Copyright updates:
[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 /* Copyright (c) The Exim Maintainers 2020 */
7 /* See the file NOTICE for conditions of use and distribution. */
8
9 /* Functions for handling an incoming SMTP call. */
10
11
12 #include "exim.h"
13 #include <assert.h>
14
15
16 /* Initialize for TCP wrappers if so configured. It appears that the macro
17 HAVE_IPV6 is used in some versions of the tcpd.h header, so we unset it before
18 including that header, and restore its value afterwards. */
19
20 #ifdef USE_TCP_WRAPPERS
21
22 #if HAVE_IPV6
23 #define EXIM_HAVE_IPV6
24 #endif
25 #undef HAVE_IPV6
26 #include <tcpd.h>
27 #undef HAVE_IPV6
28 #ifdef EXIM_HAVE_IPV6
29 #define HAVE_IPV6 TRUE
30 #endif
31
32 int allow_severity = LOG_INFO;
33 int deny_severity = LOG_NOTICE;
34 uschar *tcp_wrappers_name;
35 #endif
36
37
38 /* Size of buffer for reading SMTP commands. We used to use 512, as defined
39 by RFC 821. However, RFC 1869 specifies that this must be increased for SMTP
40 commands that accept arguments, and this in particular applies to AUTH, where
41 the data can be quite long. More recently this value was 2048 in Exim;
42 however, RFC 4954 (circa 2007) recommends 12288 bytes to handle AUTH. Clients
43 such as Thunderbird will send an AUTH with an initial-response for GSSAPI.
44 The maximum size of a Kerberos ticket under Windows 2003 is 12000 bytes, and
45 we need room to handle large base64-encoded AUTHs for GSSAPI.
46 */
47
48 #define SMTP_CMD_BUFFER_SIZE 16384
49
50 /* Size of buffer for reading SMTP incoming packets */
51
52 #define IN_BUFFER_SIZE 8192
53
54 /* Structure for SMTP command list */
55
56 typedef struct {
57 const char *name;
58 int len;
59 short int cmd;
60 short int has_arg;
61 short int is_mail_cmd;
62 } smtp_cmd_list;
63
64 /* Codes for identifying commands. We order them so that those that come first
65 are those for which synchronization is always required. Checking this can help
66 block some spam. */
67
68 enum {
69 /* These commands are required to be synchronized, i.e. to be the last in a
70 block of commands when pipelining. */
71
72 HELO_CMD, EHLO_CMD, DATA_CMD, /* These are listed in the pipelining */
73 VRFY_CMD, EXPN_CMD, NOOP_CMD, /* RFC as requiring synchronization */
74 ETRN_CMD, /* This by analogy with TURN from the RFC */
75 STARTTLS_CMD, /* Required by the STARTTLS RFC */
76 TLS_AUTH_CMD, /* auto-command at start of SSL */
77
78 /* This is a dummy to identify the non-sync commands when pipelining */
79
80 NON_SYNC_CMD_PIPELINING,
81
82 /* These commands need not be synchronized when pipelining */
83
84 MAIL_CMD, RCPT_CMD, RSET_CMD,
85
86 /* This is a dummy to identify the non-sync commands when not pipelining */
87
88 NON_SYNC_CMD_NON_PIPELINING,
89
90 /* RFC3030 section 2: "After all MAIL and RCPT responses are collected and
91 processed the message is sent using a series of BDAT commands"
92 implies that BDAT should be synchronized. However, we see Google, at least,
93 sending MAIL,RCPT,BDAT-LAST in a single packet, clearly not waiting for
94 processing of the RCPT response(s). We shall do the same, and not require
95 synch for BDAT. Worse, as the chunk may (very likely will) follow the
96 command-header in the same packet we cannot do the usual "is there any
97 follow-on data after the command line" even for non-pipeline mode.
98 So we'll need an explicit check after reading the expected chunk amount
99 when non-pipe, before sending the ACK. */
100
101 BDAT_CMD,
102
103 /* I have been unable to find a statement about the use of pipelining
104 with AUTH, so to be on the safe side it is here, though I kind of feel
105 it should be up there with the synchronized commands. */
106
107 AUTH_CMD,
108
109 /* I'm not sure about these, but I don't think they matter. */
110
111 QUIT_CMD, HELP_CMD,
112
113 #ifdef SUPPORT_PROXY
114 PROXY_FAIL_IGNORE_CMD,
115 #endif
116
117 /* These are specials that don't correspond to actual commands */
118
119 EOF_CMD, OTHER_CMD, BADARG_CMD, BADCHAR_CMD, BADSYN_CMD,
120 TOO_MANY_NONMAIL_CMD };
121
122
123 /* This is a convenience macro for adding the identity of an SMTP command
124 to the circular buffer that holds a list of the last n received. */
125
126 #define HAD(n) \
127 smtp_connection_had[smtp_ch_index++] = n; \
128 if (smtp_ch_index >= SMTP_HBUFF_SIZE) smtp_ch_index = 0
129
130
131 /*************************************************
132 * Local static variables *
133 *************************************************/
134
135 static struct {
136 BOOL auth_advertised :1;
137 #ifndef DISABLE_TLS
138 BOOL tls_advertised :1;
139 #endif
140 BOOL dsn_advertised :1;
141 BOOL esmtp :1;
142 BOOL helo_required :1;
143 BOOL helo_verify :1;
144 BOOL helo_seen :1;
145 BOOL helo_accept_junk :1;
146 #ifndef DISABLE_PIPE_CONNECT
147 BOOL pipe_connect_acceptable :1;
148 #endif
149 BOOL rcpt_smtp_response_same :1;
150 BOOL rcpt_in_progress :1;
151 BOOL smtp_exit_function_called :1;
152 #ifdef SUPPORT_I18N
153 BOOL smtputf8_advertised :1;
154 #endif
155 } fl = {
156 .helo_required = FALSE,
157 .helo_verify = FALSE,
158 .smtp_exit_function_called = FALSE,
159 };
160
161 static auth_instance *authenticated_by;
162 static int count_nonmail;
163 static int nonmail_command_count;
164 static int synprot_error_count;
165 static int unknown_command_count;
166 static int sync_cmd_limit;
167 static int smtp_write_error = 0;
168
169 static uschar *rcpt_smtp_response;
170 static uschar *smtp_data_buffer;
171 static uschar *smtp_cmd_data;
172
173 /* We need to know the position of RSET, HELO, EHLO, AUTH, and STARTTLS. Their
174 final fields of all except AUTH are forced TRUE at the start of a new message
175 setup, to allow one of each between messages that is not counted as a nonmail
176 command. (In fact, only one of HELO/EHLO is not counted.) Also, we have to
177 allow a new EHLO after starting up TLS.
178
179 AUTH is "falsely" labelled as a mail command initially, so that it doesn't get
180 counted. However, the flag is changed when AUTH is received, so that multiple
181 failing AUTHs will eventually hit the limit. After a successful AUTH, another
182 AUTH is already forbidden. After a TLS session is started, AUTH's flag is again
183 forced TRUE, to allow for the re-authentication that can happen at that point.
184
185 QUIT is also "falsely" labelled as a mail command so that it doesn't up the
186 count of non-mail commands and possibly provoke an error.
187
188 tls_auth is a pseudo-command, never expected in input. It is activated
189 on TLS startup and looks for a tls authenticator. */
190
191 static smtp_cmd_list cmd_list[] = {
192 /* name len cmd has_arg is_mail_cmd */
193
194 { "rset", sizeof("rset")-1, RSET_CMD, FALSE, FALSE }, /* First */
195 { "helo", sizeof("helo")-1, HELO_CMD, TRUE, FALSE },
196 { "ehlo", sizeof("ehlo")-1, EHLO_CMD, TRUE, FALSE },
197 { "auth", sizeof("auth")-1, AUTH_CMD, TRUE, TRUE },
198 #ifndef DISABLE_TLS
199 { "starttls", sizeof("starttls")-1, STARTTLS_CMD, FALSE, FALSE },
200 { "tls_auth", 0, TLS_AUTH_CMD, FALSE, FALSE },
201 #endif
202
203 /* If you change anything above here, also fix the definitions below. */
204
205 { "mail from:", sizeof("mail from:")-1, MAIL_CMD, TRUE, TRUE },
206 { "rcpt to:", sizeof("rcpt to:")-1, RCPT_CMD, TRUE, TRUE },
207 { "data", sizeof("data")-1, DATA_CMD, FALSE, TRUE },
208 { "bdat", sizeof("bdat")-1, BDAT_CMD, TRUE, TRUE },
209 { "quit", sizeof("quit")-1, QUIT_CMD, FALSE, TRUE },
210 { "noop", sizeof("noop")-1, NOOP_CMD, TRUE, FALSE },
211 { "etrn", sizeof("etrn")-1, ETRN_CMD, TRUE, FALSE },
212 { "vrfy", sizeof("vrfy")-1, VRFY_CMD, TRUE, FALSE },
213 { "expn", sizeof("expn")-1, EXPN_CMD, TRUE, FALSE },
214 { "help", sizeof("help")-1, HELP_CMD, TRUE, FALSE }
215 };
216
217 static smtp_cmd_list *cmd_list_end =
218 cmd_list + sizeof(cmd_list)/sizeof(smtp_cmd_list);
219
220 #define CMD_LIST_RSET 0
221 #define CMD_LIST_HELO 1
222 #define CMD_LIST_EHLO 2
223 #define CMD_LIST_AUTH 3
224 #define CMD_LIST_STARTTLS 4
225 #define CMD_LIST_TLS_AUTH 5
226
227 /* This list of names is used for performing the smtp_no_mail logging action.
228 It must be kept in step with the SCH_xxx enumerations. */
229
230 static uschar *smtp_names[] =
231 {
232 US"NONE", US"AUTH", US"DATA", US"BDAT", US"EHLO", US"ETRN", US"EXPN",
233 US"HELO", US"HELP", US"MAIL", US"NOOP", US"QUIT", US"RCPT", US"RSET",
234 US"STARTTLS", US"VRFY" };
235
236 static uschar *protocols_local[] = {
237 US"local-smtp", /* HELO */
238 US"local-smtps", /* The rare case EHLO->STARTTLS->HELO */
239 US"local-esmtp", /* EHLO */
240 US"local-esmtps", /* EHLO->STARTTLS->EHLO */
241 US"local-esmtpa", /* EHLO->AUTH */
242 US"local-esmtpsa" /* EHLO->STARTTLS->EHLO->AUTH */
243 };
244 static uschar *protocols[] = {
245 US"smtp", /* HELO */
246 US"smtps", /* The rare case EHLO->STARTTLS->HELO */
247 US"esmtp", /* EHLO */
248 US"esmtps", /* EHLO->STARTTLS->EHLO */
249 US"esmtpa", /* EHLO->AUTH */
250 US"esmtpsa" /* EHLO->STARTTLS->EHLO->AUTH */
251 };
252
253 #define pnormal 0
254 #define pextend 2
255 #define pcrpted 1 /* added to pextend or pnormal */
256 #define pauthed 2 /* added to pextend */
257
258 /* Sanity check and validate optional args to MAIL FROM: envelope */
259 enum {
260 ENV_MAIL_OPT_NULL,
261 ENV_MAIL_OPT_SIZE, ENV_MAIL_OPT_BODY, ENV_MAIL_OPT_AUTH,
262 #ifndef DISABLE_PRDR
263 ENV_MAIL_OPT_PRDR,
264 #endif
265 ENV_MAIL_OPT_RET, ENV_MAIL_OPT_ENVID,
266 #ifdef SUPPORT_I18N
267 ENV_MAIL_OPT_UTF8,
268 #endif
269 };
270 typedef struct {
271 uschar * name; /* option requested during MAIL cmd */
272 int value; /* enum type */
273 BOOL need_value; /* TRUE requires value (name=value pair format)
274 FALSE is a singleton */
275 } env_mail_type_t;
276 static env_mail_type_t env_mail_type_list[] = {
277 { US"SIZE", ENV_MAIL_OPT_SIZE, TRUE },
278 { US"BODY", ENV_MAIL_OPT_BODY, TRUE },
279 { US"AUTH", ENV_MAIL_OPT_AUTH, TRUE },
280 #ifndef DISABLE_PRDR
281 { US"PRDR", ENV_MAIL_OPT_PRDR, FALSE },
282 #endif
283 { US"RET", ENV_MAIL_OPT_RET, TRUE },
284 { US"ENVID", ENV_MAIL_OPT_ENVID, TRUE },
285 #ifdef SUPPORT_I18N
286 { US"SMTPUTF8",ENV_MAIL_OPT_UTF8, FALSE }, /* rfc6531 */
287 #endif
288 /* keep this the last entry */
289 { US"NULL", ENV_MAIL_OPT_NULL, FALSE },
290 };
291
292 /* When reading SMTP from a remote host, we have to use our own versions of the
293 C input-reading functions, in order to be able to flush the SMTP output only
294 when about to read more data from the socket. This is the only way to get
295 optimal performance when the client is using pipelining. Flushing for every
296 command causes a separate packet and reply packet each time; saving all the
297 responses up (when pipelining) combines them into one packet and one response.
298
299 For simplicity, these functions are used for *all* SMTP input, not only when
300 receiving over a socket. However, after setting up a secure socket (SSL), input
301 is read via the OpenSSL library, and another set of functions is used instead
302 (see tls.c).
303
304 These functions are set in the receive_getc etc. variables and called with the
305 same interface as the C functions. However, since there can only ever be
306 one incoming SMTP call, we just use a single buffer and flags. There is no need
307 to implement a complicated private FILE-like structure.*/
308
309 static uschar *smtp_inbuffer;
310 static uschar *smtp_inptr;
311 static uschar *smtp_inend;
312 static int smtp_had_eof;
313 static int smtp_had_error;
314
315
316 /* forward declarations */
317 static int smtp_read_command(BOOL check_sync, unsigned buffer_lim);
318 static int synprot_error(int type, int code, uschar *data, uschar *errmess);
319 static void smtp_quit_handler(uschar **, uschar **);
320 static void smtp_rset_handler(void);
321
322 /*************************************************
323 * Recheck synchronization *
324 *************************************************/
325
326 /* Synchronization checks can never be perfect because a packet may be on its
327 way but not arrived when the check is done. Normally, the checks happen when
328 commands are read: Exim ensures that there is no more input in the input buffer.
329 In normal cases, the response to the command will be fast, and there is no
330 further check.
331
332 However, for some commands an ACL is run, and that can include delays. In those
333 cases, it is useful to do another check on the input just before sending the
334 response. This also applies at the start of a connection. This function does
335 that check by means of the select() function, as long as the facility is not
336 disabled or inappropriate. A failure of select() is ignored.
337
338 When there is unwanted input, we read it so that it appears in the log of the
339 error.
340
341 Arguments: none
342 Returns: TRUE if all is well; FALSE if there is input pending
343 */
344
345 static BOOL
346 wouldblock_reading(void)
347 {
348 int fd, rc;
349 fd_set fds;
350 struct timeval tzero;
351
352 #ifndef DISABLE_TLS
353 if (tls_in.active.sock >= 0)
354 return !tls_could_read();
355 #endif
356
357 if (smtp_inptr < smtp_inend)
358 return FALSE;
359
360 fd = fileno(smtp_in);
361 FD_ZERO(&fds);
362 FD_SET(fd, &fds);
363 tzero.tv_sec = 0;
364 tzero.tv_usec = 0;
365 rc = select(fd + 1, (SELECT_ARG2_TYPE *)&fds, NULL, NULL, &tzero);
366
367 if (rc <= 0) return TRUE; /* Not ready to read */
368 rc = smtp_getc(GETC_BUFFER_UNLIMITED);
369 if (rc < 0) return TRUE; /* End of file or error */
370
371 smtp_ungetc(rc);
372 return FALSE;
373 }
374
375 static BOOL
376 check_sync(void)
377 {
378 if (!smtp_enforce_sync || !sender_host_address || f.sender_host_notsocket)
379 return TRUE;
380
381 return wouldblock_reading();
382 }
383
384
385 /* If there's input waiting (and we're doing pipelineing) then we can pipeline
386 a reponse with the one following. */
387
388 static BOOL
389 pipeline_response(void)
390 {
391 if ( !smtp_enforce_sync || !sender_host_address
392 || f.sender_host_notsocket || !f.smtp_in_pipelining_advertised)
393 return FALSE;
394
395 if (wouldblock_reading()) return FALSE;
396 f.smtp_in_pipelining_used = TRUE;
397 return TRUE;
398 }
399
400
401 #ifndef DISABLE_PIPE_CONNECT
402 static BOOL
403 pipeline_connect_sends(void)
404 {
405 if (!sender_host_address || f.sender_host_notsocket || !fl.pipe_connect_acceptable)
406 return FALSE;
407
408 if (wouldblock_reading()) return FALSE;
409 f.smtp_in_early_pipe_used = TRUE;
410 return TRUE;
411 }
412 #endif
413
414 /*************************************************
415 * Log incomplete transactions *
416 *************************************************/
417
418 /* This function is called after a transaction has been aborted by RSET, QUIT,
419 connection drops or other errors. It logs the envelope information received
420 so far in order to preserve address verification attempts.
421
422 Argument: string to indicate what aborted the transaction
423 Returns: nothing
424 */
425
426 static void
427 incomplete_transaction_log(uschar *what)
428 {
429 if (!sender_address /* No transaction in progress */
430 || !LOGGING(smtp_incomplete_transaction))
431 return;
432
433 /* Build list of recipients for logging */
434
435 if (recipients_count > 0)
436 {
437 raw_recipients = store_get(recipients_count * sizeof(uschar *), FALSE);
438 for (int i = 0; i < recipients_count; i++)
439 raw_recipients[i] = recipients_list[i].address;
440 raw_recipients_count = recipients_count;
441 }
442
443 log_write(L_smtp_incomplete_transaction, LOG_MAIN|LOG_SENDER|LOG_RECIPIENTS,
444 "%s incomplete transaction (%s)", host_and_ident(TRUE), what);
445 }
446
447
448
449
450 void
451 smtp_command_timeout_exit(void)
452 {
453 log_write(L_lost_incoming_connection,
454 LOG_MAIN, "SMTP command timeout on%s connection from %s",
455 tls_in.active.sock >= 0 ? " TLS" : "", host_and_ident(FALSE));
456 if (smtp_batched_input)
457 moan_smtp_batch(NULL, "421 SMTP command timeout"); /* Does not return */
458 smtp_notquit_exit(US"command-timeout", US"421",
459 US"%s: SMTP command timeout - closing connection",
460 smtp_active_hostname);
461 exim_exit(EXIT_FAILURE);
462 }
463
464 void
465 smtp_command_sigterm_exit(void)
466 {
467 log_write(0, LOG_MAIN, "%s closed after SIGTERM", smtp_get_connection_info());
468 if (smtp_batched_input)
469 moan_smtp_batch(NULL, "421 SIGTERM received"); /* Does not return */
470 smtp_notquit_exit(US"signal-exit", US"421",
471 US"%s: Service not available - closing connection", smtp_active_hostname);
472 exim_exit(EXIT_FAILURE);
473 }
474
475 void
476 smtp_data_timeout_exit(void)
477 {
478 log_write(L_lost_incoming_connection,
479 LOG_MAIN, "SMTP data timeout (message abandoned) on connection from %s F=<%s>",
480 sender_fullhost ? sender_fullhost : US"local process", sender_address);
481 receive_bomb_out(US"data-timeout", US"SMTP incoming data timeout");
482 /* Does not return */
483 }
484
485 void
486 smtp_data_sigint_exit(void)
487 {
488 log_write(0, LOG_MAIN, "%s closed after %s",
489 smtp_get_connection_info(), had_data_sigint == SIGTERM ? "SIGTERM":"SIGINT");
490 receive_bomb_out(US"signal-exit",
491 US"Service not available - SIGTERM or SIGINT received");
492 /* Does not return */
493 }
494
495
496
497 /* Refill the buffer, and notify DKIM verification code.
498 Return false for error or EOF.
499 */
500
501 static BOOL
502 smtp_refill(unsigned lim)
503 {
504 int rc, save_errno;
505 if (!smtp_out) return FALSE;
506 fflush(smtp_out);
507 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
508
509 /* Limit amount read, so non-message data is not fed to DKIM.
510 Take care to not touch the safety NUL at the end of the buffer. */
511
512 rc = read(fileno(smtp_in), smtp_inbuffer, MIN(IN_BUFFER_SIZE-1, lim));
513 save_errno = errno;
514 if (smtp_receive_timeout > 0) ALARM_CLR(0);
515 if (rc <= 0)
516 {
517 /* Must put the error text in fixed store, because this might be during
518 header reading, where it releases unused store above the header. */
519 if (rc < 0)
520 {
521 if (had_command_timeout) /* set by signal handler */
522 smtp_command_timeout_exit(); /* does not return */
523 if (had_command_sigterm)
524 smtp_command_sigterm_exit();
525 if (had_data_timeout)
526 smtp_data_timeout_exit();
527 if (had_data_sigint)
528 smtp_data_sigint_exit();
529
530 smtp_had_error = save_errno;
531 smtp_read_error = string_copy_perm(
532 string_sprintf(" (error: %s)", strerror(save_errno)), FALSE);
533 }
534 else
535 smtp_had_eof = 1;
536 return FALSE;
537 }
538 #ifndef DISABLE_DKIM
539 dkim_exim_verify_feed(smtp_inbuffer, rc);
540 #endif
541 smtp_inend = smtp_inbuffer + rc;
542 smtp_inptr = smtp_inbuffer;
543 return TRUE;
544 }
545
546 /*************************************************
547 * SMTP version of getc() *
548 *************************************************/
549
550 /* This gets the next byte from the SMTP input buffer. If the buffer is empty,
551 it flushes the output, and refills the buffer, with a timeout. The signal
552 handler is set appropriately by the calling function. This function is not used
553 after a connection has negotiated itself into an TLS/SSL state.
554
555 Arguments: lim Maximum amount to read/buffer
556 Returns: the next character or EOF
557 */
558
559 int
560 smtp_getc(unsigned lim)
561 {
562 if (smtp_inptr >= smtp_inend)
563 if (!smtp_refill(lim))
564 return EOF;
565 return *smtp_inptr++;
566 }
567
568 uschar *
569 smtp_getbuf(unsigned * len)
570 {
571 unsigned size;
572 uschar * buf;
573
574 if (smtp_inptr >= smtp_inend)
575 if (!smtp_refill(*len))
576 { *len = 0; return NULL; }
577
578 if ((size = smtp_inend - smtp_inptr) > *len) size = *len;
579 buf = smtp_inptr;
580 smtp_inptr += size;
581 *len = size;
582 return buf;
583 }
584
585 void
586 smtp_get_cache(void)
587 {
588 #ifndef DISABLE_DKIM
589 int n = smtp_inend - smtp_inptr;
590 if (n > 0)
591 dkim_exim_verify_feed(smtp_inptr, n);
592 #endif
593 }
594
595
596 /* Get a byte from the smtp input, in CHUNKING mode. Handle ack of the
597 previous BDAT chunk and getting new ones when we run out. Uses the
598 underlying smtp_getc or tls_getc both for that and for getting the
599 (buffered) data byte. EOD signals (an expected) no further data.
600 ERR signals a protocol error, and EOF a closed input stream.
601
602 Called from read_bdat_smtp() in receive.c for the message body, but also
603 by the headers read loop in receive_msg(); manipulates chunking_state
604 to handle the BDAT command/response.
605 Placed here due to the correlation with the above smtp_getc(), which it wraps,
606 and also by the need to do smtp command/response handling.
607
608 Arguments: lim (ignored)
609 Returns: the next character or ERR, EOD or EOF
610 */
611
612 int
613 bdat_getc(unsigned lim)
614 {
615 uschar * user_msg = NULL;
616 uschar * log_msg;
617
618 for(;;)
619 {
620 #ifndef DISABLE_DKIM
621 unsigned dkim_save;
622 #endif
623
624 if (chunking_data_left > 0)
625 return lwr_receive_getc(chunking_data_left--);
626
627 receive_getc = lwr_receive_getc;
628 receive_getbuf = lwr_receive_getbuf;
629 receive_ungetc = lwr_receive_ungetc;
630 #ifndef DISABLE_DKIM
631 dkim_save = dkim_collect_input;
632 dkim_collect_input = 0;
633 #endif
634
635 /* Unless PIPELINING was offered, there should be no next command
636 until after we ack that chunk */
637
638 if (!f.smtp_in_pipelining_advertised && !check_sync())
639 {
640 unsigned n = smtp_inend - smtp_inptr;
641 if (n > 32) n = 32;
642
643 incomplete_transaction_log(US"sync failure");
644 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP protocol synchronization error "
645 "(next input sent too soon: pipelining was not advertised): "
646 "rejected \"%s\" %s next input=\"%s\"%s",
647 smtp_cmd_buffer, host_and_ident(TRUE),
648 string_printing(string_copyn(smtp_inptr, n)),
649 smtp_inend - smtp_inptr > n ? "..." : "");
650 (void) synprot_error(L_smtp_protocol_error, 554, NULL,
651 US"SMTP synchronization error");
652 goto repeat_until_rset;
653 }
654
655 /* If not the last, ack the received chunk. The last response is delayed
656 until after the data ACL decides on it */
657
658 if (chunking_state == CHUNKING_LAST)
659 {
660 #ifndef DISABLE_DKIM
661 dkim_exim_verify_feed(NULL, 0); /* notify EOD */
662 #endif
663 return EOD;
664 }
665
666 smtp_printf("250 %u byte chunk received\r\n", FALSE, chunking_datasize);
667 chunking_state = CHUNKING_OFFERED;
668 DEBUG(D_receive) debug_printf("chunking state %d\n", (int)chunking_state);
669
670 /* Expect another BDAT cmd from input. RFC 3030 says nothing about
671 QUIT, RSET or NOOP but handling them seems obvious */
672
673 next_cmd:
674 switch(smtp_read_command(TRUE, 1))
675 {
676 default:
677 (void) synprot_error(L_smtp_protocol_error, 503, NULL,
678 US"only BDAT permissible after non-LAST BDAT");
679
680 repeat_until_rset:
681 switch(smtp_read_command(TRUE, 1))
682 {
683 case QUIT_CMD: smtp_quit_handler(&user_msg, &log_msg); /*FALLTHROUGH */
684 case EOF_CMD: return EOF;
685 case RSET_CMD: smtp_rset_handler(); return ERR;
686 default: if (synprot_error(L_smtp_protocol_error, 503, NULL,
687 US"only RSET accepted now") > 0)
688 return EOF;
689 goto repeat_until_rset;
690 }
691
692 case QUIT_CMD:
693 smtp_quit_handler(&user_msg, &log_msg);
694 /*FALLTHROUGH*/
695 case EOF_CMD:
696 return EOF;
697
698 case RSET_CMD:
699 smtp_rset_handler();
700 return ERR;
701
702 case NOOP_CMD:
703 HAD(SCH_NOOP);
704 smtp_printf("250 OK\r\n", FALSE);
705 goto next_cmd;
706
707 case BDAT_CMD:
708 {
709 int n;
710
711 if (sscanf(CS smtp_cmd_data, "%u %n", &chunking_datasize, &n) < 1)
712 {
713 (void) synprot_error(L_smtp_protocol_error, 501, NULL,
714 US"missing size for BDAT command");
715 return ERR;
716 }
717 chunking_state = strcmpic(smtp_cmd_data+n, US"LAST") == 0
718 ? CHUNKING_LAST : CHUNKING_ACTIVE;
719 chunking_data_left = chunking_datasize;
720 DEBUG(D_receive) debug_printf("chunking state %d, %d bytes\n",
721 (int)chunking_state, chunking_data_left);
722
723 if (chunking_datasize == 0)
724 if (chunking_state == CHUNKING_LAST)
725 return EOD;
726 else
727 {
728 (void) synprot_error(L_smtp_protocol_error, 504, NULL,
729 US"zero size for BDAT command");
730 goto repeat_until_rset;
731 }
732
733 receive_getc = bdat_getc;
734 receive_getbuf = bdat_getbuf; /* r~getbuf is never actually used */
735 receive_ungetc = bdat_ungetc;
736 #ifndef DISABLE_DKIM
737 dkim_collect_input = dkim_save;
738 #endif
739 break; /* to top of main loop */
740 }
741 }
742 }
743 }
744
745 uschar *
746 bdat_getbuf(unsigned * len)
747 {
748 uschar * buf;
749
750 if (chunking_data_left <= 0)
751 { *len = 0; return NULL; }
752
753 if (*len > chunking_data_left) *len = chunking_data_left;
754 buf = lwr_receive_getbuf(len); /* Either smtp_getbuf or tls_getbuf */
755 chunking_data_left -= *len;
756 return buf;
757 }
758
759 void
760 bdat_flush_data(void)
761 {
762 while (chunking_data_left)
763 {
764 unsigned n = chunking_data_left;
765 if (!bdat_getbuf(&n)) break;
766 }
767
768 receive_getc = lwr_receive_getc;
769 receive_getbuf = lwr_receive_getbuf;
770 receive_ungetc = lwr_receive_ungetc;
771
772 if (chunking_state != CHUNKING_LAST)
773 {
774 chunking_state = CHUNKING_OFFERED;
775 DEBUG(D_receive) debug_printf("chunking state %d\n", (int)chunking_state);
776 }
777 }
778
779
780
781
782 /*************************************************
783 * SMTP version of ungetc() *
784 *************************************************/
785
786 /* Puts a character back in the input buffer. Only ever
787 called once.
788
789 Arguments:
790 ch the character
791
792 Returns: the character
793 */
794
795 int
796 smtp_ungetc(int ch)
797 {
798 *--smtp_inptr = ch;
799 return ch;
800 }
801
802
803 int
804 bdat_ungetc(int ch)
805 {
806 chunking_data_left++;
807 return lwr_receive_ungetc(ch);
808 }
809
810
811
812 /*************************************************
813 * SMTP version of feof() *
814 *************************************************/
815
816 /* Tests for a previous EOF
817
818 Arguments: none
819 Returns: non-zero if the eof flag is set
820 */
821
822 int
823 smtp_feof(void)
824 {
825 return smtp_had_eof;
826 }
827
828
829
830
831 /*************************************************
832 * SMTP version of ferror() *
833 *************************************************/
834
835 /* Tests for a previous read error, and returns with errno
836 restored to what it was when the error was detected.
837
838 Arguments: none
839 Returns: non-zero if the error flag is set
840 */
841
842 int
843 smtp_ferror(void)
844 {
845 errno = smtp_had_error;
846 return smtp_had_error;
847 }
848
849
850
851 /*************************************************
852 * Test for characters in the SMTP buffer *
853 *************************************************/
854
855 /* Used at the end of a message
856
857 Arguments: none
858 Returns: TRUE/FALSE
859 */
860
861 BOOL
862 smtp_buffered(void)
863 {
864 return smtp_inptr < smtp_inend;
865 }
866
867
868
869 /*************************************************
870 * Write formatted string to SMTP channel *
871 *************************************************/
872
873 /* This is a separate function so that we don't have to repeat everything for
874 TLS support or debugging. It is global so that the daemon and the
875 authentication functions can use it. It does not return any error indication,
876 because major problems such as dropped connections won't show up till an output
877 flush for non-TLS connections. The smtp_fflush() function is available for
878 checking that: for convenience, TLS output errors are remembered here so that
879 they are also picked up later by smtp_fflush().
880
881 This function is exposed to the local_scan API; do not change the signature.
882
883 Arguments:
884 format format string
885 more further data expected
886 ... optional arguments
887
888 Returns: nothing
889 */
890
891 void
892 smtp_printf(const char *format, BOOL more, ...)
893 {
894 va_list ap;
895
896 va_start(ap, more);
897 smtp_vprintf(format, more, ap);
898 va_end(ap);
899 }
900
901 /* This is split off so that verify.c:respond_printf() can, in effect, call
902 smtp_printf(), bearing in mind that in C a vararg function can't directly
903 call another vararg function, only a function which accepts a va_list.
904
905 This function is exposed to the local_scan API; do not change the signature.
906 */
907 /*XXX consider passing caller-info in, for string_vformat-onward */
908
909 void
910 smtp_vprintf(const char *format, BOOL more, va_list ap)
911 {
912 gstring gs = { .size = big_buffer_size, .ptr = 0, .s = big_buffer };
913 BOOL yield;
914
915 /* Use taint-unchecked routines for writing into big_buffer, trusting
916 that we'll never expand it. */
917
918 yield = !! string_vformat(&gs, SVFMT_TAINT_NOCHK, format, ap);
919 string_from_gstring(&gs);
920
921 DEBUG(D_receive)
922 {
923 uschar *msg_copy, *cr, *end;
924 msg_copy = string_copy(gs.s);
925 end = msg_copy + gs.ptr;
926 while ((cr = Ustrchr(msg_copy, '\r')) != NULL) /* lose CRs */
927 memmove(cr, cr + 1, (end--) - cr);
928 debug_printf("SMTP>> %s", msg_copy);
929 }
930
931 if (!yield)
932 {
933 log_write(0, LOG_MAIN|LOG_PANIC, "string too large in smtp_printf()");
934 smtp_closedown(US"Unexpected error");
935 exim_exit(EXIT_FAILURE);
936 }
937
938 /* If this is the first output for a (non-batch) RCPT command, see if all RCPTs
939 have had the same. Note: this code is also present in smtp_respond(). It would
940 be tidier to have it only in one place, but when it was added, it was easier to
941 do it that way, so as not to have to mess with the code for the RCPT command,
942 which sometimes uses smtp_printf() and sometimes smtp_respond(). */
943
944 if (fl.rcpt_in_progress)
945 {
946 if (rcpt_smtp_response == NULL)
947 rcpt_smtp_response = string_copy(big_buffer);
948 else if (fl.rcpt_smtp_response_same &&
949 Ustrcmp(rcpt_smtp_response, big_buffer) != 0)
950 fl.rcpt_smtp_response_same = FALSE;
951 fl.rcpt_in_progress = FALSE;
952 }
953
954 /* Now write the string */
955
956 if (
957 #ifndef DISABLE_TLS
958 tls_in.active.sock >= 0 ? (tls_write(NULL, gs.s, gs.ptr, more) < 0) :
959 #endif
960 (fwrite(gs.s, gs.ptr, 1, smtp_out) == 0)
961 )
962 smtp_write_error = -1;
963 }
964
965
966
967 /*************************************************
968 * Flush SMTP out and check for error *
969 *************************************************/
970
971 /* This function isn't currently used within Exim (it detects errors when it
972 tries to read the next SMTP input), but is available for use in local_scan().
973 It flushes the output and checks for errors.
974
975 Arguments: none
976 Returns: 0 for no error; -1 after an error
977 */
978
979 int
980 smtp_fflush(void)
981 {
982 if (tls_in.active.sock < 0 && fflush(smtp_out) != 0) smtp_write_error = -1;
983
984 if (
985 #ifndef DISABLE_TLS
986 tls_in.active.sock >= 0 ? (tls_write(NULL, NULL, 0, FALSE) < 0) :
987 #endif
988 (fflush(smtp_out) != 0)
989 )
990 smtp_write_error = -1;
991
992 return smtp_write_error;
993 }
994
995
996
997 /*************************************************
998 * SMTP command read timeout *
999 *************************************************/
1000
1001 /* Signal handler for timing out incoming SMTP commands. This attempts to
1002 finish off tidily.
1003
1004 Argument: signal number (SIGALRM)
1005 Returns: nothing
1006 */
1007
1008 static void
1009 command_timeout_handler(int sig)
1010 {
1011 had_command_timeout = sig;
1012 }
1013
1014
1015
1016 /*************************************************
1017 * SIGTERM received *
1018 *************************************************/
1019
1020 /* Signal handler for handling SIGTERM. Again, try to finish tidily.
1021
1022 Argument: signal number (SIGTERM)
1023 Returns: nothing
1024 */
1025
1026 static void
1027 command_sigterm_handler(int sig)
1028 {
1029 had_command_sigterm = sig;
1030 }
1031
1032
1033
1034
1035 #ifdef SUPPORT_PROXY
1036 /*************************************************
1037 * Restore socket timeout to previous value *
1038 *************************************************/
1039 /* If the previous value was successfully retrieved, restore
1040 it before returning control to the non-proxy routines
1041
1042 Arguments: fd - File descriptor for input
1043 get_ok - Successfully retrieved previous values
1044 tvtmp - Time struct with previous values
1045 vslen - Length of time struct
1046 Returns: none
1047 */
1048 static void
1049 restore_socket_timeout(int fd, int get_ok, struct timeval * tvtmp, socklen_t vslen)
1050 {
1051 if (get_ok == 0)
1052 (void) setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, CS tvtmp, vslen);
1053 }
1054
1055 /*************************************************
1056 * Check if host is required proxy host *
1057 *************************************************/
1058 /* The function determines if inbound host will be a regular smtp host
1059 or if it is configured that it must use Proxy Protocol. A local
1060 connection cannot.
1061
1062 Arguments: none
1063 Returns: bool
1064 */
1065
1066 static BOOL
1067 check_proxy_protocol_host()
1068 {
1069 int rc;
1070
1071 if ( sender_host_address
1072 && (rc = verify_check_this_host(CUSS &hosts_proxy, NULL, NULL,
1073 sender_host_address, NULL)) == OK)
1074 {
1075 DEBUG(D_receive)
1076 debug_printf("Detected proxy protocol configured host\n");
1077 proxy_session = TRUE;
1078 }
1079 return proxy_session;
1080 }
1081
1082
1083 /*************************************************
1084 * Read data until newline or end of buffer *
1085 *************************************************/
1086 /* While SMTP is server-speaks-first, TLS is client-speaks-first, so we can't
1087 read an entire buffer and assume there will be nothing past a proxy protocol
1088 header. Our approach normally is to use stdio, but again that relies upon
1089 "STARTTLS\r\n" and a server response before the client starts TLS handshake, or
1090 reading _nothing_ before client TLS handshake. So we don't want to use the
1091 usual buffering reads which may read enough to block TLS starting.
1092
1093 So unfortunately we're down to "read one byte at a time, with a syscall each,
1094 and expect a little overhead", for all proxy-opened connections which are v1,
1095 just to handle the TLS-on-connect case. Since SSL functions wrap the
1096 underlying fd, we can't assume that we can feed them any already-read content.
1097
1098 We need to know where to read to, the max capacity, and we'll read until we
1099 get a CR and one more character. Let the caller scream if it's CR+!LF.
1100
1101 Return the amount read.
1102 */
1103
1104 static int
1105 swallow_until_crlf(int fd, uschar *base, int already, int capacity)
1106 {
1107 uschar *to = base + already;
1108 uschar *cr;
1109 int have = 0;
1110 int ret;
1111 int last = 0;
1112
1113 /* For "PROXY UNKNOWN\r\n" we, at time of writing, expect to have read
1114 up through the \r; for the _normal_ case, we haven't yet seen the \r. */
1115
1116 cr = memchr(base, '\r', already);
1117 if (cr != NULL)
1118 {
1119 if ((cr - base) < already - 1)
1120 {
1121 /* \r and presumed \n already within what we have; probably not
1122 actually proxy protocol, but abort cleanly. */
1123 return 0;
1124 }
1125 /* \r is last character read, just need one more. */
1126 last = 1;
1127 }
1128
1129 while (capacity > 0)
1130 {
1131 do { ret = recv(fd, to, 1, 0); } while (ret == -1 && errno == EINTR);
1132 if (ret == -1)
1133 return -1;
1134 have++;
1135 if (last)
1136 return have;
1137 if (*to == '\r')
1138 last = 1;
1139 capacity--;
1140 to++;
1141 }
1142
1143 /* reached end without having room for a final newline, abort */
1144 errno = EOVERFLOW;
1145 return -1;
1146 }
1147
1148 /*************************************************
1149 * Setup host for proxy protocol *
1150 *************************************************/
1151 /* The function configures the connection based on a header from the
1152 inbound host to use Proxy Protocol. The specification is very exact
1153 so exit with an error if do not find the exact required pieces. This
1154 includes an incorrect number of spaces separating args.
1155
1156 Arguments: none
1157 Returns: Boolean success
1158 */
1159
1160 static void
1161 setup_proxy_protocol_host()
1162 {
1163 union {
1164 struct {
1165 uschar line[108];
1166 } v1;
1167 struct {
1168 uschar sig[12];
1169 uint8_t ver_cmd;
1170 uint8_t fam;
1171 uint16_t len;
1172 union {
1173 struct { /* TCP/UDP over IPv4, len = 12 */
1174 uint32_t src_addr;
1175 uint32_t dst_addr;
1176 uint16_t src_port;
1177 uint16_t dst_port;
1178 } ip4;
1179 struct { /* TCP/UDP over IPv6, len = 36 */
1180 uint8_t src_addr[16];
1181 uint8_t dst_addr[16];
1182 uint16_t src_port;
1183 uint16_t dst_port;
1184 } ip6;
1185 struct { /* AF_UNIX sockets, len = 216 */
1186 uschar src_addr[108];
1187 uschar dst_addr[108];
1188 } unx;
1189 } addr;
1190 } v2;
1191 } hdr;
1192
1193 /* Temp variables used in PPv2 address:port parsing */
1194 uint16_t tmpport;
1195 char tmpip[INET_ADDRSTRLEN];
1196 struct sockaddr_in tmpaddr;
1197 char tmpip6[INET6_ADDRSTRLEN];
1198 struct sockaddr_in6 tmpaddr6;
1199
1200 /* We can't read "all data until end" because while SMTP is
1201 server-speaks-first, the TLS handshake is client-speaks-first, so for
1202 TLS-on-connect ports the proxy protocol header will usually be immediately
1203 followed by a TLS handshake, and with N TLS libraries, we can't reliably
1204 reinject data for reading by those. So instead we first read "enough to be
1205 safely read within the header, and figure out how much more to read".
1206 For v1 we will later read to the end-of-line, for v2 we will read based upon
1207 the stated length.
1208
1209 The v2 sig is 12 octets, and another 4 gets us the length, so we know how much
1210 data is needed total. For v1, where the line looks like:
1211 PROXY TCPn L3src L3dest SrcPort DestPort \r\n
1212
1213 However, for v1 there's also `PROXY UNKNOWN\r\n` which is only 15 octets.
1214 We seem to support that. So, if we read 14 octets then we can tell if we're
1215 v2 or v1. If we're v1, we can continue reading as normal.
1216
1217 If we're v2, we can't slurp up the entire header. We need the length in the
1218 15th & 16th octets, then to read everything after that.
1219
1220 So to safely handle v1 and v2, with client-sent-first supported correctly,
1221 we have to do a minimum of 3 read calls, not 1. Eww.
1222 */
1223
1224 #define PROXY_INITIAL_READ 14
1225 #define PROXY_V2_HEADER_SIZE 16
1226 #if PROXY_INITIAL_READ > PROXY_V2_HEADER_SIZE
1227 # error Code bug in sizes of data to read for proxy usage
1228 #endif
1229
1230 int get_ok = 0;
1231 int size, ret;
1232 int fd = fileno(smtp_in);
1233 const char v2sig[12] = "\x0D\x0A\x0D\x0A\x00\x0D\x0A\x51\x55\x49\x54\x0A";
1234 uschar * iptype; /* To display debug info */
1235 struct timeval tv;
1236 struct timeval tvtmp;
1237 socklen_t vslen = sizeof(struct timeval);
1238 BOOL yield = FALSE;
1239
1240 /* Save current socket timeout values */
1241 get_ok = getsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, CS &tvtmp, &vslen);
1242
1243 /* Proxy Protocol host must send header within a short time
1244 (default 3 seconds) or it's considered invalid */
1245 tv.tv_sec = PROXY_NEGOTIATION_TIMEOUT_SEC;
1246 tv.tv_usec = PROXY_NEGOTIATION_TIMEOUT_USEC;
1247 if (setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, CS &tv, sizeof(tv)) < 0)
1248 goto bad;
1249
1250 do
1251 {
1252 /* The inbound host was declared to be a Proxy Protocol host, so
1253 don't do a PEEK into the data, actually slurp up enough to be
1254 "safe". Can't take it all because TLS-on-connect clients follow
1255 immediately with TLS handshake. */
1256 ret = recv(fd, &hdr, PROXY_INITIAL_READ, 0);
1257 }
1258 while (ret == -1 && errno == EINTR);
1259
1260 if (ret == -1)
1261 goto proxyfail;
1262
1263 /* For v2, handle reading the length, and then the rest. */
1264 if ((ret == PROXY_INITIAL_READ) && (memcmp(&hdr.v2, v2sig, sizeof(v2sig)) == 0))
1265 {
1266 int retmore;
1267 uint8_t ver;
1268
1269 /* First get the length fields. */
1270 do
1271 {
1272 retmore = recv(fd, (uschar*)&hdr + ret, PROXY_V2_HEADER_SIZE - PROXY_INITIAL_READ, 0);
1273 } while (retmore == -1 && errno == EINTR);
1274 if (retmore == -1)
1275 goto proxyfail;
1276 ret += retmore;
1277
1278 ver = (hdr.v2.ver_cmd & 0xf0) >> 4;
1279
1280 /* May 2014: haproxy combined the version and command into one byte to
1281 allow two full bytes for the length field in order to proxy SSL
1282 connections. SSL Proxy is not supported in this version of Exim, but
1283 must still separate values here. */
1284
1285 if (ver != 0x02)
1286 {
1287 DEBUG(D_receive) debug_printf("Invalid Proxy Protocol version: %d\n", ver);
1288 goto proxyfail;
1289 }
1290
1291 /* The v2 header will always be 16 bytes per the spec. */
1292 size = 16 + ntohs(hdr.v2.len);
1293 DEBUG(D_receive) debug_printf("Detected PROXYv2 header, size %d (limit %d)\n",
1294 size, (int)sizeof(hdr));
1295
1296 /* We should now have 16 octets (PROXY_V2_HEADER_SIZE), and we know the total
1297 amount that we need. Double-check that the size is not unreasonable, then
1298 get the rest. */
1299 if (size > sizeof(hdr))
1300 {
1301 DEBUG(D_receive) debug_printf("PROXYv2 header size unreasonably large; security attack?\n");
1302 goto proxyfail;
1303 }
1304
1305 do
1306 {
1307 do
1308 {
1309 retmore = recv(fd, (uschar*)&hdr + ret, size-ret, 0);
1310 } while (retmore == -1 && errno == EINTR);
1311 if (retmore == -1)
1312 goto proxyfail;
1313 ret += retmore;
1314 DEBUG(D_receive) debug_printf("PROXYv2: have %d/%d required octets\n", ret, size);
1315 } while (ret < size);
1316
1317 } /* end scope for getting rest of data for v2 */
1318
1319 /* At this point: if PROXYv2, we've read the exact size required for all data;
1320 if PROXYv1 then we've read "less than required for any valid line" and should
1321 read the rest". */
1322
1323 if (ret >= 16 && memcmp(&hdr.v2, v2sig, 12) == 0)
1324 {
1325 uint8_t cmd = (hdr.v2.ver_cmd & 0x0f);
1326
1327 switch (cmd)
1328 {
1329 case 0x01: /* PROXY command */
1330 switch (hdr.v2.fam)
1331 {
1332 case 0x11: /* TCPv4 address type */
1333 iptype = US"IPv4";
1334 tmpaddr.sin_addr.s_addr = hdr.v2.addr.ip4.src_addr;
1335 inet_ntop(AF_INET, &tmpaddr.sin_addr, CS &tmpip, sizeof(tmpip));
1336 if (!string_is_ip_address(US tmpip, NULL))
1337 {
1338 DEBUG(D_receive) debug_printf("Invalid %s source IP\n", iptype);
1339 goto proxyfail;
1340 }
1341 proxy_local_address = sender_host_address;
1342 sender_host_address = string_copy(US tmpip);
1343 tmpport = ntohs(hdr.v2.addr.ip4.src_port);
1344 proxy_local_port = sender_host_port;
1345 sender_host_port = tmpport;
1346 /* Save dest ip/port */
1347 tmpaddr.sin_addr.s_addr = hdr.v2.addr.ip4.dst_addr;
1348 inet_ntop(AF_INET, &tmpaddr.sin_addr, CS &tmpip, sizeof(tmpip));
1349 if (!string_is_ip_address(US tmpip, NULL))
1350 {
1351 DEBUG(D_receive) debug_printf("Invalid %s dest port\n", iptype);
1352 goto proxyfail;
1353 }
1354 proxy_external_address = string_copy(US tmpip);
1355 tmpport = ntohs(hdr.v2.addr.ip4.dst_port);
1356 proxy_external_port = tmpport;
1357 goto done;
1358 case 0x21: /* TCPv6 address type */
1359 iptype = US"IPv6";
1360 memmove(tmpaddr6.sin6_addr.s6_addr, hdr.v2.addr.ip6.src_addr, 16);
1361 inet_ntop(AF_INET6, &tmpaddr6.sin6_addr, CS &tmpip6, sizeof(tmpip6));
1362 if (!string_is_ip_address(US tmpip6, NULL))
1363 {
1364 DEBUG(D_receive) debug_printf("Invalid %s source IP\n", iptype);
1365 goto proxyfail;
1366 }
1367 proxy_local_address = sender_host_address;
1368 sender_host_address = string_copy(US tmpip6);
1369 tmpport = ntohs(hdr.v2.addr.ip6.src_port);
1370 proxy_local_port = sender_host_port;
1371 sender_host_port = tmpport;
1372 /* Save dest ip/port */
1373 memmove(tmpaddr6.sin6_addr.s6_addr, hdr.v2.addr.ip6.dst_addr, 16);
1374 inet_ntop(AF_INET6, &tmpaddr6.sin6_addr, CS &tmpip6, sizeof(tmpip6));
1375 if (!string_is_ip_address(US tmpip6, NULL))
1376 {
1377 DEBUG(D_receive) debug_printf("Invalid %s dest port\n", iptype);
1378 goto proxyfail;
1379 }
1380 proxy_external_address = string_copy(US tmpip6);
1381 tmpport = ntohs(hdr.v2.addr.ip6.dst_port);
1382 proxy_external_port = tmpport;
1383 goto done;
1384 default:
1385 DEBUG(D_receive)
1386 debug_printf("Unsupported PROXYv2 connection type: 0x%02x\n",
1387 hdr.v2.fam);
1388 goto proxyfail;
1389 }
1390 /* Unsupported protocol, keep local connection address */
1391 break;
1392 case 0x00: /* LOCAL command */
1393 /* Keep local connection address for LOCAL */
1394 iptype = US"local";
1395 break;
1396 default:
1397 DEBUG(D_receive)
1398 debug_printf("Unsupported PROXYv2 command: 0x%x\n", cmd);
1399 goto proxyfail;
1400 }
1401 }
1402 else if (ret >= 8 && memcmp(hdr.v1.line, "PROXY", 5) == 0)
1403 {
1404 uschar *p;
1405 uschar *end;
1406 uschar *sp; /* Utility variables follow */
1407 int tmp_port;
1408 int r2;
1409 char *endc;
1410
1411 /* get the rest of the line */
1412 r2 = swallow_until_crlf(fd, (uschar*)&hdr, ret, sizeof(hdr)-ret);
1413 if (r2 == -1)
1414 goto proxyfail;
1415 ret += r2;
1416
1417 p = string_copy(hdr.v1.line);
1418 end = memchr(p, '\r', ret - 1);
1419
1420 if (!end || (end == (uschar*)&hdr + ret) || end[1] != '\n')
1421 {
1422 DEBUG(D_receive) debug_printf("Partial or invalid PROXY header\n");
1423 goto proxyfail;
1424 }
1425 *end = '\0'; /* Terminate the string */
1426 size = end + 2 - p; /* Skip header + CRLF */
1427 DEBUG(D_receive) debug_printf("Detected PROXYv1 header\n");
1428 DEBUG(D_receive) debug_printf("Bytes read not within PROXY header: %d\n", ret - size);
1429 /* Step through the string looking for the required fields. Ensure
1430 strict adherence to required formatting, exit for any error. */
1431 p += 5;
1432 if (!isspace(*(p++)))
1433 {
1434 DEBUG(D_receive) debug_printf("Missing space after PROXY command\n");
1435 goto proxyfail;
1436 }
1437 if (!Ustrncmp(p, CCS"TCP4", 4))
1438 iptype = US"IPv4";
1439 else if (!Ustrncmp(p,CCS"TCP6", 4))
1440 iptype = US"IPv6";
1441 else if (!Ustrncmp(p,CCS"UNKNOWN", 7))
1442 {
1443 iptype = US"Unknown";
1444 goto done;
1445 }
1446 else
1447 {
1448 DEBUG(D_receive) debug_printf("Invalid TCP type\n");
1449 goto proxyfail;
1450 }
1451
1452 p += Ustrlen(iptype);
1453 if (!isspace(*(p++)))
1454 {
1455 DEBUG(D_receive) debug_printf("Missing space after TCP4/6 command\n");
1456 goto proxyfail;
1457 }
1458 /* Find the end of the arg */
1459 if ((sp = Ustrchr(p, ' ')) == NULL)
1460 {
1461 DEBUG(D_receive)
1462 debug_printf("Did not find proxied src %s\n", iptype);
1463 goto proxyfail;
1464 }
1465 *sp = '\0';
1466 if(!string_is_ip_address(p, NULL))
1467 {
1468 DEBUG(D_receive)
1469 debug_printf("Proxied src arg is not an %s address\n", iptype);
1470 goto proxyfail;
1471 }
1472 proxy_local_address = sender_host_address;
1473 sender_host_address = p;
1474 p = sp + 1;
1475 if ((sp = Ustrchr(p, ' ')) == NULL)
1476 {
1477 DEBUG(D_receive)
1478 debug_printf("Did not find proxy dest %s\n", iptype);
1479 goto proxyfail;
1480 }
1481 *sp = '\0';
1482 if(!string_is_ip_address(p, NULL))
1483 {
1484 DEBUG(D_receive)
1485 debug_printf("Proxy dest arg is not an %s address\n", iptype);
1486 goto proxyfail;
1487 }
1488 proxy_external_address = p;
1489 p = sp + 1;
1490 if ((sp = Ustrchr(p, ' ')) == NULL)
1491 {
1492 DEBUG(D_receive) debug_printf("Did not find proxied src port\n");
1493 goto proxyfail;
1494 }
1495 *sp = '\0';
1496 tmp_port = strtol(CCS p, &endc, 10);
1497 if (*endc || tmp_port == 0)
1498 {
1499 DEBUG(D_receive)
1500 debug_printf("Proxied src port '%s' not an integer\n", p);
1501 goto proxyfail;
1502 }
1503 proxy_local_port = sender_host_port;
1504 sender_host_port = tmp_port;
1505 p = sp + 1;
1506 if ((sp = Ustrchr(p, '\0')) == NULL)
1507 {
1508 DEBUG(D_receive) debug_printf("Did not find proxy dest port\n");
1509 goto proxyfail;
1510 }
1511 tmp_port = strtol(CCS p, &endc, 10);
1512 if (*endc || tmp_port == 0)
1513 {
1514 DEBUG(D_receive)
1515 debug_printf("Proxy dest port '%s' not an integer\n", p);
1516 goto proxyfail;
1517 }
1518 proxy_external_port = tmp_port;
1519 /* Already checked for /r /n above. Good V1 header received. */
1520 }
1521 else
1522 {
1523 /* Wrong protocol */
1524 DEBUG(D_receive) debug_printf("Invalid proxy protocol version negotiation\n");
1525 (void) swallow_until_crlf(fd, (uschar*)&hdr, ret, sizeof(hdr)-ret);
1526 goto proxyfail;
1527 }
1528
1529 done:
1530 DEBUG(D_receive)
1531 debug_printf("Valid %s sender from Proxy Protocol header\n", iptype);
1532 yield = proxy_session;
1533
1534 /* Don't flush any potential buffer contents. Any input on proxyfail
1535 should cause a synchronization failure */
1536
1537 proxyfail:
1538 restore_socket_timeout(fd, get_ok, &tvtmp, vslen);
1539
1540 bad:
1541 if (yield)
1542 {
1543 sender_host_name = NULL;
1544 (void) host_name_lookup();
1545 host_build_sender_fullhost();
1546 }
1547 else
1548 {
1549 f.proxy_session_failed = TRUE;
1550 DEBUG(D_receive)
1551 debug_printf("Failure to extract proxied host, only QUIT allowed\n");
1552 }
1553
1554 return;
1555 }
1556 #endif
1557
1558 /*************************************************
1559 * Read one command line *
1560 *************************************************/
1561
1562 /* Strictly, SMTP commands coming over the net are supposed to end with CRLF.
1563 There are sites that don't do this, and in any case internal SMTP probably
1564 should check only for LF. Consequently, we check here for LF only. The line
1565 ends up with [CR]LF removed from its end. If we get an overlong line, treat as
1566 an unknown command. The command is read into the global smtp_cmd_buffer so that
1567 it is available via $smtp_command.
1568
1569 The character reading routine sets up a timeout for each block actually read
1570 from the input (which may contain more than one command). We set up a special
1571 signal handler that closes down the session on a timeout. Control does not
1572 return when it runs.
1573
1574 Arguments:
1575 check_sync if TRUE, check synchronization rules if global option is TRUE
1576 buffer_lim maximum to buffer in lower layer
1577
1578 Returns: a code identifying the command (enumerated above)
1579 */
1580
1581 static int
1582 smtp_read_command(BOOL check_sync, unsigned buffer_lim)
1583 {
1584 int c;
1585 int ptr = 0;
1586 BOOL hadnull = FALSE;
1587
1588 had_command_timeout = 0;
1589 os_non_restarting_signal(SIGALRM, command_timeout_handler);
1590
1591 while ((c = (receive_getc)(buffer_lim)) != '\n' && c != EOF)
1592 {
1593 if (ptr >= SMTP_CMD_BUFFER_SIZE)
1594 {
1595 os_non_restarting_signal(SIGALRM, sigalrm_handler);
1596 return OTHER_CMD;
1597 }
1598 if (c == 0)
1599 {
1600 hadnull = TRUE;
1601 c = '?';
1602 }
1603 smtp_cmd_buffer[ptr++] = c;
1604 }
1605
1606 receive_linecount++; /* For BSMTP errors */
1607 os_non_restarting_signal(SIGALRM, sigalrm_handler);
1608
1609 /* If hit end of file, return pseudo EOF command. Whether we have a
1610 part-line already read doesn't matter, since this is an error state. */
1611
1612 if (c == EOF) return EOF_CMD;
1613
1614 /* Remove any CR and white space at the end of the line, and terminate the
1615 string. */
1616
1617 while (ptr > 0 && isspace(smtp_cmd_buffer[ptr-1])) ptr--;
1618 smtp_cmd_buffer[ptr] = 0;
1619
1620 DEBUG(D_receive) debug_printf("SMTP<< %s\n", smtp_cmd_buffer);
1621
1622 /* NULLs are not allowed in SMTP commands */
1623
1624 if (hadnull) return BADCHAR_CMD;
1625
1626 /* Scan command list and return identity, having set the data pointer
1627 to the start of the actual data characters. Check for SMTP synchronization
1628 if required. */
1629
1630 for (smtp_cmd_list * p = cmd_list; p < cmd_list_end; p++)
1631 {
1632 #ifdef SUPPORT_PROXY
1633 /* Only allow QUIT command if Proxy Protocol parsing failed */
1634 if (proxy_session && f.proxy_session_failed && p->cmd != QUIT_CMD)
1635 continue;
1636 #endif
1637 if ( p->len
1638 && strncmpic(smtp_cmd_buffer, US p->name, p->len) == 0
1639 && ( smtp_cmd_buffer[p->len-1] == ':' /* "mail from:" or "rcpt to:" */
1640 || smtp_cmd_buffer[p->len] == 0
1641 || smtp_cmd_buffer[p->len] == ' '
1642 ) )
1643 {
1644 if (smtp_inptr < smtp_inend && /* Outstanding input */
1645 p->cmd < sync_cmd_limit && /* Command should sync */
1646 check_sync && /* Local flag set */
1647 smtp_enforce_sync && /* Global flag set */
1648 sender_host_address != NULL && /* Not local input */
1649 !f.sender_host_notsocket) /* Really is a socket */
1650 return BADSYN_CMD;
1651
1652 /* The variables $smtp_command and $smtp_command_argument point into the
1653 unmodified input buffer. A copy of the latter is taken for actual
1654 processing, so that it can be chopped up into separate parts if necessary,
1655 for example, when processing a MAIL command options such as SIZE that can
1656 follow the sender address. */
1657
1658 smtp_cmd_argument = smtp_cmd_buffer + p->len;
1659 while (isspace(*smtp_cmd_argument)) smtp_cmd_argument++;
1660 Ustrcpy(smtp_data_buffer, smtp_cmd_argument);
1661 smtp_cmd_data = smtp_data_buffer;
1662
1663 /* Count non-mail commands from those hosts that are controlled in this
1664 way. The default is all hosts. We don't waste effort checking the list
1665 until we get a non-mail command, but then cache the result to save checking
1666 again. If there's a DEFER while checking the host, assume it's in the list.
1667
1668 Note that one instance of RSET, EHLO/HELO, and STARTTLS is allowed at the
1669 start of each incoming message by fiddling with the value in the table. */
1670
1671 if (!p->is_mail_cmd)
1672 {
1673 if (count_nonmail == TRUE_UNSET) count_nonmail =
1674 verify_check_host(&smtp_accept_max_nonmail_hosts) != FAIL;
1675 if (count_nonmail && ++nonmail_command_count > smtp_accept_max_nonmail)
1676 return TOO_MANY_NONMAIL_CMD;
1677 }
1678
1679 /* If there is data for a command that does not expect it, generate the
1680 error here. */
1681
1682 return (p->has_arg || *smtp_cmd_data == 0)? p->cmd : BADARG_CMD;
1683 }
1684 }
1685
1686 #ifdef SUPPORT_PROXY
1687 /* Only allow QUIT command if Proxy Protocol parsing failed */
1688 if (proxy_session && f.proxy_session_failed)
1689 return PROXY_FAIL_IGNORE_CMD;
1690 #endif
1691
1692 /* Enforce synchronization for unknown commands */
1693
1694 if ( smtp_inptr < smtp_inend /* Outstanding input */
1695 && check_sync /* Local flag set */
1696 && smtp_enforce_sync /* Global flag set */
1697 && sender_host_address /* Not local input */
1698 && !f.sender_host_notsocket) /* Really is a socket */
1699 return BADSYN_CMD;
1700
1701 return OTHER_CMD;
1702 }
1703
1704
1705
1706 /*************************************************
1707 * Forced closedown of call *
1708 *************************************************/
1709
1710 /* This function is called from log.c when Exim is dying because of a serious
1711 disaster, and also from some other places. If an incoming non-batched SMTP
1712 channel is open, it swallows the rest of the incoming message if in the DATA
1713 phase, sends the reply string, and gives an error to all subsequent commands
1714 except QUIT. The existence of an SMTP call is detected by the non-NULLness of
1715 smtp_in.
1716
1717 Arguments:
1718 message SMTP reply string to send, excluding the code
1719
1720 Returns: nothing
1721 */
1722
1723 void
1724 smtp_closedown(uschar *message)
1725 {
1726 if (!smtp_in || smtp_batched_input) return;
1727 receive_swallow_smtp();
1728 smtp_printf("421 %s\r\n", FALSE, message);
1729
1730 for (;;) switch(smtp_read_command(FALSE, GETC_BUFFER_UNLIMITED))
1731 {
1732 case EOF_CMD:
1733 return;
1734
1735 case QUIT_CMD:
1736 smtp_printf("221 %s closing connection\r\n", FALSE, smtp_active_hostname);
1737 mac_smtp_fflush();
1738 return;
1739
1740 case RSET_CMD:
1741 smtp_printf("250 Reset OK\r\n", FALSE);
1742 break;
1743
1744 default:
1745 smtp_printf("421 %s\r\n", FALSE, message);
1746 break;
1747 }
1748 }
1749
1750
1751
1752
1753 /*************************************************
1754 * Set up connection info for logging *
1755 *************************************************/
1756
1757 /* This function is called when logging information about an SMTP connection.
1758 It sets up appropriate source information, depending on the type of connection.
1759 If sender_fullhost is NULL, we are at a very early stage of the connection;
1760 just use the IP address.
1761
1762 Argument: none
1763 Returns: a string describing the connection
1764 */
1765
1766 uschar *
1767 smtp_get_connection_info(void)
1768 {
1769 const uschar * hostname = sender_fullhost
1770 ? sender_fullhost : sender_host_address;
1771
1772 if (host_checking)
1773 return string_sprintf("SMTP connection from %s", hostname);
1774
1775 if (f.sender_host_unknown || f.sender_host_notsocket)
1776 return string_sprintf("SMTP connection from %s", sender_ident);
1777
1778 if (f.is_inetd)
1779 return string_sprintf("SMTP connection from %s (via inetd)", hostname);
1780
1781 if (LOGGING(incoming_interface) && interface_address)
1782 return string_sprintf("SMTP connection from %s I=[%s]:%d", hostname,
1783 interface_address, interface_port);
1784
1785 return string_sprintf("SMTP connection from %s", hostname);
1786 }
1787
1788
1789
1790 #ifndef DISABLE_TLS
1791 /* Append TLS-related information to a log line
1792
1793 Arguments:
1794 g String under construction: allocated string to extend, or NULL
1795
1796 Returns: Allocated string or NULL
1797 */
1798 static gstring *
1799 s_tlslog(gstring * g)
1800 {
1801 if (LOGGING(tls_cipher) && tls_in.cipher)
1802 {
1803 g = string_append(g, 2, US" X=", tls_in.cipher);
1804 #ifdef EXPERIMENTAL_TLS_RESUME
1805 if (LOGGING(tls_resumption) && tls_in.resumption & RESUME_USED)
1806 g = string_catn(g, US"*", 1);
1807 #endif
1808 }
1809 if (LOGGING(tls_certificate_verified) && tls_in.cipher)
1810 g = string_append(g, 2, US" CV=", tls_in.certificate_verified? "yes":"no");
1811 if (LOGGING(tls_peerdn) && tls_in.peerdn)
1812 g = string_append(g, 3, US" DN=\"", string_printing(tls_in.peerdn), US"\"");
1813 if (LOGGING(tls_sni) && tls_in.sni)
1814 g = string_append(g, 3, US" SNI=\"", string_printing(tls_in.sni), US"\"");
1815 return g;
1816 }
1817 #endif
1818
1819 /*************************************************
1820 * Log lack of MAIL if so configured *
1821 *************************************************/
1822
1823 /* This function is called when an SMTP session ends. If the log selector
1824 smtp_no_mail is set, write a log line giving some details of what has happened
1825 in the SMTP session.
1826
1827 Arguments: none
1828 Returns: nothing
1829 */
1830
1831 void
1832 smtp_log_no_mail(void)
1833 {
1834 uschar * sep, * s;
1835 gstring * g = NULL;
1836
1837 if (smtp_mailcmd_count > 0 || !LOGGING(smtp_no_mail))
1838 return;
1839
1840 if (sender_host_authenticated)
1841 {
1842 g = string_append(g, 2, US" A=", sender_host_authenticated);
1843 if (authenticated_id) g = string_append(g, 2, US":", authenticated_id);
1844 }
1845
1846 #ifndef DISABLE_TLS
1847 g = s_tlslog(g);
1848 #endif
1849
1850 sep = smtp_connection_had[SMTP_HBUFF_SIZE-1] != SCH_NONE ? US" C=..." : US" C=";
1851
1852 for (int i = smtp_ch_index; i < SMTP_HBUFF_SIZE; i++)
1853 if (smtp_connection_had[i] != SCH_NONE)
1854 {
1855 g = string_append(g, 2, sep, smtp_names[smtp_connection_had[i]]);
1856 sep = US",";
1857 }
1858
1859 for (int i = 0; i < smtp_ch_index; i++)
1860 {
1861 g = string_append(g, 2, sep, smtp_names[smtp_connection_had[i]]);
1862 sep = US",";
1863 }
1864
1865 if (!(s = string_from_gstring(g))) s = US"";
1866
1867 log_write(0, LOG_MAIN, "no MAIL in %sSMTP connection from %s D=%s%s",
1868 f.tcp_in_fastopen ? f.tcp_in_fastopen_data ? US"TFO* " : US"TFO " : US"",
1869 host_and_ident(FALSE), string_timesince(&smtp_connection_start), s);
1870 }
1871
1872
1873 /* Return list of recent smtp commands */
1874
1875 uschar *
1876 smtp_cmd_hist(void)
1877 {
1878 gstring * list = NULL;
1879 uschar * s;
1880
1881 for (int i = smtp_ch_index; i < SMTP_HBUFF_SIZE; i++)
1882 if (smtp_connection_had[i] != SCH_NONE)
1883 list = string_append_listele(list, ',', smtp_names[smtp_connection_had[i]]);
1884
1885 for (int i = 0; i < smtp_ch_index; i++)
1886 list = string_append_listele(list, ',', smtp_names[smtp_connection_had[i]]);
1887
1888 s = string_from_gstring(list);
1889 return s ? s : US"";
1890 }
1891
1892
1893
1894
1895 /*************************************************
1896 * Check HELO line and set sender_helo_name *
1897 *************************************************/
1898
1899 /* Check the format of a HELO line. The data for HELO/EHLO is supposed to be
1900 the domain name of the sending host, or an ip literal in square brackets. The
1901 argument is placed in sender_helo_name, which is in malloc store, because it
1902 must persist over multiple incoming messages. If helo_accept_junk is set, this
1903 host is permitted to send any old junk (needed for some broken hosts).
1904 Otherwise, helo_allow_chars can be used for rogue characters in general
1905 (typically people want to let in underscores).
1906
1907 Argument:
1908 s the data portion of the line (already past any white space)
1909
1910 Returns: TRUE or FALSE
1911 */
1912
1913 static BOOL
1914 check_helo(uschar *s)
1915 {
1916 uschar *start = s;
1917 uschar *end = s + Ustrlen(s);
1918 BOOL yield = fl.helo_accept_junk;
1919
1920 /* Discard any previous helo name */
1921
1922 sender_helo_name = NULL;
1923
1924 /* Skip tests if junk is permitted. */
1925
1926 if (!yield)
1927
1928 /* Allow the new standard form for IPv6 address literals, namely,
1929 [IPv6:....], and because someone is bound to use it, allow an equivalent
1930 IPv4 form. Allow plain addresses as well. */
1931
1932 if (*s == '[')
1933 {
1934 if (end[-1] == ']')
1935 {
1936 end[-1] = 0;
1937 if (strncmpic(s, US"[IPv6:", 6) == 0)
1938 yield = (string_is_ip_address(s+6, NULL) == 6);
1939 else if (strncmpic(s, US"[IPv4:", 6) == 0)
1940 yield = (string_is_ip_address(s+6, NULL) == 4);
1941 else
1942 yield = (string_is_ip_address(s+1, NULL) != 0);
1943 end[-1] = ']';
1944 }
1945 }
1946
1947 /* Non-literals must be alpha, dot, hyphen, plus any non-valid chars
1948 that have been configured (usually underscore - sigh). */
1949
1950 else if (*s)
1951 for (yield = TRUE; *s; s++)
1952 if (!isalnum(*s) && *s != '.' && *s != '-' &&
1953 Ustrchr(helo_allow_chars, *s) == NULL)
1954 {
1955 yield = FALSE;
1956 break;
1957 }
1958
1959 /* Save argument if OK */
1960
1961 if (yield) sender_helo_name = string_copy_perm(start, TRUE);
1962 return yield;
1963 }
1964
1965
1966
1967
1968
1969 /*************************************************
1970 * Extract SMTP command option *
1971 *************************************************/
1972
1973 /* This function picks the next option setting off the end of smtp_cmd_data. It
1974 is called for MAIL FROM and RCPT TO commands, to pick off the optional ESMTP
1975 things that can appear there.
1976
1977 Arguments:
1978 name point this at the name
1979 value point this at the data string
1980
1981 Returns: TRUE if found an option
1982 */
1983
1984 static BOOL
1985 extract_option(uschar **name, uschar **value)
1986 {
1987 uschar *n;
1988 uschar *v = smtp_cmd_data + Ustrlen(smtp_cmd_data) - 1;
1989 while (isspace(*v)) v--;
1990 v[1] = 0;
1991 while (v > smtp_cmd_data && *v != '=' && !isspace(*v))
1992 {
1993 /* Take care to not stop at a space embedded in a quoted local-part */
1994
1995 if (*v == '"') do v--; while (*v != '"' && v > smtp_cmd_data+1);
1996 v--;
1997 }
1998
1999 n = v;
2000 if (*v == '=')
2001 {
2002 while(isalpha(n[-1])) n--;
2003 /* RFC says SP, but TAB seen in wild and other major MTAs accept it */
2004 if (!isspace(n[-1])) return FALSE;
2005 n[-1] = 0;
2006 }
2007 else
2008 {
2009 n++;
2010 if (v == smtp_cmd_data) return FALSE;
2011 }
2012 *v++ = 0;
2013 *name = n;
2014 *value = v;
2015 return TRUE;
2016 }
2017
2018
2019
2020
2021
2022 /*************************************************
2023 * Reset for new message *
2024 *************************************************/
2025
2026 /* This function is called whenever the SMTP session is reset from
2027 within either of the setup functions; also from the daemon loop.
2028
2029 Argument: the stacking pool storage reset point
2030 Returns: nothing
2031 */
2032
2033 void *
2034 smtp_reset(void *reset_point)
2035 {
2036 recipients_list = NULL;
2037 rcpt_count = rcpt_defer_count = rcpt_fail_count =
2038 raw_recipients_count = recipients_count = recipients_list_max = 0;
2039 message_linecount = 0;
2040 message_size = -1;
2041 acl_added_headers = NULL;
2042 acl_removed_headers = NULL;
2043 f.queue_only_policy = FALSE;
2044 rcpt_smtp_response = NULL;
2045 fl.rcpt_smtp_response_same = TRUE;
2046 fl.rcpt_in_progress = FALSE;
2047 f.deliver_freeze = FALSE; /* Can be set by ACL */
2048 freeze_tell = freeze_tell_config; /* Can be set by ACL */
2049 fake_response = OK; /* Can be set by ACL */
2050 #ifdef WITH_CONTENT_SCAN
2051 f.no_mbox_unspool = FALSE; /* Can be set by ACL */
2052 #endif
2053 f.submission_mode = FALSE; /* Can be set by ACL */
2054 f.suppress_local_fixups = f.suppress_local_fixups_default; /* Can be set by ACL */
2055 f.active_local_from_check = local_from_check; /* Can be set by ACL */
2056 f.active_local_sender_retain = local_sender_retain; /* Can be set by ACL */
2057 sending_ip_address = NULL;
2058 return_path = sender_address = NULL;
2059 sender_data = NULL; /* Can be set by ACL */
2060 deliver_localpart_parent = deliver_localpart_orig = NULL;
2061 deliver_domain_parent = deliver_domain_orig = NULL;
2062 callout_address = NULL;
2063 submission_name = NULL; /* Can be set by ACL */
2064 raw_sender = NULL; /* After SMTP rewrite, before qualifying */
2065 sender_address_unrewritten = NULL; /* Set only after verify rewrite */
2066 sender_verified_list = NULL; /* No senders verified */
2067 memset(sender_address_cache, 0, sizeof(sender_address_cache));
2068 memset(sender_domain_cache, 0, sizeof(sender_domain_cache));
2069
2070 authenticated_sender = NULL;
2071 #ifdef EXPERIMENTAL_BRIGHTMAIL
2072 bmi_run = 0;
2073 bmi_verdicts = NULL;
2074 #endif
2075 dnslist_domain = dnslist_matched = NULL;
2076 #ifdef SUPPORT_SPF
2077 spf_header_comment = spf_received = spf_result = spf_smtp_comment = NULL;
2078 spf_result_guessed = FALSE;
2079 #endif
2080 #ifndef DISABLE_DKIM
2081 dkim_cur_signer = dkim_signers =
2082 dkim_signing_domain = dkim_signing_selector = dkim_signatures = NULL;
2083 dkim_cur_signer = dkim_signers = dkim_signing_domain = dkim_signing_selector = NULL;
2084 f.dkim_disable_verify = FALSE;
2085 dkim_collect_input = 0;
2086 dkim_verify_overall = dkim_verify_status = dkim_verify_reason = NULL;
2087 dkim_key_length = 0;
2088 #endif
2089 #ifdef SUPPORT_DMARC
2090 f.dmarc_has_been_checked = f.dmarc_disable_verify = f.dmarc_enable_forensic = FALSE;
2091 dmarc_domain_policy = dmarc_status = dmarc_status_text =
2092 dmarc_used_domain = NULL;
2093 #endif
2094 #ifdef EXPERIMENTAL_ARC
2095 arc_state = arc_state_reason = NULL;
2096 arc_received_instance = 0;
2097 #endif
2098 dsn_ret = 0;
2099 dsn_envid = NULL;
2100 deliver_host = deliver_host_address = NULL; /* Can be set by ACL */
2101 #ifndef DISABLE_PRDR
2102 prdr_requested = FALSE;
2103 #endif
2104 #ifdef SUPPORT_I18N
2105 message_smtputf8 = FALSE;
2106 #endif
2107 body_linecount = body_zerocount = 0;
2108
2109 sender_rate = sender_rate_limit = sender_rate_period = NULL;
2110 ratelimiters_mail = NULL; /* Updated by ratelimit ACL condition */
2111 /* Note that ratelimiters_conn persists across resets. */
2112
2113 /* Reset message ACL variables */
2114
2115 acl_var_m = NULL;
2116
2117 /* The message body variables use malloc store. They may be set if this is
2118 not the first message in an SMTP session and the previous message caused them
2119 to be referenced in an ACL. */
2120
2121 if (message_body)
2122 {
2123 store_free(message_body);
2124 message_body = NULL;
2125 }
2126
2127 if (message_body_end)
2128 {
2129 store_free(message_body_end);
2130 message_body_end = NULL;
2131 }
2132
2133 /* Warning log messages are also saved in malloc store. They are saved to avoid
2134 repetition in the same message, but it seems right to repeat them for different
2135 messages. */
2136
2137 while (acl_warn_logged)
2138 {
2139 string_item *this = acl_warn_logged;
2140 acl_warn_logged = acl_warn_logged->next;
2141 store_free(this);
2142 }
2143 store_reset(reset_point);
2144 return store_mark();
2145 }
2146
2147
2148
2149
2150
2151 /*************************************************
2152 * Initialize for incoming batched SMTP message *
2153 *************************************************/
2154
2155 /* This function is called from smtp_setup_msg() in the case when
2156 smtp_batched_input is true. This happens when -bS is used to pass a whole batch
2157 of messages in one file with SMTP commands between them. All errors must be
2158 reported by sending a message, and only MAIL FROM, RCPT TO, and DATA are
2159 relevant. After an error on a sender, or an invalid recipient, the remainder
2160 of the message is skipped. The value of received_protocol is already set.
2161
2162 Argument: none
2163 Returns: > 0 message successfully started (reached DATA)
2164 = 0 QUIT read or end of file reached
2165 < 0 should not occur
2166 */
2167
2168 static int
2169 smtp_setup_batch_msg(void)
2170 {
2171 int done = 0;
2172 rmark reset_point = store_mark();
2173
2174 /* Save the line count at the start of each transaction - single commands
2175 like HELO and RSET count as whole transactions. */
2176
2177 bsmtp_transaction_linecount = receive_linecount;
2178
2179 if ((receive_feof)()) return 0; /* Treat EOF as QUIT */
2180
2181 cancel_cutthrough_connection(TRUE, US"smtp_setup_batch_msg");
2182 reset_point = smtp_reset(reset_point); /* Reset for start of message */
2183
2184 /* Deal with SMTP commands. This loop is exited by setting done to a POSITIVE
2185 value. The values are 2 larger than the required yield of the function. */
2186
2187 while (done <= 0)
2188 {
2189 uschar *errmess;
2190 uschar *recipient = NULL;
2191 int start, end, sender_domain, recipient_domain;
2192
2193 switch(smtp_read_command(FALSE, GETC_BUFFER_UNLIMITED))
2194 {
2195 /* The HELO/EHLO commands set sender_address_helo if they have
2196 valid data; otherwise they are ignored, except that they do
2197 a reset of the state. */
2198
2199 case HELO_CMD:
2200 case EHLO_CMD:
2201
2202 check_helo(smtp_cmd_data);
2203 /* Fall through */
2204
2205 case RSET_CMD:
2206 cancel_cutthrough_connection(TRUE, US"RSET received");
2207 reset_point = smtp_reset(reset_point);
2208 bsmtp_transaction_linecount = receive_linecount;
2209 break;
2210
2211
2212 /* The MAIL FROM command requires an address as an operand. All we
2213 do here is to parse it for syntactic correctness. The form "<>" is
2214 a special case which converts into an empty string. The start/end
2215 pointers in the original are not used further for this address, as
2216 it is the canonical extracted address which is all that is kept. */
2217
2218 case MAIL_CMD:
2219 smtp_mailcmd_count++; /* Count for no-mail log */
2220 if (sender_address != NULL)
2221 /* The function moan_smtp_batch() does not return. */
2222 moan_smtp_batch(smtp_cmd_buffer, "503 Sender already given");
2223
2224 if (smtp_cmd_data[0] == 0)
2225 /* The function moan_smtp_batch() does not return. */
2226 moan_smtp_batch(smtp_cmd_buffer, "501 MAIL FROM must have an address operand");
2227
2228 /* Reset to start of message */
2229
2230 cancel_cutthrough_connection(TRUE, US"MAIL received");
2231 reset_point = smtp_reset(reset_point);
2232
2233 /* Apply SMTP rewrite */
2234
2235 raw_sender = ((rewrite_existflags & rewrite_smtp) != 0)?
2236 rewrite_one(smtp_cmd_data, rewrite_smtp|rewrite_smtp_sender, NULL, FALSE,
2237 US"", global_rewrite_rules) : smtp_cmd_data;
2238
2239 /* Extract the address; the TRUE flag allows <> as valid */
2240
2241 raw_sender =
2242 parse_extract_address(raw_sender, &errmess, &start, &end, &sender_domain,
2243 TRUE);
2244
2245 if (!raw_sender)
2246 /* The function moan_smtp_batch() does not return. */
2247 moan_smtp_batch(smtp_cmd_buffer, "501 %s", errmess);
2248
2249 sender_address = string_copy(raw_sender);
2250
2251 /* Qualify unqualified sender addresses if permitted to do so. */
2252
2253 if ( !sender_domain
2254 && sender_address[0] != 0 && sender_address[0] != '@')
2255 if (f.allow_unqualified_sender)
2256 {
2257 sender_address = rewrite_address_qualify(sender_address, FALSE);
2258 DEBUG(D_receive) debug_printf("unqualified address %s accepted "
2259 "and rewritten\n", raw_sender);
2260 }
2261 /* The function moan_smtp_batch() does not return. */
2262 else
2263 moan_smtp_batch(smtp_cmd_buffer, "501 sender address must contain "
2264 "a domain");
2265 break;
2266
2267
2268 /* The RCPT TO command requires an address as an operand. All we do
2269 here is to parse it for syntactic correctness. There may be any number
2270 of RCPT TO commands, specifying multiple senders. We build them all into
2271 a data structure that is in argc/argv format. The start/end values
2272 given by parse_extract_address are not used, as we keep only the
2273 extracted address. */
2274
2275 case RCPT_CMD:
2276 if (!sender_address)
2277 /* The function moan_smtp_batch() does not return. */
2278 moan_smtp_batch(smtp_cmd_buffer, "503 No sender yet given");
2279
2280 if (smtp_cmd_data[0] == 0)
2281 /* The function moan_smtp_batch() does not return. */
2282 moan_smtp_batch(smtp_cmd_buffer,
2283 "501 RCPT TO must have an address operand");
2284
2285 /* Check maximum number allowed */
2286
2287 if (recipients_max > 0 && recipients_count + 1 > recipients_max)
2288 /* The function moan_smtp_batch() does not return. */
2289 moan_smtp_batch(smtp_cmd_buffer, "%s too many recipients",
2290 recipients_max_reject? "552": "452");
2291
2292 /* Apply SMTP rewrite, then extract address. Don't allow "<>" as a
2293 recipient address */
2294
2295 recipient = rewrite_existflags & rewrite_smtp
2296 ? rewrite_one(smtp_cmd_data, rewrite_smtp, NULL, FALSE, US"",
2297 global_rewrite_rules)
2298 : smtp_cmd_data;
2299
2300 recipient = parse_extract_address(recipient, &errmess, &start, &end,
2301 &recipient_domain, FALSE);
2302
2303 if (!recipient)
2304 /* The function moan_smtp_batch() does not return. */
2305 moan_smtp_batch(smtp_cmd_buffer, "501 %s", errmess);
2306
2307 /* If the recipient address is unqualified, qualify it if permitted. Then
2308 add it to the list of recipients. */
2309
2310 if (!recipient_domain)
2311 if (f.allow_unqualified_recipient)
2312 {
2313 DEBUG(D_receive) debug_printf("unqualified address %s accepted\n",
2314 recipient);
2315 recipient = rewrite_address_qualify(recipient, TRUE);
2316 }
2317 /* The function moan_smtp_batch() does not return. */
2318 else
2319 moan_smtp_batch(smtp_cmd_buffer,
2320 "501 recipient address must contain a domain");
2321
2322 receive_add_recipient(recipient, -1);
2323 break;
2324
2325
2326 /* The DATA command is legal only if it follows successful MAIL FROM
2327 and RCPT TO commands. This function is complete when a valid DATA
2328 command is encountered. */
2329
2330 case DATA_CMD:
2331 if (!sender_address || recipients_count <= 0)
2332 /* The function moan_smtp_batch() does not return. */
2333 if (!sender_address)
2334 moan_smtp_batch(smtp_cmd_buffer,
2335 "503 MAIL FROM:<sender> command must precede DATA");
2336 else
2337 moan_smtp_batch(smtp_cmd_buffer,
2338 "503 RCPT TO:<recipient> must precede DATA");
2339 else
2340 {
2341 done = 3; /* DATA successfully achieved */
2342 message_ended = END_NOTENDED; /* Indicate in middle of message */
2343 }
2344 break;
2345
2346
2347 /* The VRFY, EXPN, HELP, ETRN, and NOOP commands are ignored. */
2348
2349 case VRFY_CMD:
2350 case EXPN_CMD:
2351 case HELP_CMD:
2352 case NOOP_CMD:
2353 case ETRN_CMD:
2354 bsmtp_transaction_linecount = receive_linecount;
2355 break;
2356
2357
2358 case EOF_CMD:
2359 case QUIT_CMD:
2360 done = 2;
2361 break;
2362
2363
2364 case BADARG_CMD:
2365 /* The function moan_smtp_batch() does not return. */
2366 moan_smtp_batch(smtp_cmd_buffer, "501 Unexpected argument data");
2367 break;
2368
2369
2370 case BADCHAR_CMD:
2371 /* The function moan_smtp_batch() does not return. */
2372 moan_smtp_batch(smtp_cmd_buffer, "501 Unexpected NULL in SMTP command");
2373 break;
2374
2375
2376 default:
2377 /* The function moan_smtp_batch() does not return. */
2378 moan_smtp_batch(smtp_cmd_buffer, "500 Command unrecognized");
2379 break;
2380 }
2381 }
2382
2383 return done - 2; /* Convert yield values */
2384 }
2385
2386
2387
2388
2389 #ifndef DISABLE_TLS
2390 static BOOL
2391 smtp_log_tls_fail(uschar * errstr)
2392 {
2393 uschar * conn_info = smtp_get_connection_info();
2394
2395 if (Ustrncmp(conn_info, US"SMTP ", 5) == 0) conn_info += 5;
2396 /* I'd like to get separated H= here, but too hard for now */
2397
2398 log_write(0, LOG_MAIN, "TLS error on %s %s", conn_info, errstr);
2399 return FALSE;
2400 }
2401 #endif
2402
2403
2404
2405
2406 #ifdef TCP_FASTOPEN
2407 static void
2408 tfo_in_check(void)
2409 {
2410 # ifdef __FreeBSD__
2411 int is_fastopen;
2412 socklen_t len = sizeof(is_fastopen);
2413
2414 /* The tinfo TCPOPT_FAST_OPEN bit seems unreliable, and we don't see state
2415 TCP_SYN_RCV (as of 12.1) so no idea about data-use. */
2416
2417 if (getsockopt(fileno(smtp_out), IPPROTO_TCP, TCP_FASTOPEN, &is_fastopen, &len) == 0)
2418 {
2419 if (is_fastopen)
2420 {
2421 DEBUG(D_receive)
2422 debug_printf("TFO mode connection (TCP_FASTOPEN getsockopt)\n");
2423 f.tcp_in_fastopen = TRUE;
2424 }
2425 }
2426 else DEBUG(D_receive)
2427 debug_printf("TCP_INFO getsockopt: %s\n", strerror(errno));
2428
2429 # elif defined(TCP_INFO)
2430 struct tcp_info tinfo;
2431 socklen_t len = sizeof(tinfo);
2432
2433 if (getsockopt(fileno(smtp_out), IPPROTO_TCP, TCP_INFO, &tinfo, &len) == 0)
2434 # ifdef TCPI_OPT_SYN_DATA /* FreeBSD 11,12 do not seem to have this yet */
2435 if (tinfo.tcpi_options & TCPI_OPT_SYN_DATA)
2436 {
2437 DEBUG(D_receive)
2438 debug_printf("TFO mode connection (ACKd data-on-SYN)\n");
2439 f.tcp_in_fastopen_data = f.tcp_in_fastopen = TRUE;
2440 }
2441 else
2442 # endif
2443 if (tinfo.tcpi_state == TCP_SYN_RECV) /* Not seen on FreeBSD 12.1 */
2444 {
2445 DEBUG(D_receive)
2446 debug_printf("TFO mode connection (state TCP_SYN_RECV)\n");
2447 f.tcp_in_fastopen = TRUE;
2448 }
2449 else DEBUG(D_receive)
2450 debug_printf("TCP_INFO getsockopt: %s\n", strerror(errno));
2451 # endif
2452 }
2453 #endif
2454
2455
2456 /*************************************************
2457 * Start an SMTP session *
2458 *************************************************/
2459
2460 /* This function is called at the start of an SMTP session. Thereafter,
2461 smtp_setup_msg() is called to initiate each separate message. This
2462 function does host-specific testing, and outputs the banner line.
2463
2464 Arguments: none
2465 Returns: FALSE if the session can not continue; something has
2466 gone wrong, or the connection to the host is blocked
2467 */
2468
2469 BOOL
2470 smtp_start_session(void)
2471 {
2472 int esclen;
2473 uschar *user_msg, *log_msg;
2474 uschar *code, *esc;
2475 uschar *p, *s;
2476 gstring * ss;
2477
2478 gettimeofday(&smtp_connection_start, NULL);
2479 for (smtp_ch_index = 0; smtp_ch_index < SMTP_HBUFF_SIZE; smtp_ch_index++)
2480 smtp_connection_had[smtp_ch_index] = SCH_NONE;
2481 smtp_ch_index = 0;
2482
2483 /* Default values for certain variables */
2484
2485 fl.helo_seen = fl.esmtp = fl.helo_accept_junk = FALSE;
2486 smtp_mailcmd_count = 0;
2487 count_nonmail = TRUE_UNSET;
2488 synprot_error_count = unknown_command_count = nonmail_command_count = 0;
2489 smtp_delay_mail = smtp_rlm_base;
2490 fl.auth_advertised = FALSE;
2491 f.smtp_in_pipelining_advertised = f.smtp_in_pipelining_used = FALSE;
2492 f.pipelining_enable = TRUE;
2493 sync_cmd_limit = NON_SYNC_CMD_NON_PIPELINING;
2494 fl.smtp_exit_function_called = FALSE; /* For avoiding loop in not-quit exit */
2495
2496 /* If receiving by -bs from a trusted user, or testing with -bh, we allow
2497 authentication settings from -oMaa to remain in force. */
2498
2499 if (!host_checking && !f.sender_host_notsocket)
2500 sender_host_auth_pubname = sender_host_authenticated = NULL;
2501 authenticated_by = NULL;
2502
2503 #ifndef DISABLE_TLS
2504 tls_in.ver = tls_in.cipher = tls_in.peerdn = NULL;
2505 tls_in.ourcert = tls_in.peercert = NULL;
2506 tls_in.sni = NULL;
2507 tls_in.ocsp = OCSP_NOT_REQ;
2508 fl.tls_advertised = FALSE;
2509 #endif
2510 fl.dsn_advertised = FALSE;
2511 #ifdef SUPPORT_I18N
2512 fl.smtputf8_advertised = FALSE;
2513 #endif
2514
2515 /* Reset ACL connection variables */
2516
2517 acl_var_c = NULL;
2518
2519 /* Allow for trailing 0 in the command and data buffers. Tainted. */
2520
2521 smtp_cmd_buffer = store_get_perm(2*SMTP_CMD_BUFFER_SIZE + 2, TRUE);
2522
2523 smtp_cmd_buffer[0] = 0;
2524 smtp_data_buffer = smtp_cmd_buffer + SMTP_CMD_BUFFER_SIZE + 1;
2525
2526 /* For batched input, the protocol setting can be overridden from the
2527 command line by a trusted caller. */
2528
2529 if (smtp_batched_input)
2530 {
2531 if (!received_protocol) received_protocol = US"local-bsmtp";
2532 }
2533
2534 /* For non-batched SMTP input, the protocol setting is forced here. It will be
2535 reset later if any of EHLO/AUTH/STARTTLS are received. */
2536
2537 else
2538 received_protocol =
2539 (sender_host_address ? protocols : protocols_local) [pnormal];
2540
2541 /* Set up the buffer for inputting using direct read() calls, and arrange to
2542 call the local functions instead of the standard C ones. Place a NUL at the
2543 end of the buffer to safety-stop C-string reads from it. */
2544
2545 if (!(smtp_inbuffer = US malloc(IN_BUFFER_SIZE)))
2546 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "malloc() failed for SMTP input buffer");
2547 smtp_inbuffer[IN_BUFFER_SIZE-1] = '\0';
2548
2549 receive_getc = smtp_getc;
2550 receive_getbuf = smtp_getbuf;
2551 receive_get_cache = smtp_get_cache;
2552 receive_ungetc = smtp_ungetc;
2553 receive_feof = smtp_feof;
2554 receive_ferror = smtp_ferror;
2555 receive_smtp_buffered = smtp_buffered;
2556 smtp_inptr = smtp_inend = smtp_inbuffer;
2557 smtp_had_eof = smtp_had_error = 0;
2558
2559 /* Set up the message size limit; this may be host-specific */
2560
2561 thismessage_size_limit = expand_string_integer(message_size_limit, TRUE);
2562 if (expand_string_message)
2563 {
2564 if (thismessage_size_limit == -1)
2565 log_write(0, LOG_MAIN|LOG_PANIC, "unable to expand message_size_limit: "
2566 "%s", expand_string_message);
2567 else
2568 log_write(0, LOG_MAIN|LOG_PANIC, "invalid message_size_limit: "
2569 "%s", expand_string_message);
2570 smtp_closedown(US"Temporary local problem - please try later");
2571 return FALSE;
2572 }
2573
2574 /* When a message is input locally via the -bs or -bS options, sender_host_
2575 unknown is set unless -oMa was used to force an IP address, in which case it
2576 is checked like a real remote connection. When -bs is used from inetd, this
2577 flag is not set, causing the sending host to be checked. The code that deals
2578 with IP source routing (if configured) is never required for -bs or -bS and
2579 the flag sender_host_notsocket is used to suppress it.
2580
2581 If smtp_accept_max and smtp_accept_reserve are set, keep some connections in
2582 reserve for certain hosts and/or networks. */
2583
2584 if (!f.sender_host_unknown)
2585 {
2586 int rc;
2587 BOOL reserved_host = FALSE;
2588
2589 /* Look up IP options (source routing info) on the socket if this is not an
2590 -oMa "host", and if any are found, log them and drop the connection.
2591
2592 Linux (and others now, see below) is different to everyone else, so there
2593 has to be some conditional compilation here. Versions of Linux before 2.1.15
2594 used a structure whose name was "options". Somebody finally realized that
2595 this name was silly, and it got changed to "ip_options". I use the
2596 newer name here, but there is a fudge in the script that sets up os.h
2597 to define a macro in older Linux systems.
2598
2599 Sigh. Linux is a fast-moving target. Another generation of Linux uses
2600 glibc 2, which has chosen ip_opts for the structure name. This is now
2601 really a glibc thing rather than a Linux thing, so the condition name
2602 has been changed to reflect this. It is relevant also to GNU/Hurd.
2603
2604 Mac OS 10.x (Darwin) is like the later glibc versions, but without the
2605 setting of the __GLIBC__ macro, so we can't detect it automatically. There's
2606 a special macro defined in the os.h file.
2607
2608 Some DGUX versions on older hardware appear not to support IP options at
2609 all, so there is now a general macro which can be set to cut out this
2610 support altogether.
2611
2612 How to do this properly in IPv6 is not yet known. */
2613
2614 #if !HAVE_IPV6 && !defined(NO_IP_OPTIONS)
2615
2616 #ifdef GLIBC_IP_OPTIONS
2617 #if (!defined __GLIBC__) || (__GLIBC__ < 2)
2618 #define OPTSTYLE 1
2619 #else
2620 #define OPTSTYLE 2
2621 #endif
2622 #elif defined DARWIN_IP_OPTIONS
2623 #define OPTSTYLE 2
2624 #else
2625 #define OPTSTYLE 3
2626 #endif
2627
2628 if (!host_checking && !f.sender_host_notsocket)
2629 {
2630 #if OPTSTYLE == 1
2631 EXIM_SOCKLEN_T optlen = sizeof(struct ip_options) + MAX_IPOPTLEN;
2632 struct ip_options *ipopt = store_get(optlen, FALSE);
2633 #elif OPTSTYLE == 2
2634 struct ip_opts ipoptblock;
2635 struct ip_opts *ipopt = &ipoptblock;
2636 EXIM_SOCKLEN_T optlen = sizeof(ipoptblock);
2637 #else
2638 struct ipoption ipoptblock;
2639 struct ipoption *ipopt = &ipoptblock;
2640 EXIM_SOCKLEN_T optlen = sizeof(ipoptblock);
2641 #endif
2642
2643 /* Occasional genuine failures of getsockopt() have been seen - for
2644 example, "reset by peer". Therefore, just log and give up on this
2645 call, unless the error is ENOPROTOOPT. This error is given by systems
2646 that have the interfaces but not the mechanism - e.g. GNU/Hurd at the time
2647 of writing. So for that error, carry on - we just can't do an IP options
2648 check. */
2649
2650 DEBUG(D_receive) debug_printf("checking for IP options\n");
2651
2652 if (getsockopt(fileno(smtp_out), IPPROTO_IP, IP_OPTIONS, US (ipopt),
2653 &optlen) < 0)
2654 {
2655 if (errno != ENOPROTOOPT)
2656 {
2657 log_write(0, LOG_MAIN, "getsockopt() failed from %s: %s",
2658 host_and_ident(FALSE), strerror(errno));
2659 smtp_printf("451 SMTP service not available\r\n", FALSE);
2660 return FALSE;
2661 }
2662 }
2663
2664 /* Deal with any IP options that are set. On the systems I have looked at,
2665 the value of MAX_IPOPTLEN has been 40, meaning that there should never be
2666 more logging data than will fit in big_buffer. Nevertheless, after somebody
2667 questioned this code, I've added in some paranoid checking. */
2668
2669 else if (optlen > 0)
2670 {
2671 uschar *p = big_buffer;
2672 uschar *pend = big_buffer + big_buffer_size;
2673 uschar *adptr;
2674 int optcount;
2675 struct in_addr addr;
2676
2677 #if OPTSTYLE == 1
2678 uschar *optstart = US (ipopt->__data);
2679 #elif OPTSTYLE == 2
2680 uschar *optstart = US (ipopt->ip_opts);
2681 #else
2682 uschar *optstart = US (ipopt->ipopt_list);
2683 #endif
2684
2685 DEBUG(D_receive) debug_printf("IP options exist\n");
2686
2687 Ustrcpy(p, "IP options on incoming call:");
2688 p += Ustrlen(p);
2689
2690 for (uschar * opt = optstart; opt && opt < US (ipopt) + optlen; )
2691 switch (*opt)
2692 {
2693 case IPOPT_EOL:
2694 opt = NULL;
2695 break;
2696
2697 case IPOPT_NOP:
2698 opt++;
2699 break;
2700
2701 case IPOPT_SSRR:
2702 case IPOPT_LSRR:
2703 if (!string_format(p, pend-p, " %s [@%s",
2704 (*opt == IPOPT_SSRR)? "SSRR" : "LSRR",
2705 #if OPTSTYLE == 1
2706 inet_ntoa(*((struct in_addr *)(&(ipopt->faddr))))))
2707 #elif OPTSTYLE == 2
2708 inet_ntoa(ipopt->ip_dst)))
2709 #else
2710 inet_ntoa(ipopt->ipopt_dst)))
2711 #endif
2712 {
2713 opt = NULL;
2714 break;
2715 }
2716
2717 p += Ustrlen(p);
2718 optcount = (opt[1] - 3) / sizeof(struct in_addr);
2719 adptr = opt + 3;
2720 while (optcount-- > 0)
2721 {
2722 memcpy(&addr, adptr, sizeof(addr));
2723 if (!string_format(p, pend - p - 1, "%s%s",
2724 (optcount == 0)? ":" : "@", inet_ntoa(addr)))
2725 {
2726 opt = NULL;
2727 break;
2728 }
2729 p += Ustrlen(p);
2730 adptr += sizeof(struct in_addr);
2731 }
2732 *p++ = ']';
2733 opt += opt[1];
2734 break;
2735
2736 default:
2737 {
2738 if (pend - p < 4 + 3*opt[1]) { opt = NULL; break; }
2739 Ustrcat(p, "[ ");
2740 p += 2;
2741 for (int i = 0; i < opt[1]; i++)
2742 p += sprintf(CS p, "%2.2x ", opt[i]);
2743 *p++ = ']';
2744 }
2745 opt += opt[1];
2746 break;
2747 }
2748
2749 *p = 0;
2750 log_write(0, LOG_MAIN, "%s", big_buffer);
2751
2752 /* Refuse any call with IP options. This is what tcpwrappers 7.5 does. */
2753
2754 log_write(0, LOG_MAIN|LOG_REJECT,
2755 "connection from %s refused (IP options)", host_and_ident(FALSE));
2756
2757 smtp_printf("554 SMTP service not available\r\n", FALSE);
2758 return FALSE;
2759 }
2760
2761 /* Length of options = 0 => there are no options */
2762
2763 else DEBUG(D_receive) debug_printf("no IP options found\n");
2764 }
2765 #endif /* HAVE_IPV6 && !defined(NO_IP_OPTIONS) */
2766
2767 /* Set keep-alive in socket options. The option is on by default. This
2768 setting is an attempt to get rid of some hanging connections that stick in
2769 read() when the remote end (usually a dialup) goes away. */
2770
2771 if (smtp_accept_keepalive && !f.sender_host_notsocket)
2772 ip_keepalive(fileno(smtp_out), sender_host_address, FALSE);
2773
2774 /* If the current host matches host_lookup, set the name by doing a
2775 reverse lookup. On failure, sender_host_name will be NULL and
2776 host_lookup_failed will be TRUE. This may or may not be serious - optional
2777 checks later. */
2778
2779 if (verify_check_host(&host_lookup) == OK)
2780 {
2781 (void)host_name_lookup();
2782 host_build_sender_fullhost();
2783 }
2784
2785 /* Delay this until we have the full name, if it is looked up. */
2786
2787 set_process_info("handling incoming connection from %s",
2788 host_and_ident(FALSE));
2789
2790 /* Expand smtp_receive_timeout, if needed */
2791
2792 if (smtp_receive_timeout_s)
2793 {
2794 uschar * exp;
2795 if ( !(exp = expand_string(smtp_receive_timeout_s))
2796 || !(*exp)
2797 || (smtp_receive_timeout = readconf_readtime(exp, 0, FALSE)) < 0
2798 )
2799 log_write(0, LOG_MAIN|LOG_PANIC,
2800 "bad value for smtp_receive_timeout: '%s'", exp ? exp : US"");
2801 }
2802
2803 /* Test for explicit connection rejection */
2804
2805 if (verify_check_host(&host_reject_connection) == OK)
2806 {
2807 log_write(L_connection_reject, LOG_MAIN|LOG_REJECT, "refused connection "
2808 "from %s (host_reject_connection)", host_and_ident(FALSE));
2809 smtp_printf("554 SMTP service not available\r\n", FALSE);
2810 return FALSE;
2811 }
2812
2813 /* Test with TCP Wrappers if so configured. There is a problem in that
2814 hosts_ctl() returns 0 (deny) under a number of system failure circumstances,
2815 such as disks dying. In these cases, it is desirable to reject with a 4xx
2816 error instead of a 5xx error. There isn't a "right" way to detect such
2817 problems. The following kludge is used: errno is zeroed before calling
2818 hosts_ctl(). If the result is "reject", a 5xx error is given only if the
2819 value of errno is 0 or ENOENT (which happens if /etc/hosts.{allow,deny} does
2820 not exist). */
2821
2822 #ifdef USE_TCP_WRAPPERS
2823 errno = 0;
2824 if (!(tcp_wrappers_name = expand_string(tcp_wrappers_daemon_name)))
2825 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "Expansion of \"%s\" "
2826 "(tcp_wrappers_name) failed: %s", string_printing(tcp_wrappers_name),
2827 expand_string_message);
2828
2829 if (!hosts_ctl(tcp_wrappers_name,
2830 sender_host_name ? CS sender_host_name : STRING_UNKNOWN,
2831 sender_host_address ? CS sender_host_address : STRING_UNKNOWN,
2832 sender_ident ? CS sender_ident : STRING_UNKNOWN))
2833 {
2834 if (errno == 0 || errno == ENOENT)
2835 {
2836 HDEBUG(D_receive) debug_printf("tcp wrappers rejection\n");
2837 log_write(L_connection_reject,
2838 LOG_MAIN|LOG_REJECT, "refused connection from %s "
2839 "(tcp wrappers)", host_and_ident(FALSE));
2840 smtp_printf("554 SMTP service not available\r\n", FALSE);
2841 }
2842 else
2843 {
2844 int save_errno = errno;
2845 HDEBUG(D_receive) debug_printf("tcp wrappers rejected with unexpected "
2846 "errno value %d\n", save_errno);
2847 log_write(L_connection_reject,
2848 LOG_MAIN|LOG_REJECT, "temporarily refused connection from %s "
2849 "(tcp wrappers errno=%d)", host_and_ident(FALSE), save_errno);
2850 smtp_printf("451 Temporary local problem - please try later\r\n", FALSE);
2851 }
2852 return FALSE;
2853 }
2854 #endif
2855
2856 /* Check for reserved slots. The value of smtp_accept_count has already been
2857 incremented to include this process. */
2858
2859 if (smtp_accept_max > 0 &&
2860 smtp_accept_count > smtp_accept_max - smtp_accept_reserve)
2861 {
2862 if ((rc = verify_check_host(&smtp_reserve_hosts)) != OK)
2863 {
2864 log_write(L_connection_reject,
2865 LOG_MAIN, "temporarily refused connection from %s: not in "
2866 "reserve list: connected=%d max=%d reserve=%d%s",
2867 host_and_ident(FALSE), smtp_accept_count - 1, smtp_accept_max,
2868 smtp_accept_reserve, (rc == DEFER)? " (lookup deferred)" : "");
2869 smtp_printf("421 %s: Too many concurrent SMTP connections; "
2870 "please try again later\r\n", FALSE, smtp_active_hostname);
2871 return FALSE;
2872 }
2873 reserved_host = TRUE;
2874 }
2875
2876 /* If a load level above which only messages from reserved hosts are
2877 accepted is set, check the load. For incoming calls via the daemon, the
2878 check is done in the superior process if there are no reserved hosts, to
2879 save a fork. In all cases, the load average will already be available
2880 in a global variable at this point. */
2881
2882 if (smtp_load_reserve >= 0 &&
2883 load_average > smtp_load_reserve &&
2884 !reserved_host &&
2885 verify_check_host(&smtp_reserve_hosts) != OK)
2886 {
2887 log_write(L_connection_reject,
2888 LOG_MAIN, "temporarily refused connection from %s: not in "
2889 "reserve list and load average = %.2f", host_and_ident(FALSE),
2890 (double)load_average/1000.0);
2891 smtp_printf("421 %s: Too much load; please try again later\r\n", FALSE,
2892 smtp_active_hostname);
2893 return FALSE;
2894 }
2895
2896 /* Determine whether unqualified senders or recipients are permitted
2897 for this host. Unfortunately, we have to do this every time, in order to
2898 set the flags so that they can be inspected when considering qualifying
2899 addresses in the headers. For a site that permits no qualification, this
2900 won't take long, however. */
2901
2902 f.allow_unqualified_sender =
2903 verify_check_host(&sender_unqualified_hosts) == OK;
2904
2905 f.allow_unqualified_recipient =
2906 verify_check_host(&recipient_unqualified_hosts) == OK;
2907
2908 /* Determine whether HELO/EHLO is required for this host. The requirement
2909 can be hard or soft. */
2910
2911 fl.helo_required = verify_check_host(&helo_verify_hosts) == OK;
2912 if (!fl.helo_required)
2913 fl.helo_verify = verify_check_host(&helo_try_verify_hosts) == OK;
2914
2915 /* Determine whether this hosts is permitted to send syntactic junk
2916 after a HELO or EHLO command. */
2917
2918 fl.helo_accept_junk = verify_check_host(&helo_accept_junk_hosts) == OK;
2919 }
2920
2921 /* For batch SMTP input we are now done. */
2922
2923 if (smtp_batched_input) return TRUE;
2924
2925 /* If valid Proxy Protocol source is connecting, set up session.
2926 * Failure will not allow any SMTP function other than QUIT. */
2927
2928 #ifdef SUPPORT_PROXY
2929 proxy_session = FALSE;
2930 f.proxy_session_failed = FALSE;
2931 if (check_proxy_protocol_host())
2932 setup_proxy_protocol_host();
2933 #endif
2934
2935 /* Start up TLS if tls_on_connect is set. This is for supporting the legacy
2936 smtps port for use with older style SSL MTAs. */
2937
2938 #ifndef DISABLE_TLS
2939 if (tls_in.on_connect)
2940 {
2941 if (tls_server_start(tls_require_ciphers, &user_msg) != OK)
2942 return smtp_log_tls_fail(user_msg);
2943 cmd_list[CMD_LIST_TLS_AUTH].is_mail_cmd = TRUE;
2944 }
2945 #endif
2946
2947 /* Run the connect ACL if it exists */
2948
2949 user_msg = NULL;
2950 if (acl_smtp_connect)
2951 {
2952 int rc;
2953 if ((rc = acl_check(ACL_WHERE_CONNECT, NULL, acl_smtp_connect, &user_msg,
2954 &log_msg)) != OK)
2955 {
2956 (void) smtp_handle_acl_fail(ACL_WHERE_CONNECT, rc, user_msg, log_msg);
2957 return FALSE;
2958 }
2959 }
2960
2961 /* Output the initial message for a two-way SMTP connection. It may contain
2962 newlines, which then cause a multi-line response to be given. */
2963
2964 code = US"220"; /* Default status code */
2965 esc = US""; /* Default extended status code */
2966 esclen = 0; /* Length of esc */
2967
2968 if (!user_msg)
2969 {
2970 if (!(s = expand_string(smtp_banner)))
2971 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "Expansion of \"%s\" (smtp_banner) "
2972 "failed: %s", smtp_banner, expand_string_message);
2973 }
2974 else
2975 {
2976 int codelen = 3;
2977 s = user_msg;
2978 smtp_message_code(&code, &codelen, &s, NULL, TRUE);
2979 if (codelen > 4)
2980 {
2981 esc = code + 4;
2982 esclen = codelen - 4;
2983 }
2984 }
2985
2986 /* Remove any terminating newlines; might as well remove trailing space too */
2987
2988 p = s + Ustrlen(s);
2989 while (p > s && isspace(p[-1])) p--;
2990 *p = 0;
2991
2992 /* It seems that CC:Mail is braindead, and assumes that the greeting message
2993 is all contained in a single IP packet. The original code wrote out the
2994 greeting using several calls to fprint/fputc, and on busy servers this could
2995 cause it to be split over more than one packet - which caused CC:Mail to fall
2996 over when it got the second part of the greeting after sending its first
2997 command. Sigh. To try to avoid this, build the complete greeting message
2998 first, and output it in one fell swoop. This gives a better chance of it
2999 ending up as a single packet. */
3000
3001 ss = string_get(256);
3002
3003 p = s;
3004 do /* At least once, in case we have an empty string */
3005 {
3006 int len;
3007 uschar *linebreak = Ustrchr(p, '\n');
3008 ss = string_catn(ss, code, 3);
3009 if (!linebreak)
3010 {
3011 len = Ustrlen(p);
3012 ss = string_catn(ss, US" ", 1);
3013 }
3014 else
3015 {
3016 len = linebreak - p;
3017 ss = string_catn(ss, US"-", 1);
3018 }
3019 ss = string_catn(ss, esc, esclen);
3020 ss = string_catn(ss, p, len);
3021 ss = string_catn(ss, US"\r\n", 2);
3022 p += len;
3023 if (linebreak) p++;
3024 }
3025 while (*p);
3026
3027 /* Before we write the banner, check that there is no input pending, unless
3028 this synchronisation check is disabled. */
3029
3030 #ifndef DISABLE_PIPE_CONNECT
3031 fl.pipe_connect_acceptable =
3032 sender_host_address && verify_check_host(&pipe_connect_advertise_hosts) == OK;
3033
3034 if (!check_sync())
3035 if (fl.pipe_connect_acceptable)
3036 f.smtp_in_early_pipe_used = TRUE;
3037 else
3038 #else
3039 if (!check_sync())
3040 #endif
3041 {
3042 unsigned n = smtp_inend - smtp_inptr;
3043 if (n > 128) n = 128;
3044
3045 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP protocol "
3046 "synchronization error (input sent without waiting for greeting): "
3047 "rejected connection from %s input=\"%s\"", host_and_ident(TRUE),
3048 string_printing(string_copyn(smtp_inptr, n)));
3049 smtp_printf("554 SMTP synchronization error\r\n", FALSE);
3050 return FALSE;
3051 }
3052
3053 /* Now output the banner */
3054 /*XXX the ehlo-resp code does its own tls/nontls bit. Maybe subroutine that? */
3055
3056 smtp_printf("%s",
3057 #ifndef DISABLE_PIPE_CONNECT
3058 fl.pipe_connect_acceptable && pipeline_connect_sends(),
3059 #else
3060 FALSE,
3061 #endif
3062 string_from_gstring(ss));
3063
3064 /* Attempt to see if we sent the banner before the last ACK of the 3-way
3065 handshake arrived. If so we must have managed a TFO. */
3066
3067 #ifdef TCP_FASTOPEN
3068 if (sender_host_address && !f.sender_host_notsocket) tfo_in_check();
3069 #endif
3070
3071 return TRUE;
3072 }
3073
3074
3075
3076
3077
3078 /*************************************************
3079 * Handle SMTP syntax and protocol errors *
3080 *************************************************/
3081
3082 /* Write to the log for SMTP syntax errors in incoming commands, if configured
3083 to do so. Then transmit the error response. The return value depends on the
3084 number of syntax and protocol errors in this SMTP session.
3085
3086 Arguments:
3087 type error type, given as a log flag bit
3088 code response code; <= 0 means don't send a response
3089 data data to reflect in the response (can be NULL)
3090 errmess the error message
3091
3092 Returns: -1 limit of syntax/protocol errors NOT exceeded
3093 +1 limit of syntax/protocol errors IS exceeded
3094
3095 These values fit in with the values of the "done" variable in the main
3096 processing loop in smtp_setup_msg(). */
3097
3098 static int
3099 synprot_error(int type, int code, uschar *data, uschar *errmess)
3100 {
3101 int yield = -1;
3102
3103 log_write(type, LOG_MAIN, "SMTP %s error in \"%s\" %s %s",
3104 (type == L_smtp_syntax_error)? "syntax" : "protocol",
3105 string_printing(smtp_cmd_buffer), host_and_ident(TRUE), errmess);
3106
3107 if (++synprot_error_count > smtp_max_synprot_errors)
3108 {
3109 yield = 1;
3110 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
3111 "syntax or protocol errors (last command was \"%s\")",
3112 host_and_ident(FALSE), string_printing(smtp_cmd_buffer));
3113 }
3114
3115 if (code > 0)
3116 {
3117 smtp_printf("%d%c%s%s%s\r\n", FALSE, code, yield == 1 ? '-' : ' ',
3118 data ? data : US"", data ? US": " : US"", errmess);
3119 if (yield == 1)
3120 smtp_printf("%d Too many syntax or protocol errors\r\n", FALSE, code);
3121 }
3122
3123 return yield;
3124 }
3125
3126
3127
3128
3129 /*************************************************
3130 * Send SMTP response, possibly multiline *
3131 *************************************************/
3132
3133 /* There are, it seems, broken clients out there that cannot handle multiline
3134 responses. If no_multiline_responses is TRUE (it can be set from an ACL), we
3135 output nothing for non-final calls, and only the first line for anything else.
3136
3137 Arguments:
3138 code SMTP code, may involve extended status codes
3139 codelen length of smtp code; if > 4 there's an ESC
3140 final FALSE if the last line isn't the final line
3141 msg message text, possibly containing newlines
3142
3143 Returns: nothing
3144 */
3145
3146 void
3147 smtp_respond(uschar* code, int codelen, BOOL final, uschar *msg)
3148 {
3149 int esclen = 0;
3150 uschar *esc = US"";
3151
3152 if (!final && f.no_multiline_responses) return;
3153
3154 if (codelen > 4)
3155 {
3156 esc = code + 4;
3157 esclen = codelen - 4;
3158 }
3159
3160 /* If this is the first output for a (non-batch) RCPT command, see if all RCPTs
3161 have had the same. Note: this code is also present in smtp_printf(). It would
3162 be tidier to have it only in one place, but when it was added, it was easier to
3163 do it that way, so as not to have to mess with the code for the RCPT command,
3164 which sometimes uses smtp_printf() and sometimes smtp_respond(). */
3165
3166 if (fl.rcpt_in_progress)
3167 {
3168 if (rcpt_smtp_response == NULL)
3169 rcpt_smtp_response = string_copy(msg);
3170 else if (fl.rcpt_smtp_response_same &&
3171 Ustrcmp(rcpt_smtp_response, msg) != 0)
3172 fl.rcpt_smtp_response_same = FALSE;
3173 fl.rcpt_in_progress = FALSE;
3174 }
3175
3176 /* Now output the message, splitting it up into multiple lines if necessary.
3177 We only handle pipelining these responses as far as nonfinal/final groups,
3178 not the whole MAIL/RCPT/DATA response set. */
3179
3180 for (;;)
3181 {
3182 uschar *nl = Ustrchr(msg, '\n');
3183 if (nl == NULL)
3184 {
3185 smtp_printf("%.3s%c%.*s%s\r\n", !final, code, final ? ' ':'-', esclen, esc, msg);
3186 return;
3187 }
3188 else if (nl[1] == 0 || f.no_multiline_responses)
3189 {
3190 smtp_printf("%.3s%c%.*s%.*s\r\n", !final, code, final ? ' ':'-', esclen, esc,
3191 (int)(nl - msg), msg);
3192 return;
3193 }
3194 else
3195 {
3196 smtp_printf("%.3s-%.*s%.*s\r\n", TRUE, code, esclen, esc, (int)(nl - msg), msg);
3197 msg = nl + 1;
3198 Uskip_whitespace(&msg);
3199 }
3200 }
3201 }
3202
3203
3204
3205
3206 /*************************************************
3207 * Parse user SMTP message *
3208 *************************************************/
3209
3210 /* This function allows for user messages overriding the response code details
3211 by providing a suitable response code string at the start of the message
3212 user_msg. Check the message for starting with a response code and optionally an
3213 extended status code. If found, check that the first digit is valid, and if so,
3214 change the code pointer and length to use the replacement. An invalid code
3215 causes a panic log; in this case, if the log messages is the same as the user
3216 message, we must also adjust the value of the log message to show the code that
3217 is actually going to be used (the original one).
3218
3219 This function is global because it is called from receive.c as well as within
3220 this module.
3221
3222 Note that the code length returned includes the terminating whitespace
3223 character, which is always included in the regex match.
3224
3225 Arguments:
3226 code SMTP code, may involve extended status codes
3227 codelen length of smtp code; if > 4 there's an ESC
3228 msg message text
3229 log_msg optional log message, to be adjusted with the new SMTP code
3230 check_valid if true, verify the response code
3231
3232 Returns: nothing
3233 */
3234
3235 void
3236 smtp_message_code(uschar **code, int *codelen, uschar **msg, uschar **log_msg,
3237 BOOL check_valid)
3238 {
3239 int n;
3240 int ovector[3];
3241
3242 if (!msg || !*msg) return;
3243
3244 if ((n = pcre_exec(regex_smtp_code, NULL, CS *msg, Ustrlen(*msg), 0,
3245 PCRE_EOPT, ovector, sizeof(ovector)/sizeof(int))) < 0) return;
3246
3247 if (check_valid && (*msg)[0] != (*code)[0])
3248 {
3249 log_write(0, LOG_MAIN|LOG_PANIC, "configured error code starts with "
3250 "incorrect digit (expected %c) in \"%s\"", (*code)[0], *msg);
3251 if (log_msg != NULL && *log_msg == *msg)
3252 *log_msg = string_sprintf("%s %s", *code, *log_msg + ovector[1]);
3253 }
3254 else
3255 {
3256 *code = *msg;
3257 *codelen = ovector[1]; /* Includes final space */
3258 }
3259 *msg += ovector[1]; /* Chop the code off the message */
3260 return;
3261 }
3262
3263
3264
3265
3266 /*************************************************
3267 * Handle an ACL failure *
3268 *************************************************/
3269
3270 /* This function is called when acl_check() fails. As well as calls from within
3271 this module, it is called from receive.c for an ACL after DATA. It sorts out
3272 logging the incident, and sends the error response. A message containing
3273 newlines is turned into a multiline SMTP response, but for logging, only the
3274 first line is used.
3275
3276 There's a table of default permanent failure response codes to use in
3277 globals.c, along with the table of names. VFRY is special. Despite RFC1123 it
3278 defaults disabled in Exim. However, discussion in connection with RFC 821bis
3279 (aka RFC 2821) has concluded that the response should be 252 in the disabled
3280 state, because there are broken clients that try VRFY before RCPT. A 5xx
3281 response should be given only when the address is positively known to be
3282 undeliverable. Sigh. We return 252 if there is no VRFY ACL or it provides
3283 no explicit code, but if there is one we let it know best.
3284 Also, for ETRN, 458 is given on refusal, and for AUTH, 503.
3285
3286 From Exim 4.63, it is possible to override the response code details by
3287 providing a suitable response code string at the start of the message provided
3288 in user_msg. The code's first digit is checked for validity.
3289
3290 Arguments:
3291 where where the ACL was called from
3292 rc the failure code
3293 user_msg a message that can be included in an SMTP response
3294 log_msg a message for logging
3295
3296 Returns: 0 in most cases
3297 2 if the failure code was FAIL_DROP, in which case the
3298 SMTP connection should be dropped (this value fits with the
3299 "done" variable in smtp_setup_msg() below)
3300 */
3301
3302 int
3303 smtp_handle_acl_fail(int where, int rc, uschar *user_msg, uschar *log_msg)
3304 {
3305 BOOL drop = rc == FAIL_DROP;
3306 int codelen = 3;
3307 uschar *smtp_code;
3308 uschar *lognl;
3309 uschar *sender_info = US"";
3310 uschar *what =
3311 #ifdef WITH_CONTENT_SCAN
3312 where == ACL_WHERE_MIME ? US"during MIME ACL checks" :
3313 #endif
3314 where == ACL_WHERE_PREDATA ? US"DATA" :
3315 where == ACL_WHERE_DATA ? US"after DATA" :
3316 #ifndef DISABLE_PRDR
3317 where == ACL_WHERE_PRDR ? US"after DATA PRDR" :
3318 #endif
3319 smtp_cmd_data ?
3320 string_sprintf("%s %s", acl_wherenames[where], smtp_cmd_data) :
3321 string_sprintf("%s in \"connect\" ACL", acl_wherenames[where]);
3322
3323 if (drop) rc = FAIL;
3324
3325 /* Set the default SMTP code, and allow a user message to change it. */
3326
3327 smtp_code = rc == FAIL ? acl_wherecodes[where] : US"451";
3328 smtp_message_code(&smtp_code, &codelen, &user_msg, &log_msg,
3329 where != ACL_WHERE_VRFY);
3330
3331 /* We used to have sender_address here; however, there was a bug that was not
3332 updating sender_address after a rewrite during a verify. When this bug was
3333 fixed, sender_address at this point became the rewritten address. I'm not sure
3334 this is what should be logged, so I've changed to logging the unrewritten
3335 address to retain backward compatibility. */
3336
3337 #ifndef WITH_CONTENT_SCAN
3338 if (where == ACL_WHERE_RCPT || where == ACL_WHERE_DATA)
3339 #else
3340 if (where == ACL_WHERE_RCPT || where == ACL_WHERE_DATA || where == ACL_WHERE_MIME)
3341 #endif
3342 {
3343 sender_info = string_sprintf("F=<%s>%s%s%s%s ",
3344 sender_address_unrewritten ? sender_address_unrewritten : sender_address,
3345 sender_host_authenticated ? US" A=" : US"",
3346 sender_host_authenticated ? sender_host_authenticated : US"",
3347 sender_host_authenticated && authenticated_id ? US":" : US"",
3348 sender_host_authenticated && authenticated_id ? authenticated_id : US""
3349 );
3350 }
3351
3352 /* If there's been a sender verification failure with a specific message, and
3353 we have not sent a response about it yet, do so now, as a preliminary line for
3354 failures, but not defers. However, always log it for defer, and log it for fail
3355 unless the sender_verify_fail log selector has been turned off. */
3356
3357 if (sender_verified_failed &&
3358 !testflag(sender_verified_failed, af_sverify_told))
3359 {
3360 BOOL save_rcpt_in_progress = fl.rcpt_in_progress;
3361 fl.rcpt_in_progress = FALSE; /* So as not to treat these as the error */
3362
3363 setflag(sender_verified_failed, af_sverify_told);
3364
3365 if (rc != FAIL || LOGGING(sender_verify_fail))
3366 log_write(0, LOG_MAIN|LOG_REJECT, "%s sender verify %s for <%s>%s",
3367 host_and_ident(TRUE),
3368 ((sender_verified_failed->special_action & 255) == DEFER)? "defer":"fail",
3369 sender_verified_failed->address,
3370 (sender_verified_failed->message == NULL)? US"" :
3371 string_sprintf(": %s", sender_verified_failed->message));
3372
3373 if (rc == FAIL && sender_verified_failed->user_message)
3374 smtp_respond(smtp_code, codelen, FALSE, string_sprintf(
3375 testflag(sender_verified_failed, af_verify_pmfail)?
3376 "Postmaster verification failed while checking <%s>\n%s\n"
3377 "Several RFCs state that you are required to have a postmaster\n"
3378 "mailbox for each mail domain. This host does not accept mail\n"
3379 "from domains whose servers reject the postmaster address."
3380 :
3381 testflag(sender_verified_failed, af_verify_nsfail)?
3382 "Callback setup failed while verifying <%s>\n%s\n"
3383 "The initial connection, or a HELO or MAIL FROM:<> command was\n"
3384 "rejected. Refusing MAIL FROM:<> does not help fight spam, disregards\n"
3385 "RFC requirements, and stops you from receiving standard bounce\n"
3386 "messages. This host does not accept mail from domains whose servers\n"
3387 "refuse bounces."
3388 :
3389 "Verification failed for <%s>\n%s",
3390 sender_verified_failed->address,
3391 sender_verified_failed->user_message));
3392
3393 fl.rcpt_in_progress = save_rcpt_in_progress;
3394 }
3395
3396 /* Sort out text for logging */
3397
3398 log_msg = log_msg ? string_sprintf(": %s", log_msg) : US"";
3399 if ((lognl = Ustrchr(log_msg, '\n'))) *lognl = 0;
3400
3401 /* Send permanent failure response to the command, but the code used isn't
3402 always a 5xx one - see comments at the start of this function. If the original
3403 rc was FAIL_DROP we drop the connection and yield 2. */
3404
3405 if (rc == FAIL)
3406 smtp_respond(smtp_code, codelen, TRUE,
3407 user_msg ? user_msg : US"Administrative prohibition");
3408
3409 /* Send temporary failure response to the command. Don't give any details,
3410 unless acl_temp_details is set. This is TRUE for a callout defer, a "defer"
3411 verb, and for a header verify when smtp_return_error_details is set.
3412
3413 This conditional logic is all somewhat of a mess because of the odd
3414 interactions between temp_details and return_error_details. One day it should
3415 be re-implemented in a tidier fashion. */
3416
3417 else
3418 if (f.acl_temp_details && user_msg)
3419 {
3420 if ( smtp_return_error_details
3421 && sender_verified_failed
3422 && sender_verified_failed->message
3423 )
3424 smtp_respond(smtp_code, codelen, FALSE, sender_verified_failed->message);
3425
3426 smtp_respond(smtp_code, codelen, TRUE, user_msg);
3427 }
3428 else
3429 smtp_respond(smtp_code, codelen, TRUE,
3430 US"Temporary local problem - please try later");
3431
3432 /* Log the incident to the logs that are specified by log_reject_target
3433 (default main, reject). This can be empty to suppress logging of rejections. If
3434 the connection is not forcibly to be dropped, return 0. Otherwise, log why it
3435 is closing if required and return 2. */
3436
3437 if (log_reject_target != 0)
3438 {
3439 #ifndef DISABLE_TLS
3440 gstring * g = s_tlslog(NULL);
3441 uschar * tls = string_from_gstring(g);
3442 if (!tls) tls = US"";
3443 #else
3444 uschar * tls = US"";
3445 #endif
3446 log_write(where == ACL_WHERE_CONNECT ? L_connection_reject : 0,
3447 log_reject_target, "%s%s%s %s%srejected %s%s",
3448 LOGGING(dnssec) && sender_host_dnssec ? US" DS" : US"",
3449 host_and_ident(TRUE),
3450 tls,
3451 sender_info,
3452 rc == FAIL ? US"" : US"temporarily ",
3453 what, log_msg);
3454 }
3455
3456 if (!drop) return 0;
3457
3458 log_write(L_smtp_connection, LOG_MAIN, "%s closed by DROP in ACL",
3459 smtp_get_connection_info());
3460
3461 /* Run the not-quit ACL, but without any custom messages. This should not be a
3462 problem, because we get here only if some other ACL has issued "drop", and
3463 in that case, *its* custom messages will have been used above. */
3464
3465 smtp_notquit_exit(US"acl-drop", NULL, NULL);
3466 return 2;
3467 }
3468
3469
3470
3471
3472 /*************************************************
3473 * Handle SMTP exit when QUIT is not given *
3474 *************************************************/
3475
3476 /* This function provides a logging/statistics hook for when an SMTP connection
3477 is dropped on the floor or the other end goes away. It's a global function
3478 because it's called from receive.c as well as this module. As well as running
3479 the NOTQUIT ACL, if there is one, this function also outputs a final SMTP
3480 response, either with a custom message from the ACL, or using a default. There
3481 is one case, however, when no message is output - after "drop". In that case,
3482 the ACL that obeyed "drop" has already supplied the custom message, and NULL is
3483 passed to this function.
3484
3485 In case things go wrong while processing this function, causing an error that
3486 may re-enter this function, there is a recursion check.
3487
3488 Arguments:
3489 reason What $smtp_notquit_reason will be set to in the ACL;
3490 if NULL, the ACL is not run
3491 code The error code to return as part of the response
3492 defaultrespond The default message if there's no user_msg
3493
3494 Returns: Nothing
3495 */
3496
3497 void
3498 smtp_notquit_exit(uschar *reason, uschar *code, uschar *defaultrespond, ...)
3499 {
3500 int rc;
3501 uschar *user_msg = NULL;
3502 uschar *log_msg = NULL;
3503
3504 /* Check for recursive call */
3505