Logging: fix DKIM precis received log line element.
[exim.git] / src / src / smtp_in.c
1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
4
5 /* Copyright (c) University of Cambridge 1995 - 2018 */
6 /* See the file NOTICE for conditions of use and distribution. */
7
8 /* Functions for handling an incoming SMTP call. */
9
10
11 #include "exim.h"
12 #include <assert.h>
13
14
15 /* Initialize for TCP wrappers if so configured. It appears that the macro
16 HAVE_IPV6 is used in some versions of the tcpd.h header, so we unset it before
17 including that header, and restore its value afterwards. */
18
19 #ifdef USE_TCP_WRAPPERS
20
21 #if HAVE_IPV6
22 #define EXIM_HAVE_IPV6
23 #endif
24 #undef HAVE_IPV6
25 #include <tcpd.h>
26 #undef HAVE_IPV6
27 #ifdef EXIM_HAVE_IPV6
28 #define HAVE_IPV6 TRUE
29 #endif
30
31 int allow_severity = LOG_INFO;
32 int deny_severity = LOG_NOTICE;
33 uschar *tcp_wrappers_name;
34 #endif
35
36
37 /* Size of buffer for reading SMTP commands. We used to use 512, as defined
38 by RFC 821. However, RFC 1869 specifies that this must be increased for SMTP
39 commands that accept arguments, and this in particular applies to AUTH, where
40 the data can be quite long. More recently this value was 2048 in Exim;
41 however, RFC 4954 (circa 2007) recommends 12288 bytes to handle AUTH. Clients
42 such as Thunderbird will send an AUTH with an initial-response for GSSAPI.
43 The maximum size of a Kerberos ticket under Windows 2003 is 12000 bytes, and
44 we need room to handle large base64-encoded AUTHs for GSSAPI.
45 */
46
47 #define SMTP_CMD_BUFFER_SIZE 16384
48
49 /* Size of buffer for reading SMTP incoming packets */
50
51 #define IN_BUFFER_SIZE 8192
52
53 /* Structure for SMTP command list */
54
55 typedef struct {
56 const char *name;
57 int len;
58 short int cmd;
59 short int has_arg;
60 short int is_mail_cmd;
61 } smtp_cmd_list;
62
63 /* Codes for identifying commands. We order them so that those that come first
64 are those for which synchronization is always required. Checking this can help
65 block some spam. */
66
67 enum {
68 /* These commands are required to be synchronized, i.e. to be the last in a
69 block of commands when pipelining. */
70
71 HELO_CMD, EHLO_CMD, DATA_CMD, /* These are listed in the pipelining */
72 VRFY_CMD, EXPN_CMD, NOOP_CMD, /* RFC as requiring synchronization */
73 ETRN_CMD, /* This by analogy with TURN from the RFC */
74 STARTTLS_CMD, /* Required by the STARTTLS RFC */
75 TLS_AUTH_CMD, /* auto-command at start of SSL */
76
77 /* This is a dummy to identify the non-sync commands when pipelining */
78
79 NON_SYNC_CMD_PIPELINING,
80
81 /* These commands need not be synchronized when pipelining */
82
83 MAIL_CMD, RCPT_CMD, RSET_CMD,
84
85 /* This is a dummy to identify the non-sync commands when not pipelining */
86
87 NON_SYNC_CMD_NON_PIPELINING,
88
89 /* RFC3030 section 2: "After all MAIL and RCPT responses are collected and
90 processed the message is sent using a series of BDAT commands"
91 implies that BDAT should be synchronized. However, we see Google, at least,
92 sending MAIL,RCPT,BDAT-LAST in a single packet, clearly not waiting for
93 processing of the RCPT response(s). We shall do the same, and not require
94 synch for BDAT. Worse, as the chunk may (very likely will) follow the
95 command-header in the same packet we cannot do the usual "is there any
96 follow-on data after the command line" even for non-pipeline mode.
97 So we'll need an explicit check after reading the expected chunk amount
98 when non-pipe, before sending the ACK. */
99
100 BDAT_CMD,
101
102 /* I have been unable to find a statement about the use of pipelining
103 with AUTH, so to be on the safe side it is here, though I kind of feel
104 it should be up there with the synchronized commands. */
105
106 AUTH_CMD,
107
108 /* I'm not sure about these, but I don't think they matter. */
109
110 QUIT_CMD, HELP_CMD,
111
112 #ifdef SUPPORT_PROXY
113 PROXY_FAIL_IGNORE_CMD,
114 #endif
115
116 /* These are specials that don't correspond to actual commands */
117
118 EOF_CMD, OTHER_CMD, BADARG_CMD, BADCHAR_CMD, BADSYN_CMD,
119 TOO_MANY_NONMAIL_CMD };
120
121
122 /* This is a convenience macro for adding the identity of an SMTP command
123 to the circular buffer that holds a list of the last n received. */
124
125 #define HAD(n) \
126 smtp_connection_had[smtp_ch_index++] = n; \
127 if (smtp_ch_index >= SMTP_HBUFF_SIZE) smtp_ch_index = 0
128
129
130 /*************************************************
131 * Local static variables *
132 *************************************************/
133
134 static auth_instance *authenticated_by;
135 static BOOL auth_advertised;
136 #ifdef SUPPORT_TLS
137 static BOOL tls_advertised;
138 #endif
139 static BOOL dsn_advertised;
140 static BOOL esmtp;
141 static BOOL helo_required = FALSE;
142 static BOOL helo_verify = FALSE;
143 static BOOL helo_seen;
144 static BOOL helo_accept_junk;
145 static BOOL count_nonmail;
146 static BOOL pipelining_advertised;
147 static BOOL rcpt_smtp_response_same;
148 static BOOL rcpt_in_progress;
149 static int nonmail_command_count;
150 static BOOL smtp_exit_function_called = 0;
151 #ifdef SUPPORT_I18N
152 static BOOL smtputf8_advertised;
153 #endif
154 static int synprot_error_count;
155 static int unknown_command_count;
156 static int sync_cmd_limit;
157 static int smtp_write_error = 0;
158
159 static uschar *rcpt_smtp_response;
160 static uschar *smtp_data_buffer;
161 static uschar *smtp_cmd_data;
162
163 /* We need to know the position of RSET, HELO, EHLO, AUTH, and STARTTLS. Their
164 final fields of all except AUTH are forced TRUE at the start of a new message
165 setup, to allow one of each between messages that is not counted as a nonmail
166 command. (In fact, only one of HELO/EHLO is not counted.) Also, we have to
167 allow a new EHLO after starting up TLS.
168
169 AUTH is "falsely" labelled as a mail command initially, so that it doesn't get
170 counted. However, the flag is changed when AUTH is received, so that multiple
171 failing AUTHs will eventually hit the limit. After a successful AUTH, another
172 AUTH is already forbidden. After a TLS session is started, AUTH's flag is again
173 forced TRUE, to allow for the re-authentication that can happen at that point.
174
175 QUIT is also "falsely" labelled as a mail command so that it doesn't up the
176 count of non-mail commands and possibly provoke an error.
177
178 tls_auth is a pseudo-command, never expected in input. It is activated
179 on TLS startup and looks for a tls authenticator. */
180
181 static smtp_cmd_list cmd_list[] = {
182 /* name len cmd has_arg is_mail_cmd */
183
184 { "rset", sizeof("rset")-1, RSET_CMD, FALSE, FALSE }, /* First */
185 { "helo", sizeof("helo")-1, HELO_CMD, TRUE, FALSE },
186 { "ehlo", sizeof("ehlo")-1, EHLO_CMD, TRUE, FALSE },
187 { "auth", sizeof("auth")-1, AUTH_CMD, TRUE, TRUE },
188 #ifdef SUPPORT_TLS
189 { "starttls", sizeof("starttls")-1, STARTTLS_CMD, FALSE, FALSE },
190 { "tls_auth", 0, TLS_AUTH_CMD, FALSE, FALSE },
191 #endif
192
193 /* If you change anything above here, also fix the definitions below. */
194
195 { "mail from:", sizeof("mail from:")-1, MAIL_CMD, TRUE, TRUE },
196 { "rcpt to:", sizeof("rcpt to:")-1, RCPT_CMD, TRUE, TRUE },
197 { "data", sizeof("data")-1, DATA_CMD, FALSE, TRUE },
198 { "bdat", sizeof("bdat")-1, BDAT_CMD, TRUE, TRUE },
199 { "quit", sizeof("quit")-1, QUIT_CMD, FALSE, TRUE },
200 { "noop", sizeof("noop")-1, NOOP_CMD, TRUE, FALSE },
201 { "etrn", sizeof("etrn")-1, ETRN_CMD, TRUE, FALSE },
202 { "vrfy", sizeof("vrfy")-1, VRFY_CMD, TRUE, FALSE },
203 { "expn", sizeof("expn")-1, EXPN_CMD, TRUE, FALSE },
204 { "help", sizeof("help")-1, HELP_CMD, TRUE, FALSE }
205 };
206
207 static smtp_cmd_list *cmd_list_end =
208 cmd_list + sizeof(cmd_list)/sizeof(smtp_cmd_list);
209
210 #define CMD_LIST_RSET 0
211 #define CMD_LIST_HELO 1
212 #define CMD_LIST_EHLO 2
213 #define CMD_LIST_AUTH 3
214 #define CMD_LIST_STARTTLS 4
215 #define CMD_LIST_TLS_AUTH 5
216
217 /* This list of names is used for performing the smtp_no_mail logging action.
218 It must be kept in step with the SCH_xxx enumerations. */
219
220 static uschar *smtp_names[] =
221 {
222 US"NONE", US"AUTH", US"DATA", US"BDAT", US"EHLO", US"ETRN", US"EXPN",
223 US"HELO", US"HELP", US"MAIL", US"NOOP", US"QUIT", US"RCPT", US"RSET",
224 US"STARTTLS", US"VRFY" };
225
226 static uschar *protocols_local[] = {
227 US"local-smtp", /* HELO */
228 US"local-smtps", /* The rare case EHLO->STARTTLS->HELO */
229 US"local-esmtp", /* EHLO */
230 US"local-esmtps", /* EHLO->STARTTLS->EHLO */
231 US"local-esmtpa", /* EHLO->AUTH */
232 US"local-esmtpsa" /* EHLO->STARTTLS->EHLO->AUTH */
233 };
234 static uschar *protocols[] = {
235 US"smtp", /* HELO */
236 US"smtps", /* The rare case EHLO->STARTTLS->HELO */
237 US"esmtp", /* EHLO */
238 US"esmtps", /* EHLO->STARTTLS->EHLO */
239 US"esmtpa", /* EHLO->AUTH */
240 US"esmtpsa" /* EHLO->STARTTLS->EHLO->AUTH */
241 };
242
243 #define pnormal 0
244 #define pextend 2
245 #define pcrpted 1 /* added to pextend or pnormal */
246 #define pauthed 2 /* added to pextend */
247
248 /* Sanity check and validate optional args to MAIL FROM: envelope */
249 enum {
250 ENV_MAIL_OPT_NULL,
251 ENV_MAIL_OPT_SIZE, ENV_MAIL_OPT_BODY, ENV_MAIL_OPT_AUTH,
252 #ifndef DISABLE_PRDR
253 ENV_MAIL_OPT_PRDR,
254 #endif
255 ENV_MAIL_OPT_RET, ENV_MAIL_OPT_ENVID,
256 #ifdef SUPPORT_I18N
257 ENV_MAIL_OPT_UTF8,
258 #endif
259 };
260 typedef struct {
261 uschar * name; /* option requested during MAIL cmd */
262 int value; /* enum type */
263 BOOL need_value; /* TRUE requires value (name=value pair format)
264 FALSE is a singleton */
265 } env_mail_type_t;
266 static env_mail_type_t env_mail_type_list[] = {
267 { US"SIZE", ENV_MAIL_OPT_SIZE, TRUE },
268 { US"BODY", ENV_MAIL_OPT_BODY, TRUE },
269 { US"AUTH", ENV_MAIL_OPT_AUTH, TRUE },
270 #ifndef DISABLE_PRDR
271 { US"PRDR", ENV_MAIL_OPT_PRDR, FALSE },
272 #endif
273 { US"RET", ENV_MAIL_OPT_RET, TRUE },
274 { US"ENVID", ENV_MAIL_OPT_ENVID, TRUE },
275 #ifdef SUPPORT_I18N
276 { US"SMTPUTF8",ENV_MAIL_OPT_UTF8, FALSE }, /* rfc6531 */
277 #endif
278 /* keep this the last entry */
279 { US"NULL", ENV_MAIL_OPT_NULL, FALSE },
280 };
281
282 /* When reading SMTP from a remote host, we have to use our own versions of the
283 C input-reading functions, in order to be able to flush the SMTP output only
284 when about to read more data from the socket. This is the only way to get
285 optimal performance when the client is using pipelining. Flushing for every
286 command causes a separate packet and reply packet each time; saving all the
287 responses up (when pipelining) combines them into one packet and one response.
288
289 For simplicity, these functions are used for *all* SMTP input, not only when
290 receiving over a socket. However, after setting up a secure socket (SSL), input
291 is read via the OpenSSL library, and another set of functions is used instead
292 (see tls.c).
293
294 These functions are set in the receive_getc etc. variables and called with the
295 same interface as the C functions. However, since there can only ever be
296 one incoming SMTP call, we just use a single buffer and flags. There is no need
297 to implement a complicated private FILE-like structure.*/
298
299 static uschar *smtp_inbuffer;
300 static uschar *smtp_inptr;
301 static uschar *smtp_inend;
302 static int smtp_had_eof;
303 static int smtp_had_error;
304
305
306 /* forward declarations */
307 static int smtp_read_command(BOOL check_sync, unsigned buffer_lim);
308 static int synprot_error(int type, int code, uschar *data, uschar *errmess);
309 static void smtp_quit_handler(uschar **, uschar **);
310 static void smtp_rset_handler(void);
311
312 /*************************************************
313 * Recheck synchronization *
314 *************************************************/
315
316 /* Synchronization checks can never be perfect because a packet may be on its
317 way but not arrived when the check is done. Normally, the checks happen when
318 commands are read: Exim ensures that there is no more input in the input buffer.
319 In normal cases, the response to the command will be fast, and there is no
320 further check.
321
322 However, for some commands an ACL is run, and that can include delays. In those
323 cases, it is useful to do another check on the input just before sending the
324 response. This also applies at the start of a connection. This function does
325 that check by means of the select() function, as long as the facility is not
326 disabled or inappropriate. A failure of select() is ignored.
327
328 When there is unwanted input, we read it so that it appears in the log of the
329 error.
330
331 Arguments: none
332 Returns: TRUE if all is well; FALSE if there is input pending
333 */
334
335 static BOOL
336 wouldblock_reading(void)
337 {
338 int fd, rc;
339 fd_set fds;
340 struct timeval tzero;
341
342 #ifdef SUPPORT_TLS
343 if (tls_in.active >= 0)
344 return !tls_could_read();
345 #endif
346
347 if (smtp_inptr < smtp_inend)
348 return FALSE;
349
350 fd = fileno(smtp_in);
351 FD_ZERO(&fds);
352 FD_SET(fd, &fds);
353 tzero.tv_sec = 0;
354 tzero.tv_usec = 0;
355 rc = select(fd + 1, (SELECT_ARG2_TYPE *)&fds, NULL, NULL, &tzero);
356
357 if (rc <= 0) return TRUE; /* Not ready to read */
358 rc = smtp_getc(GETC_BUFFER_UNLIMITED);
359 if (rc < 0) return TRUE; /* End of file or error */
360
361 smtp_ungetc(rc);
362 return FALSE;
363 }
364
365 static BOOL
366 check_sync(void)
367 {
368 if (!smtp_enforce_sync || !sender_host_address || sender_host_notsocket)
369 return TRUE;
370
371 return wouldblock_reading();
372 }
373
374
375 /* If there's input waiting (and we're doing pipelineing) then we can pipeline
376 a reponse with the one following. */
377
378 static BOOL
379 pipeline_response(void)
380 {
381 if ( !smtp_enforce_sync || !sender_host_address
382 || sender_host_notsocket || !pipelining_advertised)
383 return FALSE;
384
385 return !wouldblock_reading();
386 }
387
388
389
390 /*************************************************
391 * Log incomplete transactions *
392 *************************************************/
393
394 /* This function is called after a transaction has been aborted by RSET, QUIT,
395 connection drops or other errors. It logs the envelope information received
396 so far in order to preserve address verification attempts.
397
398 Argument: string to indicate what aborted the transaction
399 Returns: nothing
400 */
401
402 static void
403 incomplete_transaction_log(uschar *what)
404 {
405 if (sender_address == NULL || /* No transaction in progress */
406 !LOGGING(smtp_incomplete_transaction))
407 return;
408
409 /* Build list of recipients for logging */
410
411 if (recipients_count > 0)
412 {
413 int i;
414 raw_recipients = store_get(recipients_count * sizeof(uschar *));
415 for (i = 0; i < recipients_count; i++)
416 raw_recipients[i] = recipients_list[i].address;
417 raw_recipients_count = recipients_count;
418 }
419
420 log_write(L_smtp_incomplete_transaction, LOG_MAIN|LOG_SENDER|LOG_RECIPIENTS,
421 "%s incomplete transaction (%s)", host_and_ident(TRUE), what);
422 }
423
424
425
426
427 /* Refill the buffer, and notify DKIM verification code.
428 Return false for error or EOF.
429 */
430
431 static BOOL
432 smtp_refill(unsigned lim)
433 {
434 int rc, save_errno;
435 if (!smtp_out) return FALSE;
436 fflush(smtp_out);
437 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
438
439 /* Limit amount read, so non-message data is not fed to DKIM.
440 Take care to not touch the safety NUL at the end of the buffer. */
441
442 rc = read(fileno(smtp_in), smtp_inbuffer, MIN(IN_BUFFER_SIZE-1, lim));
443 save_errno = errno;
444 alarm(0);
445 if (rc <= 0)
446 {
447 /* Must put the error text in fixed store, because this might be during
448 header reading, where it releases unused store above the header. */
449 if (rc < 0)
450 {
451 smtp_had_error = save_errno;
452 smtp_read_error = string_copy_malloc(
453 string_sprintf(" (error: %s)", strerror(save_errno)));
454 }
455 else smtp_had_eof = 1;
456 return FALSE;
457 }
458 #ifndef DISABLE_DKIM
459 dkim_exim_verify_feed(smtp_inbuffer, rc);
460 #endif
461 smtp_inend = smtp_inbuffer + rc;
462 smtp_inptr = smtp_inbuffer;
463 return TRUE;
464 }
465
466 /*************************************************
467 * SMTP version of getc() *
468 *************************************************/
469
470 /* This gets the next byte from the SMTP input buffer. If the buffer is empty,
471 it flushes the output, and refills the buffer, with a timeout. The signal
472 handler is set appropriately by the calling function. This function is not used
473 after a connection has negotiated itself into an TLS/SSL state.
474
475 Arguments: lim Maximum amount to read/buffer
476 Returns: the next character or EOF
477 */
478
479 int
480 smtp_getc(unsigned lim)
481 {
482 if (smtp_inptr >= smtp_inend)
483 if (!smtp_refill(lim))
484 return EOF;
485 return *smtp_inptr++;
486 }
487
488 uschar *
489 smtp_getbuf(unsigned * len)
490 {
491 unsigned size;
492 uschar * buf;
493
494 if (smtp_inptr >= smtp_inend)
495 if (!smtp_refill(*len))
496 { *len = 0; return NULL; }
497
498 if ((size = smtp_inend - smtp_inptr) > *len) size = *len;
499 buf = smtp_inptr;
500 smtp_inptr += size;
501 *len = size;
502 return buf;
503 }
504
505 void
506 smtp_get_cache(void)
507 {
508 #ifndef DISABLE_DKIM
509 int n = smtp_inend - smtp_inptr;
510 if (n > 0)
511 dkim_exim_verify_feed(smtp_inptr, n);
512 #endif
513 }
514
515
516 /* Get a byte from the smtp input, in CHUNKING mode. Handle ack of the
517 previous BDAT chunk and getting new ones when we run out. Uses the
518 underlying smtp_getc or tls_getc both for that and for getting the
519 (buffered) data byte. EOD signals (an expected) no further data.
520 ERR signals a protocol error, and EOF a closed input stream.
521
522 Called from read_bdat_smtp() in receive.c for the message body, but also
523 by the headers read loop in receive_msg(); manipulates chunking_state
524 to handle the BDAT command/response.
525 Placed here due to the correlation with the above smtp_getc(), which it wraps,
526 and also by the need to do smtp command/response handling.
527
528 Arguments: lim (ignored)
529 Returns: the next character or ERR, EOD or EOF
530 */
531
532 int
533 bdat_getc(unsigned lim)
534 {
535 uschar * user_msg = NULL;
536 uschar * log_msg;
537
538 for(;;)
539 {
540 #ifndef DISABLE_DKIM
541 BOOL dkim_save;
542 #endif
543
544 if (chunking_data_left > 0)
545 return lwr_receive_getc(chunking_data_left--);
546
547 receive_getc = lwr_receive_getc;
548 receive_getbuf = lwr_receive_getbuf;
549 receive_ungetc = lwr_receive_ungetc;
550 #ifndef DISABLE_DKIM
551 dkim_save = dkim_collect_input;
552 dkim_collect_input = FALSE;
553 #endif
554
555 /* Unless PIPELINING was offered, there should be no next command
556 until after we ack that chunk */
557
558 if (!pipelining_advertised && !check_sync())
559 {
560 unsigned n = smtp_inend - smtp_inptr;
561 if (n > 32) n = 32;
562
563 incomplete_transaction_log(US"sync failure");
564 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP protocol synchronization error "
565 "(next input sent too soon: pipelining was not advertised): "
566 "rejected \"%s\" %s next input=\"%s\"%s",
567 smtp_cmd_buffer, host_and_ident(TRUE),
568 string_printing(string_copyn(smtp_inptr, n)),
569 smtp_inend - smtp_inptr > n ? "..." : "");
570 (void) synprot_error(L_smtp_protocol_error, 554, NULL,
571 US"SMTP synchronization error");
572 goto repeat_until_rset;
573 }
574
575 /* If not the last, ack the received chunk. The last response is delayed
576 until after the data ACL decides on it */
577
578 if (chunking_state == CHUNKING_LAST)
579 {
580 #ifndef DISABLE_DKIM
581 dkim_exim_verify_feed(NULL, 0); /* notify EOD */
582 #endif
583 return EOD;
584 }
585
586 smtp_printf("250 %u byte chunk received\r\n", FALSE, chunking_datasize);
587 chunking_state = CHUNKING_OFFERED;
588 DEBUG(D_receive) debug_printf("chunking state %d\n", (int)chunking_state);
589
590 /* Expect another BDAT cmd from input. RFC 3030 says nothing about
591 QUIT, RSET or NOOP but handling them seems obvious */
592
593 next_cmd:
594 switch(smtp_read_command(TRUE, 1))
595 {
596 default:
597 (void) synprot_error(L_smtp_protocol_error, 503, NULL,
598 US"only BDAT permissible after non-LAST BDAT");
599
600 repeat_until_rset:
601 switch(smtp_read_command(TRUE, 1))
602 {
603 case QUIT_CMD: smtp_quit_handler(&user_msg, &log_msg); /*FALLTHROUGH */
604 case EOF_CMD: return EOF;
605 case RSET_CMD: smtp_rset_handler(); return ERR;
606 default: if (synprot_error(L_smtp_protocol_error, 503, NULL,
607 US"only RSET accepted now") > 0)
608 return EOF;
609 goto repeat_until_rset;
610 }
611
612 case QUIT_CMD:
613 smtp_quit_handler(&user_msg, &log_msg);
614 /*FALLTHROUGH*/
615 case EOF_CMD:
616 return EOF;
617
618 case RSET_CMD:
619 smtp_rset_handler();
620 return ERR;
621
622 case NOOP_CMD:
623 HAD(SCH_NOOP);
624 smtp_printf("250 OK\r\n", FALSE);
625 goto next_cmd;
626
627 case BDAT_CMD:
628 {
629 int n;
630
631 if (sscanf(CS smtp_cmd_data, "%u %n", &chunking_datasize, &n) < 1)
632 {
633 (void) synprot_error(L_smtp_protocol_error, 501, NULL,
634 US"missing size for BDAT command");
635 return ERR;
636 }
637 chunking_state = strcmpic(smtp_cmd_data+n, US"LAST") == 0
638 ? CHUNKING_LAST : CHUNKING_ACTIVE;
639 chunking_data_left = chunking_datasize;
640 DEBUG(D_receive) debug_printf("chunking state %d, %d bytes\n",
641 (int)chunking_state, chunking_data_left);
642
643 if (chunking_datasize == 0)
644 if (chunking_state == CHUNKING_LAST)
645 return EOD;
646 else
647 {
648 (void) synprot_error(L_smtp_protocol_error, 504, NULL,
649 US"zero size for BDAT command");
650 goto repeat_until_rset;
651 }
652
653 receive_getc = bdat_getc;
654 receive_getbuf = bdat_getbuf; /* r~getbuf is never actually used */
655 receive_ungetc = bdat_ungetc;
656 #ifndef DISABLE_DKIM
657 dkim_collect_input = dkim_save;
658 #endif
659 break; /* to top of main loop */
660 }
661 }
662 }
663 }
664
665 uschar *
666 bdat_getbuf(unsigned * len)
667 {
668 uschar * buf;
669
670 if (chunking_data_left <= 0)
671 { *len = 0; return NULL; }
672
673 if (*len > chunking_data_left) *len = chunking_data_left;
674 buf = lwr_receive_getbuf(len); /* Either smtp_getbuf or tls_getbuf */
675 chunking_data_left -= *len;
676 return buf;
677 }
678
679 void
680 bdat_flush_data(void)
681 {
682 while (chunking_data_left)
683 {
684 unsigned n = chunking_data_left;
685 if (!bdat_getbuf(&n)) break;
686 }
687
688 receive_getc = lwr_receive_getc;
689 receive_getbuf = lwr_receive_getbuf;
690 receive_ungetc = lwr_receive_ungetc;
691
692 if (chunking_state != CHUNKING_LAST)
693 {
694 chunking_state = CHUNKING_OFFERED;
695 DEBUG(D_receive) debug_printf("chunking state %d\n", (int)chunking_state);
696 }
697 }
698
699
700
701
702 /*************************************************
703 * SMTP version of ungetc() *
704 *************************************************/
705
706 /* Puts a character back in the input buffer. Only ever
707 called once.
708
709 Arguments:
710 ch the character
711
712 Returns: the character
713 */
714
715 int
716 smtp_ungetc(int ch)
717 {
718 *--smtp_inptr = ch;
719 return ch;
720 }
721
722
723 int
724 bdat_ungetc(int ch)
725 {
726 chunking_data_left++;
727 return lwr_receive_ungetc(ch);
728 }
729
730
731
732 /*************************************************
733 * SMTP version of feof() *
734 *************************************************/
735
736 /* Tests for a previous EOF
737
738 Arguments: none
739 Returns: non-zero if the eof flag is set
740 */
741
742 int
743 smtp_feof(void)
744 {
745 return smtp_had_eof;
746 }
747
748
749
750
751 /*************************************************
752 * SMTP version of ferror() *
753 *************************************************/
754
755 /* Tests for a previous read error, and returns with errno
756 restored to what it was when the error was detected.
757
758 Arguments: none
759 Returns: non-zero if the error flag is set
760 */
761
762 int
763 smtp_ferror(void)
764 {
765 errno = smtp_had_error;
766 return smtp_had_error;
767 }
768
769
770
771 /*************************************************
772 * Test for characters in the SMTP buffer *
773 *************************************************/
774
775 /* Used at the end of a message
776
777 Arguments: none
778 Returns: TRUE/FALSE
779 */
780
781 BOOL
782 smtp_buffered(void)
783 {
784 return smtp_inptr < smtp_inend;
785 }
786
787
788
789 /*************************************************
790 * Write formatted string to SMTP channel *
791 *************************************************/
792
793 /* This is a separate function so that we don't have to repeat everything for
794 TLS support or debugging. It is global so that the daemon and the
795 authentication functions can use it. It does not return any error indication,
796 because major problems such as dropped connections won't show up till an output
797 flush for non-TLS connections. The smtp_fflush() function is available for
798 checking that: for convenience, TLS output errors are remembered here so that
799 they are also picked up later by smtp_fflush().
800
801 Arguments:
802 format format string
803 more further data expected
804 ... optional arguments
805
806 Returns: nothing
807 */
808
809 void
810 smtp_printf(const char *format, BOOL more, ...)
811 {
812 va_list ap;
813
814 va_start(ap, more);
815 smtp_vprintf(format, more, ap);
816 va_end(ap);
817 }
818
819 /* This is split off so that verify.c:respond_printf() can, in effect, call
820 smtp_printf(), bearing in mind that in C a vararg function can't directly
821 call another vararg function, only a function which accepts a va_list. */
822
823 void
824 smtp_vprintf(const char *format, BOOL more, va_list ap)
825 {
826 BOOL yield;
827
828 yield = string_vformat(big_buffer, big_buffer_size, format, ap);
829
830 DEBUG(D_receive)
831 {
832 void *reset_point = store_get(0);
833 uschar *msg_copy, *cr, *end;
834 msg_copy = string_copy(big_buffer);
835 end = msg_copy + Ustrlen(msg_copy);
836 while ((cr = Ustrchr(msg_copy, '\r')) != NULL) /* lose CRs */
837 memmove(cr, cr + 1, (end--) - cr);
838 debug_printf("SMTP>> %s", msg_copy);
839 store_reset(reset_point);
840 }
841
842 if (!yield)
843 {
844 log_write(0, LOG_MAIN|LOG_PANIC, "string too large in smtp_printf()");
845 smtp_closedown(US"Unexpected error");
846 exim_exit(EXIT_FAILURE, NULL);
847 }
848
849 /* If this is the first output for a (non-batch) RCPT command, see if all RCPTs
850 have had the same. Note: this code is also present in smtp_respond(). It would
851 be tidier to have it only in one place, but when it was added, it was easier to
852 do it that way, so as not to have to mess with the code for the RCPT command,
853 which sometimes uses smtp_printf() and sometimes smtp_respond(). */
854
855 if (rcpt_in_progress)
856 {
857 if (rcpt_smtp_response == NULL)
858 rcpt_smtp_response = string_copy(big_buffer);
859 else if (rcpt_smtp_response_same &&
860 Ustrcmp(rcpt_smtp_response, big_buffer) != 0)
861 rcpt_smtp_response_same = FALSE;
862 rcpt_in_progress = FALSE;
863 }
864
865 /* Now write the string */
866
867 #ifdef SUPPORT_TLS
868 if (tls_in.active >= 0)
869 {
870 if (tls_write(TRUE, big_buffer, Ustrlen(big_buffer), more) < 0)
871 smtp_write_error = -1;
872 }
873 else
874 #endif
875
876 if (fprintf(smtp_out, "%s", big_buffer) < 0) smtp_write_error = -1;
877 }
878
879
880
881 /*************************************************
882 * Flush SMTP out and check for error *
883 *************************************************/
884
885 /* This function isn't currently used within Exim (it detects errors when it
886 tries to read the next SMTP input), but is available for use in local_scan().
887 For non-TLS connections, it flushes the output and checks for errors. For
888 TLS-connections, it checks for a previously-detected TLS write error.
889
890 Arguments: none
891 Returns: 0 for no error; -1 after an error
892 */
893
894 int
895 smtp_fflush(void)
896 {
897 if (tls_in.active < 0 && fflush(smtp_out) != 0) smtp_write_error = -1;
898 return smtp_write_error;
899 }
900
901
902
903 /*************************************************
904 * SMTP command read timeout *
905 *************************************************/
906
907 /* Signal handler for timing out incoming SMTP commands. This attempts to
908 finish off tidily.
909
910 Argument: signal number (SIGALRM)
911 Returns: nothing
912 */
913
914 static void
915 command_timeout_handler(int sig)
916 {
917 sig = sig; /* Keep picky compilers happy */
918 log_write(L_lost_incoming_connection,
919 LOG_MAIN, "SMTP command timeout on%s connection from %s",
920 (tls_in.active >= 0)? " TLS" : "",
921 host_and_ident(FALSE));
922 if (smtp_batched_input)
923 moan_smtp_batch(NULL, "421 SMTP command timeout"); /* Does not return */
924 smtp_notquit_exit(US"command-timeout", US"421",
925 US"%s: SMTP command timeout - closing connection", smtp_active_hostname);
926 exim_exit(EXIT_FAILURE, US"receiving");
927 }
928
929
930
931 /*************************************************
932 * SIGTERM received *
933 *************************************************/
934
935 /* Signal handler for handling SIGTERM. Again, try to finish tidily.
936
937 Argument: signal number (SIGTERM)
938 Returns: nothing
939 */
940
941 static void
942 command_sigterm_handler(int sig)
943 {
944 sig = sig; /* Keep picky compilers happy */
945 log_write(0, LOG_MAIN, "%s closed after SIGTERM", smtp_get_connection_info());
946 if (smtp_batched_input)
947 moan_smtp_batch(NULL, "421 SIGTERM received"); /* Does not return */
948 smtp_notquit_exit(US"signal-exit", US"421",
949 US"%s: Service not available - closing connection", smtp_active_hostname);
950 exim_exit(EXIT_FAILURE, US"receiving");
951 }
952
953
954
955
956 #ifdef SUPPORT_PROXY
957 /*************************************************
958 * Restore socket timeout to previous value *
959 *************************************************/
960 /* If the previous value was successfully retrieved, restore
961 it before returning control to the non-proxy routines
962
963 Arguments: fd - File descriptor for input
964 get_ok - Successfully retrieved previous values
965 tvtmp - Time struct with previous values
966 vslen - Length of time struct
967 Returns: none
968 */
969 static void
970 restore_socket_timeout(int fd, int get_ok, struct timeval * tvtmp, socklen_t vslen)
971 {
972 if (get_ok == 0)
973 (void) setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, CS tvtmp, vslen);
974 }
975
976 /*************************************************
977 * Check if host is required proxy host *
978 *************************************************/
979 /* The function determines if inbound host will be a regular smtp host
980 or if it is configured that it must use Proxy Protocol. A local
981 connection cannot.
982
983 Arguments: none
984 Returns: bool
985 */
986
987 static BOOL
988 check_proxy_protocol_host()
989 {
990 int rc;
991
992 if ( sender_host_address
993 && (rc = verify_check_this_host(CUSS &hosts_proxy, NULL, NULL,
994 sender_host_address, NULL)) == OK)
995 {
996 DEBUG(D_receive)
997 debug_printf("Detected proxy protocol configured host\n");
998 proxy_session = TRUE;
999 }
1000 return proxy_session;
1001 }
1002
1003
1004 /*************************************************
1005 * Read data until newline or end of buffer *
1006 *************************************************/
1007 /* While SMTP is server-speaks-first, TLS is client-speaks-first, so we can't
1008 read an entire buffer and assume there will be nothing past a proxy protocol
1009 header. Our approach normally is to use stdio, but again that relies upon
1010 "STARTTLS\r\n" and a server response before the client starts TLS handshake, or
1011 reading _nothing_ before client TLS handshake. So we don't want to use the
1012 usual buffering reads which may read enough to block TLS starting.
1013
1014 So unfortunately we're down to "read one byte at a time, with a syscall each,
1015 and expect a little overhead", for all proxy-opened connections which are v1,
1016 just to handle the TLS-on-connect case. Since SSL functions wrap the
1017 underlying fd, we can't assume that we can feed them any already-read content.
1018
1019 We need to know where to read to, the max capacity, and we'll read until we
1020 get a CR and one more character. Let the caller scream if it's CR+!LF.
1021
1022 Return the amount read.
1023 */
1024
1025 static int
1026 swallow_until_crlf(int fd, uschar *base, int already, int capacity)
1027 {
1028 uschar *to = base + already;
1029 uschar *cr;
1030 int have = 0;
1031 int ret;
1032 int last = 0;
1033
1034 /* For "PROXY UNKNOWN\r\n" we, at time of writing, expect to have read
1035 up through the \r; for the _normal_ case, we haven't yet seen the \r. */
1036
1037 cr = memchr(base, '\r', already);
1038 if (cr != NULL)
1039 {
1040 if ((cr - base) < already - 1)
1041 {
1042 /* \r and presumed \n already within what we have; probably not
1043 actually proxy protocol, but abort cleanly. */
1044 return 0;
1045 }
1046 /* \r is last character read, just need one more. */
1047 last = 1;
1048 }
1049
1050 while (capacity > 0)
1051 {
1052 do { ret = recv(fd, to, 1, 0); } while (ret == -1 && errno == EINTR);
1053 if (ret == -1)
1054 return -1;
1055 have++;
1056 if (last)
1057 return have;
1058 if (*to == '\r')
1059 last = 1;
1060 capacity--;
1061 to++;
1062 }
1063
1064 /* reached end without having room for a final newline, abort */
1065 errno = EOVERFLOW;
1066 return -1;
1067 }
1068
1069 /*************************************************
1070 * Setup host for proxy protocol *
1071 *************************************************/
1072 /* The function configures the connection based on a header from the
1073 inbound host to use Proxy Protocol. The specification is very exact
1074 so exit with an error if do not find the exact required pieces. This
1075 includes an incorrect number of spaces separating args.
1076
1077 Arguments: none
1078 Returns: Boolean success
1079 */
1080
1081 static void
1082 setup_proxy_protocol_host()
1083 {
1084 union {
1085 struct {
1086 uschar line[108];
1087 } v1;
1088 struct {
1089 uschar sig[12];
1090 uint8_t ver_cmd;
1091 uint8_t fam;
1092 uint16_t len;
1093 union {
1094 struct { /* TCP/UDP over IPv4, len = 12 */
1095 uint32_t src_addr;
1096 uint32_t dst_addr;
1097 uint16_t src_port;
1098 uint16_t dst_port;
1099 } ip4;
1100 struct { /* TCP/UDP over IPv6, len = 36 */
1101 uint8_t src_addr[16];
1102 uint8_t dst_addr[16];
1103 uint16_t src_port;
1104 uint16_t dst_port;
1105 } ip6;
1106 struct { /* AF_UNIX sockets, len = 216 */
1107 uschar src_addr[108];
1108 uschar dst_addr[108];
1109 } unx;
1110 } addr;
1111 } v2;
1112 } hdr;
1113
1114 /* Temp variables used in PPv2 address:port parsing */
1115 uint16_t tmpport;
1116 char tmpip[INET_ADDRSTRLEN];
1117 struct sockaddr_in tmpaddr;
1118 char tmpip6[INET6_ADDRSTRLEN];
1119 struct sockaddr_in6 tmpaddr6;
1120
1121 /* We can't read "all data until end" because while SMTP is
1122 server-speaks-first, the TLS handshake is client-speaks-first, so for
1123 TLS-on-connect ports the proxy protocol header will usually be immediately
1124 followed by a TLS handshake, and with N TLS libraries, we can't reliably
1125 reinject data for reading by those. So instead we first read "enough to be
1126 safely read within the header, and figure out how much more to read".
1127 For v1 we will later read to the end-of-line, for v2 we will read based upon
1128 the stated length.
1129
1130 The v2 sig is 12 octets, and another 4 gets us the length, so we know how much
1131 data is needed total. For v1, where the line looks like:
1132 PROXY TCPn L3src L3dest SrcPort DestPort \r\n
1133
1134 However, for v1 there's also `PROXY UNKNOWN\r\n` which is only 15 octets.
1135 We seem to support that. So, if we read 14 octets then we can tell if we're
1136 v2 or v1. If we're v1, we can continue reading as normal.
1137
1138 If we're v2, we can't slurp up the entire header. We need the length in the
1139 15th & 16th octets, then to read everything after that.
1140
1141 So to safely handle v1 and v2, with client-sent-first supported correctly,
1142 we have to do a minimum of 3 read calls, not 1. Eww.
1143 */
1144
1145 #define PROXY_INITIAL_READ 14
1146 #define PROXY_V2_HEADER_SIZE 16
1147 #if PROXY_INITIAL_READ > PROXY_V2_HEADER_SIZE
1148 # error Code bug in sizes of data to read for proxy usage
1149 #endif
1150
1151 int get_ok = 0;
1152 int size, ret;
1153 int fd = fileno(smtp_in);
1154 const char v2sig[12] = "\x0D\x0A\x0D\x0A\x00\x0D\x0A\x51\x55\x49\x54\x0A";
1155 uschar * iptype; /* To display debug info */
1156 struct timeval tv;
1157 struct timeval tvtmp;
1158 socklen_t vslen = sizeof(struct timeval);
1159 BOOL yield = FALSE;
1160
1161 /* Save current socket timeout values */
1162 get_ok = getsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, CS &tvtmp, &vslen);
1163
1164 /* Proxy Protocol host must send header within a short time
1165 (default 3 seconds) or it's considered invalid */
1166 tv.tv_sec = PROXY_NEGOTIATION_TIMEOUT_SEC;
1167 tv.tv_usec = PROXY_NEGOTIATION_TIMEOUT_USEC;
1168 if (setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, CS &tv, sizeof(tv)) < 0)
1169 goto bad;
1170
1171 do
1172 {
1173 /* The inbound host was declared to be a Proxy Protocol host, so
1174 don't do a PEEK into the data, actually slurp up enough to be
1175 "safe". Can't take it all because TLS-on-connect clients follow
1176 immediately with TLS handshake. */
1177 ret = recv(fd, &hdr, PROXY_INITIAL_READ, 0);
1178 }
1179 while (ret == -1 && errno == EINTR);
1180
1181 if (ret == -1)
1182 goto proxyfail;
1183
1184 /* For v2, handle reading the length, and then the rest. */
1185 if ((ret == PROXY_INITIAL_READ) && (memcmp(&hdr.v2, v2sig, sizeof(v2sig)) == 0))
1186 {
1187 int retmore;
1188 uint8_t ver;
1189
1190 /* First get the length fields. */
1191 do
1192 {
1193 retmore = recv(fd, (uschar*)&hdr + ret, PROXY_V2_HEADER_SIZE - PROXY_INITIAL_READ, 0);
1194 } while (retmore == -1 && errno == EINTR);
1195 if (retmore == -1)
1196 goto proxyfail;
1197 ret += retmore;
1198
1199 ver = (hdr.v2.ver_cmd & 0xf0) >> 4;
1200
1201 /* May 2014: haproxy combined the version and command into one byte to
1202 allow two full bytes for the length field in order to proxy SSL
1203 connections. SSL Proxy is not supported in this version of Exim, but
1204 must still separate values here. */
1205
1206 if (ver != 0x02)
1207 {
1208 DEBUG(D_receive) debug_printf("Invalid Proxy Protocol version: %d\n", ver);
1209 goto proxyfail;
1210 }
1211
1212 /* The v2 header will always be 16 bytes per the spec. */
1213 size = 16 + ntohs(hdr.v2.len);
1214 DEBUG(D_receive) debug_printf("Detected PROXYv2 header, size %d (limit %d)\n",
1215 size, (int)sizeof(hdr));
1216
1217 /* We should now have 16 octets (PROXY_V2_HEADER_SIZE), and we know the total
1218 amount that we need. Double-check that the size is not unreasonable, then
1219 get the rest. */
1220 if (size > sizeof(hdr))
1221 {
1222 DEBUG(D_receive) debug_printf("PROXYv2 header size unreasonably large; security attack?\n");
1223 goto proxyfail;
1224 }
1225
1226 do
1227 {
1228 do
1229 {
1230 retmore = recv(fd, (uschar*)&hdr + ret, size-ret, 0);
1231 } while (retmore == -1 && errno == EINTR);
1232 if (retmore == -1)
1233 goto proxyfail;
1234 ret += retmore;
1235 DEBUG(D_receive) debug_printf("PROXYv2: have %d/%d required octets\n", ret, size);
1236 } while (ret < size);
1237
1238 } /* end scope for getting rest of data for v2 */
1239
1240 /* At this point: if PROXYv2, we've read the exact size required for all data;
1241 if PROXYv1 then we've read "less than required for any valid line" and should
1242 read the rest". */
1243
1244 if (ret >= 16 && memcmp(&hdr.v2, v2sig, 12) == 0)
1245 {
1246 uint8_t cmd = (hdr.v2.ver_cmd & 0x0f);
1247
1248 switch (cmd)
1249 {
1250 case 0x01: /* PROXY command */
1251 switch (hdr.v2.fam)
1252 {
1253 case 0x11: /* TCPv4 address type */
1254 iptype = US"IPv4";
1255 tmpaddr.sin_addr.s_addr = hdr.v2.addr.ip4.src_addr;
1256 inet_ntop(AF_INET, &tmpaddr.sin_addr, CS &tmpip, sizeof(tmpip));
1257 if (!string_is_ip_address(US tmpip, NULL))
1258 {
1259 DEBUG(D_receive) debug_printf("Invalid %s source IP\n", iptype);
1260 goto proxyfail;
1261 }
1262 proxy_local_address = sender_host_address;
1263 sender_host_address = string_copy(US tmpip);
1264 tmpport = ntohs(hdr.v2.addr.ip4.src_port);
1265 proxy_local_port = sender_host_port;
1266 sender_host_port = tmpport;
1267 /* Save dest ip/port */
1268 tmpaddr.sin_addr.s_addr = hdr.v2.addr.ip4.dst_addr;
1269 inet_ntop(AF_INET, &tmpaddr.sin_addr, CS &tmpip, sizeof(tmpip));
1270 if (!string_is_ip_address(US tmpip, NULL))
1271 {
1272 DEBUG(D_receive) debug_printf("Invalid %s dest port\n", iptype);
1273 goto proxyfail;
1274 }
1275 proxy_external_address = string_copy(US tmpip);
1276 tmpport = ntohs(hdr.v2.addr.ip4.dst_port);
1277 proxy_external_port = tmpport;
1278 goto done;
1279 case 0x21: /* TCPv6 address type */
1280 iptype = US"IPv6";
1281 memmove(tmpaddr6.sin6_addr.s6_addr, hdr.v2.addr.ip6.src_addr, 16);
1282 inet_ntop(AF_INET6, &tmpaddr6.sin6_addr, CS &tmpip6, sizeof(tmpip6));
1283 if (!string_is_ip_address(US tmpip6, NULL))
1284 {
1285 DEBUG(D_receive) debug_printf("Invalid %s source IP\n", iptype);
1286 goto proxyfail;
1287 }
1288 proxy_local_address = sender_host_address;
1289 sender_host_address = string_copy(US tmpip6);
1290 tmpport = ntohs(hdr.v2.addr.ip6.src_port);
1291 proxy_local_port = sender_host_port;
1292 sender_host_port = tmpport;
1293 /* Save dest ip/port */
1294 memmove(tmpaddr6.sin6_addr.s6_addr, hdr.v2.addr.ip6.dst_addr, 16);
1295 inet_ntop(AF_INET6, &tmpaddr6.sin6_addr, CS &tmpip6, sizeof(tmpip6));
1296 if (!string_is_ip_address(US tmpip6, NULL))
1297 {
1298 DEBUG(D_receive) debug_printf("Invalid %s dest port\n", iptype);
1299 goto proxyfail;
1300 }
1301 proxy_external_address = string_copy(US tmpip6);
1302 tmpport = ntohs(hdr.v2.addr.ip6.dst_port);
1303 proxy_external_port = tmpport;
1304 goto done;
1305 default:
1306 DEBUG(D_receive)
1307 debug_printf("Unsupported PROXYv2 connection type: 0x%02x\n",
1308 hdr.v2.fam);
1309 goto proxyfail;
1310 }
1311 /* Unsupported protocol, keep local connection address */
1312 break;
1313 case 0x00: /* LOCAL command */
1314 /* Keep local connection address for LOCAL */
1315 iptype = US"local";
1316 break;
1317 default:
1318 DEBUG(D_receive)
1319 debug_printf("Unsupported PROXYv2 command: 0x%x\n", cmd);
1320 goto proxyfail;
1321 }
1322 }
1323 else if (ret >= 8 && memcmp(hdr.v1.line, "PROXY", 5) == 0)
1324 {
1325 uschar *p;
1326 uschar *end;
1327 uschar *sp; /* Utility variables follow */
1328 int tmp_port;
1329 int r2;
1330 char *endc;
1331
1332 /* get the rest of the line */
1333 r2 = swallow_until_crlf(fd, (uschar*)&hdr, ret, sizeof(hdr)-ret);
1334 if (r2 == -1)
1335 goto proxyfail;
1336 ret += r2;
1337
1338 p = string_copy(hdr.v1.line);
1339 end = memchr(p, '\r', ret - 1);
1340
1341 if (!end || (end == (uschar*)&hdr + ret) || end[1] != '\n')
1342 {
1343 DEBUG(D_receive) debug_printf("Partial or invalid PROXY header\n");
1344 goto proxyfail;
1345 }
1346 *end = '\0'; /* Terminate the string */
1347 size = end + 2 - p; /* Skip header + CRLF */
1348 DEBUG(D_receive) debug_printf("Detected PROXYv1 header\n");
1349 DEBUG(D_receive) debug_printf("Bytes read not within PROXY header: %d\n", ret - size);
1350 /* Step through the string looking for the required fields. Ensure
1351 strict adherence to required formatting, exit for any error. */
1352 p += 5;
1353 if (!isspace(*(p++)))
1354 {
1355 DEBUG(D_receive) debug_printf("Missing space after PROXY command\n");
1356 goto proxyfail;
1357 }
1358 if (!Ustrncmp(p, CCS"TCP4", 4))
1359 iptype = US"IPv4";
1360 else if (!Ustrncmp(p,CCS"TCP6", 4))
1361 iptype = US"IPv6";
1362 else if (!Ustrncmp(p,CCS"UNKNOWN", 7))
1363 {
1364 iptype = US"Unknown";
1365 goto done;
1366 }
1367 else
1368 {
1369 DEBUG(D_receive) debug_printf("Invalid TCP type\n");
1370 goto proxyfail;
1371 }
1372
1373 p += Ustrlen(iptype);
1374 if (!isspace(*(p++)))
1375 {
1376 DEBUG(D_receive) debug_printf("Missing space after TCP4/6 command\n");
1377 goto proxyfail;
1378 }
1379 /* Find the end of the arg */
1380 if ((sp = Ustrchr(p, ' ')) == NULL)
1381 {
1382 DEBUG(D_receive)
1383 debug_printf("Did not find proxied src %s\n", iptype);
1384 goto proxyfail;
1385 }
1386 *sp = '\0';
1387 if(!string_is_ip_address(p, NULL))
1388 {
1389 DEBUG(D_receive)
1390 debug_printf("Proxied src arg is not an %s address\n", iptype);
1391 goto proxyfail;
1392 }
1393 proxy_local_address = sender_host_address;
1394 sender_host_address = p;
1395 p = sp + 1;
1396 if ((sp = Ustrchr(p, ' ')) == NULL)
1397 {
1398 DEBUG(D_receive)
1399 debug_printf("Did not find proxy dest %s\n", iptype);
1400 goto proxyfail;
1401 }
1402 *sp = '\0';
1403 if(!string_is_ip_address(p, NULL))
1404 {
1405 DEBUG(D_receive)
1406 debug_printf("Proxy dest arg is not an %s address\n", iptype);
1407 goto proxyfail;
1408 }
1409 proxy_external_address = p;
1410 p = sp + 1;
1411 if ((sp = Ustrchr(p, ' ')) == NULL)
1412 {
1413 DEBUG(D_receive) debug_printf("Did not find proxied src port\n");
1414 goto proxyfail;
1415 }
1416 *sp = '\0';
1417 tmp_port = strtol(CCS p, &endc, 10);
1418 if (*endc || tmp_port == 0)
1419 {
1420 DEBUG(D_receive)
1421 debug_printf("Proxied src port '%s' not an integer\n", p);
1422 goto proxyfail;
1423 }
1424 proxy_local_port = sender_host_port;
1425 sender_host_port = tmp_port;
1426 p = sp + 1;
1427 if ((sp = Ustrchr(p, '\0')) == NULL)
1428 {
1429 DEBUG(D_receive) debug_printf("Did not find proxy dest port\n");
1430 goto proxyfail;
1431 }
1432 tmp_port = strtol(CCS p, &endc, 10);
1433 if (*endc || tmp_port == 0)
1434 {
1435 DEBUG(D_receive)
1436 debug_printf("Proxy dest port '%s' not an integer\n", p);
1437 goto proxyfail;
1438 }
1439 proxy_external_port = tmp_port;
1440 /* Already checked for /r /n above. Good V1 header received. */
1441 }
1442 else
1443 {
1444 /* Wrong protocol */
1445 DEBUG(D_receive) debug_printf("Invalid proxy protocol version negotiation\n");
1446 (void) swallow_until_crlf(fd, (uschar*)&hdr, ret, sizeof(hdr)-ret);
1447 goto proxyfail;
1448 }
1449
1450 done:
1451 DEBUG(D_receive)
1452 debug_printf("Valid %s sender from Proxy Protocol header\n", iptype);
1453 yield = proxy_session;
1454
1455 /* Don't flush any potential buffer contents. Any input on proxyfail
1456 should cause a synchronization failure */
1457
1458 proxyfail:
1459 restore_socket_timeout(fd, get_ok, &tvtmp, vslen);
1460
1461 bad:
1462 if (yield)
1463 {
1464 sender_host_name = NULL;
1465 (void) host_name_lookup();
1466 host_build_sender_fullhost();
1467 }
1468 else
1469 {
1470 proxy_session_failed = TRUE;
1471 DEBUG(D_receive)
1472 debug_printf("Failure to extract proxied host, only QUIT allowed\n");
1473 }
1474
1475 return;
1476 }
1477 #endif
1478
1479 /*************************************************
1480 * Read one command line *
1481 *************************************************/
1482
1483 /* Strictly, SMTP commands coming over the net are supposed to end with CRLF.
1484 There are sites that don't do this, and in any case internal SMTP probably
1485 should check only for LF. Consequently, we check here for LF only. The line
1486 ends up with [CR]LF removed from its end. If we get an overlong line, treat as
1487 an unknown command. The command is read into the global smtp_cmd_buffer so that
1488 it is available via $smtp_command.
1489
1490 The character reading routine sets up a timeout for each block actually read
1491 from the input (which may contain more than one command). We set up a special
1492 signal handler that closes down the session on a timeout. Control does not
1493 return when it runs.
1494
1495 Arguments:
1496 check_sync if TRUE, check synchronization rules if global option is TRUE
1497 buffer_lim maximum to buffer in lower layer
1498
1499 Returns: a code identifying the command (enumerated above)
1500 */
1501
1502 static int
1503 smtp_read_command(BOOL check_sync, unsigned buffer_lim)
1504 {
1505 int c;
1506 int ptr = 0;
1507 smtp_cmd_list *p;
1508 BOOL hadnull = FALSE;
1509
1510 os_non_restarting_signal(SIGALRM, command_timeout_handler);
1511
1512 while ((c = (receive_getc)(buffer_lim)) != '\n' && c != EOF)
1513 {
1514 if (ptr >= SMTP_CMD_BUFFER_SIZE)
1515 {
1516 os_non_restarting_signal(SIGALRM, sigalrm_handler);
1517 return OTHER_CMD;
1518 }
1519 if (c == 0)
1520 {
1521 hadnull = TRUE;
1522 c = '?';
1523 }
1524 smtp_cmd_buffer[ptr++] = c;
1525 }
1526
1527 receive_linecount++; /* For BSMTP errors */
1528 os_non_restarting_signal(SIGALRM, sigalrm_handler);
1529
1530 /* If hit end of file, return pseudo EOF command. Whether we have a
1531 part-line already read doesn't matter, since this is an error state. */
1532
1533 if (c == EOF) return EOF_CMD;
1534
1535 /* Remove any CR and white space at the end of the line, and terminate the
1536 string. */
1537
1538 while (ptr > 0 && isspace(smtp_cmd_buffer[ptr-1])) ptr--;
1539 smtp_cmd_buffer[ptr] = 0;
1540
1541 DEBUG(D_receive) debug_printf("SMTP<< %s\n", smtp_cmd_buffer);
1542
1543 /* NULLs are not allowed in SMTP commands */
1544
1545 if (hadnull) return BADCHAR_CMD;
1546
1547 /* Scan command list and return identity, having set the data pointer
1548 to the start of the actual data characters. Check for SMTP synchronization
1549 if required. */
1550
1551 for (p = cmd_list; p < cmd_list_end; p++)
1552 {
1553 #ifdef SUPPORT_PROXY
1554 /* Only allow QUIT command if Proxy Protocol parsing failed */
1555 if (proxy_session && proxy_session_failed && p->cmd != QUIT_CMD)
1556 continue;
1557 #endif
1558 if ( p->len
1559 && strncmpic(smtp_cmd_buffer, US p->name, p->len) == 0
1560 && ( smtp_cmd_buffer[p->len-1] == ':' /* "mail from:" or "rcpt to:" */
1561 || smtp_cmd_buffer[p->len] == 0
1562 || smtp_cmd_buffer[p->len] == ' '
1563 ) )
1564 {
1565 if (smtp_inptr < smtp_inend && /* Outstanding input */
1566 p->cmd < sync_cmd_limit && /* Command should sync */
1567 check_sync && /* Local flag set */
1568 smtp_enforce_sync && /* Global flag set */
1569 sender_host_address != NULL && /* Not local input */
1570 !sender_host_notsocket) /* Really is a socket */
1571 return BADSYN_CMD;
1572
1573 /* The variables $smtp_command and $smtp_command_argument point into the
1574 unmodified input buffer. A copy of the latter is taken for actual
1575 processing, so that it can be chopped up into separate parts if necessary,
1576 for example, when processing a MAIL command options such as SIZE that can
1577 follow the sender address. */
1578
1579 smtp_cmd_argument = smtp_cmd_buffer + p->len;
1580 while (isspace(*smtp_cmd_argument)) smtp_cmd_argument++;
1581 Ustrcpy(smtp_data_buffer, smtp_cmd_argument);
1582 smtp_cmd_data = smtp_data_buffer;
1583
1584 /* Count non-mail commands from those hosts that are controlled in this
1585 way. The default is all hosts. We don't waste effort checking the list
1586 until we get a non-mail command, but then cache the result to save checking
1587 again. If there's a DEFER while checking the host, assume it's in the list.
1588
1589 Note that one instance of RSET, EHLO/HELO, and STARTTLS is allowed at the
1590 start of each incoming message by fiddling with the value in the table. */
1591
1592 if (!p->is_mail_cmd)
1593 {
1594 if (count_nonmail == TRUE_UNSET) count_nonmail =
1595 verify_check_host(&smtp_accept_max_nonmail_hosts) != FAIL;
1596 if (count_nonmail && ++nonmail_command_count > smtp_accept_max_nonmail)
1597 return TOO_MANY_NONMAIL_CMD;
1598 }
1599
1600 /* If there is data for a command that does not expect it, generate the
1601 error here. */
1602
1603 return (p->has_arg || *smtp_cmd_data == 0)? p->cmd : BADARG_CMD;
1604 }
1605 }
1606
1607 #ifdef SUPPORT_PROXY
1608 /* Only allow QUIT command if Proxy Protocol parsing failed */
1609 if (proxy_session && proxy_session_failed)
1610 return PROXY_FAIL_IGNORE_CMD;
1611 #endif
1612
1613 /* Enforce synchronization for unknown commands */
1614
1615 if ( smtp_inptr < smtp_inend /* Outstanding input */
1616 && check_sync /* Local flag set */
1617 && smtp_enforce_sync /* Global flag set */
1618 && sender_host_address /* Not local input */
1619 && !sender_host_notsocket) /* Really is a socket */
1620 return BADSYN_CMD;
1621
1622 return OTHER_CMD;
1623 }
1624
1625
1626
1627 /*************************************************
1628 * Forced closedown of call *
1629 *************************************************/
1630
1631 /* This function is called from log.c when Exim is dying because of a serious
1632 disaster, and also from some other places. If an incoming non-batched SMTP
1633 channel is open, it swallows the rest of the incoming message if in the DATA
1634 phase, sends the reply string, and gives an error to all subsequent commands
1635 except QUIT. The existence of an SMTP call is detected by the non-NULLness of
1636 smtp_in.
1637
1638 Arguments:
1639 message SMTP reply string to send, excluding the code
1640
1641 Returns: nothing
1642 */
1643
1644 void
1645 smtp_closedown(uschar *message)
1646 {
1647 if (!smtp_in || smtp_batched_input) return;
1648 receive_swallow_smtp();
1649 smtp_printf("421 %s\r\n", FALSE, message);
1650
1651 for (;;) switch(smtp_read_command(FALSE, GETC_BUFFER_UNLIMITED))
1652 {
1653 case EOF_CMD:
1654 return;
1655
1656 case QUIT_CMD:
1657 smtp_printf("221 %s closing connection\r\n", FALSE, smtp_active_hostname);
1658 mac_smtp_fflush();
1659 return;
1660
1661 case RSET_CMD:
1662 smtp_printf("250 Reset OK\r\n", FALSE);
1663 break;
1664
1665 default:
1666 smtp_printf("421 %s\r\n", FALSE, message);
1667 break;
1668 }
1669 }
1670
1671
1672
1673
1674 /*************************************************
1675 * Set up connection info for logging *
1676 *************************************************/
1677
1678 /* This function is called when logging information about an SMTP connection.
1679 It sets up appropriate source information, depending on the type of connection.
1680 If sender_fullhost is NULL, we are at a very early stage of the connection;
1681 just use the IP address.
1682
1683 Argument: none
1684 Returns: a string describing the connection
1685 */
1686
1687 uschar *
1688 smtp_get_connection_info(void)
1689 {
1690 const uschar * hostname = sender_fullhost
1691 ? sender_fullhost : sender_host_address;
1692
1693 if (host_checking)
1694 return string_sprintf("SMTP connection from %s", hostname);
1695
1696 if (sender_host_unknown || sender_host_notsocket)
1697 return string_sprintf("SMTP connection from %s", sender_ident);
1698
1699 if (is_inetd)
1700 return string_sprintf("SMTP connection from %s (via inetd)", hostname);
1701
1702 if (LOGGING(incoming_interface) && interface_address != NULL)
1703 return string_sprintf("SMTP connection from %s I=[%s]:%d", hostname,
1704 interface_address, interface_port);
1705
1706 return string_sprintf("SMTP connection from %s", hostname);
1707 }
1708
1709
1710
1711 #ifdef SUPPORT_TLS
1712 /* Append TLS-related information to a log line
1713
1714 Arguments:
1715 g String under construction: allocated string to extend, or NULL
1716
1717 Returns: Allocated string or NULL
1718 */
1719 static gstring *
1720 s_tlslog(gstring * g)
1721 {
1722 if (LOGGING(tls_cipher) && tls_in.cipher)
1723 g = string_append(g, 2, US" X=", tls_in.cipher);
1724 if (LOGGING(tls_certificate_verified) && tls_in.cipher)
1725 g = string_append(g, 2, US" CV=", tls_in.certificate_verified? "yes":"no");
1726 if (LOGGING(tls_peerdn) && tls_in.peerdn)
1727 g = string_append(g, 3, US" DN=\"", string_printing(tls_in.peerdn), US"\"");
1728 if (LOGGING(tls_sni) && tls_in.sni)
1729 g = string_append(g, 3, US" SNI=\"", string_printing(tls_in.sni), US"\"");
1730 return g;
1731 }
1732 #endif
1733
1734 /*************************************************
1735 * Log lack of MAIL if so configured *
1736 *************************************************/
1737
1738 /* This function is called when an SMTP session ends. If the log selector
1739 smtp_no_mail is set, write a log line giving some details of what has happened
1740 in the SMTP session.
1741
1742 Arguments: none
1743 Returns: nothing
1744 */
1745
1746 void
1747 smtp_log_no_mail(void)
1748 {
1749 int i;
1750 uschar * sep, * s;
1751 gstring * g = NULL;
1752
1753 if (smtp_mailcmd_count > 0 || !LOGGING(smtp_no_mail))
1754 return;
1755
1756 if (sender_host_authenticated)
1757 {
1758 g = string_append(g, 2, US" A=", sender_host_authenticated);
1759 if (authenticated_id) g = string_append(g, 2, US":", authenticated_id);
1760 }
1761
1762 #ifdef SUPPORT_TLS
1763 g = s_tlslog(g);
1764 #endif
1765
1766 sep = smtp_connection_had[SMTP_HBUFF_SIZE-1] != SCH_NONE ? US" C=..." : US" C=";
1767
1768 for (i = smtp_ch_index; i < SMTP_HBUFF_SIZE; i++)
1769 if (smtp_connection_had[i] != SCH_NONE)
1770 {
1771 g = string_append(g, 2, sep, smtp_names[smtp_connection_had[i]]);
1772 sep = US",";
1773 }
1774
1775 for (i = 0; i < smtp_ch_index; i++)
1776 {
1777 g = string_append(g, 2, sep, smtp_names[smtp_connection_had[i]]);
1778 sep = US",";
1779 }
1780
1781 if (!(s = string_from_gstring(g))) s = US"";
1782
1783 log_write(0, LOG_MAIN, "no MAIL in %sSMTP connection from %s D=%s%s",
1784 tcp_in_fastopen ? US"TFO " : US"",
1785 host_and_ident(FALSE), string_timesince(&smtp_connection_start), s);
1786 }
1787
1788
1789 /* Return list of recent smtp commands */
1790
1791 uschar *
1792 smtp_cmd_hist(void)
1793 {
1794 int i;
1795 gstring * list = NULL;
1796 uschar * s;
1797
1798 for (i = smtp_ch_index; i < SMTP_HBUFF_SIZE; i++)
1799 if (smtp_connection_had[i] != SCH_NONE)
1800 list = string_append_listele(list, ',', smtp_names[smtp_connection_had[i]]);
1801
1802 for (i = 0; i < smtp_ch_index; i++)
1803 list = string_append_listele(list, ',', smtp_names[smtp_connection_had[i]]);
1804
1805 s = string_from_gstring(list);
1806 return s ? s : US"";
1807 }
1808
1809
1810
1811
1812 /*************************************************
1813 * Check HELO line and set sender_helo_name *
1814 *************************************************/
1815
1816 /* Check the format of a HELO line. The data for HELO/EHLO is supposed to be
1817 the domain name of the sending host, or an ip literal in square brackets. The
1818 argument is placed in sender_helo_name, which is in malloc store, because it
1819 must persist over multiple incoming messages. If helo_accept_junk is set, this
1820 host is permitted to send any old junk (needed for some broken hosts).
1821 Otherwise, helo_allow_chars can be used for rogue characters in general
1822 (typically people want to let in underscores).
1823
1824 Argument:
1825 s the data portion of the line (already past any white space)
1826
1827 Returns: TRUE or FALSE
1828 */
1829
1830 static BOOL
1831 check_helo(uschar *s)
1832 {
1833 uschar *start = s;
1834 uschar *end = s + Ustrlen(s);
1835 BOOL yield = helo_accept_junk;
1836
1837 /* Discard any previous helo name */
1838
1839 if (sender_helo_name)
1840 {
1841 store_free(sender_helo_name);
1842 sender_helo_name = NULL;
1843 }
1844
1845 /* Skip tests if junk is permitted. */
1846
1847 if (!yield)
1848
1849 /* Allow the new standard form for IPv6 address literals, namely,
1850 [IPv6:....], and because someone is bound to use it, allow an equivalent
1851 IPv4 form. Allow plain addresses as well. */
1852
1853 if (*s == '[')
1854 {
1855 if (end[-1] == ']')
1856 {
1857 end[-1] = 0;
1858 if (strncmpic(s, US"[IPv6:", 6) == 0)
1859 yield = (string_is_ip_address(s+6, NULL) == 6);
1860 else if (strncmpic(s, US"[IPv4:", 6) == 0)
1861 yield = (string_is_ip_address(s+6, NULL) == 4);
1862 else
1863 yield = (string_is_ip_address(s+1, NULL) != 0);
1864 end[-1] = ']';
1865 }
1866 }
1867
1868 /* Non-literals must be alpha, dot, hyphen, plus any non-valid chars
1869 that have been configured (usually underscore - sigh). */
1870
1871 else if (*s)
1872 for (yield = TRUE; *s; s++)
1873 if (!isalnum(*s) && *s != '.' && *s != '-' &&
1874 Ustrchr(helo_allow_chars, *s) == NULL)
1875 {
1876 yield = FALSE;
1877 break;
1878 }
1879
1880 /* Save argument if OK */
1881
1882 if (yield) sender_helo_name = string_copy_malloc(start);
1883 return yield;
1884 }
1885
1886
1887
1888
1889
1890 /*************************************************
1891 * Extract SMTP command option *
1892 *************************************************/
1893
1894 /* This function picks the next option setting off the end of smtp_cmd_data. It
1895 is called for MAIL FROM and RCPT TO commands, to pick off the optional ESMTP
1896 things that can appear there.
1897
1898 Arguments:
1899 name point this at the name
1900 value point this at the data string
1901
1902 Returns: TRUE if found an option
1903 */
1904
1905 static BOOL
1906 extract_option(uschar **name, uschar **value)
1907 {
1908 uschar *n;
1909 uschar *v = smtp_cmd_data + Ustrlen(smtp_cmd_data) - 1;
1910 while (isspace(*v)) v--;
1911 v[1] = 0;
1912 while (v > smtp_cmd_data && *v != '=' && !isspace(*v))
1913 {
1914 /* Take care to not stop at a space embedded in a quoted local-part */
1915
1916 if (*v == '"') do v--; while (*v != '"' && v > smtp_cmd_data+1);
1917 v--;
1918 }
1919
1920 n = v;
1921 if (*v == '=')
1922 {
1923 while(isalpha(n[-1])) n--;
1924 /* RFC says SP, but TAB seen in wild and other major MTAs accept it */
1925 if (!isspace(n[-1])) return FALSE;
1926 n[-1] = 0;
1927 }
1928 else
1929 {
1930 n++;
1931 if (v == smtp_cmd_data) return FALSE;
1932 }
1933 *v++ = 0;
1934 *name = n;
1935 *value = v;
1936 return TRUE;
1937 }
1938
1939
1940
1941
1942
1943 /*************************************************
1944 * Reset for new message *
1945 *************************************************/
1946
1947 /* This function is called whenever the SMTP session is reset from
1948 within either of the setup functions; also from the daemon loop.
1949
1950 Argument: the stacking pool storage reset point
1951 Returns: nothing
1952 */
1953
1954 void
1955 smtp_reset(void *reset_point)
1956 {
1957 recipients_list = NULL;
1958 rcpt_count = rcpt_defer_count = rcpt_fail_count =
1959 raw_recipients_count = recipients_count = recipients_list_max = 0;
1960 message_linecount = 0;
1961 message_size = -1;
1962 acl_added_headers = NULL;
1963 acl_removed_headers = NULL;
1964 queue_only_policy = FALSE;
1965 rcpt_smtp_response = NULL;
1966 rcpt_smtp_response_same = TRUE;
1967 rcpt_in_progress = FALSE;
1968 deliver_freeze = FALSE; /* Can be set by ACL */
1969 freeze_tell = freeze_tell_config; /* Can be set by ACL */
1970 fake_response = OK; /* Can be set by ACL */
1971 #ifdef WITH_CONTENT_SCAN
1972 no_mbox_unspool = FALSE; /* Can be set by ACL */
1973 #endif
1974 submission_mode = FALSE; /* Can be set by ACL */
1975 suppress_local_fixups = suppress_local_fixups_default; /* Can be set by ACL */
1976 active_local_from_check = local_from_check; /* Can be set by ACL */
1977 active_local_sender_retain = local_sender_retain; /* Can be set by ACL */
1978 sending_ip_address = NULL;
1979 return_path = sender_address = NULL;
1980 sender_data = NULL; /* Can be set by ACL */
1981 deliver_localpart_parent = deliver_localpart_orig = NULL;
1982 deliver_domain_parent = deliver_domain_orig = NULL;
1983 callout_address = NULL;
1984 submission_name = NULL; /* Can be set by ACL */
1985 raw_sender = NULL; /* After SMTP rewrite, before qualifying */
1986 sender_address_unrewritten = NULL; /* Set only after verify rewrite */
1987 sender_verified_list = NULL; /* No senders verified */
1988 memset(sender_address_cache, 0, sizeof(sender_address_cache));
1989 memset(sender_domain_cache, 0, sizeof(sender_domain_cache));
1990
1991 authenticated_sender = NULL;
1992 #ifdef EXPERIMENTAL_BRIGHTMAIL
1993 bmi_run = 0;
1994 bmi_verdicts = NULL;
1995 #endif
1996 dnslist_domain = dnslist_matched = NULL;
1997 #ifndef DISABLE_DKIM
1998 dkim_cur_signer = dkim_signers =
1999 dkim_signing_domain = dkim_signing_selector = NULL;
2000 dkim_cur_signer = dkim_signers = dkim_signing_domain = dkim_signing_selector = NULL;
2001 dkim_disable_verify = dkim_collect_input = FALSE;
2002 dkim_verify_overall = dkim_verify_status = dkim_verify_reason = NULL;
2003 dkim_key_length = 0;
2004 dkim_verify_signers = US"$dkim_signers";
2005 #endif
2006 dsn_ret = 0;
2007 dsn_envid = NULL;
2008 deliver_host = deliver_host_address = NULL; /* Can be set by ACL */
2009 #ifndef DISABLE_PRDR
2010 prdr_requested = FALSE;
2011 #endif
2012 #ifdef SUPPORT_SPF
2013 spf_header_comment = spf_received = spf_result = spf_smtp_comment = NULL;
2014 spf_result_guessed = FALSE;
2015 #endif
2016 #ifdef EXPERIMENTAL_DMARC
2017 dmarc_has_been_checked = dmarc_disable_verify = dmarc_enable_forensic = FALSE;
2018 dmarc_domain_policy = dmarc_forensic_sender =
2019 dmarc_history_file = dmarc_status = dmarc_status_text =
2020 dmarc_used_domain = NULL;
2021 #endif
2022 #ifdef EXPERIMENTAL_ARC
2023 arc_state = arc_state_reason = NULL;
2024 #endif
2025 #ifdef SUPPORT_I18N
2026 message_smtputf8 = FALSE;
2027 #endif
2028 body_linecount = body_zerocount = 0;
2029
2030 sender_rate = sender_rate_limit = sender_rate_period = NULL;
2031 ratelimiters_mail = NULL; /* Updated by ratelimit ACL condition */
2032 /* Note that ratelimiters_conn persists across resets. */
2033
2034 /* Reset message ACL variables */
2035
2036 acl_var_m = NULL;
2037
2038 /* The message body variables use malloc store. They may be set if this is
2039 not the first message in an SMTP session and the previous message caused them
2040 to be referenced in an ACL. */
2041
2042 if (message_body)
2043 {
2044 store_free(message_body);
2045 message_body = NULL;
2046 }
2047
2048 if (message_body_end)
2049 {
2050 store_free(message_body_end);
2051 message_body_end = NULL;
2052 }
2053
2054 /* Warning log messages are also saved in malloc store. They are saved to avoid
2055 repetition in the same message, but it seems right to repeat them for different
2056 messages. */
2057
2058 while (acl_warn_logged)
2059 {
2060 string_item *this = acl_warn_logged;
2061 acl_warn_logged = acl_warn_logged->next;
2062 store_free(this);
2063 }
2064 store_reset(reset_point);
2065 }
2066
2067
2068
2069
2070
2071 /*************************************************
2072 * Initialize for incoming batched SMTP message *
2073 *************************************************/
2074
2075 /* This function is called from smtp_setup_msg() in the case when
2076 smtp_batched_input is true. This happens when -bS is used to pass a whole batch
2077 of messages in one file with SMTP commands between them. All errors must be
2078 reported by sending a message, and only MAIL FROM, RCPT TO, and DATA are
2079 relevant. After an error on a sender, or an invalid recipient, the remainder
2080 of the message is skipped. The value of received_protocol is already set.
2081
2082 Argument: none
2083 Returns: > 0 message successfully started (reached DATA)
2084 = 0 QUIT read or end of file reached
2085 < 0 should not occur
2086 */
2087
2088 static int
2089 smtp_setup_batch_msg(void)
2090 {
2091 int done = 0;
2092 void *reset_point = store_get(0);
2093
2094 /* Save the line count at the start of each transaction - single commands
2095 like HELO and RSET count as whole transactions. */
2096
2097 bsmtp_transaction_linecount = receive_linecount;
2098
2099 if ((receive_feof)()) return 0; /* Treat EOF as QUIT */
2100
2101 cancel_cutthrough_connection(TRUE, US"smtp_setup_batch_msg");
2102 smtp_reset(reset_point); /* Reset for start of message */
2103
2104 /* Deal with SMTP commands. This loop is exited by setting done to a POSITIVE
2105 value. The values are 2 larger than the required yield of the function. */
2106
2107 while (done <= 0)
2108 {
2109 uschar *errmess;
2110 uschar *recipient = NULL;
2111 int start, end, sender_domain, recipient_domain;
2112
2113 switch(smtp_read_command(FALSE, GETC_BUFFER_UNLIMITED))
2114 {
2115 /* The HELO/EHLO commands set sender_address_helo if they have
2116 valid data; otherwise they are ignored, except that they do
2117 a reset of the state. */
2118
2119 case HELO_CMD:
2120 case EHLO_CMD:
2121
2122 check_helo(smtp_cmd_data);
2123 /* Fall through */
2124
2125 case RSET_CMD:
2126 cancel_cutthrough_connection(TRUE, US"RSET received");
2127 smtp_reset(reset_point);
2128 bsmtp_transaction_linecount = receive_linecount;
2129 break;
2130
2131
2132 /* The MAIL FROM command requires an address as an operand. All we
2133 do here is to parse it for syntactic correctness. The form "<>" is
2134 a special case which converts into an empty string. The start/end
2135 pointers in the original are not used further for this address, as
2136 it is the canonical extracted address which is all that is kept. */
2137
2138 case MAIL_CMD:
2139 smtp_mailcmd_count++; /* Count for no-mail log */
2140 if (sender_address != NULL)
2141 /* The function moan_smtp_batch() does not return. */
2142 moan_smtp_batch(smtp_cmd_buffer, "503 Sender already given");
2143
2144 if (smtp_cmd_data[0] == 0)
2145 /* The function moan_smtp_batch() does not return. */
2146 moan_smtp_batch(smtp_cmd_buffer, "501 MAIL FROM must have an address operand");
2147
2148 /* Reset to start of message */
2149
2150 cancel_cutthrough_connection(TRUE, US"MAIL received");
2151 smtp_reset(reset_point);
2152
2153 /* Apply SMTP rewrite */
2154
2155 raw_sender = ((rewrite_existflags & rewrite_smtp) != 0)?
2156 rewrite_one(smtp_cmd_data, rewrite_smtp|rewrite_smtp_sender, NULL, FALSE,
2157 US"", global_rewrite_rules) : smtp_cmd_data;
2158
2159 /* Extract the address; the TRUE flag allows <> as valid */
2160
2161 raw_sender =
2162 parse_extract_address(raw_sender, &errmess, &start, &end, &sender_domain,
2163 TRUE);
2164
2165 if (!raw_sender)
2166 /* The function moan_smtp_batch() does not return. */
2167 moan_smtp_batch(smtp_cmd_buffer, "501 %s", errmess);
2168
2169 sender_address = string_copy(raw_sender);
2170
2171 /* Qualify unqualified sender addresses if permitted to do so. */
2172
2173 if ( !sender_domain
2174 && sender_address[0] != 0 && sender_address[0] != '@')
2175 if (allow_unqualified_sender)
2176 {
2177 sender_address = rewrite_address_qualify(sender_address, FALSE);
2178 DEBUG(D_receive) debug_printf("unqualified address %s accepted "
2179 "and rewritten\n", raw_sender);
2180 }
2181 /* The function moan_smtp_batch() does not return. */
2182 else
2183 moan_smtp_batch(smtp_cmd_buffer, "501 sender address must contain "
2184 "a domain");
2185 break;
2186
2187
2188 /* The RCPT TO command requires an address as an operand. All we do
2189 here is to parse it for syntactic correctness. There may be any number
2190 of RCPT TO commands, specifying multiple senders. We build them all into
2191 a data structure that is in argc/argv format. The start/end values
2192 given by parse_extract_address are not used, as we keep only the
2193 extracted address. */
2194
2195 case RCPT_CMD:
2196 if (!sender_address)
2197 /* The function moan_smtp_batch() does not return. */
2198 moan_smtp_batch(smtp_cmd_buffer, "503 No sender yet given");
2199
2200 if (smtp_cmd_data[0] == 0)
2201 /* The function moan_smtp_batch() does not return. */
2202 moan_smtp_batch(smtp_cmd_buffer,
2203 "501 RCPT TO must have an address operand");
2204
2205 /* Check maximum number allowed */
2206
2207 if (recipients_max > 0 && recipients_count + 1 > recipients_max)
2208 /* The function moan_smtp_batch() does not return. */
2209 moan_smtp_batch(smtp_cmd_buffer, "%s too many recipients",
2210 recipients_max_reject? "552": "452");
2211
2212 /* Apply SMTP rewrite, then extract address. Don't allow "<>" as a
2213 recipient address */
2214
2215 recipient = rewrite_existflags & rewrite_smtp
2216 ? rewrite_one(smtp_cmd_data, rewrite_smtp, NULL, FALSE, US"",
2217 global_rewrite_rules)
2218 : smtp_cmd_data;
2219
2220 recipient = parse_extract_address(recipient, &errmess, &start, &end,
2221 &recipient_domain, FALSE);
2222
2223 if (!recipient)
2224 /* The function moan_smtp_batch() does not return. */
2225 moan_smtp_batch(smtp_cmd_buffer, "501 %s", errmess);
2226
2227 /* If the recipient address is unqualified, qualify it if permitted. Then
2228 add it to the list of recipients. */
2229
2230 if (!recipient_domain)
2231 if (allow_unqualified_recipient)
2232 {
2233 DEBUG(D_receive) debug_printf("unqualified address %s accepted\n",
2234 recipient);
2235 recipient = rewrite_address_qualify(recipient, TRUE);
2236 }
2237 /* The function moan_smtp_batch() does not return. */
2238 else
2239 moan_smtp_batch(smtp_cmd_buffer,
2240 "501 recipient address must contain a domain");
2241
2242 receive_add_recipient(recipient, -1);
2243 break;
2244
2245
2246 /* The DATA command is legal only if it follows successful MAIL FROM
2247 and RCPT TO commands. This function is complete when a valid DATA
2248 command is encountered. */
2249
2250 case DATA_CMD:
2251 if (!sender_address || recipients_count <= 0)
2252 /* The function moan_smtp_batch() does not return. */
2253 if (!sender_address)
2254 moan_smtp_batch(smtp_cmd_buffer,
2255 "503 MAIL FROM:<sender> command must precede DATA");
2256 else
2257 moan_smtp_batch(smtp_cmd_buffer,
2258 "503 RCPT TO:<recipient> must precede DATA");
2259 else
2260 {
2261 done = 3; /* DATA successfully achieved */
2262 message_ended = END_NOTENDED; /* Indicate in middle of message */
2263 }
2264 break;
2265
2266
2267 /* The VRFY, EXPN, HELP, ETRN, and NOOP commands are ignored. */
2268
2269 case VRFY_CMD:
2270 case EXPN_CMD:
2271 case HELP_CMD:
2272 case NOOP_CMD:
2273 case ETRN_CMD:
2274 bsmtp_transaction_linecount = receive_linecount;
2275 break;
2276
2277
2278 case EOF_CMD:
2279 case QUIT_CMD:
2280 done = 2;
2281 break;
2282
2283
2284 case BADARG_CMD:
2285 /* The function moan_smtp_batch() does not return. */
2286 moan_smtp_batch(smtp_cmd_buffer, "501 Unexpected argument data");
2287 break;
2288
2289
2290 case BADCHAR_CMD:
2291 /* The function moan_smtp_batch() does not return. */
2292 moan_smtp_batch(smtp_cmd_buffer, "501 Unexpected NULL in SMTP command");
2293 break;
2294
2295
2296 default:
2297 /* The function moan_smtp_batch() does not return. */
2298 moan_smtp_batch(smtp_cmd_buffer, "500 Command unrecognized");
2299 break;
2300 }
2301 }
2302
2303 return done - 2; /* Convert yield values */
2304 }
2305
2306
2307
2308
2309 static BOOL
2310 smtp_log_tls_fail(uschar * errstr)
2311 {
2312 uschar * conn_info = smtp_get_connection_info();
2313
2314 if (Ustrncmp(conn_info, US"SMTP ", 5) == 0) conn_info += 5;
2315 /* I'd like to get separated H= here, but too hard for now */
2316
2317 log_write(0, LOG_MAIN, "TLS error on %s %s", conn_info, errstr);
2318 return FALSE;
2319 }
2320
2321
2322
2323
2324 #ifdef TCP_FASTOPEN
2325 static void
2326 tfo_in_check(void)
2327 {
2328 # ifdef TCP_INFO
2329 struct tcp_info tinfo;
2330 socklen_t len = sizeof(tinfo);
2331
2332 if ( getsockopt(fileno(smtp_out), IPPROTO_TCP, TCP_INFO, &tinfo, &len) == 0
2333 && tinfo.tcpi_state == TCP_SYN_RECV
2334 )
2335 {
2336 DEBUG(D_receive) debug_printf("TCP_FASTOPEN mode connection (state TCP_SYN_RECV)\n");
2337 tcp_in_fastopen = TRUE;
2338 }
2339 # endif
2340 }
2341 #endif
2342
2343
2344 /*************************************************
2345 * Start an SMTP session *
2346 *************************************************/
2347
2348 /* This function is called at the start of an SMTP session. Thereafter,
2349 smtp_setup_msg() is called to initiate each separate message. This
2350 function does host-specific testing, and outputs the banner line.
2351
2352 Arguments: none
2353 Returns: FALSE if the session can not continue; something has
2354 gone wrong, or the connection to the host is blocked
2355 */
2356
2357 BOOL
2358 smtp_start_session(void)
2359 {
2360 int esclen;
2361 uschar *user_msg, *log_msg;
2362 uschar *code, *esc;
2363 uschar *p, *s;
2364 gstring * ss;
2365
2366 gettimeofday(&smtp_connection_start, NULL);
2367 for (smtp_ch_index = 0; smtp_ch_index < SMTP_HBUFF_SIZE; smtp_ch_index++)
2368 smtp_connection_had[smtp_ch_index] = SCH_NONE;
2369 smtp_ch_index = 0;
2370
2371 /* Default values for certain variables */
2372
2373 helo_seen = esmtp = helo_accept_junk = FALSE;
2374 smtp_mailcmd_count = 0;
2375 count_nonmail = TRUE_UNSET;
2376 synprot_error_count = unknown_command_count = nonmail_command_count = 0;
2377 smtp_delay_mail = smtp_rlm_base;
2378 auth_advertised = FALSE;
2379 pipelining_advertised = FALSE;
2380 pipelining_enable = TRUE;
2381 sync_cmd_limit = NON_SYNC_CMD_NON_PIPELINING;
2382 smtp_exit_function_called = FALSE; /* For avoiding loop in not-quit exit */
2383
2384 /* If receiving by -bs from a trusted user, or testing with -bh, we allow
2385 authentication settings from -oMaa to remain in force. */
2386
2387 if (!host_checking && !sender_host_notsocket)
2388 sender_host_auth_pubname = sender_host_authenticated = NULL;
2389 authenticated_by = NULL;
2390
2391 #ifdef SUPPORT_TLS
2392 tls_in.cipher = tls_in.peerdn = NULL;
2393 tls_in.ourcert = tls_in.peercert = NULL;
2394 tls_in.sni = NULL;
2395 tls_in.ocsp = OCSP_NOT_REQ;
2396 tls_advertised = FALSE;
2397 #endif
2398 dsn_advertised = FALSE;
2399 #ifdef SUPPORT_I18N
2400 smtputf8_advertised = FALSE;
2401 #endif
2402
2403 /* Reset ACL connection variables */
2404
2405 acl_var_c = NULL;
2406
2407 /* Allow for trailing 0 in the command and data buffers. */
2408
2409 if (!(smtp_cmd_buffer = US malloc(2*SMTP_CMD_BUFFER_SIZE + 2)))
2410 log_write(0, LOG_MAIN|LOG_PANIC_DIE,
2411 "malloc() failed for SMTP command buffer");
2412
2413 smtp_cmd_buffer[0] = 0;
2414 smtp_data_buffer = smtp_cmd_buffer + SMTP_CMD_BUFFER_SIZE + 1;
2415
2416 /* For batched input, the protocol setting can be overridden from the
2417 command line by a trusted caller. */
2418
2419 if (smtp_batched_input)
2420 {
2421 if (!received_protocol) received_protocol = US"local-bsmtp";
2422 }
2423
2424 /* For non-batched SMTP input, the protocol setting is forced here. It will be
2425 reset later if any of EHLO/AUTH/STARTTLS are received. */
2426
2427 else
2428 received_protocol =
2429 (sender_host_address ? protocols : protocols_local) [pnormal];
2430
2431 /* Set up the buffer for inputting using direct read() calls, and arrange to
2432 call the local functions instead of the standard C ones. Place a NUL at the
2433 end of the buffer to safety-stop C-string reads from it. */
2434
2435 if (!(smtp_inbuffer = US malloc(IN_BUFFER_SIZE)))
2436 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "malloc() failed for SMTP input buffer");
2437 smtp_inbuffer[IN_BUFFER_SIZE-1] = '\0';
2438
2439 receive_getc = smtp_getc;
2440 receive_getbuf = smtp_getbuf;
2441 receive_get_cache = smtp_get_cache;
2442 receive_ungetc = smtp_ungetc;
2443 receive_feof = smtp_feof;
2444 receive_ferror = smtp_ferror;
2445 receive_smtp_buffered = smtp_buffered;
2446 smtp_inptr = smtp_inend = smtp_inbuffer;
2447 smtp_had_eof = smtp_had_error = 0;
2448
2449 /* Set up the message size limit; this may be host-specific */
2450
2451 thismessage_size_limit = expand_string_integer(message_size_limit, TRUE);
2452 if (expand_string_message)
2453 {
2454 if (thismessage_size_limit == -1)
2455 log_write(0, LOG_MAIN|LOG_PANIC, "unable to expand message_size_limit: "
2456 "%s", expand_string_message);
2457 else
2458 log_write(0, LOG_MAIN|LOG_PANIC, "invalid message_size_limit: "
2459 "%s", expand_string_message);
2460 smtp_closedown(US"Temporary local problem - please try later");
2461 return FALSE;
2462 }
2463
2464 /* When a message is input locally via the -bs or -bS options, sender_host_
2465 unknown is set unless -oMa was used to force an IP address, in which case it
2466 is checked like a real remote connection. When -bs is used from inetd, this
2467 flag is not set, causing the sending host to be checked. The code that deals
2468 with IP source routing (if configured) is never required for -bs or -bS and
2469 the flag sender_host_notsocket is used to suppress it.
2470
2471 If smtp_accept_max and smtp_accept_reserve are set, keep some connections in
2472 reserve for certain hosts and/or networks. */
2473
2474 if (!sender_host_unknown)
2475 {
2476 int rc;
2477 BOOL reserved_host = FALSE;
2478
2479 /* Look up IP options (source routing info) on the socket if this is not an
2480 -oMa "host", and if any are found, log them and drop the connection.
2481
2482 Linux (and others now, see below) is different to everyone else, so there
2483 has to be some conditional compilation here. Versions of Linux before 2.1.15
2484 used a structure whose name was "options". Somebody finally realized that
2485 this name was silly, and it got changed to "ip_options". I use the
2486 newer name here, but there is a fudge in the script that sets up os.h
2487 to define a macro in older Linux systems.
2488
2489 Sigh. Linux is a fast-moving target. Another generation of Linux uses
2490 glibc 2, which has chosen ip_opts for the structure name. This is now
2491 really a glibc thing rather than a Linux thing, so the condition name
2492 has been changed to reflect this. It is relevant also to GNU/Hurd.
2493
2494 Mac OS 10.x (Darwin) is like the later glibc versions, but without the
2495 setting of the __GLIBC__ macro, so we can't detect it automatically. There's
2496 a special macro defined in the os.h file.
2497
2498 Some DGUX versions on older hardware appear not to support IP options at
2499 all, so there is now a general macro which can be set to cut out this
2500 support altogether.
2501
2502 How to do this properly in IPv6 is not yet known. */
2503
2504 #if !HAVE_IPV6 && !defined(NO_IP_OPTIONS)
2505
2506 #ifdef GLIBC_IP_OPTIONS
2507 #if (!defined __GLIBC__) || (__GLIBC__ < 2)
2508 #define OPTSTYLE 1
2509 #else
2510 #define OPTSTYLE 2
2511 #endif
2512 #elif defined DARWIN_IP_OPTIONS
2513 #define OPTSTYLE 2
2514 #else
2515 #define OPTSTYLE 3
2516 #endif
2517
2518 if (!host_checking && !sender_host_notsocket)
2519 {
2520 #if OPTSTYLE == 1
2521 EXIM_SOCKLEN_T optlen = sizeof(struct ip_options) + MAX_IPOPTLEN;
2522 struct ip_options *ipopt = store_get(optlen);
2523 #elif OPTSTYLE == 2
2524 struct ip_opts ipoptblock;
2525 struct ip_opts *ipopt = &ipoptblock;
2526 EXIM_SOCKLEN_T optlen = sizeof(ipoptblock);
2527 #else
2528 struct ipoption ipoptblock;
2529 struct ipoption *ipopt = &ipoptblock;
2530 EXIM_SOCKLEN_T optlen = sizeof(ipoptblock);
2531 #endif
2532
2533 /* Occasional genuine failures of getsockopt() have been seen - for
2534 example, "reset by peer". Therefore, just log and give up on this
2535 call, unless the error is ENOPROTOOPT. This error is given by systems
2536 that have the interfaces but not the mechanism - e.g. GNU/Hurd at the time
2537 of writing. So for that error, carry on - we just can't do an IP options
2538 check. */
2539
2540 DEBUG(D_receive) debug_printf("checking for IP options\n");
2541
2542 if (getsockopt(fileno(smtp_out), IPPROTO_IP, IP_OPTIONS, US (ipopt),
2543 &optlen) < 0)
2544 {
2545 if (errno != ENOPROTOOPT)
2546 {
2547 log_write(0, LOG_MAIN, "getsockopt() failed from %s: %s",
2548 host_and_ident(FALSE), strerror(errno));
2549 smtp_printf("451 SMTP service not available\r\n", FALSE);
2550 return FALSE;
2551 }
2552 }
2553
2554 /* Deal with any IP options that are set. On the systems I have looked at,
2555 the value of MAX_IPOPTLEN has been 40, meaning that there should never be
2556 more logging data than will fit in big_buffer. Nevertheless, after somebody
2557 questioned this code, I've added in some paranoid checking. */
2558
2559 else if (optlen > 0)
2560 {
2561 uschar *p = big_buffer;
2562 uschar *pend = big_buffer + big_buffer_size;
2563 uschar *opt, *adptr;
2564 int optcount;
2565 struct in_addr addr;
2566
2567 #if OPTSTYLE == 1
2568 uschar *optstart = US (ipopt->__data);
2569 #elif OPTSTYLE == 2
2570 uschar *optstart = US (ipopt->ip_opts);
2571 #else
2572 uschar *optstart = US (ipopt->ipopt_list);
2573 #endif
2574
2575 DEBUG(D_receive) debug_printf("IP options exist\n");
2576
2577 Ustrcpy(p, "IP options on incoming call:");
2578 p += Ustrlen(p);
2579
2580 for (opt = optstart; opt != NULL &&
2581 opt < US (ipopt) + optlen;)
2582 {
2583 switch (*opt)
2584 {
2585 case IPOPT_EOL:
2586 opt = NULL;
2587 break;
2588
2589 case IPOPT_NOP:
2590 opt++;
2591 break;
2592
2593 case IPOPT_SSRR:
2594 case IPOPT_LSRR:
2595 if (!string_format(p, pend-p, " %s [@%s",
2596 (*opt == IPOPT_SSRR)? "SSRR" : "LSRR",
2597 #if OPTSTYLE == 1
2598 inet_ntoa(*((struct in_addr *)(&(ipopt->faddr))))))
2599 #elif OPTSTYLE == 2
2600 inet_ntoa(ipopt->ip_dst)))
2601 #else
2602 inet_ntoa(ipopt->ipopt_dst)))
2603 #endif
2604 {
2605 opt = NULL;
2606 break;
2607 }
2608
2609 p += Ustrlen(p);
2610 optcount = (opt[1] - 3) / sizeof(struct in_addr);
2611 adptr = opt + 3;
2612 while (optcount-- > 0)
2613 {
2614 memcpy(&addr, adptr, sizeof(addr));
2615 if (!string_format(p, pend - p - 1, "%s%s",
2616 (optcount == 0)? ":" : "@", inet_ntoa(addr)))
2617 {
2618 opt = NULL;
2619 break;
2620 }
2621 p += Ustrlen(p);
2622 adptr += sizeof(struct in_addr);
2623 }
2624 *p++ = ']';
2625 opt += opt[1];
2626 break;
2627
2628 default:
2629 {
2630 int i;
2631 if (pend - p < 4 + 3*opt[1]) { opt = NULL; break; }
2632 Ustrcat(p, "[ ");
2633 p += 2;
2634 for (i = 0; i < opt[1]; i++)
2635 p += sprintf(CS p, "%2.2x ", opt[i]);
2636 *p++ = ']';
2637 }
2638 opt += opt[1];
2639 break;
2640 }
2641 }
2642
2643 *p = 0;
2644 log_write(0, LOG_MAIN, "%s", big_buffer);
2645
2646 /* Refuse any call with IP options. This is what tcpwrappers 7.5 does. */
2647
2648 log_write(0, LOG_MAIN|LOG_REJECT,
2649 "connection from %s refused (IP options)", host_and_ident(FALSE));
2650
2651 smtp_printf("554 SMTP service not available\r\n", FALSE);
2652 return FALSE;
2653 }
2654
2655 /* Length of options = 0 => there are no options */
2656
2657 else DEBUG(D_receive) debug_printf("no IP options found\n");
2658 }
2659 #endif /* HAVE_IPV6 && !defined(NO_IP_OPTIONS) */
2660
2661 /* Set keep-alive in socket options. The option is on by default. This
2662 setting is an attempt to get rid of some hanging connections that stick in
2663 read() when the remote end (usually a dialup) goes away. */
2664
2665 if (smtp_accept_keepalive && !sender_host_notsocket)
2666 ip_keepalive(fileno(smtp_out), sender_host_address, FALSE);
2667
2668 /* If the current host matches host_lookup, set the name by doing a
2669 reverse lookup. On failure, sender_host_name will be NULL and
2670 host_lookup_failed will be TRUE. This may or may not be serious - optional
2671 checks later. */
2672
2673 if (verify_check_host(&host_lookup) == OK)
2674 {
2675 (void)host_name_lookup();
2676 host_build_sender_fullhost();
2677 }
2678
2679 /* Delay this until we have the full name, if it is looked up. */
2680
2681 set_process_info("handling incoming connection from %s",
2682 host_and_ident(FALSE));
2683
2684 /* Expand smtp_receive_timeout, if needed */
2685
2686 if (smtp_receive_timeout_s)
2687 {
2688 uschar * exp;
2689 if ( !(exp = expand_string(smtp_receive_timeout_s))
2690 || !(*exp)
2691 || (smtp_receive_timeout = readconf_readtime(exp, 0, FALSE)) < 0
2692 )
2693 log_write(0, LOG_MAIN|LOG_PANIC,
2694 "bad value for smtp_receive_timeout: '%s'", exp ? exp : US"");
2695 }
2696
2697 /* Test for explicit connection rejection */
2698
2699 if (verify_check_host(&host_reject_connection) == OK)
2700 {
2701 log_write(L_connection_reject, LOG_MAIN|LOG_REJECT, "refused connection "
2702 "from %s (host_reject_connection)", host_and_ident(FALSE));
2703 smtp_printf("554 SMTP service not available\r\n", FALSE);
2704 return FALSE;
2705 }
2706
2707 /* Test with TCP Wrappers if so configured. There is a problem in that
2708 hosts_ctl() returns 0 (deny) under a number of system failure circumstances,
2709 such as disks dying. In these cases, it is desirable to reject with a 4xx
2710 error instead of a 5xx error. There isn't a "right" way to detect such
2711 problems. The following kludge is used: errno is zeroed before calling
2712 hosts_ctl(). If the result is "reject", a 5xx error is given only if the
2713 value of errno is 0 or ENOENT (which happens if /etc/hosts.{allow,deny} does
2714 not exist). */
2715
2716 #ifdef USE_TCP_WRAPPERS
2717 errno = 0;
2718 if (!(tcp_wrappers_name = expand_string(tcp_wrappers_daemon_name)))
2719 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "Expansion of \"%s\" "
2720 "(tcp_wrappers_name) failed: %s", string_printing(tcp_wrappers_name),
2721 expand_string_message);
2722
2723 if (!hosts_ctl(tcp_wrappers_name,
2724 sender_host_name ? CS sender_host_name : STRING_UNKNOWN,
2725 sender_host_address ? CS sender_host_address : STRING_UNKNOWN,
2726 sender_ident ? CS sender_ident : STRING_UNKNOWN))
2727 {
2728 if (errno == 0 || errno == ENOENT)
2729 {
2730 HDEBUG(D_receive) debug_printf("tcp wrappers rejection\n");
2731 log_write(L_connection_reject,
2732 LOG_MAIN|LOG_REJECT, "refused connection from %s "
2733 "(tcp wrappers)", host_and_ident(FALSE));
2734 smtp_printf("554 SMTP service not available\r\n", FALSE);
2735 }
2736 else
2737 {
2738 int save_errno = errno;
2739 HDEBUG(D_receive) debug_printf("tcp wrappers rejected with unexpected "
2740 "errno value %d\n", save_errno);
2741 log_write(L_connection_reject,
2742 LOG_MAIN|LOG_REJECT, "temporarily refused connection from %s "
2743 "(tcp wrappers errno=%d)", host_and_ident(FALSE), save_errno);
2744 smtp_printf("451 Temporary local problem - please try later\r\n", FALSE);
2745 }
2746 return FALSE;
2747 }
2748 #endif
2749
2750 /* Check for reserved slots. The value of smtp_accept_count has already been
2751 incremented to include this process. */
2752
2753 if (smtp_accept_max > 0 &&
2754 smtp_accept_count > smtp_accept_max - smtp_accept_reserve)
2755 {
2756 if ((rc = verify_check_host(&smtp_reserve_hosts)) != OK)
2757 {
2758 log_write(L_connection_reject,
2759 LOG_MAIN, "temporarily refused connection from %s: not in "
2760 "reserve list: connected=%d max=%d reserve=%d%s",
2761 host_and_ident(FALSE), smtp_accept_count - 1, smtp_accept_max,
2762 smtp_accept_reserve, (rc == DEFER)? " (lookup deferred)" : "");
2763 smtp_printf("421 %s: Too many concurrent SMTP connections; "
2764 "please try again later\r\n", FALSE, smtp_active_hostname);
2765 return FALSE;
2766 }
2767 reserved_host = TRUE;
2768 }
2769
2770 /* If a load level above which only messages from reserved hosts are
2771 accepted is set, check the load. For incoming calls via the daemon, the
2772 check is done in the superior process if there are no reserved hosts, to
2773 save a fork. In all cases, the load average will already be available
2774 in a global variable at this point. */
2775
2776 if (smtp_load_reserve >= 0 &&
2777 load_average > smtp_load_reserve &&
2778 !reserved_host &&
2779 verify_check_host(&smtp_reserve_hosts) != OK)
2780 {
2781 log_write(L_connection_reject,
2782 LOG_MAIN, "temporarily refused connection from %s: not in "
2783 "reserve list and load average = %.2f", host_and_ident(FALSE),
2784 (double)load_average/1000.0);
2785 smtp_printf("421 %s: Too much load; please try again later\r\n", FALSE,
2786 smtp_active_hostname);
2787 return FALSE;
2788 }
2789
2790 /* Determine whether unqualified senders or recipients are permitted
2791 for this host. Unfortunately, we have to do this every time, in order to
2792 set the flags so that they can be inspected when considering qualifying
2793 addresses in the headers. For a site that permits no qualification, this
2794 won't take long, however. */
2795
2796 allow_unqualified_sender =
2797 verify_check_host(&sender_unqualified_hosts) == OK;
2798
2799 allow_unqualified_recipient =
2800 verify_check_host(&recipient_unqualified_hosts) == OK;
2801
2802 /* Determine whether HELO/EHLO is required for this host. The requirement
2803 can be hard or soft. */
2804
2805 helo_required = verify_check_host(&helo_verify_hosts) == OK;
2806 if (!helo_required)
2807 helo_verify = verify_check_host(&helo_try_verify_hosts) == OK;
2808
2809 /* Determine whether this hosts is permitted to send syntactic junk
2810 after a HELO or EHLO command. */
2811
2812 helo_accept_junk = verify_check_host(&helo_accept_junk_hosts) == OK;
2813 }
2814
2815 /* For batch SMTP input we are now done. */
2816
2817 if (smtp_batched_input) return TRUE;
2818
2819 /* If valid Proxy Protocol source is connecting, set up session.
2820 * Failure will not allow any SMTP function other than QUIT. */
2821
2822 #ifdef SUPPORT_PROXY
2823 proxy_session = FALSE;
2824 proxy_session_failed = FALSE;
2825 if (check_proxy_protocol_host())
2826 setup_proxy_protocol_host();
2827 #endif
2828
2829 /* Start up TLS if tls_on_connect is set. This is for supporting the legacy
2830 smtps port for use with older style SSL MTAs. */
2831
2832 #ifdef SUPPORT_TLS
2833 if (tls_in.on_connect)
2834 {
2835 if (tls_server_start(tls_require_ciphers, &user_msg) != OK)
2836 return smtp_log_tls_fail(user_msg);
2837 cmd_list[CMD_LIST_TLS_AUTH].is_mail_cmd = TRUE;
2838 }
2839 #endif
2840
2841 /* Run the connect ACL if it exists */
2842
2843 user_msg = NULL;
2844 if (acl_smtp_connect)
2845 {
2846 int rc;
2847 if ((rc = acl_check(ACL_WHERE_CONNECT, NULL, acl_smtp_connect, &user_msg,
2848 &log_msg)) != OK)
2849 {
2850 (void) smtp_handle_acl_fail(ACL_WHERE_CONNECT, rc, user_msg, log_msg);
2851 return FALSE;
2852 }
2853 }
2854
2855 /* Output the initial message for a two-way SMTP connection. It may contain
2856 newlines, which then cause a multi-line response to be given. */
2857
2858 code = US"220"; /* Default status code */
2859 esc = US""; /* Default extended status code */
2860 esclen = 0; /* Length of esc */
2861
2862 if (!user_msg)
2863 {
2864 if (!(s = expand_string(smtp_banner)))
2865 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "Expansion of \"%s\" (smtp_banner) "
2866 "failed: %s", smtp_banner, expand_string_message);
2867 }
2868 else
2869 {
2870 int codelen = 3;
2871 s = user_msg;
2872 smtp_message_code(&code, &codelen, &s, NULL, TRUE);
2873 if (codelen > 4)
2874 {
2875 esc = code + 4;
2876 esclen = codelen - 4;
2877 }
2878 }
2879
2880 /* Remove any terminating newlines; might as well remove trailing space too */
2881
2882 p = s + Ustrlen(s);
2883 while (p > s && isspace(p[-1])) p--;
2884 *p = 0;
2885
2886 /* It seems that CC:Mail is braindead, and assumes that the greeting message
2887 is all contained in a single IP packet. The original code wrote out the
2888 greeting using several calls to fprint/fputc, and on busy servers this could
2889 cause it to be split over more than one packet - which caused CC:Mail to fall
2890 over when it got the second part of the greeting after sending its first
2891 command. Sigh. To try to avoid this, build the complete greeting message
2892 first, and output it in one fell swoop. This gives a better chance of it
2893 ending up as a single packet. */
2894
2895 ss = string_get(256);
2896
2897 p = s;
2898 do /* At least once, in case we have an empty string */
2899 {
2900 int len;
2901 uschar *linebreak = Ustrchr(p, '\n');
2902 ss = string_catn(ss, code, 3);
2903 if (!linebreak)
2904 {
2905 len = Ustrlen(p);
2906 ss = string_catn(ss, US" ", 1);
2907 }
2908 else
2909 {
2910 len = linebreak - p;
2911 ss = string_catn(ss, US"-", 1);
2912 }
2913 ss = string_catn(ss, esc, esclen);
2914 ss = string_catn(ss, p, len);
2915 ss = string_catn(ss, US"\r\n", 2);
2916 p += len;
2917 if (linebreak) p++;
2918 }
2919 while (*p);
2920
2921 /* Before we write the banner, check that there is no input pending, unless
2922 this synchronisation check is disabled. */
2923
2924 if (!check_sync())
2925 {
2926 unsigned n = smtp_inend - smtp_inptr;
2927 if (n > 32) n = 32;
2928
2929 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP protocol "
2930 "synchronization error (input sent without waiting for greeting): "
2931 "rejected connection from %s input=\"%s\"", host_and_ident(TRUE),
2932 string_printing(string_copyn(smtp_inptr, n)));
2933 smtp_printf("554 SMTP synchronization error\r\n", FALSE);
2934 return FALSE;
2935 }
2936
2937 /* Now output the banner */
2938
2939 smtp_printf("%s", FALSE, string_from_gstring(ss));
2940
2941 /* Attempt to see if we sent the banner before the last ACK of the 3-way
2942 handshake arrived. If so we must have managed a TFO. */
2943
2944 #ifdef TCP_FASTOPEN
2945 tfo_in_check();
2946 #endif
2947
2948 return TRUE;
2949 }
2950
2951
2952
2953
2954
2955 /*************************************************
2956 * Handle SMTP syntax and protocol errors *
2957 *************************************************/
2958
2959 /* Write to the log for SMTP syntax errors in incoming commands, if configured
2960 to do so. Then transmit the error response. The return value depends on the
2961 number of syntax and protocol errors in this SMTP session.
2962
2963 Arguments:
2964 type error type, given as a log flag bit
2965 code response code; <= 0 means don't send a response
2966 data data to reflect in the response (can be NULL)
2967 errmess the error message
2968
2969 Returns: -1 limit of syntax/protocol errors NOT exceeded
2970 +1 limit of syntax/protocol errors IS exceeded
2971
2972 These values fit in with the values of the "done" variable in the main
2973 processing loop in smtp_setup_msg(). */
2974
2975 static int
2976 synprot_error(int type, int code, uschar *data, uschar *errmess)
2977 {
2978 int yield = -1;
2979
2980 log_write(type, LOG_MAIN, "SMTP %s error in \"%s\" %s %s",
2981 (type == L_smtp_syntax_error)? "syntax" : "protocol",
2982 string_printing(smtp_cmd_buffer), host_and_ident(TRUE), errmess);
2983
2984 if (++synprot_error_count > smtp_max_synprot_errors)
2985 {
2986 yield = 1;
2987 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
2988 "syntax or protocol errors (last command was \"%s\")",
2989 host_and_ident(FALSE), string_printing(smtp_cmd_buffer));
2990 }
2991
2992 if (code > 0)
2993 {
2994 smtp_printf("%d%c%s%s%s\r\n", FALSE, code, yield == 1 ? '-' : ' ',
2995 data ? data : US"", data ? US": " : US"", errmess);
2996 if (yield == 1)
2997 smtp_printf("%d Too many syntax or protocol errors\r\n", FALSE, code);
2998 }
2999
3000 return yield;
3001 }
3002
3003
3004
3005
3006 /*************************************************
3007 * Send SMTP response, possibly multiline *
3008 *************************************************/
3009
3010 /* There are, it seems, broken clients out there that cannot handle multiline
3011 responses. If no_multiline_responses is TRUE (it can be set from an ACL), we
3012 output nothing for non-final calls, and only the first line for anything else.
3013
3014 Arguments:
3015 code SMTP code, may involve extended status codes
3016 codelen length of smtp code; if > 4 there's an ESC
3017 final FALSE if the last line isn't the final line
3018 msg message text, possibly containing newlines
3019
3020 Returns: nothing
3021 */
3022
3023 void
3024 smtp_respond(uschar* code, int codelen, BOOL final, uschar *msg)
3025 {
3026 int esclen = 0;
3027 uschar *esc = US"";
3028
3029 if (!final && no_multiline_responses) return;
3030
3031 if (codelen > 4)
3032 {
3033 esc = code + 4;
3034 esclen = codelen - 4;
3035 }
3036
3037 /* If this is the first output for a (non-batch) RCPT command, see if all RCPTs
3038 have had the same. Note: this code is also present in smtp_printf(). It would
3039 be tidier to have it only in one place, but when it was added, it was easier to
3040 do it that way, so as not to have to mess with the code for the RCPT command,
3041 which sometimes uses smtp_printf() and sometimes smtp_respond(). */
3042
3043 if (rcpt_in_progress)
3044 {
3045 if (rcpt_smtp_response == NULL)
3046 rcpt_smtp_response = string_copy(msg);
3047 else if (rcpt_smtp_response_same &&
3048 Ustrcmp(rcpt_smtp_response, msg) != 0)
3049 rcpt_smtp_response_same = FALSE;
3050 rcpt_in_progress = FALSE;
3051 }
3052
3053 /* Now output the message, splitting it up into multiple lines if necessary.
3054 We only handle pipelining these responses as far as nonfinal/final groups,
3055 not the whole MAIL/RCPT/DATA response set. */
3056
3057 for (;;)
3058 {
3059 uschar *nl = Ustrchr(msg, '\n');
3060 if (nl == NULL)
3061 {
3062 smtp_printf("%.3s%c%.*s%s\r\n", !final, code, final ? ' ':'-', esclen, esc, msg);
3063 return;
3064 }
3065 else if (nl[1] == 0 || no_multiline_responses)
3066 {
3067 smtp_printf("%.3s%c%.*s%.*s\r\n", !final, code, final ? ' ':'-', esclen, esc,
3068 (int)(nl - msg), msg);
3069 return;
3070 }
3071 else
3072 {
3073 smtp_printf("%.3s-%.*s%.*s\r\n", TRUE, code, esclen, esc, (int)(nl - msg), msg);
3074 msg = nl + 1;
3075 while (isspace(*msg)) msg++;
3076 }
3077 }
3078 }
3079
3080
3081
3082
3083 /*************************************************
3084 * Parse user SMTP message *
3085 *************************************************/
3086
3087 /* This function allows for user messages overriding the response code details
3088 by providing a suitable response code string at the start of the message
3089 user_msg. Check the message for starting with a response code and optionally an
3090 extended status code. If found, check that the first digit is valid, and if so,
3091 change the code pointer and length to use the replacement. An invalid code
3092 causes a panic log; in this case, if the log messages is the same as the user
3093 message, we must also adjust the value of the log message to show the code that
3094 is actually going to be used (the original one).
3095
3096 This function is global because it is called from receive.c as well as within
3097 this module.
3098
3099 Note that the code length returned includes the terminating whitespace
3100 character, which is always included in the regex match.
3101
3102 Arguments:
3103 code SMTP code, may involve extended status codes
3104 codelen length of smtp code; if > 4 there's an ESC
3105 msg message text
3106 log_msg optional log message, to be adjusted with the new SMTP code
3107 check_valid if true, verify the response code
3108
3109 Returns: nothing
3110 */
3111
3112 void
3113 smtp_message_code(uschar **code, int *codelen, uschar **msg, uschar **log_msg,
3114 BOOL check_valid)
3115 {
3116 int n;
3117 int ovector[3];
3118
3119 if (!msg || !*msg) return;
3120
3121 if ((n = pcre_exec(regex_smtp_code, NULL, CS *msg, Ustrlen(*msg), 0,
3122 PCRE_EOPT, ovector, sizeof(ovector)/sizeof(int))) < 0) return;
3123
3124 if (check_valid && (*msg)[0] != (*code)[0])
3125 {
3126 log_write(0, LOG_MAIN|LOG_PANIC, "configured error code starts with "
3127 "incorrect digit (expected %c) in \"%s\"", (*code)[0], *msg);
3128 if (log_msg != NULL && *log_msg == *msg)
3129 *log_msg = string_sprintf("%s %s", *code, *log_msg + ovector[1]);
3130 }
3131 else
3132 {
3133 *code = *msg;
3134 *codelen = ovector[1]; /* Includes final space */
3135 }
3136 *msg += ovector[1]; /* Chop the code off the message */
3137 return;
3138 }
3139
3140
3141
3142
3143 /*************************************************
3144 * Handle an ACL failure *
3145 *************************************************/
3146
3147 /* This function is called when acl_check() fails. As well as calls from within
3148 this module, it is called from receive.c for an ACL after DATA. It sorts out
3149 logging the incident, and sends the error response. A message containing
3150 newlines is turned into a multiline SMTP response, but for logging, only the
3151 first line is used.
3152
3153 There's a table of default permanent failure response codes to use in
3154 globals.c, along with the table of names. VFRY is special. Despite RFC1123 it
3155 defaults disabled in Exim. However, discussion in connection with RFC 821bis
3156 (aka RFC 2821) has concluded that the response should be 252 in the disabled
3157 state, because there are broken clients that try VRFY before RCPT. A 5xx
3158 response should be given only when the address is positively known to be
3159 undeliverable. Sigh. We return 252 if there is no VRFY ACL or it provides
3160 no explicit code, but if there is one we let it know best.
3161 Also, for ETRN, 458 is given on refusal, and for AUTH, 503.
3162
3163 From Exim 4.63, it is possible to override the response code details by
3164 providing a suitable response code string at the start of the message provided
3165 in user_msg. The code's first digit is checked for validity.
3166
3167 Arguments:
3168 where where the ACL was called from
3169 rc the failure code
3170 user_msg a message that can be included in an SMTP response
3171 log_msg a message for logging
3172
3173 Returns: 0 in most cases
3174 2 if the failure code was FAIL_DROP, in which case the
3175 SMTP connection should be dropped (this value fits with the
3176 "done" variable in smtp_setup_msg() below)
3177 */
3178
3179 int
3180 smtp_handle_acl_fail(int where, int rc, uschar *user_msg, uschar *log_msg)
3181 {
3182 BOOL drop = rc == FAIL_DROP;
3183 int codelen = 3;
3184 uschar *smtp_code;
3185 uschar *lognl;
3186 uschar *sender_info = US"";
3187 uschar *what =
3188 #ifdef WITH_CONTENT_SCAN
3189 where == ACL_WHERE_MIME ? US"during MIME ACL checks" :
3190 #endif
3191 where == ACL_WHERE_PREDATA ? US"DATA" :
3192 where == ACL_WHERE_DATA ? US"after DATA" :
3193 #ifndef DISABLE_PRDR
3194 where == ACL_WHERE_PRDR ? US"after DATA PRDR" :
3195 #endif
3196 smtp_cmd_data ?
3197 string_sprintf("%s %s", acl_wherenames[where], smtp_cmd_data) :
3198 string_sprintf("%s in \"connect\" ACL", acl_wherenames[where]);
3199
3200 if (drop) rc = FAIL;
3201
3202 /* Set the default SMTP code, and allow a user message to change it. */
3203
3204 smtp_code = rc == FAIL ? acl_wherecodes[where] : US"451";
3205 smtp_message_code(&smtp_code, &codelen, &user_msg, &log_msg,
3206 where != ACL_WHERE_VRFY);
3207
3208 /* We used to have sender_address here; however, there was a bug that was not
3209 updating sender_address after a rewrite during a verify. When this bug was
3210 fixed, sender_address at this point became the rewritten address. I'm not sure
3211 this is what should be logged, so I've changed to logging the unrewritten
3212 address to retain backward compatibility. */
3213
3214 #ifndef WITH_CONTENT_SCAN
3215 if (where == ACL_WHERE_RCPT || where == ACL_WHERE_DATA)
3216 #else
3217 if (where == ACL_WHERE_RCPT || where == ACL_WHERE_DATA || where == ACL_WHERE_MIME)
3218 #endif
3219 {
3220 sender_info = string_sprintf("F=<%s>%s%s%s%s ",
3221 sender_address_unrewritten ? sender_address_unrewritten : sender_address,
3222 sender_host_authenticated ? US" A=" : US"",
3223 sender_host_authenticated ? sender_host_authenticated : US"",
3224 sender_host_authenticated && authenticated_id ? US":" : US"",
3225 sender_host_authenticated && authenticated_id ? authenticated_id : US""
3226 );
3227 }
3228
3229 /* If there's been a sender verification failure with a specific message, and
3230 we have not sent a response about it yet, do so now, as a preliminary line for
3231 failures, but not defers. However, always log it for defer, and log it for fail
3232 unless the sender_verify_fail log selector has been turned off. */
3233
3234 if (sender_verified_failed &&
3235 !testflag(sender_verified_failed, af_sverify_told))
3236 {
3237 BOOL save_rcpt_in_progress = rcpt_in_progress;
3238 rcpt_in_progress = FALSE; /* So as not to treat these as the error */
3239
3240 setflag(sender_verified_failed, af_sverify_told);
3241
3242 if (rc != FAIL || LOGGING(sender_verify_fail))
3243 log_write(0, LOG_MAIN|LOG_REJECT, "%s sender verify %s for <%s>%s",
3244 host_and_ident(TRUE),
3245 ((sender_verified_failed->special_action & 255) == DEFER)? "defer":"fail",
3246 sender_verified_failed->address,
3247 (sender_verified_failed->message == NULL)? US"" :
3248 string_sprintf(": %s", sender_verified_failed->message));
3249
3250 if (rc == FAIL && sender_verified_failed->user_message)
3251 smtp_respond(smtp_code, codelen, FALSE, string_sprintf(
3252 testflag(sender_verified_failed, af_verify_pmfail)?
3253 "Postmaster verification failed while checking <%s>\n%s\n"
3254 "Several RFCs state that you are required to have a postmaster\n"
3255 "mailbox for each mail domain. This host does not accept mail\n"
3256 "from domains whose servers reject the postmaster address."
3257 :
3258 testflag(sender_verified_failed, af_verify_nsfail)?
3259 "Callback setup failed while verifying <%s>\n%s\n"
3260 "The initial connection, or a HELO or MAIL FROM:<> command was\n"
3261 "rejected. Refusing MAIL FROM:<> does not help fight spam, disregards\n"
3262 "RFC requirements, and stops you from receiving standard bounce\n"
3263 "messages. This host does not accept mail from domains whose servers\n"
3264 "refuse bounces."
3265 :
3266 "Verification failed for <%s>\n%s",
3267 sender_verified_failed->address,
3268 sender_verified_failed->user_message));
3269
3270 rcpt_in_progress = save_rcpt_in_progress;
3271 }
3272
3273 /* Sort out text for logging */
3274
3275 log_msg = log_msg ? string_sprintf(": %s", log_msg) : US"";
3276 if ((lognl = Ustrchr(log_msg, '\n'))) *lognl = 0;
3277
3278 /* Send permanent failure response to the command, but the code used isn't
3279 always a 5xx one - see comments at the start of this function. If the original
3280 rc was FAIL_DROP we drop the connection and yield 2. */
3281
3282 if (rc == FAIL)
3283 smtp_respond(smtp_code, codelen, TRUE,
3284 user_msg ? user_msg : US"Administrative prohibition");
3285
3286 /* Send temporary failure response to the command. Don't give any details,
3287 unless acl_temp_details is set. This is TRUE for a callout defer, a "defer"
3288 verb, and for a header verify when smtp_return_error_details is set.
3289
3290 This conditional logic is all somewhat of a mess because of the odd
3291 interactions between temp_details and return_error_details. One day it should
3292 be re-implemented in a tidier fashion. */
3293
3294 else
3295 if (acl_temp_details && user_msg)
3296 {
3297 if ( smtp_return_error_details
3298 && sender_verified_failed
3299 && sender_verified_failed->message
3300 )
3301 smtp_respond(smtp_code, codelen, FALSE, sender_verified_failed->message);
3302
3303 smtp_respond(smtp_code, codelen, TRUE, user_msg);
3304 }
3305 else
3306 smtp_respond(smtp_code, codelen, TRUE,
3307 US"Temporary local problem - please try later");
3308
3309 /* Log the incident to the logs that are specified by log_reject_target
3310 (default main, reject). This can be empty to suppress logging of rejections. If
3311 the connection is not forcibly to be dropped, return 0. Otherwise, log why it
3312 is closing if required and return 2. */
3313
3314 if (log_reject_target != 0)
3315 {
3316 #ifdef SUPPORT_TLS
3317 gstring * g = s_tlslog(NULL);
3318 uschar * tls = string_from_gstring(g);
3319 if (!tls) tls = US"";
3320 #else
3321 uschar * tls = US"";
3322 #endif
3323 log_write(where == ACL_WHERE_CONNECT ? L_connection_reject : 0,
3324 log_reject_target, "%s%s%s %s%srejected %s%s",
3325 LOGGING(dnssec) && sender_host_dnssec ? US" DS" : US"",
3326 host_and_ident(TRUE),
3327 tls,
3328 sender_info,
3329 rc == FAIL ? US"" : US"temporarily ",
3330 what, log_msg);
3331 }
3332
3333 if (!drop) return 0;
3334
3335 log_write(L_smtp_connection, LOG_MAIN, "%s closed by DROP in ACL",
3336 smtp_get_connection_info());
3337
3338 /* Run the not-quit ACL, but without any custom messages. This should not be a
3339 problem, because we get here only if some other ACL has issued "drop", and
3340 in that case, *its* custom messages will have been used above. */
3341
3342 smtp_notquit_exit(US"acl-drop", NULL, NULL);
3343 return 2;
3344 }
3345
3346
3347
3348
3349 /*************************************************
3350 * Handle SMTP exit when QUIT is not given *
3351 *************************************************/
3352
3353 /* This function provides a logging/statistics hook for when an SMTP connection
3354 is dropped on the floor or the other end goes away. It's a global function
3355 because it's called from receive.c as well as this module. As well as running
3356 the NOTQUIT ACL, if there is one, this function also outputs a final SMTP
3357 response, either with a custom message from the ACL, or using a default. There
3358 is one case, however, when no message is output - after "drop". In that case,
3359 the ACL that obeyed "drop" has already supplied the custom message, and NULL is
3360 passed to this function.
3361
3362 In case things go wrong while processing this function, causing an error that
3363 may re-enter this function, there is a recursion check.
3364
3365 Arguments:
3366 reason What $smtp_notquit_reason will be set to in the ACL;
3367 if NULL, the ACL is not run
3368 code The error code to return as part of the response
3369 defaultrespond The default message if there's no user_msg
3370
3371 Returns: Nothing
3372 */
3373
3374 void
3375 smtp_notquit_exit(uschar *reason, uschar *code, uschar *defaultrespond, ...)
3376 {
3377 int rc;
3378 uschar *user_msg = NULL;
3379 uschar *log_msg = NULL;
3380
3381 /* Check for recursive acll */
3382
3383 if (smtp_exit_function_called)
3384 {
3385 log_write(0, LOG_PANIC, "smtp_notquit_exit() called more than once (%s)",
3386 reason);
3387 return;
3388 }
3389 smtp_exit_function_called = TRUE;
3390
3391 /* Call the not-QUIT ACL, if there is one, unless no reason is given. */
3392
3393 if (acl_smtp_notquit && reason)
3394 {
3395 smtp_notquit_reason = reason;
3396 if ((rc = acl_check(ACL_WHERE_NOTQUIT, NULL, acl_smtp_notquit, &user_msg,
3397 &log_msg)) == ERROR)
3398 log_write(0, LOG_MAIN|LOG_PANIC, "ACL for not-QUIT returned ERROR: %s",
3399 log_msg);
3400 }
3401
3402 /* Write an SMTP response if we are expected to give one. As the default
3403 responses are all internal, they should always fit in the buffer, but code a
3404 warning, just in case. Note that string_vformat() still leaves a complete
3405 string, even if it is incomplete. */
3406
3407 if (code && defaultrespond)
3408 {
3409 if (user_msg)
3410 smtp_respond(code, 3, TRUE, user_msg);
3411 else
3412 {
3413 uschar buffer[128];
3414 va_list ap;
3415 va_start(ap, defaultrespond);
3416 if (!string_vformat(buffer, sizeof(buffer), CS defaultrespond, ap))
3417 log_write(0, LOG_MAIN|LOG_PANIC, "string too large in smtp_notquit_exit()");
3418 smtp_printf("%s %s\r\n", FALSE, code, buffer);
3419 va_end(ap);
3420 }
3421 mac_smtp_fflush();
3422 }
3423 }
3424
3425
3426
3427
3428 /*************************************************
3429 * Verify HELO argument *
3430 *************************************************/
3431
3432 /* This function is called if helo_verify_hosts or helo_try_verify_hosts is
3433 matched. It is also called from ACL processing if verify = helo is used and
3434 verification was not previously tried (i.e. helo_try_verify_hosts was not
3435 matched). The result of its processing is to set helo_verified and
3436 helo_verify_failed. These variables should both be FALSE for this function to
3437 be called.
3438
3439 Note that EHLO/HELO is legitimately allowed to quote an address literal. Allow
3440 for IPv6 ::ffff: literals.
3441
3442 Argument: none
3443 Returns: TRUE if testing was completed;
3444 FALSE on a temporary failure
3445 */
3446
3447 BOOL
3448 smtp_verify_helo(void)
3449 {
3450 BOOL yield = TRUE;
3451
3452 HDEBUG(D_receive) debug_printf("verifying EHLO/HELO argument \"%s\"\n",
3453 sender_helo_name);
3454
3455 if (sender_helo_name == NULL)
3456 {
3457 HDEBUG(D_receive) debug_printf("no EHLO/HELO command was issued\n");
3458 }
3459
3460 /* Deal with the case of -bs without an IP address */
3461
3462 else if (sender_host_address == NULL)
3463 {
3464 HDEBUG(D_receive) debug_printf("no client IP address: assume success\n");
3465 helo_verified = TRUE;
3466 }
3467
3468 /* Deal with the more common case when there is a sending IP address */
3469
3470 else if (sender_helo_name[0] == '[')
3471 {
3472 helo_verified = Ustrncmp(sender_helo_name+1, sender_host_address,
3473 Ustrlen(sender_host_address)) == 0;
3474
3475 #if HAVE_IPV6
3476 if (!helo_verified)
3477 {
3478 if (strncmpic(sender_host_address, US"::ffff:", 7) == 0)
3479 helo_verified = Ustrncmp(sender_helo_name + 1,
3480 sender_host_address + 7, Ustrlen(sender_host_address) - 7) == 0;
3481 }
3482 #endif
3483
3484 HDEBUG(D_receive)
3485 { if (helo_verified) debug_printf("matched host address\n"); }
3486 }
3487
3488 /* Do a reverse lookup if one hasn't already given a positive or negative
3489 response. If that fails, or the name doesn't match, try checking with a forward
3490 lookup. */
3491
3492 else
3493 {
3494 if (sender_host_name == NULL && !host_lookup_failed)
3495 yield = host_name_lookup() != DEFER;
3496
3497 /* If a host name is known, check it and all its aliases. */
3498
3499 if (sender_host_name)
3500 if ((helo_verified = strcmpic(sender_host_name, sender_helo_name) == 0))
3501 {
3502 sender_helo_dnssec = sender_host_dnssec;
3503 HDEBUG(D_receive) debug_printf("matched host name\n");
3504 }
3505 else
3506 {
3507 uschar **aliases = sender_host_aliases;
3508 while (*aliases)
3509 if ((helo_verified = strcmpic(*aliases++, sender_helo_name) == 0))
3510 {
3511 sender_helo_dnssec = sender_host_dnssec;
3512 break;
3513 }
3514
3515 HDEBUG(D_receive) if (helo_verified)