)) != OK
4090 )
4091 done = smtp_handle_acl_fail(ACL_WHERE_AUTH, rc, user_msg, log_msg);
4092 else
4093 {
4094 smtp_cmd_data = NULL;
4095
4096 if (smtp_in_auth(au, &s, &ss) == OK)
4097 { DEBUG(D_auth) debug_printf("tls auth succeeded\n"); }
4098 else
4099 { DEBUG(D_auth) debug_printf("tls auth not succeeded\n"); }
4100 }
4101 break;
4102 }
4103 }
4104 #endif
4105
4106 switch(smtp_read_command(
4107 #ifndef DISABLE_PIPE_CONNECT
4108 !fl.pipe_connect_acceptable,
4109 #else
4110 TRUE,
4111 #endif
4112 GETC_BUFFER_UNLIMITED))
4113 {
4114 /* The AUTH command is not permitted to occur inside a transaction, and may
4115 occur successfully only once per connection. Actually, that isn't quite
4116 true. When TLS is started, all previous information about a connection must
4117 be discarded, so a new AUTH is permitted at that time.
4118
4119 AUTH may only be used when it has been advertised. However, it seems that
4120 there are clients that send AUTH when it hasn't been advertised, some of
4121 them even doing this after HELO. And there are MTAs that accept this. Sigh.
4122 So there's a get-out that allows this to happen.
4123
4124 AUTH is initially labelled as a "nonmail command" so that one occurrence
4125 doesn't get counted. We change the label here so that multiple failing
4126 AUTHS will eventually hit the nonmail threshold. */
4127
4128 case AUTH_CMD:
4129 HAD(SCH_AUTH);
4130 authentication_failed = TRUE;
4131 cmd_list[CMD_LIST_AUTH].is_mail_cmd = FALSE;
4132
4133 if (!fl.auth_advertised && !f.allow_auth_unadvertised)
4134 {
4135 done = synprot_error(L_smtp_protocol_error, 503, NULL,
4136 US"AUTH command used when not advertised");
4137 break;
4138 }
4139 if (sender_host_authenticated)
4140 {
4141 done = synprot_error(L_smtp_protocol_error, 503, NULL,
4142 US"already authenticated");
4143 break;
4144 }
4145 if (sender_address)
4146 {
4147 done = synprot_error(L_smtp_protocol_error, 503, NULL,
4148 US"not permitted in mail transaction");
4149 break;
4150 }
4151
4152 /* Check the ACL */
4153
4154 if ( acl_smtp_auth
4155 && (rc = acl_check(ACL_WHERE_AUTH, NULL, acl_smtp_auth,
4156 &user_msg, &log_msg)) != OK
4157 )
4158 {
4159 done = smtp_handle_acl_fail(ACL_WHERE_AUTH, rc, user_msg, log_msg);
4160 break;
4161 }
4162
4163 /* Find the name of the requested authentication mechanism. */
4164
4165 s = smtp_cmd_data;
4166 for (; (c = *smtp_cmd_data) && !isspace(c); smtp_cmd_data++)
4167 if (!isalnum(c) && c != '-' && c != '_')
4168 {
4169 done = synprot_error(L_smtp_syntax_error, 501, NULL,
4170 US"invalid character in authentication mechanism name");
4171 goto COMMAND_LOOP;
4172 }
4173
4174 /* If not at the end of the line, we must be at white space. Terminate the
4175 name and move the pointer on to any data that may be present. */
4176
4177 if (*smtp_cmd_data)
4178 {
4179 *smtp_cmd_data++ = 0;
4180 while (isspace(*smtp_cmd_data)) smtp_cmd_data++;
4181 }
4182
4183 /* Search for an authentication mechanism which is configured for use
4184 as a server and which has been advertised (unless, sigh, allow_auth_
4185 unadvertised is set). */
4186
4187 {
4188 auth_instance * au;
4189 for (au = auths; au; au = au->next)
4190 if (strcmpic(s, au->public_name) == 0 && au->server &&
4191 (au->advertised || f.allow_auth_unadvertised))
4192 break;
4193
4194 if (au)
4195 {
4196 c = smtp_in_auth(au, &s, &ss);
4197
4198 smtp_printf("%s\r\n", FALSE, s);
4199 if (c != OK)
4200 log_write(0, LOG_MAIN|LOG_REJECT, "%s authenticator failed for %s: %s",
4201 au->name, host_and_ident(FALSE), ss);
4202 }
4203 else
4204 done = synprot_error(L_smtp_protocol_error, 504, NULL,
4205 string_sprintf("%s authentication mechanism not supported", s));
4206 }
4207
4208 break; /* AUTH_CMD */
4209
4210 /* The HELO/EHLO commands are permitted to appear in the middle of a
4211 session as well as at the beginning. They have the effect of a reset in
4212 addition to their other functions. Their absence at the start cannot be
4213 taken to be an error.
4214
4215 RFC 2821 says:
4216
4217 If the EHLO command is not acceptable to the SMTP server, 501, 500,
4218 or 502 failure replies MUST be returned as appropriate. The SMTP
4219 server MUST stay in the same state after transmitting these replies
4220 that it was in before the EHLO was received.
4221
4222 Therefore, we do not do the reset until after checking the command for
4223 acceptability. This change was made for Exim release 4.11. Previously
4224 it did the reset first. */
4225
4226 case HELO_CMD:
4227 HAD(SCH_HELO);
4228 hello = US"HELO";
4229 fl.esmtp = FALSE;
4230 goto HELO_EHLO;
4231
4232 case EHLO_CMD:
4233 HAD(SCH_EHLO);
4234 hello = US"EHLO";
4235 fl.esmtp = TRUE;
4236
4237 HELO_EHLO: /* Common code for HELO and EHLO */
4238 cmd_list[CMD_LIST_HELO].is_mail_cmd = FALSE;
4239 cmd_list[CMD_LIST_EHLO].is_mail_cmd = FALSE;
4240
4241 /* Reject the HELO if its argument was invalid or non-existent. A
4242 successful check causes the argument to be saved in malloc store. */
4243
4244 if (!check_helo(smtp_cmd_data))
4245 {
4246 smtp_printf("501 Syntactically invalid %s argument(s)\r\n", FALSE, hello);
4247
4248 log_write(0, LOG_MAIN|LOG_REJECT, "rejected %s from %s: syntactically "
4249 "invalid argument(s): %s", hello, host_and_ident(FALSE),
4250 *smtp_cmd_argument == 0 ? US"(no argument given)" :
4251 string_printing(smtp_cmd_argument));
4252
4253 if (++synprot_error_count > smtp_max_synprot_errors)
4254 {
4255 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
4256 "syntax or protocol errors (last command was \"%s\", %s)",
4257 host_and_ident(FALSE), string_printing(smtp_cmd_buffer),
4258 string_from_gstring(s_connhad_log(NULL))
4259 );
4260 done = 1;
4261 }
4262
4263 break;
4264 }
4265
4266 /* If sender_host_unknown is true, we have got here via the -bs interface,
4267 not called from inetd. Otherwise, we are running an IP connection and the
4268 host address will be set. If the helo name is the primary name of this
4269 host and we haven't done a reverse lookup, force one now. If helo_verify_required
4270 is set, ensure that the HELO name matches the actual host. If helo_verify
4271 is set, do the same check, but softly. */
4272
4273 if (!f.sender_host_unknown)
4274 {
4275 BOOL old_helo_verified = f.helo_verified;
4276 uschar *p = smtp_cmd_data;
4277
4278 while (*p != 0 && !isspace(*p)) { *p = tolower(*p); p++; }
4279 *p = 0;
4280
4281 /* Force a reverse lookup if HELO quoted something in helo_lookup_domains
4282 because otherwise the log can be confusing. */
4283
4284 if ( !sender_host_name
4285 && match_isinlist(sender_helo_name, CUSS &helo_lookup_domains, 0,
4286 &domainlist_anchor, NULL, MCL_DOMAIN, TRUE, NULL) == OK)
4287 (void)host_name_lookup();
4288
4289 /* Rebuild the fullhost info to include the HELO name (and the real name
4290 if it was looked up.) */
4291
4292 host_build_sender_fullhost(); /* Rebuild */
4293 set_process_info("handling%s incoming connection from %s",
4294 tls_in.active.sock >= 0 ? " TLS" : "", host_and_ident(FALSE));
4295
4296 /* Verify if configured. This doesn't give much security, but it does
4297 make some people happy to be able to do it. If helo_verify_required is set,
4298 (host matches helo_verify_hosts) failure forces rejection. If helo_verify
4299 is set (host matches helo_try_verify_hosts), it does not. This is perhaps
4300 now obsolescent, since the verification can now be requested selectively
4301 at ACL time. */
4302
4303 f.helo_verified = f.helo_verify_failed = sender_helo_dnssec = FALSE;
4304 if (fl.helo_verify_required || fl.helo_verify)
4305 {
4306 BOOL tempfail = !smtp_verify_helo();
4307 if (!f.helo_verified)
4308 {
4309 if (fl.helo_verify_required)
4310 {
4311 smtp_printf("%d %s argument does not match calling host\r\n", FALSE,
4312 tempfail? 451 : 550, hello);
4313 log_write(0, LOG_MAIN|LOG_REJECT, "%srejected \"%s %s\" from %s",
4314 tempfail? "temporarily " : "",
4315 hello, sender_helo_name, host_and_ident(FALSE));
4316 f.helo_verified = old_helo_verified;
4317 break; /* End of HELO/EHLO processing */
4318 }
4319 HDEBUG(D_all) debug_printf("%s verification failed but host is in "
4320 "helo_try_verify_hosts\n", hello);
4321 }
4322 }
4323 }
4324
4325 #ifdef SUPPORT_SPF
4326 /* set up SPF context */
4327 spf_conn_init(sender_helo_name, sender_host_address);
4328 #endif
4329
4330 /* Apply an ACL check if one is defined; afterwards, recheck
4331 synchronization in case the client started sending in a delay. */
4332
4333 if (acl_smtp_helo)
4334 if ((rc = acl_check(ACL_WHERE_HELO, NULL, acl_smtp_helo,
4335 &user_msg, &log_msg)) != OK)
4336 {
4337 done = smtp_handle_acl_fail(ACL_WHERE_HELO, rc, user_msg, log_msg);
4338 sender_helo_name = NULL;
4339 host_build_sender_fullhost(); /* Rebuild */
4340 break;
4341 }
4342 #ifndef DISABLE_PIPE_CONNECT
4343 else if (!fl.pipe_connect_acceptable && !check_sync())
4344 #else
4345 else if (!check_sync())
4346 #endif
4347 goto SYNC_FAILURE;
4348
4349 /* Generate an OK reply. The default string includes the ident if present,
4350 and also the IP address if present. Reflecting back the ident is intended
4351 as a deterrent to mail forgers. For maximum efficiency, and also because
4352 some broken systems expect each response to be in a single packet, arrange
4353 that the entire reply is sent in one write(). */
4354
4355 fl.auth_advertised = FALSE;
4356 f.smtp_in_pipelining_advertised = FALSE;
4357 #ifndef DISABLE_TLS
4358 fl.tls_advertised = FALSE;
4359 #endif
4360 fl.dsn_advertised = FALSE;
4361 #ifdef SUPPORT_I18N
4362 fl.smtputf8_advertised = FALSE;
4363 #endif
4364
4365 /* Expand the per-connection message count limit option */
4366 smtp_mailcmd_max = expand_mailmax(smtp_accept_max_per_connection);
4367
4368 smtp_code = US"250 "; /* Default response code plus space*/
4369 if (!user_msg)
4370 {
4371 /* sender_host_name below will be tainted, so save on copy when we hit it */
4372 g = string_get_tainted(24, TRUE);
4373 g = string_fmt_append(g, "%.3s %s Hello %s%s%s",
4374 smtp_code,
4375 smtp_active_hostname,
4376 sender_ident ? sender_ident : US"",
4377 sender_ident ? US" at " : US"",
4378 sender_host_name ? sender_host_name : sender_helo_name);
4379
4380 if (sender_host_address)
4381 g = string_fmt_append(g, " [%s]", sender_host_address);
4382 }
4383
4384 /* A user-supplied EHLO greeting may not contain more than one line. Note
4385 that the code returned by smtp_message_code() includes the terminating
4386 whitespace character. */
4387
4388 else
4389 {
4390 char *ss;
4391 int codelen = 4;
4392 smtp_message_code(&smtp_code, &codelen, &user_msg, NULL, TRUE);
4393 s = string_sprintf("%.*s%s", codelen, smtp_code, user_msg);
4394 if ((ss = strpbrk(CS s, "\r\n")) != NULL)
4395 {
4396 log_write(0, LOG_MAIN|LOG_PANIC, "EHLO/HELO response must not contain "
4397 "newlines: message truncated: %s", string_printing(s));
4398 *ss = 0;
4399 }
4400 g = string_cat(NULL, s);
4401 }
4402
4403 g = string_catn(g, US"\r\n", 2);
4404
4405 /* If we received EHLO, we must create a multiline response which includes
4406 the functions supported. */
4407
4408 if (fl.esmtp)
4409 {
4410 g->s[3] = '-';
4411
4412 /* I'm not entirely happy with this, as an MTA is supposed to check
4413 that it has enough room to accept a message of maximum size before
4414 it sends this. However, there seems little point in not sending it.
4415 The actual size check happens later at MAIL FROM time. By postponing it
4416 till then, VRFY and EXPN can be used after EHLO when space is short. */
4417
4418 if (thismessage_size_limit > 0)
4419 g = string_fmt_append(g, "%.3s-SIZE %d\r\n", smtp_code,
4420 thismessage_size_limit);
4421 else
4422 {
4423 g = string_catn(g, smtp_code, 3);
4424 g = string_catn(g, US"-SIZE\r\n", 7);
4425 }
4426
4427 #ifdef EXPERIMENTAL_ESMTP_LIMITS
4428 if ( (smtp_mailcmd_max > 0 || recipients_max)
4429 && verify_check_host(&limits_advertise_hosts) == OK)
4430 {
4431 g = string_fmt_append(g, "%.3s-LIMITS", smtp_code);
4432 if (smtp_mailcmd_max > 0)
4433 g = string_fmt_append(g, " MAILMAX=%d", smtp_mailcmd_max);
4434 if (recipients_max)
4435 g = string_fmt_append(g, " RCPTMAX=%d", recipients_max);
4436 g = string_catn(g, US"\r\n", 2);
4437 }
4438 #endif
4439
4440 /* Exim does not do protocol conversion or data conversion. It is 8-bit
4441 clean; if it has an 8-bit character in its hand, it just sends it. It
4442 cannot therefore specify 8BITMIME and remain consistent with the RFCs.
4443 However, some users want this option simply in order to stop MUAs
4444 mangling messages that contain top-bit-set characters. It is therefore
4445 provided as an option. */
4446
4447 if (accept_8bitmime)
4448 {
4449 g = string_catn(g, smtp_code, 3);
4450 g = string_catn(g, US"-8BITMIME\r\n", 11);
4451 }
4452
4453 /* Advertise DSN support if configured to do so. */
4454 if (verify_check_host(&dsn_advertise_hosts) != FAIL)
4455 {
4456 g = string_catn(g, smtp_code, 3);
4457 g = string_catn(g, US"-DSN\r\n", 6);
4458 fl.dsn_advertised = TRUE;
4459 }
4460
4461 /* Advertise ETRN/VRFY/EXPN if there's are ACL checking whether a host is
4462 permitted to issue them; a check is made when any host actually tries. */
4463
4464 if (acl_smtp_etrn)
4465 {
4466 g = string_catn(g, smtp_code, 3);
4467 g = string_catn(g, US"-ETRN\r\n", 7);
4468 }
4469 if (acl_smtp_vrfy)
4470 {
4471 g = string_catn(g, smtp_code, 3);
4472 g = string_catn(g, US"-VRFY\r\n", 7);
4473 }
4474 if (acl_smtp_expn)
4475 {
4476 g = string_catn(g, smtp_code, 3);
4477 g = string_catn(g, US"-EXPN\r\n", 7);
4478 }
4479
4480 /* Exim is quite happy with pipelining, so let the other end know that
4481 it is safe to use it, unless advertising is disabled. */
4482
4483 if ( f.pipelining_enable
4484 && verify_check_host(&pipelining_advertise_hosts) == OK)
4485 {
4486 g = string_catn(g, smtp_code, 3);
4487 g = string_catn(g, US"-PIPELINING\r\n", 13);
4488 sync_cmd_limit = NON_SYNC_CMD_PIPELINING;
4489 f.smtp_in_pipelining_advertised = TRUE;
4490
4491 #ifndef DISABLE_PIPE_CONNECT
4492 if (fl.pipe_connect_acceptable)
4493 {
4494 f.smtp_in_early_pipe_advertised = TRUE;
4495 g = string_catn(g, smtp_code, 3);
4496 g = string_catn(g, US"-" EARLY_PIPE_FEATURE_NAME "\r\n", EARLY_PIPE_FEATURE_LEN+3);
4497 }
4498 #endif
4499 }
4500
4501
4502 /* If any server authentication mechanisms are configured, advertise
4503 them if the current host is in auth_advertise_hosts. The problem with
4504 advertising always is that some clients then require users to
4505 authenticate (and aren't configurable otherwise) even though it may not
4506 be necessary (e.g. if the host is in host_accept_relay).
4507
4508 RFC 2222 states that SASL mechanism names contain only upper case
4509 letters, so output the names in upper case, though we actually recognize
4510 them in either case in the AUTH command. */
4511
4512 if ( auths
4513 #ifdef AUTH_TLS
4514 && !sender_host_authenticated
4515 #endif
4516 && verify_check_host(&auth_advertise_hosts) == OK
4517 )
4518 {
4519 BOOL first = TRUE;
4520 for (auth_instance * au = auths; au; au = au->next)
4521 {
4522 au->advertised = FALSE;
4523 if (au->server)
4524 {
4525 DEBUG(D_auth+D_expand) debug_printf_indent(
4526 "Evaluating advertise_condition for %s %s athenticator\n",
4527 au->name, au->public_name);
4528 if ( !au->advertise_condition
4529 || expand_check_condition(au->advertise_condition, au->name,
4530 US"authenticator")
4531 )
4532 {
4533 int saveptr;
4534 if (first)
4535 {
4536 g = string_catn(g, smtp_code, 3);
4537 g = string_catn(g, US"-AUTH", 5);
4538 first = FALSE;
4539 fl.auth_advertised = TRUE;
4540 }
4541 saveptr = g->ptr;
4542 g = string_catn(g, US" ", 1);
4543 g = string_cat (g, au->public_name);
4544 while (++saveptr < g->ptr) g->s[saveptr] = toupper(g->s[saveptr]);
4545 au->advertised = TRUE;
4546 }
4547 }
4548 }
4549
4550 if (!first) g = string_catn(g, US"\r\n", 2);
4551 }
4552
4553 /* RFC 3030 CHUNKING */
4554
4555 if (verify_check_host(&chunking_advertise_hosts) != FAIL)
4556 {
4557 g = string_catn(g, smtp_code, 3);
4558 g = string_catn(g, US"-CHUNKING\r\n", 11);
4559 f.chunking_offered = TRUE;
4560 chunking_state = CHUNKING_OFFERED;
4561 }
4562
4563 /* Advertise TLS (Transport Level Security) aka SSL (Secure Socket Layer)
4564 if it has been included in the binary, and the host matches
4565 tls_advertise_hosts. We must *not* advertise if we are already in a
4566 secure connection. */
4567
4568 #ifndef DISABLE_TLS
4569 if (tls_in.active.sock < 0 &&
4570 verify_check_host(&tls_advertise_hosts) != FAIL)
4571 {
4572 g = string_catn(g, smtp_code, 3);
4573 g = string_catn(g, US"-STARTTLS\r\n", 11);
4574 fl.tls_advertised = TRUE;
4575 }
4576 #endif
4577
4578 #ifndef DISABLE_PRDR
4579 /* Per Recipient Data Response, draft by Eric A. Hall extending RFC */
4580 if (prdr_enable)
4581 {
4582 g = string_catn(g, smtp_code, 3);
4583 g = string_catn(g, US"-PRDR\r\n", 7);
4584 }
4585 #endif
4586
4587 #ifdef SUPPORT_I18N
4588 if ( accept_8bitmime
4589 && verify_check_host(&smtputf8_advertise_hosts) != FAIL)
4590 {
4591 g = string_catn(g, smtp_code, 3);
4592 g = string_catn(g, US"-SMTPUTF8\r\n", 11);
4593 fl.smtputf8_advertised = TRUE;
4594 }
4595 #endif
4596
4597 /* Finish off the multiline reply with one that is always available. */
4598
4599 g = string_catn(g, smtp_code, 3);
4600 g = string_catn(g, US" HELP\r\n", 7);
4601 }
4602
4603 /* Terminate the string (for debug), write it, and note that HELO/EHLO
4604 has been seen. */
4605
4606 #ifndef DISABLE_TLS
4607 if (tls_in.active.sock >= 0)
4608 (void)tls_write(NULL, g->s, g->ptr,
4609 # ifndef DISABLE_PIPE_CONNECT
4610 fl.pipe_connect_acceptable && pipeline_connect_sends());
4611 # else
4612 FALSE);
4613 # endif
4614 else
4615 #endif
4616 (void) fwrite(g->s, 1, g->ptr, smtp_out);
4617
4618 DEBUG(D_receive)
4619 {
4620 uschar *cr;
4621
4622 (void) string_from_gstring(g);
4623 while ((cr = Ustrchr(g->s, '\r')) != NULL) /* lose CRs */
4624 memmove(cr, cr + 1, (g->ptr--) - (cr - g->s));
4625 debug_printf("SMTP>> %s", g->s);
4626 }
4627 fl.helo_seen = TRUE;
4628
4629 /* Reset the protocol and the state, abandoning any previous message. */
4630 received_protocol =
4631 (sender_host_address ? protocols : protocols_local)
4632 [ (fl.esmtp
4633 ? pextend + (sender_host_authenticated ? pauthed : 0)
4634 : pnormal)
4635 + (tls_in.active.sock >= 0 ? pcrpted : 0)
4636 ];
4637 cancel_cutthrough_connection(TRUE, US"sent EHLO response");
4638 reset_point = smtp_reset(reset_point);
4639 toomany = FALSE;
4640 break; /* HELO/EHLO */
4641
4642
4643 /* The MAIL command requires an address as an operand. All we do
4644 here is to parse it for syntactic correctness. The form "<>" is
4645 a special case which converts into an empty string. The start/end
4646 pointers in the original are not used further for this address, as
4647 it is the canonical extracted address which is all that is kept. */
4648
4649 case MAIL_CMD:
4650 HAD(SCH_MAIL);
4651 smtp_mailcmd_count++; /* Count for limit and ratelimit */
4652 message_start();
4653 was_rej_mail = TRUE; /* Reset if accepted */
4654 env_mail_type_t * mail_args; /* Sanity check & validate args */
4655
4656 if (!fl.helo_seen)
4657 if ( fl.helo_verify_required
4658 || verify_check_host(&hosts_require_helo) == OK)
4659 {
4660 smtp_printf("503 HELO or EHLO required\r\n", FALSE);
4661 log_write(0, LOG_MAIN|LOG_REJECT, "rejected MAIL from %s: no "
4662 "HELO/EHLO given", host_and_ident(FALSE));
4663 break;
4664 }
4665 else if (smtp_mailcmd_max < 0)
4666 smtp_mailcmd_max = expand_mailmax(smtp_accept_max_per_connection);
4667
4668 if (sender_address)
4669 {
4670 done = synprot_error(L_smtp_protocol_error, 503, NULL,
4671 US"sender already given");
4672 break;
4673 }
4674
4675 if (!*smtp_cmd_data)
4676 {
4677 done = synprot_error(L_smtp_protocol_error, 501, NULL,
4678 US"MAIL must have an address operand");
4679 break;
4680 }
4681
4682 /* Check to see if the limit for messages per connection would be
4683 exceeded by accepting further messages. */
4684
4685 if (smtp_mailcmd_max > 0 && smtp_mailcmd_count > smtp_mailcmd_max)
4686 {
4687 smtp_printf("421 too many messages in this connection\r\n", FALSE);
4688 log_write(0, LOG_MAIN|LOG_REJECT, "rejected MAIL command %s: too many "
4689 "messages in one connection", host_and_ident(TRUE));
4690 break;
4691 }
4692
4693 /* Reset for start of message - even if this is going to fail, we
4694 obviously need to throw away any previous data. */
4695
4696 cancel_cutthrough_connection(TRUE, US"MAIL received");
4697 reset_point = smtp_reset(reset_point);
4698 toomany = FALSE;
4699 sender_data = recipient_data = NULL;
4700
4701 /* Loop, checking for ESMTP additions to the MAIL FROM command. */
4702
4703 if (fl.esmtp) for(;;)
4704 {
4705 uschar *name, *value, *end;
4706 unsigned long int size;
4707 BOOL arg_error = FALSE;
4708
4709 if (!extract_option(&name, &value)) break;
4710
4711 for (mail_args = env_mail_type_list;
4712 mail_args->value != ENV_MAIL_OPT_NULL;
4713 mail_args++
4714 )
4715 if (strcmpic(name, mail_args->name) == 0)
4716 break;
4717 if (mail_args->need_value && strcmpic(value, US"") == 0)
4718 break;
4719
4720 switch(mail_args->value)
4721 {
4722 /* Handle SIZE= by reading the value. We don't do the check till later,
4723 in order to be able to log the sender address on failure. */
4724 case ENV_MAIL_OPT_SIZE:
4725 if (((size = Ustrtoul(value, &end, 10)), *end == 0))
4726 {
4727 if ((size == ULONG_MAX && errno == ERANGE) || size > INT_MAX)
4728 size = INT_MAX;
4729 message_size = (int)size;
4730 }
4731 else
4732 arg_error = TRUE;
4733 break;
4734
4735 /* If this session was initiated with EHLO and accept_8bitmime is set,
4736 Exim will have indicated that it supports the BODY=8BITMIME option. In
4737 fact, it does not support this according to the RFCs, in that it does not
4738 take any special action for forwarding messages containing 8-bit
4739 characters. That is why accept_8bitmime is not the default setting, but
4740 some sites want the action that is provided. We recognize both "8BITMIME"
4741 and "7BIT" as body types, but take no action. */
4742 case ENV_MAIL_OPT_BODY:
4743 if (accept_8bitmime) {
4744 if (strcmpic(value, US"8BITMIME") == 0)
4745 body_8bitmime = 8;
4746 else if (strcmpic(value, US"7BIT") == 0)
4747 body_8bitmime = 7;
4748 else
4749 {
4750 body_8bitmime = 0;
4751 done = synprot_error(L_smtp_syntax_error, 501, NULL,
4752 US"invalid data for BODY");
4753 goto COMMAND_LOOP;
4754 }
4755 DEBUG(D_receive) debug_printf("8BITMIME: %d\n", body_8bitmime);
4756 break;
4757 }
4758 arg_error = TRUE;
4759 break;
4760
4761 /* Handle the two DSN options, but only if configured to do so (which
4762 will have caused "DSN" to be given in the EHLO response). The code itself
4763 is included only if configured in at build time. */
4764
4765 case ENV_MAIL_OPT_RET:
4766 if (fl.dsn_advertised)
4767 {
4768 /* Check if RET has already been set */
4769 if (dsn_ret > 0)
4770 {
4771 done = synprot_error(L_smtp_syntax_error, 501, NULL,
4772 US"RET can be specified once only");
4773 goto COMMAND_LOOP;
4774 }
4775 dsn_ret = strcmpic(value, US"HDRS") == 0
4776 ? dsn_ret_hdrs
4777 : strcmpic(value, US"FULL") == 0
4778 ? dsn_ret_full
4779 : 0;
4780 DEBUG(D_receive) debug_printf("DSN_RET: %d\n", dsn_ret);
4781 /* Check for invalid invalid value, and exit with error */
4782 if (dsn_ret == 0)
4783 {
4784 done = synprot_error(L_smtp_syntax_error, 501, NULL,
4785 US"Value for RET is invalid");
4786 goto COMMAND_LOOP;
4787 }
4788 }
4789 break;
4790 case ENV_MAIL_OPT_ENVID:
4791 if (fl.dsn_advertised)
4792 {
4793 /* Check if the dsn envid has been already set */
4794 if (dsn_envid)
4795 {
4796 done = synprot_error(L_smtp_syntax_error, 501, NULL,
4797 US"ENVID can be specified once only");
4798 goto COMMAND_LOOP;
4799 }
4800 dsn_envid = string_copy(value);
4801 DEBUG(D_receive) debug_printf("DSN_ENVID: %s\n", dsn_envid);
4802 }
4803 break;
4804
4805 /* Handle the AUTH extension. If the value given is not "<>" and either
4806 the ACL says "yes" or there is no ACL but the sending host is
4807 authenticated, we set it up as the authenticated sender. However, if the
4808 authenticator set a condition to be tested, we ignore AUTH on MAIL unless
4809 the condition is met. The value of AUTH is an xtext, which means that +,
4810 = and cntrl chars are coded in hex; however "<>" is unaffected by this
4811 coding. */
4812 case ENV_MAIL_OPT_AUTH:
4813 if (Ustrcmp(value, "<>") != 0)
4814 {
4815 int rc;
4816 uschar *ignore_msg;
4817
4818 if (auth_xtextdecode(value, &authenticated_sender) < 0)
4819 {
4820 /* Put back terminator overrides for error message */
4821 value[-1] = '=';
4822 name[-1] = ' ';
4823 done = synprot_error(L_smtp_syntax_error, 501, NULL,
4824 US"invalid data for AUTH");
4825 goto COMMAND_LOOP;
4826 }
4827 if (!acl_smtp_mailauth)
4828 {
4829 ignore_msg = US"client not authenticated";
4830 rc = sender_host_authenticated ? OK : FAIL;
4831 }
4832 else
4833 {
4834 ignore_msg = US"rejected by ACL";
4835 rc = acl_check(ACL_WHERE_MAILAUTH, NULL, acl_smtp_mailauth,
4836 &user_msg, &log_msg);
4837 }
4838
4839 switch (rc)
4840 {
4841 case OK:
4842 if (authenticated_by == NULL ||
4843 authenticated_by->mail_auth_condition == NULL ||
4844 expand_check_condition(authenticated_by->mail_auth_condition,
4845 authenticated_by->name, US"authenticator"))
4846 break; /* Accept the AUTH */
4847
4848 ignore_msg = US"server_mail_auth_condition failed";
4849 if (authenticated_id != NULL)
4850 ignore_msg = string_sprintf("%s: authenticated ID=\"%s\"",
4851 ignore_msg, authenticated_id);
4852
4853 /* Fall through */
4854
4855 case FAIL:
4856 authenticated_sender = NULL;
4857 log_write(0, LOG_MAIN, "ignoring AUTH=%s from %s (%s)",
4858 value, host_and_ident(TRUE), ignore_msg);
4859 break;
4860
4861 /* Should only get DEFER or ERROR here. Put back terminator
4862 overrides for error message */
4863
4864 default:
4865 value[-1] = '=';
4866 name[-1] = ' ';
4867 (void)smtp_handle_acl_fail(ACL_WHERE_MAILAUTH, rc, user_msg,
4868 log_msg);
4869 goto COMMAND_LOOP;
4870 }
4871 }
4872 break;
4873
4874 #ifndef DISABLE_PRDR
4875 case ENV_MAIL_OPT_PRDR:
4876 if (prdr_enable)
4877 prdr_requested = TRUE;
4878 break;
4879 #endif
4880
4881 #ifdef SUPPORT_I18N
4882 case ENV_MAIL_OPT_UTF8:
4883 if (!fl.smtputf8_advertised)
4884 {
4885 done = synprot_error(L_smtp_syntax_error, 501, NULL,
4886 US"SMTPUTF8 used when not advertised");
4887 goto COMMAND_LOOP;
4888 }
4889
4890 DEBUG(D_receive) debug_printf("smtputf8 requested\n");
4891 message_smtputf8 = allow_utf8_domains = TRUE;
4892 if (Ustrncmp(received_protocol, US"utf8", 4) != 0)
4893 {
4894 int old_pool = store_pool;
4895 store_pool = POOL_PERM;
4896 received_protocol = string_sprintf("utf8%s", received_protocol);
4897 store_pool = old_pool;
4898 }
4899 break;
4900 #endif
4901
4902 /* No valid option. Stick back the terminator characters and break
4903 the loop. Do the name-terminator second as extract_option sets
4904 value==name when it found no equal-sign.
4905 An error for a malformed address will occur. */
4906 case ENV_MAIL_OPT_NULL:
4907 value[-1] = '=';
4908 name[-1] = ' ';
4909 arg_error = TRUE;
4910 break;
4911
4912 default: assert(0);
4913 }
4914 /* Break out of for loop if switch() had bad argument or
4915 when start of the email address is reached */
4916 if (arg_error) break;
4917 }
4918
4919 /* If we have passed the threshold for rate limiting, apply the current
4920 delay, and update it for next time, provided this is a limited host. */
4921
4922 if (smtp_mailcmd_count > smtp_rlm_threshold &&
4923 verify_check_host(&smtp_ratelimit_hosts) == OK)
4924 {
4925 DEBUG(D_receive) debug_printf("rate limit MAIL: delay %.3g sec\n",
4926 smtp_delay_mail/1000.0);
4927 millisleep((int)smtp_delay_mail);
4928 smtp_delay_mail *= smtp_rlm_factor;
4929 if (smtp_delay_mail > (double)smtp_rlm_limit)
4930 smtp_delay_mail = (double)smtp_rlm_limit;
4931 }
4932
4933 /* Now extract the address, first applying any SMTP-time rewriting. The
4934 TRUE flag allows "<>" as a sender address. */
4935
4936 raw_sender = rewrite_existflags & rewrite_smtp
4937 /* deconst ok as smtp_cmd_data was not const */
4938 ? US rewrite_one(smtp_cmd_data, rewrite_smtp, NULL, FALSE, US"",
4939 global_rewrite_rules)
4940 : smtp_cmd_data;
4941
4942 raw_sender =
4943 parse_extract_address(raw_sender, &errmess, &start, &end, &sender_domain,
4944 TRUE);
4945
4946 if (!raw_sender)
4947 {
4948 done = synprot_error(L_smtp_syntax_error, 501, smtp_cmd_data, errmess);
4949 break;
4950 }
4951
4952 sender_address = raw_sender;
4953
4954 /* If there is a configured size limit for mail, check that this message
4955 doesn't exceed it. The check is postponed to this point so that the sender
4956 can be logged. */
4957
4958 if (thismessage_size_limit > 0 && message_size > thismessage_size_limit)
4959 {
4960 smtp_printf("552 Message size exceeds maximum permitted\r\n", FALSE);
4961 log_write(L_size_reject,
4962 LOG_MAIN|LOG_REJECT, "rejected MAIL FROM:<%s> %s: "
4963 "message too big: size%s=%d max=%d",
4964 sender_address,
4965 host_and_ident(TRUE),
4966 (message_size == INT_MAX)? ">" : "",
4967 message_size,
4968 thismessage_size_limit);
4969 sender_address = NULL;
4970 break;
4971 }
4972
4973 /* Check there is enough space on the disk unless configured not to.
4974 When smtp_check_spool_space is set, the check is for thismessage_size_limit
4975 plus the current message - i.e. we accept the message only if it won't
4976 reduce the space below the threshold. Add 5000 to the size to allow for
4977 overheads such as the Received: line and storing of recipients, etc.
4978 By putting the check here, even when SIZE is not given, it allow VRFY
4979 and EXPN etc. to be used when space is short. */
4980
4981 if (!receive_check_fs(
4982 smtp_check_spool_space && message_size >= 0
4983 ? message_size + 5000 : 0))
4984 {
4985 smtp_printf("452 Space shortage, please try later\r\n", FALSE);
4986 sender_address = NULL;
4987 break;
4988 }
4989
4990 /* If sender_address is unqualified, reject it, unless this is a locally
4991 generated message, or the sending host or net is permitted to send
4992 unqualified addresses - typically local machines behaving as MUAs -
4993 in which case just qualify the address. The flag is set above at the start
4994 of the SMTP connection. */
4995
4996 if (!sender_domain && *sender_address)
4997 if (f.allow_unqualified_sender)
4998 {
4999 sender_domain = Ustrlen(sender_address) + 1;
5000 /* deconst ok as sender_address was not const */
5001 sender_address = US rewrite_address_qualify(sender_address, FALSE);
5002 DEBUG(D_receive) debug_printf("unqualified address %s accepted\n",
5003 raw_sender);
5004 }
5005 else
5006 {
5007 smtp_printf("501 %s: sender address must contain a domain\r\n", FALSE,
5008 smtp_cmd_data);
5009 log_write(L_smtp_syntax_error,
5010 LOG_MAIN|LOG_REJECT,
5011 "unqualified sender rejected: <%s> %s%s",
5012 raw_sender,
5013 host_and_ident(TRUE),
5014 host_lookup_msg);
5015 sender_address = NULL;
5016 break;
5017 }
5018
5019 /* Apply an ACL check if one is defined, before responding. Afterwards,
5020 when pipelining is not advertised, do another sync check in case the ACL
5021 delayed and the client started sending in the meantime. */
5022
5023 if (acl_smtp_mail)
5024 {
5025 rc = acl_check(ACL_WHERE_MAIL, NULL, acl_smtp_mail, &user_msg, &log_msg);
5026 if (rc == OK && !f.smtp_in_pipelining_advertised && !check_sync())
5027 goto SYNC_FAILURE;
5028 }
5029 else
5030 rc = OK;
5031
5032 if (rc == OK || rc == DISCARD)
5033 {
5034 BOOL more = pipeline_response();
5035
5036 if (!user_msg)
5037 smtp_printf("%s%s%s", more, US"250 OK",
5038 #ifndef DISABLE_PRDR
5039 prdr_requested ? US", PRDR Requested" : US"",
5040 #else
5041 US"",
5042 #endif
5043 US"\r\n");
5044 else
5045 {
5046 #ifndef DISABLE_PRDR
5047 if (prdr_requested)
5048 user_msg = string_sprintf("%s%s", user_msg, US", PRDR Requested");
5049 #endif
5050 smtp_user_msg(US"250", user_msg);
5051 }
5052 smtp_delay_rcpt = smtp_rlr_base;
5053 f.recipients_discarded = (rc == DISCARD);
5054 was_rej_mail = FALSE;
5055 }
5056 else
5057 {
5058 done = smtp_handle_acl_fail(ACL_WHERE_MAIL, rc, user_msg, log_msg);
5059 sender_address = NULL;
5060 }
5061 break;
5062
5063
5064 /* The RCPT command requires an address as an operand. There may be any
5065 number of RCPT commands, specifying multiple recipients. We build them all
5066 into a data structure. The start/end values given by parse_extract_address
5067 are not used, as we keep only the extracted address. */
5068
5069 case RCPT_CMD:
5070 HAD(SCH_RCPT);
5071 /* We got really to many recipients. A check against configured
5072 limits is done later */
5073 if (rcpt_count < 0 || rcpt_count >= INT_MAX/2)
5074 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "Too many recipients: %d", rcpt_count);
5075 rcpt_count++;
5076 was_rcpt = fl.rcpt_in_progress = TRUE;
5077
5078 /* There must be a sender address; if the sender was rejected and
5079 pipelining was advertised, we assume the client was pipelining, and do not
5080 count this as a protocol error. Reset was_rej_mail so that further RCPTs
5081 get the same treatment. */
5082
5083 if (sender_address == NULL)
5084 {
5085 if (f.smtp_in_pipelining_advertised && last_was_rej_mail)
5086 {
5087 smtp_printf("503 sender not yet given\r\n", FALSE);
5088 was_rej_mail = TRUE;
5089 }
5090 else
5091 {
5092 done = synprot_error(L_smtp_protocol_error, 503, NULL,
5093 US"sender not yet given");
5094 was_rcpt = FALSE; /* Not a valid RCPT */
5095 }
5096 rcpt_fail_count++;
5097 break;
5098 }
5099
5100 /* Check for an operand */
5101
5102 if (smtp_cmd_data[0] == 0)
5103 {
5104 done = synprot_error(L_smtp_syntax_error, 501, NULL,
5105 US"RCPT must have an address operand");
5106 rcpt_fail_count++;
5107 break;
5108 }
5109
5110 /* Set the DSN flags orcpt and dsn_flags from the session*/
5111 orcpt = NULL;
5112 dsn_flags = 0;
5113
5114 if (fl.esmtp) for(;;)
5115 {
5116 uschar *name, *value;
5117
5118 if (!extract_option(&name, &value))
5119 break;
5120
5121 if (fl.dsn_advertised && strcmpic(name, US"ORCPT") == 0)
5122 {
5123 /* Check whether orcpt has been already set */
5124 if (orcpt)
5125 {
5126 done = synprot_error(L_smtp_syntax_error, 501, NULL,
5127 US"ORCPT can be specified once only");
5128 goto COMMAND_LOOP;
5129 }
5130 orcpt = string_copy(value);
5131 DEBUG(D_receive) debug_printf("DSN orcpt: %s\n", orcpt);
5132 }
5133
5134 else if (fl.dsn_advertised && strcmpic(name, US"NOTIFY") == 0)
5135 {
5136 /* Check if the notify flags have been already set */
5137 if (dsn_flags > 0)
5138 {
5139 done = synprot_error(L_smtp_syntax_error, 501, NULL,
5140 US"NOTIFY can be specified once only");
5141 goto COMMAND_LOOP;
5142 }
5143 if (strcmpic(value, US"NEVER") == 0)
5144 dsn_flags |= rf_notify_never;
5145 else
5146 {
5147 uschar *p = value;
5148 while (*p != 0)
5149 {
5150 uschar *pp = p;
5151 while (*pp != 0 && *pp != ',') pp++;
5152 if (*pp == ',') *pp++ = 0;
5153 if (strcmpic(p, US"SUCCESS") == 0)
5154 {
5155 DEBUG(D_receive) debug_printf("DSN: Setting notify success\n");
5156 dsn_flags |= rf_notify_success;
5157 }
5158 else if (strcmpic(p, US"FAILURE") == 0)
5159 {
5160 DEBUG(D_receive) debug_printf("DSN: Setting notify failure\n");
5161 dsn_flags |= rf_notify_failure;
5162 }
5163 else if (strcmpic(p, US"DELAY") == 0)
5164 {
5165 DEBUG(D_receive) debug_printf("DSN: Setting notify delay\n");
5166 dsn_flags |= rf_notify_delay;
5167 }
5168 else
5169 {
5170 /* Catch any strange values */
5171 done = synprot_error(L_smtp_syntax_error, 501, NULL,
5172 US"Invalid value for NOTIFY parameter");
5173 goto COMMAND_LOOP;
5174 }
5175 p = pp;
5176 }
5177 DEBUG(D_receive) debug_printf("DSN Flags: %x\n", dsn_flags);
5178 }
5179 }
5180
5181 /* Unknown option. Stick back the terminator characters and break
5182 the loop. An error for a malformed address will occur. */
5183
5184 else
5185 {
5186 DEBUG(D_receive) debug_printf("Invalid RCPT option: %s : %s\n", name, value);
5187 name[-1] = ' ';
5188 value[-1] = '=';
5189 break;
5190 }
5191 }
5192
5193 /* Apply SMTP rewriting then extract the working address. Don't allow "<>"
5194 as a recipient address */
5195
5196 recipient = rewrite_existflags & rewrite_smtp
5197 /* deconst ok as smtp_cmd_data was not const */
5198 ? US rewrite_one(smtp_cmd_data, rewrite_smtp, NULL, FALSE, US"",
5199 global_rewrite_rules)
5200 : smtp_cmd_data;
5201
5202 if (!(recipient = parse_extract_address(recipient, &errmess, &start, &end,
5203 &recipient_domain, FALSE)))
5204 {
5205 done = synprot_error(L_smtp_syntax_error, 501, smtp_cmd_data, errmess);
5206 rcpt_fail_count++;
5207 break;
5208 }
5209
5210 /* If the recipient address is unqualified, reject it, unless this is a
5211 locally generated message. However, unqualified addresses are permitted
5212 from a configured list of hosts and nets - typically when behaving as
5213 MUAs rather than MTAs. Sad that SMTP is used for both types of traffic,
5214 really. The flag is set at the start of the SMTP connection.
5215
5216 RFC 1123 talks about supporting "the reserved mailbox postmaster"; I always
5217 assumed this meant "reserved local part", but the revision of RFC 821 and
5218 friends now makes it absolutely clear that it means *mailbox*. Consequently
5219 we must always qualify this address, regardless. */
5220
5221 if (!recipient_domain)
5222 if (!(recipient_domain = qualify_recipient(&recipient, smtp_cmd_data,
5223 US"recipient")))
5224 {
5225 rcpt_fail_count++;
5226 break;
5227 }
5228
5229 /* Check maximum allowed */
5230
5231 if (rcpt_count+1 < 0 || rcpt_count > recipients_max && recipients_max > 0)
5232 {
5233 if (recipients_max_reject)
5234 {
5235 rcpt_fail_count++;
5236 smtp_printf("552 too many recipients\r\n", FALSE);
5237 if (!toomany)
5238 log_write(0, LOG_MAIN|LOG_REJECT, "too many recipients: message "
5239 "rejected: sender=<%s> %s", sender_address, host_and_ident(TRUE));
5240 }
5241 else
5242 {
5243 rcpt_defer_count++;
5244 smtp_printf("452 too many recipients\r\n", FALSE);
5245 if (!toomany)
5246 log_write(0, LOG_MAIN|LOG_REJECT, "too many recipients: excess "
5247 "temporarily rejected: sender=<%s> %s", sender_address,
5248 host_and_ident(TRUE));
5249 }
5250
5251 toomany = TRUE;
5252 break;
5253 }
5254
5255 /* If we have passed the threshold for rate limiting, apply the current
5256 delay, and update it for next time, provided this is a limited host. */
5257
5258 if (rcpt_count > smtp_rlr_threshold &&
5259 verify_check_host(&smtp_ratelimit_hosts) == OK)
5260 {
5261 DEBUG(D_receive) debug_printf("rate limit RCPT: delay %.3g sec\n",
5262 smtp_delay_rcpt/1000.0);
5263 millisleep((int)smtp_delay_rcpt);
5264 smtp_delay_rcpt *= smtp_rlr_factor;
5265 if (smtp_delay_rcpt > (double)smtp_rlr_limit)
5266 smtp_delay_rcpt = (double)smtp_rlr_limit;
5267 }
5268
5269 /* If the MAIL ACL discarded all the recipients, we bypass ACL checking
5270 for them. Otherwise, check the access control list for this recipient. As
5271 there may be a delay in this, re-check for a synchronization error
5272 afterwards, unless pipelining was advertised. */
5273
5274 if (f.recipients_discarded)
5275 rc = DISCARD;
5276 else
5277 if ( (rc = acl_check(ACL_WHERE_RCPT, recipient, acl_smtp_rcpt, &user_msg,
5278 &log_msg)) == OK
5279 && !f.smtp_in_pipelining_advertised && !check_sync())
5280 goto SYNC_FAILURE;
5281
5282 /* The ACL was happy */
5283
5284 if (rc == OK)
5285 {
5286 BOOL more = pipeline_response();
5287
5288 if (user_msg)
5289 smtp_user_msg(US"250", user_msg);
5290 else
5291 smtp_printf("250 Accepted\r\n", more);
5292 receive_add_recipient(recipient, -1);
5293
5294 /* Set the dsn flags in the recipients_list */
5295 recipients_list[recipients_count-1].orcpt = orcpt;
5296 recipients_list[recipients_count-1].dsn_flags = dsn_flags;
5297
5298 /* DEBUG(D_receive) debug_printf("DSN: orcpt: %s flags: %d\n",
5299 recipients_list[recipients_count-1].orcpt,
5300 recipients_list[recipients_count-1].dsn_flags); */
5301 }
5302
5303 /* The recipient was discarded */
5304
5305 else if (rc == DISCARD)
5306 {
5307 if (user_msg)
5308 smtp_user_msg(US"250", user_msg);
5309 else
5310 smtp_printf("250 Accepted\r\n", FALSE);
5311 rcpt_fail_count++;
5312 discarded = TRUE;
5313 log_write(0, LOG_MAIN|LOG_REJECT, "%s F=<%s> RCPT %s: "
5314 "discarded by %s ACL%s%s", host_and_ident(TRUE),
5315 sender_address_unrewritten ? sender_address_unrewritten : sender_address,
5316 smtp_cmd_argument, f.recipients_discarded ? "MAIL" : "RCPT",
5317 log_msg ? US": " : US"", log_msg ? log_msg : US"");
5318 }
5319
5320 /* Either the ACL failed the address, or it was deferred. */
5321
5322 else
5323 {
5324 if (rc == FAIL) rcpt_fail_count++; else rcpt_defer_count++;
5325 done = smtp_handle_acl_fail(ACL_WHERE_RCPT, rc, user_msg, log_msg);
5326 }
5327 break;
5328
5329
5330 /* The DATA command is legal only if it follows successful MAIL FROM
5331 and RCPT TO commands. However, if pipelining is advertised, a bad DATA is
5332 not counted as a protocol error if it follows RCPT (which must have been
5333 rejected if there are no recipients.) This function is complete when a
5334 valid DATA command is encountered.
5335
5336 Note concerning the code used: RFC 2821 says this:
5337
5338 - If there was no MAIL, or no RCPT, command, or all such commands
5339 were rejected, the server MAY return a "command out of sequence"
5340 (503) or "no valid recipients" (554) reply in response to the
5341 DATA command.
5342
5343 The example in the pipelining RFC 2920 uses 554, but I use 503 here
5344 because it is the same whether pipelining is in use or not.
5345
5346 If all the RCPT commands that precede DATA provoked the same error message
5347 (often indicating some kind of system error), it is helpful to include it
5348 with the DATA rejection (an idea suggested by Tony Finch). */
5349
5350 case BDAT_CMD:
5351 {
5352 int n;
5353
5354 HAD(SCH_BDAT);
5355 if (chunking_state != CHUNKING_OFFERED)
5356 {
5357 done = synprot_error(L_smtp_protocol_error, 503, NULL,
5358 US"BDAT command used when CHUNKING not advertised");
5359 break;
5360 }
5361
5362 /* grab size, endmarker */
5363
5364 if (sscanf(CS smtp_cmd_data, "%u %n", &chunking_datasize, &n) < 1)
5365 {
5366 done = synprot_error(L_smtp_protocol_error, 501, NULL,
5367 US"missing size for BDAT command");
5368 break;
5369 }
5370 chunking_state = strcmpic(smtp_cmd_data+n, US"LAST") == 0
5371 ? CHUNKING_LAST : CHUNKING_ACTIVE;
5372 chunking_data_left = chunking_datasize;
5373 DEBUG(D_receive) debug_printf("chunking state %d, %d bytes\n",
5374 (int)chunking_state, chunking_data_left);
5375
5376 f.bdat_readers_wanted = TRUE; /* FIXME: redundant vs chunking_state? */
5377 f.dot_ends = FALSE;
5378
5379 goto DATA_BDAT;
5380 }
5381
5382 case DATA_CMD:
5383 HAD(SCH_DATA);
5384 f.dot_ends = TRUE;
5385 f.bdat_readers_wanted = FALSE;
5386
5387 DATA_BDAT: /* Common code for DATA and BDAT */
5388 #ifndef DISABLE_PIPE_CONNECT
5389 fl.pipe_connect_acceptable = FALSE;
5390 #endif
5391 if (!discarded && recipients_count <= 0)
5392 {
5393 if (fl.rcpt_smtp_response_same && rcpt_smtp_response != NULL)
5394 {
5395 uschar *code = US"503";
5396 int len = Ustrlen(rcpt_smtp_response);
5397 smtp_respond(code, 3, FALSE, US"All RCPT commands were rejected with "
5398 "this error:");
5399 /* Responses from smtp_printf() will have \r\n on the end */
5400 if (len > 2 && rcpt_smtp_response[len-2] == '\r')
5401 rcpt_smtp_response[len-2] = 0;
5402 smtp_respond(code, 3, FALSE, rcpt_smtp_response);
5403 }
5404 if (f.smtp_in_pipelining_advertised && last_was_rcpt)
5405 smtp_printf("503 Valid RCPT command must precede %s\r\n", FALSE,
5406 smtp_names[smtp_connection_had[SMTP_HBUFF_PREV(smtp_ch_index)]]);
5407 else
5408 done = synprot_error(L_smtp_protocol_error, 503, NULL,
5409 smtp_connection_had[SMTP_HBUFF_PREV(smtp_ch_index)] == SCH_DATA
5410 ? US"valid RCPT command must precede DATA"
5411 : US"valid RCPT command must precede BDAT");
5412
5413 if (chunking_state > CHUNKING_OFFERED)
5414 {
5415 bdat_push_receive_functions();
5416 bdat_flush_data();
5417 }
5418 break;
5419 }
5420
5421 if (toomany && recipients_max_reject)
5422 {
5423 sender_address = NULL; /* This will allow a new MAIL without RSET */
5424 sender_address_unrewritten = NULL;
5425 smtp_printf("554 Too many recipients\r\n", FALSE);
5426
5427 if (chunking_state > CHUNKING_OFFERED)
5428 {
5429 bdat_push_receive_functions();
5430 bdat_flush_data();
5431 }
5432 break;
5433 }
5434
5435 if (chunking_state > CHUNKING_OFFERED)
5436 rc = OK; /* No predata ACL or go-ahead output for BDAT */
5437 else
5438 {
5439 /* If there is an ACL, re-check the synchronization afterwards, since the
5440 ACL may have delayed. To handle cutthrough delivery enforce a dummy call
5441 to get the DATA command sent. */
5442
5443 if (acl_smtp_predata == NULL && cutthrough.cctx.sock < 0)
5444 rc = OK;
5445 else
5446 {
5447 uschar * acl = acl_smtp_predata ? acl_smtp_predata : US"accept";
5448 f.enable_dollar_recipients = TRUE;
5449 rc = acl_check(ACL_WHERE_PREDATA, NULL, acl, &user_msg,
5450 &log_msg);
5451 f.enable_dollar_recipients = FALSE;
5452 if (rc == OK && !check_sync())
5453 goto SYNC_FAILURE;
5454
5455 if (rc != OK)
5456 { /* Either the ACL failed the address, or it was deferred. */
5457 done = smtp_handle_acl_fail(ACL_WHERE_PREDATA, rc, user_msg, log_msg);
5458 break;
5459 }
5460 }
5461
5462 if (user_msg)
5463 smtp_user_msg(US"354", user_msg);
5464 else
5465 smtp_printf(
5466 "354 Enter message, ending with \".\" on a line by itself\r\n", FALSE);
5467 }
5468
5469 if (f.bdat_readers_wanted)
5470 bdat_push_receive_functions();
5471
5472 #ifdef TCP_QUICKACK
5473 if (smtp_in) /* all ACKs needed to ramp window up for bulk data */
5474 (void) setsockopt(fileno(smtp_in), IPPROTO_TCP, TCP_QUICKACK,
5475 US &on, sizeof(on));
5476 #endif
5477 done = 3;
5478 message_ended = END_NOTENDED; /* Indicate in middle of data */
5479
5480 break;
5481
5482
5483 case VRFY_CMD:
5484 {
5485 uschar * address;
5486
5487 HAD(SCH_VRFY);
5488
5489 if (!(address = parse_extract_address(smtp_cmd_data, &errmess,
5490 &start, &end, &recipient_domain, FALSE)))
5491 {
5492 smtp_printf("501 %s\r\n", FALSE, errmess);
5493 break;
5494 }
5495
5496 if (!recipient_domain)
5497 if (!(recipient_domain = qualify_recipient(&address, smtp_cmd_data,
5498 US"verify")))
5499 break;
5500
5501 if ((rc = acl_check(ACL_WHERE_VRFY, address, acl_smtp_vrfy,
5502 &user_msg, &log_msg)) != OK)
5503 done = smtp_handle_acl_fail(ACL_WHERE_VRFY, rc, user_msg, log_msg);
5504 else
5505 {
5506 uschar * s = NULL;
5507 address_item * addr = deliver_make_addr(address, FALSE);
5508
5509 switch(verify_address(addr, NULL, vopt_is_recipient | vopt_qualify, -1,
5510 -1, -1, NULL, NULL, NULL))
5511 {
5512 case OK:
5513 s = string_sprintf("250 <%s> is deliverable", address);
5514 break;
5515
5516 case DEFER:
5517 s = (addr->user_message != NULL)?
5518 string_sprintf("451 <%s> %s", address, addr->user_message) :
5519 string_sprintf("451 Cannot resolve <%s> at this time", address);
5520 break;
5521
5522 case FAIL:
5523 s = (addr->user_message != NULL)?
5524 string_sprintf("550 <%s> %s", address, addr->user_message) :
5525 string_sprintf("550 <%s> is not deliverable", address);
5526 log_write(0, LOG_MAIN, "VRFY failed for %s %s",
5527 smtp_cmd_argument, host_and_ident(TRUE));
5528 break;
5529 }
5530
5531 smtp_printf("%s\r\n", FALSE, s);
5532 }
5533 break;
5534 }
5535
5536
5537 case EXPN_CMD:
5538 HAD(SCH_EXPN);
5539 rc = acl_check(ACL_WHERE_EXPN, NULL, acl_smtp_expn, &user_msg, &log_msg);
5540 if (rc != OK)
5541 done = smtp_handle_acl_fail(ACL_WHERE_EXPN, rc, user_msg, log_msg);
5542 else
5543 {
5544 BOOL save_log_testing_mode = f.log_testing_mode;
5545 f.address_test_mode = f.log_testing_mode = TRUE;
5546 (void) verify_address(deliver_make_addr(smtp_cmd_data, FALSE),
5547 smtp_out, vopt_is_recipient | vopt_qualify | vopt_expn, -1, -1, -1,
5548 NULL, NULL, NULL);
5549 f.address_test_mode = FALSE;
5550 f.log_testing_mode = save_log_testing_mode; /* true for -bh */
5551 }
5552 break;
5553
5554
5555 #ifndef DISABLE_TLS
5556
5557 case STARTTLS_CMD:
5558 HAD(SCH_STARTTLS);
5559 if (!fl.tls_advertised)
5560 {
5561 done = synprot_error(L_smtp_protocol_error, 503, NULL,
5562 US"STARTTLS command used when not advertised");
5563 break;
5564 }
5565
5566 /* Apply an ACL check if one is defined */
5567
5568 if ( acl_smtp_starttls
5569 && (rc = acl_check(ACL_WHERE_STARTTLS, NULL, acl_smtp_starttls,
5570 &user_msg, &log_msg)) != OK
5571 )
5572 {
5573 done = smtp_handle_acl_fail(ACL_WHERE_STARTTLS, rc, user_msg, log_msg);
5574 break;
5575 }
5576
5577 /* RFC 2487 is not clear on when this command may be sent, though it
5578 does state that all information previously obtained from the client
5579 must be discarded if a TLS session is started. It seems reasonable to
5580 do an implied RSET when STARTTLS is received. */
5581
5582 incomplete_transaction_log(US"STARTTLS");
5583 cancel_cutthrough_connection(TRUE, US"STARTTLS received");
5584 reset_point = smtp_reset(reset_point);
5585 toomany = FALSE;
5586 cmd_list[CMD_LIST_STARTTLS].is_mail_cmd = FALSE;
5587
5588 /* There's an attack where more data is read in past the STARTTLS command
5589 before TLS is negotiated, then assumed to be part of the secure session
5590 when used afterwards; we use segregated input buffers, so are not
5591 vulnerable, but we want to note when it happens and, for sheer paranoia,
5592 ensure that the buffer is "wiped".
5593 Pipelining sync checks will normally have protected us too, unless disabled
5594 by configuration. */
5595
5596 if (receive_smtp_buffered())
5597 {
5598 DEBUG(D_any)
5599 debug_printf("Non-empty input buffer after STARTTLS; naive attack?\n");
5600 if (tls_in.active.sock < 0)
5601 smtp_inend = smtp_inptr = smtp_inbuffer;
5602 /* and if TLS is already active, tls_server_start() should fail */
5603 }
5604
5605 /* There is nothing we value in the input buffer and if TLS is successfully
5606 negotiated, we won't use this buffer again; if TLS fails, we'll just read
5607 fresh content into it. The buffer contains arbitrary content from an
5608 untrusted remote source; eg: NOOP <shellcode>\r\nSTARTTLS\r\n
5609 It seems safest to just wipe away the content rather than leave it as a
5610 target to jump to. */
5611
5612 memset(smtp_inbuffer, 0, IN_BUFFER_SIZE);
5613
5614 /* Attempt to start up a TLS session, and if successful, discard all
5615 knowledge that was obtained previously. At least, that's what the RFC says,
5616 and that's what happens by default. However, in order to work round YAEB,
5617 there is an option to remember the esmtp state. Sigh.
5618
5619 We must allow for an extra EHLO command and an extra AUTH command after
5620 STARTTLS that don't add to the nonmail command count. */
5621
5622 s = NULL;
5623 if ((rc = tls_server_start(&s)) == OK)
5624 {
5625 if (!tls_remember_esmtp)
5626 fl.helo_seen = fl.esmtp = fl.auth_advertised = f.smtp_in_pipelining_advertised = FALSE;
5627 cmd_list[CMD_LIST_EHLO].is_mail_cmd = TRUE;
5628 cmd_list[CMD_LIST_AUTH].is_mail_cmd = TRUE;
5629 cmd_list[CMD_LIST_TLS_AUTH].is_mail_cmd = TRUE;
5630 if (sender_helo_name)
5631 {
5632 sender_helo_name = NULL;
5633 host_build_sender_fullhost(); /* Rebuild */
5634 set_process_info("handling incoming TLS connection from %s",
5635 host_and_ident(FALSE));
5636 }
5637 received_protocol =
5638 (sender_host_address ? protocols : protocols_local)
5639 [ (fl.esmtp
5640 ? pextend + (sender_host_authenticated ? pauthed : 0)
5641 : pnormal)
5642 + (tls_in.active.sock >= 0 ? pcrpted : 0)
5643 ];
5644
5645 sender_host_auth_pubname = sender_host_authenticated = NULL;
5646 authenticated_id = NULL;
5647 sync_cmd_limit = NON_SYNC_CMD_NON_PIPELINING;
5648 DEBUG(D_tls) debug_printf("TLS active\n");
5649 break; /* Successful STARTTLS */
5650 }
5651 else
5652 (void) smtp_log_tls_fail(s);
5653
5654 /* Some local configuration problem was discovered before actually trying
5655 to do a TLS handshake; give a temporary error. */
5656
5657 if (rc == DEFER)
5658 {
5659 smtp_printf("454 TLS currently unavailable\r\n", FALSE);
5660 break;
5661 }
5662
5663 /* Hard failure. Reject everything except QUIT or closed connection. One
5664 cause for failure is a nested STARTTLS, in which case tls_in.active remains
5665 set, but we must still reject all incoming commands. Another is a handshake
5666 failure - and there may some encrypted data still in the pipe to us, which we
5667 see as garbage commands. */
5668
5669 DEBUG(D_tls) debug_printf("TLS failed to start\n");
5670 while (done <= 0) switch(smtp_read_command(FALSE, GETC_BUFFER_UNLIMITED))
5671 {
5672 case EOF_CMD:
5673 log_write(L_smtp_connection, LOG_MAIN, "%s closed by EOF",
5674 smtp_get_connection_info());
5675 smtp_notquit_exit(US"tls-failed", NULL, NULL);
5676 done = 2;
5677 break;
5678
5679 /* It is perhaps arguable as to which exit ACL should be called here,
5680 but as it is probably a situation that almost never arises, it
5681 probably doesn't matter. We choose to call the real QUIT ACL, which in
5682 some sense is perhaps "right". */
5683
5684 case QUIT_CMD:
5685 f.smtp_in_quit = TRUE;
5686 user_msg = NULL;
5687 if ( acl_smtp_quit
5688 && ((rc = acl_check(ACL_WHERE_QUIT, NULL, acl_smtp_quit, &user_msg,
5689 &log_msg)) == ERROR))
5690 log_write(0, LOG_MAIN|LOG_PANIC, "ACL for QUIT returned ERROR: %s",
5691 log_msg);
5692 if (user_msg)
5693 smtp_respond(US"221", 3, TRUE, user_msg);
5694 else
5695 smtp_printf("221 %s closing connection\r\n", FALSE, smtp_active_hostname);
5696 log_write(L_smtp_connection, LOG_MAIN, "%s closed by QUIT",
5697 smtp_get_connection_info());
5698 done = 2;
5699 break;
5700
5701 default:
5702 smtp_printf("554 Security failure\r\n", FALSE);
5703 break;
5704 }
5705 tls_close(NULL, TLS_SHUTDOWN_NOWAIT);
5706 break;
5707 #endif
5708
5709
5710 /* The ACL for QUIT is provided for gathering statistical information or
5711 similar; it does not affect the response code, but it can supply a custom
5712 message. */
5713
5714 case QUIT_CMD:
5715 smtp_quit_handler(&user_msg, &log_msg);
5716 done = 2;
5717 break;
5718
5719
5720 case RSET_CMD:
5721 smtp_rset_handler();
5722 cancel_cutthrough_connection(TRUE, US"RSET received");
5723 reset_point = smtp_reset(reset_point);
5724 toomany = FALSE;
5725 break;
5726
5727
5728 case NOOP_CMD:
5729 HAD(SCH_NOOP);
5730 smtp_printf("250 OK\r\n", FALSE);
5731 break;
5732
5733
5734 /* Show ETRN/EXPN/VRFY if there's an ACL for checking hosts; if actually
5735 used, a check will be done for permitted hosts. Show STARTTLS only if not
5736 already in a TLS session and if it would be advertised in the EHLO
5737 response. */
5738
5739 case HELP_CMD:
5740 HAD(SCH_HELP);
5741 smtp_printf("214-Commands supported:\r\n", TRUE);
5742 {
5743 uschar buffer[256];
5744 buffer[0] = 0;
5745 Ustrcat(buffer, US" AUTH");
5746 #ifndef DISABLE_TLS
5747 if (tls_in.active.sock < 0 &&
5748 verify_check_host(&tls_advertise_hosts) != FAIL)
5749 Ustrcat(buffer, US" STARTTLS");
5750 #endif
5751 Ustrcat(buffer, US" HELO EHLO MAIL RCPT DATA BDAT");
5752 Ustrcat(buffer, US" NOOP QUIT RSET HELP");
5753 if (acl_smtp_etrn) Ustrcat(buffer, US" ETRN");
5754 if (acl_smtp_expn) Ustrcat(buffer, US" EXPN");
5755 if (acl_smtp_vrfy) Ustrcat(buffer, US" VRFY");
5756 smtp_printf("214%s\r\n", FALSE, buffer);
5757 }
5758 break;
5759
5760
5761 case EOF_CMD:
5762 incomplete_transaction_log(US"connection lost");
5763 smtp_notquit_exit(US"connection-lost", US"421",
5764 US"%s lost input connection", smtp_active_hostname);
5765
5766 /* Don't log by default unless in the middle of a message, as some mailers
5767 just drop the call rather than sending QUIT, and it clutters up the logs.
5768 */
5769
5770 if (sender_address || recipients_count > 0)
5771 log_write(L_lost_incoming_connection, LOG_MAIN,
5772 "unexpected %s while reading SMTP command from %s%s%s D=%s",
5773 f.sender_host_unknown ? "EOF" : "disconnection",
5774 f.tcp_in_fastopen_logged
5775 ? US""
5776 : f.tcp_in_fastopen
5777 ? f.tcp_in_fastopen_data ? US"TFO* " : US"TFO "
5778 : US"",
5779 host_and_ident(FALSE), smtp_read_error,
5780 string_timesince(&smtp_connection_start)
5781 );
5782
5783 else
5784 log_write(L_smtp_connection, LOG_MAIN, "%s %slost%s D=%s",
5785 smtp_get_connection_info(),
5786 f.tcp_in_fastopen && !f.tcp_in_fastopen_logged ? US"TFO " : US"",
5787 smtp_read_error,
5788 string_timesince(&smtp_connection_start)
5789 );
5790
5791 done = 1;
5792 break;
5793
5794
5795 case ETRN_CMD:
5796 HAD(SCH_ETRN);
5797 if (sender_address)
5798 {
5799 done = synprot_error(L_smtp_protocol_error, 503, NULL,
5800 US"ETRN is not permitted inside a transaction");
5801 break;
5802 }
5803
5804 log_write(L_etrn, LOG_MAIN, "ETRN %s received from %s", smtp_cmd_argument,
5805 host_and_ident(FALSE));
5806
5807 if ((rc = acl_check(ACL_WHERE_ETRN, NULL, acl_smtp_etrn,
5808 &user_msg, &log_msg)) != OK)
5809 {
5810 done = smtp_handle_acl_fail(ACL_WHERE_ETRN, rc, user_msg, log_msg);
5811 break;
5812 }
5813
5814 /* Compute the serialization key for this command. */
5815
5816 etrn_serialize_key = string_sprintf("etrn-%s\n", smtp_cmd_data);
5817
5818 /* If a command has been specified for running as a result of ETRN, we
5819 permit any argument to ETRN. If not, only the # standard form is permitted,
5820 since that is strictly the only kind of ETRN that can be implemented
5821 according to the RFC. */
5822
5823 if (smtp_etrn_command)
5824 {
5825 uschar *error;
5826 BOOL rc;
5827 etrn_command = smtp_etrn_command;
5828 deliver_domain = smtp_cmd_data;
5829 rc = transport_set_up_command(&argv, smtp_etrn_command, TRUE, 0, NULL,
5830 US"ETRN processing", &error);
5831 deliver_domain = NULL;
5832 if (!rc)
5833 {
5834 log_write(0, LOG_MAIN|LOG_PANIC, "failed to set up ETRN command: %s",
5835 error);
5836 smtp_printf("458 Internal failure\r\n", FALSE);
5837 break;
5838 }
5839 }
5840
5841 /* Else set up to call Exim with the -R option. */
5842
5843 else
5844 {
5845 if (*smtp_cmd_data++ != '#')
5846 {
5847 done = synprot_error(L_smtp_syntax_error, 501, NULL,
5848 US"argument must begin with #");
5849 break;
5850 }
5851 etrn_command = US"exim -R";
5852 argv = CUSS child_exec_exim(CEE_RETURN_ARGV, TRUE, NULL, TRUE,
5853 *queue_name ? 4 : 2,
5854 US"-R", smtp_cmd_data,
5855 US"-MCG", queue_name);
5856 }
5857
5858 /* If we are host-testing, don't actually do anything. */
5859
5860 if (host_checking)
5861 {
5862 HDEBUG(D_any)
5863 {
5864 debug_printf("ETRN command is: %s\n", etrn_command);
5865 debug_printf("ETRN command execution skipped\n");
5866 }
5867 if (user_msg == NULL) smtp_printf("250 OK\r\n", FALSE);
5868 else smtp_user_msg(US"250", user_msg);
5869 break;
5870 }
5871
5872
5873 /* If ETRN queue runs are to be serialized, check the database to
5874 ensure one isn't already running. */
5875
5876 if (smtp_etrn_serialize && !enq_start(etrn_serialize_key, 1))
5877 {
5878 smtp_printf("458 Already processing %s\r\n", FALSE, smtp_cmd_data);
5879 break;
5880 }
5881
5882 /* Fork a child process and run the command. We don't want to have to
5883 wait for the process at any point, so set SIGCHLD to SIG_IGN before
5884 forking. It should be set that way anyway for external incoming SMTP,
5885 but we save and restore to be tidy. If serialization is required, we
5886 actually run the command in yet another process, so we can wait for it
5887 to complete and then remove the serialization lock. */
5888
5889 oldsignal = signal(SIGCHLD, SIG_IGN);
5890
5891 if ((pid = exim_fork(US"etrn-command")) == 0)
5892 {
5893 smtp_input = FALSE; /* This process is not associated with the */
5894 (void)fclose(smtp_in); /* SMTP call any more. */
5895 (void)fclose(smtp_out);
5896
5897 signal(SIGCHLD, SIG_DFL); /* Want to catch child */
5898
5899 /* If not serializing, do the exec right away. Otherwise, fork down
5900 into another process. */
5901
5902 if ( !smtp_etrn_serialize
5903 || (pid = exim_fork(US"etrn-serialised-command")) == 0)
5904 {
5905 DEBUG(D_exec) debug_print_argv(argv);
5906 exim_nullstd(); /* Ensure std{in,out,err} exist */
5907 execv(CS argv[0], (char *const *)argv);
5908 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "exec of \"%s\" (ETRN) failed: %s",
5909 etrn_command, strerror(errno));
5910 _exit(EXIT_FAILURE); /* paranoia */
5911 }
5912
5913 /* Obey this if smtp_serialize and the 2nd fork yielded non-zero. That
5914 is, we are in the first subprocess, after forking again. All we can do
5915 for a failing fork is to log it. Otherwise, wait for the 2nd process to
5916 complete, before removing the serialization. */
5917
5918 if (pid < 0)
5919 log_write(0, LOG_MAIN|LOG_PANIC, "2nd fork for serialized ETRN "
5920 "failed: %s", strerror(errno));
5921 else
5922 {
5923 int status;
5924 DEBUG(D_any) debug_printf("waiting for serialized ETRN process %d\n",
5925 (int)pid);
5926 (void)wait(&status);
5927 DEBUG(D_any) debug_printf("serialized ETRN process %d ended\n",
5928 (int)pid);
5929 }
5930
5931 enq_end(etrn_serialize_key);
5932 exim_underbar_exit(EXIT_SUCCESS);
5933 }
5934
5935 /* Back in the top level SMTP process. Check that we started a subprocess
5936 and restore the signal state. */
5937
5938 if (pid < 0)
5939 {
5940 log_write(0, LOG_MAIN|LOG_PANIC, "fork of process for ETRN failed: %s",
5941 strerror(errno));
5942 smtp_printf("458 Unable to fork process\r\n", FALSE);
5943 if (smtp_etrn_serialize) enq_end(etrn_serialize_key);
5944 }
5945 else
5946 if (!user_msg)
5947 smtp_printf("250 OK\r\n", FALSE);
5948 else
5949 smtp_user_msg(US"250", user_msg);
5950
5951 signal(SIGCHLD, oldsignal);
5952 break;
5953
5954
5955 case BADARG_CMD:
5956 done = synprot_error(L_smtp_syntax_error, 501, NULL,
5957 US"unexpected argument data");
5958 break;
5959
5960
5961 /* This currently happens only for NULLs, but could be extended. */
5962
5963 case BADCHAR_CMD:
5964 done = synprot_error(L_smtp_syntax_error, 0, NULL, /* Just logs */
5965 US"NUL character(s) present (shown as '?')");
5966 smtp_printf("501 NUL characters are not allowed in SMTP commands\r\n",
5967 FALSE);
5968 break;
5969
5970
5971 case BADSYN_CMD:
5972 SYNC_FAILURE:
5973 if (smtp_inend >= smtp_inbuffer + IN_BUFFER_SIZE)
5974 smtp_inend = smtp_inbuffer + IN_BUFFER_SIZE - 1;
5975 c = smtp_inend - smtp_inptr;
5976 if (c > 150) c = 150; /* limit logged amount */
5977 smtp_inptr[c] = 0;
5978 incomplete_transaction_log(US"sync failure");
5979 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP protocol synchronization error "
5980 "(next input sent too soon: pipelining was%s advertised): "
5981 "rejected \"%s\" %s next input=\"%s\"",
5982 f.smtp_in_pipelining_advertised ? "" : " not",
5983 smtp_cmd_buffer, host_and_ident(TRUE),
5984 string_printing(smtp_inptr));
5985 smtp_notquit_exit(US"synchronization-error", US"554",
5986 US"SMTP synchronization error");
5987 done = 1; /* Pretend eof - drops connection */
5988 break;
5989
5990
5991 case TOO_MANY_NONMAIL_CMD:
5992 s = smtp_cmd_buffer;
5993 while (*s != 0 && !isspace(*s)) s++;
5994 incomplete_transaction_log(US"too many non-mail commands");
5995 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
5996 "nonmail commands (last was \"%.*s\")", host_and_ident(FALSE),
5997 (int)(s - smtp_cmd_buffer), smtp_cmd_buffer);
5998 smtp_notquit_exit(US"bad-commands", US"554", US"Too many nonmail commands");
5999 done = 1; /* Pretend eof - drops connection */
6000 break;
6001
6002 #ifdef SUPPORT_PROXY
6003 case PROXY_FAIL_IGNORE_CMD:
6004 smtp_printf("503 Command refused, required Proxy negotiation failed\r\n", FALSE);
6005 break;
6006 #endif
6007
6008 default:
6009 if (unknown_command_count++ >= smtp_max_unknown_commands)
6010 {
6011 log_write(L_smtp_syntax_error, LOG_MAIN,
6012 "SMTP syntax error in \"%s\" %s %s",
6013 string_printing(smtp_cmd_buffer), host_and_ident(TRUE),
6014 US"unrecognized command");
6015 incomplete_transaction_log(US"unrecognized command");
6016 smtp_notquit_exit(US"bad-commands", US"500",
6017 US"Too many unrecognized commands");
6018 done = 2;
6019 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
6020 "unrecognized commands (last was \"%s\")", host_and_ident(FALSE),
6021 string_printing(smtp_cmd_buffer));
6022 }
6023 else
6024 done = synprot_error(L_smtp_syntax_error, 500, NULL,
6025 US"unrecognized command");
6026 break;
6027 }
6028
6029 /* This label is used by goto's inside loops that want to break out to
6030 the end of the command-processing loop. */
6031
6032 COMMAND_LOOP:
6033 last_was_rej_mail = was_rej_mail; /* Remember some last commands for */
6034 last_was_rcpt = was_rcpt; /* protocol error handling */
6035 continue;
6036 }
6037
6038 return done - 2; /* Convert yield values */
6039 }
6040
6041
6042
6043 gstring *
authres_smtpauth(gstring * g)6044 authres_smtpauth(gstring * g)
6045 {
6046 if (!sender_host_authenticated)
6047 return g;
6048
6049 g = string_append(g, 2, US";\n\tauth=pass (", sender_host_auth_pubname);
6050
6051 if (Ustrcmp(sender_host_auth_pubname, "tls") == 0)
6052 g = authenticated_id
6053 ? string_append(g, 2, US") x509.auth=", authenticated_id)
6054 : string_cat(g, US") reason=x509.auth");
6055 else
6056 g = authenticated_id
6057 ? string_append(g, 2, US") smtp.auth=", authenticated_id)
6058 : string_cat(g, US", no id saved)");
6059
6060 if (authenticated_sender)
6061 g = string_append(g, 2, US" smtp.mailfrom=", authenticated_sender);
6062 return g;
6063 }
6064
6065
6066
6067 /* vi: aw ai sw=2
6068 */
6069 /* End of smtp_in.c */
6070