Added support for computing invariant CRC over IPv6

scapy/contrib/roce.py

@@ -9,7 +9,7 @@
 """
 RoCE: RDMA over Converged Ethernet
 """
-
+from scapy.layers.inet6 import IPv6
 from scapy.packet import Packet, bind_layers, Raw
 from scapy.fields import ByteEnumField, ByteField, XByteField, \
     ShortField, XShortField, XLongField, BitField, XBitField, FCSField
@@ -157,30 +157,38 @@ def compute_icrc(self, p):
             warning("Expecting UDP underlayer to compute checksum. Got %s.",
                     udp and udp.name)
             return self.pack_icrc(0)
+
         ip = udp.underlayer
-        if isinstance(ip, IP):
-            # pseudo-LRH / IP / UDP / BTH / payload
-            pshdr = Raw(b'\xff' * 8) / ip.copy()
+        # pseudo-LRH / IP / UDP / BTH / payload
+        pshdr = Raw(b'\xff' * 8) / ip.copy()
+        if isinstance(ip, IP):  # IPv4
             pshdr.chksum = 0xffff
             pshdr.ttl = 0xff
             pshdr.tos = 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 IP.totlen 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)
+
+        elif isinstance(ip, IPv6):  # IPv6
+            pshdr.fl = 0xfffff
+            pshdr.tc = 0xff
+            pshdr.hlim = 0xff
+
         else:
-            # TODO support IPv6
-            warning("The underlayer protocol %s is not supported.",
+            warning(f"The underlayer protocol %s is not supported.",
                     ip and ip.name)
-            return self.pack_icrc(0)
+            return struct.pack("!I", 0 & 0xffffffff)[::-1]
+
+        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 IP.totlen 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)
 
     # RoCE packets end with ICRC - a 32-bit CRC of the packet payload and
     # pseudo-header. Add the ICRC header if it is missing and calculate its

test/contrib/roce.uts

@@ -76,6 +76,7 @@ assert pkt.opcode == CNP_OPCODE
 del pkt.icrc
 pkt = Ether(pkt.build())
 assert pkt.icrc == 0x82fd002a
+assert int(pkt[BTH].compute_icrc(pkt).hex(), 16) == pkt.icrc
 
 = RoCE v1 RC RDMA WRITE ONLY
 
@@ -124,3 +125,29 @@ assert not pkt[BTH].ackreq
 assert pkt[AETH].syndrome == 0
 assert pkt[AETH].msn == 5
 assert pkt.icrc == 0x25f0c038
+
+= RoCE v2 RC ACKNOWLEDGE
+
+pkt = Ether(import_hexcap('''\
+0000   98 03 9b 99 51 3e 98 03 9b 99 51 42 81 00 60 00
+0010   86 dd 60 e0 00 00 00 1c 11 80 20 00 00 11 02 37
+0020   00 00 9a 03 9b ff fe 99 51 42 20 00 00 11 02 37
+0030   00 00 9a 03 9b ff fe 99 51 3e c1 a2 12 b7 00 1c
+0040   00 00 11 40 ff ff 00 00 0b af 00 08 0c 7b 00 00
+0050   00 01 84 06 28 9a
+'''))
+
+assert BTH in pkt.layers()
+assert AETH in pkt.layers()
+assert pkt[IPv6].version == 6
+assert pkt[IPv6].tc == 14
+assert pkt[IPv6].fl == 0
+assert pkt[IPv6].plen == 28
+assert pkt[BTH].opcode == 0x11
+assert pkt[BTH].padcount == 0
+assert pkt[BTH].dqpn == 0x000baf
+assert not pkt[BTH].ackreq
+assert pkt[AETH].syndrome == 0
+assert pkt[AETH].msn == 1
+assert pkt.icrc == 0x8406289a
+assert int(pkt[BTH].compute_icrc(pkt).hex(), 16) == pkt.icrc