mod_proxy/304: multiple-homed Web hosts - con refused to first IP doesn't fall through to second

[Michael Pelletier <mi...@comshare.com>]

>Number:         304
>Category:       mod_proxy
>Synopsis:       multiple-homed Web hosts - con refused to first IP doesn't fall through to second
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    apache (Apache HTTP Project)
>State:          open
>Class:          sw-bug
>Submitter-Id:   apache
>Arrival-Date:   Wed Apr  2 09:50:01 1997
>Originator:     mikep@comshare.com
>Organization:
apache
>Release:        1.2b7
>Environment:
BSD/OS 2.1 pl27 on P-133, bundled GCC 2.7.2
>Description:
I've run into this problem today at www.pcquote.com.  That
server address has three different IP addresses assigned to it, presumably
on different backup/mirror servers.

I began to get immediate "Could not connect to remote machine"
proxy errors this morning while trying to connect to this site, and
when I telnetted to the system by hand, I got a connection
refused message to the first IP address, but my telnet client immediately
connected to the second IP address and established a connection.
Also, when I hit reload a couple of times on this page, it eventually
makes the connection -- presumably due to a round-robin cycling of the
IP addresses.

It appears that Apache proxy is returning the immediate proxy error when
it gets the connection refused on the first IP address, and doesn't
proceed to try the alternates.

This problem was first noticed by people connecting extensively to
Microsoft web server sites, which are prone to busy timeouts and the
like.

Drop me an e-mail when you get this, and in the meantime I'll see if
I can whip up a patch for the problem.

	-Mike Pelletier.
>How-To-Repeat:
Assuming www.pcquote.com is still having a connection-refused problem when
you get this, try there through the proxy.  Also try www.microsoft.com during
a busy part of the day.
>Fix:
Haven't looked at the code yet, I'll let you know as soon as I have an
e-mail address for you
>Audit-Trail:
>Unformatted: