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1 | /* $Cambridge: exim/src/src/smtp_out.c,v 1.1 2004/10/07 10:39:01 ph10 Exp $ */ |
2 | ||
3 | /************************************************* | |
4 | * Exim - an Internet mail transport agent * | |
5 | *************************************************/ | |
6 | ||
7 | /* Copyright (c) University of Cambridge 1995 - 2004 */ | |
8 | /* See the file NOTICE for conditions of use and distribution. */ | |
9 | ||
10 | /* A number of functions for driving outgoing SMTP calls. */ | |
11 | ||
12 | ||
13 | #include "exim.h" | |
14 | ||
15 | ||
16 | ||
17 | /************************************************* | |
18 | * Find an outgoing interface * | |
19 | *************************************************/ | |
20 | ||
21 | /* This function is called from the smtp transport and also from the callout | |
22 | code in verify.c. Its job is to expand a string to get a list of interfaces, | |
23 | and choose a suitable one (IPv4 or IPv6) for the outgoing address. | |
24 | ||
25 | Arguments: | |
26 | istring string interface setting, may be NULL, meaning "any", in | |
27 | which case the function does nothing | |
28 | host_af AF_INET or AF_INET6 for the outgoing IP address | |
29 | addr the mail address being handled (for setting errors) | |
30 | changed if not NULL, set TRUE if expansion actually changed istring | |
31 | interface point this to the interface | |
32 | msg to add to any error message | |
33 | ||
34 | Returns: TRUE on success, FALSE on failure, with error message | |
35 | set in addr and transport_return set to PANIC | |
36 | */ | |
37 | ||
38 | BOOL | |
39 | smtp_get_interface(uschar *istring, int host_af, address_item *addr, | |
40 | BOOL *changed, uschar **interface, uschar *msg) | |
41 | { | |
42 | uschar *expint; | |
43 | uschar *iface; | |
44 | int sep = 0; | |
45 | ||
46 | if (istring == NULL) return TRUE; | |
47 | ||
48 | expint = expand_string(istring); | |
49 | if (expint == NULL) | |
50 | { | |
51 | if (expand_string_forcedfail) return TRUE; | |
52 | addr->transport_return = PANIC; | |
53 | addr->message = string_sprintf("failed to expand \"interface\" " | |
54 | "option for %s: %s", msg, expand_string_message); | |
55 | return FALSE; | |
56 | } | |
57 | ||
58 | if (changed != NULL) *changed = expint != istring; | |
59 | ||
60 | while (isspace(*expint)) expint++; | |
61 | if (*expint == 0) return TRUE; | |
62 | ||
63 | while ((iface = string_nextinlist(&expint, &sep, big_buffer, | |
64 | big_buffer_size)) != NULL) | |
65 | { | |
66 | if (string_is_ip_address(iface, NULL) == 0) | |
67 | { | |
68 | addr->transport_return = PANIC; | |
69 | addr->message = string_sprintf("\"%s\" is not a valid IP " | |
70 | "address for the \"interface\" option for %s", | |
71 | iface, msg); | |
72 | return FALSE; | |
73 | } | |
74 | ||
75 | if (((Ustrchr(iface, ':') == NULL)? AF_INET:AF_INET6) == host_af) | |
76 | break; | |
77 | } | |
78 | ||
79 | if (iface != NULL) *interface = string_copy(iface); | |
80 | return TRUE; | |
81 | } | |
82 | ||
83 | ||
84 | ||
85 | /************************************************* | |
86 | * Find an outgoing port * | |
87 | *************************************************/ | |
88 | ||
89 | /* This function is called from the smtp transport and also from the callout | |
90 | code in verify.c. Its job is to find a port number. Note that getservbyname() | |
91 | produces the number in network byte order. | |
92 | ||
93 | Arguments: | |
94 | rstring raw (unexpanded) string representation of the port | |
95 | addr the mail address being handled (for setting errors) | |
96 | port stick the port in here | |
97 | msg for adding to error message | |
98 | ||
99 | Returns: TRUE on success, FALSE on failure, with error message set | |
100 | in addr, and transport_return set to PANIC | |
101 | */ | |
102 | ||
103 | BOOL | |
104 | smtp_get_port(uschar *rstring, address_item *addr, int *port, uschar *msg) | |
105 | { | |
106 | uschar *pstring = expand_string(rstring); | |
107 | ||
108 | if (pstring == NULL) | |
109 | { | |
110 | addr->transport_return = PANIC; | |
111 | addr->message = string_sprintf("failed to expand \"%s\" (\"port\" option) " | |
112 | "for %s: %s", rstring, msg, expand_string_message); | |
113 | return FALSE; | |
114 | } | |
115 | ||
116 | if (isdigit(*pstring)) | |
117 | { | |
118 | uschar *end; | |
119 | *port = Ustrtol(pstring, &end, 0); | |
120 | if (end != pstring + Ustrlen(pstring)) | |
121 | { | |
122 | addr->transport_return = PANIC; | |
123 | addr->message = string_sprintf("invalid port number for %s: %s", msg, | |
124 | pstring); | |
125 | return FALSE; | |
126 | } | |
127 | } | |
128 | ||
129 | else | |
130 | { | |
131 | struct servent *smtp_service = getservbyname(CS pstring, "tcp"); | |
132 | if (smtp_service == NULL) | |
133 | { | |
134 | addr->transport_return = PANIC; | |
135 | addr->message = string_sprintf("TCP port \"%s\" is not defined for %s", | |
136 | pstring, msg); | |
137 | return FALSE; | |
138 | } | |
139 | *port = ntohs(smtp_service->s_port); | |
140 | } | |
141 | ||
142 | return TRUE; | |
143 | } | |
144 | ||
145 | ||
146 | ||
147 | ||
148 | /************************************************* | |
149 | * Connect to remote host * | |
150 | *************************************************/ | |
151 | ||
152 | /* Create a socket, and connect it to a remote host. IPv6 addresses are | |
153 | detected by checking for a colon in the address. AF_INET6 is defined even on | |
154 | non-IPv6 systems, to enable the code to be less messy. However, on such systems | |
155 | host->address will always be an IPv4 address. | |
156 | ||
157 | The port field in the host item is used if it is set (usually router from SRV | |
158 | records). In other cases, the default passed as an argument is used. | |
159 | ||
160 | Arguments: | |
161 | host host item containing name and address (and sometimes port) | |
162 | host_af AF_INET or AF_INET6 | |
163 | port default, remote port to connect to, in host byte order for those | |
164 | hosts whose port setting is PORT_NONE | |
165 | interface outgoing interface address or NULL | |
166 | timeout timeout value or 0 | |
167 | keepalive TRUE to use keepalive | |
168 | ||
169 | Returns: connected socket number, or -1 with errno set | |
170 | */ | |
171 | ||
172 | int | |
173 | smtp_connect(host_item *host, int host_af, int port, uschar *interface, | |
174 | int timeout, BOOL keepalive) | |
175 | { | |
176 | int on = 1; | |
177 | int save_errno = 0; | |
178 | int sock; | |
179 | ||
180 | if (host->port != PORT_NONE) | |
181 | { | |
182 | HDEBUG(D_transport|D_acl|D_v) | |
183 | debug_printf("Transport port=%d replaced by host-specific port=%d\n", port, | |
184 | host->port); | |
185 | port = host->port; | |
186 | } | |
187 | ||
188 | HDEBUG(D_transport|D_acl|D_v) | |
189 | { | |
190 | if (interface == NULL) | |
191 | debug_printf("Connecting to %s [%s]:%d ... ",host->name,host->address,port); | |
192 | else | |
193 | debug_printf("Connecting to %s [%s]:%d from %s ... ", host->name, | |
194 | host->address, port, interface); | |
195 | } | |
196 | ||
197 | /* Create the socket */ | |
198 | ||
199 | if ((sock = ip_socket(SOCK_STREAM, host_af)) < 0) return -1; | |
200 | ||
201 | /* Set TCP_NODELAY; Exim does its own buffering. */ | |
202 | ||
203 | setsockopt(sock, IPPROTO_TCP, TCP_NODELAY, (uschar *)(&on), sizeof(on)); | |
204 | ||
205 | /* Bind to a specific interface if requested. Caller must ensure the interface | |
206 | is the same type (IPv4 or IPv6) as the outgoing address. */ | |
207 | ||
208 | if (interface != NULL && ip_bind(sock, host_af, interface, 0) < 0) | |
209 | { | |
210 | save_errno = errno; | |
211 | HDEBUG(D_transport|D_acl|D_v) | |
212 | debug_printf("unable to bind outgoing SMTP call to %s: %s", interface, | |
213 | strerror(errno)); | |
214 | } | |
215 | ||
216 | /* Connect to the remote host, and add keepalive to the socket before returning | |
217 | it, if requested. */ | |
218 | ||
219 | else if (ip_connect(sock, host_af, host->address, port, timeout) < 0) | |
220 | save_errno = errno; | |
221 | ||
222 | /* Either bind() or connect() failed */ | |
223 | ||
224 | if (save_errno != 0) | |
225 | { | |
226 | HDEBUG(D_transport|D_acl|D_v) debug_printf("failed\n"); | |
227 | close(sock); | |
228 | errno = save_errno; | |
229 | return -1; | |
230 | } | |
231 | ||
232 | /* Both bind() and connect() succeeded */ | |
233 | ||
234 | else | |
235 | { | |
236 | HDEBUG(D_transport|D_acl|D_v) debug_printf("connected\n"); | |
237 | if (keepalive) ip_keepalive(sock, host->address, TRUE); | |
238 | return sock; | |
239 | } | |
240 | } | |
241 | ||
242 | ||
243 | /************************************************* | |
244 | * Flush outgoing command buffer * | |
245 | *************************************************/ | |
246 | ||
247 | /* This function is called only from smtp_write_command() below. It flushes | |
248 | the buffer of outgoing commands. There is more than one in the buffer only when | |
249 | pipelining. | |
250 | ||
251 | Argument: | |
252 | outblock the SMTP output block | |
253 | ||
254 | Returns: TRUE if OK, FALSE on error, with errno set | |
255 | */ | |
256 | ||
257 | static BOOL | |
258 | flush_buffer(smtp_outblock *outblock) | |
259 | { | |
260 | int rc; | |
261 | ||
262 | #ifdef SUPPORT_TLS | |
263 | if (tls_active == outblock->sock) | |
264 | rc = tls_write(outblock->buffer, outblock->ptr - outblock->buffer); | |
265 | else | |
266 | #endif | |
267 | ||
268 | rc = send(outblock->sock, outblock->buffer, outblock->ptr - outblock->buffer, 0); | |
269 | if (rc <= 0) | |
270 | { | |
271 | HDEBUG(D_transport|D_acl) debug_printf("send failed: %s\n", strerror(errno)); | |
272 | return FALSE; | |
273 | } | |
274 | ||
275 | outblock->ptr = outblock->buffer; | |
276 | outblock->cmd_count = 0; | |
277 | return TRUE; | |
278 | } | |
279 | ||
280 | ||
281 | ||
282 | /************************************************* | |
283 | * Write SMTP command * | |
284 | *************************************************/ | |
285 | ||
286 | /* The formatted command is left in big_buffer so that it can be reflected in | |
287 | any error message. | |
288 | ||
289 | Arguments: | |
290 | outblock contains buffer for pipelining, and socket | |
291 | noflush if TRUE, save the command in the output buffer, for pipelining | |
292 | format a format, starting with one of | |
293 | of HELO, MAIL FROM, RCPT TO, DATA, ".", or QUIT. | |
294 | ... data for the format | |
295 | ||
296 | Returns: 0 if command added to pipelining buffer, with nothing transmitted | |
297 | +n if n commands transmitted (may still have buffered the new one) | |
298 | -1 on error, with errno set | |
299 | */ | |
300 | ||
301 | int | |
302 | smtp_write_command(smtp_outblock *outblock, BOOL noflush, char *format, ...) | |
303 | { | |
304 | int count; | |
305 | int rc = 0; | |
306 | va_list ap; | |
307 | ||
308 | va_start(ap, format); | |
309 | if (!string_vformat(big_buffer, big_buffer_size, CS format, ap)) | |
310 | log_write(0, LOG_MAIN|LOG_PANIC_DIE, "overlong write_command in outgoing " | |
311 | "SMTP"); | |
312 | va_end(ap); | |
313 | count = Ustrlen(big_buffer); | |
314 | ||
315 | if (count > outblock->buffersize - (outblock->ptr - outblock->buffer)) | |
316 | { | |
317 | rc = outblock->cmd_count; /* flush resets */ | |
318 | if (!flush_buffer(outblock)) return -1; | |
319 | } | |
320 | ||
321 | Ustrncpy(CS outblock->ptr, big_buffer, count); | |
322 | outblock->ptr += count; | |
323 | outblock->cmd_count++; | |
324 | count -= 2; | |
325 | big_buffer[count] = 0; /* remove \r\n for error message */ | |
326 | ||
327 | /* We want to hide the actual data sent in AUTH transactions from reflections | |
328 | and logs. While authenticating, a flag is set in the outblock to enable this. | |
329 | The AUTH command itself gets any data flattened. Other lines are flattened | |
330 | completely. */ | |
331 | ||
332 | if (outblock->authenticating) | |
333 | { | |
334 | uschar *p = big_buffer; | |
335 | if (Ustrncmp(big_buffer, "AUTH ", 5) == 0) | |
336 | { | |
337 | p += 5; | |
338 | while (isspace(*p)) p++; | |
339 | while (!isspace(*p)) p++; | |
340 | while (isspace(*p)) p++; | |
341 | } | |
342 | while (*p != 0) *p++ = '*'; | |
343 | } | |
344 | ||
345 | HDEBUG(D_transport|D_acl|D_v) debug_printf(" SMTP>> %s\n", big_buffer); | |
346 | ||
347 | if (!noflush) | |
348 | { | |
349 | rc += outblock->cmd_count; /* flush resets */ | |
350 | if (!flush_buffer(outblock)) return -1; | |
351 | } | |
352 | ||
353 | return rc; | |
354 | } | |
355 | ||
356 | ||
357 | ||
358 | /************************************************* | |
359 | * Read one line of SMTP response * | |
360 | *************************************************/ | |
361 | ||
362 | /* This function reads one line of SMTP response from the server host. This may | |
363 | not be a complete response - it could be just part of a multiline response. We | |
364 | have to use a buffer for incoming packets, because when pipelining or using | |
365 | LMTP, there may well be more than one response in a single packet. This | |
366 | function is called only from the one that follows. | |
367 | ||
368 | Arguments: | |
369 | inblock the SMTP input block (contains holding buffer, socket, etc.) | |
370 | buffer where to put the line | |
371 | size space available for the line | |
372 | timeout the timeout to use when reading a packet | |
373 | ||
374 | Returns: length of a line that has been put in the buffer | |
375 | -1 otherwise, with errno set | |
376 | */ | |
377 | ||
378 | static int | |
379 | read_response_line(smtp_inblock *inblock, uschar *buffer, int size, int timeout) | |
380 | { | |
381 | uschar *p = buffer; | |
382 | uschar *ptr = inblock->ptr; | |
383 | uschar *ptrend = inblock->ptrend; | |
384 | int sock = inblock->sock; | |
385 | ||
386 | /* Loop for reading multiple packets or reading another packet after emptying | |
387 | a previously-read one. */ | |
388 | ||
389 | for (;;) | |
390 | { | |
391 | int rc; | |
392 | ||
393 | /* If there is data in the input buffer left over from last time, copy | |
394 | characters from it until the end of a line, at which point we can return, | |
395 | having removed any whitespace (which will include CR) at the end of the line. | |
396 | The rules for SMTP say that lines end in CRLF, but there are have been cases | |
397 | of hosts using just LF, and other MTAs are reported to handle this, so we | |
398 | just look for LF. If we run out of characters before the end of a line, | |
399 | carry on to read the next incoming packet. */ | |
400 | ||
401 | while (ptr < ptrend) | |
402 | { | |
403 | int c = *ptr++; | |
404 | if (c == '\n') | |
405 | { | |
406 | while (p > buffer && isspace(p[-1])) p--; | |
407 | *p = 0; | |
408 | inblock->ptr = ptr; | |
409 | return p - buffer; | |
410 | } | |
411 | *p++ = c; | |
412 | if (--size < 4) | |
413 | { | |
414 | *p = 0; /* Leave malformed line for error message */ | |
415 | errno = ERRNO_SMTPFORMAT; | |
416 | return -1; | |
417 | } | |
418 | } | |
419 | ||
420 | /* Need to read a new input packet. */ | |
421 | ||
422 | rc = ip_recv(sock, inblock->buffer, inblock->buffersize, timeout); | |
423 | if (rc <= 0) break; | |
424 | ||
425 | /* Another block of data has been successfully read. Set up the pointers | |
426 | and let the loop continue. */ | |
427 | ||
428 | ptrend = inblock->ptrend = inblock->buffer + rc; | |
429 | ptr = inblock->buffer; | |
430 | DEBUG(D_transport|D_acl) debug_printf("read response data: size=%d\n", rc); | |
431 | } | |
432 | ||
433 | /* Get here if there has been some kind of recv() error; errno is set, but we | |
434 | ensure that the result buffer is empty before returning. */ | |
435 | ||
436 | *buffer = 0; | |
437 | return -1; | |
438 | } | |
439 | ||
440 | ||
441 | ||
442 | ||
443 | ||
444 | /************************************************* | |
445 | * Read SMTP response * | |
446 | *************************************************/ | |
447 | ||
448 | /* This function reads an SMTP response with a timeout, and returns the | |
449 | response in the given buffer, as a string. A multiline response will contain | |
450 | newline characters between the lines. The function also analyzes the first | |
451 | digit of the reply code and returns FALSE if it is not acceptable. FALSE is | |
452 | also returned after a reading error. In this case buffer[0] will be zero, and | |
453 | the error code will be in errno. | |
454 | ||
455 | Arguments: | |
456 | inblock the SMTP input block (contains holding buffer, socket, etc.) | |
457 | buffer where to put the response | |
458 | size the size of the buffer | |
459 | okdigit the expected first digit of the response | |
460 | timeout the timeout to use | |
461 | ||
462 | Returns: TRUE if a valid, non-error response was received; else FALSE | |
463 | */ | |
464 | ||
465 | BOOL | |
466 | smtp_read_response(smtp_inblock *inblock, uschar *buffer, int size, int okdigit, | |
467 | int timeout) | |
468 | { | |
469 | uschar *ptr = buffer; | |
470 | int count; | |
471 | ||
472 | errno = 0; /* Ensure errno starts out zero */ | |
473 | ||
474 | /* This is a loop to read and concatentate the lines that make up a multi-line | |
475 | response. */ | |
476 | ||
477 | for (;;) | |
478 | { | |
479 | if ((count = read_response_line(inblock, ptr, size, timeout)) < 0) | |
480 | return FALSE; | |
481 | ||
482 | HDEBUG(D_transport|D_acl|D_v) | |
483 | debug_printf(" %s %s\n", (ptr == buffer)? "SMTP<<" : " ", ptr); | |
484 | ||
485 | /* Check the format of the response: it must start with three digits; if | |
486 | these are followed by a space or end of line, the response is complete. If | |
487 | they are followed by '-' this is a multi-line response and we must look for | |
488 | another line until the final line is reached. The only use made of multi-line | |
489 | responses is to pass them back as error messages. We therefore just | |
490 | concatenate them all within the buffer, which should be large enough to | |
491 | accept any reasonable number of lines. */ | |
492 | ||
493 | if (count < 3 || | |
494 | !isdigit(ptr[0]) || | |
495 | !isdigit(ptr[1]) || | |
496 | !isdigit(ptr[2]) || | |
497 | (ptr[3] != '-' && ptr[3] != ' ' && ptr[3] != 0)) | |
498 | { | |
499 | errno = ERRNO_SMTPFORMAT; /* format error */ | |
500 | return FALSE; | |
501 | } | |
502 | ||
503 | /* If the line we have just read is a terminal line, line, we are done. | |
504 | Otherwise more data has to be read. */ | |
505 | ||
506 | if (ptr[3] != '-') break; | |
507 | ||
508 | /* Move the reading pointer upwards in the buffer and insert \n between the | |
509 | components of a multiline response. Space is left for this by read_response_ | |
510 | line(). */ | |
511 | ||
512 | ptr += count; | |
513 | *ptr++ = '\n'; | |
514 | size -= count + 1; | |
515 | } | |
516 | ||
517 | /* Return a value that depends on the SMTP return code. On some systems a | |
518 | non-zero value of errno has been seen at this point, so ensure it is zero, | |
519 | because the caller of this function looks at errno when FALSE is returned, to | |
520 | distinguish between an unexpected return code and other errors such as | |
521 | timeouts, lost connections, etc. */ | |
522 | ||
523 | errno = 0; | |
524 | return buffer[0] == okdigit; | |
525 | } | |
526 | ||
527 | /* End of smtp_out.c */ |