Splitting FieldExtractor into Field and FieldInfo to more closely res…

…emble the wireshark API.

wirebaitlib/dissector/DissectorRunner.lua

@@ -108,7 +108,7 @@ function DissectorRunnerClass.new(options_table) --[[options_table uses named ar
     newgt.Int64            = require("wirebaitlib.primitives.Int64");
     newgt.ProtoField       = require("wirebaitlib.dissector.ProtoField");
     newgt.Proto            = require("wirebaitlib.dissector.Proto").new;
-    newgt.Field            = require("wirebaitlib.dissector.FieldExtractor").Field;
+    newgt.Field            = require("wirebaitlib.dissector.Field");
     newgt.ftypes           = newgt.ProtoField.ftypes;
     newgt.base             = newgt.ProtoField.base;
     newgt.__wirebait_state = createRunnerState(); --TODO: this is not used

wirebaitlib/dissector/Field.lua

@@ -0,0 +1,76 @@
+--[[
+    WireBait for wirebait is a lua package to help write Wireshark
+    Dissectors in lua
+    [Wirebait on Github](https://github.com/MarkoPaul0/WireBait)
+    Copyright (C) 2015-2017 Markus Leballeux
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License along
+    with this program; if not, write to the Free Software Foundation, Inc.,
+    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+]]
+
+local FieldInfoClass = require("wirebaitlib.dissector.FieldInfo");
+
+local FieldClass = {};
+
+--TODO: enforce the fact that a field must be defined before Taps or Dissectors get called
+--[[
+    //Constructor
+    <Field> FieldClass.new(<string> fieldname)
+
+    example of fieldname = "ip.src"
+]]
+function FieldClass.new(fieldname)
+    local field = {
+        m_field_info  = nil;
+        name          = fieldname;
+        display       = nil;
+        type          = nil;
+    };
+
+    ---------------------------------------------- initialization ------------------------------------------------------
+
+    for _, v in pairs(__wirebait_state.proto.fields) do
+        if v.m_abbr == fieldname then
+            field.m_field_info = FieldInfoClass.new(v);
+            field.name         = v.m_abbr;
+            field.display      = v.m_name;
+            field.type         = v.m_type;
+        end
+    end
+    if not field.m_field_info then
+        error("The dissector has no defined field '" .. field_path .. "' the field extractor could find!");
+    end
+
+    ------------------------------------------------ metamethods -------------------------------------------------------
+
+    function field:__tostring()
+        return self.name;
+    end
+
+    --TODO: enfore the fact that fields cannot be used outside of dissector or tap
+    function field:__call()
+        return self.m_field_info;
+    end
+
+    setmetatable(field, field)
+
+    return field;
+end
+
+--[[TODO: we need a Field.List() (which might not be defined in this library) as described here:fieldname
+--https://www.wireshark.org/docs/wsdg_html_chunked/lua_module_Field.html#lua_class_Field
+--c.f. item  11.2.1.2. Field.list()
+]]
+
+return FieldClass;

wirebaitlib/dissector/FieldExtractor.lua → wirebaitlib/dissector/FieldInfo.lua

@@ -21,62 +21,49 @@
 
 --TODO: this class is a work in progress
 
-local FieldExtractor = { FieldInfo = {}, Field = {} };
+local FieldInfoClass = {};
 
-function FieldExtractor.FieldInfo.new(protofield)
+function FieldInfoClass.new(protofield)
     assert(protofield);
     local field_info = {
         m_protofield = protofield;
     }
 
+    ------------------------------------------------ metamethods -------------------------------------------------------
+
     function field_info:__len()
-        --print("[WARNING] FieldInfo:__len() is not supported yet! Contact MarkoPaul0, the Wirebait developer.");
-        return 0;
+        error("FieldInfo:__len() is not supported yet!");
     end
 
     function field_info:__unm()
-        error("FieldInfo:__unm() is not supported yet! Contact MarkoPaul0, the Wirebait developer.");
+        error("FieldInfo:__unm() is not supported yet!");
     end
 
     function field_info:__call()
         return self.m_protofield:getValueFromBuffer(self.m_protofield.m_last_buffer);
-        --error("TODO: FieldInfo:__call()");
     end
 
-    setmetatable(field_info, field_info)
-    return field_info;
-end
-
-function FieldExtractor.Field.new(field_path) --Field Extractors
-    local field = {
-        m_info = nil;
-        name = nil;
-        display = nil;
-    };
-
-    for k, v in pairs(__wirebait_state.proto.fields) do
-        if v.m_abbr == field_path then
-            field.m_info = FieldExtractor.FieldInfo.new(v);
-            field.name = v.m_abbr;
-            field.display = v.m_name;
-            field['type'] = v.m_type;
-        end
+    function field_info:__tostring()
+        return self.m_protofield:getDisplayValueFromBuffer(self.m_protofield.m_last_buffer);
     end
-    if not field.m_info then
-        error("The dissector has no defined field '" .. field_path .. "' the field extractor could find!");
+
+    function field_info.__le()
+        error("FieldInfo.__le() is not supported yet");
     end
 
-    function field:__tostring()
-        return self.name;
+    function field_info.__lt()
+        error("FieldInfo.__lt() is not supported yet");
     end
 
-    function field:__call()
-        return self.m_info;
+    function field_info.__eq()
+        error("FieldInfo.__eq() is not supported yet");
     end
 
-    setmetatable(field, field)
-    --table.insert(state.field_extractors, field);
-    return field;
+    setmetatable(field_info, field_info)
+
+    return field_info;
 end
 
-return FieldExtractor;
+
+
+return FieldInfoClass;