nodejs/lib/http.js

// Copyright Joyent, Inc. and other Node contributors.
//
// 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');
var net = require('net');
var url = require('url');
var EventEmitter = require('events').EventEmitter;
var HTTPParser = process.binding('http_parser').HTTPParser;
var assert = require('assert').ok;


var incoming = require('_http_incoming');
var IncomingMessage = exports.IncomingMessage = incoming.IncomingMessage;


var common = require('_http_common');
var parsers = exports.parsers = common.parsers;
var freeParser = common.freeParser;
var debug = common.debug;
var CRLF = common.CRLF;
var continueExpression = common.continueExpression;
var chunkExpression = common.chunkExpression;


var STATUS_CODES = exports.STATUS_CODES = {
  100 : 'Continue',
  101 : 'Switching Protocols',
  102 : 'Processing',                 // RFC 2518, obsoleted by RFC 4918
  200 : 'OK',
  201 : 'Created',
  202 : 'Accepted',
  203 : 'Non-Authoritative Information',
  204 : 'No Content',
  205 : 'Reset Content',
  206 : 'Partial Content',
  207 : 'Multi-Status',               // RFC 4918
  300 : 'Multiple Choices',
  301 : 'Moved Permanently',
  302 : 'Moved Temporarily',
  303 : 'See Other',
  304 : 'Not Modified',
  305 : 'Use Proxy',
  307 : 'Temporary Redirect',
  400 : 'Bad Request',
  401 : 'Unauthorized',
  402 : 'Payment Required',
  403 : 'Forbidden',
  404 : 'Not Found',
  405 : 'Method Not Allowed',
  406 : 'Not Acceptable',
  407 : 'Proxy Authentication Required',
  408 : 'Request Time-out',
  409 : 'Conflict',
  410 : 'Gone',
  411 : 'Length Required',
  412 : 'Precondition Failed',
  413 : 'Request Entity Too Large',
  414 : 'Request-URI Too Large',
  415 : 'Unsupported Media Type',
  416 : 'Requested Range Not Satisfiable',
  417 : 'Expectation Failed',
  418 : 'I\'m a teapot',              // RFC 2324
  422 : 'Unprocessable Entity',       // RFC 4918
  423 : 'Locked',                     // RFC 4918
  424 : 'Failed Dependency',          // RFC 4918
  425 : 'Unordered Collection',       // RFC 4918
  426 : 'Upgrade Required',           // RFC 2817
  428 : 'Precondition Required',      // RFC 6585
  429 : 'Too Many Requests',          // RFC 6585
  431 : 'Request Header Fields Too Large',// RFC 6585
  500 : 'Internal Server Error',
  501 : 'Not Implemented',
  502 : 'Bad Gateway',
  503 : 'Service Unavailable',
  504 : 'Gateway Time-out',
  505 : 'HTTP Version Not Supported',
  506 : 'Variant Also Negotiates',    // RFC 2295
  507 : 'Insufficient Storage',       // RFC 4918
  509 : 'Bandwidth Limit Exceeded',
  510 : 'Not Extended',               // RFC 2774
  511 : 'Network Authentication Required' // RFC 6585
};


var outgoing = require('_http_outgoing');
var OutgoingMessage = exports.OutgoingMessage = outgoing.OutgoingMessage;



function ServerResponse(req) {
  OutgoingMessage.call(this);

  if (req.method === 'HEAD') this._hasBody = false;

  this.sendDate = true;

  if (req.httpVersionMajor < 1 || req.httpVersionMinor < 1) {
    this.useChunkedEncodingByDefault = chunkExpression.test(req.headers.te);
    this.shouldKeepAlive = false;
  }
}
util.inherits(ServerResponse, OutgoingMessage);


exports.ServerResponse = ServerResponse;

ServerResponse.prototype.statusCode = 200;

function onServerResponseClose() {
  // EventEmitter.emit makes a copy of the 'close' listeners array before
  // calling the listeners. detachSocket() unregisters onServerResponseClose
  // but if detachSocket() is called, directly or indirectly, by a 'close'
  // listener, onServerResponseClose is still in that copy of the listeners
  // array. That is, in the example below, b still gets called even though
  // it's been removed by a:
  //
  //   var obj = new events.EventEmitter;
  //   obj.on('event', a);
  //   obj.on('event', b);
  //   function a() { obj.removeListener('event', b) }
  //   function b() { throw "BAM!" }
  //   obj.emit('event');  // throws
  //
  // Ergo, we need to deal with stale 'close' events and handle the case
  // where the ServerResponse object has already been deconstructed.
  // Fortunately, that requires only a single if check. :-)
  if (this._httpMessage) this._httpMessage.emit('close');
}

ServerResponse.prototype.assignSocket = function(socket) {
  assert(!socket._httpMessage);
  socket._httpMessage = this;
  socket.on('close', onServerResponseClose);
  this.socket = socket;
  this.connection = socket;
  this.emit('socket', socket);
  this._flush();
};

ServerResponse.prototype.detachSocket = function(socket) {
  assert(socket._httpMessage == this);
  socket.removeListener('close', onServerResponseClose);
  socket._httpMessage = null;
  this.socket = this.connection = null;
};

ServerResponse.prototype.writeContinue = function() {
  this._writeRaw('HTTP/1.1 100 Continue' + CRLF + CRLF, 'ascii');
  this._sent100 = true;
};

ServerResponse.prototype._implicitHeader = function() {
  this.writeHead(this.statusCode);
};

ServerResponse.prototype.writeHead = function(statusCode) {
  var reasonPhrase, headers, headerIndex;

  if (typeof arguments[1] == 'string') {
    reasonPhrase = arguments[1];
    headerIndex = 2;
  } else {
    reasonPhrase = STATUS_CODES[statusCode] || 'unknown';
    headerIndex = 1;
  }
  this.statusCode = statusCode;

  var obj = arguments[headerIndex];

  if (obj && this._headers) {
    // Slow-case: when progressive API and header fields are passed.
    headers = this._renderHeaders();

    if (Array.isArray(obj)) {
      // handle array case
      // TODO: remove when array is no longer accepted
      var field;
      for (var i = 0, len = obj.length; i < len; ++i) {
        field = obj[i][0];
        if (headers[field] !== undefined) {
          obj.push([field, headers[field]]);
        }
      }
      headers = obj;

    } else {
      // handle object case
      var keys = Object.keys(obj);
      for (var i = 0; i < keys.length; i++) {
        var k = keys[i];
        if (k) headers[k] = obj[k];
      }
    }
  } else if (this._headers) {
    // only progressive api is used
    headers = this._renderHeaders();
  } else {
    // only writeHead() called
    headers = obj;
  }

  var statusLine = 'HTTP/1.1 ' + statusCode.toString() + ' ' +
                   reasonPhrase + CRLF;

  if (statusCode === 204 || statusCode === 304 ||
      (100 <= statusCode && statusCode <= 199)) {
    // RFC 2616, 10.2.5:
    // The 204 response MUST NOT include a message-body, and thus is always
    // terminated by the first empty line after the header fields.
    // RFC 2616, 10.3.5:
    // The 304 response MUST NOT contain a message-body, and thus is always
    // terminated by the first empty line after the header fields.
    // RFC 2616, 10.1 Informational 1xx:
    // This class of status code indicates a provisional response,
    // consisting only of the Status-Line and optional headers, and is
    // terminated by an empty line.
    this._hasBody = false;
  }

  // don't keep alive connections where the client expects 100 Continue
  // but we sent a final status; they may put extra bytes on the wire.
  if (this._expect_continue && !this._sent100) {
    this.shouldKeepAlive = false;
  }

  this._storeHeader(statusLine, headers);
};

ServerResponse.prototype.writeHeader = function() {
  this.writeHead.apply(this, arguments);
};


var agent = require('_http_agent');

var Agent = exports.Agent = agent.Agent;
var globalAgent = exports.globalAgent = agent.globalAgent;


function ClientRequest(options, cb) {
  var self = this;
  OutgoingMessage.call(self);

  self.agent = options.agent === undefined ? globalAgent : options.agent;

  var defaultPort = options.defaultPort || 80;

  var port = options.port || defaultPort;
  var host = options.hostname || options.host || 'localhost';

  if (options.setHost === undefined) {
    var setHost = true;
  }

  self.socketPath = options.socketPath;

  var method = self.method = (options.method || 'GET').toUpperCase();
  self.path = options.path || '/';
  if (cb) {
    self.once('response', cb);
  }

  if (!Array.isArray(options.headers)) {
    if (options.headers) {
      var keys = Object.keys(options.headers);
      for (var i = 0, l = keys.length; i < l; i++) {
        var key = keys[i];
        self.setHeader(key, options.headers[key]);
      }
    }
    if (host && !this.getHeader('host') && setHost) {
      var hostHeader = host;
      if (port && +port !== defaultPort) {
        hostHeader += ':' + port;
      }
      this.setHeader('Host', hostHeader);
    }
  }

  if (options.auth && !this.getHeader('Authorization')) {
    //basic auth
    this.setHeader('Authorization', 'Basic ' +
                   new Buffer(options.auth).toString('base64'));
  }

  if (method === 'GET' || method === 'HEAD' || method === 'CONNECT') {
    self.useChunkedEncodingByDefault = false;
  } else {
    self.useChunkedEncodingByDefault = true;
  }

  if (Array.isArray(options.headers)) {
    self._storeHeader(self.method + ' ' + self.path + ' HTTP/1.1\r\n',
                      options.headers);
  } else if (self.getHeader('expect')) {
    self._storeHeader(self.method + ' ' + self.path + ' HTTP/1.1\r\n',
                      self._renderHeaders());
  }
  if (self.socketPath) {
    self._last = true;
    self.shouldKeepAlive = false;
    if (options.createConnection) {
      self.onSocket(options.createConnection(self.socketPath));
    } else {
      self.onSocket(net.createConnection(self.socketPath));
    }
  } else if (self.agent) {
    // If there is an agent we should default to Connection:keep-alive.
    self._last = false;
    self.shouldKeepAlive = true;
    self.agent.addRequest(self, host, port, options.localAddress);
  } else {
    // No agent, default to Connection:close.
    self._last = true;
    self.shouldKeepAlive = false;
    if (options.createConnection) {
      options.port = port;
      options.host = host;
      var conn = options.createConnection(options);
    } else {
      var conn = net.createConnection({
        port: port,
        host: host,
        localAddress: options.localAddress
      });
    }
    self.onSocket(conn);
  }

  self._deferToConnect(null, null, function() {
    self._flush();
    self = null;
  });

}
util.inherits(ClientRequest, OutgoingMessage);

exports.ClientRequest = ClientRequest;

ClientRequest.prototype._implicitHeader = function() {
  this._storeHeader(this.method + ' ' + this.path + ' HTTP/1.1\r\n',
                    this._renderHeaders());
};

ClientRequest.prototype.abort = function() {
  if (this.socket) {
    // in-progress
    this.socket.destroy();
  } else {
    // haven't been assigned a socket yet.
    // this could be more efficient, it could
    // remove itself from the pending requests
    this._deferToConnect('destroy', []);
  }
};


function createHangUpError() {
  var error = new Error('socket hang up');
  error.code = 'ECONNRESET';
  return error;
}


function socketCloseListener() {
  var socket = this;
  var parser = socket.parser;
  var req = socket._httpMessage;
  debug('HTTP socket close');
  req.emit('close');
  if (req.res && req.res.readable) {
    // Socket closed before we emitted 'end' below.
    req.res.emit('aborted');
    var res = req.res;
    res.on('end', function() {
      res.emit('close');
    });
    res.push(null);
  } else if (!req.res && !req._hadError) {
    // This socket error fired before we started to
    // receive a response. The error needs to
    // fire on the request.
    req.emit('error', createHangUpError());
    req._hadError = true;
  }

  // Too bad.  That output wasn't getting written.
  // This is pretty terrible that it doesn't raise an error.
  // Fixed better in v0.10
  if (req.output)
    req.output.length = 0;
  if (req.outputEncodings)
    req.outputEncodings.length = 0;

  if (parser) {
    parser.finish();
    freeParser(parser, req);
  }
}

function socketErrorListener(err) {
  var socket = this;
  var parser = socket.parser;
  var req = socket._httpMessage;
  debug('HTTP SOCKET ERROR: ' + err.message + '\n' + err.stack);

  if (req) {
    req.emit('error', err);
    // For Safety. Some additional errors might fire later on
    // and we need to make sure we don't double-fire the error event.
    req._hadError = true;
  }

  if (parser) {
    parser.finish();
    freeParser(parser, req);
  }
  socket.destroy();
}

function socketOnEnd() {
  var socket = this;
  var req = this._httpMessage;
  var parser = this.parser;

  if (!req.res) {
    // If we don't have a response then we know that the socket
    // ended prematurely and we need to emit an error on the request.
    req.emit('error', createHangUpError());
    req._hadError = true;
  }
  if (parser) {
    parser.finish();
    freeParser(parser, req);
  }
  socket.destroy();
}

function socketOnData(d, start, end) {
  var socket = this;
  var req = this._httpMessage;
  var parser = this.parser;

  var ret = parser.execute(d, start, end - start);
  if (ret instanceof Error) {
    debug('parse error');
    freeParser(parser, req);
    socket.destroy();
    req.emit('error', ret);
    req._hadError = true;
  } else if (parser.incoming && parser.incoming.upgrade) {
    // Upgrade or CONNECT
    var bytesParsed = ret;
    var res = parser.incoming;
    req.res = res;

    socket.ondata = null;
    socket.onend = null;
    parser.finish();

    // This is start + byteParsed
    var bodyHead = d.slice(start + bytesParsed, end);

    var eventName = req.method === 'CONNECT' ? 'connect' : 'upgrade';
    if (EventEmitter.listenerCount(req, eventName) > 0) {
      req.upgradeOrConnect = true;

      // detach the socket
      socket.emit('agentRemove');
      socket.removeListener('close', socketCloseListener);
      socket.removeListener('error', socketErrorListener);

      req.emit(eventName, res, socket, bodyHead);
      req.emit('close');
    } else {
      // Got Upgrade header or CONNECT method, but have no handler.
      socket.destroy();
    }
    freeParser(parser, req);
  } else if (parser.incoming && parser.incoming.complete &&
             // When the status code is 100 (Continue), the server will
             // send a final response after this client sends a request
             // body. So, we must not free the parser.
             parser.incoming.statusCode !== 100) {
    freeParser(parser, req);
  }
}


// client
function parserOnIncomingClient(res, shouldKeepAlive) {
  var parser = this;
  var socket = this.socket;
  var req = socket._httpMessage;


  // propogate "domain" setting...
  if (req.domain && !res.domain) {
    debug('setting "res.domain"');
    res.domain = req.domain;
  }

  debug('AGENT incoming response!');

  if (req.res) {
    // We already have a response object, this means the server
    // sent a double response.
    socket.destroy();
    return;
  }
  req.res = res;

  // Responses to CONNECT request is handled as Upgrade.
  if (req.method === 'CONNECT') {
    res.upgrade = true;
    return true; // skip body
  }

  // Responses to HEAD requests are crazy.
  // HEAD responses aren't allowed to have an entity-body
  // but *can* have a content-length which actually corresponds
  // to the content-length of the entity-body had the request
  // been a GET.
  var isHeadResponse = req.method == 'HEAD';
  debug('AGENT isHeadResponse ' + isHeadResponse);

  if (res.statusCode == 100) {
    // restart the parser, as this is a continue message.
    delete req.res; // Clear res so that we don't hit double-responses.
    req.emit('continue');
    return true;
  }

  if (req.shouldKeepAlive && !shouldKeepAlive && !req.upgradeOrConnect) {
    // Server MUST respond with Connection:keep-alive for us to enable it.
    // If we've been upgraded (via WebSockets) we also shouldn't try to
    // keep the connection open.
    req.shouldKeepAlive = false;
  }


  DTRACE_HTTP_CLIENT_RESPONSE(socket, req);
  COUNTER_HTTP_CLIENT_RESPONSE();
  req.res = res;
  res.req = req;

  // add our listener first, so that we guarantee socket cleanup
  res.on('end', responseOnEnd);
  var handled = req.emit('response', res);

  // If the user did not listen for the 'response' event, then they
  // can't possibly read the data, so we ._dump() it into the void
  // so that the socket doesn't hang there in a paused state.
  if (!handled)
    res._dump();

  return isHeadResponse;
}

// client
function responseOnEnd() {
  var res = this;
  var req = res.req;
  var socket = req.socket;

  if (!req.shouldKeepAlive) {
    if (socket.writable) {
      debug('AGENT socket.destroySoon()');
      socket.destroySoon();
    }
    assert(!socket.writable);
  } else {
    debug('AGENT socket keep-alive');
    if (req.timeoutCb) {
      socket.setTimeout(0, req.timeoutCb);
      req.timeoutCb = null;
    }
    socket.removeListener('close', socketCloseListener);
    socket.removeListener('error', socketErrorListener);
    // Mark this socket as available, AFTER user-added end
    // handlers have a chance to run.
    process.nextTick(function() {
      socket.emit('free');
    });
  }
}

ClientRequest.prototype.onSocket = function(socket) {
  var req = this;

  process.nextTick(function() {
    var parser = parsers.alloc();
    req.socket = socket;
    req.connection = socket;
    parser.reinitialize(HTTPParser.RESPONSE);
    parser.socket = socket;
    parser.incoming = null;
    req.parser = parser;

    socket.parser = parser;
    socket._httpMessage = req;

    // Setup "drain" propogation.
    httpSocketSetup(socket);

    // Propagate headers limit from request object to parser
    if (typeof req.maxHeadersCount === 'number') {
      parser.maxHeaderPairs = req.maxHeadersCount << 1;
    } else {
      // Set default value because parser may be reused from FreeList
      parser.maxHeaderPairs = 2000;
    }

    socket.on('error', socketErrorListener);
    socket.ondata = socketOnData;
    socket.onend = socketOnEnd;
    socket.on('close', socketCloseListener);
    parser.onIncoming = parserOnIncomingClient;
    req.emit('socket', socket);
  });

};

ClientRequest.prototype._deferToConnect = function(method, arguments_, cb) {
  // This function is for calls that need to happen once the socket is
  // connected and writable. It's an important promisy thing for all the socket
  // calls that happen either now (when a socket is assigned) or
  // in the future (when a socket gets assigned out of the pool and is
  // eventually writable).
  var self = this;
  var onSocket = function() {
    if (self.socket.writable) {
      if (method) {
        self.socket[method].apply(self.socket, arguments_);
      }
      if (cb) { cb(); }
    } else {
      self.socket.once('connect', function() {
        if (method) {
          self.socket[method].apply(self.socket, arguments_);
        }
        if (cb) { cb(); }
      });
    }
  }
  if (!self.socket) {
    self.once('socket', onSocket);
  } else {
    onSocket();
  }
};

ClientRequest.prototype.setTimeout = function(msecs, callback) {
  if (callback) this.once('timeout', callback);

  var self = this;
  function emitTimeout() {
    self.emit('timeout');
  }

  if (this.socket && this.socket.writable) {
    if (this.timeoutCb)
      this.socket.setTimeout(0, this.timeoutCb);
    this.timeoutCb = emitTimeout;
    this.socket.setTimeout(msecs, emitTimeout);
    return;
  }

  // Set timeoutCb so that it'll get cleaned up on request end
  this.timeoutCb = emitTimeout;
  if (this.socket) {
    var sock = this.socket;
    this.socket.once('connect', function() {
      sock.setTimeout(msecs, emitTimeout);
    });
    return;
  }

  this.once('socket', function(sock) {
    sock.setTimeout(msecs, emitTimeout);
  });
};

ClientRequest.prototype.setNoDelay = function() {
  this._deferToConnect('setNoDelay', arguments);
};
ClientRequest.prototype.setSocketKeepAlive = function() {
  this._deferToConnect('setKeepAlive', arguments);
};

ClientRequest.prototype.clearTimeout = function(cb) {
  this.setTimeout(0, cb);
};

exports.request = function(options, cb) {
  if (typeof options === 'string') {
    options = url.parse(options);
  } else if (options && options.path) {
    options = util._extend({}, options);
    options.path = encodeURI(options.path);
    // encodeURI() doesn't escape quotes while url.parse() does. Fix up.
    options.path = options.path.replace(/'/g, '%27');
  }

  if (options.protocol && options.protocol !== 'http:') {
    throw new Error('Protocol:' + options.protocol + ' not supported.');
  }

  return new ClientRequest(options, cb);
};

exports.get = function(options, cb) {
  var req = exports.request(options, cb);
  req.end();
  return req;
};


function ondrain() {
  if (this._httpMessage) this._httpMessage.emit('drain');
}


function httpSocketSetup(socket) {
  socket.removeListener('drain', ondrain);
  socket.on('drain', ondrain);
}


function Server(requestListener) {
  if (!(this instanceof Server)) return new Server(requestListener);
  net.Server.call(this, { allowHalfOpen: true });

  if (requestListener) {
    this.addListener('request', requestListener);
  }

  // Similar option to this. Too lazy to write my own docs.
  // http://www.squid-cache.org/Doc/config/half_closed_clients/
  // http://wiki.squid-cache.org/SquidFaq/InnerWorkings#What_is_a_half-closed_filedescriptor.3F
  this.httpAllowHalfOpen = false;

  this.addListener('connection', connectionListener);

  this.addListener('clientError', function(err, conn) {
    conn.destroy(err);
  });

  this.timeout = 2 * 60 * 1000;
}
util.inherits(Server, net.Server);


Server.prototype.setTimeout = function(msecs, callback) {
  this.timeout = msecs;
  if (callback)
    this.on('timeout', callback);
};


exports.Server = Server;


exports.createServer = function(requestListener) {
  return new Server(requestListener);
};


function connectionListener(socket) {
  var self = this;
  var outgoing = [];
  var incoming = [];

  function abortIncoming() {
    while (incoming.length) {
      var req = incoming.shift();
      req.emit('aborted');
      req.emit('close');
    }
    // abort socket._httpMessage ?
  }

  function serverSocketCloseListener() {
    debug('server socket close');
    // mark this parser as reusable
    if (this.parser)
      freeParser(this.parser);

    abortIncoming();
  }

  debug('SERVER new http connection');

  httpSocketSetup(socket);

  // If the user has added a listener to the server,
  // request, or response, then it's their responsibility.
  // otherwise, destroy on timeout by default
  if (self.timeout)
    socket.setTimeout(self.timeout);
  socket.on('timeout', function() {
    var req = socket.parser && socket.parser.incoming;
    var reqTimeout = req && !req.complete && req.emit('timeout', socket);
    var res = socket._httpMessage;
    var resTimeout = res && res.emit('timeout', socket);
    var serverTimeout = self.emit('timeout', socket);

    if (!reqTimeout && !resTimeout && !serverTimeout)
      socket.destroy();
  });

  var parser = parsers.alloc();
  parser.reinitialize(HTTPParser.REQUEST);
  parser.socket = socket;
  socket.parser = parser;
  parser.incoming = null;

  // Propagate headers limit from server instance to parser
  if (typeof this.maxHeadersCount === 'number') {
    parser.maxHeaderPairs = this.maxHeadersCount << 1;
  } else {
    // Set default value because parser may be reused from FreeList
    parser.maxHeaderPairs = 2000;
  }

  socket.addListener('error', function(e) {
    self.emit('clientError', e, this);
  });

  socket.ondata = function(d, start, end) {
    var ret = parser.execute(d, start, end - start);
    if (ret instanceof Error) {
      debug('parse error');
      socket.destroy(ret);
    } else if (parser.incoming && parser.incoming.upgrade) {
      // Upgrade or CONNECT
      var bytesParsed = ret;
      var req = parser.incoming;

      socket.ondata = null;
      socket.onend = null;
      socket.removeListener('close', serverSocketCloseListener);
      parser.finish();
      freeParser(parser, req);

      // This is start + byteParsed
      var bodyHead = d.slice(start + bytesParsed, end);

      var eventName = req.method === 'CONNECT' ? 'connect' : 'upgrade';
      if (EventEmitter.listenerCount(self, eventName) > 0) {
        self.emit(eventName, req, req.socket, bodyHead);
      } else {
        // Got upgrade header or CONNECT method, but have no handler.
        socket.destroy();
      }
    }
  };

  socket.onend = function() {
    var ret = parser.finish();

    if (ret instanceof Error) {
      debug('parse error');
      socket.destroy(ret);
      return;
    }

    if (!self.httpAllowHalfOpen) {
      abortIncoming();
      if (socket.writable) socket.end();
    } else if (outgoing.length) {
      outgoing[outgoing.length - 1]._last = true;
    } else if (socket._httpMessage) {
      socket._httpMessage._last = true;
    } else {
      if (socket.writable) socket.end();
    }
  };

  socket.addListener('close', serverSocketCloseListener);

  // The following callback is issued after the headers have been read on a
  // new message. In this callback we setup the response object and pass it
  // to the user.
  parser.onIncoming = function(req, shouldKeepAlive) {
    incoming.push(req);

    var res = new ServerResponse(req);

    res.shouldKeepAlive = shouldKeepAlive;
    DTRACE_HTTP_SERVER_REQUEST(req, socket);
    COUNTER_HTTP_SERVER_REQUEST();

    if (socket._httpMessage) {
      // There are already pending outgoing res, append.
      outgoing.push(res);
    } else {
      res.assignSocket(socket);
    }

    // When we're finished writing the response, check if this is the last
    // respose, if so destroy the socket.
    res.on('finish', function() {
      // Usually the first incoming element should be our request.  it may
      // be that in the case abortIncoming() was called that the incoming
      // array will be empty.
      assert(incoming.length == 0 || incoming[0] === req);

      incoming.shift();

      // if the user never called req.read(), and didn't pipe() or
      // .resume() or .on('data'), then we call req._dump() so that the
      // bytes will be pulled off the wire.
      if (!req._consuming)
        req._dump();

      res.detachSocket(socket);

      if (res._last) {
        socket.destroySoon();
      } else {
        // start sending the next message
        var m = outgoing.shift();
        if (m) {
          m.assignSocket(socket);
        }
      }
    });

    if (req.headers.expect !== undefined &&
        (req.httpVersionMajor == 1 && req.httpVersionMinor == 1) &&
        continueExpression.test(req.headers['expect'])) {
      res._expect_continue = true;
      if (EventEmitter.listenerCount(self, 'checkContinue') > 0) {
        self.emit('checkContinue', req, res);
      } else {
        res.writeContinue();
        self.emit('request', req, res);
      }
    } else {
      self.emit('request', req, res);
    }
    return false; // Not a HEAD response. (Not even a response!)
  };
}
exports._connectionListener = connectionListener;

// Legacy Interface

function Client(port, host) {
  if (!(this instanceof Client)) return new Client(port, host);
  EventEmitter.call(this);

  host = host || 'localhost';
  port = port || 80;
  this.host = host;
  this.port = port;
  this.agent = new Agent({ host: host, port: port, maxSockets: 1 });
}
util.inherits(Client, EventEmitter);
Client.prototype.request = function(method, path, headers) {
  var self = this;
  var options = {};
  options.host = self.host;
  options.port = self.port;
  if (method[0] === '/') {
    headers = path;
    path = method;
    method = 'GET';
  }
  options.method = method;
  options.path = path;
  options.headers = headers;
  options.agent = self.agent;
  var c = new ClientRequest(options);
  c.on('error', function(e) {
    self.emit('error', e);
  });
  // The old Client interface emitted 'end' on socket end.
  // This doesn't map to how we want things to operate in the future
  // but it will get removed when we remove this legacy interface.
  c.on('socket', function(s) {
    s.on('end', function() {
      if (self._decoder) {
        var ret = self._decoder.end();
        if (ret)
          self.emit('data', ret);
      }
      self.emit('end');
    });
  });
  return c;
};

exports.Client = util.deprecate(Client,
    'http.Client will be removed soon. Do not use it.');

exports.createClient = util.deprecate(function(port, host) {
  return new Client(port, host);
}, 'http.createClient is deprecated. Use `http.request` instead.');