Added logic to compute ICRC for RoCEv2 over IPv6 (#4154)

* Added logic to compute ICRC for RoCEv2 over IPv6.

* Fixed RoCEv2 icrc computation.

---------

Co-authored-by: leonidokner <leonidokner@enfabrica.net>

Author: leonidokner-enf

scapy/contrib/roce.py

@@ -14,6 +14,7 @@
 from scapy.fields import ByteEnumField, ByteField, XByteField, \
     ShortField, XShortField, XLongField, BitField, XBitField, FCSField
 from scapy.layers.inet import IP, UDP
+from scapy.layers.inet6 import IPv6
 from scapy.layers.l2 import Ether
 from scapy.compat import raw
 from scapy.error import warning
@@ -179,8 +180,25 @@ def compute_icrc(self, p):
             pshdr[UDP].payload = Raw(bth + payload + icrc_placeholder)
             icrc = crc32(raw(pshdr)[:-4]) & 0xffffffff
             return self.pack_icrc(icrc)
+        elif isinstance(ip, IPv6):
+            # pseudo-LRH / IPv6 / UDP / BTH / payload
+            pshdr = Raw(b'\xff' * 8) / ip.copy()
+            pshdr.hlim = 0xff
+            pshdr.fl = 0xfffff
+            pshdr.tc = 0xff
+            pshdr[UDP].chksum = 0xffff
+            pshdr[BTH].fecn = 1
+            pshdr[BTH].becn = 1
+            pshdr[BTH].resv6 = 0xff
+            bth = pshdr[BTH].self_build()
+            payload = raw(pshdr[BTH].payload)
+            # add ICRC placeholder just to get the right IPv6.plen and
+            # UDP.length
+            icrc_placeholder = b'\xff\xff\xff\xff'
+            pshdr[UDP].payload = Raw(bth + payload + icrc_placeholder)
+            icrc = crc32(raw(pshdr)[:-4]) & 0xffffffff
+            return self.pack_icrc(icrc)
         else:
-            # TODO support IPv6
             warning("The underlayer protocol %s is not supported.",
                     ip and ip.name)
             return self.pack_icrc(0)

test/contrib/roce.uts

@@ -124,3 +124,24 @@ assert not pkt[BTH].ackreq
 assert pkt[AETH].syndrome == 0
 assert pkt[AETH].msn == 5
 assert pkt.icrc == 0x25f0c038
+
+= RoCE over IPv6
+
+# an example UC packet 
+pkt = Ether(dst='24:8a:07:a8:fa:22', src='24:8a:07:a8:fa:22')/ \
+      IPv6(nh=17,src='2022::1023', dst='2023::1024', \
+           version=6,hlim=255,plen=44,fl=0x1face,tc=226)/ \
+      UDP(sport=49152, dport=4791, len=44)/ \
+      BTH(opcode='UC_SEND_ONLY', migreq=1, padcount=2, pkey=0xffff, dqpn=211, psn=13571856)/ \
+      Raw(b'F0\x81\x8b\xe2\x895\xd9\x0e\x9a\x95PT\x01\xbe\x88^P\x00\x00')
+
+# include ICRC placeholder
+pkt = Ether(pkt.build() + b'\x00' * 4)
+
+assert IPv6 in pkt.layers()
+assert UDP in pkt.layers()
+print(hex(pkt[UDP].chksum))
+assert pkt[UDP].chksum == 0xe7c5
+assert BTH in pkt.layers()
+print(hex(pkt[BTH].icrc))
+assert pkt[BTH].icrc == 0x3e5b743b