1 /*
2 * Network proxy abstraction in PuTTY
3 *
4 * A proxy layer, if necessary, wedges itself between the network
5 * code and the higher level backend.
6 */
7
8 #include <assert.h>
9 #include <ctype.h>
10 #include <string.h>
11
12 #include "putty.h"
13 #include "network.h"
14 #include "proxy.h"
15
16 #define do_proxy_dns(conf) \
17 (conf_get_int(conf, CONF_proxy_dns) == FORCE_ON || \
18 (conf_get_int(conf, CONF_proxy_dns) == AUTO && \
19 conf_get_int(conf, CONF_proxy_type) != PROXY_SOCKS4))
20
21 /*
22 * Call this when proxy negotiation is complete, so that this
23 * socket can begin working normally.
24 */
proxy_activate(ProxySocket * p)25 void proxy_activate (ProxySocket *p)
26 {
27 size_t output_before, output_after;
28
29 p->state = PROXY_STATE_ACTIVE;
30
31 /* we want to ignore new receive events until we have sent
32 * all of our buffered receive data.
33 */
34 sk_set_frozen(p->sub_socket, true);
35
36 /* how many bytes of output have we buffered? */
37 output_before = bufchain_size(&p->pending_oob_output_data) +
38 bufchain_size(&p->pending_output_data);
39 /* and keep track of how many bytes do not get sent. */
40 output_after = 0;
41
42 /* send buffered OOB writes */
43 while (bufchain_size(&p->pending_oob_output_data) > 0) {
44 ptrlen data = bufchain_prefix(&p->pending_oob_output_data);
45 output_after += sk_write_oob(p->sub_socket, data.ptr, data.len);
46 bufchain_consume(&p->pending_oob_output_data, data.len);
47 }
48
49 /* send buffered normal writes */
50 while (bufchain_size(&p->pending_output_data) > 0) {
51 ptrlen data = bufchain_prefix(&p->pending_output_data);
52 output_after += sk_write(p->sub_socket, data.ptr, data.len);
53 bufchain_consume(&p->pending_output_data, data.len);
54 }
55
56 /* if we managed to send any data, let the higher levels know. */
57 if (output_after < output_before)
58 plug_sent(p->plug, output_after);
59
60 /* if we have a pending EOF to send, send it */
61 if (p->pending_eof) sk_write_eof(p->sub_socket);
62
63 /* if the backend wanted the socket unfrozen, try to unfreeze.
64 * our set_frozen handler will flush buffered receive data before
65 * unfreezing the actual underlying socket.
66 */
67 if (!p->freeze)
68 sk_set_frozen(&p->sock, false);
69 }
70
71 /* basic proxy socket functions */
72
sk_proxy_plug(Socket * s,Plug * p)73 static Plug *sk_proxy_plug (Socket *s, Plug *p)
74 {
75 ProxySocket *ps = container_of(s, ProxySocket, sock);
76 Plug *ret = ps->plug;
77 if (p)
78 ps->plug = p;
79 return ret;
80 }
81
sk_proxy_close(Socket * s)82 static void sk_proxy_close (Socket *s)
83 {
84 ProxySocket *ps = container_of(s, ProxySocket, sock);
85
86 sk_close(ps->sub_socket);
87 sk_addr_free(ps->remote_addr);
88 sfree(ps);
89 }
90
sk_proxy_write(Socket * s,const void * data,size_t len)91 static size_t sk_proxy_write (Socket *s, const void *data, size_t len)
92 {
93 ProxySocket *ps = container_of(s, ProxySocket, sock);
94
95 if (ps->state != PROXY_STATE_ACTIVE) {
96 bufchain_add(&ps->pending_output_data, data, len);
97 return bufchain_size(&ps->pending_output_data);
98 }
99 return sk_write(ps->sub_socket, data, len);
100 }
101
sk_proxy_write_oob(Socket * s,const void * data,size_t len)102 static size_t sk_proxy_write_oob (Socket *s, const void *data, size_t len)
103 {
104 ProxySocket *ps = container_of(s, ProxySocket, sock);
105
106 if (ps->state != PROXY_STATE_ACTIVE) {
107 bufchain_clear(&ps->pending_output_data);
108 bufchain_clear(&ps->pending_oob_output_data);
109 bufchain_add(&ps->pending_oob_output_data, data, len);
110 return len;
111 }
112 return sk_write_oob(ps->sub_socket, data, len);
113 }
114
sk_proxy_write_eof(Socket * s)115 static void sk_proxy_write_eof (Socket *s)
116 {
117 ProxySocket *ps = container_of(s, ProxySocket, sock);
118
119 if (ps->state != PROXY_STATE_ACTIVE) {
120 ps->pending_eof = true;
121 return;
122 }
123 sk_write_eof(ps->sub_socket);
124 }
125
sk_proxy_set_frozen(Socket * s,bool is_frozen)126 static void sk_proxy_set_frozen (Socket *s, bool is_frozen)
127 {
128 ProxySocket *ps = container_of(s, ProxySocket, sock);
129
130 if (ps->state != PROXY_STATE_ACTIVE) {
131 ps->freeze = is_frozen;
132 return;
133 }
134
135 /* handle any remaining buffered recv data first */
136 if (bufchain_size(&ps->pending_input_data) > 0) {
137 ps->freeze = is_frozen;
138
139 /* loop while we still have buffered data, and while we are
140 * unfrozen. the plug_receive call in the loop could result
141 * in a call back into this function refreezing the socket,
142 * so we have to check each time.
143 */
144 while (!ps->freeze && bufchain_size(&ps->pending_input_data) > 0) {
145 char databuf[512];
146 ptrlen data = bufchain_prefix(&ps->pending_input_data);
147 if (data.len > lenof(databuf))
148 data.len = lenof(databuf);
149 memcpy(databuf, data.ptr, data.len);
150 bufchain_consume(&ps->pending_input_data, data.len);
151 plug_receive(ps->plug, 0, databuf, data.len);
152 }
153
154 /* if we're still frozen, we'll have to wait for another
155 * call from the backend to finish unbuffering the data.
156 */
157 if (ps->freeze) return;
158 }
159
160 sk_set_frozen(ps->sub_socket, is_frozen);
161 }
162
sk_proxy_socket_error(Socket * s)163 static const char * sk_proxy_socket_error (Socket *s)
164 {
165 ProxySocket *ps = container_of(s, ProxySocket, sock);
166 if (ps->error != NULL || ps->sub_socket == NULL) {
167 return ps->error;
168 }
169 return sk_socket_error(ps->sub_socket);
170 }
171
172 /* basic proxy plug functions */
173
plug_proxy_log(Plug * plug,PlugLogType type,SockAddr * addr,int port,const char * error_msg,int error_code)174 static void plug_proxy_log(Plug *plug, PlugLogType type, SockAddr *addr,
175 int port, const char *error_msg, int error_code)
176 {
177 ProxySocket *ps = container_of(plug, ProxySocket, plugimpl);
178
179 plug_log(ps->plug, type, addr, port, error_msg, error_code);
180 }
181
plug_proxy_closing(Plug * p,const char * error_msg,int error_code,bool calling_back)182 static void plug_proxy_closing (Plug *p, const char *error_msg,
183 int error_code, bool calling_back)
184 {
185 ProxySocket *ps = container_of(p, ProxySocket, plugimpl);
186
187 if (ps->state != PROXY_STATE_ACTIVE) {
188 ps->closing_error_msg = error_msg;
189 ps->closing_error_code = error_code;
190 ps->closing_calling_back = calling_back;
191 ps->negotiate(ps, PROXY_CHANGE_CLOSING);
192 } else {
193 plug_closing(ps->plug, error_msg, error_code, calling_back);
194 }
195 }
196
plug_proxy_receive(Plug * p,int urgent,const char * data,size_t len)197 static void plug_proxy_receive(
198 Plug *p, int urgent, const char *data, size_t len)
199 {
200 ProxySocket *ps = container_of(p, ProxySocket, plugimpl);
201
202 if (ps->state != PROXY_STATE_ACTIVE) {
203 /* we will lose the urgentness of this data, but since most,
204 * if not all, of this data will be consumed by the negotiation
205 * process, hopefully it won't affect the protocol above us
206 */
207 bufchain_add(&ps->pending_input_data, data, len);
208 ps->receive_urgent = (urgent != 0);
209 ps->receive_data = data;
210 ps->receive_len = len;
211 ps->negotiate(ps, PROXY_CHANGE_RECEIVE);
212 } else {
213 plug_receive(ps->plug, urgent, data, len);
214 }
215 }
216
plug_proxy_sent(Plug * p,size_t bufsize)217 static void plug_proxy_sent (Plug *p, size_t bufsize)
218 {
219 ProxySocket *ps = container_of(p, ProxySocket, plugimpl);
220
221 if (ps->state != PROXY_STATE_ACTIVE) {
222 ps->negotiate(ps, PROXY_CHANGE_SENT);
223 return;
224 }
225 plug_sent(ps->plug, bufsize);
226 }
227
plug_proxy_accepting(Plug * p,accept_fn_t constructor,accept_ctx_t ctx)228 static int plug_proxy_accepting(Plug *p,
229 accept_fn_t constructor, accept_ctx_t ctx)
230 {
231 ProxySocket *ps = container_of(p, ProxySocket, plugimpl);
232
233 if (ps->state != PROXY_STATE_ACTIVE) {
234 ps->accepting_constructor = constructor;
235 ps->accepting_ctx = ctx;
236 return ps->negotiate(ps, PROXY_CHANGE_ACCEPTING);
237 }
238 return plug_accepting(ps->plug, constructor, ctx);
239 }
240
241 /*
242 * This function can accept a NULL pointer as `addr', in which case
243 * it will only check the host name.
244 */
proxy_for_destination(SockAddr * addr,const char * hostname,int port,Conf * conf)245 static bool proxy_for_destination(SockAddr *addr, const char *hostname,
246 int port, Conf *conf)
247 {
248 int s = 0, e = 0;
249 char hostip[64];
250 int hostip_len, hostname_len;
251 const char *exclude_list;
252
253 /*
254 * Special local connections such as Unix-domain sockets
255 * unconditionally cannot be proxied, even in proxy-localhost
256 * mode. There just isn't any way to ask any known proxy type for
257 * them.
258 */
259 if (addr && sk_address_is_special_local(addr))
260 return false; /* do not proxy */
261
262 /*
263 * Check the host name and IP against the hard-coded
264 * representations of `localhost'.
265 */
266 if (!conf_get_bool(conf, CONF_even_proxy_localhost) &&
267 (sk_hostname_is_local(hostname) ||
268 (addr && sk_address_is_local(addr))))
269 return false; /* do not proxy */
270
271 /* we want a string representation of the IP address for comparisons */
272 if (addr) {
273 sk_getaddr(addr, hostip, 64);
274 hostip_len = strlen(hostip);
275 } else
276 hostip_len = 0; /* placate gcc; shouldn't be required */
277
278 hostname_len = strlen(hostname);
279
280 exclude_list = conf_get_str(conf, CONF_proxy_exclude_list);
281
282 /* now parse the exclude list, and see if either our IP
283 * or hostname matches anything in it.
284 */
285
286 while (exclude_list[s]) {
287 while (exclude_list[s] &&
288 (isspace((unsigned char)exclude_list[s]) ||
289 exclude_list[s] == ',')) s++;
290
291 if (!exclude_list[s]) break;
292
293 e = s;
294
295 while (exclude_list[e] &&
296 (isalnum((unsigned char)exclude_list[e]) ||
297 exclude_list[e] == '-' ||
298 exclude_list[e] == '.' ||
299 exclude_list[e] == '*')) e++;
300
301 if (exclude_list[s] == '*') {
302 /* wildcard at beginning of entry */
303
304 if ((addr && strnicmp(hostip + hostip_len - (e - s - 1),
305 exclude_list + s + 1, e - s - 1) == 0) ||
306 strnicmp(hostname + hostname_len - (e - s - 1),
307 exclude_list + s + 1, e - s - 1) == 0) {
308 /* IP/hostname range excluded. do not use proxy. */
309 return false;
310 }
311 } else if (exclude_list[e-1] == '*') {
312 /* wildcard at end of entry */
313
314 if ((addr && strnicmp(hostip, exclude_list + s, e - s - 1) == 0) ||
315 strnicmp(hostname, exclude_list + s, e - s - 1) == 0) {
316 /* IP/hostname range excluded. do not use proxy. */
317 return false;
318 }
319 } else {
320 /* no wildcard at either end, so let's try an absolute
321 * match (ie. a specific IP)
322 */
323
324 if (addr && strnicmp(hostip, exclude_list + s, e - s) == 0)
325 return false; /* IP/hostname excluded. do not use proxy. */
326 if (strnicmp(hostname, exclude_list + s, e - s) == 0)
327 return false; /* IP/hostname excluded. do not use proxy. */
328 }
329
330 s = e;
331
332 /* Make sure we really have reached the next comma or end-of-string */
333 while (exclude_list[s] &&
334 !isspace((unsigned char)exclude_list[s]) &&
335 exclude_list[s] != ',') s++;
336 }
337
338 /* no matches in the exclude list, so use the proxy */
339 return true;
340 }
341
dns_log_msg(const char * host,int addressfamily,const char * reason)342 static char *dns_log_msg(const char *host, int addressfamily,
343 const char *reason)
344 {
345 return dupprintf("Looking up host \"%s\"%s for %s", host,
346 (addressfamily == ADDRTYPE_IPV4 ? " (IPv4)" :
347 addressfamily == ADDRTYPE_IPV6 ? " (IPv6)" :
348 ""), reason);
349 }
350
name_lookup(const char * host,int port,char ** canonicalname,Conf * conf,int addressfamily,LogContext * logctx,const char * reason)351 SockAddr *name_lookup(const char *host, int port, char **canonicalname,
352 Conf *conf, int addressfamily, LogContext *logctx,
353 const char *reason)
354 {
355 if (conf_get_int(conf, CONF_proxy_type) != PROXY_NONE &&
356 do_proxy_dns(conf) &&
357 proxy_for_destination(NULL, host, port, conf)) {
358
359 if (logctx)
360 logeventf(logctx, "Leaving host lookup to proxy of \"%s\""
361 " (for %s)", host, reason);
362
363 *canonicalname = dupstr(host);
364 return sk_nonamelookup(host);
365 } else {
366 if (logctx)
367 logevent_and_free(
368 logctx, dns_log_msg(host, addressfamily, reason));
369
370 return sk_namelookup(host, canonicalname, addressfamily);
371 }
372 }
373
374 static const SocketVtable ProxySocket_sockvt = {
375 .plug = sk_proxy_plug,
376 .close = sk_proxy_close,
377 .write = sk_proxy_write,
378 .write_oob = sk_proxy_write_oob,
379 .write_eof = sk_proxy_write_eof,
380 .set_frozen = sk_proxy_set_frozen,
381 .socket_error = sk_proxy_socket_error,
382 .peer_info = NULL,
383 };
384
385 static const PlugVtable ProxySocket_plugvt = {
386 .log = plug_proxy_log,
387 .closing = plug_proxy_closing,
388 .receive = plug_proxy_receive,
389 .sent = plug_proxy_sent,
390 .accepting = plug_proxy_accepting
391 };
392
new_connection(SockAddr * addr,const char * hostname,int port,bool privport,bool oobinline,bool nodelay,bool keepalive,Plug * plug,Conf * conf)393 Socket *new_connection(SockAddr *addr, const char *hostname,
394 int port, bool privport,
395 bool oobinline, bool nodelay, bool keepalive,
396 Plug *plug, Conf *conf)
397 {
398 if (conf_get_int(conf, CONF_proxy_type) != PROXY_NONE &&
399 proxy_for_destination(addr, hostname, port, conf))
400 {
401 ProxySocket *ret;
402 SockAddr *proxy_addr;
403 char *proxy_canonical_name;
404 const char *proxy_type;
405 Socket *sret;
406 int type;
407
408 if ((sret = platform_new_connection(addr, hostname, port, privport,
409 oobinline, nodelay, keepalive,
410 plug, conf)) != NULL)
411 return sret;
412
413 ret = snew(ProxySocket);
414 ret->sock.vt = &ProxySocket_sockvt;
415 ret->plugimpl.vt = &ProxySocket_plugvt;
416 ret->conf = conf_copy(conf);
417 ret->plug = plug;
418 ret->remote_addr = addr; /* will need to be freed on close */
419 ret->remote_port = port;
420
421 ret->error = NULL;
422 ret->pending_eof = false;
423 ret->freeze = false;
424
425 bufchain_init(&ret->pending_input_data);
426 bufchain_init(&ret->pending_output_data);
427 bufchain_init(&ret->pending_oob_output_data);
428
429 ret->sub_socket = NULL;
430 ret->state = PROXY_STATE_NEW;
431 ret->negotiate = NULL;
432
433 type = conf_get_int(conf, CONF_proxy_type);
434 if (type == PROXY_HTTP) {
435 ret->negotiate = proxy_http_negotiate;
436 proxy_type = "HTTP";
437 } else if (type == PROXY_SOCKS4) {
438 ret->negotiate = proxy_socks4_negotiate;
439 proxy_type = "SOCKS 4";
440 } else if (type == PROXY_SOCKS5) {
441 ret->negotiate = proxy_socks5_negotiate;
442 proxy_type = "SOCKS 5";
443 } else if (type == PROXY_TELNET) {
444 ret->negotiate = proxy_telnet_negotiate;
445 proxy_type = "Telnet";
446 } else {
447 ret->error = "Proxy error: Unknown proxy method";
448 return &ret->sock;
449 }
450
451 {
452 char *logmsg = dupprintf("Will use %s proxy at %s:%d to connect"
453 " to %s:%d", proxy_type,
454 conf_get_str(conf, CONF_proxy_host),
455 conf_get_int(conf, CONF_proxy_port),
456 hostname, port);
457 plug_log(plug, PLUGLOG_PROXY_MSG, NULL, 0, logmsg, 0);
458 sfree(logmsg);
459 }
460
461 {
462 char *logmsg = dns_log_msg(conf_get_str(conf, CONF_proxy_host),
463 conf_get_int(conf, CONF_addressfamily),
464 "proxy");
465 plug_log(plug, PLUGLOG_PROXY_MSG, NULL, 0, logmsg, 0);
466 sfree(logmsg);
467 }
468
469 /* look-up proxy */
470 proxy_addr = sk_namelookup(conf_get_str(conf, CONF_proxy_host),
471 &proxy_canonical_name,
472 conf_get_int(conf, CONF_addressfamily));
473 if (sk_addr_error(proxy_addr) != NULL) {
474 ret->error = "Proxy error: Unable to resolve proxy host name";
475 sk_addr_free(proxy_addr);
476 return &ret->sock;
477 }
478 sfree(proxy_canonical_name);
479
480 {
481 char addrbuf[256], *logmsg;
482 sk_getaddr(proxy_addr, addrbuf, lenof(addrbuf));
483 logmsg = dupprintf("Connecting to %s proxy at %s port %d",
484 proxy_type, addrbuf,
485 conf_get_int(conf, CONF_proxy_port));
486 plug_log(plug, PLUGLOG_PROXY_MSG, NULL, 0, logmsg, 0);
487 sfree(logmsg);
488 }
489
490 /* create the actual socket we will be using,
491 * connected to our proxy server and port.
492 */
493 ret->sub_socket = sk_new(proxy_addr,
494 conf_get_int(conf, CONF_proxy_port),
495 privport, oobinline,
496 nodelay, keepalive, &ret->plugimpl);
497 if (sk_socket_error(ret->sub_socket) != NULL)
498 return &ret->sock;
499
500 /* start the proxy negotiation process... */
501 sk_set_frozen(ret->sub_socket, false);
502 ret->negotiate(ret, PROXY_CHANGE_NEW);
503
504 return &ret->sock;
505 }
506
507 /* no proxy, so just return the direct socket */
508 return sk_new(addr, port, privport, oobinline, nodelay, keepalive, plug);
509 }
510
new_listener(const char * srcaddr,int port,Plug * plug,bool local_host_only,Conf * conf,int addressfamily)511 Socket *new_listener(const char *srcaddr, int port, Plug *plug,
512 bool local_host_only, Conf *conf, int addressfamily)
513 {
514 /* TODO: SOCKS (and potentially others) support inbound
515 * TODO: connections via the proxy. support them.
516 */
517
518 return sk_newlistener(srcaddr, port, plug, local_host_only, addressfamily);
519 }
520
521 /* ----------------------------------------------------------------------
522 * HTTP CONNECT proxy type.
523 */
524
get_line_end(char * data,size_t len,size_t * out)525 static bool get_line_end(char *data, size_t len, size_t *out)
526 {
527 size_t off = 0;
528
529 while (off < len)
530 {
531 if (data[off] == '\n') {
532 /* we have a newline */
533 off++;
534
535 /* is that the only thing on this line? */
536 if (off <= 2) {
537 *out = off;
538 return true;
539 }
540
541 /* if not, then there is the possibility that this header
542 * continues onto the next line, if it starts with a space
543 * or a tab.
544 */
545
546 if (off + 1 < len && data[off+1] != ' ' && data[off+1] != '\t') {
547 *out = off;
548 return true;
549 }
550
551 /* the line does continue, so we have to keep going
552 * until we see an the header's "real" end of line.
553 */
554 off++;
555 }
556
557 off++;
558 }
559
560 return false;
561 }
562
proxy_http_negotiate(ProxySocket * p,int change)563 int proxy_http_negotiate (ProxySocket *p, int change)
564 {
565 if (p->state == PROXY_STATE_NEW) {
566 /* we are just beginning the proxy negotiate process,
567 * so we'll send off the initial bits of the request.
568 * for this proxy method, it's just a simple HTTP
569 * request
570 */
571 char *buf, dest[512];
572 char *username, *password;
573
574 sk_getaddr(p->remote_addr, dest, lenof(dest));
575
576 buf = dupprintf("CONNECT %s:%i HTTP/1.1\r\nHost: %s:%i\r\n",
577 dest, p->remote_port, dest, p->remote_port);
578 sk_write(p->sub_socket, buf, strlen(buf));
579 sfree(buf);
580
581 username = conf_get_str(p->conf, CONF_proxy_username);
582 password = conf_get_str(p->conf, CONF_proxy_password);
583 if (username[0] || password[0]) {
584 char *buf, *buf2;
585 int i, j, len;
586 buf = dupprintf("%s:%s", username, password);
587 len = strlen(buf);
588 buf2 = snewn(len * 4 / 3 + 100, char);
589 sprintf(buf2, "Proxy-Authorization: Basic ");
590 for (i = 0, j = strlen(buf2); i < len; i += 3, j += 4)
591 base64_encode_atom((unsigned char *)(buf+i),
592 (len-i > 3 ? 3 : len-i), buf2+j);
593 strcpy(buf2+j, "\r\n");
594 sk_write(p->sub_socket, buf2, strlen(buf2));
595 sfree(buf);
596 sfree(buf2);
597 }
598
599 sk_write(p->sub_socket, "\r\n", 2);
600
601 p->state = 1;
602 return 0;
603 }
604
605 if (change == PROXY_CHANGE_CLOSING) {
606 /* if our proxy negotiation process involves closing and opening
607 * new sockets, then we would want to intercept this closing
608 * callback when we were expecting it. if we aren't anticipating
609 * a socket close, then some error must have occurred. we'll
610 * just pass those errors up to the backend.
611 */
612 plug_closing(p->plug, p->closing_error_msg, p->closing_error_code,
613 p->closing_calling_back);
614 return 0; /* ignored */
615 }
616
617 if (change == PROXY_CHANGE_SENT) {
618 /* some (or all) of what we wrote to the proxy was sent.
619 * we don't do anything new, however, until we receive the
620 * proxy's response. we might want to set a timer so we can
621 * timeout the proxy negotiation after a while...
622 */
623 return 0;
624 }
625
626 if (change == PROXY_CHANGE_ACCEPTING) {
627 /* we should _never_ see this, as we are using our socket to
628 * connect to a proxy, not accepting inbound connections.
629 * what should we do? close the socket with an appropriate
630 * error message?
631 */
632 return plug_accepting(p->plug,
633 p->accepting_constructor, p->accepting_ctx);
634 }
635
636 if (change == PROXY_CHANGE_RECEIVE) {
637 /* we have received data from the underlying socket, which
638 * we'll need to parse, process, and respond to appropriately.
639 */
640
641 char *data, *datap;
642 size_t len, eol;
643
644 if (p->state == 1) {
645
646 int min_ver, maj_ver, status;
647
648 /* get the status line */
649 len = bufchain_size(&p->pending_input_data);
650 assert(len > 0); /* or we wouldn't be here */
651 data = snewn(len+1, char);
652 bufchain_fetch(&p->pending_input_data, data, len);
653 /*
654 * We must NUL-terminate this data, because Windows
655 * sscanf appears to require a NUL at the end of the
656 * string because it strlens it _first_. Sigh.
657 */
658 data[len] = '\0';
659
660 if (!get_line_end(data, len, &eol)) {
661 sfree(data);
662 return 1;
663 }
664
665 status = -1;
666 /* We can't rely on whether the %n incremented the sscanf return */
667 if (sscanf((char *)data, "HTTP/%i.%i %n",
668 &maj_ver, &min_ver, &status) < 2 || status == -1) {
669 plug_closing(p->plug, "Proxy error: HTTP response was absent",
670 PROXY_ERROR_GENERAL, 0);
671 sfree(data);
672 return 1;
673 }
674
675 /* remove the status line from the input buffer. */
676 bufchain_consume(&p->pending_input_data, eol);
677 if (data[status] != '2') {
678 /* error */
679 char *buf;
680 data[eol] = '\0';
681 while (eol > status &&
682 (data[eol-1] == '\r' || data[eol-1] == '\n'))
683 data[--eol] = '\0';
684 buf = dupprintf("Proxy error: %s", data+status);
685 plug_closing(p->plug, buf, PROXY_ERROR_GENERAL, 0);
686 sfree(buf);
687 sfree(data);
688 return 1;
689 }
690
691 sfree(data);
692
693 p->state = 2;
694 }
695
696 if (p->state == 2) {
697
698 /* get headers. we're done when we get a
699 * header of length 2, (ie. just "\r\n")
700 */
701
702 len = bufchain_size(&p->pending_input_data);
703 assert(len > 0); /* or we wouldn't be here */
704 data = snewn(len, char);
705 datap = data;
706 bufchain_fetch(&p->pending_input_data, data, len);
707
708 if (!get_line_end(datap, len, &eol)) {
709 sfree(data);
710 return 1;
711 }
712 while (eol > 2) {
713 bufchain_consume(&p->pending_input_data, eol);
714 datap += eol;
715 len -= eol;
716 if (!get_line_end(datap, len, &eol))
717 eol = 0; /* terminate the loop */
718 }
719
720 if (eol == 2) {
721 /* we're done */
722 bufchain_consume(&p->pending_input_data, 2);
723 proxy_activate(p);
724 /* proxy activate will have dealt with
725 * whatever is left of the buffer */
726 sfree(data);
727 return 1;
728 }
729
730 sfree(data);
731 return 1;
732 }
733 }
734
735 plug_closing(p->plug, "Proxy error: unexpected proxy error",
736 PROXY_ERROR_UNEXPECTED, 0);
737 return 1;
738 }
739
740 /* ----------------------------------------------------------------------
741 * SOCKS proxy type.
742 */
743
744 /* SOCKS version 4 */
proxy_socks4_negotiate(ProxySocket * p,int change)745 int proxy_socks4_negotiate (ProxySocket *p, int change)
746 {
747 if (p->state == PROXY_CHANGE_NEW) {
748
749 /* request format:
750 * version number (1 byte) = 4
751 * command code (1 byte)
752 * 1 = CONNECT
753 * 2 = BIND
754 * dest. port (2 bytes) [network order]
755 * dest. address (4 bytes)
756 * user ID (variable length, null terminated string)
757 */
758
759 strbuf *command = strbuf_new();
760 char hostname[512];
761 bool write_hostname = false;
762
763 put_byte(command, 4); /* SOCKS version 4 */
764 put_byte(command, 1); /* CONNECT command */
765 put_uint16(command, p->remote_port);
766
767 switch (sk_addrtype(p->remote_addr)) {
768 case ADDRTYPE_IPV4: {
769 char addr[4];
770 sk_addrcopy(p->remote_addr, addr);
771 put_data(command, addr, 4);
772 break;
773 }
774 case ADDRTYPE_NAME:
775 sk_getaddr(p->remote_addr, hostname, lenof(hostname));
776 put_uint32(command, 1);
777 write_hostname = true;
778 break;
779 case ADDRTYPE_IPV6:
780 p->error = "Proxy error: SOCKS version 4 does not support IPv6";
781 strbuf_free(command);
782 return 1;
783 }
784
785 put_asciz(command, conf_get_str(p->conf, CONF_proxy_username));
786 if (write_hostname)
787 put_asciz(command, hostname);
788 sk_write(p->sub_socket, command->s, command->len);
789 strbuf_free(command);
790
791 p->state = 1;
792 return 0;
793 }
794
795 if (change == PROXY_CHANGE_CLOSING) {
796 /* if our proxy negotiation process involves closing and opening
797 * new sockets, then we would want to intercept this closing
798 * callback when we were expecting it. if we aren't anticipating
799 * a socket close, then some error must have occurred. we'll
800 * just pass those errors up to the backend.
801 */
802 plug_closing(p->plug, p->closing_error_msg, p->closing_error_code,
803 p->closing_calling_back);
804 return 0; /* ignored */
805 }
806
807 if (change == PROXY_CHANGE_SENT) {
808 /* some (or all) of what we wrote to the proxy was sent.
809 * we don't do anything new, however, until we receive the
810 * proxy's response. we might want to set a timer so we can
811 * timeout the proxy negotiation after a while...
812 */
813 return 0;
814 }
815
816 if (change == PROXY_CHANGE_ACCEPTING) {
817 /* we should _never_ see this, as we are using our socket to
818 * connect to a proxy, not accepting inbound connections.
819 * what should we do? close the socket with an appropriate
820 * error message?
821 */
822 return plug_accepting(p->plug,
823 p->accepting_constructor, p->accepting_ctx);
824 }
825
826 if (change == PROXY_CHANGE_RECEIVE) {
827 /* we have received data from the underlying socket, which
828 * we'll need to parse, process, and respond to appropriately.
829 */
830
831 if (p->state == 1) {
832 /* response format:
833 * version number (1 byte) = 4
834 * reply code (1 byte)
835 * 90 = request granted
836 * 91 = request rejected or failed
837 * 92 = request rejected due to lack of IDENTD on client
838 * 93 = request rejected due to difference in user ID
839 * (what we sent vs. what IDENTD said)
840 * dest. port (2 bytes)
841 * dest. address (4 bytes)
842 */
843
844 char data[8];
845
846 if (bufchain_size(&p->pending_input_data) < 8)
847 return 1; /* not got anything yet */
848
849 /* get the response */
850 bufchain_fetch(&p->pending_input_data, data, 8);
851
852 if (data[0] != 0) {
853 plug_closing(p->plug, "Proxy error: SOCKS proxy responded with "
854 "unexpected reply code version",
855 PROXY_ERROR_GENERAL, 0);
856 return 1;
857 }
858
859 if (data[1] != 90) {
860
861 switch (data[1]) {
862 case 92:
863 plug_closing(p->plug, "Proxy error: SOCKS server wanted IDENTD on client",
864 PROXY_ERROR_GENERAL, 0);
865 break;
866 case 93:
867 plug_closing(p->plug, "Proxy error: Username and IDENTD on client don't agree",
868 PROXY_ERROR_GENERAL, 0);
869 break;
870 case 91:
871 default:
872 plug_closing(p->plug, "Proxy error: Error while communicating with proxy",
873 PROXY_ERROR_GENERAL, 0);
874 break;
875 }
876
877 return 1;
878 }
879 bufchain_consume(&p->pending_input_data, 8);
880
881 /* we're done */
882 proxy_activate(p);
883 /* proxy activate will have dealt with
884 * whatever is left of the buffer */
885 return 1;
886 }
887 }
888
889 plug_closing(p->plug, "Proxy error: unexpected proxy error",
890 PROXY_ERROR_UNEXPECTED, 0);
891 return 1;
892 }
893
894 /* SOCKS version 5 */
proxy_socks5_negotiate(ProxySocket * p,int change)895 int proxy_socks5_negotiate (ProxySocket *p, int change)
896 {
897 if (p->state == PROXY_CHANGE_NEW) {
898
899 /* initial command:
900 * version number (1 byte) = 5
901 * number of available authentication methods (1 byte)
902 * available authentication methods (1 byte * previous value)
903 * authentication methods:
904 * 0x00 = no authentication
905 * 0x01 = GSSAPI
906 * 0x02 = username/password
907 * 0x03 = CHAP
908 */
909
910 strbuf *command;
911 char *username, *password;
912 int method_count_offset, methods_start;
913
914 command = strbuf_new();
915 put_byte(command, 5); /* SOCKS version 5 */
916 username = conf_get_str(p->conf, CONF_proxy_username);
917 password = conf_get_str(p->conf, CONF_proxy_password);
918
919 method_count_offset = command->len;
920 put_byte(command, 0);
921 methods_start = command->len;
922
923 put_byte(command, 0x00); /* no authentication */
924
925 if (username[0] || password[0]) {
926 proxy_socks5_offerencryptedauth(BinarySink_UPCAST(command));
927 put_byte(command, 0x02); /* username/password */
928 }
929
930 command->u[method_count_offset] = command->len - methods_start;
931
932 sk_write(p->sub_socket, command->s, command->len);
933 strbuf_free(command);
934
935 p->state = 1;
936 return 0;
937 }
938
939 if (change == PROXY_CHANGE_CLOSING) {
940 /* if our proxy negotiation process involves closing and opening
941 * new sockets, then we would want to intercept this closing
942 * callback when we were expecting it. if we aren't anticipating
943 * a socket close, then some error must have occurred. we'll
944 * just pass those errors up to the backend.
945 */
946 plug_closing(p->plug, p->closing_error_msg, p->closing_error_code,
947 p->closing_calling_back);
948 return 0; /* ignored */
949 }
950
951 if (change == PROXY_CHANGE_SENT) {
952 /* some (or all) of what we wrote to the proxy was sent.
953 * we don't do anything new, however, until we receive the
954 * proxy's response. we might want to set a timer so we can
955 * timeout the proxy negotiation after a while...
956 */
957 return 0;
958 }
959
960 if (change == PROXY_CHANGE_ACCEPTING) {
961 /* we should _never_ see this, as we are using our socket to
962 * connect to a proxy, not accepting inbound connections.
963 * what should we do? close the socket with an appropriate
964 * error message?
965 */
966 return plug_accepting(p->plug,
967 p->accepting_constructor, p->accepting_ctx);
968 }
969
970 if (change == PROXY_CHANGE_RECEIVE) {
971 /* we have received data from the underlying socket, which
972 * we'll need to parse, process, and respond to appropriately.
973 */
974
975 if (p->state == 1) {
976
977 /* initial response:
978 * version number (1 byte) = 5
979 * authentication method (1 byte)
980 * authentication methods:
981 * 0x00 = no authentication
982 * 0x01 = GSSAPI
983 * 0x02 = username/password
984 * 0x03 = CHAP
985 * 0xff = no acceptable methods
986 */
987 char data[2];
988
989 if (bufchain_size(&p->pending_input_data) < 2)
990 return 1; /* not got anything yet */
991
992 /* get the response */
993 bufchain_fetch(&p->pending_input_data, data, 2);
994
995 if (data[0] != 5) {
996 plug_closing(p->plug, "Proxy error: SOCKS proxy returned unexpected version",
997 PROXY_ERROR_GENERAL, 0);
998 return 1;
999 }
1000
1001 if (data[1] == 0x00) p->state = 2; /* no authentication needed */
1002 else if (data[1] == 0x01) p->state = 4; /* GSSAPI authentication */
1003 else if (data[1] == 0x02) p->state = 5; /* username/password authentication */
1004 else if (data[1] == 0x03) p->state = 6; /* CHAP authentication */
1005 else {
1006 plug_closing(p->plug, "Proxy error: SOCKS proxy did not accept our authentication",
1007 PROXY_ERROR_GENERAL, 0);
1008 return 1;
1009 }
1010 bufchain_consume(&p->pending_input_data, 2);
1011 }
1012
1013 if (p->state == 7) {
1014
1015 /* password authentication reply format:
1016 * version number (1 bytes) = 1
1017 * reply code (1 byte)
1018 * 0 = succeeded
1019 * >0 = failed
1020 */
1021 char data[2];
1022
1023 if (bufchain_size(&p->pending_input_data) < 2)
1024 return 1; /* not got anything yet */
1025
1026 /* get the response */
1027 bufchain_fetch(&p->pending_input_data, data, 2);
1028
1029 if (data[0] != 1) {
1030 plug_closing(p->plug, "Proxy error: SOCKS password "
1031 "subnegotiation contained wrong version number",
1032 PROXY_ERROR_GENERAL, 0);
1033 return 1;
1034 }
1035
1036 if (data[1] != 0) {
1037
1038 plug_closing(p->plug, "Proxy error: SOCKS proxy refused"
1039 " password authentication",
1040 PROXY_ERROR_GENERAL, 0);
1041 return 1;
1042 }
1043
1044 bufchain_consume(&p->pending_input_data, 2);
1045 p->state = 2; /* now proceed as authenticated */
1046 }
1047
1048 if (p->state == 8) {
1049 int ret;
1050 ret = proxy_socks5_handlechap(p);
1051 if (ret) return ret;
1052 }
1053
1054 if (p->state == 2) {
1055
1056 /* request format:
1057 * version number (1 byte) = 5
1058 * command code (1 byte)
1059 * 1 = CONNECT
1060 * 2 = BIND
1061 * 3 = UDP ASSOCIATE
1062 * reserved (1 byte) = 0x00
1063 * address type (1 byte)
1064 * 1 = IPv4
1065 * 3 = domainname (first byte has length, no terminating null)
1066 * 4 = IPv6
1067 * dest. address (variable)
1068 * dest. port (2 bytes) [network order]
1069 */
1070
1071 strbuf *command = strbuf_new();
1072 put_byte(command, 5); /* SOCKS version 5 */
1073 put_byte(command, 1); /* CONNECT command */
1074 put_byte(command, 0x00); /* reserved byte */
1075
1076 switch (sk_addrtype(p->remote_addr)) {
1077 case ADDRTYPE_IPV4:
1078 put_byte(command, 1); /* IPv4 */
1079 sk_addrcopy(p->remote_addr, strbuf_append(command, 4));
1080 break;
1081 case ADDRTYPE_IPV6:
1082 put_byte(command, 4); /* IPv6 */
1083 sk_addrcopy(p->remote_addr, strbuf_append(command, 16));
1084 break;
1085 case ADDRTYPE_NAME: {
1086 char hostname[512];
1087 put_byte(command, 3); /* domain name */
1088 sk_getaddr(p->remote_addr, hostname, lenof(hostname));
1089 if (!put_pstring(command, hostname)) {
1090 p->error = "Proxy error: SOCKS 5 cannot "
1091 "support host names longer than 255 chars";
1092 strbuf_free(command);
1093 return 1;
1094 }
1095 break;
1096 }
1097 }
1098
1099 put_uint16(command, p->remote_port);
1100
1101 sk_write(p->sub_socket, command->s, command->len);
1102
1103 strbuf_free(command);
1104
1105 p->state = 3;
1106 return 1;
1107 }
1108
1109 if (p->state == 3) {
1110
1111 /* reply format:
1112 * version number (1 bytes) = 5
1113 * reply code (1 byte)
1114 * 0 = succeeded
1115 * 1 = general SOCKS server failure
1116 * 2 = connection not allowed by ruleset
1117 * 3 = network unreachable
1118 * 4 = host unreachable
1119 * 5 = connection refused
1120 * 6 = TTL expired
1121 * 7 = command not supported
1122 * 8 = address type not supported
1123 * reserved (1 byte) = x00
1124 * address type (1 byte)
1125 * 1 = IPv4
1126 * 3 = domainname (first byte has length, no terminating null)
1127 * 4 = IPv6
1128 * server bound address (variable)
1129 * server bound port (2 bytes) [network order]
1130 */
1131 char data[5];
1132 int len;
1133
1134 /* First 5 bytes of packet are enough to tell its length. */
1135 if (bufchain_size(&p->pending_input_data) < 5)
1136 return 1; /* not got anything yet */
1137
1138 /* get the response */
1139 bufchain_fetch(&p->pending_input_data, data, 5);
1140
1141 if (data[0] != 5) {
1142 plug_closing(p->plug, "Proxy error: SOCKS proxy returned wrong version number",
1143 PROXY_ERROR_GENERAL, 0);
1144 return 1;
1145 }
1146
1147 if (data[1] != 0) {
1148 char buf[256];
1149
1150 strcpy(buf, "Proxy error: ");
1151
1152 switch (data[1]) {
1153 case 1: strcat(buf, "General SOCKS server failure"); break;
1154 case 2: strcat(buf, "Connection not allowed by ruleset"); break;
1155 case 3: strcat(buf, "Network unreachable"); break;
1156 case 4: strcat(buf, "Host unreachable"); break;
1157 case 5: strcat(buf, "Connection refused"); break;
1158 case 6: strcat(buf, "TTL expired"); break;
1159 case 7: strcat(buf, "Command not supported"); break;
1160 case 8: strcat(buf, "Address type not supported"); break;
1161 default: sprintf(buf+strlen(buf),
1162 "Unrecognised SOCKS error code %d",
1163 data[1]);
1164 break;
1165 }
1166 plug_closing(p->plug, buf, PROXY_ERROR_GENERAL, 0);
1167
1168 return 1;
1169 }
1170
1171 /*
1172 * Eat the rest of the reply packet.
1173 */
1174 len = 6; /* first 4 bytes, last 2 */
1175 switch (data[3]) {
1176 case 1: len += 4; break; /* IPv4 address */
1177 case 4: len += 16; break;/* IPv6 address */
1178 case 3: len += 1+(unsigned char)data[4]; break; /* domain name */
1179 default:
1180 plug_closing(p->plug, "Proxy error: SOCKS proxy returned "
1181 "unrecognised address format",
1182 PROXY_ERROR_GENERAL, 0);
1183 return 1;
1184 }
1185 if (bufchain_size(&p->pending_input_data) < len)
1186 return 1; /* not got whole reply yet */
1187 bufchain_consume(&p->pending_input_data, len);
1188
1189 /* we're done */
1190 proxy_activate(p);
1191 return 1;
1192 }
1193
1194 if (p->state == 4) {
1195 /* TODO: Handle GSSAPI authentication */
1196 plug_closing(p->plug, "Proxy error: We don't support GSSAPI authentication",
1197 PROXY_ERROR_GENERAL, 0);
1198 return 1;
1199 }
1200
1201 if (p->state == 5) {
1202 const char *username = conf_get_str(p->conf, CONF_proxy_username);
1203 const char *password = conf_get_str(p->conf, CONF_proxy_password);
1204 if (username[0] || password[0]) {
1205 strbuf *auth = strbuf_new_nm();
1206 put_byte(auth, 1); /* version number of subnegotiation */
1207 if (!put_pstring(auth, username)) {
1208 p->error = "Proxy error: SOCKS 5 authentication cannot "
1209 "support usernames longer than 255 chars";
1210 strbuf_free(auth);
1211 return 1;
1212 }
1213 if (!put_pstring(auth, password)) {
1214 p->error = "Proxy error: SOCKS 5 authentication cannot "
1215 "support passwords longer than 255 chars";
1216 strbuf_free(auth);
1217 return 1;
1218 }
1219 sk_write(p->sub_socket, auth->s, auth->len);
1220 strbuf_free(auth);
1221 p->state = 7;
1222 } else
1223 plug_closing(p->plug, "Proxy error: Server chose "
1224 "username/password authentication but we "
1225 "didn't offer it!",
1226 PROXY_ERROR_GENERAL, 0);
1227 return 1;
1228 }
1229
1230 if (p->state == 6) {
1231 int ret;
1232 ret = proxy_socks5_selectchap(p);
1233 if (ret) return ret;
1234 }
1235
1236 }
1237
1238 plug_closing(p->plug, "Proxy error: Unexpected proxy error",
1239 PROXY_ERROR_UNEXPECTED, 0);
1240 return 1;
1241 }
1242
1243 /* ----------------------------------------------------------------------
1244 * `Telnet' proxy type.
1245 *
1246 * (This is for ad-hoc proxies where you connect to the proxy's
1247 * telnet port and send a command such as `connect host port'. The
1248 * command is configurable, since this proxy type is typically not
1249 * standardised or at all well-defined.)
1250 */
1251
format_telnet_command(SockAddr * addr,int port,Conf * conf)1252 char *format_telnet_command(SockAddr *addr, int port, Conf *conf)
1253 {
1254 char *fmt = conf_get_str(conf, CONF_proxy_telnet_command);
1255 int so = 0, eo = 0;
1256 strbuf *buf = strbuf_new();
1257
1258 /* we need to escape \\, \%, \r, \n, \t, \x??, \0???,
1259 * %%, %host, %port, %user, and %pass
1260 */
1261
1262 while (fmt[eo] != 0) {
1263
1264 /* scan forward until we hit end-of-line,
1265 * or an escape character (\ or %) */
1266 while (fmt[eo] != 0 && fmt[eo] != '%' && fmt[eo] != '\\')
1267 eo++;
1268
1269 /* if we hit eol, break out of our escaping loop */
1270 if (fmt[eo] == 0) break;
1271
1272 /* if there was any unescaped text before the escape
1273 * character, send that now */
1274 if (eo != so)
1275 put_data(buf, fmt + so, eo - so);
1276
1277 so = eo++;
1278
1279 /* if the escape character was the last character of
1280 * the line, we'll just stop and send it. */
1281 if (fmt[eo] == 0) break;
1282
1283 if (fmt[so] == '\\') {
1284
1285 /* we recognize \\, \%, \r, \n, \t, \x??.
1286 * anything else, we just send unescaped (including the \).
1287 */
1288
1289 switch (fmt[eo]) {
1290
1291 case '\\':
1292 put_byte(buf, '\\');
1293 eo++;
1294 break;
1295
1296 case '%':
1297 put_byte(buf, '%');
1298 eo++;
1299 break;
1300
1301 case 'r':
1302 put_byte(buf, '\r');
1303 eo++;
1304 break;
1305
1306 case 'n':
1307 put_byte(buf, '\n');
1308 eo++;
1309 break;
1310
1311 case 't':
1312 put_byte(buf, '\t');
1313 eo++;
1314 break;
1315
1316 case 'x':
1317 case 'X': {
1318 /* escaped hexadecimal value (ie. \xff) */
1319 unsigned char v = 0;
1320 int i = 0;
1321
1322 for (;;) {
1323 eo++;
1324 if (fmt[eo] >= '0' && fmt[eo] <= '9')
1325 v += fmt[eo] - '0';
1326 else if (fmt[eo] >= 'a' && fmt[eo] <= 'f')
1327 v += fmt[eo] - 'a' + 10;
1328 else if (fmt[eo] >= 'A' && fmt[eo] <= 'F')
1329 v += fmt[eo] - 'A' + 10;
1330 else {
1331 /* non hex character, so we abort and just
1332 * send the whole thing unescaped (including \x)
1333 */
1334 put_byte(buf, '\\');
1335 eo = so + 1;
1336 break;
1337 }
1338
1339 /* we only extract two hex characters */
1340 if (i == 1) {
1341 put_byte(buf, v);
1342 eo++;
1343 break;
1344 }
1345
1346 i++;
1347 v <<= 4;
1348 }
1349 break;
1350 }
1351
1352 default:
1353 put_data(buf, fmt + so, 2);
1354 eo++;
1355 break;
1356 }
1357 } else {
1358
1359 /* % escape. we recognize %%, %host, %port, %user, %pass.
1360 * %proxyhost, %proxyport. Anything else we just send
1361 * unescaped (including the %).
1362 */
1363
1364 if (fmt[eo] == '%') {
1365 put_byte(buf, '%');
1366 eo++;
1367 }
1368 else if (strnicmp(fmt + eo, "host", 4) == 0) {
1369 char dest[512];
1370 sk_getaddr(addr, dest, lenof(dest));
1371 put_data(buf, dest, strlen(dest));
1372 eo += 4;
1373 }
1374 else if (strnicmp(fmt + eo, "port", 4) == 0) {
1375 strbuf_catf(buf, "%d", port);
1376 eo += 4;
1377 }
1378 else if (strnicmp(fmt + eo, "user", 4) == 0) {
1379 const char *username = conf_get_str(conf, CONF_proxy_username);
1380 put_data(buf, username, strlen(username));
1381 eo += 4;
1382 }
1383 else if (strnicmp(fmt + eo, "pass", 4) == 0) {
1384 const char *password = conf_get_str(conf, CONF_proxy_password);
1385 put_data(buf, password, strlen(password));
1386 eo += 4;
1387 }
1388 else if (strnicmp(fmt + eo, "proxyhost", 9) == 0) {
1389 const char *host = conf_get_str(conf, CONF_proxy_host);
1390 put_data(buf, host, strlen(host));
1391 eo += 9;
1392 }
1393 else if (strnicmp(fmt + eo, "proxyport", 9) == 0) {
1394 int port = conf_get_int(conf, CONF_proxy_port);
1395 strbuf_catf(buf, "%d", port);
1396 eo += 9;
1397 }
1398 else {
1399 /* we don't escape this, so send the % now, and
1400 * don't advance eo, so that we'll consider the
1401 * text immediately following the % as unescaped.
1402 */
1403 put_byte(buf, '%');
1404 }
1405 }
1406
1407 /* resume scanning for additional escapes after this one. */
1408 so = eo;
1409 }
1410
1411 /* if there is any unescaped text at the end of the line, send it */
1412 if (eo != so) {
1413 put_data(buf, fmt + so, eo - so);
1414 }
1415
1416 return strbuf_to_str(buf);
1417 }
1418
proxy_telnet_negotiate(ProxySocket * p,int change)1419 int proxy_telnet_negotiate (ProxySocket *p, int change)
1420 {
1421 if (p->state == PROXY_CHANGE_NEW) {
1422 char *formatted_cmd;
1423
1424 formatted_cmd = format_telnet_command(p->remote_addr, p->remote_port,
1425 p->conf);
1426
1427 {
1428 /*
1429 * Re-escape control chars in the command, for logging.
1430 */
1431 char *reescaped = snewn(4*strlen(formatted_cmd) + 1, char);
1432 const char *in;
1433 char *out;
1434 char *logmsg;
1435
1436 for (in = formatted_cmd, out = reescaped; *in; in++) {
1437 if (*in == '\n') {
1438 *out++ = '\\'; *out++ = 'n';
1439 } else if (*in == '\r') {
1440 *out++ = '\\'; *out++ = 'r';
1441 } else if (*in == '\t') {
1442 *out++ = '\\'; *out++ = 't';
1443 } else if (*in == '\\') {
1444 *out++ = '\\'; *out++ = '\\';
1445 } else if ((unsigned)(((unsigned char)*in) - 0x20) <
1446 (0x7F-0x20)) {
1447 *out++ = *in;
1448 } else {
1449 out += sprintf(out, "\\x%02X", (unsigned)*in & 0xFF);
1450 }
1451 }
1452 *out = '\0';
1453
1454 logmsg = dupprintf("Sending Telnet proxy command: %s", reescaped);
1455 plug_log(p->plug, PLUGLOG_PROXY_MSG, NULL, 0, logmsg, 0);
1456 sfree(logmsg);
1457 sfree(reescaped);
1458 }
1459
1460 sk_write(p->sub_socket, formatted_cmd, strlen(formatted_cmd));
1461 sfree(formatted_cmd);
1462
1463 p->state = 1;
1464 return 0;
1465 }
1466
1467 if (change == PROXY_CHANGE_CLOSING) {
1468 /* if our proxy negotiation process involves closing and opening
1469 * new sockets, then we would want to intercept this closing
1470 * callback when we were expecting it. if we aren't anticipating
1471 * a socket close, then some error must have occurred. we'll
1472 * just pass those errors up to the backend.
1473 */
1474 plug_closing(p->plug, p->closing_error_msg, p->closing_error_code,
1475 p->closing_calling_back);
1476 return 0; /* ignored */
1477 }
1478
1479 if (change == PROXY_CHANGE_SENT) {
1480 /* some (or all) of what we wrote to the proxy was sent.
1481 * we don't do anything new, however, until we receive the
1482 * proxy's response. we might want to set a timer so we can
1483 * timeout the proxy negotiation after a while...
1484 */
1485 return 0;
1486 }
1487
1488 if (change == PROXY_CHANGE_ACCEPTING) {
1489 /* we should _never_ see this, as we are using our socket to
1490 * connect to a proxy, not accepting inbound connections.
1491 * what should we do? close the socket with an appropriate
1492 * error message?
1493 */
1494 return plug_accepting(p->plug,
1495 p->accepting_constructor, p->accepting_ctx);
1496 }
1497
1498 if (change == PROXY_CHANGE_RECEIVE) {
1499 /* we have received data from the underlying socket, which
1500 * we'll need to parse, process, and respond to appropriately.
1501 */
1502
1503 /* we're done */
1504 proxy_activate(p);
1505 /* proxy activate will have dealt with
1506 * whatever is left of the buffer */
1507 return 1;
1508 }
1509
1510 plug_closing(p->plug, "Proxy error: Unexpected proxy error",
1511 PROXY_ERROR_UNEXPECTED, 0);
1512 return 1;
1513 }
1514