在为mysql-proxy编写lua脚步的时候，需要知道一下几个入口函数，通过这几个入口函数我们可以控制mysql-proxy的一些行为。
- connect_server() 当代理服务器接受到客户端连接请求时(tcp中的握手)会调用该函数
- read_handshake() 当mysql服务器返回握手相应时会被调用
- read_auth() 当客户端发送认证信息(username,password,port,database)时会被调用
- read_auth_result(aut) 当mysql返回认证结果时会被调用
- read_query(packet) 当客户端提交一个sql语句时会被调用
- read_query_result(inj) 当mysql返回查询结果时会被调用
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
获取代理的链接对象，这个对象是全局的，可以在函数中直接拿来使用。从连接对象中我们可以拿到客户端名称和服务器名称，通过也能获得客户端的ip地址，上面的代码就是禁止非本机ip登录mysql。
2、read_auth使用
读取用户的认证信息包括用户名、密码、所要连接的数据库。其中的proxy.MYSQLD_PACKET_ERR是mysql-proxy中自带的常量。
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
通过该方法我们可以获得mysql数据库的认证结果，认证结果由auth对象持有，我们可以访问其packet属性(字符串类型)，可以查看返回结果。字符串的第一个字符是对结果的标识。
function read_auth_result( auth ) local state = auth.packet:byte() //获取第一个字符并将其转为整型 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中就存放着客户请求的SQL语句，类型为字符串类型。起始第一个字符同上，为标识符。这里判断是不是一个查询语句，是的话就从第二个字符开始输出查询语句。
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
其实我们该函数和read_query函数时是希望对SQL语句进行处理，但是由于时间有限，不能对mysql-proxy提供的sql处理继续研究，这里先就先贴出来。
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 这里使用了MySQL新的接口stmt,对其不了解可以查看下面的连接。