Re: Changes to PCBPORTHASH wrt TCP, review needed

From: Mike Silbersack (silby_at_silby.com)
Date: 10/28/03

  • Next message: Bruce M Simpson: "Re: Changes to PCBPORTHASH wrt TCP, review needed" 
    Date: Tue, 28 Oct 2003 13:23:32 -0600 (CST)
To: Bruce M Simpson <bms@spc.org>

    On Tue, 28 Oct 2003, Bruce M Simpson wrote:

    > We discussed on IRC that this problem of ephemeral port hash mapping may also
    > affect udp PCBs, and that it may be having undesirable effects with multiple
    > concurrent media streams, as RTP/RTCP is a heavy udp socket consumer in a
    > large installation, and has specific requirements for binding consecutive
    > odd/even port pairs (more details in RFC 3550 for those who care).
    >
    > I will test the patch shortly. I have looked over it and can't find any
    > immediate problems with it, but further digestion on my part is required.
    >
    > BMS

    Bleh, I found a problem with my suggested change. Suppose that a program
    works as follows:

    1. bind (to an ephemeral port)
    2. connect

    It's very possible that bind will return a port which can't be used
    because it's already in use for that destination lport-laddr-fport-faddr
    tuple, so the connect will fail with EADDRINUSE.

    So, it looks like I can't solve this so simply... looks like I'll have to
    have the port lookup do IP comparisons as well.

    Mike "Silby" Silbersack
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