Add handling ipv6 packets with No Next Header set but with meaningles…

…s payload

If the next header field is set to No Next Header (value 59) the ipv6 header
should not be followed by any header, not even a header of an upper layer
protocol. However there still can be data in the payload what can be deduced
from the payload length field. This data should be passed by routers.

src/pkt.erl

@@ -132,7 +132,10 @@ encapsulate([#arp{} = ARP | Packet], Binary) ->
 encapsulate([{unsupported, Unsupported} | Packet], Binary) ->
     encapsulate(unsupported, Packet, << Unsupported/binary, Binary/binary >>);
 encapsulate([{truncated, Truncated} | Packet], Binary) ->
-    encapsulate(truncated, Packet, << Truncated/binary, Binary/binary >>).
+    encapsulate(truncated, Packet, << Truncated/binary, Binary/binary >>);
+encapsulate([#ipv6{} | _] = Packet, Binary) ->
+    encapsulate(ipv6_hdr_no_next, Packet, Binary).
+
 
 -spec encapsulate(ether_type() | proto(), packet(), binary()) -> binary().
 encapsulate(_, [], Binary) ->

test/pkt_tests.erl

@@ -24,20 +24,20 @@ encapsulate_decapsulate_test_() ->
 
 encapsulate() ->
     [?assert(is_binary(pkt:encapsulate(generate_packet_model())))
-     || _ <- lists:seq(1, 10)].
+     || _ <- lists:seq(1, 100)].
 
 decapsulate() ->
     [begin
          BinaryPacket = pkt:encapsulate(generate_packet_model()),
          ?assert(is_list(pkt:decapsulate(BinaryPacket)))
-     end || _ <- lists:seq(1, 10)].
+     end || _ <- lists:seq(1, 100)].
 
 encapsulate_decapsulate() ->
     [begin
          PacketModel = generate_packet_model(),
          Decapsulated = pkt:decapsulate(pkt:encapsulate(PacketModel)),
          ?assertEqual(PacketModel, restore_computed_fields(Decapsulated))
-     end || _ <- lists:seq(1, 10)].
+     end || _ <- lists:seq(1, 100)].
 
 %% Fixtures -------------------------------------------------------------------
 
@@ -47,11 +47,11 @@ setup() ->
 %% Helper functions ------------------------------------------------------------
 
 generate_packet_model() ->
-    add_layer_header(transport, generate_binary(1400)).
+    add_layer_header(transport, generate_payload()).
 
 %% @private Add a TCP/IP model transport layer header to the payload.
 add_layer_header(transport, Payload) ->
-    Headers = [tcp, udp, none],
+    Headers = [tcp, udp, none, none],
     case lists:nth(random:uniform(length(Headers)), Headers) of
         tcp ->
             add_layer_header(internet, ?IPPROTO_TCP, [#tcp{} , Payload]);
@@ -63,9 +63,28 @@ add_layer_header(transport, Payload) ->
 
 %% @ private Add a header for the specified TCP/IP model layer.
 add_layer_header(internet, none, _Payload) ->
-    add_layer_header(link, ?ETH_P_IP, [#ipv4{p = ?IPPROTO_ICMP},
-                                       #icmp{},
-                                       generate_binary(1400)]);
+    Headers = [icmp, icmpv6, ipv6_no_next],
+    case lists:nth(random:uniform(length(Headers)), Headers) of
+        icmp ->
+            add_layer_header(link, ?ETH_P_IP, [#ipv4{p = ?IPPROTO_ICMP},
+                                               #icmp{},
+                                               generate_payload()]);
+        icmpv6 ->
+            add_layer_header(link, ?ETH_P_IPV6, [#ipv6{next = ?IPPROTO_ICMPV6,
+                                                       hop = 64,
+                                                       saddr = <<0:112, 1:16>>,
+                                                       daddr = <<0:112, 1:16>>},
+                                                 #icmpv6{},
+                                                 {unsupported,
+                                                  generate_payload()}]);
+        ipv6_no_next ->
+            add_layer_header(link, ?ETH_P_IPV6,
+                             [#ipv6{next = ?IPV6_HDR_NO_NEXT_HEADER,
+                                    hop = 64,
+                                    saddr = <<0:112, 1:16>>,
+                                    daddr = <<0:112, 1:16>>},
+                              generate_payload()])
+    end;
 add_layer_header(internet, Proto, Payload) ->
     Headers = [ipv4, ipv6],
     case lists:nth(random:uniform(length(Headers)), Headers) of
@@ -104,13 +123,22 @@ restore_computed_fields([#udp{} = UdpHeder | Rest], Packet) ->
     restore_computed_fields(Rest, [UdpHeder#udp{sum = 0, ulen = 8} | Packet]);
 restore_computed_fields([#icmp{} = IcmpHeader | Rest], Packet) ->
     restore_computed_fields(Rest, [IcmpHeader#icmp{checksum = 0} | Packet]);
+restore_computed_fields([#icmpv6{} = Icmpv6Header | Rest], Packet) ->
+    restore_computed_fields(Rest, [Icmpv6Header#icmpv6{checksum = 0} | Packet]);
 restore_computed_fields([#ipv4{} = IPv4Header | Rest], Packet) ->
     restore_computed_fields(Rest, [IPv4Header#ipv4{len = 20, sum = 0} | Packet]);
 restore_computed_fields([#ipv6{} = IPv6Header | Rest], Packet) ->
     restore_computed_fields(Rest, [IPv6Header#ipv6{len = 40} | Packet]);
 restore_computed_fields([Header | Rest], Packet) ->
     restore_computed_fields(Rest, [Header | Packet]).
 
-%% @private Generate random binary of given lenght in bytes.
-generate_binary(Length) ->
-    << <<(random:uniform(255))>> || _ <- lists:seq(1, Length) >>.
+%% @priavet Generate random binary payload.
+generate_payload() ->
+    generate_payload(random:uniform(1000) - 1).
+
+%% @private Generate random binary payload of the given max lenght in bytes.
+generate_payload(0) ->
+  <<>>;
+generate_payload(MexLength) ->
+    << <<(random:uniform(255))>>
+       || _ <- lists:seq(1, random:uniform(MexLength) div 8) >>.