Re: Socket and Protocol error in error_log file (fwd)

[Randy Terbush <ra...@zyzzyva.com>]

Very interesting. I'm willing to bet that this is the problem we
have seen in the past on Unixware. I've been led several times to
this part of the code, but have not been clueful enough to figure
out a problem.


> Comments?
> 
> (it would need to be wrapped in a whack of ifdefs, since not all platforms
> have EPROTO, etc.)
> 
> ---------- Forwarded message ----------
> Date: Fri, 17 Jan 1997 10:47:30 -0700
> From: Marc Slemko <ma...@znep.com>
> To: marcs@znep.com
> Subject: VERY URGENT!!!!! Socket and Protocol error in error_log file
> 
> 
> >Path: pulp.ucs.ualberta.ca!rover.ucs.ualberta.ca!news.bc.net!arclight.uoregon.edu!news.bbnplanet.com!su-news-hub1.bbnplanet.com!venus.sun.com!news2me.EBay.Sun.COM!engnews2.Eng.Sun.COM!engnews1.Eng.Sun.COM!usenet
> >From: Mukesh Kacker <mu...@eng.sun.com>
> >Newsgroups: comp.infosystems.www.servers.unix
> >Subject: Re: VERY URGENT!!!!! Socket and Protocol error in error_log file
> >Date: 17 Jan 1997 06:26:45 -0800
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> 
> "cythere" <ch...@cythere.com> writes:
> 
> 
> The "protocol error" (errno EPROTO in Unix) failure for accept() occurs
> when an incoming connection gets aborted before the accept() completes.
> 
> The exact technical debate on this issue is convoluted (no long flames
> or technical discussions please :-)) but here is a brief summary.
> When an incoming connection is aborted, BSD derived platforms the accept()
> does not return an error. For web servers with high connection rates this
> works fine but in some fringe cases, it may cause a select() to indicate
> an incoming connection but a process/thread hanging in accept() forever which
> is unacceptable. So some platforms return this EPROTO error in this
> situation. This is admittedly a confusing error code and in future platform
> vendors will be returning an ECONNABORTED error for this case (and not
> EPROTO).
> 
> This problems happens on some Solaris 2.x (and I have heard it happens on
> Unixware based platforms) etc. In Solaris 2.5.1 with Internet Server Supplement
> - ISS 1.0 patch applied, the error would be ECONNABORTED (and not EPROTO).
> 
> For Web servers, the right thing to do is to ignore this error (as they
> do EINTR) and not log it and retry the accept() call.
> I have tried through friends/contacts in Apache development
> to get this fixed in the past, but apparently not hard enough :-)
> 
> I am not sure what the latest Apache code looks like, but the Apache 1.1.1
> does something like this in http_main.c
> ---
> 	do
> 		csd = accept()
> 	while (csd == -1 && errno == EINTR);
> 	if ( csd != -1) break;
> 	log_unixerr();
> 
> -- 
> 
> One portable way to write this code to work on all platforms (present
> and future would be:
> 
> ---
> 	do
> 		csd = accept()
> 	while (csd == -1 &&
> 		(errno == EINTR ||  /* interrupted call - retry */
> 		 errno == ECONNABORTED || /* aborted connection - retry */
> 		 errno == EPROTO) /* aborted connection - retry */
> 		);
> 
> ---
> For efficiency reasons, some should study the frequency of the three
> error codes above and check them in that order to minimize compares.
> 
> If you have friends and influence in the Apache development team, please
> pass this on so that it gets fixed :-)
> 
> ----------------------------------------------------------------------
> Mukesh Kacker                   | Football incorporates the two worst
> Sun Microsystems Inc (SunSoft)  | characteristics of American society.
> mukesh.kacker@eng.sun.com       | Violence punctuated by committee meetings.
> Internet Engineering            |                      -- George Will