Merged in gvaladon/scapy-issues/Issue #5116 - IPv6 & UDP.chksum == 0 (pull request #112)

Issue #5116 fixed

Author: p-l-

scapy/layers/inet.py

@@ -517,6 +517,9 @@ def post_build(self, p, pay):
                 p = p[:6]+struct.pack("!H", ck)+p[8:]
             elif isinstance(self.underlayer, scapy.layers.inet6.IPv6) or isinstance(self.underlayer, scapy.layers.inet6._IPv6ExtHdr):
                 ck = scapy.layers.inet6.in6_chksum(socket.IPPROTO_UDP, self.underlayer, p)
+                # According to RFC2460 if the result checksum is 0, it should be set to 0xFFFF
+                if ck == 0:
+                    ck = 0xFFFF
                 p = p[:6]+struct.pack("!H", ck)+p[8:]
             else:
                 warning("No IP underlayer to compute checksum. Leaving null.")