如何使用 Node.js 创建一个 API 代理？

Question

由于 GFW 屏蔽了包括 flickr 在内的一些 IP，我想用 Node.js 创建一个 API 代理，但是我在 http 服务器中打开 GET 请求时遇到了问题。这是我的代码：

var http = require('http');
var qs = require('querystring');
var curl = require('request');
var serverPort = 3000;
http.createServer(function (request, response) {
  if(request.method === "GET") {
    response.writeHead(401, {'Content-Type': 'text/html'});
    response.write('<!doctype html><html><head><title>401</title></head><body>401: Unauthorized</body></html>');
    response.end();
  } else if(request.method === "POST") {
    if (request.url === "/") {
      var requestBody = '';
      request.on('data', function(data) {
        requestBody += data;
        if(requestBody.length > 1e7) {
          response.writeHead(413, 'Request Entity Too Large', {'Content-Type': 'text/html'});
          response.end('413: Request Entity Too Large');
        }
      });
      request.on('end', function() {
        var body = getrequest();
        if (body === false) {
          response.writeHead(502, 'Bad Gateway', {'Content-Type': 'text/html'});
          response.end('502: Bad Gateway');
        } else {
          response.writeHead(200, {'Content-Type': 'text/html'});
          response.write(body);
          response.end();
        }
      });
    } else {
      response.writeHead(404, 'Resource Not Found', {'Content-Type': 'text/html'});
      response.end('<!doctype html><html><head><title>404</title></head><body>404: Resource Not Found</body></html>');
    }
  } else {
    response.writeHead(405, 'Method Not Supported', {'Content-Type': 'text/html'});
    return response.end('<!doctype html><html><head><title>405</title></head><body>405: Method Not Supported</body></html>');
  }
}).listen(serverPort);
function getrequest(){
  return curl('https://api.flickr.com/services/rest/?method=flickr.photosets.getList&api_key={{insert_ur_api_key}}&user_id={{insert_ur_user_id}}&format=json', function (error, response, body) {
    if (error) {
      return false;
    } else {
      return body;
    }
  });
}
console.log('Server running at localhost:'+serverPort);

在此示例中，我使用了 request 包（使用 npm install request 进行安装）。

错误信息如下：

_http_outgoing.js:655
    throw new TypeError('First argument must be a string or Buffer');
    ^

TypeError: First argument must be a string or Buffer
    at write_ (_http_outgoing.js:655:11)
    at ServerResponse.write (_http_outgoing.js:630:10)
    at IncomingMessage.<anonymous> (/Users/aero/Documents/Design/0522-aerofotea api/www/index.js:28:20)
    at emitNone (events.js:105:13)
    at IncomingMessage.emit (events.js:207:7)
    at endReadableNT (_stream_readable.js:1045:12)
    at _combinedTickCallback (internal/process/next_tick.js:102:11)
    at process._tickCallback (internal/process/next_tick.js:161:9)

Answer 1

我觉得问题是response.write(getrequest());

getrequest是一个async action，你应该使用callback或者promisify。如果使用回调，getrequest函数应该是这样的：

function getrequest(callback){
    curl('https://api.flickr.com/services/rest/?method=flickr.photosets.getList&api_key={{insert_ur_api_key}}&user_id={{insert_ur_user_id}}&format=json', (error, response, body)=> {
      if (error) {
          callback(error);
          return;
      } 
      callback(null, body);
    });
}

然后像这样使用它：

request.on('end', function() {
    getrequest((err, body)=>{
       if (err) {
           response.writeHead(502, 'Bad Gateway', {'Content-Type': 'text/html'});
           response.end('502: Bad Gateway');
       } else {
           response.writeHead(200, {'Content-Type': 'text/html'});
           response.write(body);
           response.end();
       }
    })
})

如何使用 Node.js 创建一个 API 代理？

How to make an API proxy with Node.js?

api

proxy

node.js

get-request