cc as DHCP relay agent

[wlanmac]

Committed to svn. If you could test it out, I would appreciate it.

David


On Fri, 2009-03-13 at 10:18 +0100, Thomas Liske wrote:
> Hi,
> 
> I think there is an issue with DHCP relay in coova-chilli. Cc always 
> listens on port 68 for replies from the DHCP server when acting as a 
> DHCP relay (line 592):
> 
> $ cat -n src/dhcp.c | grep -C 5 'htons(68)'
>     587
>     588      if (fd > 0) {
>     589        memset(&addr, 0, sizeof(addr));
>     590        addr.sin_family = AF_INET;
>     591        addr.sin_addr.s_addr = dhcp->uamlisten.s_addr;
>     592        addr.sin_port = htons(68);
>     593
>     594        if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, 
> sizeof(on)) < 0) {
>     595          log_err(errno, "Can't set reuse option");
>     596        }
>     597
> 
> This does not work with the (recent) ISC DHCP Daemon v3. The dhcpd 
> always replies to port 67 ignoring the port number seen in the request 
> packet from the DHCP relay agent.
> 
> There is a working draft stating about the port usage with relay agents:
> 
> ====[http://tools.ietf.org/id/draft-ietf-dhc-implementation-02.txt]====
> 4.7.2 Relay Agent Port Usage
>    Relay agents should use port 67 as the source port number.  Relay
>    agents always listen on port 67, but port 68 has sometimes been used
>    as the source port number probably because it was copied from the
>    source port of the incoming packet.
> 
>    Cable modem vendors would like to install filters blocking outgoing
>    packets with source port 67.
> 
>    RECOMMENDATIONS:
>      O  Relay agents MUST use 67 as their source port number.
>      O  Relay agents MUST NOT forward packets with non-zero giaddr
>         unless the source port number on the packet is 67.
> ====[http://tools.ietf.org/id/draft-ietf-dhc-implementation-02.txt]====
> 
> IMHO cc should listen on port 67/udp when acting as DHCP relay agent.
> 
> 
> 	Thomas
> 
> 
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