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From: abe@mace.cc.purdue.edu (Vic Abell)
Newsgroups: comp.protocols.tcp-ip
Subject: Re: Odd FTP Problem
Summary: Another cause of data connection failure
Message-ID: <1861@mace.cc.purdue.edu>
Date: 27 Feb 89 15:41:21 GMT
References: <890227123252.420278@DOCKMASTER.ARPA>
Organization: Purdue University
Lines: 11

There is another BSD ftpd problem in the very latest post-worm release that
can cause data connection failure.  The connection failure occurs when there
are two, incoming ftpd calls from the same remote peer.  If the two, receiving
ftpd processes both try to open a data connection at the same time, one can
fail with an EADDRINUSE error.  We have fixed this problem locally by adding
a retry loop in ftpd.c's getdatasock() function.

The released ftpd lacks this loop.  It also may be reporting the cause of
data connection failures improperly when they result from an error in the
bind() call within getdatasock().  There are several function calls between
the bind() and the reply() call that can change the value of errno.