Init: hello + op

Initial Lua dissector. So far it can parse the hello handshake and the
store operation.

default.nix

@@ -0,0 +1,10 @@
+{ pkgs ? import <nixpkgs> {} }:
+
+pkgs.stdenv.mkDerivation {
+  pname = "nix-dissector";
+  version = "1.0";
+  nativeBuildInputs = [ pkgs.autoreconfHook pkgs.pkg-config ];
+  buildInputs = [ pkgs.wireshark.dev pkgs.glib ];
+  src = pkgs.lib.cleanSource ./.;
+
+}

flake.nix

@@ -0,0 +1,14 @@
+{
+  description = "Nix wireshark dissector";
+
+  inputs = {
+    nixpkgs.url = "github:Ninjatrappeur/nixpkgs/nin/wireshark-dev-fix";
+  };
+
+  outputs = { self, nixpkgs }: {
+
+    packages.x86_64-linux.nix-dissector = import ./default.nix { inherit (nixpkgs.legacyPackages.x86_64-linux) pkgs; };
+
+    devShells.x86_64-linux.default = self.packages.x86_64-linux.nix-dissector;
+  };
+}

nix-packet.lua

@@ -0,0 +1,122 @@
+local nix_proto = Proto("nix", "Nix Daemon Protocol")
+
+local dst_field = ProtoField.uint64("nix.dst", "Destination FD")
+local src_field = ProtoField.uint64("nix.src", "Source FD")
+
+local client_hello_field = ProtoField.bytes("nix.clienthello", "Client Hello")
+local client_hello_magic_field = ProtoField.uint64("nix.clienthello.magic", "Client magic number")
+local client_hello_version_field = ProtoField.uint64("nix.clienthello.version", "Client version")
+
+local daemon_hello_field = ProtoField.bytes("nix.daemonhello", "Daemon Hello")
+local daemon_hello_magic_field = ProtoField.uint64("nix.daemonhello.magic", "Daemon magic number")
+local daemon_hello_version_field = ProtoField.uint64("nix.daemonhello.protolversion", "Protocol Version")
+
+local op_name_field = ProtoField.string("nix.opname", "Operation Name")
+
+nix_proto.fields = {
+   dst_field,
+   src_field,
+   op_field,
+   first_byte_field,
+   client_hello_field,
+   client_hello_magic_field,
+   client_hello_version_field,
+   daemon_hello_field,
+   daemon_hello_magic_field,
+   daemon_hello_version_field,
+   op_name_field
+}
+
+local op_table = {
+   [1] = "IsValidPath",
+   [3] = "HasSubstitutes",
+   [4] = "QuaryPathHash",
+   [5] = "QueryReferences",
+   [6] = "QueryReferrers",
+   [7] = "AddToStore",
+   [8] = "AddTextToStore",
+   [9] = "BuildPaths",
+   [10] = "EnsurePath",
+   [11] = "AddTempRoot",
+   [12] = "AddIndirectRoot",
+   [13] = "SyncWithGC",
+   [14] = "FindRoots",
+   [16] = "ExportPath",
+   [18] = "QueryDeriver",
+   [19] = "SetOptions",
+   [20] = "CollectGarbage",
+   [21] = "QuerySubstitutablePathInfo",
+   [22] = "QueryDerivationOutputs",
+   [23] = "QueryAllValidPaths",
+   [24] = "QueryFailedPaths",
+   [25] = "ClearFailedPaths",
+   [26] = "QueryPathInfo",
+   [27] = "ImportPaths",
+   [28] = "QueryDerivationOutputNames",
+   [29] = "QueryPathFromHashPart",
+   [30] = "QuerySubstitutablePathInfos",
+   [31] = "QueryValidPaths",
+   [32] = "QuerySubstitutablePaths",
+   [33] = "QueryValidDerivers",
+   [34] = "OptimiseStore",
+   [35] = "VerifyStore",
+   [36] = "BuildDerivation",
+   [37] = "AddSignatures",
+   [38] = "NarFromPath",
+   [39] = "AddToStoreNar",
+   [40] = "QueryMissing",
+   [41] = "QueryDerivationOutputMap",
+   [42] = "RegisterDrvOutput",
+   [43] = "QueryRealisation",
+   [44] = "AddMultipleToStore",
+   [45] = "AddBuildLog",
+   [46] = "BuildPathsWithResults",
+}
+
+function parse_client_hello(tvb, pinfo, tree, offset)
+   local subtree = tree:add(client_hello_field, tvb:range(offset, 8))
+
+   subtree:add_le(client_hello_magic_field, tvb(offset,8))
+   return offset + 8
+end
+
+function parse_daemon_hello(tvb, pinfo, tree, offset)
+   local subtree = tree:add(daemon_hello_field, tvb:range(offset, 16))
+
+   subtree:add_le(daemon_hello_magic_field, tvb(offset,8))
+   offset = offset + 8
+
+   subtree:add_le(daemon_hello_version_field, tvb(offset,8))
+   return offset + 8
+end
+
+function parse_op(tvb, pinfo, tree, offset, op)
+   tree:add(op_name_field, tvb(offset, 8), op_table[op])
+end
+
+
+function nix_proto.dissector(tvb, pinfo, tree)
+   local offset = 0
+   local subtree = tree:add(nix_proto, tvb(), "Nix Daemon Protocol Data")
+   local dst = subtree:add(dst_field, tvb(offset, 8))
+   offset = offset + 8
+
+   local src = subtree:add(src_field, tvb(offset, 8))
+   offset = offset + 8
+
+   local first_word = tvb(offset, 4):le_uint()
+   if first_word == 0x6e697863 then
+      offset = parse_client_hello(tvb, pinfo, subtree, offset)
+   elseif first_word == 0x6478696f then
+      offset = parse_daemon_hello(tvb, pinfo, subtree, offset)
+   elseif op_table[first_word] ~= nil then
+      offset = parse_op(tvb, pinfo, subtree, offset, first_word)
+   end
+
+   pinfo.cols.protocol = "Nix Daemon"
+   pinfo.cols.dst = tostring(tvb(0, 8):uint64())
+   pinfo.cols.src = tostring(tvb(8, 8):uint64())
+end
+
+local wtap_encap_table = DissectorTable.get("wtap_encap")
+wtap_encap_table:add(wtap.USER0, nix_proto)