Mysql-proxy中的lua指令碼編程(一)

標籤：

在為mysql-proxy編寫lua腳步的時候，需要知道一下幾個入口函數，通過這幾個入口函數我們可以控制mysql-proxy的一些行為。

• connect_server()          當Proxy 伺服器接受到用戶端串連請求時(tcp中的握手)會調用該函數
• read_handshake()        當mysql伺服器返回握手相應時會被調用
• read_auth()　　           當用戶端發送認證資訊(username,password,port,database)時會被調用
• read_auth_result(aut)  當mysql返回認證結果時會被調用
• read_query(packet)      當用戶端提交一個sql語句時會被調用
• read_query_result(inj)　當mysql返回查詢結果時會被調用

1.connect_server使用

function read_handshake( )    local con = proxy.connection    print("<-- let‘s send him some information about us")    print("    server-addr   : " .. con.server.dst.name)    print("    client-addr   : " .. con.client.src.name)

-- lets deny clients from !127.0.0.1
 　　if con.client.src.address ~= "127.0.0.1" then
  　　　　proxy.response.type = proxy.MYSQLD_PACKET_ERR
  　　　　proxy.response.errmsg = "only local connects are allowed"

　　　　　print("we don‘t like this client");

　　　　return proxy.PROXY_SEND_RESULT
 　　end

end

擷取代理的連結化物件，這個對象是全域的，可以在函數中直接拿來使用。從連線物件中我們可以拿到用戶端名稱和伺服器名稱，通過也能獲得用戶端的ip地址，上面的代碼就是禁止非本機ip登入mysql。

2、read_auth使用

讀取使用者的認證資訊包括使用者名稱、密碼、所要串連的資料庫。其中的proxy.MYSQLD_PACKET_ERR是mysql-proxy中內建的常量。

function read_auth( )    local con = proxy.connection    print("--> there, look, the client is responding to the server auth packet")    print("    username      : " .. con.client.username)    print("    password      : " .. string.format("%q", con.client.scrambled_password))    print("    default_db    : " .. con.client.default_db)    if con.client.username == "evil" then        proxy.response.type = proxy.MYSQLD_PACKET_ERR        proxy.response.errmsg = "evil logins are not allowed"                return proxy.PROXY_SEND_RESULT    endend

3.read_auth_result使用

通過該方法我們可以獲得mysql資料庫的認證結果，認證結果由auth對象持有，我們可以訪問其packet屬性(字串類型)，可以查看返回結果。字串的第一個字元是對結果的標識。

function read_auth_result( auth )    local state = auth.packet:byte()  //擷取第一個字元並將其轉為整型    if state == proxy.MYSQLD_PACKET_OK then        print("<-- auth ok");    elseif state == proxy.MYSQLD_PACKET_ERR then        print("<-- auth failed");    else        print("<-- auth ... don‘t know: " .. string.format("%q", auth.packet));    endend

4.read_query的使用

packet中就存放著客戶請求的SQL語句，類型為字串類型。起始第一個字元同上，為標識符。這裡判斷是不是一個查詢語句，是的話就從第二個字元開始輸出查詢語句。

function read_query( packet )     print("--> someone sent us a query")    if packet:byte() == proxy.COM_QUERY then        print("    query: " .. packet:sub(2))        if packet:sub(2) == "SELECT 1" then            proxy.queries:append(1, packet)        end    endend

5、read_query_result使用

其實我們該函數和read_query函數時是希望對SQL語句進行處理，但是由於時間有限，不能對mysql-proxy提供的sql處理繼續研究，這裡先就先貼出來。

function read_query_result( inj )     print("<-- ... ok, this only gets called when read_query() told us")    proxy.response = {        type = proxy.MYSQLD_PACKET_RAW,        packets = {             "\255" ..              "\255\004" .. -- errno              "#" ..              "12S23" ..              "raw, raw, raw"        }    }    return proxy.PROXY_SEND_RESULTend

--[[ $%BEGINLICENSE%$ Copyright (c) 2007, 2008, Oracle and/or its affiliates. All rights reserved. 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; version 2 of the License. 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 St, Fifth Floor, Boston, MA 02110-1301  USA $%ENDLICENSE%$ --]]local proto = require("mysql.proto")local prep_stmts = { }function read_query( packet )    local cmd_type = packet:byte()    if cmd_type == proxy.COM_STMT_PREPARE then        proxy.queries:append(1, packet, { resultset_is_needed = true } )        return proxy.PROXY_SEND_QUERY    elseif cmd_type == proxy.COM_STMT_EXECUTE then        proxy.queries:append(2, packet, { resultset_is_needed = true } )        return proxy.PROXY_SEND_QUERY    elseif cmd_type == proxy.COM_STMT_CLOSE then        proxy.queries:append(3, packet, { resultset_is_needed = true } )        return proxy.PROXY_SEND_QUERY    endendfunction read_query_result(inj)     if inj.id == 1 then        -- print the query we sent        local stmt_prepare = assert(proto.from_stmt_prepare_packet(inj.query))        print(("> PREPARE: %s"):format(stmt_prepare.stmt_text))        -- and the stmt-id we got for it        if inj.resultset.raw:byte() == 0 then            local stmt_prepare_ok = assert(proto.from_stmt_prepare_ok_packet(inj.resultset.raw))            print(("< PREPARE: stmt-id = %d (resultset-cols = %d, params = %d)"):format(                stmt_prepare_ok.stmt_id,                stmt_prepare_ok.num_columns,                stmt_prepare_ok.num_params))            prep_stmts[stmt_prepare_ok.stmt_id] = {                num_columns = stmt_prepare_ok.num_columns,                num_params = stmt_prepare_ok.num_params,            }        end    elseif inj.id == 2 then        local stmt_id = assert(proto.stmt_id_from_stmt_execute_packet(inj.query))        local stmt_execute = assert(proto.from_stmt_execute_packet(inj.query, prep_stmts[stmt_id].num_params))        print(("> EXECUTE: stmt-id = %d"):format(stmt_execute.stmt_id))        if stmt_execute.new_params_bound then            for ndx, v in ipairs(stmt_execute.params) do                print((" [%d] %s (type = %d)"):format(ndx, tostring(v.value), v.type))            end        end    elseif inj.id == 3 then        local stmt_close = assert(proto.from_stmt_close_packet(inj.query))        print(("> CLOSE: stmt-id = %d"):format(stmt_close.stmt_id))        prep_stmts[stmt_close.stmt_id] = nil -- cleanup    endend

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這裡使用了MySQL新的介面stmt,對其不瞭解可以查看下面的串連。

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Mysql-proxy中的lua指令碼編程(一)