[PATCH 2.6.17] net/ipv6/udp.c: Enforce mandatory checksums as per RFC 2460

[gerrit@erg.abdn.ac.uk]

[UDPv6]: Enforce mandatory checksums as per RFC 2460

The current behaviour of computing outgoing checksums is not
compliant with RFC 2460, as per section 8.1:

 "Unlike IPv4, when UDP packets are originated by an IPv6 node,
  the UDP checksum is not optional.  That is, whenever
  originating a UDP packet, an IPv6 node must compute a UDP
  checksum over the packet and the pseudo-header, [...]"

This modification hence enforces to ignore sk_no_check on UDPv6.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
--

diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 8d3432a..5122c4d 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -567,11 +567,6 @@ static int udp_v6_push_pending_frames(st
        uh->len = htons(up->len);
        uh->check = 0;

-       if (sk->sk_no_check == UDP_CSUM_NOXMIT) {
-               skb->ip_summed = CHECKSUM_NONE;
-               goto send;
-       }
-
        if (skb_queue_len(&sk->sk_write_queue) == 1) {
                skb->csum = csum_partial((char *)uh,
                                sizeof(struct udphdr), skb->csum);