From owner-freebsd-questions  Fri Nov 10 19:57: 6 2000
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To: j mckitrick <jcm@FreeBSD-uk.eu.org>
Cc: freebsd-questions@FreeBSD.ORG
Subject: Re: programming a file transfer 
In-Reply-To: Your message of "Fri, 10 Nov 2000 19:18:44 GMT."
             <20001110191844.A20862@dogma.freebsd-uk.eu.org> 
Date: Fri, 10 Nov 2000 19:55:46 -0800
From: Sriranga Veeraraghavan <ranga@CSUA.Berkeley.EDU>
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Hi,

Sounds like you probably want need to use setsockopt(2), specifically
the SO_REUSEADDR.

This option allows a process to bind to a well-known port even if
other connections already use that port. For more info see Stevens,
Unix Network Programming Volume 1 2nd edition, pg 194.

Some people like SO_LINGER better than SO_REUSEADDR, but Stevens says
to use not to use SO_LINGER for various reasons (pg 187).

After you create the socket via socket(2), you should probably call
setsockopt similar to the following to get the desired behavior:

  int flags = 1;
  ...
  if (setsockopt(sock_listen, SOL_SOCKET, SO_REUSEADDR, 
                 (void *)&flags, sizeof(flags)) < 0) {
    close(sock_listen);
    perror("Error");
  }

HTH,

----ranga




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