flow: fix udp checksum

As per RFC 768, if the calculated UDP checksum is 0, it should be instead set as 0xFFFF in the frame. A value of 0 in the checksum field indicates to the receiver that no checksum was calculated and hence it should not verify the checksum. Signed-off-by: Li RongQing <[email protected]> Signed-off-by: Ben Pfaff <[email protected]>
yqnt418 · Jan 25, 2019 · 7a17a07 · 7a17a07
1 parent 2525148
commit 7a17a07
Showing 1 changed file with 3 additions and 0 deletions.
diff --git a/lib/flow.c b/lib/flow.c
@@ -3023,6 +3023,9 @@ flow_compose_l4_csum(struct dp_packet *p, const struct flow *flow,
             udp->udp_csum = 0;
             udp->udp_csum = csum_finish(csum_continue(pseudo_hdr_csum,
                                                       udp, l4_len));
+            if (!udp->udp_csum) {
+                udp->udp_csum = htons(0xffff);
+            }
         } else if (flow->nw_proto == IPPROTO_ICMP) {
             struct icmp_header *icmp = dp_packet_l4(p);