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[lwip-devel] [patch #7906] Broadcast handling and UDP port binding for m

From: Nick van IJzendoorn
Subject: [lwip-devel] [patch #7906] Broadcast handling and UDP port binding for multiple phy in same subnet
Date: Fri, 21 Dec 2012 10:47:53 +0000
User-agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.11 (KHTML, like Gecko) Chrome/23.0.1271.97 Safari/537.11


                 Summary: Broadcast handling and UDP port binding for multiple
phy in same subnet
                 Project: lwIP - A Lightweight TCP/IP stack
            Submitted by: dipswitch_
            Submitted on: Fri 21 Dec 2012 10:47:51 AM GMT
                Category: None
                Priority: 5 - Normal
                  Status: None
                 Privacy: Public
             Assigned to: None
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
         Planned Release: None



Currently we are working on a device which has two interfaces in the same

We noticed that if an UDP broadcast message was received while both
connections are alive to the same subnet the broadcast will be routed to the
first interface and never to the socket where the socket was bound on.
This would be wrong in my opinion since if a socket is bound to a specific
address it should not receive the message of the other interface.

Another problem we noticed, was that when you bind the socket to a specific
address, the ip_route function would not take this into account, which results
in selecting of the first available route for the given packet. Later in the
function udp_sendto_if_chksum the packet would be dropped since the source
address would not match the interface address.

Hereby I send the patch written for LwIP v1.4.0. I don't know if it would
break any other functionality but I think this should be the right way the
packets should be handled.

Kind regards,


File Attachments:

Date: Fri 21 Dec 2012 10:47:51 AM GMT  Name: dual-phy-same-subnet.patch  Size:
1kB   By: dipswitch_



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