anyproxy学习3-修改返回内容(beforeSendResponse)

前言

fiddler可以抓包打断点后，修改返回的内容，便于模拟各种返回结果。anyproxy也可以通过写rule模块规则，模拟返回状态码、头部、body

beforeSendResponse

beforeSendResponse(requestDetail, responseDetail)

• AnyProxy向客户端发送请求前，会调用beforeSendResponse，并带上参数requestDetail responseDetail
• requestDetail 同beforeSendRequest中的参数
• responseDetail
  
  response {object} 服务端的返回信息，包括statusCode header body三个字段
  
  _res {object} 原始的服务端返回对象

举例，请求 http://httpbin.org/get 时，responseDetail参数内容大致如下

{
  response: {
    statusCode: 200,
    header: {
      'Content-Type': 'image/gif',
      Connection: 'close',
      'Cache-Control': '...'
    },
    body: '...'
  },
  _res: { /* ... */ }
}

修改返回内容

以下几种返回都是合法的

不做任何处理，返回null

return null;

修改返回的状态码

var newResponse = Object.assign({}, responseDetail.response);
newResponse.statusCode = 404;
return {
  response: newResponse
};

修改返回的内容

var newResponse = Object.assign({}, responseDetail.response);
newResponse.body += '--from anyproxy--';
return {
  response: newResponse
};

rule案例

这里提供一些样例，来讲解规则模块的常见用法

你可以通过 anyproxy --rule http://....js 来加载模块并体验

用curl发请求测试的方法如下

• 直接请求服务器：curl http://httpbin.org/
• 通过代理服务器请求：curl http://httpbin.org/ --proxy http://127.0.0.1:8001

返回本地json格式body

使用本地数据，拦截发送到 http://httpbin.org 的请求，使用本地数据代替服务端返回，sample_use_local_response.js规则

/*
  sample:
    intercept all requests toward httpbin.org, use a local response
  test:
    curl http://httpbin.org/user-agent --proxy http://127.0.0.1:8001
*/
module.exports = {
  *beforeSendRequest(requestDetail) {
    const localResponse = {
      statusCode: 200,
      header: { 'Content-Type': 'application/json' },
      body: '{"hello": "this is local response"}'
    };
    if (requestDetail.url.indexOf('http://httpbin.org') === 0) {
      return {
        response: localResponse
      };
    }
  },
};

加载rule规则的js文件

anyproxy -i --rule sample_use_local_response.js

使用curl测试http://httpbin.org

C:\Users\dell>curl http://httpbin.org/user-agent --proxy http://127.0.0.1:8001

{"hello": "this is local response"}

模拟返回状态码

模拟返回404状态码,sample_modify_response_statuscode.js规则如下

/*
  sample:
    modify all status code of http://httpbin.org/ to 404
  test:
    curl -I 'http://httpbin.org/user-agent' --proxy http://127.0.0.1:8001
  expected response:
    HTTP/1.1 404 Not Found
*/
module.exports = {
  *beforeSendResponse(requestDetail, responseDetail) {
    if (requestDetail.url.indexOf('http://httpbin.org') === 0) {
      const newResponse = responseDetail.response;
      newResponse.statusCode = 404;
      return {
        response: newResponse
      };
    }
  }
};

模拟返回头部

修改返回的头部，sample_modify_response_header.js规则如下

/*
  sample:
    modify response header of http://httpbin.org/user-agent
  test:
    curl -I 'http://httpbin.org/user-agent' --proxy http://127.0.0.1:8001
  expected response:
    X-Proxy-By: AnyProxy
*/
module.exports = {
  *beforeSendResponse(requestDetail, responseDetail) {
    if (requestDetail.url.indexOf('http://httpbin.org/user-agent') === 0) {
      const newResponse = responseDetail.response;
      newResponse.header['X-Proxy-By'] = 'AnyProxy';
      return {
        response: newResponse
      };
    }
  }
};

修改返回body

修改返回的body里面部分内容，sample_modify_response_data.js规则如下

/*
  sample:
    modify response data of http://httpbin.org/user-agent
  test:
    curl 'http://httpbin.org/user-agent' --proxy http://127.0.0.1:8001
  expected response:
    { "user-agent": "curl/7.43.0" } -- AnyProxy Hacked! --
*/

module.exports = {
  *beforeSendResponse(requestDetail, responseDetail) {
    if (requestDetail.url === 'http://httpbin.org/user-agent') {
      const newResponse = responseDetail.response;
      newResponse.body += '-- AnyProxy Hacked! --';
      return new Promise((resolve, reject) => {
        setTimeout(() => { // delay the response for 5s
          resolve({ response: newResponse });
        }, 5000);
      });
    }
  },
};

更多学习资料参考https://github.com/alibaba/anyproxy/blob/master/docs/cn/src_doc.md