支持_ip_参数，重写请求

index.js

 'use strict'
 const request = require('request')
 const debug = require('debug')('request-proxy')
+const qs = require('querystring')
 
 const Agent = require('agentkeepalive');
 const HttpsAgent = require('agentkeepalive').HttpsAgent;
@@ -48,6 +49,11 @@ module.exports = function (options) {
     timeout: options.timeout
   }
 
+  const isProduction = process.env.NODE_ENV === 'production'
+  const rewriteUrl = function (source, to) {
+    return source.replace(/\/\/([^\/]+)\//, `//${to}/`).replace(/_ip_=[\w\.:%]+&?/, '')
+  }
+
   const httpAgent = new Agent(options.agent);
   const httpsAgent = new HttpsAgent();
 
@@ -67,6 +73,10 @@ module.exports = function (options) {
       option = Object.assign({}, curlDefault, option)
       extra = Object.assign({}, extraDefault, extra)
 
+      if (!isProduction && ctx.request.query['_ip_']) {
+        option.url = rewriteUrl(option.url, ctx.request.query['_ip_'])
+      }
+
       debug(option)
 
       if (!option.agent && !/^https/.test(option.url)) {
@@ -100,6 +110,10 @@ module.exports = function (options) {
       }
       option = Object.assign({}, pipeDefault, option)
 
+      if (!isProduction && ctx.request.query['_ip_']) {
+        option.url = rewriteUrl(option.url, ctx.request.query['_ip_'])
+      }
+
       if (!option.method) {
         option.method = ctx.method
       }

package.json

 {
   "name": "request-proxy",
-  "version": "1.0.4",
+  "version": "1.0.5",
   "description": "",
   "main": "index.js",
   "scripts": {