Add protocol header for ICMPv6 Packet-Too-Big type

src/lib/protocol/icmp/header.lua

@@ -16,7 +16,8 @@ local icmp = subClass(header)
 -- Class variables
 icmp._name = "icmp"
 icmp._ulp = {
-   class_map = { [135] = "lib.protocol.icmp.nd.ns",
+   class_map = { [2]   = "lib.protocol.icmp.ptb",
+                 [135] = "lib.protocol.icmp.nd.ns",
                  [136] = "lib.protocol.icmp.nd.na" },
    method    = "type" }
 icmp:init(

src/lib/protocol/icmp/ptb.lua

@@ -0,0 +1,37 @@
+-- Use of this source code is governed by the Apache 2.0 license; see COPYING.
+
+module(..., package.seeall)
+local ffi = require("ffi")
+local C = ffi.C
+local lib = require("core.lib")
+local proto_header = require("lib.protocol.header")
+
+local ptb = subClass(proto_header)
+
+-- Class variables
+ptb._name = "packet too big"
+ptb._ulp = { method = nil }
+proto_header.init(ptb,
+                  {
+                     -- The original packet follows the mtu. Because
+                     -- it is of variable size, it is considered as
+                     -- payload rather than part of the ICMP message
+                     -- so it can be retrieved with the datagram
+                     -- payload() method.
+                     [1] = ffi.typeof[[
+                           struct {
+                              uint32_t mtu;
+                           } __attribute__((packed))
+                     ]]
+                  })
+
+-- Instance methods
+
+function ptb:mtu (mtu)
+   if mtu ~= nil then
+      self:header().mtu = lib.htonl(mtu)
+   end
+   return lib.ntohl(self:header().mtu)
+end
+
+return ptb