1 /* $NetBSD: transport.c,v 1.4 2022/10/08 16:12:50 christos Exp $ */
2
3 /*++
4 /* NAME
5 /* transport 3
6 /* SUMMARY
7 /* transport mapping
8 /* SYNOPSIS
9 /* #include "transport.h"
10 /*
11 /* TRANSPORT_INFO *transport_pre_init(maps_name, maps)
12 /* const char *maps_name;
13 /* const char *maps;
14 /*
15 /* void transport_post_init(info)
16 /* TRANSPORT_INFO *info;
17 /*
18 /* int transport_lookup(info, address, rcpt_domain, channel, nexthop)
19 /* TRANSPORT_INFO *info;
20 /* const char *address;
21 /* const char *rcpt_domain;
22 /* VSTRING *channel;
23 /* VSTRING *nexthop;
24 /*
25 /* void transport_free(info);
26 /* TRANSPORT_INFO * info;
27 /* DESCRIPTION
28 /* This module implements access to the table that maps transport
29 /* user@domain addresses to (channel, nexthop) tuples.
30 /*
31 /* transport_pre_init() performs initializations that should be
32 /* done before the process enters the chroot jail, and
33 /* before calling transport_lookup().
34 /*
35 /* transport_post_init() can be invoked after entering the chroot
36 /* jail, and must be called before calling transport_lookup().
37 /*
38 /* transport_lookup() finds the channel and nexthop for the given
39 /* domain, and returns 1 if something was found. Otherwise, 0
40 /* is returned.
41 /* DIAGNOSTICS
42 /* info->transport_path->error is non-zero when the lookup
43 /* should be tried again.
44 /* SEE ALSO
45 /* maps(3), multi-dictionary search
46 /* strip_addr(3), strip extension from address
47 /* transport(5), format of transport map
48 /* CONFIGURATION PARAMETERS
49 /* transport_maps, names of maps to be searched.
50 /* LICENSE
51 /* .ad
52 /* .fi
53 /* The Secure Mailer license must be distributed with this software.
54 /* AUTHOR(S)
55 /* Wietse Venema
56 /* IBM T.J. Watson Research
57 /* P.O. Box 704
58 /* Yorktown Heights, NY 10598, USA
59 /*
60 /* Wietse Venema
61 /* Google, Inc.
62 /* 111 8th Avenue
63 /* New York, NY 10011, USA
64 /*--*/
65
66 /* System library. */
67
68 #include <sys_defs.h>
69 #include <string.h>
70
71 /* Utility library. */
72
73 #include <msg.h>
74 #include <stringops.h>
75 #include <mymalloc.h>
76 #include <vstring.h>
77 #include <split_at.h>
78 #include <dict.h>
79 #include <events.h>
80
81 /* Global library. */
82
83 #include <strip_addr.h>
84 #include <mail_params.h>
85 #include <mail_addr_find.h>
86 #include <match_parent_style.h>
87 #include <mail_proto.h>
88
89 /* Application-specific. */
90
91 #include "transport.h"
92
93 static int transport_match_parent_style;
94
95 #define STR(x) vstring_str(x)
96
97 static void transport_wildcard_init(TRANSPORT_INFO *);
98
99 /* transport_pre_init - pre-jail initialization */
100
transport_pre_init(const char * transport_maps_name,const char * transport_maps)101 TRANSPORT_INFO *transport_pre_init(const char *transport_maps_name,
102 const char *transport_maps)
103 {
104 TRANSPORT_INFO *tp;
105
106 tp = (TRANSPORT_INFO *) mymalloc(sizeof(*tp));
107 tp->transport_path = maps_create(transport_maps_name, transport_maps,
108 DICT_FLAG_LOCK | DICT_FLAG_FOLD_FIX
109 | DICT_FLAG_NO_REGSUB
110 | DICT_FLAG_UTF8_REQUEST);
111 tp->wildcard_channel = tp->wildcard_nexthop = 0;
112 tp->wildcard_errno = 0;
113 tp->expire = 0;
114 return (tp);
115 }
116
117 /* transport_post_init - post-jail initialization */
118
transport_post_init(TRANSPORT_INFO * tp)119 void transport_post_init(TRANSPORT_INFO *tp)
120 {
121 transport_match_parent_style = match_parent_style(VAR_TRANSPORT_MAPS);
122 transport_wildcard_init(tp);
123 }
124
125 /* transport_free - destroy transport info */
126
transport_free(TRANSPORT_INFO * tp)127 void transport_free(TRANSPORT_INFO *tp)
128 {
129 if (tp->transport_path)
130 maps_free(tp->transport_path);
131 if (tp->wildcard_channel)
132 vstring_free(tp->wildcard_channel);
133 if (tp->wildcard_nexthop)
134 vstring_free(tp->wildcard_nexthop);
135 myfree((void *) tp);
136 }
137
138 /* update_entry - update from transport table entry */
139
update_entry(const char * new_channel,const char * new_nexthop,const char * rcpt_domain,VSTRING * channel,VSTRING * nexthop)140 static void update_entry(const char *new_channel, const char *new_nexthop,
141 const char *rcpt_domain, VSTRING *channel,
142 VSTRING *nexthop)
143 {
144
145 /*
146 * :[nexthop] means don't change the channel, and don't change the
147 * nexthop unless a non-default nexthop is specified. Thus, a right-hand
148 * side of ":" is the transport table equivalent of a NOOP.
149 */
150 if (*new_channel == 0) { /* :[nexthop] */
151 if (*new_nexthop != 0)
152 vstring_strcpy(nexthop, new_nexthop);
153 }
154
155 /*
156 * transport[:[nexthop]] means change the channel, and reset the nexthop
157 * to the default unless a non-default nexthop is specified.
158 */
159 else {
160 vstring_strcpy(channel, new_channel);
161 if (*new_nexthop != 0)
162 vstring_strcpy(nexthop, new_nexthop);
163 else if (strcmp(STR(channel), MAIL_SERVICE_ERROR) != 0
164 && strcmp(STR(channel), MAIL_SERVICE_RETRY) != 0)
165 vstring_strcpy(nexthop, rcpt_domain);
166 else
167 vstring_strcpy(nexthop, "Address is undeliverable");
168 }
169 }
170
171 /* parse_transport_entry - parse transport table entry */
172
parse_transport_entry(const char * value,const char * rcpt_domain,VSTRING * channel,VSTRING * nexthop)173 static void parse_transport_entry(const char *value, const char *rcpt_domain,
174 VSTRING *channel, VSTRING *nexthop)
175 {
176 char *saved_value;
177 const char *host;
178
179 #define FOUND 1
180 #define NOTFOUND 0
181
182 /*
183 * It would be great if we could specify a recipient address in the
184 * lookup result. Unfortunately, we cannot simply run the result through
185 * a parser that recognizes "transport:user@domain" because the lookup
186 * result can have arbitrary content (especially in the case of the error
187 * mailer).
188 */
189 saved_value = mystrdup(value);
190 host = split_at(saved_value, ':');
191 update_entry(saved_value, host ? host : "", rcpt_domain, channel, nexthop);
192 myfree(saved_value);
193 }
194
195 /* transport_wildcard_init - (re) initialize wild-card lookup result */
196
transport_wildcard_init(TRANSPORT_INFO * tp)197 static void transport_wildcard_init(TRANSPORT_INFO *tp)
198 {
199 VSTRING *channel = vstring_alloc(10);
200 VSTRING *nexthop = vstring_alloc(10);
201 const char *value;
202
203 /*
204 * Both channel and nexthop may be zero-length strings. Therefore we must
205 * use something else to represent "wild-card does not exist". We use
206 * null VSTRING pointers, for historical reasons.
207 */
208 if (tp->wildcard_channel)
209 vstring_free(tp->wildcard_channel);
210 if (tp->wildcard_nexthop)
211 vstring_free(tp->wildcard_nexthop);
212
213 /*
214 * Technically, the wildcard lookup pattern is redundant. A static map
215 * (keys always match, result is fixed string) could achieve the same:
216 *
217 * transport_maps = hash:/etc/postfix/transport static:xxx:yyy
218 *
219 * But the user interface of such an approach would be less intuitive. We
220 * tolerate the continued existence of wildcard lookup patterns because
221 * of human interface considerations.
222 */
223 #define WILDCARD "*"
224 #define FULL 0
225 #define PARTIAL DICT_FLAG_FIXED
226
227 if ((value = maps_find(tp->transport_path, WILDCARD, FULL)) != 0) {
228 parse_transport_entry(value, "", channel, nexthop);
229 tp->wildcard_errno = 0;
230 tp->wildcard_channel = channel;
231 tp->wildcard_nexthop = nexthop;
232 if (msg_verbose)
233 msg_info("wildcard_{chan:hop}={%s:%s}",
234 vstring_str(channel), vstring_str(nexthop));
235 } else {
236 tp->wildcard_errno = tp->transport_path->error;
237 vstring_free(channel);
238 vstring_free(nexthop);
239 tp->wildcard_channel = 0;
240 tp->wildcard_nexthop = 0;
241 }
242 tp->expire = event_time() + 30; /* XXX make configurable */
243 }
244
245 /* transport_lookup - map a transport domain */
246
transport_lookup(TRANSPORT_INFO * tp,const char * addr,const char * rcpt_domain,VSTRING * channel,VSTRING * nexthop)247 int transport_lookup(TRANSPORT_INFO *tp, const char *addr,
248 const char *rcpt_domain,
249 VSTRING *channel, VSTRING *nexthop)
250 {
251 char *ratsign = 0;
252 const char *value;
253
254 #define STREQ(x,y) (strcmp((x), (y)) == 0)
255 #define DISCARD_EXTENSION ((char **) 0)
256
257 /*
258 * The null recipient is rewritten to the local mailer daemon address.
259 */
260 if (*addr == 0) {
261 msg_warn("transport_lookup: null address - skipping table lookup");
262 return (NOTFOUND);
263 }
264
265 /*
266 * Look up the full and extension-stripped address, then match the domain
267 * and subdomains. Try the external form before the backwards-compatible
268 * internal form.
269 */
270 #define LOOKUP_STRATEGY \
271 (MA_FIND_FULL | MA_FIND_NOEXT | MA_FIND_DOMAIN | \
272 (transport_match_parent_style == MATCH_FLAG_PARENT ? \
273 MA_FIND_PDMS : MA_FIND_PDDMDS))
274
275 if ((ratsign = strrchr(addr, '@')) == 0 || ratsign[1] == 0)
276 msg_panic("transport_lookup: bad address: \"%s\"", addr);
277
278 if ((value = mail_addr_find_strategy(tp->transport_path, addr, (char **) 0,
279 LOOKUP_STRATEGY)) != 0) {
280 parse_transport_entry(value, rcpt_domain, channel, nexthop);
281 return (FOUND);
282 }
283 if (tp->transport_path->error != 0)
284 return (NOTFOUND);
285
286 /*
287 * Fall back to the wild-card entry.
288 */
289 if (tp->wildcard_errno || event_time() > tp->expire)
290 transport_wildcard_init(tp);
291 if (tp->wildcard_errno) {
292 tp->transport_path->error = tp->wildcard_errno;
293 return (NOTFOUND);
294 } else if (tp->wildcard_channel) {
295 update_entry(STR(tp->wildcard_channel), STR(tp->wildcard_nexthop),
296 rcpt_domain, channel, nexthop);
297 return (FOUND);
298 }
299
300 /*
301 * We really did not find it.
302 */
303 return (NOTFOUND);
304 }
305
306 #ifdef TEST
307
308 /*
309 * Proof-of-concept test program. Read an address from stdin, and spit out
310 * the lookup result.
311 */
312
313 #include <string.h>
314
315 #include <mail_conf.h>
316 #include <vstream.h>
317 #include <vstring_vstream.h>
318
usage(const char * progname)319 static NORETURN usage(const char *progname)
320 {
321 msg_fatal("usage: %s [-v] database", progname);
322 }
323
main(int argc,char ** argv)324 int main(int argc, char **argv)
325 {
326 VSTRING *buffer = vstring_alloc(100);
327 VSTRING *channel = vstring_alloc(100);
328 VSTRING *nexthop = vstring_alloc(100);
329 TRANSPORT_INFO *tp;
330 char *bp;
331 char *addr_field;
332 char *rcpt_domain;
333 char *expect_channel;
334 char *expect_nexthop;
335 int status;
336 int ch;
337 int errs = 0;
338
339 /*
340 * Parse JCL.
341 */
342 while ((ch = GETOPT(argc, argv, "v")) > 0) {
343 switch (ch) {
344 case 'v':
345 msg_verbose++;
346 break;
347 default:
348 usage(argv[0]);
349 }
350 }
351 if (argc != optind + 1)
352 usage(argv[0]);
353
354 /*
355 * Initialize.
356 */
357 #define UPDATE(var, val) do { myfree(var); var = mystrdup(val); } while (0)
358
359 mail_conf_read(); /* XXX eliminate dependency. */
360 UPDATE(var_rcpt_delim, "+");
361 UPDATE(var_mydomain, "localdomain");
362 UPDATE(var_myorigin, "localhost.localdomain");
363 UPDATE(var_mydest, "localhost.localdomain");
364
365 tp = transport_pre_init("transport map", argv[optind]);
366 transport_post_init(tp);
367
368 while (vstring_fgets_nonl(buffer, VSTREAM_IN)) {
369 bp = STR(buffer);
370
371 /*
372 * Parse the input and expectations. XXX We can't expect empty
373 * fields, so require '-' instead.
374 */
375 if ((addr_field = mystrtok(&bp, ":")) == 0)
376 msg_fatal("no address field");
377 if ((rcpt_domain = strrchr(addr_field, '@')) == 0)
378 msg_fatal("no recipient domain");
379 rcpt_domain += 1;
380 expect_channel = mystrtok(&bp, ":");
381 expect_nexthop = mystrtok(&bp, ":");
382 if ((expect_channel != 0) != (expect_nexthop != 0))
383 msg_fatal("specify both channel and nexthop, or specify neither");
384 if (expect_channel) {
385 if (strcmp(expect_channel, "-") == 0)
386 *expect_channel = 0;
387 if (strcmp(expect_nexthop, "-") == 0)
388 *expect_nexthop = 0;
389 vstring_strcpy(channel, "DEFAULT");
390 vstring_strcpy(nexthop, rcpt_domain);
391 }
392 if (mystrtok(&bp, ":") != 0)
393 msg_fatal("garbage after nexthop field");
394
395 /*
396 * Lookups.
397 */
398 status = transport_lookup(tp, addr_field, rcpt_domain,
399 channel, nexthop);
400
401 /*
402 * Enforce expectations.
403 */
404 if (expect_nexthop && status) {
405 vstream_printf("%s:%s -> %s:%s \n",
406 addr_field, rcpt_domain,
407 STR(channel), STR(nexthop));
408 vstream_fflush(VSTREAM_OUT);
409 if (strcmp(expect_channel, STR(channel)) != 0) {
410 msg_warn("expect channel '%s' but got '%s'",
411 expect_channel, STR(channel));
412 errs = 1;
413 }
414 if (strcmp(expect_nexthop, STR(nexthop)) != 0) {
415 msg_warn("expect nexthop '%s' but got '%s'",
416 expect_nexthop, STR(nexthop));
417 errs = 1;
418 }
419 } else if (expect_nexthop && !status) {
420 vstream_printf("%s:%s -> %s\n", addr_field, rcpt_domain,
421 tp->transport_path->error ?
422 "(try again)" : "(not found)");
423 vstream_fflush(VSTREAM_OUT);
424 msg_warn("expect channel '%s' but got none", expect_channel);
425 msg_warn("expect nexthop '%s' but got none", expect_nexthop);
426 errs = 1;
427 } else if (!status) {
428 vstream_printf("%s:%s -> %s\n", addr_field, rcpt_domain,
429 tp->transport_path->error ?
430 "(try again)" : "(not found)");
431 }
432 }
433 transport_free(tp);
434 vstring_free(nexthop);
435 vstring_free(channel);
436 vstring_free(buffer);
437 exit(errs != 0);
438 }
439
440 #endif
441