node-http-proxy.js

/*
  node-http-proxy.js: http proxy for node.js

  Copyright (c) 2010 Charlie Robbins, Mikeal Rogers, Marak Squires, Fedor Indutny 

  Permission is hereby granted, free of charge, to any person obtaining
  a copy of this software and associated documentation files (the
  "Software"), to deal in the Software without restriction, including
  without limitation the rights to use, copy, modify, merge, publish,
  distribute, sublicense, and/or sell copies of the Software, and to
  permit persons to whom the Software is furnished to do so, subject to
  the following conditions:

  The above copyright notice and this permission notice shall be
  included in all copies or substantial portions of the Software.

  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

*/

var util = require('util'),
    http = require('http'),
    events = require('events'),
    winston = require('winston'),
    ProxyTable = require('./proxy-table').ProxyTable,
    maxSockets = 100;

exports.version = [0, 4, 2];

function _getAgent (host, port) {

  var agent = http.getAgent(host, port);
  agent.maxSockets = maxSockets;
  return agent;
}

exports.getMaxSockets = function () {
  return maxSockets;
};

exports.setMaxSockets = function (value) {
  maxSockets = value;
};

exports.createServer = function () {
  var args, callback, port, host, forward, 
      silent, options, proxy, server;
  
  args = Array.prototype.slice.call(arguments);
  callback = typeof args[args.length - 1] === 'function' && args.pop();
  
  if (args.length >= 2) {
    port = args[0];
    host = args[1];
    options = args[2] || {};
  } 
  else if (args.length === 1) {
    options = args[0] || {};
    if (!options.router && !callback) {
      throw new Error('Cannot create server with no router and no callback');
    }
  }

  proxy = new HttpProxy(options);
  server = http.createServer(function (req, res) {
    winston.verbose('Incoming HTTP request to: ' + req.headers.host + req.url);

    if (callback) {
      callback(req, res, proxy);
    } 
    else if (port && host) {
      winston.verbose('Proxying HTTP request to: ' + host + ':' + port);
      proxy.proxyRequest(req, res, port, host);
    }
    else if (proxy.proxyTable) {
      winston.verbose('Proxying request using proxy table');
      proxy.proxyRequest(req, res);
    }
    else {
      throw new Error('Cannot proxy without port, host, or router.')
    }
  });
  
  server.on('close', function () {
    proxy.close();
  });
  
  proxy.on('routes', function (routes) {
    server.emit('routes', routes);
  });

  if (!callback) {

    server.on('upgrade', function(req, socket, head) {

      
      proxy.proxyWebSocketRequest(port, host);
    });
  }

  return server;
};

var HttpProxy = exports.HttpProxy = function (options) {
  events.EventEmitter.call(this);
  
  options = options || {};
  this.options = options;
  
  if (options.router) {
    var self = this;
    this.proxyTable = new ProxyTable(options.router, options.silent, options.hostnameOnly);
    this.proxyTable.on('routes', function (routes) {
      self.emit('routes', routes);
    });
  }
};

util.inherits(HttpProxy, events.EventEmitter);

HttpProxy.prototype.buffer = function (obj) {
  var onData, onEnd, events = [];

  obj.on('data', onData = function (data, encoding) {
    events.push(['data', data, encoding]);
  });

  obj.on('end', onEnd = function (data, encoding) {
    events.push(['end', data, encoding]);
  });

  return {
    end: function () {
      obj.removeListener('data', onData);
      obj.removeListener('end', onEnd);
    },
    resume: function () {
      this.end();
      for (var i = 0, len = events.length; i < len; ++i) {
        obj.emit.apply(obj, events[i]);
      }
    }
  };
};

HttpProxy.prototype.close = function () {
  if (this.proxyTable) this.proxyTable.close();
};

HttpProxy.prototype.proxyRequest = function (req, res, port, host, buffer) {
  var self = this, reverseProxy, location, errState = false, opts;
  

  if (this.proxyTable && !host) {
    location = this.proxyTable.getProxyLocation(req);
    

    if (!location) {
      res.writeHead(404);
      return res.end();
    }
    

    buffer = port;
    port = location.port;
    host = location.host;
  }
  

  if (this.options.forward) {
    winston.verbose('Forwarding HTTP request to: ' + this.options.forward.host + ':' + this.options.forward.port);
    this._forwardRequest(req);
  }
  

  function proxyError(err) {
    errState = true;
    res.writeHead(500, { 'Content-Type': 'text/plain' });

    if (req.method !== 'HEAD') {
      res.write('An error has occurred: ' + JSON.stringify(err));
    }
  
    res.end();
  }
  
  var opts = {
    host: host,
    port: port,
    agent: _getAgent(host, port),
    method: req.method,
    path: req.url,
    headers: req.headers
  };
  

  opts.headers['connection'] = 'close';
  

  reverseProxy = http.request(opts, function (response) {
    

    if (response.headers.connection) {
      if (req.headers.connection) response.headers.connection = req.headers.connection;
      else response.headers.connection = 'close';
    }

    res.writeHead(response.statusCode, response.headers);

    if (response.statusCode === 304) {
      return res.end();
    }

    response.on('data', function (chunk) {
      if (req.method !== 'HEAD') {
        res.write(chunk);
      }
    });

    response.on('end', function () {
      if (!errState) {
        reverseProxy.removeListener('error', proxyError);
        res.end();
      }
    });
  });
  

  reverseProxy.once('error', proxyError);
  

  req.on('data', function (chunk) {
    if (!errState) {
      reverseProxy.write(chunk);
    }
  });

  req.on('end', function () {
    if (!errState) {
      reverseProxy.end();
    }
  });

  if (buffer && !errState) {
    buffer.resume();
  }
};
  

HttpProxy.prototype._forwardRequest = function (req) {
  var self = this, port, host, forwardProxy, opts;

  port = this.options.forward.port;
  host = this.options.forward.host;
  
  opts = {
    host: host,
    port: port,
    agent: _getAgent(host, port),
    method: req.method,
    path: req.url,
    headers: req.headers
  };
  

  opts.headers['connection'] = 'close';
  

  forwardProxy = http.request(opts, function (response) {

  });
  

  forwardProxy.once('error', function (err) { });

  req.on('data', function (chunk) {
    forwardProxy.write(chunk);
  })

  req.on('end', function () {
    forwardProxy.end();
  });
};

HttpProxy.prototype.proxyWebSocketRequest = function (port, server, host, data) {
  var self = this, req = self.req, socket = self.sock, head = self.head, 
      headers = new _headers(req.headers), CRLF = '\r\n';

  function _headers(headers) {
    var h = {};
    for (var i in headers) {
      h[i] = headers[i];
    }
    return h;
  }

  if (req.method !== 'GET' || headers.upgrade.toLowerCase() !== 'websocket') {

    return;
  }

  function _socket(socket, server) {
    socket.setTimeout(0);
    socket.setNoDelay(true);
    if (server) {
      socket.setKeepAlive(true, 0);
    } 
    else {
      socket.setEncoding('utf8');
    }
  }

  _socket(socket);

  if (!host) {
    host = headers.Host;
  }
  

  var remote_host = server + (port - 80 === 0 ? '' : ':' + port);

  headers.Host = remote_host;
  headers.Origin = 'http://' + remote_host;

  var p = manager.getPool(port, server);

  p.getClient(function(client) {

    var request = client.request('GET', req.url, headers);

    var errorListener = function (error) {
      client.removeListener('error', errorListener);
      

      p.clients.splice(p.clients.indexOf(client), 1);
      socket.end();
    }

    client.on('upgrade', function(request, remote_socket, head) {

      _socket(remote_socket, true);

      onUpgrade(remote_socket);
    });

    client.on('error', errorListener);
    request.on('response', function (response) {
      response.on('end', function () {
        client.removeListener('error', errorListener);
        client.busy = false;
        p.onFree(client);
      })
    })
    client.busy = true;

    var handshake;
    request.socket.on('data', handshake = function(data) {

      var sdata = data.toString();

      sdata = sdata.substr(0, sdata.search(CRLF + CRLF));

      data = data.slice(Buffer.byteLength(sdata), data.length);

      sdata = sdata.replace(remote_host, host)
                   .replace(remote_host, host);

      try {

        socket.write(sdata);

        socket.write(data);
      } 
      catch (e) {
        request.end();
        socket.end();
      }

      socket.on('error', function() {
        request.end();
      });

      request.socket.removeListener('data', handshake);
    });

    try {
      request.write(head);
    } 
    catch(e) {
      request.end();
      socket.end();
    }
    self.unwatch(socket);
  });

  function onUpgrade(reverse_proxy) {
    var listeners = {};
    

    reverse_proxy.on('data', listeners._r_data = function(data) {

      if (socket.writable) {
        try {
          socket.write(data);
        } 
        catch (e) {
          socket.end();
          reverse_proxy.end();
        }
      }
    });

    socket.on('data', listeners._data = function(data) {

      try {
        reverse_proxy.write(data);
      } 
      catch (e) {
        reverse_proxy.end();
        socket.end();
      }
    });

    function detach() {
      reverse_proxy.removeListener('close', listeners._r_close);
      reverse_proxy.removeListener('data', listeners._r_data);
      socket.removeListener('data', listeners._data);
      socket.removeListener('close', listeners._close);
    }

    reverse_proxy.on('end', listeners._r_close = function() {
      socket.end();
      detach();
    });

    socket.on('end', listeners._close = function() {
      reverse_proxy.end();
      detach();
    });
  };
};