[lwip-devel] [bug #35927] missing refragmentaion in ip_forward

[Malte Langermann]

URL:
  <http://savannah.nongnu.org/bugs/?35927>

                 Summary: missing refragmentaion in ip_forward
                 Project: lwIP - A Lightweight TCP/IP stack
            Submitted by: gagarin
            Submitted on: Mi 21 Mär 2012 08:46:49 GMT
                Category: IPv4
                Severity: 3 - Normal
              Item Group: Faulty Behaviour
                  Status: None
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
         Planned Release: 
            lwIP version: 1.4.0

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Details:

In ip_forward no ip refragmentation is done, so that if the mtu of the target
Interface is smaller than the forwarding packet, the packet will be dropped.
The code should be changed form this:

core/ipv4/ip.c:
ip_forward:
266    PERF_STOP("ip_forward");
267    /* transmit pbuf on chosen interface */
268    netif->output(netif, p, &current_iphdr_dest);
269    return;
270    return_noroute:
271    snmp_inc_ipoutnoroutes();
272  }
273

to something like this (copied from ip_output in the same file)

ip_output:
774  #if IP_FRAG
775    /* don't fragment if interface has mtu set to 0 [loopif] */
776    if (netif->mtu && (p->tot_len > netif->mtu)) {
777      return ip_frag(p, netif, dest);
778    }
779  #endif /* IP_FRAG */
780
781    LWIP_DEBUGF(IP_DEBUG, ("netif->output()"));
782    return netif->output(netif, p, dest);
783  }






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