7d629816034ff5154f2d704f1f5851298dc9a86c
[exim.git] / src / src / smtp_in.c
1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
4
5 /* Copyright (c) University of Cambridge 1995 - 2018 */
6 /* See the file NOTICE for conditions of use and distribution. */
7
8 /* Functions for handling an incoming SMTP call. */
9
10
11 #include "exim.h"
12 #include <assert.h>
13
14
15 /* Initialize for TCP wrappers if so configured. It appears that the macro
16 HAVE_IPV6 is used in some versions of the tcpd.h header, so we unset it before
17 including that header, and restore its value afterwards. */
18
19 #ifdef USE_TCP_WRAPPERS
20
21 #if HAVE_IPV6
22 #define EXIM_HAVE_IPV6
23 #endif
24 #undef HAVE_IPV6
25 #include <tcpd.h>
26 #undef HAVE_IPV6
27 #ifdef EXIM_HAVE_IPV6
28 #define HAVE_IPV6 TRUE
29 #endif
30
31 int allow_severity = LOG_INFO;
32 int deny_severity = LOG_NOTICE;
33 uschar *tcp_wrappers_name;
34 #endif
35
36
37 /* Size of buffer for reading SMTP commands. We used to use 512, as defined
38 by RFC 821. However, RFC 1869 specifies that this must be increased for SMTP
39 commands that accept arguments, and this in particular applies to AUTH, where
40 the data can be quite long. More recently this value was 2048 in Exim;
41 however, RFC 4954 (circa 2007) recommends 12288 bytes to handle AUTH. Clients
42 such as Thunderbird will send an AUTH with an initial-response for GSSAPI.
43 The maximum size of a Kerberos ticket under Windows 2003 is 12000 bytes, and
44 we need room to handle large base64-encoded AUTHs for GSSAPI.
45 */
46
47 #define SMTP_CMD_BUFFER_SIZE 16384
48
49 /* Size of buffer for reading SMTP incoming packets */
50
51 #define IN_BUFFER_SIZE 8192
52
53 /* Structure for SMTP command list */
54
55 typedef struct {
56 const char *name;
57 int len;
58 short int cmd;
59 short int has_arg;
60 short int is_mail_cmd;
61 } smtp_cmd_list;
62
63 /* Codes for identifying commands. We order them so that those that come first
64 are those for which synchronization is always required. Checking this can help
65 block some spam. */
66
67 enum {
68 /* These commands are required to be synchronized, i.e. to be the last in a
69 block of commands when pipelining. */
70
71 HELO_CMD, EHLO_CMD, DATA_CMD, /* These are listed in the pipelining */
72 VRFY_CMD, EXPN_CMD, NOOP_CMD, /* RFC as requiring synchronization */
73 ETRN_CMD, /* This by analogy with TURN from the RFC */
74 STARTTLS_CMD, /* Required by the STARTTLS RFC */
75 TLS_AUTH_CMD, /* auto-command at start of SSL */
76
77 /* This is a dummy to identify the non-sync commands when pipelining */
78
79 NON_SYNC_CMD_PIPELINING,
80
81 /* These commands need not be synchronized when pipelining */
82
83 MAIL_CMD, RCPT_CMD, RSET_CMD,
84
85 /* This is a dummy to identify the non-sync commands when not pipelining */
86
87 NON_SYNC_CMD_NON_PIPELINING,
88
89 /* RFC3030 section 2: "After all MAIL and RCPT responses are collected and
90 processed the message is sent using a series of BDAT commands"
91 implies that BDAT should be synchronized. However, we see Google, at least,
92 sending MAIL,RCPT,BDAT-LAST in a single packet, clearly not waiting for
93 processing of the RCPT response(s). We shall do the same, and not require
94 synch for BDAT. Worse, as the chunk may (very likely will) follow the
95 command-header in the same packet we cannot do the usual "is there any
96 follow-on data after the command line" even for non-pipeline mode.
97 So we'll need an explicit check after reading the expected chunk amount
98 when non-pipe, before sending the ACK. */
99
100 BDAT_CMD,
101
102 /* I have been unable to find a statement about the use of pipelining
103 with AUTH, so to be on the safe side it is here, though I kind of feel
104 it should be up there with the synchronized commands. */
105
106 AUTH_CMD,
107
108 /* I'm not sure about these, but I don't think they matter. */
109
110 QUIT_CMD, HELP_CMD,
111
112 #ifdef SUPPORT_PROXY
113 PROXY_FAIL_IGNORE_CMD,
114 #endif
115
116 /* These are specials that don't correspond to actual commands */
117
118 EOF_CMD, OTHER_CMD, BADARG_CMD, BADCHAR_CMD, BADSYN_CMD,
119 TOO_MANY_NONMAIL_CMD };
120
121
122 /* This is a convenience macro for adding the identity of an SMTP command
123 to the circular buffer that holds a list of the last n received. */
124
125 #define HAD(n) \
126 smtp_connection_had[smtp_ch_index++] = n; \
127 if (smtp_ch_index >= SMTP_HBUFF_SIZE) smtp_ch_index = 0
128
129
130 /*************************************************
131 * Local static variables *
132 *************************************************/
133
134 static auth_instance *authenticated_by;
135 static BOOL auth_advertised;
136 #ifdef SUPPORT_TLS
137 static BOOL tls_advertised;
138 #endif
139 static BOOL dsn_advertised;
140 static BOOL esmtp;
141 static BOOL helo_required = FALSE;
142 static BOOL helo_verify = FALSE;
143 static BOOL helo_seen;
144 static BOOL helo_accept_junk;
145 static BOOL count_nonmail;
146 static BOOL pipelining_advertised;
147 static BOOL rcpt_smtp_response_same;
148 static BOOL rcpt_in_progress;
149 static int nonmail_command_count;
150 static BOOL smtp_exit_function_called = 0;
151 #ifdef SUPPORT_I18N
152 static BOOL smtputf8_advertised;
153 #endif
154 static int synprot_error_count;
155 static int unknown_command_count;
156 static int sync_cmd_limit;
157 static int smtp_write_error = 0;
158
159 static uschar *rcpt_smtp_response;
160 static uschar *smtp_data_buffer;
161 static uschar *smtp_cmd_data;
162
163 /* We need to know the position of RSET, HELO, EHLO, AUTH, and STARTTLS. Their
164 final fields of all except AUTH are forced TRUE at the start of a new message
165 setup, to allow one of each between messages that is not counted as a nonmail
166 command. (In fact, only one of HELO/EHLO is not counted.) Also, we have to
167 allow a new EHLO after starting up TLS.
168
169 AUTH is "falsely" labelled as a mail command initially, so that it doesn't get
170 counted. However, the flag is changed when AUTH is received, so that multiple
171 failing AUTHs will eventually hit the limit. After a successful AUTH, another
172 AUTH is already forbidden. After a TLS session is started, AUTH's flag is again
173 forced TRUE, to allow for the re-authentication that can happen at that point.
174
175 QUIT is also "falsely" labelled as a mail command so that it doesn't up the
176 count of non-mail commands and possibly provoke an error.
177
178 tls_auth is a pseudo-command, never expected in input. It is activated
179 on TLS startup and looks for a tls authenticator. */
180
181 static smtp_cmd_list cmd_list[] = {
182 /* name len cmd has_arg is_mail_cmd */
183
184 { "rset", sizeof("rset")-1, RSET_CMD, FALSE, FALSE }, /* First */
185 { "helo", sizeof("helo")-1, HELO_CMD, TRUE, FALSE },
186 { "ehlo", sizeof("ehlo")-1, EHLO_CMD, TRUE, FALSE },
187 { "auth", sizeof("auth")-1, AUTH_CMD, TRUE, TRUE },
188 #ifdef SUPPORT_TLS
189 { "starttls", sizeof("starttls")-1, STARTTLS_CMD, FALSE, FALSE },
190 { "tls_auth", 0, TLS_AUTH_CMD, FALSE, FALSE },
191 #endif
192
193 /* If you change anything above here, also fix the definitions below. */
194
195 { "mail from:", sizeof("mail from:")-1, MAIL_CMD, TRUE, TRUE },
196 { "rcpt to:", sizeof("rcpt to:")-1, RCPT_CMD, TRUE, TRUE },
197 { "data", sizeof("data")-1, DATA_CMD, FALSE, TRUE },
198 { "bdat", sizeof("bdat")-1, BDAT_CMD, TRUE, TRUE },
199 { "quit", sizeof("quit")-1, QUIT_CMD, FALSE, TRUE },
200 { "noop", sizeof("noop")-1, NOOP_CMD, TRUE, FALSE },
201 { "etrn", sizeof("etrn")-1, ETRN_CMD, TRUE, FALSE },
202 { "vrfy", sizeof("vrfy")-1, VRFY_CMD, TRUE, FALSE },
203 { "expn", sizeof("expn")-1, EXPN_CMD, TRUE, FALSE },
204 { "help", sizeof("help")-1, HELP_CMD, TRUE, FALSE }
205 };
206
207 static smtp_cmd_list *cmd_list_end =
208 cmd_list + sizeof(cmd_list)/sizeof(smtp_cmd_list);
209
210 #define CMD_LIST_RSET 0
211 #define CMD_LIST_HELO 1
212 #define CMD_LIST_EHLO 2
213 #define CMD_LIST_AUTH 3
214 #define CMD_LIST_STARTTLS 4
215 #define CMD_LIST_TLS_AUTH 5
216
217 /* This list of names is used for performing the smtp_no_mail logging action.
218 It must be kept in step with the SCH_xxx enumerations. */
219
220 static uschar *smtp_names[] =
221 {
222 US"NONE", US"AUTH", US"DATA", US"BDAT", US"EHLO", US"ETRN", US"EXPN",
223 US"HELO", US"HELP", US"MAIL", US"NOOP", US"QUIT", US"RCPT", US"RSET",
224 US"STARTTLS", US"VRFY" };
225
226 static uschar *protocols_local[] = {
227 US"local-smtp", /* HELO */
228 US"local-smtps", /* The rare case EHLO->STARTTLS->HELO */
229 US"local-esmtp", /* EHLO */
230 US"local-esmtps", /* EHLO->STARTTLS->EHLO */
231 US"local-esmtpa", /* EHLO->AUTH */
232 US"local-esmtpsa" /* EHLO->STARTTLS->EHLO->AUTH */
233 };
234 static uschar *protocols[] = {
235 US"smtp", /* HELO */
236 US"smtps", /* The rare case EHLO->STARTTLS->HELO */
237 US"esmtp", /* EHLO */
238 US"esmtps", /* EHLO->STARTTLS->EHLO */
239 US"esmtpa", /* EHLO->AUTH */
240 US"esmtpsa" /* EHLO->STARTTLS->EHLO->AUTH */
241 };
242
243 #define pnormal 0
244 #define pextend 2
245 #define pcrpted 1 /* added to pextend or pnormal */
246 #define pauthed 2 /* added to pextend */
247
248 /* Sanity check and validate optional args to MAIL FROM: envelope */
249 enum {
250 ENV_MAIL_OPT_NULL,
251 ENV_MAIL_OPT_SIZE, ENV_MAIL_OPT_BODY, ENV_MAIL_OPT_AUTH,
252 #ifndef DISABLE_PRDR
253 ENV_MAIL_OPT_PRDR,
254 #endif
255 ENV_MAIL_OPT_RET, ENV_MAIL_OPT_ENVID,
256 #ifdef SUPPORT_I18N
257 ENV_MAIL_OPT_UTF8,
258 #endif
259 };
260 typedef struct {
261 uschar * name; /* option requested during MAIL cmd */
262 int value; /* enum type */
263 BOOL need_value; /* TRUE requires value (name=value pair format)
264 FALSE is a singleton */
265 } env_mail_type_t;
266 static env_mail_type_t env_mail_type_list[] = {
267 { US"SIZE", ENV_MAIL_OPT_SIZE, TRUE },
268 { US"BODY", ENV_MAIL_OPT_BODY, TRUE },
269 { US"AUTH", ENV_MAIL_OPT_AUTH, TRUE },
270 #ifndef DISABLE_PRDR
271 { US"PRDR", ENV_MAIL_OPT_PRDR, FALSE },
272 #endif
273 { US"RET", ENV_MAIL_OPT_RET, TRUE },
274 { US"ENVID", ENV_MAIL_OPT_ENVID, TRUE },
275 #ifdef SUPPORT_I18N
276 { US"SMTPUTF8",ENV_MAIL_OPT_UTF8, FALSE }, /* rfc6531 */
277 #endif
278 /* keep this the last entry */
279 { US"NULL", ENV_MAIL_OPT_NULL, FALSE },
280 };
281
282 /* When reading SMTP from a remote host, we have to use our own versions of the
283 C input-reading functions, in order to be able to flush the SMTP output only
284 when about to read more data from the socket. This is the only way to get
285 optimal performance when the client is using pipelining. Flushing for every
286 command causes a separate packet and reply packet each time; saving all the
287 responses up (when pipelining) combines them into one packet and one response.
288
289 For simplicity, these functions are used for *all* SMTP input, not only when
290 receiving over a socket. However, after setting up a secure socket (SSL), input
291 is read via the OpenSSL library, and another set of functions is used instead
292 (see tls.c).
293
294 These functions are set in the receive_getc etc. variables and called with the
295 same interface as the C functions. However, since there can only ever be
296 one incoming SMTP call, we just use a single buffer and flags. There is no need
297 to implement a complicated private FILE-like structure.*/
298
299 static uschar *smtp_inbuffer;
300 static uschar *smtp_inptr;
301 static uschar *smtp_inend;
302 static int smtp_had_eof;
303 static int smtp_had_error;
304
305
306 /* forward declarations */
307 static int smtp_read_command(BOOL check_sync, unsigned buffer_lim);
308 static int synprot_error(int type, int code, uschar *data, uschar *errmess);
309 static void smtp_quit_handler(uschar **, uschar **);
310 static void smtp_rset_handler(void);
311
312 /*************************************************
313 * Recheck synchronization *
314 *************************************************/
315
316 /* Synchronization checks can never be perfect because a packet may be on its
317 way but not arrived when the check is done. Normally, the checks happen when
318 commands are read: Exim ensures that there is no more input in the input buffer.
319 In normal cases, the response to the command will be fast, and there is no
320 further check.
321
322 However, for some commands an ACL is run, and that can include delays. In those
323 cases, it is useful to do another check on the input just before sending the
324 response. This also applies at the start of a connection. This function does
325 that check by means of the select() function, as long as the facility is not
326 disabled or inappropriate. A failure of select() is ignored.
327
328 When there is unwanted input, we read it so that it appears in the log of the
329 error.
330
331 Arguments: none
332 Returns: TRUE if all is well; FALSE if there is input pending
333 */
334
335 static BOOL
336 wouldblock_reading(void)
337 {
338 int fd, rc;
339 fd_set fds;
340 struct timeval tzero;
341
342 #ifdef SUPPORT_TLS
343 if (tls_in.active >= 0)
344 return !tls_could_read();
345 #endif
346
347 if (smtp_inptr < smtp_inend)
348 return FALSE;
349
350 fd = fileno(smtp_in);
351 FD_ZERO(&fds);
352 FD_SET(fd, &fds);
353 tzero.tv_sec = 0;
354 tzero.tv_usec = 0;
355 rc = select(fd + 1, (SELECT_ARG2_TYPE *)&fds, NULL, NULL, &tzero);
356
357 if (rc <= 0) return TRUE; /* Not ready to read */
358 rc = smtp_getc(GETC_BUFFER_UNLIMITED);
359 if (rc < 0) return TRUE; /* End of file or error */
360
361 smtp_ungetc(rc);
362 return FALSE;
363 }
364
365 static BOOL
366 check_sync(void)
367 {
368 if (!smtp_enforce_sync || !sender_host_address || sender_host_notsocket)
369 return TRUE;
370
371 return wouldblock_reading();
372 }
373
374
375 /* If there's input waiting (and we're doing pipelineing) then we can pipeline
376 a reponse with the one following. */
377
378 static BOOL
379 pipeline_response(void)
380 {
381 if ( !smtp_enforce_sync || !sender_host_address
382 || sender_host_notsocket || !pipelining_advertised)
383 return FALSE;
384
385 return !wouldblock_reading();
386 }
387
388
389
390 /*************************************************
391 * Log incomplete transactions *
392 *************************************************/
393
394 /* This function is called after a transaction has been aborted by RSET, QUIT,
395 connection drops or other errors. It logs the envelope information received
396 so far in order to preserve address verification attempts.
397
398 Argument: string to indicate what aborted the transaction
399 Returns: nothing
400 */
401
402 static void
403 incomplete_transaction_log(uschar *what)
404 {
405 if (sender_address == NULL || /* No transaction in progress */
406 !LOGGING(smtp_incomplete_transaction))
407 return;
408
409 /* Build list of recipients for logging */
410
411 if (recipients_count > 0)
412 {
413 int i;
414 raw_recipients = store_get(recipients_count * sizeof(uschar *));
415 for (i = 0; i < recipients_count; i++)
416 raw_recipients[i] = recipients_list[i].address;
417 raw_recipients_count = recipients_count;
418 }
419
420 log_write(L_smtp_incomplete_transaction, LOG_MAIN|LOG_SENDER|LOG_RECIPIENTS,
421 "%s incomplete transaction (%s)", host_and_ident(TRUE), what);
422 }
423
424
425
426
427 /* Refill the buffer, and notify DKIM verification code.
428 Return false for error or EOF.
429 */
430
431 static BOOL
432 smtp_refill(unsigned lim)
433 {
434 int rc, save_errno;
435 if (!smtp_out) return FALSE;
436 fflush(smtp_out);
437 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
438
439 /* Limit amount read, so non-message data is not fed to DKIM.
440 Take care to not touch the safety NUL at the end of the buffer. */
441
442 rc = read(fileno(smtp_in), smtp_inbuffer, MIN(IN_BUFFER_SIZE-1, lim));
443 save_errno = errno;
444 alarm(0);
445 if (rc <= 0)
446 {
447 /* Must put the error text in fixed store, because this might be during
448 header reading, where it releases unused store above the header. */
449 if (rc < 0)
450 {
451 smtp_had_error = save_errno;
452 smtp_read_error = string_copy_malloc(
453 string_sprintf(" (error: %s)", strerror(save_errno)));
454 }
455 else smtp_had_eof = 1;
456 return FALSE;
457 }
458 #ifndef DISABLE_DKIM
459 dkim_exim_verify_feed(smtp_inbuffer, rc);
460 #endif
461 smtp_inend = smtp_inbuffer + rc;
462 smtp_inptr = smtp_inbuffer;
463 return TRUE;
464 }
465
466 /*************************************************
467 * SMTP version of getc() *
468 *************************************************/
469
470 /* This gets the next byte from the SMTP input buffer. If the buffer is empty,
471 it flushes the output, and refills the buffer, with a timeout. The signal
472 handler is set appropriately by the calling function. This function is not used
473 after a connection has negotiated itself into an TLS/SSL state.
474
475 Arguments: lim Maximum amount to read/buffer
476 Returns: the next character or EOF
477 */
478
479 int
480 smtp_getc(unsigned lim)
481 {
482 if (smtp_inptr >= smtp_inend)
483 if (!smtp_refill(lim))
484 return EOF;
485 return *smtp_inptr++;
486 }
487
488 uschar *
489 smtp_getbuf(unsigned * len)
490 {
491 unsigned size;
492 uschar * buf;
493
494 if (smtp_inptr >= smtp_inend)
495 if (!smtp_refill(*len))
496 { *len = 0; return NULL; }
497
498 if ((size = smtp_inend - smtp_inptr) > *len) size = *len;
499 buf = smtp_inptr;
500 smtp_inptr += size;
501 *len = size;
502 return buf;
503 }
504
505 void
506 smtp_get_cache(void)
507 {
508 #ifndef DISABLE_DKIM
509 int n = smtp_inend - smtp_inptr;
510 if (n > 0)
511 dkim_exim_verify_feed(smtp_inptr, n);
512 #endif
513 }
514
515
516 /* Get a byte from the smtp input, in CHUNKING mode. Handle ack of the
517 previous BDAT chunk and getting new ones when we run out. Uses the
518 underlying smtp_getc or tls_getc both for that and for getting the
519 (buffered) data byte. EOD signals (an expected) no further data.
520 ERR signals a protocol error, and EOF a closed input stream.
521
522 Called from read_bdat_smtp() in receive.c for the message body, but also
523 by the headers read loop in receive_msg(); manipulates chunking_state
524 to handle the BDAT command/response.
525 Placed here due to the correlation with the above smtp_getc(), which it wraps,
526 and also by the need to do smtp command/response handling.
527
528 Arguments: lim (ignored)
529 Returns: the next character or ERR, EOD or EOF
530 */
531
532 int
533 bdat_getc(unsigned lim)
534 {
535 uschar * user_msg = NULL;
536 uschar * log_msg;
537
538 for(;;)
539 {
540 #ifndef DISABLE_DKIM
541 BOOL dkim_save;
542 #endif
543
544 if (chunking_data_left > 0)
545 return lwr_receive_getc(chunking_data_left--);
546
547 receive_getc = lwr_receive_getc;
548 receive_getbuf = lwr_receive_getbuf;
549 receive_ungetc = lwr_receive_ungetc;
550 #ifndef DISABLE_DKIM
551 dkim_save = dkim_collect_input;
552 dkim_collect_input = FALSE;
553 #endif
554
555 /* Unless PIPELINING was offered, there should be no next command
556 until after we ack that chunk */
557
558 if (!pipelining_advertised && !check_sync())
559 {
560 unsigned n = smtp_inend - smtp_inptr;
561 if (n > 32) n = 32;
562
563 incomplete_transaction_log(US"sync failure");
564 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP protocol synchronization error "
565 "(next input sent too soon: pipelining was not advertised): "
566 "rejected \"%s\" %s next input=\"%s\"%s",
567 smtp_cmd_buffer, host_and_ident(TRUE),
568 string_printing(string_copyn(smtp_inptr, n)),
569 smtp_inend - smtp_inptr > n ? "..." : "");
570 (void) synprot_error(L_smtp_protocol_error, 554, NULL,
571 US"SMTP synchronization error");
572 goto repeat_until_rset;
573 }
574
575 /* If not the last, ack the received chunk. The last response is delayed
576 until after the data ACL decides on it */
577
578 if (chunking_state == CHUNKING_LAST)
579 {
580 #ifndef DISABLE_DKIM
581 dkim_exim_verify_feed(NULL, 0); /* notify EOD */
582 #endif
583 return EOD;
584 }
585
586 smtp_printf("250 %u byte chunk received\r\n", FALSE, chunking_datasize);
587 chunking_state = CHUNKING_OFFERED;
588 DEBUG(D_receive) debug_printf("chunking state %d\n", (int)chunking_state);
589
590 /* Expect another BDAT cmd from input. RFC 3030 says nothing about
591 QUIT, RSET or NOOP but handling them seems obvious */
592
593 next_cmd:
594 switch(smtp_read_command(TRUE, 1))
595 {
596 default:
597 (void) synprot_error(L_smtp_protocol_error, 503, NULL,
598 US"only BDAT permissible after non-LAST BDAT");
599
600 repeat_until_rset:
601 switch(smtp_read_command(TRUE, 1))
602 {
603 case QUIT_CMD: smtp_quit_handler(&user_msg, &log_msg); /*FALLTHROUGH */
604 case EOF_CMD: return EOF;
605 case RSET_CMD: smtp_rset_handler(); return ERR;
606 default: if (synprot_error(L_smtp_protocol_error, 503, NULL,
607 US"only RSET accepted now") > 0)
608 return EOF;
609 goto repeat_until_rset;
610 }
611
612 case QUIT_CMD:
613 smtp_quit_handler(&user_msg, &log_msg);
614 /*FALLTHROUGH*/
615 case EOF_CMD:
616 return EOF;
617
618 case RSET_CMD:
619 smtp_rset_handler();
620 return ERR;
621
622 case NOOP_CMD:
623 HAD(SCH_NOOP);
624 smtp_printf("250 OK\r\n", FALSE);
625 goto next_cmd;
626
627 case BDAT_CMD:
628 {
629 int n;
630
631 if (sscanf(CS smtp_cmd_data, "%u %n", &chunking_datasize, &n) < 1)
632 {
633 (void) synprot_error(L_smtp_protocol_error, 501, NULL,
634 US"missing size for BDAT command");
635 return ERR;
636 }
637 chunking_state = strcmpic(smtp_cmd_data+n, US"LAST") == 0
638 ? CHUNKING_LAST : CHUNKING_ACTIVE;
639 chunking_data_left = chunking_datasize;
640 DEBUG(D_receive) debug_printf("chunking state %d, %d bytes\n",
641 (int)chunking_state, chunking_data_left);
642
643 if (chunking_datasize == 0)
644 if (chunking_state == CHUNKING_LAST)
645 return EOD;
646 else
647 {
648 (void) synprot_error(L_smtp_protocol_error, 504, NULL,
649 US"zero size for BDAT command");
650 goto repeat_until_rset;
651 }
652
653 receive_getc = bdat_getc;
654 receive_getbuf = bdat_getbuf; /* r~getbuf is never actually used */
655 receive_ungetc = bdat_ungetc;
656 #ifndef DISABLE_DKIM
657 dkim_collect_input = dkim_save;
658 #endif
659 break; /* to top of main loop */
660 }
661 }
662 }
663 }
664
665 uschar *
666 bdat_getbuf(unsigned * len)
667 {
668 uschar * buf;
669
670 if (chunking_data_left <= 0)
671 { *len = 0; return NULL; }
672
673 if (*len > chunking_data_left) *len = chunking_data_left;
674 buf = lwr_receive_getbuf(len); /* Either smtp_getbuf or tls_getbuf */
675 chunking_data_left -= *len;
676 return buf;
677 }
678
679 void
680 bdat_flush_data(void)
681 {
682 while (chunking_data_left)
683 {
684 unsigned n = chunking_data_left;
685 if (!bdat_getbuf(&n)) break;
686 }
687
688 receive_getc = lwr_receive_getc;
689 receive_getbuf = lwr_receive_getbuf;
690 receive_ungetc = lwr_receive_ungetc;
691
692 if (chunking_state != CHUNKING_LAST)
693 {
694 chunking_state = CHUNKING_OFFERED;
695 DEBUG(D_receive) debug_printf("chunking state %d\n", (int)chunking_state);
696 }
697 }
698
699
700
701
702 /*************************************************
703 * SMTP version of ungetc() *
704 *************************************************/
705
706 /* Puts a character back in the input buffer. Only ever
707 called once.
708
709 Arguments:
710 ch the character
711
712 Returns: the character
713 */
714
715 int
716 smtp_ungetc(int ch)
717 {
718 *--smtp_inptr = ch;
719 return ch;
720 }
721
722
723 int
724 bdat_ungetc(int ch)
725 {
726 chunking_data_left++;
727 return lwr_receive_ungetc(ch);
728 }
729
730
731
732 /*************************************************
733 * SMTP version of feof() *
734 *************************************************/
735
736 /* Tests for a previous EOF
737
738 Arguments: none
739 Returns: non-zero if the eof flag is set
740 */
741
742 int
743 smtp_feof(void)
744 {
745 return smtp_had_eof;
746 }
747
748
749
750
751 /*************************************************
752 * SMTP version of ferror() *
753 *************************************************/
754
755 /* Tests for a previous read error, and returns with errno
756 restored to what it was when the error was detected.
757
758 Arguments: none
759 Returns: non-zero if the error flag is set
760 */
761
762 int
763 smtp_ferror(void)
764 {
765 errno = smtp_had_error;
766 return smtp_had_error;
767 }
768
769
770
771 /*************************************************
772 * Test for characters in the SMTP buffer *
773 *************************************************/
774
775 /* Used at the end of a message
776
777 Arguments: none
778 Returns: TRUE/FALSE
779 */
780
781 BOOL
782 smtp_buffered(void)
783 {
784 return smtp_inptr < smtp_inend;
785 }
786
787
788
789 /*************************************************
790 * Write formatted string to SMTP channel *
791 *************************************************/
792
793 /* This is a separate function so that we don't have to repeat everything for
794 TLS support or debugging. It is global so that the daemon and the
795 authentication functions can use it. It does not return any error indication,
796 because major problems such as dropped connections won't show up till an output
797 flush for non-TLS connections. The smtp_fflush() function is available for
798 checking that: for convenience, TLS output errors are remembered here so that
799 they are also picked up later by smtp_fflush().
800
801 Arguments:
802 format format string
803 more further data expected
804 ... optional arguments
805
806 Returns: nothing
807 */
808
809 void
810 smtp_printf(const char *format, BOOL more, ...)
811 {
812 va_list ap;
813
814 va_start(ap, more);
815 smtp_vprintf(format, more, ap);
816 va_end(ap);
817 }
818
819 /* This is split off so that verify.c:respond_printf() can, in effect, call
820 smtp_printf(), bearing in mind that in C a vararg function can't directly
821 call another vararg function, only a function which accepts a va_list. */
822
823 void
824 smtp_vprintf(const char *format, BOOL more, va_list ap)
825 {
826 BOOL yield;
827
828 yield = string_vformat(big_buffer, big_buffer_size, format, ap);
829
830 DEBUG(D_receive)
831 {
832 void *reset_point = store_get(0);
833 uschar *msg_copy, *cr, *end;
834 msg_copy = string_copy(big_buffer);
835 end = msg_copy + Ustrlen(msg_copy);
836 while ((cr = Ustrchr(msg_copy, '\r')) != NULL) /* lose CRs */
837 memmove(cr, cr + 1, (end--) - cr);
838 debug_printf("SMTP>> %s", msg_copy);
839 store_reset(reset_point);
840 }
841
842 if (!yield)
843 {
844 log_write(0, LOG_MAIN|LOG_PANIC, "string too large in smtp_printf()");
845 smtp_closedown(US"Unexpected error");
846 exim_exit(EXIT_FAILURE, NULL);
847 }
848
849 /* If this is the first output for a (non-batch) RCPT command, see if all RCPTs
850 have had the same. Note: this code is also present in smtp_respond(). It would
851 be tidier to have it only in one place, but when it was added, it was easier to
852 do it that way, so as not to have to mess with the code for the RCPT command,
853 which sometimes uses smtp_printf() and sometimes smtp_respond(). */
854
855 if (rcpt_in_progress)
856 {
857 if (rcpt_smtp_response == NULL)
858 rcpt_smtp_response = string_copy(big_buffer);
859 else if (rcpt_smtp_response_same &&
860 Ustrcmp(rcpt_smtp_response, big_buffer) != 0)
861 rcpt_smtp_response_same = FALSE;
862 rcpt_in_progress = FALSE;
863 }
864
865 /* Now write the string */
866
867 #ifdef SUPPORT_TLS
868 if (tls_in.active >= 0)
869 {
870 if (tls_write(TRUE, big_buffer, Ustrlen(big_buffer), more) < 0)
871 smtp_write_error = -1;
872 }
873 else
874 #endif
875
876 if (fprintf(smtp_out, "%s", big_buffer) < 0) smtp_write_error = -1;
877 }
878
879
880
881 /*************************************************
882 * Flush SMTP out and check for error *
883 *************************************************/
884
885 /* This function isn't currently used within Exim (it detects errors when it
886 tries to read the next SMTP input), but is available for use in local_scan().
887 For non-TLS connections, it flushes the output and checks for errors. For
888 TLS-connections, it checks for a previously-detected TLS write error.
889
890 Arguments: none
891 Returns: 0 for no error; -1 after an error
892 */
893
894 int
895 smtp_fflush(void)
896 {
897 if (tls_in.active < 0 && fflush(smtp_out) != 0) smtp_write_error = -1;
898 return smtp_write_error;
899 }
900
901
902
903 /*************************************************
904 * SMTP command read timeout *
905 *************************************************/
906
907 /* Signal handler for timing out incoming SMTP commands. This attempts to
908 finish off tidily.
909
910 Argument: signal number (SIGALRM)
911 Returns: nothing
912 */
913
914 static void
915 command_timeout_handler(int sig)
916 {
917 sig = sig; /* Keep picky compilers happy */
918 log_write(L_lost_incoming_connection,
919 LOG_MAIN, "SMTP command timeout on%s connection from %s",
920 (tls_in.active >= 0)? " TLS" : "",
921 host_and_ident(FALSE));
922 if (smtp_batched_input)
923 moan_smtp_batch(NULL, "421 SMTP command timeout"); /* Does not return */
924 smtp_notquit_exit(US"command-timeout", US"421",
925 US"%s: SMTP command timeout - closing connection", smtp_active_hostname);
926 exim_exit(EXIT_FAILURE, US"receiving");
927 }
928
929
930
931 /*************************************************
932 * SIGTERM received *
933 *************************************************/
934
935 /* Signal handler for handling SIGTERM. Again, try to finish tidily.
936
937 Argument: signal number (SIGTERM)
938 Returns: nothing
939 */
940
941 static void
942 command_sigterm_handler(int sig)
943 {
944 sig = sig; /* Keep picky compilers happy */
945 log_write(0, LOG_MAIN, "%s closed after SIGTERM", smtp_get_connection_info());
946 if (smtp_batched_input)
947 moan_smtp_batch(NULL, "421 SIGTERM received"); /* Does not return */
948 smtp_notquit_exit(US"signal-exit", US"421",
949 US"%s: Service not available - closing connection", smtp_active_hostname);
950 exim_exit(EXIT_FAILURE, US"receiving");
951 }
952
953
954
955
956 #ifdef SUPPORT_PROXY
957 /*************************************************
958 * Restore socket timeout to previous value *
959 *************************************************/
960 /* If the previous value was successfully retrieved, restore
961 it before returning control to the non-proxy routines
962
963 Arguments: fd - File descriptor for input
964 get_ok - Successfully retrieved previous values
965 tvtmp - Time struct with previous values
966 vslen - Length of time struct
967 Returns: none
968 */
969 static void
970 restore_socket_timeout(int fd, int get_ok, struct timeval * tvtmp, socklen_t vslen)
971 {
972 if (get_ok == 0)
973 (void) setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, CS tvtmp, vslen);
974 }
975
976 /*************************************************
977 * Check if host is required proxy host *
978 *************************************************/
979 /* The function determines if inbound host will be a regular smtp host
980 or if it is configured that it must use Proxy Protocol. A local
981 connection cannot.
982
983 Arguments: none
984 Returns: bool
985 */
986
987 static BOOL
988 check_proxy_protocol_host()
989 {
990 int rc;
991
992 if ( sender_host_address
993 && (rc = verify_check_this_host(CUSS &hosts_proxy, NULL, NULL,
994 sender_host_address, NULL)) == OK)
995 {
996 DEBUG(D_receive)
997 debug_printf("Detected proxy protocol configured host\n");
998 proxy_session = TRUE;
999 }
1000 return proxy_session;
1001 }
1002
1003
1004 /*************************************************
1005 * Read data until newline or end of buffer *
1006 *************************************************/
1007 /* While SMTP is server-speaks-first, TLS is client-speaks-first, so we can't
1008 read an entire buffer and assume there will be nothing past a proxy protocol
1009 header. Our approach normally is to use stdio, but again that relies upon
1010 "STARTTLS\r\n" and a server response before the client starts TLS handshake, or
1011 reading _nothing_ before client TLS handshake. So we don't want to use the
1012 usual buffering reads which may read enough to block TLS starting.
1013
1014 So unfortunately we're down to "read one byte at a time, with a syscall each,
1015 and expect a little overhead", for all proxy-opened connections which are v1,
1016 just to handle the TLS-on-connect case. Since SSL functions wrap the
1017 underlying fd, we can't assume that we can feed them any already-read content.
1018
1019 We need to know where to read to, the max capacity, and we'll read until we
1020 get a CR and one more character. Let the caller scream if it's CR+!LF.
1021
1022 Return the amount read.
1023 */
1024
1025 static int
1026 swallow_until_crlf(int fd, uschar *base, int already, int capacity)
1027 {
1028 uschar *to = base + already;
1029 uschar *cr;
1030 int have = 0;
1031 int ret;
1032 int last = 0;
1033
1034 /* For "PROXY UNKNOWN\r\n" we, at time of writing, expect to have read
1035 up through the \r; for the _normal_ case, we haven't yet seen the \r. */
1036
1037 cr = memchr(base, '\r', already);
1038 if (cr != NULL)
1039 {
1040 if ((cr - base) < already - 1)
1041 {
1042 /* \r and presumed \n already within what we have; probably not
1043 actually proxy protocol, but abort cleanly. */
1044 return 0;
1045 }
1046 /* \r is last character read, just need one more. */
1047 last = 1;
1048 }
1049
1050 while (capacity > 0)
1051 {
1052 do { ret = recv(fd, to, 1, 0); } while (ret == -1 && errno == EINTR);
1053 if (ret == -1)
1054 return -1;
1055 have++;
1056 if (last)
1057 return have;
1058 if (*to == '\r')
1059 last = 1;
1060 capacity--;
1061 to++;
1062 }
1063
1064 /* reached end without having room for a final newline, abort */
1065 errno = EOVERFLOW;
1066 return -1;
1067 }
1068
1069 /*************************************************
1070 * Setup host for proxy protocol *
1071 *************************************************/
1072 /* The function configures the connection based on a header from the
1073 inbound host to use Proxy Protocol. The specification is very exact
1074 so exit with an error if do not find the exact required pieces. This
1075 includes an incorrect number of spaces separating args.
1076
1077 Arguments: none
1078 Returns: Boolean success
1079 */
1080
1081 static void
1082 setup_proxy_protocol_host()
1083 {
1084 union {
1085 struct {
1086 uschar line[108];
1087 } v1;
1088 struct {
1089 uschar sig[12];
1090 uint8_t ver_cmd;
1091 uint8_t fam;
1092 uint16_t len;
1093 union {
1094 struct { /* TCP/UDP over IPv4, len = 12 */
1095 uint32_t src_addr;
1096 uint32_t dst_addr;
1097 uint16_t src_port;
1098 uint16_t dst_port;
1099 } ip4;
1100 struct { /* TCP/UDP over IPv6, len = 36 */
1101 uint8_t src_addr[16];
1102 uint8_t dst_addr[16];
1103 uint16_t src_port;
1104 uint16_t dst_port;
1105 } ip6;
1106 struct { /* AF_UNIX sockets, len = 216 */
1107 uschar src_addr[108];
1108 uschar dst_addr[108];
1109 } unx;
1110 } addr;
1111 } v2;
1112 } hdr;
1113
1114 /* Temp variables used in PPv2 address:port parsing */
1115 uint16_t tmpport;
1116 char tmpip[INET_ADDRSTRLEN];
1117 struct sockaddr_in tmpaddr;
1118 char tmpip6[INET6_ADDRSTRLEN];
1119 struct sockaddr_in6 tmpaddr6;
1120
1121 /* We can't read "all data until end" because while SMTP is
1122 server-speaks-first, the TLS handshake is client-speaks-first, so for
1123 TLS-on-connect ports the proxy protocol header will usually be immediately
1124 followed by a TLS handshake, and with N TLS libraries, we can't reliably
1125 reinject data for reading by those. So instead we first read "enough to be
1126 safely read within the header, and figure out how much more to read".
1127 For v1 we will later read to the end-of-line, for v2 we will read based upon
1128 the stated length.
1129
1130 The v2 sig is 12 octets, and another 4 gets us the length, so we know how much
1131 data is needed total. For v1, where the line looks like:
1132 PROXY TCPn L3src L3dest SrcPort DestPort \r\n
1133
1134 However, for v1 there's also `PROXY UNKNOWN\r\n` which is only 15 octets.
1135 We seem to support that. So, if we read 14 octets then we can tell if we're
1136 v2 or v1. If we're v1, we can continue reading as normal.
1137
1138 If we're v2, we can't slurp up the entire header. We need the length in the
1139 15th & 16th octets, then to read everything after that.
1140
1141 So to safely handle v1 and v2, with client-sent-first supported correctly,
1142 we have to do a minimum of 3 read calls, not 1. Eww.
1143 */
1144
1145 #define PROXY_INITIAL_READ 14
1146 #define PROXY_V2_HEADER_SIZE 16
1147 #if PROXY_INITIAL_READ > PROXY_V2_HEADER_SIZE
1148 # error Code bug in sizes of data to read for proxy usage
1149 #endif
1150
1151 int get_ok = 0;
1152 int size, ret;
1153 int fd = fileno(smtp_in);
1154 const char v2sig[12] = "\x0D\x0A\x0D\x0A\x00\x0D\x0A\x51\x55\x49\x54\x0A";
1155 uschar * iptype; /* To display debug info */
1156 struct timeval tv;
1157 struct timeval tvtmp;
1158 socklen_t vslen = sizeof(struct timeval);
1159 BOOL yield = FALSE;
1160
1161 /* Save current socket timeout values */
1162 get_ok = getsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, CS &tvtmp, &vslen);
1163
1164 /* Proxy Protocol host must send header within a short time
1165 (default 3 seconds) or it's considered invalid */
1166 tv.tv_sec = PROXY_NEGOTIATION_TIMEOUT_SEC;
1167 tv.tv_usec = PROXY_NEGOTIATION_TIMEOUT_USEC;
1168 if (setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, CS &tv, sizeof(tv)) < 0)
1169 goto bad;
1170
1171 do
1172 {
1173 /* The inbound host was declared to be a Proxy Protocol host, so
1174 don't do a PEEK into the data, actually slurp up enough to be
1175 "safe". Can't take it all because TLS-on-connect clients follow
1176 immediately with TLS handshake. */
1177 ret = recv(fd, &hdr, PROXY_INITIAL_READ, 0);
1178 }
1179 while (ret == -1 && errno == EINTR);
1180
1181 if (ret == -1)
1182 goto proxyfail;
1183
1184 /* For v2, handle reading the length, and then the rest. */
1185 if ((ret == PROXY_INITIAL_READ) && (memcmp(&hdr.v2, v2sig, sizeof(v2sig)) == 0))
1186 {
1187 int retmore;
1188 uint8_t ver;
1189
1190 /* First get the length fields. */
1191 do
1192 {
1193 retmore = recv(fd, (uschar*)&hdr + ret, PROXY_V2_HEADER_SIZE - PROXY_INITIAL_READ, 0);
1194 } while (retmore == -1 && errno == EINTR);
1195 if (retmore == -1)
1196 goto proxyfail;
1197 ret += retmore;
1198
1199 ver = (hdr.v2.ver_cmd & 0xf0) >> 4;
1200
1201 /* May 2014: haproxy combined the version and command into one byte to
1202 allow two full bytes for the length field in order to proxy SSL
1203 connections. SSL Proxy is not supported in this version of Exim, but
1204 must still separate values here. */
1205
1206 if (ver != 0x02)
1207 {
1208 DEBUG(D_receive) debug_printf("Invalid Proxy Protocol version: %d\n", ver);
1209 goto proxyfail;
1210 }
1211
1212 /* The v2 header will always be 16 bytes per the spec. */
1213 size = 16 + ntohs(hdr.v2.len);
1214 DEBUG(D_receive) debug_printf("Detected PROXYv2 header, size %d (limit %d)\n",
1215 size, (int)sizeof(hdr));
1216
1217 /* We should now have 16 octets (PROXY_V2_HEADER_SIZE), and we know the total
1218 amount that we need. Double-check that the size is not unreasonable, then
1219 get the rest. */
1220 if (size > sizeof(hdr))
1221 {
1222 DEBUG(D_receive) debug_printf("PROXYv2 header size unreasonably large; security attack?\n");
1223 goto proxyfail;
1224 }
1225
1226 do
1227 {
1228 do
1229 {
1230 retmore = recv(fd, (uschar*)&hdr + ret, size-ret, 0);
1231 } while (retmore == -1 && errno == EINTR);
1232 if (retmore == -1)
1233 goto proxyfail;
1234 ret += retmore;
1235 DEBUG(D_receive) debug_printf("PROXYv2: have %d/%d required octets\n", ret, size);
1236 } while (ret < size);
1237
1238 } /* end scope for getting rest of data for v2 */
1239
1240 /* At this point: if PROXYv2, we've read the exact size required for all data;
1241 if PROXYv1 then we've read "less than required for any valid line" and should
1242 read the rest". */
1243
1244 if (ret >= 16 && memcmp(&hdr.v2, v2sig, 12) == 0)
1245 {
1246 uint8_t cmd = (hdr.v2.ver_cmd & 0x0f);
1247
1248 switch (cmd)
1249 {
1250 case 0x01: /* PROXY command */
1251 switch (hdr.v2.fam)
1252 {
1253 case 0x11: /* TCPv4 address type */
1254 iptype = US"IPv4";
1255 tmpaddr.sin_addr.s_addr = hdr.v2.addr.ip4.src_addr;
1256 inet_ntop(AF_INET, &tmpaddr.sin_addr, CS &tmpip, sizeof(tmpip));
1257 if (!string_is_ip_address(US tmpip, NULL))
1258 {
1259 DEBUG(D_receive) debug_printf("Invalid %s source IP\n", iptype);
1260 goto proxyfail;
1261 }
1262 proxy_local_address = sender_host_address;
1263 sender_host_address = string_copy(US tmpip);
1264 tmpport = ntohs(hdr.v2.addr.ip4.src_port);
1265 proxy_local_port = sender_host_port;
1266 sender_host_port = tmpport;
1267 /* Save dest ip/port */
1268 tmpaddr.sin_addr.s_addr = hdr.v2.addr.ip4.dst_addr;
1269 inet_ntop(AF_INET, &tmpaddr.sin_addr, CS &tmpip, sizeof(tmpip));
1270 if (!string_is_ip_address(US tmpip, NULL))
1271 {
1272 DEBUG(D_receive) debug_printf("Invalid %s dest port\n", iptype);
1273 goto proxyfail;
1274 }
1275 proxy_external_address = string_copy(US tmpip);
1276 tmpport = ntohs(hdr.v2.addr.ip4.dst_port);
1277 proxy_external_port = tmpport;
1278 goto done;
1279 case 0x21: /* TCPv6 address type */
1280 iptype = US"IPv6";
1281 memmove(tmpaddr6.sin6_addr.s6_addr, hdr.v2.addr.ip6.src_addr, 16);
1282 inet_ntop(AF_INET6, &tmpaddr6.sin6_addr, CS &tmpip6, sizeof(tmpip6));
1283 if (!string_is_ip_address(US tmpip6, NULL))
1284 {
1285 DEBUG(D_receive) debug_printf("Invalid %s source IP\n", iptype);
1286 goto proxyfail;
1287 }
1288 proxy_local_address = sender_host_address;
1289 sender_host_address = string_copy(US tmpip6);
1290 tmpport = ntohs(hdr.v2.addr.ip6.src_port);
1291 proxy_local_port = sender_host_port;
1292 sender_host_port = tmpport;
1293 /* Save dest ip/port */
1294 memmove(tmpaddr6.sin6_addr.s6_addr, hdr.v2.addr.ip6.dst_addr, 16);
1295 inet_ntop(AF_INET6, &tmpaddr6.sin6_addr, CS &tmpip6, sizeof(tmpip6));
1296 if (!string_is_ip_address(US tmpip6, NULL))
1297 {
1298 DEBUG(D_receive) debug_printf("Invalid %s dest port\n", iptype);
1299 goto proxyfail;
1300 }
1301 proxy_external_address = string_copy(US tmpip6);
1302 tmpport = ntohs(hdr.v2.addr.ip6.dst_port);
1303 proxy_external_port = tmpport;
1304 goto done;
1305 default:
1306 DEBUG(D_receive)
1307 debug_printf("Unsupported PROXYv2 connection type: 0x%02x\n",
1308 hdr.v2.fam);
1309 goto proxyfail;
1310 }
1311 /* Unsupported protocol, keep local connection address */
1312 break;
1313 case 0x00: /* LOCAL command */
1314 /* Keep local connection address for LOCAL */
1315 iptype = US"local";
1316 break;
1317 default:
1318 DEBUG(D_receive)
1319 debug_printf("Unsupported PROXYv2 command: 0x%x\n", cmd);
1320 goto proxyfail;
1321 }
1322 }
1323 else if (ret >= 8 && memcmp(hdr.v1.line, "PROXY", 5) == 0)
1324 {
1325 uschar *p;
1326 uschar *end;
1327 uschar *sp; /* Utility variables follow */
1328 int tmp_port;
1329 int r2;
1330 char *endc;
1331
1332 /* get the rest of the line */
1333 r2 = swallow_until_crlf(fd, (uschar*)&hdr, ret, sizeof(hdr)-ret);
1334 if (r2 == -1)
1335 goto proxyfail;
1336 ret += r2;
1337
1338 p = string_copy(hdr.v1.line);
1339 end = memchr(p, '\r', ret - 1);
1340
1341 if (!end || (end == (uschar*)&hdr + ret) || end[1] != '\n')
1342 {
1343 DEBUG(D_receive) debug_printf("Partial or invalid PROXY header\n");
1344 goto proxyfail;
1345 }
1346 *end = '\0'; /* Terminate the string */
1347 size = end + 2 - p; /* Skip header + CRLF */
1348 DEBUG(D_receive) debug_printf("Detected PROXYv1 header\n");
1349 DEBUG(D_receive) debug_printf("Bytes read not within PROXY header: %d\n", ret - size);
1350 /* Step through the string looking for the required fields. Ensure
1351 strict adherence to required formatting, exit for any error. */
1352 p += 5;
1353 if (!isspace(*(p++)))
1354 {
1355 DEBUG(D_receive) debug_printf("Missing space after PROXY command\n");
1356 goto proxyfail;
1357 }
1358 if (!Ustrncmp(p, CCS"TCP4", 4))
1359 iptype = US"IPv4";
1360 else if (!Ustrncmp(p,CCS"TCP6", 4))
1361 iptype = US"IPv6";
1362 else if (!Ustrncmp(p,CCS"UNKNOWN", 7))
1363 {
1364 iptype = US"Unknown";
1365 goto done;
1366 }
1367 else
1368 {
1369 DEBUG(D_receive) debug_printf("Invalid TCP type\n");
1370 goto proxyfail;
1371 }
1372
1373 p += Ustrlen(iptype);
1374 if (!isspace(*(p++)))
1375 {
1376 DEBUG(D_receive) debug_printf("Missing space after TCP4/6 command\n");
1377 goto proxyfail;
1378 }
1379 /* Find the end of the arg */
1380 if ((sp = Ustrchr(p, ' ')) == NULL)
1381 {
1382 DEBUG(D_receive)
1383 debug_printf("Did not find proxied src %s\n", iptype);
1384 goto proxyfail;
1385 }
1386 *sp = '\0';
1387 if(!string_is_ip_address(p, NULL))
1388 {
1389 DEBUG(D_receive)
1390 debug_printf("Proxied src arg is not an %s address\n", iptype);
1391 goto proxyfail;
1392 }
1393 proxy_local_address = sender_host_address;
1394 sender_host_address = p;
1395 p = sp + 1;
1396 if ((sp = Ustrchr(p, ' ')) == NULL)
1397 {
1398 DEBUG(D_receive)
1399 debug_printf("Did not find proxy dest %s\n", iptype);
1400 goto proxyfail;
1401 }
1402 *sp = '\0';
1403 if(!string_is_ip_address(p, NULL))
1404 {
1405 DEBUG(D_receive)
1406 debug_printf("Proxy dest arg is not an %s address\n", iptype);
1407 goto proxyfail;
1408 }
1409 proxy_external_address = p;
1410 p = sp + 1;
1411 if ((sp = Ustrchr(p, ' ')) == NULL)
1412 {
1413 DEBUG(D_receive) debug_printf("Did not find proxied src port\n");
1414 goto proxyfail;
1415 }
1416 *sp = '\0';
1417 tmp_port = strtol(CCS p, &endc, 10);
1418 if (*endc || tmp_port == 0)
1419 {
1420 DEBUG(D_receive)
1421 debug_printf("Proxied src port '%s' not an integer\n", p);
1422 goto proxyfail;
1423 }
1424 proxy_local_port = sender_host_port;
1425 sender_host_port = tmp_port;
1426 p = sp + 1;
1427 if ((sp = Ustrchr(p, '\0')) == NULL)
1428 {
1429 DEBUG(D_receive) debug_printf("Did not find proxy dest port\n");
1430 goto proxyfail;
1431 }
1432 tmp_port = strtol(CCS p, &endc, 10);
1433 if (*endc || tmp_port == 0)
1434 {
1435 DEBUG(D_receive)
1436 debug_printf("Proxy dest port '%s' not an integer\n", p);
1437 goto proxyfail;
1438 }
1439 proxy_external_port = tmp_port;
1440 /* Already checked for /r /n above. Good V1 header received. */
1441 }
1442 else
1443 {
1444 /* Wrong protocol */
1445 DEBUG(D_receive) debug_printf("Invalid proxy protocol version negotiation\n");
1446 (void) swallow_until_crlf(fd, (uschar*)&hdr, ret, sizeof(hdr)-ret);
1447 goto proxyfail;
1448 }
1449
1450 done:
1451 DEBUG(D_receive)
1452 debug_printf("Valid %s sender from Proxy Protocol header\n", iptype);
1453 yield = proxy_session;
1454
1455 /* Don't flush any potential buffer contents. Any input on proxyfail
1456 should cause a synchronization failure */
1457
1458 proxyfail:
1459 restore_socket_timeout(fd, get_ok, &tvtmp, vslen);
1460
1461 bad:
1462 if (yield)
1463 {
1464 sender_host_name = NULL;
1465 (void) host_name_lookup();
1466 host_build_sender_fullhost();
1467 }
1468 else
1469 {
1470 proxy_session_failed = TRUE;
1471 DEBUG(D_receive)
1472 debug_printf("Failure to extract proxied host, only QUIT allowed\n");
1473 }
1474
1475 return;
1476 }
1477 #endif
1478
1479 /*************************************************
1480 * Read one command line *
1481 *************************************************/
1482
1483 /* Strictly, SMTP commands coming over the net are supposed to end with CRLF.
1484 There are sites that don't do this, and in any case internal SMTP probably
1485 should check only for LF. Consequently, we check here for LF only. The line
1486 ends up with [CR]LF removed from its end. If we get an overlong line, treat as
1487 an unknown command. The command is read into the global smtp_cmd_buffer so that
1488 it is available via $smtp_command.
1489
1490 The character reading routine sets up a timeout for each block actually read
1491 from the input (which may contain more than one command). We set up a special
1492 signal handler that closes down the session on a timeout. Control does not
1493 return when it runs.
1494
1495 Arguments:
1496 check_sync if TRUE, check synchronization rules if global option is TRUE
1497 buffer_lim maximum to buffer in lower layer
1498
1499 Returns: a code identifying the command (enumerated above)
1500 */
1501
1502 static int
1503 smtp_read_command(BOOL check_sync, unsigned buffer_lim)
1504 {
1505 int c;
1506 int ptr = 0;
1507 smtp_cmd_list *p;
1508 BOOL hadnull = FALSE;
1509
1510 os_non_restarting_signal(SIGALRM, command_timeout_handler);
1511
1512 while ((c = (receive_getc)(buffer_lim)) != '\n' && c != EOF)
1513 {
1514 if (ptr >= SMTP_CMD_BUFFER_SIZE)
1515 {
1516 os_non_restarting_signal(SIGALRM, sigalrm_handler);
1517 return OTHER_CMD;
1518 }
1519 if (c == 0)
1520 {
1521 hadnull = TRUE;
1522 c = '?';
1523 }
1524 smtp_cmd_buffer[ptr++] = c;
1525 }
1526
1527 receive_linecount++; /* For BSMTP errors */
1528 os_non_restarting_signal(SIGALRM, sigalrm_handler);
1529
1530 /* If hit end of file, return pseudo EOF command. Whether we have a
1531 part-line already read doesn't matter, since this is an error state. */
1532
1533 if (c == EOF) return EOF_CMD;
1534
1535 /* Remove any CR and white space at the end of the line, and terminate the
1536 string. */
1537
1538 while (ptr > 0 && isspace(smtp_cmd_buffer[ptr-1])) ptr--;
1539 smtp_cmd_buffer[ptr] = 0;
1540
1541 DEBUG(D_receive) debug_printf("SMTP<< %s\n", smtp_cmd_buffer);
1542
1543 /* NULLs are not allowed in SMTP commands */
1544
1545 if (hadnull) return BADCHAR_CMD;
1546
1547 /* Scan command list and return identity, having set the data pointer
1548 to the start of the actual data characters. Check for SMTP synchronization
1549 if required. */
1550
1551 for (p = cmd_list; p < cmd_list_end; p++)
1552 {
1553 #ifdef SUPPORT_PROXY
1554 /* Only allow QUIT command if Proxy Protocol parsing failed */
1555 if (proxy_session && proxy_session_failed && p->cmd != QUIT_CMD)
1556 continue;
1557 #endif
1558 if ( p->len
1559 && strncmpic(smtp_cmd_buffer, US p->name, p->len) == 0
1560 && ( smtp_cmd_buffer[p->len-1] == ':' /* "mail from:" or "rcpt to:" */
1561 || smtp_cmd_buffer[p->len] == 0
1562 || smtp_cmd_buffer[p->len] == ' '
1563 ) )
1564 {
1565 if (smtp_inptr < smtp_inend && /* Outstanding input */
1566 p->cmd < sync_cmd_limit && /* Command should sync */
1567 check_sync && /* Local flag set */
1568 smtp_enforce_sync && /* Global flag set */
1569 sender_host_address != NULL && /* Not local input */
1570 !sender_host_notsocket) /* Really is a socket */
1571 return BADSYN_CMD;
1572
1573 /* The variables $smtp_command and $smtp_command_argument point into the
1574 unmodified input buffer. A copy of the latter is taken for actual
1575 processing, so that it can be chopped up into separate parts if necessary,
1576 for example, when processing a MAIL command options such as SIZE that can
1577 follow the sender address. */
1578
1579 smtp_cmd_argument = smtp_cmd_buffer + p->len;
1580 while (isspace(*smtp_cmd_argument)) smtp_cmd_argument++;
1581 Ustrcpy(smtp_data_buffer, smtp_cmd_argument);
1582 smtp_cmd_data = smtp_data_buffer;
1583
1584 /* Count non-mail commands from those hosts that are controlled in this
1585 way. The default is all hosts. We don't waste effort checking the list
1586 until we get a non-mail command, but then cache the result to save checking
1587 again. If there's a DEFER while checking the host, assume it's in the list.
1588
1589 Note that one instance of RSET, EHLO/HELO, and STARTTLS is allowed at the
1590 start of each incoming message by fiddling with the value in the table. */
1591
1592 if (!p->is_mail_cmd)
1593 {
1594 if (count_nonmail == TRUE_UNSET) count_nonmail =
1595 verify_check_host(&smtp_accept_max_nonmail_hosts) != FAIL;
1596 if (count_nonmail && ++nonmail_command_count > smtp_accept_max_nonmail)
1597 return TOO_MANY_NONMAIL_CMD;
1598 }
1599
1600 /* If there is data for a command that does not expect it, generate the
1601 error here. */
1602
1603 return (p->has_arg || *smtp_cmd_data == 0)? p->cmd : BADARG_CMD;
1604 }
1605 }
1606
1607 #ifdef SUPPORT_PROXY
1608 /* Only allow QUIT command if Proxy Protocol parsing failed */
1609 if (proxy_session && proxy_session_failed)
1610 return PROXY_FAIL_IGNORE_CMD;
1611 #endif
1612
1613 /* Enforce synchronization for unknown commands */
1614
1615 if ( smtp_inptr < smtp_inend /* Outstanding input */
1616 && check_sync /* Local flag set */
1617 && smtp_enforce_sync /* Global flag set */
1618 && sender_host_address /* Not local input */
1619 && !sender_host_notsocket) /* Really is a socket */
1620 return BADSYN_CMD;
1621
1622 return OTHER_CMD;
1623 }
1624
1625
1626
1627 /*************************************************
1628 * Forced closedown of call *
1629 *************************************************/
1630
1631 /* This function is called from log.c when Exim is dying because of a serious
1632 disaster, and also from some other places. If an incoming non-batched SMTP
1633 channel is open, it swallows the rest of the incoming message if in the DATA
1634 phase, sends the reply string, and gives an error to all subsequent commands
1635 except QUIT. The existence of an SMTP call is detected by the non-NULLness of
1636 smtp_in.
1637
1638 Arguments:
1639 message SMTP reply string to send, excluding the code
1640
1641 Returns: nothing
1642 */
1643
1644 void
1645 smtp_closedown(uschar *message)
1646 {
1647 if (!smtp_in || smtp_batched_input) return;
1648 receive_swallow_smtp();
1649 smtp_printf("421 %s\r\n", FALSE, message);
1650
1651 for (;;) switch(smtp_read_command(FALSE, GETC_BUFFER_UNLIMITED))
1652 {
1653 case EOF_CMD:
1654 return;
1655
1656 case QUIT_CMD:
1657 smtp_printf("221 %s closing connection\r\n", FALSE, smtp_active_hostname);
1658 mac_smtp_fflush();
1659 return;
1660
1661 case RSET_CMD:
1662 smtp_printf("250 Reset OK\r\n", FALSE);
1663 break;
1664
1665 default:
1666 smtp_printf("421 %s\r\n", FALSE, message);
1667 break;
1668 }
1669 }
1670
1671
1672
1673
1674 /*************************************************
1675 * Set up connection info for logging *
1676 *************************************************/
1677
1678 /* This function is called when logging information about an SMTP connection.
1679 It sets up appropriate source information, depending on the type of connection.
1680 If sender_fullhost is NULL, we are at a very early stage of the connection;
1681 just use the IP address.
1682
1683 Argument: none
1684 Returns: a string describing the connection
1685 */
1686
1687 uschar *
1688 smtp_get_connection_info(void)
1689 {
1690 const uschar * hostname = sender_fullhost
1691 ? sender_fullhost : sender_host_address;
1692
1693 if (host_checking)
1694 return string_sprintf("SMTP connection from %s", hostname);
1695
1696 if (sender_host_unknown || sender_host_notsocket)
1697 return string_sprintf("SMTP connection from %s", sender_ident);
1698
1699 if (is_inetd)
1700 return string_sprintf("SMTP connection from %s (via inetd)", hostname);
1701
1702 if (LOGGING(incoming_interface) && interface_address != NULL)
1703 return string_sprintf("SMTP connection from %s I=[%s]:%d", hostname,
1704 interface_address, interface_port);
1705
1706 return string_sprintf("SMTP connection from %s", hostname);
1707 }
1708
1709
1710
1711 #ifdef SUPPORT_TLS
1712 /* Append TLS-related information to a log line
1713
1714 Arguments:
1715 g String under construction: allocated string to extend, or NULL
1716
1717 Returns: Allocated string or NULL
1718 */
1719 static gstring *
1720 s_tlslog(gstring * g)
1721 {
1722 if (LOGGING(tls_cipher) && tls_in.cipher)
1723 g = string_append(g, 2, US" X=", tls_in.cipher);
1724 if (LOGGING(tls_certificate_verified) && tls_in.cipher)
1725 g = string_append(g, 2, US" CV=", tls_in.certificate_verified? "yes":"no");
1726 if (LOGGING(tls_peerdn) && tls_in.peerdn)
1727 g = string_append(g, 3, US" DN=\"", string_printing(tls_in.peerdn), US"\"");
1728 if (LOGGING(tls_sni) && tls_in.sni)
1729 g = string_append(g, 3, US" SNI=\"", string_printing(tls_in.sni), US"\"");
1730 return g;
1731 }
1732 #endif
1733
1734 /*************************************************
1735 * Log lack of MAIL if so configured *
1736 *************************************************/
1737
1738 /* This function is called when an SMTP session ends. If the log selector
1739 smtp_no_mail is set, write a log line giving some details of what has happened
1740 in the SMTP session.
1741
1742 Arguments: none
1743 Returns: nothing
1744 */
1745
1746 void
1747 smtp_log_no_mail(void)
1748 {
1749 int i;
1750 uschar * sep, * s;
1751 gstring * g = NULL;
1752
1753 if (smtp_mailcmd_count > 0 || !LOGGING(smtp_no_mail))
1754 return;
1755
1756 if (sender_host_authenticated)
1757 {
1758 g = string_append(g, 2, US" A=", sender_host_authenticated);
1759 if (authenticated_id) g = string_append(g, 2, US":", authenticated_id);
1760 }
1761
1762 #ifdef SUPPORT_TLS
1763 g = s_tlslog(g);
1764 #endif
1765
1766 sep = smtp_connection_had[SMTP_HBUFF_SIZE-1] != SCH_NONE ? US" C=..." : US" C=";
1767
1768 for (i = smtp_ch_index; i < SMTP_HBUFF_SIZE; i++)
1769 if (smtp_connection_had[i] != SCH_NONE)
1770 {
1771 g = string_append(g, 2, sep, smtp_names[smtp_connection_had[i]]);
1772 sep = US",";
1773 }
1774
1775 for (i = 0; i < smtp_ch_index; i++)
1776 {
1777 g = string_append(g, 2, sep, smtp_names[smtp_connection_had[i]]);
1778 sep = US",";
1779 }
1780
1781 if (!(s = string_from_gstring(g))) s = US"";
1782
1783 log_write(0, LOG_MAIN, "no MAIL in %sSMTP connection from %s D=%s%s",
1784 tcp_in_fastopen ? US"TFO " : US"",
1785 host_and_ident(FALSE), string_timesince(&smtp_connection_start), s);
1786 }
1787
1788
1789 /* Return list of recent smtp commands */
1790
1791 uschar *
1792 smtp_cmd_hist(void)
1793 {
1794 int i;
1795 gstring * list = NULL;
1796 uschar * s;
1797
1798 for (i = smtp_ch_index; i < SMTP_HBUFF_SIZE; i++)
1799 if (smtp_connection_had[i] != SCH_NONE)
1800 list = string_append_listele(list, ',', smtp_names[smtp_connection_had[i]]);
1801
1802 for (i = 0; i < smtp_ch_index; i++)
1803 list = string_append_listele(list, ',', smtp_names[smtp_connection_had[i]]);
1804
1805 s = string_from_gstring(list);
1806 return s ? s : US"";
1807 }
1808
1809
1810
1811
1812 /*************************************************
1813 * Check HELO line and set sender_helo_name *
1814 *************************************************/
1815
1816 /* Check the format of a HELO line. The data for HELO/EHLO is supposed to be
1817 the domain name of the sending host, or an ip literal in square brackets. The
1818 argument is placed in sender_helo_name, which is in malloc store, because it
1819 must persist over multiple incoming messages. If helo_accept_junk is set, this
1820 host is permitted to send any old junk (needed for some broken hosts).
1821 Otherwise, helo_allow_chars can be used for rogue characters in general
1822 (typically people want to let in underscores).
1823
1824 Argument:
1825 s the data portion of the line (already past any white space)
1826
1827 Returns: TRUE or FALSE
1828 */
1829
1830 static BOOL
1831 check_helo(uschar *s)
1832 {
1833 uschar *start = s;
1834 uschar *end = s + Ustrlen(s);
1835 BOOL yield = helo_accept_junk;
1836
1837 /* Discard any previous helo name */
1838
1839 if (sender_helo_name)
1840 {
1841 store_free(sender_helo_name);
1842 sender_helo_name = NULL;
1843 }
1844
1845 /* Skip tests if junk is permitted. */
1846
1847 if (!yield)
1848
1849 /* Allow the new standard form for IPv6 address literals, namely,
1850 [IPv6:....], and because someone is bound to use it, allow an equivalent
1851 IPv4 form. Allow plain addresses as well. */
1852
1853 if (*s == '[')
1854 {
1855 if (end[-1] == ']')
1856 {
1857 end[-1] = 0;
1858 if (strncmpic(s, US"[IPv6:", 6) == 0)
1859 yield = (string_is_ip_address(s+6, NULL) == 6);
1860 else if (strncmpic(s, US"[IPv4:", 6) == 0)
1861 yield = (string_is_ip_address(s+6, NULL) == 4);
1862 else
1863 yield = (string_is_ip_address(s+1, NULL) != 0);
1864 end[-1] = ']';
1865 }
1866 }
1867
1868 /* Non-literals must be alpha, dot, hyphen, plus any non-valid chars
1869 that have been configured (usually underscore - sigh). */
1870
1871 else if (*s)
1872 for (yield = TRUE; *s; s++)
1873 if (!isalnum(*s) && *s != '.' && *s != '-' &&
1874 Ustrchr(helo_allow_chars, *s) == NULL)
1875 {
1876 yield = FALSE;
1877 break;
1878 }
1879
1880 /* Save argument if OK */
1881
1882 if (yield) sender_helo_name = string_copy_malloc(start);
1883 return yield;
1884 }
1885
1886
1887
1888
1889
1890 /*************************************************
1891 * Extract SMTP command option *
1892 *************************************************/
1893
1894 /* This function picks the next option setting off the end of smtp_cmd_data. It
1895 is called for MAIL FROM and RCPT TO commands, to pick off the optional ESMTP
1896 things that can appear there.
1897
1898 Arguments:
1899 name point this at the name
1900 value point this at the data string
1901
1902 Returns: TRUE if found an option
1903 */
1904
1905 static BOOL
1906 extract_option(uschar **name, uschar **value)
1907 {
1908 uschar *n;
1909 uschar *v = smtp_cmd_data + Ustrlen(smtp_cmd_data) - 1;
1910 while (isspace(*v)) v--;
1911 v[1] = 0;
1912 while (v > smtp_cmd_data && *v != '=' && !isspace(*v))
1913 {
1914 /* Take care to not stop at a space embedded in a quoted local-part */
1915
1916 if (*v == '"') do v--; while (*v != '"' && v > smtp_cmd_data+1);
1917 v--;
1918 }
1919
1920 n = v;
1921 if (*v == '=')
1922 {
1923 while(isalpha(n[-1])) n--;
1924 /* RFC says SP, but TAB seen in wild and other major MTAs accept it */
1925 if (!isspace(n[-1])) return FALSE;
1926 n[-1] = 0;
1927 }
1928 else
1929 {
1930 n++;
1931 if (v == smtp_cmd_data) return FALSE;
1932 }
1933 *v++ = 0;
1934 *name = n;
1935 *value = v;
1936 return TRUE;
1937 }
1938
1939
1940
1941
1942
1943 /*************************************************
1944 * Reset for new message *
1945 *************************************************/
1946
1947 /* This function is called whenever the SMTP session is reset from
1948 within either of the setup functions; also from the daemon loop.
1949
1950 Argument: the stacking pool storage reset point
1951 Returns: nothing
1952 */
1953
1954 void
1955 smtp_reset(void *reset_point)
1956 {
1957 recipients_list = NULL;
1958 rcpt_count = rcpt_defer_count = rcpt_fail_count =
1959 raw_recipients_count = recipients_count = recipients_list_max = 0;
1960 message_linecount = 0;
1961 message_size = -1;
1962 acl_added_headers = NULL;
1963 acl_removed_headers = NULL;
1964 queue_only_policy = FALSE;
1965 rcpt_smtp_response = NULL;
1966 rcpt_smtp_response_same = TRUE;
1967 rcpt_in_progress = FALSE;
1968 deliver_freeze = FALSE; /* Can be set by ACL */
1969 freeze_tell = freeze_tell_config; /* Can be set by ACL */
1970 fake_response = OK; /* Can be set by ACL */
1971 #ifdef WITH_CONTENT_SCAN
1972 no_mbox_unspool = FALSE; /* Can be set by ACL */
1973 #endif
1974 submission_mode = FALSE; /* Can be set by ACL */
1975 suppress_local_fixups = suppress_local_fixups_default; /* Can be set by ACL */
1976 active_local_from_check = local_from_check; /* Can be set by ACL */
1977 active_local_sender_retain = local_sender_retain; /* Can be set by ACL */
1978 sending_ip_address = NULL;
1979 return_path = sender_address = NULL;
1980 sender_data = NULL; /* Can be set by ACL */
1981 deliver_localpart_parent = deliver_localpart_orig = NULL;
1982 deliver_domain_parent = deliver_domain_orig = NULL;
1983 callout_address = NULL;
1984 submission_name = NULL; /* Can be set by ACL */
1985 raw_sender = NULL; /* After SMTP rewrite, before qualifying */
1986 sender_address_unrewritten = NULL; /* Set only after verify rewrite */
1987 sender_verified_list = NULL; /* No senders verified */
1988 memset(sender_address_cache, 0, sizeof(sender_address_cache));
1989 memset(sender_domain_cache, 0, sizeof(sender_domain_cache));
1990
1991 authenticated_sender = NULL;
1992 #ifdef EXPERIMENTAL_BRIGHTMAIL
1993 bmi_run = 0;
1994 bmi_verdicts = NULL;
1995 #endif
1996 dnslist_domain = dnslist_matched = NULL;
1997 #ifndef DISABLE_DKIM
1998 dkim_cur_signer = dkim_signers = NULL;
1999 dkim_disable_verify = dkim_collect_input = FALSE;
2000 #endif
2001 dsn_ret = 0;
2002 dsn_envid = NULL;
2003 deliver_host = deliver_host_address = NULL; /* Can be set by ACL */
2004 #ifndef DISABLE_PRDR
2005 prdr_requested = FALSE;
2006 #endif
2007 #ifdef SUPPORT_SPF
2008 spf_header_comment = spf_received = spf_result = spf_smtp_comment = NULL;
2009 spf_result_guessed = FALSE;
2010 #endif
2011 #ifdef EXPERIMENTAL_DMARC
2012 dmarc_has_been_checked = dmarc_disable_verify = dmarc_enable_forensic = FALSE;
2013 dmarc_domain_policy = dmarc_forensic_sender =
2014 dmarc_history_file = dmarc_status = dmarc_status_text =
2015 dmarc_used_domain = NULL;
2016 #endif
2017 #ifdef EXPERIMENTAL_ARC
2018 arc_state = arc_state_reason = NULL;
2019 #endif
2020 #ifdef SUPPORT_I18N
2021 message_smtputf8 = FALSE;
2022 #endif
2023 body_linecount = body_zerocount = 0;
2024
2025 sender_rate = sender_rate_limit = sender_rate_period = NULL;
2026 ratelimiters_mail = NULL; /* Updated by ratelimit ACL condition */
2027 /* Note that ratelimiters_conn persists across resets. */
2028
2029 /* Reset message ACL variables */
2030
2031 acl_var_m = NULL;
2032
2033 /* The message body variables use malloc store. They may be set if this is
2034 not the first message in an SMTP session and the previous message caused them
2035 to be referenced in an ACL. */
2036
2037 if (message_body)
2038 {
2039 store_free(message_body);
2040 message_body = NULL;
2041 }
2042
2043 if (message_body_end)
2044 {
2045 store_free(message_body_end);
2046 message_body_end = NULL;
2047 }
2048
2049 /* Warning log messages are also saved in malloc store. They are saved to avoid
2050 repetition in the same message, but it seems right to repeat them for different
2051 messages. */
2052
2053 while (acl_warn_logged)
2054 {
2055 string_item *this = acl_warn_logged;
2056 acl_warn_logged = acl_warn_logged->next;
2057 store_free(this);
2058 }
2059 store_reset(reset_point);
2060 }
2061
2062
2063
2064
2065
2066 /*************************************************
2067 * Initialize for incoming batched SMTP message *
2068 *************************************************/
2069
2070 /* This function is called from smtp_setup_msg() in the case when
2071 smtp_batched_input is true. This happens when -bS is used to pass a whole batch
2072 of messages in one file with SMTP commands between them. All errors must be
2073 reported by sending a message, and only MAIL FROM, RCPT TO, and DATA are
2074 relevant. After an error on a sender, or an invalid recipient, the remainder
2075 of the message is skipped. The value of received_protocol is already set.
2076
2077 Argument: none
2078 Returns: > 0 message successfully started (reached DATA)
2079 = 0 QUIT read or end of file reached
2080 < 0 should not occur
2081 */
2082
2083 static int
2084 smtp_setup_batch_msg(void)
2085 {
2086 int done = 0;
2087 void *reset_point = store_get(0);
2088
2089 /* Save the line count at the start of each transaction - single commands
2090 like HELO and RSET count as whole transactions. */
2091
2092 bsmtp_transaction_linecount = receive_linecount;
2093
2094 if ((receive_feof)()) return 0; /* Treat EOF as QUIT */
2095
2096 cancel_cutthrough_connection(TRUE, US"smtp_setup_batch_msg");
2097 smtp_reset(reset_point); /* Reset for start of message */
2098
2099 /* Deal with SMTP commands. This loop is exited by setting done to a POSITIVE
2100 value. The values are 2 larger than the required yield of the function. */
2101
2102 while (done <= 0)
2103 {
2104 uschar *errmess;
2105 uschar *recipient = NULL;
2106 int start, end, sender_domain, recipient_domain;
2107
2108 switch(smtp_read_command(FALSE, GETC_BUFFER_UNLIMITED))
2109 {
2110 /* The HELO/EHLO commands set sender_address_helo if they have
2111 valid data; otherwise they are ignored, except that they do
2112 a reset of the state. */
2113
2114 case HELO_CMD:
2115 case EHLO_CMD:
2116
2117 check_helo(smtp_cmd_data);
2118 /* Fall through */
2119
2120 case RSET_CMD:
2121 cancel_cutthrough_connection(TRUE, US"RSET received");
2122 smtp_reset(reset_point);
2123 bsmtp_transaction_linecount = receive_linecount;
2124 break;
2125
2126
2127 /* The MAIL FROM command requires an address as an operand. All we
2128 do here is to parse it for syntactic correctness. The form "<>" is
2129 a special case which converts into an empty string. The start/end
2130 pointers in the original are not used further for this address, as
2131 it is the canonical extracted address which is all that is kept. */
2132
2133 case MAIL_CMD:
2134 smtp_mailcmd_count++; /* Count for no-mail log */
2135 if (sender_address != NULL)
2136 /* The function moan_smtp_batch() does not return. */
2137 moan_smtp_batch(smtp_cmd_buffer, "503 Sender already given");
2138
2139 if (smtp_cmd_data[0] == 0)
2140 /* The function moan_smtp_batch() does not return. */
2141 moan_smtp_batch(smtp_cmd_buffer, "501 MAIL FROM must have an address operand");
2142
2143 /* Reset to start of message */
2144
2145 cancel_cutthrough_connection(TRUE, US"MAIL received");
2146 smtp_reset(reset_point);
2147
2148 /* Apply SMTP rewrite */
2149
2150 raw_sender = ((rewrite_existflags & rewrite_smtp) != 0)?
2151 rewrite_one(smtp_cmd_data, rewrite_smtp|rewrite_smtp_sender, NULL, FALSE,
2152 US"", global_rewrite_rules) : smtp_cmd_data;
2153
2154 /* Extract the address; the TRUE flag allows <> as valid */
2155
2156 raw_sender =
2157 parse_extract_address(raw_sender, &errmess, &start, &end, &sender_domain,
2158 TRUE);
2159
2160 if (!raw_sender)
2161 /* The function moan_smtp_batch() does not return. */
2162 moan_smtp_batch(smtp_cmd_buffer, "501 %s", errmess);
2163
2164 sender_address = string_copy(raw_sender);
2165
2166 /* Qualify unqualified sender addresses if permitted to do so. */
2167
2168 if ( !sender_domain
2169 && sender_address[0] != 0 && sender_address[0] != '@')
2170 if (allow_unqualified_sender)
2171 {
2172 sender_address = rewrite_address_qualify(sender_address, FALSE);
2173 DEBUG(D_receive) debug_printf("unqualified address %s accepted "
2174 "and rewritten\n", raw_sender);
2175 }
2176 /* The function moan_smtp_batch() does not return. */
2177 else
2178 moan_smtp_batch(smtp_cmd_buffer, "501 sender address must contain "
2179 "a domain");
2180 break;
2181
2182
2183 /* The RCPT TO command requires an address as an operand. All we do
2184 here is to parse it for syntactic correctness. There may be any number
2185 of RCPT TO commands, specifying multiple senders. We build them all into
2186 a data structure that is in argc/argv format. The start/end values
2187 given by parse_extract_address are not used, as we keep only the
2188 extracted address. */
2189
2190 case RCPT_CMD:
2191 if (!sender_address)
2192 /* The function moan_smtp_batch() does not return. */
2193 moan_smtp_batch(smtp_cmd_buffer, "503 No sender yet given");
2194
2195 if (smtp_cmd_data[0] == 0)
2196 /* The function moan_smtp_batch() does not return. */
2197 moan_smtp_batch(smtp_cmd_buffer,
2198 "501 RCPT TO must have an address operand");
2199
2200 /* Check maximum number allowed */
2201
2202 if (recipients_max > 0 && recipients_count + 1 > recipients_max)
2203 /* The function moan_smtp_batch() does not return. */
2204 moan_smtp_batch(smtp_cmd_buffer, "%s too many recipients",
2205 recipients_max_reject? "552": "452");
2206
2207 /* Apply SMTP rewrite, then extract address. Don't allow "<>" as a
2208 recipient address */
2209
2210 recipient = rewrite_existflags & rewrite_smtp
2211 ? rewrite_one(smtp_cmd_data, rewrite_smtp, NULL, FALSE, US"",
2212 global_rewrite_rules)
2213 : smtp_cmd_data;
2214
2215 recipient = parse_extract_address(recipient, &errmess, &start, &end,
2216 &recipient_domain, FALSE);
2217
2218 if (!recipient)
2219 /* The function moan_smtp_batch() does not return. */
2220 moan_smtp_batch(smtp_cmd_buffer, "501 %s", errmess);
2221
2222 /* If the recipient address is unqualified, qualify it if permitted. Then
2223 add it to the list of recipients. */
2224
2225 if (!recipient_domain)
2226 if (allow_unqualified_recipient)
2227 {
2228 DEBUG(D_receive) debug_printf("unqualified address %s accepted\n",
2229 recipient);
2230 recipient = rewrite_address_qualify(recipient, TRUE);
2231 }
2232 /* The function moan_smtp_batch() does not return. */
2233 else
2234 moan_smtp_batch(smtp_cmd_buffer,
2235 "501 recipient address must contain a domain");
2236
2237 receive_add_recipient(recipient, -1);
2238 break;
2239
2240
2241 /* The DATA command is legal only if it follows successful MAIL FROM
2242 and RCPT TO commands. This function is complete when a valid DATA
2243 command is encountered. */
2244
2245 case DATA_CMD:
2246 if (!sender_address || recipients_count <= 0)
2247 /* The function moan_smtp_batch() does not return. */
2248 if (!sender_address)
2249 moan_smtp_batch(smtp_cmd_buffer,
2250 "503 MAIL FROM:<sender> command must precede DATA");
2251 else
2252 moan_smtp_batch(smtp_cmd_buffer,
2253 "503 RCPT TO:<recipient> must precede DATA");
2254 else
2255 {
2256 done = 3; /* DATA successfully achieved */
2257 message_ended = END_NOTENDED; /* Indicate in middle of message */
2258 }
2259 break;
2260
2261
2262 /* The VRFY, EXPN, HELP, ETRN, and NOOP commands are ignored. */
2263
2264 case VRFY_CMD:
2265 case EXPN_CMD:
2266 case HELP_CMD:
2267 case NOOP_CMD:
2268 case ETRN_CMD:
2269 bsmtp_transaction_linecount = receive_linecount;
2270 break;
2271
2272
2273 case EOF_CMD:
2274 case QUIT_CMD:
2275 done = 2;
2276 break;
2277
2278
2279 case BADARG_CMD:
2280 /* The function moan_smtp_batch() does not return. */
2281 moan_smtp_batch(smtp_cmd_buffer, "501 Unexpected argument data");
2282 break;
2283
2284
2285 case BADCHAR_CMD:
2286 /* The function moan_smtp_batch() does not return. */
2287 moan_smtp_batch(smtp_cmd_buffer, "501 Unexpected NULL in SMTP command");
2288 break;
2289
2290
2291 default:
2292 /* The function moan_smtp_batch() does not return. */
2293 moan_smtp_batch(smtp_cmd_buffer, "500 Command unrecognized");
2294 break;
2295 }
2296 }
2297
2298 return done - 2; /* Convert yield values */
2299 }
2300
2301
2302
2303
2304 static BOOL
2305 smtp_log_tls_fail(uschar * errstr)
2306 {
2307 uschar * conn_info = smtp_get_connection_info();
2308
2309 if (Ustrncmp(conn_info, US"SMTP ", 5) == 0) conn_info += 5;
2310 /* I'd like to get separated H= here, but too hard for now */
2311
2312 log_write(0, LOG_MAIN, "TLS error on %s %s", conn_info, errstr);
2313 return FALSE;
2314 }
2315
2316
2317
2318
2319 #ifdef TCP_FASTOPEN
2320 static void
2321 tfo_in_check(void)
2322 {
2323 # ifdef TCP_INFO
2324 struct tcp_info tinfo;
2325 socklen_t len = sizeof(tinfo);
2326
2327 if ( getsockopt(fileno(smtp_out), IPPROTO_TCP, TCP_INFO, &tinfo, &len) == 0
2328 && tinfo.tcpi_state == TCP_SYN_RECV
2329 )
2330 {
2331 DEBUG(D_receive) debug_printf("TCP_FASTOPEN mode connection (state TCP_SYN_RECV)\n");
2332 tcp_in_fastopen = TRUE;
2333 }
2334 # endif
2335 }
2336 #endif
2337
2338
2339 /*************************************************
2340 * Start an SMTP session *
2341 *************************************************/
2342
2343 /* This function is called at the start of an SMTP session. Thereafter,
2344 smtp_setup_msg() is called to initiate each separate message. This
2345 function does host-specific testing, and outputs the banner line.
2346
2347 Arguments: none
2348 Returns: FALSE if the session can not continue; something has
2349 gone wrong, or the connection to the host is blocked
2350 */
2351
2352 BOOL
2353 smtp_start_session(void)
2354 {
2355 int esclen;
2356 uschar *user_msg, *log_msg;
2357 uschar *code, *esc;
2358 uschar *p, *s;
2359 gstring * ss;
2360
2361 gettimeofday(&smtp_connection_start, NULL);
2362 for (smtp_ch_index = 0; smtp_ch_index < SMTP_HBUFF_SIZE; smtp_ch_index++)
2363 smtp_connection_had[smtp_ch_index] = SCH_NONE;
2364 smtp_ch_index = 0;
2365
2366 /* Default values for certain variables */
2367
2368 helo_seen = esmtp = helo_accept_junk = FALSE;
2369 smtp_mailcmd_count = 0;
2370 count_nonmail = TRUE_UNSET;
2371 synprot_error_count = unknown_command_count = nonmail_command_count = 0;
2372 smtp_delay_mail = smtp_rlm_base;
2373 auth_advertised = FALSE;
2374 pipelining_advertised = FALSE;
2375 pipelining_enable = TRUE;
2376 sync_cmd_limit = NON_SYNC_CMD_NON_PIPELINING;
2377 smtp_exit_function_called = FALSE; /* For avoiding loop in not-quit exit */
2378
2379 /* If receiving by -bs from a trusted user, or testing with -bh, we allow
2380 authentication settings from -oMaa to remain in force. */
2381
2382 if (!host_checking && !sender_host_notsocket)
2383 sender_host_auth_pubname = sender_host_authenticated = NULL;
2384 authenticated_by = NULL;
2385
2386 #ifdef SUPPORT_TLS
2387 tls_in.cipher = tls_in.peerdn = NULL;
2388 tls_in.ourcert = tls_in.peercert = NULL;
2389 tls_in.sni = NULL;
2390 tls_in.ocsp = OCSP_NOT_REQ;
2391 tls_advertised = FALSE;
2392 #endif
2393 dsn_advertised = FALSE;
2394 #ifdef SUPPORT_I18N
2395 smtputf8_advertised = FALSE;
2396 #endif
2397
2398 /* Reset ACL connection variables */
2399
2400 acl_var_c = NULL;
2401
2402 /* Allow for trailing 0 in the command and data buffers. */
2403
2404 if (!(smtp_cmd_buffer = US malloc(2*SMTP_CMD_BUFFER_SIZE + 2)))
2405 log_write(0, LOG_MAIN|LOG_PANIC_DIE,
2406 "malloc() failed for SMTP command buffer");
2407
2408 smtp_cmd_buffer[0] = 0;
2409 smtp_data_buffer = smtp_cmd_buffer + SMTP_CMD_BUFFER_SIZE + 1;
2410
2411 /* For batched input, the protocol setting can be overridden from the
2412 command line by a trusted caller. */
2413
2414 if (smtp_batched_input)
2415 {
2416 if (!received_protocol) received_protocol = US"local-bsmtp";
2417 }
2418
2419 /* For non-batched SMTP input, the protocol setting is forced here. It will be
2420 reset later if any of EHLO/AUTH/STARTTLS are received. */
2421
2422 else
2423 received_protocol =
2424 (sender_host_address ? protocols : protocols_local) [pnormal];
2425
2426 /* Set up the buffer for inputting using direct read() calls, and arrange to
2427 call the local functions instead of the standard C ones. Place a NUL at the
2428 end of the buffer to safety-stop C-string reads from it. */
2429
2430 if (!(smtp_inbuffer = US malloc(IN_BUFFER_SIZE)))
2431 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "malloc() failed for SMTP input buffer");
2432 smtp_inbuffer[IN_BUFFER_SIZE-1] = '\0';
2433
2434 receive_getc = smtp_getc;
2435 receive_getbuf = smtp_getbuf;
2436 receive_get_cache = smtp_get_cache;
2437 receive_ungetc = smtp_ungetc;
2438 receive_feof = smtp_feof;
2439 receive_ferror = smtp_ferror;
2440 receive_smtp_buffered = smtp_buffered;
2441 smtp_inptr = smtp_inend = smtp_inbuffer;
2442 smtp_had_eof = smtp_had_error = 0;
2443
2444 /* Set up the message size limit; this may be host-specific */
2445
2446 thismessage_size_limit = expand_string_integer(message_size_limit, TRUE);
2447 if (expand_string_message)
2448 {
2449 if (thismessage_size_limit == -1)
2450 log_write(0, LOG_MAIN|LOG_PANIC, "unable to expand message_size_limit: "
2451 "%s", expand_string_message);
2452 else
2453 log_write(0, LOG_MAIN|LOG_PANIC, "invalid message_size_limit: "
2454 "%s", expand_string_message);
2455 smtp_closedown(US"Temporary local problem - please try later");
2456 return FALSE;
2457 }
2458
2459 /* When a message is input locally via the -bs or -bS options, sender_host_
2460 unknown is set unless -oMa was used to force an IP address, in which case it
2461 is checked like a real remote connection. When -bs is used from inetd, this
2462 flag is not set, causing the sending host to be checked. The code that deals
2463 with IP source routing (if configured) is never required for -bs or -bS and
2464 the flag sender_host_notsocket is used to suppress it.
2465
2466 If smtp_accept_max and smtp_accept_reserve are set, keep some connections in
2467 reserve for certain hosts and/or networks. */
2468
2469 if (!sender_host_unknown)
2470 {
2471 int rc;
2472 BOOL reserved_host = FALSE;
2473
2474 /* Look up IP options (source routing info) on the socket if this is not an
2475 -oMa "host", and if any are found, log them and drop the connection.
2476
2477 Linux (and others now, see below) is different to everyone else, so there
2478 has to be some conditional compilation here. Versions of Linux before 2.1.15
2479 used a structure whose name was "options". Somebody finally realized that
2480 this name was silly, and it got changed to "ip_options". I use the
2481 newer name here, but there is a fudge in the script that sets up os.h
2482 to define a macro in older Linux systems.
2483
2484 Sigh. Linux is a fast-moving target. Another generation of Linux uses
2485 glibc 2, which has chosen ip_opts for the structure name. This is now
2486 really a glibc thing rather than a Linux thing, so the condition name
2487 has been changed to reflect this. It is relevant also to GNU/Hurd.
2488
2489 Mac OS 10.x (Darwin) is like the later glibc versions, but without the
2490 setting of the __GLIBC__ macro, so we can't detect it automatically. There's
2491 a special macro defined in the os.h file.
2492
2493 Some DGUX versions on older hardware appear not to support IP options at
2494 all, so there is now a general macro which can be set to cut out this
2495 support altogether.
2496
2497 How to do this properly in IPv6 is not yet known. */
2498
2499 #if !HAVE_IPV6 && !defined(NO_IP_OPTIONS)
2500
2501 #ifdef GLIBC_IP_OPTIONS
2502 #if (!defined __GLIBC__) || (__GLIBC__ < 2)
2503 #define OPTSTYLE 1
2504 #else
2505 #define OPTSTYLE 2
2506 #endif
2507 #elif defined DARWIN_IP_OPTIONS
2508 #define OPTSTYLE 2
2509 #else
2510 #define OPTSTYLE 3
2511 #endif
2512
2513 if (!host_checking && !sender_host_notsocket)
2514 {
2515 #if OPTSTYLE == 1
2516 EXIM_SOCKLEN_T optlen = sizeof(struct ip_options) + MAX_IPOPTLEN;
2517 struct ip_options *ipopt = store_get(optlen);
2518 #elif OPTSTYLE == 2
2519 struct ip_opts ipoptblock;
2520 struct ip_opts *ipopt = &ipoptblock;
2521 EXIM_SOCKLEN_T optlen = sizeof(ipoptblock);
2522 #else
2523 struct ipoption ipoptblock;
2524 struct ipoption *ipopt = &ipoptblock;
2525 EXIM_SOCKLEN_T optlen = sizeof(ipoptblock);
2526 #endif
2527
2528 /* Occasional genuine failures of getsockopt() have been seen - for
2529 example, "reset by peer". Therefore, just log and give up on this
2530 call, unless the error is ENOPROTOOPT. This error is given by systems
2531 that have the interfaces but not the mechanism - e.g. GNU/Hurd at the time
2532 of writing. So for that error, carry on - we just can't do an IP options
2533 check. */
2534
2535 DEBUG(D_receive) debug_printf("checking for IP options\n");
2536
2537 if (getsockopt(fileno(smtp_out), IPPROTO_IP, IP_OPTIONS, US (ipopt),
2538 &optlen) < 0)
2539 {
2540 if (errno != ENOPROTOOPT)
2541 {
2542 log_write(0, LOG_MAIN, "getsockopt() failed from %s: %s",
2543 host_and_ident(FALSE), strerror(errno));
2544 smtp_printf("451 SMTP service not available\r\n", FALSE);
2545 return FALSE;
2546 }
2547 }
2548
2549 /* Deal with any IP options that are set. On the systems I have looked at,
2550 the value of MAX_IPOPTLEN has been 40, meaning that there should never be
2551 more logging data than will fit in big_buffer. Nevertheless, after somebody
2552 questioned this code, I've added in some paranoid checking. */
2553
2554 else if (optlen > 0)
2555 {
2556 uschar *p = big_buffer;
2557 uschar *pend = big_buffer + big_buffer_size;
2558 uschar *opt, *adptr;
2559 int optcount;
2560 struct in_addr addr;
2561
2562 #if OPTSTYLE == 1
2563 uschar *optstart = US (ipopt->__data);
2564 #elif OPTSTYLE == 2
2565 uschar *optstart = US (ipopt->ip_opts);
2566 #else
2567 uschar *optstart = US (ipopt->ipopt_list);
2568 #endif
2569
2570 DEBUG(D_receive) debug_printf("IP options exist\n");
2571
2572 Ustrcpy(p, "IP options on incoming call:");
2573 p += Ustrlen(p);
2574
2575 for (opt = optstart; opt != NULL &&
2576 opt < US (ipopt) + optlen;)
2577 {
2578 switch (*opt)
2579 {
2580 case IPOPT_EOL:
2581 opt = NULL;
2582 break;
2583
2584 case IPOPT_NOP:
2585 opt++;
2586 break;
2587
2588 case IPOPT_SSRR:
2589 case IPOPT_LSRR:
2590 if (!string_format(p, pend-p, " %s [@%s",
2591 (*opt == IPOPT_SSRR)? "SSRR" : "LSRR",
2592 #if OPTSTYLE == 1
2593 inet_ntoa(*((struct in_addr *)(&(ipopt->faddr))))))
2594 #elif OPTSTYLE == 2
2595 inet_ntoa(ipopt->ip_dst)))
2596 #else
2597 inet_ntoa(ipopt->ipopt_dst)))
2598 #endif
2599 {
2600 opt = NULL;
2601 break;
2602 }
2603
2604 p += Ustrlen(p);
2605 optcount = (opt[1] - 3) / sizeof(struct in_addr);
2606 adptr = opt + 3;
2607 while (optcount-- > 0)
2608 {
2609 memcpy(&addr, adptr, sizeof(addr));
2610 if (!string_format(p, pend - p - 1, "%s%s",
2611 (optcount == 0)? ":" : "@", inet_ntoa(addr)))
2612 {
2613 opt = NULL;
2614 break;
2615 }
2616 p += Ustrlen(p);
2617 adptr += sizeof(struct in_addr);
2618 }
2619 *p++ = ']';
2620 opt += opt[1];
2621 break;
2622
2623 default:
2624 {
2625 int i;
2626 if (pend - p < 4 + 3*opt[1]) { opt = NULL; break; }
2627 Ustrcat(p, "[ ");
2628 p += 2;
2629 for (i = 0; i < opt[1]; i++)
2630 p += sprintf(CS p, "%2.2x ", opt[i]);
2631 *p++ = ']';
2632 }
2633 opt += opt[1];
2634 break;
2635 }
2636 }
2637
2638 *p = 0;
2639 log_write(0, LOG_MAIN, "%s", big_buffer);
2640
2641 /* Refuse any call with IP options. This is what tcpwrappers 7.5 does. */
2642
2643 log_write(0, LOG_MAIN|LOG_REJECT,
2644 "connection from %s refused (IP options)", host_and_ident(FALSE));
2645
2646 smtp_printf("554 SMTP service not available\r\n", FALSE);
2647 return FALSE;
2648 }
2649
2650 /* Length of options = 0 => there are no options */
2651
2652 else DEBUG(D_receive) debug_printf("no IP options found\n");
2653 }
2654 #endif /* HAVE_IPV6 && !defined(NO_IP_OPTIONS) */
2655
2656 /* Set keep-alive in socket options. The option is on by default. This
2657 setting is an attempt to get rid of some hanging connections that stick in
2658 read() when the remote end (usually a dialup) goes away. */
2659
2660 if (smtp_accept_keepalive && !sender_host_notsocket)
2661 ip_keepalive(fileno(smtp_out), sender_host_address, FALSE);
2662
2663 /* If the current host matches host_lookup, set the name by doing a
2664 reverse lookup. On failure, sender_host_name will be NULL and
2665 host_lookup_failed will be TRUE. This may or may not be serious - optional
2666 checks later. */
2667
2668 if (verify_check_host(&host_lookup) == OK)
2669 {
2670 (void)host_name_lookup();
2671 host_build_sender_fullhost();
2672 }
2673
2674 /* Delay this until we have the full name, if it is looked up. */
2675
2676 set_process_info("handling incoming connection from %s",
2677 host_and_ident(FALSE));
2678
2679 /* Expand smtp_receive_timeout, if needed */
2680
2681 if (smtp_receive_timeout_s)
2682 {
2683 uschar * exp;
2684 if ( !(exp = expand_string(smtp_receive_timeout_s))
2685 || !(*exp)
2686 || (smtp_receive_timeout = readconf_readtime(exp, 0, FALSE)) < 0
2687 )
2688 log_write(0, LOG_MAIN|LOG_PANIC,
2689 "bad value for smtp_receive_timeout: '%s'", exp ? exp : US"");
2690 }
2691
2692 /* Test for explicit connection rejection */
2693
2694 if (verify_check_host(&host_reject_connection) == OK)
2695 {
2696 log_write(L_connection_reject, LOG_MAIN|LOG_REJECT, "refused connection "
2697 "from %s (host_reject_connection)", host_and_ident(FALSE));
2698 smtp_printf("554 SMTP service not available\r\n", FALSE);
2699 return FALSE;
2700 }
2701
2702 /* Test with TCP Wrappers if so configured. There is a problem in that
2703 hosts_ctl() returns 0 (deny) under a number of system failure circumstances,
2704 such as disks dying. In these cases, it is desirable to reject with a 4xx
2705 error instead of a 5xx error. There isn't a "right" way to detect such
2706 problems. The following kludge is used: errno is zeroed before calling
2707 hosts_ctl(). If the result is "reject", a 5xx error is given only if the
2708 value of errno is 0 or ENOENT (which happens if /etc/hosts.{allow,deny} does
2709 not exist). */
2710
2711 #ifdef USE_TCP_WRAPPERS
2712 errno = 0;
2713 if (!(tcp_wrappers_name = expand_string(tcp_wrappers_daemon_name)))
2714 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "Expansion of \"%s\" "
2715 "(tcp_wrappers_name) failed: %s", string_printing(tcp_wrappers_name),
2716 expand_string_message);
2717
2718 if (!hosts_ctl(tcp_wrappers_name,
2719 sender_host_name ? CS sender_host_name : STRING_UNKNOWN,
2720 sender_host_address ? CS sender_host_address : STRING_UNKNOWN,
2721 sender_ident ? CS sender_ident : STRING_UNKNOWN))
2722 {
2723 if (errno == 0 || errno == ENOENT)
2724 {
2725 HDEBUG(D_receive) debug_printf("tcp wrappers rejection\n");
2726 log_write(L_connection_reject,
2727 LOG_MAIN|LOG_REJECT, "refused connection from %s "
2728 "(tcp wrappers)", host_and_ident(FALSE));
2729 smtp_printf("554 SMTP service not available\r\n", FALSE);
2730 }
2731 else
2732 {
2733 int save_errno = errno;
2734 HDEBUG(D_receive) debug_printf("tcp wrappers rejected with unexpected "
2735 "errno value %d\n", save_errno);
2736 log_write(L_connection_reject,
2737 LOG_MAIN|LOG_REJECT, "temporarily refused connection from %s "
2738 "(tcp wrappers errno=%d)", host_and_ident(FALSE), save_errno);
2739 smtp_printf("451 Temporary local problem - please try later\r\n", FALSE);
2740 }
2741 return FALSE;
2742 }
2743 #endif
2744
2745 /* Check for reserved slots. The value of smtp_accept_count has already been
2746 incremented to include this process. */
2747
2748 if (smtp_accept_max > 0 &&
2749 smtp_accept_count > smtp_accept_max - smtp_accept_reserve)
2750 {
2751 if ((rc = verify_check_host(&smtp_reserve_hosts)) != OK)
2752 {
2753 log_write(L_connection_reject,
2754 LOG_MAIN, "temporarily refused connection from %s: not in "
2755 "reserve list: connected=%d max=%d reserve=%d%s",
2756 host_and_ident(FALSE), smtp_accept_count - 1, smtp_accept_max,
2757 smtp_accept_reserve, (rc == DEFER)? " (lookup deferred)" : "");
2758 smtp_printf("421 %s: Too many concurrent SMTP connections; "
2759 "please try again later\r\n", FALSE, smtp_active_hostname);
2760 return FALSE;
2761 }
2762 reserved_host = TRUE;
2763 }
2764
2765 /* If a load level above which only messages from reserved hosts are
2766 accepted is set, check the load. For incoming calls via the daemon, the
2767 check is done in the superior process if there are no reserved hosts, to
2768 save a fork. In all cases, the load average will already be available
2769 in a global variable at this point. */
2770
2771 if (smtp_load_reserve >= 0 &&
2772 load_average > smtp_load_reserve &&
2773 !reserved_host &&
2774 verify_check_host(&smtp_reserve_hosts) != OK)
2775 {
2776 log_write(L_connection_reject,
2777 LOG_MAIN, "temporarily refused connection from %s: not in "
2778 "reserve list and load average = %.2f", host_and_ident(FALSE),
2779 (double)load_average/1000.0);
2780 smtp_printf("421 %s: Too much load; please try again later\r\n", FALSE,
2781 smtp_active_hostname);
2782 return FALSE;
2783 }
2784
2785 /* Determine whether unqualified senders or recipients are permitted
2786 for this host. Unfortunately, we have to do this every time, in order to
2787 set the flags so that they can be inspected when considering qualifying
2788 addresses in the headers. For a site that permits no qualification, this
2789 won't take long, however. */
2790
2791 allow_unqualified_sender =
2792 verify_check_host(&sender_unqualified_hosts) == OK;
2793
2794 allow_unqualified_recipient =
2795 verify_check_host(&recipient_unqualified_hosts) == OK;
2796
2797 /* Determine whether HELO/EHLO is required for this host. The requirement
2798 can be hard or soft. */
2799
2800 helo_required = verify_check_host(&helo_verify_hosts) == OK;
2801 if (!helo_required)
2802 helo_verify = verify_check_host(&helo_try_verify_hosts) == OK;
2803
2804 /* Determine whether this hosts is permitted to send syntactic junk
2805 after a HELO or EHLO command. */
2806
2807 helo_accept_junk = verify_check_host(&helo_accept_junk_hosts) == OK;
2808 }
2809
2810 /* For batch SMTP input we are now done. */
2811
2812 if (smtp_batched_input) return TRUE;
2813
2814 /* If valid Proxy Protocol source is connecting, set up session.
2815 * Failure will not allow any SMTP function other than QUIT. */
2816
2817 #ifdef SUPPORT_PROXY
2818 proxy_session = FALSE;
2819 proxy_session_failed = FALSE;
2820 if (check_proxy_protocol_host())
2821 setup_proxy_protocol_host();
2822 #endif
2823
2824 /* Start up TLS if tls_on_connect is set. This is for supporting the legacy
2825 smtps port for use with older style SSL MTAs. */
2826
2827 #ifdef SUPPORT_TLS
2828 if (tls_in.on_connect)
2829 {
2830 if (tls_server_start(tls_require_ciphers, &user_msg) != OK)
2831 return smtp_log_tls_fail(user_msg);
2832 cmd_list[CMD_LIST_TLS_AUTH].is_mail_cmd = TRUE;
2833 }
2834 #endif
2835
2836 /* Run the connect ACL if it exists */
2837
2838 user_msg = NULL;
2839 if (acl_smtp_connect)
2840 {
2841 int rc;
2842 if ((rc = acl_check(ACL_WHERE_CONNECT, NULL, acl_smtp_connect, &user_msg,
2843 &log_msg)) != OK)
2844 {
2845 (void) smtp_handle_acl_fail(ACL_WHERE_CONNECT, rc, user_msg, log_msg);
2846 return FALSE;
2847 }
2848 }
2849
2850 /* Output the initial message for a two-way SMTP connection. It may contain
2851 newlines, which then cause a multi-line response to be given. */
2852
2853 code = US"220"; /* Default status code */
2854 esc = US""; /* Default extended status code */
2855 esclen = 0; /* Length of esc */
2856
2857 if (!user_msg)
2858 {
2859 if (!(s = expand_string(smtp_banner)))
2860 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "Expansion of \"%s\" (smtp_banner) "
2861 "failed: %s", smtp_banner, expand_string_message);
2862 }
2863 else
2864 {
2865 int codelen = 3;
2866 s = user_msg;
2867 smtp_message_code(&code, &codelen, &s, NULL, TRUE);
2868 if (codelen > 4)
2869 {
2870 esc = code + 4;
2871 esclen = codelen - 4;
2872 }
2873 }
2874
2875 /* Remove any terminating newlines; might as well remove trailing space too */
2876
2877 p = s + Ustrlen(s);
2878 while (p > s && isspace(p[-1])) p--;
2879 *p = 0;
2880
2881 /* It seems that CC:Mail is braindead, and assumes that the greeting message
2882 is all contained in a single IP packet. The original code wrote out the
2883 greeting using several calls to fprint/fputc, and on busy servers this could
2884 cause it to be split over more than one packet - which caused CC:Mail to fall
2885 over when it got the second part of the greeting after sending its first
2886 command. Sigh. To try to avoid this, build the complete greeting message
2887 first, and output it in one fell swoop. This gives a better chance of it
2888 ending up as a single packet. */
2889
2890 ss = string_get(256);
2891
2892 p = s;
2893 do /* At least once, in case we have an empty string */
2894 {
2895 int len;
2896 uschar *linebreak = Ustrchr(p, '\n');
2897 ss = string_catn(ss, code, 3);
2898 if (!linebreak)
2899 {
2900 len = Ustrlen(p);
2901 ss = string_catn(ss, US" ", 1);
2902 }
2903 else
2904 {
2905 len = linebreak - p;
2906 ss = string_catn(ss, US"-", 1);
2907 }
2908 ss = string_catn(ss, esc, esclen);
2909 ss = string_catn(ss, p, len);
2910 ss = string_catn(ss, US"\r\n", 2);
2911 p += len;
2912 if (linebreak) p++;
2913 }
2914 while (*p);
2915
2916 /* Before we write the banner, check that there is no input pending, unless
2917 this synchronisation check is disabled. */
2918
2919 if (!check_sync())
2920 {
2921 unsigned n = smtp_inend - smtp_inptr;
2922 if (n > 32) n = 32;
2923
2924 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP protocol "
2925 "synchronization error (input sent without waiting for greeting): "
2926 "rejected connection from %s input=\"%s\"", host_and_ident(TRUE),
2927 string_printing(string_copyn(smtp_inptr, n)));
2928 smtp_printf("554 SMTP synchronization error\r\n", FALSE);
2929 return FALSE;
2930 }
2931
2932 /* Now output the banner */
2933
2934 smtp_printf("%s", FALSE, string_from_gstring(ss));
2935
2936 /* Attempt to see if we sent the banner before the last ACK of the 3-way
2937 handshake arrived. If so we must have managed a TFO. */
2938
2939 #ifdef TCP_FASTOPEN
2940 tfo_in_check();
2941 #endif
2942
2943 return TRUE;
2944 }
2945
2946
2947
2948
2949
2950 /*************************************************
2951 * Handle SMTP syntax and protocol errors *
2952 *************************************************/
2953
2954 /* Write to the log for SMTP syntax errors in incoming commands, if configured
2955 to do so. Then transmit the error response. The return value depends on the
2956 number of syntax and protocol errors in this SMTP session.
2957
2958 Arguments:
2959 type error type, given as a log flag bit
2960 code response code; <= 0 means don't send a response
2961 data data to reflect in the response (can be NULL)
2962 errmess the error message
2963
2964 Returns: -1 limit of syntax/protocol errors NOT exceeded
2965 +1 limit of syntax/protocol errors IS exceeded
2966
2967 These values fit in with the values of the "done" variable in the main
2968 processing loop in smtp_setup_msg(). */
2969
2970 static int
2971 synprot_error(int type, int code, uschar *data, uschar *errmess)
2972 {
2973 int yield = -1;
2974
2975 log_write(type, LOG_MAIN, "SMTP %s error in \"%s\" %s %s",
2976 (type == L_smtp_syntax_error)? "syntax" : "protocol",
2977 string_printing(smtp_cmd_buffer), host_and_ident(TRUE), errmess);
2978
2979 if (++synprot_error_count > smtp_max_synprot_errors)
2980 {
2981 yield = 1;
2982 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
2983 "syntax or protocol errors (last command was \"%s\")",
2984 host_and_ident(FALSE), string_printing(smtp_cmd_buffer));
2985 }
2986
2987 if (code > 0)
2988 {
2989 smtp_printf("%d%c%s%s%s\r\n", FALSE, code, yield == 1 ? '-' : ' ',
2990 data ? data : US"", data ? US": " : US"", errmess);
2991 if (yield == 1)
2992 smtp_printf("%d Too many syntax or protocol errors\r\n", FALSE, code);
2993 }
2994
2995 return yield;
2996 }
2997
2998
2999
3000
3001 /*************************************************
3002 * Send SMTP response, possibly multiline *
3003 *************************************************/
3004
3005 /* There are, it seems, broken clients out there that cannot handle multiline
3006 responses. If no_multiline_responses is TRUE (it can be set from an ACL), we
3007 output nothing for non-final calls, and only the first line for anything else.
3008
3009 Arguments:
3010 code SMTP code, may involve extended status codes
3011 codelen length of smtp code; if > 4 there's an ESC
3012 final FALSE if the last line isn't the final line
3013 msg message text, possibly containing newlines
3014
3015 Returns: nothing
3016 */
3017
3018 void
3019 smtp_respond(uschar* code, int codelen, BOOL final, uschar *msg)
3020 {
3021 int esclen = 0;
3022 uschar *esc = US"";
3023
3024 if (!final && no_multiline_responses) return;
3025
3026 if (codelen > 4)
3027 {
3028 esc = code + 4;
3029 esclen = codelen - 4;
3030 }
3031
3032 /* If this is the first output for a (non-batch) RCPT command, see if all RCPTs
3033 have had the same. Note: this code is also present in smtp_printf(). It would
3034 be tidier to have it only in one place, but when it was added, it was easier to
3035 do it that way, so as not to have to mess with the code for the RCPT command,
3036 which sometimes uses smtp_printf() and sometimes smtp_respond(). */
3037
3038 if (rcpt_in_progress)
3039 {
3040 if (rcpt_smtp_response == NULL)
3041 rcpt_smtp_response = string_copy(msg);
3042 else if (rcpt_smtp_response_same &&
3043 Ustrcmp(rcpt_smtp_response, msg) != 0)
3044 rcpt_smtp_response_same = FALSE;
3045 rcpt_in_progress = FALSE;
3046 }
3047
3048 /* Now output the message, splitting it up into multiple lines if necessary.
3049 We only handle pipelining these responses as far as nonfinal/final groups,
3050 not the whole MAIL/RCPT/DATA response set. */
3051
3052 for (;;)
3053 {
3054 uschar *nl = Ustrchr(msg, '\n');
3055 if (nl == NULL)
3056 {
3057 smtp_printf("%.3s%c%.*s%s\r\n", !final, code, final ? ' ':'-', esclen, esc, msg);
3058 return;
3059 }
3060 else if (nl[1] == 0 || no_multiline_responses)
3061 {
3062 smtp_printf("%.3s%c%.*s%.*s\r\n", !final, code, final ? ' ':'-', esclen, esc,
3063 (int)(nl - msg), msg);
3064 return;
3065 }
3066 else
3067 {
3068 smtp_printf("%.3s-%.*s%.*s\r\n", TRUE, code, esclen, esc, (int)(nl - msg), msg);
3069 msg = nl + 1;
3070 while (isspace(*msg)) msg++;
3071 }
3072 }
3073 }
3074
3075
3076
3077
3078 /*************************************************
3079 * Parse user SMTP message *
3080 *************************************************/
3081
3082 /* This function allows for user messages overriding the response code details
3083 by providing a suitable response code string at the start of the message
3084 user_msg. Check the message for starting with a response code and optionally an
3085 extended status code. If found, check that the first digit is valid, and if so,
3086 change the code pointer and length to use the replacement. An invalid code
3087 causes a panic log; in this case, if the log messages is the same as the user
3088 message, we must also adjust the value of the log message to show the code that
3089 is actually going to be used (the original one).
3090
3091 This function is global because it is called from receive.c as well as within
3092 this module.
3093
3094 Note that the code length returned includes the terminating whitespace
3095 character, which is always included in the regex match.
3096
3097 Arguments:
3098 code SMTP code, may involve extended status codes
3099 codelen length of smtp code; if > 4 there's an ESC
3100 msg message text
3101 log_msg optional log message, to be adjusted with the new SMTP code
3102 check_valid if true, verify the response code
3103
3104 Returns: nothing
3105 */
3106
3107 void
3108 smtp_message_code(uschar **code, int *codelen, uschar **msg, uschar **log_msg,
3109 BOOL check_valid)
3110 {
3111 int n;
3112 int ovector[3];
3113
3114 if (!msg || !*msg) return;
3115
3116 if ((n = pcre_exec(regex_smtp_code, NULL, CS *msg, Ustrlen(*msg), 0,
3117 PCRE_EOPT, ovector, sizeof(ovector)/sizeof(int))) < 0) return;
3118
3119 if (check_valid && (*msg)[0] != (*code)[0])
3120 {
3121 log_write(0, LOG_MAIN|LOG_PANIC, "configured error code starts with "
3122 "incorrect digit (expected %c) in \"%s\"", (*code)[0], *msg);
3123 if (log_msg != NULL && *log_msg == *msg)
3124 *log_msg = string_sprintf("%s %s", *code, *log_msg + ovector[1]);
3125 }
3126 else
3127 {
3128 *code = *msg;
3129 *codelen = ovector[1]; /* Includes final space */
3130 }
3131 *msg += ovector[1]; /* Chop the code off the message */
3132 return;
3133 }
3134
3135
3136
3137
3138 /*************************************************
3139 * Handle an ACL failure *
3140 *************************************************/
3141
3142 /* This function is called when acl_check() fails. As well as calls from within
3143 this module, it is called from receive.c for an ACL after DATA. It sorts out
3144 logging the incident, and sends the error response. A message containing
3145 newlines is turned into a multiline SMTP response, but for logging, only the
3146 first line is used.
3147
3148 There's a table of default permanent failure response codes to use in
3149 globals.c, along with the table of names. VFRY is special. Despite RFC1123 it
3150 defaults disabled in Exim. However, discussion in connection with RFC 821bis
3151 (aka RFC 2821) has concluded that the response should be 252 in the disabled
3152 state, because there are broken clients that try VRFY before RCPT. A 5xx
3153 response should be given only when the address is positively known to be
3154 undeliverable. Sigh. We return 252 if there is no VRFY ACL or it provides
3155 no explicit code, but if there is one we let it know best.
3156 Also, for ETRN, 458 is given on refusal, and for AUTH, 503.
3157
3158 From Exim 4.63, it is possible to override the response code details by
3159 providing a suitable response code string at the start of the message provided
3160 in user_msg. The code's first digit is checked for validity.
3161
3162 Arguments:
3163 where where the ACL was called from
3164 rc the failure code
3165 user_msg a message that can be included in an SMTP response
3166 log_msg a message for logging
3167
3168 Returns: 0 in most cases
3169 2 if the failure code was FAIL_DROP, in which case the
3170 SMTP connection should be dropped (this value fits with the
3171 "done" variable in smtp_setup_msg() below)
3172 */
3173
3174 int
3175 smtp_handle_acl_fail(int where, int rc, uschar *user_msg, uschar *log_msg)
3176 {
3177 BOOL drop = rc == FAIL_DROP;
3178 int codelen = 3;
3179 uschar *smtp_code;
3180 uschar *lognl;
3181 uschar *sender_info = US"";
3182 uschar *what =
3183 #ifdef WITH_CONTENT_SCAN
3184 where == ACL_WHERE_MIME ? US"during MIME ACL checks" :
3185 #endif
3186 where == ACL_WHERE_PREDATA ? US"DATA" :
3187 where == ACL_WHERE_DATA ? US"after DATA" :
3188 #ifndef DISABLE_PRDR
3189 where == ACL_WHERE_PRDR ? US"after DATA PRDR" :
3190 #endif
3191 smtp_cmd_data ?
3192 string_sprintf("%s %s", acl_wherenames[where], smtp_cmd_data) :
3193 string_sprintf("%s in \"connect\" ACL", acl_wherenames[where]);
3194
3195 if (drop) rc = FAIL;
3196
3197 /* Set the default SMTP code, and allow a user message to change it. */
3198
3199 smtp_code = rc == FAIL ? acl_wherecodes[where] : US"451";
3200 smtp_message_code(&smtp_code, &codelen, &user_msg, &log_msg,
3201 where != ACL_WHERE_VRFY);
3202
3203 /* We used to have sender_address here; however, there was a bug that was not
3204 updating sender_address after a rewrite during a verify. When this bug was
3205 fixed, sender_address at this point became the rewritten address. I'm not sure
3206 this is what should be logged, so I've changed to logging the unrewritten
3207 address to retain backward compatibility. */
3208
3209 #ifndef WITH_CONTENT_SCAN
3210 if (where == ACL_WHERE_RCPT || where == ACL_WHERE_DATA)
3211 #else
3212 if (where == ACL_WHERE_RCPT || where == ACL_WHERE_DATA || where == ACL_WHERE_MIME)
3213 #endif
3214 {
3215 sender_info = string_sprintf("F=<%s>%s%s%s%s ",
3216 sender_address_unrewritten ? sender_address_unrewritten : sender_address,
3217 sender_host_authenticated ? US" A=" : US"",
3218 sender_host_authenticated ? sender_host_authenticated : US"",
3219 sender_host_authenticated && authenticated_id ? US":" : US"",
3220 sender_host_authenticated && authenticated_id ? authenticated_id : US""
3221 );
3222 }
3223
3224 /* If there's been a sender verification failure with a specific message, and
3225 we have not sent a response about it yet, do so now, as a preliminary line for
3226 failures, but not defers. However, always log it for defer, and log it for fail
3227 unless the sender_verify_fail log selector has been turned off. */
3228
3229 if (sender_verified_failed &&
3230 !testflag(sender_verified_failed, af_sverify_told))
3231 {
3232 BOOL save_rcpt_in_progress = rcpt_in_progress;
3233 rcpt_in_progress = FALSE; /* So as not to treat these as the error */
3234
3235 setflag(sender_verified_failed, af_sverify_told);
3236
3237 if (rc != FAIL || LOGGING(sender_verify_fail))
3238 log_write(0, LOG_MAIN|LOG_REJECT, "%s sender verify %s for <%s>%s",
3239 host_and_ident(TRUE),
3240 ((sender_verified_failed->special_action & 255) == DEFER)? "defer":"fail",
3241 sender_verified_failed->address,
3242 (sender_verified_failed->message == NULL)? US"" :
3243 string_sprintf(": %s", sender_verified_failed->message));
3244
3245 if (rc == FAIL && sender_verified_failed->user_message)
3246 smtp_respond(smtp_code, codelen, FALSE, string_sprintf(
3247 testflag(sender_verified_failed, af_verify_pmfail)?
3248 "Postmaster verification failed while checking <%s>\n%s\n"
3249 "Several RFCs state that you are required to have a postmaster\n"
3250 "mailbox for each mail domain. This host does not accept mail\n"
3251 "from domains whose servers reject the postmaster address."
3252 :
3253 testflag(sender_verified_failed, af_verify_nsfail)?
3254 "Callback setup failed while verifying <%s>\n%s\n"
3255 "The initial connection, or a HELO or MAIL FROM:<> command was\n"
3256 "rejected. Refusing MAIL FROM:<> does not help fight spam, disregards\n"
3257 "RFC requirements, and stops you from receiving standard bounce\n"
3258 "messages. This host does not accept mail from domains whose servers\n"
3259 "refuse bounces."
3260 :
3261 "Verification failed for <%s>\n%s",
3262 sender_verified_failed->address,
3263 sender_verified_failed->user_message));
3264
3265 rcpt_in_progress = save_rcpt_in_progress;
3266 }
3267
3268 /* Sort out text for logging */
3269
3270 log_msg = log_msg ? string_sprintf(": %s", log_msg) : US"";
3271 if ((lognl = Ustrchr(log_msg, '\n'))) *lognl = 0;
3272
3273 /* Send permanent failure response to the command, but the code used isn't
3274 always a 5xx one - see comments at the start of this function. If the original
3275 rc was FAIL_DROP we drop the connection and yield 2. */
3276
3277 if (rc == FAIL)
3278 smtp_respond(smtp_code, codelen, TRUE,
3279 user_msg ? user_msg : US"Administrative prohibition");
3280
3281 /* Send temporary failure response to the command. Don't give any details,
3282 unless acl_temp_details is set. This is TRUE for a callout defer, a "defer"
3283 verb, and for a header verify when smtp_return_error_details is set.
3284
3285 This conditional logic is all somewhat of a mess because of the odd
3286 interactions between temp_details and return_error_details. One day it should
3287 be re-implemented in a tidier fashion. */
3288
3289 else
3290 if (acl_temp_details && user_msg)
3291 {
3292 if ( smtp_return_error_details
3293 && sender_verified_failed
3294 && sender_verified_failed->message
3295 )
3296 smtp_respond(smtp_code, codelen, FALSE, sender_verified_failed->message);
3297
3298 smtp_respond(smtp_code, codelen, TRUE, user_msg);
3299 }
3300 else
3301 smtp_respond(smtp_code, codelen, TRUE,
3302 US"Temporary local problem - please try later");
3303
3304 /* Log the incident to the logs that are specified by log_reject_target
3305 (default main, reject). This can be empty to suppress logging of rejections. If
3306 the connection is not forcibly to be dropped, return 0. Otherwise, log why it
3307 is closing if required and return 2. */
3308
3309 if (log_reject_target != 0)
3310 {
3311 #ifdef SUPPORT_TLS
3312 gstring * g = s_tlslog(NULL);
3313 uschar * tls = string_from_gstring(g);
3314 if (!tls) tls = US"";
3315 #else
3316 uschar * tls = US"";
3317 #endif
3318 log_write(where == ACL_WHERE_CONNECT ? L_connection_reject : 0,
3319 log_reject_target, "%s%s%s %s%srejected %s%s",
3320 LOGGING(dnssec) && sender_host_dnssec ? US" DS" : US"",
3321 host_and_ident(TRUE),
3322 tls,
3323 sender_info,
3324 rc == FAIL ? US"" : US"temporarily ",
3325 what, log_msg);
3326 }
3327
3328 if (!drop) return 0;
3329
3330 log_write(L_smtp_connection, LOG_MAIN, "%s closed by DROP in ACL",
3331 smtp_get_connection_info());
3332
3333 /* Run the not-quit ACL, but without any custom messages. This should not be a
3334 problem, because we get here only if some other ACL has issued "drop", and
3335 in that case, *its* custom messages will have been used above. */
3336
3337 smtp_notquit_exit(US"acl-drop", NULL, NULL);
3338 return 2;
3339 }
3340
3341
3342
3343
3344 /*************************************************
3345 * Handle SMTP exit when QUIT is not given *
3346 *************************************************/
3347
3348 /* This function provides a logging/statistics hook for when an SMTP connection
3349 is dropped on the floor or the other end goes away. It's a global function
3350 because it's called from receive.c as well as this module. As well as running
3351 the NOTQUIT ACL, if there is one, this function also outputs a final SMTP
3352 response, either with a custom message from the ACL, or using a default. There
3353 is one case, however, when no message is output - after "drop". In that case,
3354 the ACL that obeyed "drop" has already supplied the custom message, and NULL is
3355 passed to this function.
3356
3357 In case things go wrong while processing this function, causing an error that
3358 may re-enter this function, there is a recursion check.
3359
3360 Arguments:
3361 reason What $smtp_notquit_reason will be set to in the ACL;
3362 if NULL, the ACL is not run
3363 code The error code to return as part of the response
3364 defaultrespond The default message if there's no user_msg
3365
3366 Returns: Nothing
3367 */
3368
3369 void
3370 smtp_notquit_exit(uschar *reason, uschar *code, uschar *defaultrespond, ...)
3371 {
3372 int rc;
3373 uschar *user_msg = NULL;
3374 uschar *log_msg = NULL;
3375
3376 /* Check for recursive acll */
3377
3378 if (smtp_exit_function_called)
3379 {
3380 log_write(0, LOG_PANIC, "smtp_notquit_exit() called more than once (%s)",
3381 reason);
3382 return;
3383 }
3384 smtp_exit_function_called = TRUE;
3385
3386 /* Call the not-QUIT ACL, if there is one, unless no reason is given. */
3387
3388 if (acl_smtp_notquit && reason)
3389 {
3390 smtp_notquit_reason = reason;
3391 if ((rc = acl_check(ACL_WHERE_NOTQUIT, NULL, acl_smtp_notquit, &user_msg,
3392 &log_msg)) == ERROR)
3393 log_write(0, LOG_MAIN|LOG_PANIC, "ACL for not-QUIT returned ERROR: %s",
3394 log_msg);
3395 }
3396
3397 /* Write an SMTP response if we are expected to give one. As the default
3398 responses are all internal, they should always fit in the buffer, but code a
3399 warning, just in case. Note that string_vformat() still leaves a complete
3400 string, even if it is incomplete. */
3401
3402 if (code && defaultrespond)
3403 {
3404 if (user_msg)
3405 smtp_respond(code, 3, TRUE, user_msg);
3406 else
3407 {
3408 uschar buffer[128];
3409 va_list ap;
3410 va_start(ap, defaultrespond);
3411 if (!string_vformat(buffer, sizeof(buffer), CS defaultrespond, ap))
3412 log_write(0, LOG_MAIN|LOG_PANIC, "string too large in smtp_notquit_exit()");
3413 smtp_printf("%s %s\r\n", FALSE, code, buffer);
3414 va_end(ap);
3415 }
3416 mac_smtp_fflush();
3417 }
3418 }
3419
3420
3421
3422
3423 /*************************************************
3424 * Verify HELO argument *
3425 *************************************************/
3426
3427 /* This function is called if helo_verify_hosts or helo_try_verify_hosts is
3428 matched. It is also called from ACL processing if verify = helo is used and
3429 verification was not previously tried (i.e. helo_try_verify_hosts was not
3430 matched). The result of its processing is to set helo_verified and
3431 helo_verify_failed. These variables should both be FALSE for this function to
3432 be called.
3433
3434 Note that EHLO/HELO is legitimately allowed to quote an address literal. Allow
3435 for IPv6 ::ffff: literals.
3436
3437 Argument: none
3438 Returns: TRUE if testing was completed;
3439 FALSE on a temporary failure
3440 */
3441
3442 BOOL
3443 smtp_verify_helo(void)
3444 {
3445 BOOL yield = TRUE;
3446
3447 HDEBUG(D_receive) debug_printf("verifying EHLO/HELO argument \"%s\"\n",
3448 sender_helo_name);
3449
3450 if (sender_helo_name == NULL)
3451 {
3452 HDEBUG(D_receive) debug_printf("no EHLO/HELO command was issued\n");
3453 }
3454
3455 /* Deal with the case of -bs without an IP address */
3456
3457 else if (sender_host_address == NULL)
3458 {
3459 HDEBUG(D_receive) debug_printf("no client IP address: assume success\n");
3460 helo_verified = TRUE;
3461 }
3462
3463 /* Deal with the more common case when there is a sending IP address */
3464
3465 else if (sender_helo_name[0] == '[')
3466 {
3467 helo_verified = Ustrncmp(sender_helo_name+1, sender_host_address,
3468 Ustrlen(sender_host_address)) == 0;
3469
3470 #if HAVE_IPV6
3471 if (!helo_verified)
3472 {
3473 if (strncmpic(sender_host_address, US"::ffff:", 7) == 0)
3474 helo_verified = Ustrncmp(sender_helo_name + 1,
3475 sender_host_address + 7, Ustrlen(sender_host_address) - 7) == 0;
3476 }
3477 #endif
3478
3479 HDEBUG(D_receive)
3480 { if (helo_verified) debug_printf("matched host address\n"); }
3481 }
3482
3483 /* Do a reverse lookup if one hasn't already given a positive or negative
3484 response. If that fails, or the name doesn't match, try checking with a forward
3485 lookup. */
3486
3487 else
3488 {
3489 if (sender_host_name == NULL && !host_lookup_failed)
3490 yield = host_name_lookup() != DEFER;
3491
3492 /* If a host name is known, check it and all its aliases. */
3493
3494 if (sender_host_name)
3495 if ((helo_verified = strcmpic(sender_host_name, sender_helo_name) == 0))
3496 {
3497 sender_helo_dnssec = sender_host_dnssec;
3498 HDEBUG(D_receive) debug_printf("matched host name\n");
3499 }
3500 else
3501 {
3502 uschar **aliases = sender_host_aliases;
3503 while (*aliases)
3504 if ((helo_verified = strcmpic(*aliases++, sender_helo_name) == 0))
3505 {
3506 sender_helo_dnssec = sender_host_dnssec;
3507 break;
3508 }
3509
3510 HDEBUG(D_receive) if (helo_verified)
3511 debug_printf("matched alias %s\n", *(--aliases));
3512 }
3513
3514 /* Final attempt: try a forward lookup of the helo name */
3515
3516 if (!helo_verified)
3517 {
3518 int rc;
3519 host_item h;
3520 dnssec_domains d;
3521 host_item *hh;
3522
3523 h.name = sender_helo_name;
3524 h.address = NULL;
3525 h.mx = MX_NONE;
3526 h.next = NULL;
3527 d.request = US"*";
3528 d.require = US"";
3529
3530 HDEBUG(D_receive) debug_printf("getting IP address for %s\n",
3531 sender_helo_name);
3532 rc = host_find_bydns(&h, NULL, HOST_FIND_BY_A | HOST_FIND_BY_AAAA,
3533 NULL, NULL, NULL, &d, NULL, NULL);
3534 if (rc == HOST_FOUND || rc == HOST_FOUND_LOCAL)
3535 for (hh = &h; hh; hh = hh->next)
3536 if (Ustrcmp(hh->address, sender_host_address) == 0)
3537 {
3538 helo_verified = TRUE;
3539 if (h.dnssec == DS_YES) sender_helo_dnssec = TRUE;
3540 HDEBUG(D_receive)
3541 {
3542 debug_printf("IP address for %s matches calling address\n"
3543 "Forward DNS security status: %sverified\n",
3544 sender_helo_name, sender_helo_dnssec ? "" : "un");
3545 }
3546 break;
3547 }
3548 }
3549 }
3550
3551 if (!helo_verified) helo_verify_failed = TRUE; /* We've tried ... */
3552 return yield;
3553 }
3554
3555
3556
3557
3558 /*************************************************
3559 * Send user response message *
3560 *************************************************/
3561
3562 /* This function is passed a default response code and a user message. It calls
3563 smtp_message_code() to check and possibly modify the response code, and then
3564 calls smtp_respond() to transmit the response. I put this into a function
3565 just to avoid a lot of repetition.
3566
3567 Arguments:
3568 code the response code
3569 user_msg the user message
3570
3571 Returns: nothing
3572 */
3573
3574 static void
3575 smtp_user_msg(uschar *code, uschar *user_msg)
3576 {
3577 int len = 3;
3578 smtp_message_code(&code, &len, &user_msg, NULL, TRUE);
3579 smtp_respond(code, len, TRUE, user_msg);
3580 }
3581
3582
3583
3584 static int
3585 smtp_in_auth(auth_instance *au, uschar ** s, uschar ** ss)
3586 {
3587 const uschar *set_id = NULL;
3588 int rc, i;
3589
3590 /* Run the checking code, passing the remainder of the command line as
3591 data. Initials the $auth<n> variables as empty. Initialize $0 empty and set
3592 it as the only set numerical variable. The authenticator may set $auth<n>
3593 and also set other numeric variables. The $auth<n> variables are preferred
3594 nowadays; the numerical variables remain for backwards compatibility.
3595
3596 Afterwards, have a go at expanding the set_id string, even if
3597 authentication failed - for bad passwords it can be useful to log the
3598 userid. On success, require set_id to expand and exist, and put it in
3599 authenticated_id. Save this in permanent store, as the working store gets
3600 reset at HELO, RSET, etc. */
3601
3602 for (i = 0; i < AUTH_VARS; i++) auth_vars[i] = NULL;
3603 expand_nmax = 0;
3604 expand_nlength[0] = 0; /* $0 contains nothing */
3605
3606 rc = (au->info->servercode)(au, smtp_cmd_data);
3607 if (au->set_id) set_id = expand_string(au->set_id);
3608 expand_nmax = -1; /* Reset numeric variables */
3609 for (i = 0; i < AUTH_VARS; i++) auth_vars[i] = NULL; /* Reset $auth<n> */
3610
3611 /* The value of authenticated_id is stored in the spool file and printed in
3612 log lines. It must not contain binary zeros or newline characters. In
3613 normal use, it never will, but when playing around or testing, this error
3614 can (did) happen. To guard against this, ensure that the id contains only
3615 printing characters. */
3616
3617 if (set_id) set_id = string_printing(set_id);
3618
3619 /* For the non-OK cases, set up additional logging data if set_id
3620 is not empty. */
3621
3622 if (rc != OK)
3623 set_id = set_id && *set_id
3624 ? string_sprintf(" (set_id=%s)", set_id) : US"";
3625
3626 /* Switch on the result */
3627
3628 switch(rc)
3629 {
3630 case OK:
3631 if (!au->set_id || set_id) /* Complete success */
3632 {
3633 if (set_id) authenticated_id = string_copy_malloc(set_id);
3634 sender_host_authenticated = au->name;
3635 sender_host_auth_pubname = au->public_name;
3636 authentication_failed = FALSE;
3637 authenticated_fail_id = NULL; /* Impossible to already be set? */
3638
3639 received_protocol =
3640 (sender_host_address ? protocols : protocols_local)
3641 [pextend + pauthed + (tls_in.active >= 0 ? pcrpted:0)];
3642 *s = *ss = US"235 Authentication succeeded";
3643 authenticated_by = au;
3644 break;
3645 }
3646
3647 /* Authentication succeeded, but we failed to expand the set_id string.
3648 Treat this as a temporary error. */
3649
3650 auth_defer_msg = expand_string_message;
3651 /* Fall through */
3652
3653 case DEFER:
3654 if (set_id) authenticated_fail_id = string_copy_malloc(set_id);
3655 *s = string_sprintf("435 Unable to authenticate at present%s",
3656 auth_defer_user_msg);
3657 *ss = string_sprintf("435 Unable to authenticate at present%s: %s",
3658 set_id, auth_defer_msg);
3659 break;
3660
3661 case BAD64:
3662 *s = *ss = US"501 Invalid base64 data";
3663 break;
3664
3665 case CANCELLED:
3666 *s = *ss = US"501 Authentication cancelled";
3667 break;
3668
3669 case UNEXPECTED:
3670 *s = *ss = US"553 Initial data not expected";
3671 break;
3672
3673 case FAIL:
3674 if (set_id) authenticated_fail_id = string_copy_malloc(set_id);
3675 *s = US"535 Incorrect authentication data";
3676 *ss = string_sprintf("535 Incorrect authentication data%s", set_id);
3677 break;
3678
3679 default:
3680 if (set_id) authenticated_fail_id = string_copy_malloc(set_id);
3681 *s = US"435 Internal error";
3682 *ss = string_sprintf("435 Internal error%s: return %d from authentication "
3683 "check", set_id, rc);
3684 break;
3685 }
3686
3687 return rc;
3688 }
3689
3690
3691
3692
3693
3694 static int
3695 qualify_recipient(uschar ** recipient, uschar * smtp_cmd_data, uschar * tag)
3696 {
3697 int rd;
3698 if (allow_unqualified_recipient || strcmpic(*recipient, US"postmaster") == 0)
3699 {
3700 DEBUG(D_receive) debug_printf("unqualified address %s accepted\n",
3701 *recipient);
3702 rd = Ustrlen(recipient) + 1;
3703 *recipient = rewrite_address_qualify(*recipient, TRUE);
3704 return rd;
3705 }
3706 smtp_printf("501 %s: recipient address must contain a domain\r\n", FALSE,
3707 smtp_cmd_data);
3708 log_write(L_smtp_syntax_error,
3709 LOG_MAIN|LOG_REJECT, "unqualified %s rejected: <%s> %s%s",
3710 tag, *recipient, host_and_ident(TRUE), host_lookup_msg);
3711 return 0;
3712 }
3713
3714
3715
3716
3717 static void
3718 smtp_quit_handler(uschar ** user_msgp, uschar ** log_msgp)
3719 {
3720 HAD(SCH_QUIT);
3721 incomplete_transaction_log(US"QUIT");
3722 if (acl_smtp_quit)
3723 {
3724 int rc = acl_check(ACL_WHERE_QUIT, NULL, acl_smtp_quit, user_msgp, log_msgp);
3725 if (rc == ERROR)
3726 log_write(0, LOG_MAIN|LOG_PANIC, "ACL for QUIT returned ERROR: %s",
3727 *log_msgp);
3728 }
3729 if (*user_msgp)
3730 smtp_respond(US"221", 3, TRUE, *user_msgp);
3731 else
3732 smtp_printf("221 %s closing connection\r\n", FALSE, smtp_active_hostname);
3733
3734 #ifdef SUPPORT_TLS
3735 tls_close(TRUE, TLS_SHUTDOWN_NOWAIT);
3736 #endif
3737
3738 log_write(L_smtp_connection, LOG_MAIN, "%s closed by QUIT",
3739 smtp_get_connection_info());
3740 }
3741
3742
3743 static void
3744 smtp_rset_handler(void)
3745 {
3746 HAD(SCH_RSET);
3747 incomplete_transaction_log(US"RSET");
3748 smtp_printf("250 Reset OK\r\n", FALSE);
3749 cmd_list[CMD_LIST_RSET].is_mail_cmd = FALSE;
3750 }
3751
3752
3753
3754 /*************************************************
3755 * Initialize for SMTP incoming message *
3756 *************************************************/
3757
3758 /* This function conducts the initial dialogue at the start of an incoming SMTP
3759 message, and builds a list of recipients. However, if the incoming message
3760 is part of a batch (-bS option) a separate function is called since it would
3761 be messy having tests splattered about all over this function. This function
3762 therefore handles the case where interaction is occurring. The input and output
3763 files are set up in smtp_in and smtp_out.
3764
3765 The global recipients_list is set to point to a vector of recipient_item
3766 blocks, whose number is given by recipients_count. This is extended by the
3767 receive_add_recipient() function. The global variable sender_address is set to
3768 the sender's address. The yield is +1 if a message has been successfully
3769 started, 0 if a QUIT command was encountered or the connection was refused from
3770 the particular host, or -1 if the connection was lost.
3771
3772 Argument: none
3773
3774 Returns: > 0 message successfully started (reached DATA)
3775 = 0 QUIT read or end of file reached or call refused
3776 < 0 lost connection
3777 */
3778
3779 int
3780 smtp_setup_msg(void)
3781 {
3782 int done = 0;
3783 BOOL toomany = FALSE;
3784 BOOL discarded = FALSE;
3785 BOOL last_was_rej_mail = FALSE;
3786 BOOL last_was_rcpt = FALSE;
3787 void *reset_point = store_get(0);
3788
3789 DEBUG(D_receive) debug_printf("smtp_setup_msg entered\n");
3790
3791 /* Reset for start of new message. We allow one RSET not to be counted as a
3792 nonmail command, for those MTAs that insist on sending it between every
3793 message. Ditto for EHLO/HELO and for STARTTLS, to allow for going in and out of
3794 TLS between messages (an Exim client may do this if it has messages queued up
3795 for the host). Note: we do NOT reset AUTH at this point. */
3796
3797 smtp_reset(reset_point);
3798 message_ended = END_NOTSTARTED;
3799
3800 chunking_state = chunking_offered ? CHUNKING_OFFERED : CHUNKING_NOT_OFFERED;
3801
3802 cmd_list[CMD_LIST_RSET].is_mail_cmd = TRUE;
3803 cmd_list[CMD_LIST_HELO].is_mail_cmd = TRUE;
3804 cmd_list[CMD_LIST_EHLO].is_mail_cmd = TRUE;
3805 #ifdef SUPPORT_TLS
3806 cmd_list[CMD_LIST_STARTTLS].is_mail_cmd = TRUE;
3807 #endif
3808
3809 /* Set the local signal handler for SIGTERM - it tries to end off tidily */
3810
3811 os_non_restarting_signal(SIGTERM, command_sigterm_handler);
3812
3813 /* Batched SMTP is handled in a different function. */
3814
3815 if (smtp_batched_input) return smtp_setup_batch_msg();
3816
3817 /* Deal with SMTP commands. This loop is exited by setting done to a POSITIVE
3818 value. The values are 2 larger than the required yield of the function. */
3819
3820 while (done <= 0)
3821 {
3822 const uschar **argv;
3823 uschar *etrn_command;
3824 uschar *etrn_serialize_key;
3825 uschar *errmess;
3826 uschar *log_msg, *smtp_code;
3827 uschar *user_msg = NULL;
3828 uschar *recipient = NULL;
3829 uschar *hello = NULL;
3830 uschar *s, *ss;
3831 BOOL was_rej_mail = FALSE;
3832 BOOL was_rcpt = FALSE;
3833 void (*oldsignal)(int);
3834 pid_t pid;
3835 int start, end, sender_domain, recipient_domain;
3836 int rc;
3837 int c;
3838 auth_instance *au;
3839 uschar *orcpt = NULL;
3840 int flags;
3841 gstring * g;
3842
3843 #ifdef AUTH_TLS
3844 /* Check once per STARTTLS or SSL-on-connect for a TLS AUTH */
3845 if ( tls_in.active >= 0
3846 && tls_in.peercert
3847 && tls_in.certificate_verified
3848 && cmd_list[CMD_LIST_TLS_AUTH].is_mail_cmd
3849 )
3850 {
3851 cmd_list[CMD_LIST_TLS_AUTH].is_mail_cmd = FALSE;
3852
3853 for (au = auths; au; au = au->next)
3854 if (strcmpic(US"tls", au->driver_name) == 0)
3855 {
3856 if ( acl_smtp_auth
3857 && (rc = acl_check(ACL_WHERE_AUTH, NULL, acl_smtp_auth,
3858 &user_msg, &log_msg)) != OK
3859 )
3860 done = smtp_handle_acl_fail(ACL_WHERE_AUTH, rc, user_msg, log_msg);
3861 else
3862 {
3863 smtp_cmd_data = NULL;
3864
3865 if (smtp_in_auth(au, &s, &ss) == OK)
3866 { DEBUG(D_auth) debug_printf("tls auth succeeded\n"); }
3867 else
3868 { DEBUG(D_auth) debug_printf("tls auth not succeeded\n"); }
3869 }
3870 break;
3871 }
3872 }
3873 #endif
3874
3875 #ifdef TCP_QUICKACK
3876 if (smtp_in) /* Avoid pure-ACKs while in cmd pingpong phase */
3877 (void) setsockopt(fileno(smtp_in), IPPROTO_TCP, TCP_QUICKACK,
3878 US &off, sizeof(off));
3879 #endif
3880
3881 switch(smtp_read_command(TRUE, GETC_BUFFER_UNLIMITED))
3882 {
3883 /* The AUTH command is not permitted to occur inside a transaction, and may
3884 occur successfully only once per connection. Actually, that isn't quite
3885 true. When TLS is started, all previous information about a connection must
3886 be discarded, so a new AUTH is permitted at that time.
3887
3888 AUTH may only be used when it has been advertised. However, it seems that
3889 there are clients that send AUTH when it hasn't been advertised, some of
3890 them even doing this after HELO. And there are MTAs that accept this. Sigh.
3891 So there's a get-out that allows this to happen.
3892
3893 AUTH is initially labelled as a "nonmail command" so that one occurrence
3894 doesn't get counted. We change the label here so that multiple failing
3895 AUTHS will eventually hit the nonmail threshold. */
3896
3897 case AUTH_CMD:
3898 HAD(SCH_AUTH);
3899 authentication_failed = TRUE;
3900 cmd_list[CMD_LIST_AUTH].is_mail_cmd = FALSE;
3901
3902 if (!auth_advertised && !allow_auth_unadvertised)
3903 {
3904 done = synprot_error(L_smtp_protocol_error, 503, NULL,
3905 US"AUTH command used when not advertised");
3906 break;
3907 }
3908 if (sender_host_authenticated)
3909 {
3910 done = synprot_error(L_smtp_protocol_error, 503, NULL,
3911 US"already authenticated");
3912 break;
3913 }
3914 if (sender_address)
3915 {
3916 done = synprot_error(L_smtp_protocol_error, 503, NULL,
3917 US"not permitted in mail transaction");
3918 break;
3919 }
3920
3921 /* Check the ACL */
3922
3923 if ( acl_smtp_auth
3924 && (rc = acl_check(ACL_WHERE_AUTH, NULL, acl_smtp_auth,
3925 &user_msg, &log_msg)) != OK
3926 )
3927 {
3928 done = smtp_handle_acl_fail(ACL_WHERE_AUTH, rc, user_msg, log_msg);
3929 break;
3930 }
3931
3932 /* Find the name of the requested authentication mechanism. */
3933
3934 s = smtp_cmd_data;
3935 while ((c = *smtp_cmd_data) != 0 && !isspace(c))
3936 {
3937 if (!isalnum(c) && c != '-' && c != '_')
3938 {
3939 done = synprot_error(L_smtp_syntax_error, 501, NULL,
3940 US"invalid character in authentication mechanism name");
3941 goto COMMAND_LOOP;
3942 }
3943 smtp_cmd_data++;
3944 }
3945
3946 /* If not at the end of the line, we must be at white space. Terminate the
3947 name and move the pointer on to any data that may be present. */
3948
3949 if (*smtp_cmd_data != 0)
3950 {
3951 *smtp_cmd_data++ = 0;
3952 while (isspace(*smtp_cmd_data)) smtp_cmd_data++;
3953 }
3954
3955 /* Search for an authentication mechanism which is configured for use
3956 as a server and which has been advertised (unless, sigh, allow_auth_
3957 unadvertised is set). */
3958
3959 for (au = auths; au; au = au->next)
3960 if (strcmpic(s, au->public_name) == 0 && au->server &&
3961 (au->advertised || allow_auth_unadvertised))
3962 break;
3963
3964 if (au)
3965 {
3966 c = smtp_in_auth(au, &s, &ss);
3967
3968 smtp_printf("%s\r\n", FALSE, s);
3969 if (c != OK)
3970 log_write(0, LOG_MAIN|LOG_REJECT, "%s authenticator failed for %s: %s",
3971 au->name, host_and_ident(FALSE), ss);
3972 }
3973 else
3974 done = synprot_error(L_smtp_protocol_error, 504, NULL,
3975 string_sprintf("%s authentication mechanism not supported", s));
3976
3977 break; /* AUTH_CMD */
3978
3979 /* The HELO/EHLO commands are permitted to appear in the middle of a
3980 session as well as at the beginning. They have the effect of a reset in
3981 addition to their other functions. Their absence at the start cannot be
3982 taken to be an error.
3983
3984 RFC 2821 says:
3985
3986 If the EHLO command is not acceptable to the SMTP server, 501, 500,
3987 or 502 failure replies MUST be returned as appropriate. The SMTP
3988 server MUST stay in the same state after transmitting these replies
3989 that it was in before the EHLO was received.
3990
3991 Therefore, we do not do the reset until after checking the command for
3992 acceptability. This change was made for Exim release 4.11. Previously
3993 it did the reset first. */
3994
3995 case HELO_CMD:
3996 HAD(SCH_HELO);
3997 hello = US"HELO";
3998 esmtp = FALSE;
3999 goto HELO_EHLO;
4000
4001 case EHLO_CMD:
4002 HAD(SCH_EHLO);
4003 hello = US"EHLO";
4004 esmtp = TRUE;
4005
4006 HELO_EHLO: /* Common code for HELO and EHLO */
4007 cmd_list[CMD_LIST_HELO].is_mail_cmd = FALSE;
4008 cmd_list[CMD_LIST_EHLO].is_mail_cmd = FALSE;
4009
4010 /* Reject the HELO if its argument was invalid or non-existent. A
4011 successful check causes the argument to be saved in malloc store. */
4012
4013 if (!check_helo(smtp_cmd_data))
4014 {
4015 smtp_printf("501 Syntactically invalid %s argument(s)\r\n", FALSE, hello);
4016
4017 log_write(0, LOG_MAIN|LOG_REJECT, "rejected %s from %s: syntactically "
4018 "invalid argument(s): %s", hello, host_and_ident(FALSE),
4019 (*smtp_cmd_argument == 0)? US"(no argument given)" :
4020 string_printing(smtp_cmd_argument));
4021
4022 if (++synprot_error_count > smtp_max_synprot_errors)
4023 {
4024 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
4025 "syntax or protocol errors (last command was \"%s\")",
4026 host_and_ident(FALSE), string_printing(smtp_cmd_buffer));
4027 done = 1;
4028 }
4029
4030 break;
4031 }
4032
4033 /* If sender_host_unknown is true, we have got here via the -bs interface,
4034 not called from inetd. Otherwise, we are running an IP connection and the
4035 host address will be set. If the helo name is the primary name of this
4036 host and we haven't done a reverse lookup, force one now. If helo_required
4037 is set, ensure that the HELO name matches the actual host. If helo_verify
4038 is set, do the same check, but softly. */
4039
4040 if (!sender_host_unknown)
4041 {
4042 BOOL old_helo_verified = helo_verified;
4043 uschar *p = smtp_cmd_data;
4044
4045 while (*p != 0 && !isspace(*p)) { *p = tolower(*p); p++; }
4046 *p = 0;
4047
4048 /* Force a reverse lookup if HELO quoted something in helo_lookup_domains
4049 because otherwise the log can be confusing. */
4050
4051 if ( !sender_host_name
4052 && (deliver_domain = sender_helo_name, /* set $domain */
4053 match_isinlist(sender_helo_name, CUSS &helo_lookup_domains, 0,
4054 &domainlist_anchor, NULL, MCL_DOMAIN, TRUE, NULL)) == OK)
4055 (void)host_name_lookup();
4056
4057 /* Rebuild the fullhost info to include the HELO name (and the real name
4058 if it was looked up.) */
4059
4060 host_build_sender_fullhost(); /* Rebuild */
4061 set_process_info("handling%s incoming connection from %s",
4062 (tls_in.active >= 0)? " TLS" : "", host_and_ident(FALSE));
4063
4064 /* Verify if configured. This doesn't give much security, but it does
4065 make some people happy to be able to do it. If helo_required is set,
4066 (host matches helo_verify_hosts) failure forces rejection. If helo_verify
4067 is set (host matches helo_try_verify_hosts), it does not. This is perhaps
4068 now obsolescent, since the verification can now be requested selectively
4069 at ACL time. */
4070
4071 helo_verified = helo_verify_failed = sender_helo_dnssec = FALSE;
4072 if (helo_required || helo_verify)
4073 {
4074 BOOL tempfail = !smtp_verify_helo();
4075 if (!helo_verified)
4076 {
4077 if (helo_required)
4078 {
4079 smtp_printf("%d %s argument does not match calling host\r\n", FALSE,
4080 tempfail? 451 : 550, hello);
4081 log_write(0, LOG_MAIN|LOG_REJECT, "%srejected \"%s %s\" from %s",
4082 tempfail? "temporarily " : "",
4083 hello, sender_helo_name, host_and_ident(FALSE));
4084 helo_verified = old_helo_verified;
4085 break; /* End of HELO/EHLO processing */
4086 }
4087 HDEBUG(D_all) debug_printf("%s verification failed but host is in "
4088 "helo_try_verify_hosts\n", hello);
4089 }
4090 }
4091 }
4092
4093 #ifdef SUPPORT_SPF
4094 /* set up SPF context */
4095 spf_init(sender_helo_name, sender_host_address);
4096 #endif
4097
4098 /* Apply an ACL check if one is defined; afterwards, recheck
4099 synchronization in case the client started sending in a delay. */
4100
4101 if (acl_smtp_helo)
4102 if ((rc = acl_check(ACL_WHERE_HELO, NULL, acl_smtp_helo,
4103 &user_msg, &log_msg)) != OK)
4104 {
4105 done = smtp_handle_acl_fail(ACL_WHERE_HELO, rc, user_msg, log_msg);
4106 if (sender_helo_name)
4107 {
4108 store_free(sender_helo_name);
4109 sender_helo_name = NULL;
4110 }
4111 host_build_sender_fullhost(); /* Rebuild */
4112 break;
4113 }
4114 else if (!check_sync()) goto SYNC_FAILURE;
4115
4116 /* Generate an OK reply. The default string includes the ident if present,
4117 and also the IP address if present. Reflecting back the ident is intended
4118 as a deterrent to mail forgers. For maximum efficiency, and also because
4119 some broken systems expect each response to be in a single packet, arrange<