netdev - How to find an available TCP port

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Message-ID: <CADHp1Nzgjs5OGXWhs-zy6LZ2wsbspRAc+EW4_J3EsUjOOPCxTA@mail.gmail.com>
Date:	Tue, 2 Apr 2013 17:25:58 +0200
From:	Teto <mattator@...il.com>
To:	netdev@...r.kernel.org
Subject: How to find an available TCP port

Hi,

I would like to do deterministic port-based load balancing, that is
choosing a free port number N so that N % K = X while knowing K and X.

Since I am patching a specific implementation, I would like to check
the availibility of the port without having to check bind() return
value.

I believe the function tcp_lport_inuse ( in this file
http://www.cab.u-szeged.hu/linux/kernel/linux/net/ipv4/tcp.c.html)
does what I wish. I would like to call it from another file but it is
static. So here are my questions:
1st/ Is that the correct function ?
2/ How to use it in another src file ? or do you have any other workaround ?

Sorry if that's too noobish a question, I am not used to kernel
development (yet). I f that's the case redirect me to the proper
mailing list.

Best regards
Matt
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