sendmail puzzles

[Satz%sri-tsc at sri-unix.UUCP]

From:  Greg Satz <Satz at sri-tsc>


I have just spent the last few days getting to know sendmail on a
pdp-11/44 running 2.9bsd.  There were some real fun problems along the
way that some of you may not be interested in discovering yourselves.

I rewrote the 4.1a_daemon.c file that is distributed so it would take
advantage of the 2.9/4.1b library routines (the original was just plain
disgusting).  If anyone is interested in a copy, drop me a note.

I found a nasty problem that may plague sites which run out of mbufs:

daemon.c {4.2}

makeconnection(host, port, outfile, infile)
...
	s = socket(AF_INET, SOCK_STREAM, 0, 0);
	if (s < 0)
	{
		syserr("makeconnection: no socket");
		goto failure;
	}
...
		/* failure, decide if temporary or not */
	failure:
		switch (errno)

When the socket call fails (on pdp-11/44s, this happens frequently),
syserr is called to send an error message to syslog.  Unfortunately, it
clears errno in the process thus preventing the mail from being requeued.
My fix:

	s = socket(AF_INET, SOCK_STREAM, 0, 0);
	if (s < 0)
	{
		int saverr = errno;

		syserr("makeconnection: no socket");
		errno = saverr;
		goto failure;
	}

Here are some others that mustn't cause any problems for Vaxen, but
prevent sendmail from being very useful on pdp-11s.

We have some large mailing lists which caused sendmail to dump core.
We tried increasing this even larger, but then sendmail exhausts its
stack space.

*** conf.h_	Sat Nov 19 16:23:35 1983
--- conf.h	Tue Mar  6 18:07:00 1984
***************
*** 11,17
  **	There shouldn't be much need to change these....
  */
  
! # define MAXLINE	256		/* max line length */
  # define MAXNAME	128		/* max length of a name */
  # define MAXFIELD	2500		/* max total length of a hdr field */
  # define MAXPV		40		/* max # of parms to mailers */

--- 11,17 -----
  **	There shouldn't be much need to change these....
  */
  
! # define MAXLINE	512		/* max line length */
  # define MAXNAME	128		/* max length of a name */
  # define MAXFIELD	2500		/* max total length of a hdr field */
  # define MAXPV		40		/* max # of parms to mailers */

This is evidently a bug that never caused anyone any problems. I was
in paranoia mode, so I did this.

*** clock.c_	Sat Nov 19 16:25:30 1983
--- clock.c	Tue Feb 28 16:21:37 1984
***************
*** 142,148
  	while ((ev = EventQueue) != NULL &&
  	       (ev->ev_time <= now || ev->ev_pid != getpid()))
  	{
! 		int (*f)(), a;
  
  		/* process the event on the top of the queue */
  		ev = EventQueue;

--- 142,148 -----
  	while ((ev = EventQueue) != NULL &&
  	       (ev->ev_time <= now || ev->ev_pid != getpid()))
  	{
! 		int (*f)(), a, pid;
  
  		/* process the event on the top of the queue */
  		ev = EventQueue;
***************
*** 157,162
  		(void) signal(SIGALRM, tick);
  		f = ev->ev_func;
  		a = ev->ev_arg;
  		free((char *) ev);
  		if (ev->ev_pid != getpid())
  			continue;

--- 157,163 -----
  		(void) signal(SIGALRM, tick);
  		f = ev->ev_func;
  		a = ev->ev_arg;
+ 		pid = ev->ev_pid;
  		free((char *) ev);
  		if (pid != getpid())
  			continue;
***************
*** 158,164
  		f = ev->ev_func;
  		a = ev->ev_arg;
  		free((char *) ev);
! 		if (ev->ev_pid != getpid())
  			continue;
  		if (EventQueue != NULL)
  		{

--- 159,165 -----
  		a = ev->ev_arg;
  		pid = ev->ev_pid;
  		free((char *) ev);
! 		if (pid != getpid())
  			continue;
  		if (EventQueue != NULL)
  		{

Lint found this one.

*** srvrsmtp.c_	Sat Nov 19 16:25:35 1983
--- srvrsmtp.c	Wed Feb 29 14:42:58 1984
***************
*** 228,234
  			p = skipword(p, "to");
  			if (p == NULL)
  				break;
! 			a = parseaddr(p, (ADDRESS *) NULL, 1);
  			if (a == NULL)
  				break;
  			a = recipient(a, &CurEnv->e_sendqueue);

--- 228,234 -----
  			p = skipword(p, "to");
  			if (p == NULL)
  				break;
! 			a = parseaddr(p, (ADDRESS *) NULL, 1, '\0');
  			if (a == NULL)
  				break;
  			a = recipient(a, &CurEnv->e_sendqueue);

This was a real problem; connections were never timing out. Lint
found the others.

*** usersmtp.c_	Sat Nov 19 16:25:15 1983
--- usersmtp.c	Wed Mar  7 22:27:15 1984
***************
*** 99,105
  
  	if (setjmp(CtxGreeting) != 0)
  		goto tempfail;
! 	gte = setevent(300, greettimeout, 0);
  	r = reply(m);
  	clrevent(gte);
  	if (r < 0 || REPLYTYPE(r) != 2)

--- 99,106 -----
  
  	if (setjmp(CtxGreeting) != 0) {
  		goto tempfail;
! 	}
! 	gte = setevent((time_t) 300, greettimeout, 0);
  	r = reply(m);
  	clrevent(gte);
  	if (r < 0 || REPLYTYPE(r) != 2)
***************
*** 169,175
  
  	/* signal a temporary failure */
    tempfail:
! 	smtpquit(m);
  	return (EX_TEMPFAIL);
  
  	/* signal service unavailable */

--- 170,176 -----
  
  	/* signal a temporary failure */
    tempfail:
! 	smtpquit(pvp[0], m);
  	return (EX_TEMPFAIL);
  
  	/* signal service unavailable */
***************
*** 174,180
  
  	/* signal service unavailable */
    unavailable:
! 	smtpquit(m);
  	return (EX_UNAVAILABLE);
  }
  

--- 175,181 -----
  
  	/* signal service unavailable */
    unavailable:
! 	smtpquit(pvp[0], m);
  	return (EX_UNAVAILABLE);
  }
  
Another timeout problem.

*** util.c_	Sat Nov 19 16:25:44 1983
--- util.c	Thu Feb 23 18:03:01 1984
***************
*** 646,652
  			syserr("sfgets: timeout on read (mailer may be hung)");
  			return (NULL);
  		}
! 		ev = setevent(ReadTimeout, readtimeout, 0);
  	}
  
  	/* try to read */

--- 646,652 -----
  			syserr("sfgets: timeout on read (mailer may be hung)");
  			return (NULL);
  		}
! 		ev = setevent((time_t) ReadTimeout, readtimeout, 0);
  	}
  
  	/* try to read */