如何用Wireshark lua编写的协议解析器，查看HTTP包的URI/URL的Query String里的参数

Wireshark解析HTTP GET方法不会解析URI里Query字符串里的参数（通常由GET方式提交form数据），本文介绍用lua编写一个简单的协议解析器，让这些参数解析出来，并显示在wireshark协议解析窗口里。

 

首先编写以下解析器lua脚本（用文本编辑器编辑即可），取文件名为my_http_querystring_decoder.lua：

-- Decode param=value from query string of http request uri (http.request.uri) -- Author: Huang Qiangxiong ([email protected]) -- change log: -- 2010-07-01 -- Just can play. ------------------------------------------------------------------------------------------------ do local querystring_decoder_proto = Proto("my_http_querystring_decoder", "Decoded HTTP URI Query String [HQX's plugins]") ---- url decode (from www.lua.org guide) function unescape (s) s = string.gsub(s, "+", " ") s = string.gsub(s, "%%(%x%x)", function (h) return string.char(tonumber(h, 16)) end) return s end ---- convert string to hex string function string2hex (s) local hex = ""; for i=1, #s, 1 do hex = hex .. string.format("%x", s:byte(i)) end return hex end local f_http_uri = Field.new("http.request.uri") ---- my dissector function querystring_decoder_proto.dissector(tvb, pinfo, tree) local http_uri = f_http_uri() -- ignore packages without "http.request.uri" if not http_uri then return end -- begin build my tree local content = http_uri.value local idx = content:find("?") if not idx then return end -- not include query string, so stop parsing local tab = ByteArray.new(string2hex(content)):tvb("Decoded HTTP URI Query String") local tab_range = tab() -- add proto item to tree local subtree = tree:add(querystring_decoder_proto, tab_range) -- add raw data to tree subtree:add(tab_range, "[HTTP Request URI] (" .. tab_range:len() .. " bytes)"):add(tab_range, content) -- add param value pair to tree local pairs_tree = subtree:add(tab_range, "[Decoded Query String]") local si = 1 local ei = idx local count = 0 while ei do si = ei + 1 ei = string.find(content, "&", si) local xlen = (ei and (ei - si)) or (content:len() - si + 1) if xlen > 0 then pairs_tree:add(tab(si-1, xlen), unescape(content:sub(si, si+xlen-1))) count = count + 1 end end pairs_tree:append_text(" (" .. count .. ")") end -- register this dissector register_postdissector(querystring_decoder_proto) end

 

然后修改wireshark安装目录下的init.lua文件：

（1）把disable_lua = true; do return end;这行注释掉：在前面加“--”

（2）然后在init.lua文件最后面加一句：dofile("my_http_querystring_decoder.lua")

OK大功告成，打开HTTP抓包，若其请求中URI带QueryString，则界面如下：

 

 可以看到，在协议解析树上新增了Decoded HTTP URI Query String ... 节点。看该节点下[HTTP Request URI]为原始HTTP Request URI，[Decoded Query String]下为解开后的一个个参数（经过url decode）。而且在wireshark的“Packet Bytes”窗口里新增了一个“Decoded HTTP URI Query String”的数据tab，专门显示HTTP URI内容，用于显示参数在URL里的原始形式。

 

 

另外，如果要解析HTTP Body部分的参数（用POST方法提交form数据），请参考《用Wireshark lua编写的协议解析器查看Content-Type为application/x-www-form-urlencoded的HTTP抓包》（http://blog.csdn.net/jasonhwang/archive/2010/04/25/5525700.aspx）。

 

注：wireshark版本为1.3.4

 

2015年更新：

-- Decode param=value from query string of http request uri (http.request.uri)
-- Author: Huang Qiangxiong ([email protected])
-- change log:
--      2010-07-01
--          Just can play.
------------------------------------------------------------------------------------------------
do
    local querystring_decoder_proto = Proto("my_http_querystring_decoder", "Decoded HTTP URI Query String [HQX's plugins]")

    ---- url decode (from www.lua.org guide)
    function unescape (s)
        s = string.gsub(s, "+", " ")
        s = string.gsub(s, "%%(%x%x)", function (h)
            return string.char(tonumber(h, 16))
        end)
        return s
    end
    
    ---- convert string to hex string
    function string2hex (s)
        local hex = "";
        for i=1, #s, 1 do
            hex = hex .. string.format("%x", s:byte(i))
        end
        return hex
    end
    
    local f_http_uri = Field.new("http.request.uri")

    ---- my dissector
    function querystring_decoder_proto.dissector(tvb, pinfo, tree)
        local http_uri = f_http_uri()
        -- ignore packages without "http.request.uri"
        if not http_uri then return end
        
        -- begin build my tree
        local content = http_uri.value
        local idx = content:find("?")
        if not idx then return end -- not include query string, so stop parsing
        
        local tab = ByteArray.new(string2hex(content)):tvb("Decoded HTTP URI Query String")
        local tab_range = tab()
        
        -- add proto item to tree
        local subtree = tree:add(querystring_decoder_proto, tab_range)
        
        -- add raw data to tree
        subtree:add(tab_range, "[HTTP Request URI] (" .. tab_range:len() .. " bytes)"):add(tab_range, content)

        -- add param value pair to tree
        local pairs_tree = subtree:add(tab_range, "[Decoded Query String]")
        local si = 1
        local ei = idx
        local count = 0
        while ei do
            si = ei + 1
            ei = string.find(content, "&", si)
            local xlen = (ei and (ei - si)) or (content:len() - si + 1)
            if xlen > 0 then
                --pairs_tree:add(tab(si-1, xlen), unescape(content:sub(si, si+xlen-1)))
                pairs_tree:add(tab(si-1, xlen), unescape(content:sub(si, si+xlen-1):gsub("=", " = ", 1)))
                count = count + 1
            end
        end
        pairs_tree:append_text(" (" .. count .. ")")
        
    end

    -- register this dissector
    register_postdissector(querystring_decoder_proto)
end