problems with udp header compression

I think I have stumbled across a bug in the udp header compression or possibly in a higher layer of the network stack.

If I send a UDP message using a RAW socket[0] the src and dest port numbers get corrupted on 802.15.4 devices. This does not occur on ethernet.

If I print out the udp source and destination ports in compress_udp_header they are incorrect. The function udp_hdr is not pointing at the udp header but actually the ip6 header.

If I send a UDP message using a normal UDP socket I do not have this problem.

Any ideas?

Simon

[0] - socket(AF_INET6, SOCK_RAW, IPPROTO_RAW);

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This appears to be because if you use a RAW socket with IPPROTO_RAW the ipv6 stack passes it straight through and the skb transport_header, network_header offset are not set.

Putting the following at the top of compress_udp_header fixes the problem but I am not sure it is safe.

if (skb->transport_header == skb->network_header){
        skb_set_transport_header(skb,sizeof(struct ipv6hdr));
    }

Hi Simon,

Quoted 10 lines · Simon Vincent

This appears to be because if you use a RAW socket with IPPROTO_RAW the ipv6 stack passes it straight through and the skb transport_header, network_header offset are not set.

Putting the following at the top of compress_udp_header fixes the problem but I am not sure it is safe.

if (skb->transport_header == skb->network_header){
         skb_set_transport_header(skb,sizeof(struct ipv6hdr));
     }

I see, this could make trouble for IPV6 RAW sockets. Can you please send a patch for this and cc linux-bluetooth and linux-wpan. Also add some comment why we do this is here, because the RAW socket issue.

Or just send it as RFC (means replace the PATCH into RFC in the subject). Then we can talk about a better solution if this isn't a perfect solution.

Also remove the unnecessary brackets -> checkpatch should show an error because this.

- Alex
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I will send a patch. I have done lots of testing and it seems fine. Do you want the patch based on bluetooth-next?