1 /*
2  * Copyright (c) 1983 Eric P. Allman
3  * Copyright (c) 1988 Regents of the University of California.
4  * All rights reserved.
5  *
6  * %sccs.include.redist.c%
7  */
8 
9 # include "sendmail.h"
10 
11 #ifndef lint
12 #ifdef SMTP
13 static char sccsid[] = "@(#)srvrsmtp.c	6.19 (Berkeley) 02/28/93 (with SMTP)";
14 #else
15 static char sccsid[] = "@(#)srvrsmtp.c	6.19 (Berkeley) 02/28/93 (without SMTP)";
16 #endif
17 #endif /* not lint */
18 
19 # include <errno.h>
20 # include <signal.h>
21 
22 # ifdef SMTP
23 
24 /*
25 **  SMTP -- run the SMTP protocol.
26 **
27 **	Parameters:
28 **		none.
29 **
30 **	Returns:
31 **		never.
32 **
33 **	Side Effects:
34 **		Reads commands from the input channel and processes
35 **			them.
36 */
37 
38 struct cmd
39 {
40 	char	*cmdname;	/* command name */
41 	int	cmdcode;	/* internal code, see below */
42 };
43 
44 /* values for cmdcode */
45 # define CMDERROR	0	/* bad command */
46 # define CMDMAIL	1	/* mail -- designate sender */
47 # define CMDRCPT	2	/* rcpt -- designate recipient */
48 # define CMDDATA	3	/* data -- send message text */
49 # define CMDRSET	4	/* rset -- reset state */
50 # define CMDVRFY	5	/* vrfy -- verify address */
51 # define CMDEXPN	6	/* expn -- expand address */
52 # define CMDNOOP	7	/* noop -- do nothing */
53 # define CMDQUIT	8	/* quit -- close connection and die */
54 # define CMDHELO	9	/* helo -- be polite */
55 # define CMDHELP	10	/* help -- give usage info */
56 # define CMDEHLO	11	/* ehlo -- extended helo (RFC 1425) */
57 /* non-standard commands */
58 # define CMDONEX	16	/* onex -- sending one transaction only */
59 # define CMDVERB	17	/* verb -- go into verbose mode */
60 /* debugging-only commands, only enabled if SMTPDEBUG is defined */
61 # define CMDDBGQSHOW	24	/* showq -- show send queue */
62 # define CMDDBGDEBUG	25	/* debug -- set debug mode */
63 
64 static struct cmd	CmdTab[] =
65 {
66 	"mail",		CMDMAIL,
67 	"rcpt",		CMDRCPT,
68 	"data",		CMDDATA,
69 	"rset",		CMDRSET,
70 	"vrfy",		CMDVRFY,
71 	"expn",		CMDEXPN,
72 	"help",		CMDHELP,
73 	"noop",		CMDNOOP,
74 	"quit",		CMDQUIT,
75 	"helo",		CMDHELO,
76 	"ehlo",		CMDEHLO,
77 	"verb",		CMDVERB,
78 	"onex",		CMDONEX,
79 	/*
80 	 * remaining commands are here only
81 	 * to trap and log attempts to use them
82 	 */
83 	"showq",	CMDDBGQSHOW,
84 	"debug",	CMDDBGDEBUG,
85 	NULL,		CMDERROR,
86 };
87 
88 bool	InChild = FALSE;		/* true if running in a subprocess */
89 bool	OneXact = FALSE;		/* one xaction only this run */
90 
91 #define EX_QUIT		22		/* special code for QUIT command */
92 
93 smtp(e)
94 	register ENVELOPE *e;
95 {
96 	register char *p;
97 	register struct cmd *c;
98 	char *cmd;
99 	static char *skipword();
100 	auto ADDRESS *vrfyqueue;
101 	ADDRESS *a;
102 	char *sendinghost;
103 	bool gotmail;			/* mail command received */
104 	bool gothello;			/* helo command received */
105 	bool vrfy;			/* set if this is a vrfy command */
106 	char *protocol;			/* sending protocol */
107 	char inp[MAXLINE];
108 	char cmdbuf[MAXLINE];
109 	extern char Version[];
110 	extern char *macvalue();
111 	extern ADDRESS *recipient();
112 	extern ENVELOPE BlankEnvelope;
113 	extern ENVELOPE *newenvelope();
114 
115 	gotmail = FALSE;
116 	if (OutChannel != stdout)
117 	{
118 		/* arrange for debugging output to go to remote host */
119 		(void) close(1);
120 		(void) dup(fileno(OutChannel));
121 	}
122 	settime(e);
123 	CurHostName = RealHostName;
124 	setproctitle("srvrsmtp %s", CurHostName);
125 	expand("\201e", inp, &inp[sizeof inp], e);
126 	message("220 %s", inp);
127 	SmtpPhase = "startup";
128 	sendinghost = NULL;
129 	gothello = FALSE;
130 	for (;;)
131 	{
132 		/* arrange for backout */
133 		if (setjmp(TopFrame) > 0 && InChild)
134 			finis();
135 		QuickAbort = FALSE;
136 		HoldErrs = FALSE;
137 		LogUsrErrs = FALSE;
138 		e->e_flags &= ~EF_VRFYONLY;
139 
140 		/* setup for the read */
141 		e->e_to = NULL;
142 		Errors = 0;
143 		(void) fflush(stdout);
144 
145 		/* read the input line */
146 		p = sfgets(inp, sizeof inp, InChannel, TimeOuts.to_nextcommand);
147 
148 		/* handle errors */
149 		if (p == NULL)
150 		{
151 			/* end of file, just die */
152 			message("421 %s Lost input channel from %s",
153 				MyHostName, CurHostName);
154 #ifdef LOG
155 			if (LogLevel > 1)
156 				syslog(LOG_NOTICE, "lost input channel from %s",
157 					CurHostName);
158 #endif
159 			if (InChild)
160 				ExitStat = EX_QUIT;
161 			finis();
162 		}
163 
164 		/* clean up end of line */
165 		fixcrlf(inp, TRUE);
166 
167 		/* echo command to transcript */
168 		if (e->e_xfp != NULL)
169 			fprintf(e->e_xfp, "<<< %s\n", inp);
170 
171 		/* break off command */
172 		for (p = inp; isascii(*p) && isspace(*p); p++)
173 			continue;
174 		cmd = cmdbuf;
175 		while (*p != '\0' &&
176 		       !(isascii(*p) && isspace(*p)) &&
177 		       cmd < &cmdbuf[sizeof cmdbuf - 2])
178 			*cmd++ = *p++;
179 		*cmd = '\0';
180 
181 		/* throw away leading whitespace */
182 		while (isascii(*p) && isspace(*p))
183 			p++;
184 
185 		/* decode command */
186 		for (c = CmdTab; c->cmdname != NULL; c++)
187 		{
188 			if (!strcasecmp(c->cmdname, cmdbuf))
189 				break;
190 		}
191 
192 		/* reset errors */
193 		errno = 0;
194 
195 		/* process command */
196 		switch (c->cmdcode)
197 		{
198 		  case CMDHELO:		/* hello -- introduce yourself */
199 		  case CMDEHLO:		/* extended hello */
200 			if (c->cmdcode == CMDEHLO)
201 			{
202 				protocol = "ESMTP";
203 				SmtpPhase = "EHLO";
204 			}
205 			else
206 			{
207 				protocol = "SMTP";
208 				SmtpPhase = "HELO";
209 			}
210 			setproctitle("%s: %s", CurHostName, inp);
211 			if (strcasecmp(p, MyHostName) == 0)
212 			{
213 				/*
214 				**  Didn't know about alias or MX,
215 				**  or connected to an echo server
216 				*/
217 
218 				message("553 %s config error: mail loops back to myself",
219 					MyHostName);
220 				break;
221 			}
222 			if (strcasecmp(p, RealHostName) != 0)
223 			{
224 				char hostbuf[MAXNAME];
225 
226 				(void) sprintf(hostbuf, "%s (%s)", p, RealHostName);
227 				sendinghost = newstr(hostbuf);
228 			}
229 			else
230 				sendinghost = newstr(p);
231 
232 			/* send ext. message -- old systems must ignore */
233 			message("250-%s Hello %s, pleased to meet you",
234 				MyHostName, sendinghost);
235 			if (!bitset(PRIV_NOEXPN, PrivacyFlags))
236 				message("250-EXPN");
237 			message("250 HELP");
238 			gothello = TRUE;
239 			break;
240 
241 		  case CMDMAIL:		/* mail -- designate sender */
242 			SmtpPhase = "MAIL";
243 
244 			/* force a sending host even if no HELO given */
245 			if (sendinghost == NULL && macvalue('s', e) == NULL)
246 				sendinghost = RealHostName;
247 
248 			/* check for validity of this command */
249 			if (!gothello && bitset(PRIV_NEEDMAILHELO, PrivacyFlags))
250 			{
251 				message("503 Polite people say HELO first");
252 				break;
253 			}
254 			if (gotmail)
255 			{
256 				message("503 Sender already specified");
257 				break;
258 			}
259 			if (InChild)
260 			{
261 				errno = 0;
262 				syserr("503 Nested MAIL command: MAIL %s", p);
263 				finis();
264 			}
265 			if (!enoughspace())
266 			{
267 				message("452 Insufficient disk space; try again later");
268 				break;
269 			}
270 
271 			/* fork a subprocess to process this command */
272 			if (runinchild("SMTP-MAIL", e) > 0)
273 				break;
274 			if (sendinghost != NULL)
275 				define('s', sendinghost, e);
276 			if (protocol == NULL)
277 				protocol = "SMTP";
278 			define('r', protocol, e);
279 			initsys(e);
280 			setproctitle("%s %s: %s", e->e_id, CurHostName, inp);
281 
282 			/* child -- go do the processing */
283 			p = skipword(p, "from");
284 			if (p == NULL)
285 				break;
286 			if (setjmp(TopFrame) > 0)
287 			{
288 				/* this failed -- undo work */
289 				if (InChild)
290 					finis();
291 				break;
292 			}
293 			QuickAbort = TRUE;
294 			setsender(p, e);
295 			message("250 Sender ok");
296 			gotmail = TRUE;
297 			break;
298 
299 		  case CMDRCPT:		/* rcpt -- designate recipient */
300 			SmtpPhase = "RCPT";
301 			setproctitle("%s %s: %s", e->e_id, CurHostName, inp);
302 			if (setjmp(TopFrame) > 0)
303 			{
304 				e->e_flags &= ~EF_FATALERRS;
305 				break;
306 			}
307 			QuickAbort = TRUE;
308 			LogUsrErrs = TRUE;
309 
310 			/* optimization -- if queueing, don't expand aliases */
311 			if (SendMode == SM_QUEUE)
312 				e->e_flags |= EF_VRFYONLY;
313 
314 			p = skipword(p, "to");
315 			if (p == NULL)
316 				break;
317 			a = parseaddr(p, (ADDRESS *) NULL, 1, ' ', e);
318 			if (a == NULL)
319 				break;
320 			a->q_flags |= QPRIMARY;
321 			a = recipient(a, &e->e_sendqueue, e);
322 			if (Errors != 0)
323 				break;
324 
325 			/* no errors during parsing, but might be a duplicate */
326 			e->e_to = p;
327 			if (!bitset(QBADADDR, a->q_flags))
328 				message("250 Recipient ok");
329 			else
330 			{
331 				/* punt -- should keep message in ADDRESS.... */
332 				message("550 Addressee unknown");
333 			}
334 			e->e_to = NULL;
335 			break;
336 
337 		  case CMDDATA:		/* data -- text of mail */
338 			SmtpPhase = "DATA";
339 			if (!gotmail)
340 			{
341 				message("503 Need MAIL command");
342 				break;
343 			}
344 			else if (e->e_nrcpts <= 0)
345 			{
346 				message("503 Need RCPT (recipient)");
347 				break;
348 			}
349 
350 			/* collect the text of the message */
351 			SmtpPhase = "collect";
352 			setproctitle("%s %s: %s", e->e_id, CurHostName, inp);
353 			collect(TRUE, e);
354 			if (Errors != 0)
355 				break;
356 
357 			/*
358 			**  Arrange to send to everyone.
359 			**	If sending to multiple people, mail back
360 			**		errors rather than reporting directly.
361 			**	In any case, don't mail back errors for
362 			**		anything that has happened up to
363 			**		now (the other end will do this).
364 			**	Truncate our transcript -- the mail has gotten
365 			**		to us successfully, and if we have
366 			**		to mail this back, it will be easier
367 			**		on the reader.
368 			**	Then send to everyone.
369 			**	Finally give a reply code.  If an error has
370 			**		already been given, don't mail a
371 			**		message back.
372 			**	We goose error returns by clearing error bit.
373 			*/
374 
375 			SmtpPhase = "delivery";
376 			if (e->e_nrcpts != 1)
377 			{
378 				HoldErrs = TRUE;
379 				ErrorMode = EM_MAIL;
380 			}
381 			e->e_flags &= ~EF_FATALERRS;
382 			e->e_xfp = freopen(queuename(e, 'x'), "w", e->e_xfp);
383 
384 			/* send to all recipients */
385 			sendall(e, SM_DEFAULT);
386 			e->e_to = NULL;
387 
388 			/* save statistics */
389 			markstats(e, (ADDRESS *) NULL);
390 
391 			/* issue success if appropriate and reset */
392 			if (Errors == 0 || HoldErrs)
393 				message("250 Ok");
394 			else
395 				e->e_flags &= ~EF_FATALERRS;
396 
397 			/* if in a child, pop back to our parent */
398 			if (InChild)
399 				finis();
400 
401 			/* clean up a bit */
402 			gotmail = FALSE;
403 			dropenvelope(e);
404 			CurEnv = e = newenvelope(e, CurEnv);
405 			e->e_flags = BlankEnvelope.e_flags;
406 			break;
407 
408 		  case CMDRSET:		/* rset -- reset state */
409 			message("250 Reset state");
410 			if (InChild)
411 				finis();
412 
413 			/* clean up a bit */
414 			gotmail = FALSE;
415 			dropenvelope(e);
416 			CurEnv = e = newenvelope(e, CurEnv);
417 			break;
418 
419 		  case CMDVRFY:		/* vrfy -- verify address */
420 		  case CMDEXPN:		/* expn -- expand address */
421 			vrfy = c->cmdcode == CMDVRFY;
422 			if (bitset(vrfy ? PRIV_NOVRFY : PRIV_NOEXPN,
423 						PrivacyFlags))
424 			{
425 				message("502 That's none of your business");
426 				break;
427 			}
428 			else if (!gothello &&
429 				 bitset(vrfy ? PRIV_NEEDVRFYHELO : PRIV_NEEDEXPNHELO,
430 						PrivacyFlags))
431 			{
432 				message("503 I demand that you introduce yourself first");
433 				break;
434 			}
435 			if (runinchild(vrfy ? "SMTP-VRFY" : "SMTP-EXPN", e) > 0)
436 				break;
437 			setproctitle("%s: %s", CurHostName, inp);
438 #ifdef LOG
439 			if (LogLevel > 5)
440 				syslog(LOG_INFO, "%s: %s", CurHostName, inp);
441 #endif
442 			vrfyqueue = NULL;
443 			QuickAbort = TRUE;
444 			if (vrfy)
445 				e->e_flags |= EF_VRFYONLY;
446 			(void) sendtolist(p, (ADDRESS *) NULL, &vrfyqueue, e);
447 			if (Errors != 0)
448 			{
449 				if (InChild)
450 					finis();
451 				break;
452 			}
453 			while (vrfyqueue != NULL)
454 			{
455 				register ADDRESS *a = vrfyqueue->q_next;
456 				char *code;
457 
458 				while (a != NULL && bitset(QDONTSEND|QBADADDR, a->q_flags))
459 					a = a->q_next;
460 
461 				if (!bitset(QDONTSEND|QBADADDR, vrfyqueue->q_flags))
462 					printvrfyaddr(vrfyqueue, a == NULL);
463 				else if (a == NULL)
464 					message("554 Self destructive alias loop");
465 				vrfyqueue = a;
466 			}
467 			if (InChild)
468 				finis();
469 			break;
470 
471 		  case CMDHELP:		/* help -- give user info */
472 			help(p);
473 			break;
474 
475 		  case CMDNOOP:		/* noop -- do nothing */
476 			message("200 OK");
477 			break;
478 
479 		  case CMDQUIT:		/* quit -- leave mail */
480 			message("221 %s closing connection", MyHostName);
481 			if (InChild)
482 				ExitStat = EX_QUIT;
483 			finis();
484 
485 		  case CMDVERB:		/* set verbose mode */
486 			Verbose = TRUE;
487 			SendMode = SM_DELIVER;
488 			message("200 Verbose mode");
489 			break;
490 
491 		  case CMDONEX:		/* doing one transaction only */
492 			OneXact = TRUE;
493 			message("200 Only one transaction");
494 			break;
495 
496 # ifdef SMTPDEBUG
497 		  case CMDDBGQSHOW:	/* show queues */
498 			printf("Send Queue=");
499 			printaddr(e->e_sendqueue, TRUE);
500 			break;
501 
502 		  case CMDDBGDEBUG:	/* set debug mode */
503 			tTsetup(tTdvect, sizeof tTdvect, "0-99.1");
504 			tTflag(p);
505 			message("200 Debug set");
506 			break;
507 
508 # else /* not SMTPDEBUG */
509 
510 		  case CMDDBGQSHOW:	/* show queues */
511 		  case CMDDBGDEBUG:	/* set debug mode */
512 # ifdef LOG
513 			if (LogLevel > 0)
514 				syslog(LOG_NOTICE,
515 				    "\"%s\" command from %s (%s)",
516 				    c->cmdname, RealHostName,
517 				    inet_ntoa(RealHostAddr.sin_addr));
518 # endif
519 			/* FALL THROUGH */
520 # endif /* SMTPDEBUG */
521 
522 		  case CMDERROR:	/* unknown command */
523 			message("500 Command unrecognized");
524 			break;
525 
526 		  default:
527 			errno = 0;
528 			syserr("500 smtp: unknown code %d", c->cmdcode);
529 			break;
530 		}
531 	}
532 }
533 /*
534 **  SKIPWORD -- skip a fixed word.
535 **
536 **	Parameters:
537 **		p -- place to start looking.
538 **		w -- word to skip.
539 **
540 **	Returns:
541 **		p following w.
542 **		NULL on error.
543 **
544 **	Side Effects:
545 **		clobbers the p data area.
546 */
547 
548 static char *
549 skipword(p, w)
550 	register char *p;
551 	char *w;
552 {
553 	register char *q;
554 
555 	/* find beginning of word */
556 	while (isascii(*p) && isspace(*p))
557 		p++;
558 	q = p;
559 
560 	/* find end of word */
561 	while (*p != '\0' && *p != ':' && !(isascii(*p) && isspace(*p)))
562 		p++;
563 	while (isascii(*p) && isspace(*p))
564 		*p++ = '\0';
565 	if (*p != ':')
566 	{
567 	  syntax:
568 		message("501 Syntax error");
569 		Errors++;
570 		return (NULL);
571 	}
572 	*p++ = '\0';
573 	while (isascii(*p) && isspace(*p))
574 		p++;
575 
576 	/* see if the input word matches desired word */
577 	if (strcasecmp(q, w))
578 		goto syntax;
579 
580 	return (p);
581 }
582 /*
583 **  PRINTVRFYADDR -- print an entry in the verify queue
584 **
585 **	Parameters:
586 **		a -- the address to print
587 **		last -- set if this is the last one.
588 **
589 **	Returns:
590 **		none.
591 **
592 **	Side Effects:
593 **		Prints the appropriate 250 codes.
594 */
595 
596 printvrfyaddr(a, last)
597 	register ADDRESS *a;
598 	bool last;
599 {
600 	char fmtbuf[20];
601 
602 	strcpy(fmtbuf, "250");
603 	fmtbuf[3] = last ? ' ' : '-';
604 
605 	if (strchr(a->q_paddr, '<') != NULL)
606 		strcpy(&fmtbuf[4], "%s");
607 	else if (a->q_fullname == NULL)
608 		strcpy(&fmtbuf[4], "<%s>");
609 	else
610 	{
611 		strcpy(&fmtbuf[4], "%s <%s>");
612 		message(fmtbuf, a->q_fullname, a->q_paddr);
613 		return;
614 	}
615 	message(fmtbuf, a->q_paddr);
616 }
617 /*
618 **  HELP -- implement the HELP command.
619 **
620 **	Parameters:
621 **		topic -- the topic we want help for.
622 **
623 **	Returns:
624 **		none.
625 **
626 **	Side Effects:
627 **		outputs the help file to message output.
628 */
629 
630 help(topic)
631 	char *topic;
632 {
633 	register FILE *hf;
634 	int len;
635 	char buf[MAXLINE];
636 	bool noinfo;
637 
638 	if (HelpFile == NULL || (hf = fopen(HelpFile, "r")) == NULL)
639 	{
640 		/* no help */
641 		errno = 0;
642 		message("502 HELP not implemented");
643 		return;
644 	}
645 
646 	if (topic == NULL || *topic == '\0')
647 		topic = "smtp";
648 	else
649 		makelower(topic);
650 
651 	len = strlen(topic);
652 	noinfo = TRUE;
653 
654 	while (fgets(buf, sizeof buf, hf) != NULL)
655 	{
656 		if (strncmp(buf, topic, len) == 0)
657 		{
658 			register char *p;
659 
660 			p = strchr(buf, '\t');
661 			if (p == NULL)
662 				p = buf;
663 			else
664 				p++;
665 			fixcrlf(p, TRUE);
666 			message("214-%s", p);
667 			noinfo = FALSE;
668 		}
669 	}
670 
671 	if (noinfo)
672 		message("504 HELP topic unknown");
673 	else
674 		message("214 End of HELP info");
675 	(void) fclose(hf);
676 }
677 /*
678 **  RUNINCHILD -- return twice -- once in the child, then in the parent again
679 **
680 **	Parameters:
681 **		label -- a string used in error messages
682 **
683 **	Returns:
684 **		zero in the child
685 **		one in the parent
686 **
687 **	Side Effects:
688 **		none.
689 */
690 
691 runinchild(label, e)
692 	char *label;
693 	register ENVELOPE *e;
694 {
695 	int childpid;
696 
697 	if (!OneXact)
698 	{
699 		childpid = dofork();
700 		if (childpid < 0)
701 		{
702 			syserr("%s: cannot fork", label);
703 			return (1);
704 		}
705 		if (childpid > 0)
706 		{
707 			auto int st;
708 
709 			/* parent -- wait for child to complete */
710 			st = waitfor(childpid);
711 			if (st == -1)
712 				syserr("%s: lost child", label);
713 
714 			/* if we exited on a QUIT command, complete the process */
715 			if (st == (EX_QUIT << 8))
716 				finis();
717 
718 			return (1);
719 		}
720 		else
721 		{
722 			/* child */
723 			InChild = TRUE;
724 			QuickAbort = FALSE;
725 			clearenvelope(e, FALSE);
726 		}
727 	}
728 
729 	/* open alias database */
730 	initaliases(AliasFile, FALSE, e);
731 
732 	return (0);
733 }
734 
735 # endif /* SMTP */
736