Re: [lwip-devel] RFC3542 ICMPv6 Checksum Computation for Raw Sockets

[Grant Erickson]

On Dec 19, 2012, at 3:30 PM, Ivan Delamer wrote:
> There hasn't been a discussion about this yet. Feel free to propose one,
> or even better, a patch that implements it. I can review it and work it
> into the code if suitable.

Ivan,

Patches 7904 <https://savannah.nongnu.org/patch/index.php?7904> and 7905 
<https://savannah.nongnu.org/patch/index.php?7905> have been submitted. With 
these in place, a rudimentary ping6 to a link-local address works:

        > ping6 -c 4 fe80::ea06:88ff:fecc:a9f4
        PING fe80::ea06:88ff:fecc:a9f4 (FE80::EA06:88FF:FECC:A9F4): 56(104) 
bytes of data
        64 bytes from fe80::ea06:88ff:fecc:a9f4 (FE80::EA06:88FF:FECC:A9F4): 
icmp_seq=1 ttl=64 time=0.000 ms
        64 bytes from fe80::ea06:88ff:fecc:a9f4 (FE80::EA06:88FF:FECC:A9F4): 
icmp_seq=2 ttl=64 time=0.000 ms
        64 bytes from fe80::ea06:88ff:fecc:a9f4 (FE80::EA06:88FF:FECC:A9F4): 
icmp_seq=3 ttl=64 time=0.000 ms
        64 bytes from fe80::ea06:88ff:fecc:a9f4 (FE80::EA06:88FF:FECC:A9F4): 
icmp_seq=4 ttl=64 time=0.000 ms

        --- fe80::ea06:88ff:fecc:a9f4 ping statistics ---
        4 packets transmitted, 4 received, 0 duplicates, 0 errors 0% packet 
loss, time 6042ms
        round-trip min/avg/max = 0.000/0.000/0.000 ms

-Grant

> On Wed, December 19, 2012 10:21, Grant Erickson wrote:
>> I am implementing a basic ping6 test application for LwIP using a:
>> 
>>      socket = lwip_socket(AF_INET6, SOCK_RAW, IP6_NEXTH_ICMP6);
>> 
>> raw LWIP socket and it's mostly working, with checksum computation
>> excepted. Per RFC3542 <http://www.ietf.org/rfc/rfc3542.txt>, "3.1.
>> Checksums", outside of link-local addresses, for which a priori knowledge
>> is fairly straightforward, the source address for pseudo-header checksum
>> computation isn't easily derived from the application socket.
>> 
>> Have there been any strong opinions or directions toward supporting a raw
>> IPv6 checksum computation ala a socket option?