Merge IO v2 branch to bleeding edge

sdk/lib/io/http_impl.dart

Index: sdk/lib/io/http_impl.dart
diff --git a/sdk/lib/io/http_impl.dart b/sdk/lib/io/http_impl.dart
index ede39a2418e518c3fc6b1ea5dba2681fca5107ac..1ed571eadda474cb4de614cdaa1f765847e3b1b9 100644
--- a/sdk/lib/io/http_impl.dart
+++ b/sdk/lib/io/http_impl.dart
@@ -4,520 +4,477 @@
 
 part of dart.io;
 
-// The close queue handles graceful closing of HTTP connections. When
-// a connection is added to the queue it will enter a wait state
-// waiting for all data written and possibly socket shutdown from
-// peer.
-class _CloseQueue {
-  _CloseQueue() : _q = new Set<_HttpConnectionBase>();
-
-  void add(_HttpConnectionBase connection) {
-    void closeIfDone() {
-      // When either the client has closed or all data has been
-      // written to the client we close the underlying socket
-      // completely.
-      if (connection._isWriteClosed || connection._isReadClosed) {
-        _q.remove(connection);
-        connection._socket.close();
-        if (connection.onClosed != null) connection.onClosed();
-      }
-    }
+class _HttpIncoming
+    extends Stream<List<int>> implements StreamSink<List<int>> {
+  final int _transferLength;
+  final Completer _dataCompleter = new Completer();
+  Stream<List<int>> _stream;
 
-    // If the connection is already fully closed don't insert it into
-    // the queue.
-    if (connection._isFullyClosed) {
-      connection._socket.close();
-      if (connection.onClosed != null) connection.onClosed();
-      return;
-    }
+  bool fullBodyRead = false;
 
-    connection._state |= _HttpConnectionBase.CLOSING;
-    _q.add(connection);
-
-    // If the output stream is not closed for writing, close it now and
-    // wait for callback when closed.
-    if (!connection._isWriteClosed) {
-      connection._socket.outputStream.close();
-      connection._socket.outputStream.onClosed = () {
-        connection._state |= _HttpConnectionBase.WRITE_CLOSED;
-        closeIfDone();
-      };
-    } else {
-      connection._socket.outputStream.onClosed = () { assert(false); };
-    }
+  // Common properties.
+  final _HttpHeaders headers;
+  bool upgraded = false;
 
-    // If the request is not already fully read wait for the socket to close.
-    // As the _isReadClosed state from the HTTP request processing indicate
-    // that the response has been parsed this does not necesarily mean tha
-    // the socket is closed.
-    if (!connection._isReadClosed) {
-      connection._socket.onClosed = () {
-        connection._state |= _HttpConnectionBase.READ_CLOSED;
-        closeIfDone();
-      };
-    }
+  // ClientResponse properties.
+  int statusCode;
+  String reasonPhrase;
+
+  // Request properties.
+  String method;
+  Uri uri;
 
-    // Ignore any data on a socket in the close queue.
-    connection._socket.onData = connection._socket.read;
+  // The transfer length if the length of the message body as it
+  // appears in the message (RFC 2616 section 4.4). This can be -1 if
+  // the length of the massage body is not known due to transfer
+  // codings.
+  int get transferLength => _transferLength;
 
-    // If an error occurs immediately close the socket.
-    connection._socket.onError = (e) {
-      connection._state |= _HttpConnectionBase.READ_CLOSED;
-      connection._state |= _HttpConnectionBase.WRITE_CLOSED;
-      closeIfDone();
-    };
+  _HttpIncoming(_HttpHeaders this.headers,
+                int this._transferLength,
+                Stream<List<int>> this._stream) {
   }
 
-  void shutdown() {
-    _q.forEach((_HttpConnectionBase connection) {
-      connection._socket.close();
-    });
+  StreamSubscription<List<int>> listen(void onData(List<int> event),
+                                       {void onError(AsyncError error),
+                                        void onDone(),
+                                        bool unsubscribeOnError}) {
+    return _stream.listen(onData,
+                          onError: onError,
+                          onDone: onDone,
+                          unsubscribeOnError: unsubscribeOnError);
   }
 
-  final Set<_HttpConnectionBase> _q;
+  // Is completed once all data have been received.
+  Future get dataDone => _dataCompleter.future;
+
+  void close() {
+    fullBodyRead = true;
+    _dataCompleter.complete();
+  }
 }
 
+class _HttpInboundMessage extends Stream<List<int>> {
+  final _HttpIncoming _incoming;
+  List<Cookie> _cookies;
 
-class _HttpRequestResponseBase {
-  static const int START = 0;
-  static const int HEADER_SENT = 1;
-  static const int DONE = 2;
-  static const int UPGRADED = 3;
+  _HttpInboundMessage(_HttpIncoming this._incoming);
 
-  _HttpRequestResponseBase(_HttpConnectionBase this._httpConnection)
-      : _state = START, _headResponse = false;
+  List<Cookie> get cookies {
+    if (_cookies != null) return _cookies;
+    return _cookies = headers._parseCookies();
+  }
 
-  int get contentLength => _headers.contentLength;
-  HttpHeaders get headers => _headers;
+  HttpHeaders get headers => _incoming.headers;
+  String get protocolVersion => headers.protocolVersion;
+  int get contentLength => headers.contentLength;
+  bool get persistentConnection => headers.persistentConnection;
+}
 
-  bool get persistentConnection {
-    List<String> connection = headers[HttpHeaders.CONNECTION];
-    if (_protocolVersion == "1.1") {
-      if (connection == null) return true;
-      return !headers[HttpHeaders.CONNECTION].any(
-          (value) => value.toLowerCase() == "close");
-    } else {
-      if (connection == null) return false;
-      return headers[HttpHeaders.CONNECTION].any(
-          (value) => value.toLowerCase() == "keep-alive");
-    }
-  }
 
-  X509Certificate get certificate {
-    var socket = _httpConnection._socket as SecureSocket;
-    return socket == null ? socket : socket.peerCertificate;
-  }
+class _HttpRequest extends _HttpInboundMessage implements HttpRequest {
+  final HttpResponse response;
 
-  void set persistentConnection(bool persistentConnection) {
-    if (_outputStream != null) throw new HttpException("Header already sent");
+  // Lazy initialized parsed query parameters.
+  Map<String, String> _queryParameters;
 
-    // Determine the value of the "Connection" header.
-    headers.remove(HttpHeaders.CONNECTION, "close");
-    headers.remove(HttpHeaders.CONNECTION, "keep-alive");
-    if (_protocolVersion == "1.1" && !persistentConnection) {
-      headers.add(HttpHeaders.CONNECTION, "close");
-    } else if (_protocolVersion == "1.0" && persistentConnection) {
-      headers.add(HttpHeaders.CONNECTION, "keep-alive");
-    }
-  }
+  final _HttpServer _httpServer;
 
+  final _HttpConnection _httpConnection;
 
-  bool _write(List<int> data, bool copyBuffer) {
-    if (_headResponse) return true;
-    _ensureHeadersSent();
-    bool allWritten = true;
-    if (data.length > 0) {
-      if (_headers.chunkedTransferEncoding) {
-        // Write chunk size if transfer encoding is chunked.
-        _writeHexString(data.length);
-        _writeCRLF();
-        _httpConnection._write(data, copyBuffer);
-        allWritten = _writeCRLF();
-      } else {
-        _updateContentLength(data.length);
-        allWritten = _httpConnection._write(data, copyBuffer);
-      }
-    }
-    return allWritten;
-  }
-
-  bool _writeList(List<int> data, int offset, int count) {
-    if (_headResponse) return true;
-    _ensureHeadersSent();
-    bool allWritten = true;
-    if (count > 0) {
-      if (_headers.chunkedTransferEncoding) {
-        // Write chunk size if transfer encoding is chunked.
-        _writeHexString(count);
-        _writeCRLF();
-        _httpConnection._writeFrom(data, offset, count);
-        allWritten = _writeCRLF();
-      } else {
-        _updateContentLength(count);
-        allWritten = _httpConnection._writeFrom(data, offset, count);
-      }
-    }
-    return allWritten;
-  }
+  HttpSession _session;
 
-  bool _writeDone() {
-    bool allWritten = true;
-    if (_headers.chunkedTransferEncoding) {
-      // Terminate the content if transfer encoding is chunked.
-      allWritten = _httpConnection._write(_Const.END_CHUNKED);
-    } else {
-      if (!_headResponse && _bodyBytesWritten < _headers.contentLength) {
-        throw new HttpException("Sending less than specified content length");
+  _HttpRequest(_HttpResponse this.response,
+               _HttpIncoming _incoming,
+               _HttpServer this._httpServer,
+               _HttpConnection this._httpConnection)
+      : super(_incoming) {
+    response.headers.persistentConnection = headers.persistentConnection;
+
+    if (_httpServer._sessionManagerInstance != null) {
+      // Map to session if exists.
+      var sessionId = cookies.reduce(null, (last, cookie) {
+        if (last != null) return last;
+        return cookie.name.toUpperCase() == _DART_SESSION_ID ?
+            cookie.value : null;
+      });
+      if (sessionId != null) {
+        _session = _httpServer._sessionManager.getSession(sessionId);
+        if (_session != null) {
+          _session._markSeen();
+        }
       }
-      assert(_headResponse || _bodyBytesWritten == _headers.contentLength);
     }
-    return allWritten;
   }
 
-  bool _writeHeaders() {
-    _headers._write(_httpConnection);
-    // Terminate header.
-    return _writeCRLF();
+  StreamSubscription<List<int>> listen(void onData(List<int> event),
+                                       {void onError(AsyncError error),
+                                        void onDone(),
+                                        bool unsubscribeOnError}) {
+    return _incoming.listen(onData,
+                            onError: onError,
+                            onDone: onDone,
+                            unsubscribeOnError: unsubscribeOnError);
   }
 
-  bool _writeHexString(int x) {
-    final List<int> hexDigits = [0x30, 0x31, 0x32, 0x33, 0x34,
-                                 0x35, 0x36, 0x37, 0x38, 0x39,
-                                 0x41, 0x42, 0x43, 0x44, 0x45, 0x46];
-    List<int> hex = new Uint8List(10);
-    int index = hex.length;
-    while (x > 0) {
-      index--;
-      hex[index] = hexDigits[x % 16];
-      x = x >> 4;
+  Map<String, String> get queryParameters {
+    if (_queryParameters == null) {
+      _queryParameters = _HttpUtils.splitQueryString(uri.query);
     }
-    return _httpConnection._writeFrom(hex, index, hex.length - index);
+    return _queryParameters;
   }
 
-  bool _writeCRLF() {
-    final CRLF = const [_CharCode.CR, _CharCode.LF];
-    return _httpConnection._write(CRLF);
-  }
+  Uri get uri => _incoming.uri;
 
-  bool _writeSP() {
-    final SP = const [_CharCode.SP];
-    return _httpConnection._write(SP);
-  }
+  String get method => _incoming.method;
 
-  void _ensureHeadersSent() {
-    // Ensure that headers are written.
-    if (_state == START) {
-      _writeHeader();
-    }
-  }
-
-  void _updateContentLength(int bytes) {
-    if (_bodyBytesWritten + bytes > _headers.contentLength) {
-      throw new HttpException("Writing more than specified content length");
+  HttpSession get session {
+    if (_session != null) {
+      // It's already mapped, use it.
+      return _session;
     }
-    _bodyBytesWritten += bytes;
+    // Create session, store it in connection, and return.
+    return _session = _httpServer._sessionManager.createSession();
   }
 
   HttpConnectionInfo get connectionInfo => _httpConnection.connectionInfo;
 
-  bool get _done => _state == DONE;
-
-  int _state;
-  bool _headResponse;
-
-  _HttpConnectionBase _httpConnection;
-  _HttpHeaders _headers;
-  List<Cookie> _cookies;
-  String _protocolVersion = "1.1";
-
-  // Number of body bytes written. This is only actual body data not
-  // including headers or chunk information of using chinked transfer
-  // encoding.
-  int _bodyBytesWritten = 0;
+  X509Certificate get certificate {
+    Socket socket = _httpConnection._socket;
+    if (socket is SecureSocket) return socket.peerCertificate;
+    return null;
+  }
 }
 
 
-// Parsed HTTP request providing information on the HTTP headers.
-class _HttpRequest extends _HttpRequestResponseBase implements HttpRequest {
-  _HttpRequest(_HttpConnection connection) : super(connection);
-
-  String get method => _method;
-  String get uri => _uri;
-  String get path => _path;
-  String get queryString => _queryString;
-  Map get queryParameters => _queryParameters;
-
-  List<Cookie> get cookies {
-    if (_cookies != null) return _cookies;
-
-    // Parse a Cookie header value according to the rules in RFC 6265.
-   void _parseCookieString(String s) {
-      int index = 0;
+class _HttpClientResponse
+    extends _HttpInboundMessage implements HttpClientResponse {
+  List<RedirectInfo> get redirects => _httpRequest._responseRedirects;
 
-      bool done() => index == s.length;
+  // The HttpClient this response belongs to.
+  final _HttpClient _httpClient;
 
-      void skipWS() {
-        while (!done()) {
-         if (s[index] != " " && s[index] != "\t") return;
-         index++;
-        }
-      }
+  // The HttpClientRequest of this response.
+  final _HttpClientRequest _httpRequest;
 
-      String parseName() {
-        int start = index;
-        while (!done()) {
-          if (s[index] == " " || s[index] == "\t" || s[index] == "=") break;
-          index++;
-        }
-        return s.substring(start, index).toLowerCase();
-      }
+  List<Cookie> _cookies;
 
-      String parseValue() {
-        int start = index;
-        while (!done()) {
-          if (s[index] == " " || s[index] == "\t" || s[index] == ";") break;
-          index++;
-        }
-        return s.substring(start, index).toLowerCase();
-      }
+  _HttpClientResponse(_HttpIncoming _incoming,
+                      _HttpClientRequest this._httpRequest,
+                      _HttpClient this._httpClient)
+      : super(_incoming);
 
-      void expect(String expected) {
-        if (done()) {
-          throw new HttpException("Failed to parse header value [$s]");
-        }
-        if (s[index] != expected) {
-          throw new HttpException("Failed to parse header value [$s]");
-        }
-        index++;
-      }
-
-      while (!done()) {
-        skipWS();
-        if (done()) return;
-        String name = parseName();
-        skipWS();
-        expect("=");
-        skipWS();
-        String value = parseValue();
-        _cookies.add(new _Cookie(name, value));
-        skipWS();
-        if (done()) return;
-        expect(";");
-      }
-    }
+  int get statusCode => _incoming.statusCode;
+  String get reasonPhrase => _incoming.reasonPhrase;
 
+  List<Cookie> get cookies {
+    if (_cookies != null) return _cookies;
     _cookies = new List<Cookie>();
-    List<String> headerValues = headers["cookie"];
-    if (headerValues != null) {
-      headerValues.forEach((headerValue) => _parseCookieString(headerValue));
+    List<String> values = headers["set-cookie"];
+    if (values != null) {
+      values.forEach((value) {
+        _cookies.add(new Cookie.fromSetCookieValue(value));
+      });
     }
     return _cookies;
   }
 
-  InputStream get inputStream {
-    if (_inputStream == null) {
-      _inputStream = new _HttpInputStream(this);
+  bool get isRedirect {
+    if (_httpRequest.method == "GET" || _httpRequest.method == "HEAD") {
+      return statusCode == HttpStatus.MOVED_PERMANENTLY ||
+             statusCode == HttpStatus.FOUND ||
+             statusCode == HttpStatus.SEE_OTHER ||
+             statusCode == HttpStatus.TEMPORARY_REDIRECT;
+    } else if (_httpRequest.method == "POST") {
+      return statusCode == HttpStatus.SEE_OTHER;
     }
-    return _inputStream;
+    return false;
   }
 
-  String get protocolVersion => _protocolVersion;
-
-  HttpSession session([init(HttpSession session)]) {
-    if (_session != null) {
-      // It's already mapped, use it.
-      return _session;
+  Future<HttpClientResponse> redirect([String method,
+                                       Uri url,
+                                       bool followLoops]) {
+    if (method == null) {
+      // Set method as defined by RFC 2616 section 10.3.4.
+      if (statusCode == HttpStatus.SEE_OTHER && _httpRequest.method == "POST") {
+        method = "GET";
+      } else {
+        method = _httpRequest.method;
+      }
     }
-    // Create session, store it in connection, and return.
-    var sessionManager = _httpConnection._server._sessionManager;
-    return _session = sessionManager.createSession(init);
-  }
-
-  void _onRequestReceived(String method,
-                          String uri,
-                          String version,
-                          _HttpHeaders headers) {
-    _method = method;
-    _uri = uri;
-    _parseRequestUri(uri);
-    _headers = headers;
-    if (_httpConnection._server._sessionManagerInstance != null) {
-      // Map to session if exists.
-      var sessionId = cookies.reduce(null, (last, cookie) {
-        if (last != null) return last;
-        return cookie.name.toUpperCase() == _DART_SESSION_ID ?
-            cookie.value : null;
-      });
-      if (sessionId != null) {
-        var sessionManager = _httpConnection._server._sessionManager;
-        _session = sessionManager.getSession(sessionId);
-        if (_session != null) {
-          _session._markSeen();
+    if (url == null) {
+      String location = headers.value(HttpHeaders.LOCATION);
+      if (location == null) {
+        throw new StateError("Response has no Location header for redirect");
+      }
+      url = Uri.parse(location);
+    }
+    if (followLoops != true) {
+      for (var redirect in redirects) {
+        if (redirect.location == url) {
+          return new Future.immediateError(
+              new RedirectLoopException(redirects));
         }
       }
     }
-
-    // Prepare for receiving data.
-    _buffer = new _BufferList();
+    return _httpClient._openUrlFromRequest(method, url, _httpRequest)
+        .then((request) {
+          request._responseRedirects.addAll(this.redirects);
+          request._responseRedirects.add(new _RedirectInfo(statusCode,
+                                                           method,
+                                                           url));
+          return request.close();
+        });
   }
 
-  void _onDataReceived(List<int> data) {
-    _buffer.add(data);
-    if (_inputStream != null) _inputStream._dataReceived();
+  StreamSubscription<List<int>> listen(void onData(List<int> event),
+                                       {void onError(AsyncError error),
+                                        void onDone(),
+                                        bool unsubscribeOnError}) {
+    return _incoming.listen(onData,
+                            onError: onError,
+                            onDone: onDone,
+                            unsubscribeOnError: unsubscribeOnError);
   }
 
-  void _onDataEnd() {
-    if (_inputStream != null) {
-      _inputStream._closeReceived();
-    } else {
-      inputStream._streamMarkedClosed = true;
-    }
+  Future<Socket> detachSocket() {
+    _httpClient._connectionClosed(_httpRequest._httpClientConnection);
+    return _httpRequest._httpClientConnection.detachSocket();
   }
 
-  // Escaped characters in uri are expected to have been parsed.
-  void _parseRequestUri(String uri) {
-    int position;
-    position = uri.indexOf("?", 0);
-    if (position == -1) {
-      _path = _HttpUtils.decodeUrlEncodedString(_uri);
-      _queryString = null;
-      _queryParameters = new Map();
-    } else {
-      _path = _HttpUtils.decodeUrlEncodedString(_uri.substring(0, position));
-      _queryString = _uri.substring(position + 1);
-      _queryParameters = _HttpUtils.splitQueryString(_queryString);
-    }
-  }
-
-  // Delegate functions for the HttpInputStream implementation.
-  int _streamAvailable() {
-    return _buffer.length;
-  }
+  HttpConnectionInfo get connectionInfo => _httpRequest.connectionInfo;
 
-  List<int> _streamRead(int bytesToRead) {
-    return _buffer.readBytes(bytesToRead);
+  bool get _shouldAuthenticate {
+    // Only try to authenticate if there is a challenge in the response.
+    List<String> challenge = headers[HttpHeaders.WWW_AUTHENTICATE];
+    return statusCode == HttpStatus.UNAUTHORIZED &&
+        challenge != null && challenge.length == 1;
   }
 
-  int _streamReadInto(List<int> buffer, int offset, int len) {
-    List<int> data = _buffer.readBytes(len);
-    buffer.setRange(offset, data.length, data);
-    return data.length;
-  }
+  Future<HttpClientResponse> _authenticate() {
+    Future<HttpClientResponse> retryWithCredentials(_Credentials cr) {
+      if (cr != null) {
+        // TODO(sgjesse): Support digest.
+        if (cr.scheme == _AuthenticationScheme.BASIC) {
+          // Drain body and retry.
+          return reduce(null, (x, y) {}).then((_) {
+              return _httpClient._openUrlFromRequest(_httpRequest.method,
+                                                     _httpRequest.uri,
+                                                     _httpRequest)
+                  .then((request) => request.close());
+            });
+        }
+      }
 
-  void _streamSetErrorHandler(callback(e)) {
-    _streamErrorHandler = callback;
+      // Fall through to here to perform normal response handling if
+      // there is no sensible authorization handling.
+      return new Future.immediate(this);
+    }
+
+    List<String> challenge = headers[HttpHeaders.WWW_AUTHENTICATE];
+    assert(challenge != null || challenge.length == 1);
+    _HeaderValue header =
+        new _HeaderValue.fromString(challenge[0], parameterSeparator: ",");
+    _AuthenticationScheme scheme =
+        new _AuthenticationScheme.fromString(header.value);
+    String realm = header.parameters["realm"];
+
+    // See if any credentials are available.
+    _Credentials cr = _httpClient._findCredentials(_httpRequest.uri, scheme);
+
+    if (cr != null && !cr.used) {
+      // If credentials found prepare for retrying the request.
+      return retryWithCredentials(cr);
+    }
+
+    // Ask for more credentials if none found or the one found has
+    // already been used. If it has already been used it must now be
+    // invalid and is removed.
+    if (cr != null) {
+      _httpClient._removeCredentials(cr);
+      cr = null;
+    }
+    if (_httpClient._authenticate != null) {
+      Future authComplete = _httpClient._authenticate(_httpRequest.uri,
+                                                      scheme.toString(),
+                                                      realm);
+      return authComplete.then((credsAvailable) {
+        if (credsAvailable) {
+          cr = _httpClient._findCredentials(_httpRequest.uri, scheme);
+          return retryWithCredentials(cr);
+        } else {
+          // No credentials available, complete with original response.
+          return this;
+        }
+      });
+    }
+    // No credentials were found and the callback was not set.
+    return new Future.immediate(this);
   }
-
-  String _method;
-  String _uri;
-  String _path;
-  String _queryString;
-  Map<String, String> _queryParameters;
-  _HttpInputStream _inputStream;
-  _BufferList _buffer;
-  Function _streamErrorHandler;
-  _HttpSession _session;
 }
 
 
-// HTTP response object for sending a HTTP response.
-class _HttpResponse extends _HttpRequestResponseBase implements HttpResponse {
-  _HttpResponse(_HttpConnection httpConnection)
-      : super(httpConnection),
-        _statusCode = HttpStatus.OK {
-    _headers = new _HttpHeaders();
-  }
+class _HttpOutboundMessage<T> extends IOSink {
+  // Used to mark when the body should be written. This is used for HEAD
+  // requests and in error handling.
+  bool _ignoreBody = false;
+
+  _HttpOutboundMessage(String protocolVersion, _HttpOutgoing outgoing)
+      : super(outgoing),
+        _outgoing = outgoing,
+        headers = new _HttpHeaders(protocolVersion);
 
+  int get contentLength => headers.contentLength;
   void set contentLength(int contentLength) {
-    if (_state >= _HttpRequestResponseBase.HEADER_SENT) {
-      throw new HttpException("Header already sent");
-    }
-    _headers.contentLength = contentLength;
+    headers.contentLength = contentLength;
   }
 
-  int get statusCode => _statusCode;
-  void set statusCode(int statusCode) {
-    if (_outputStream != null) throw new HttpException("Header already sent");
-    _statusCode = statusCode;
+  bool get persistentConnection => headers.persistentConnection;
+  bool set persistentConnection(bool p) {
+    headers.persistentConnection = p;
   }
 
-  String get reasonPhrase => _findReasonPhrase(_statusCode);
-  void set reasonPhrase(String reasonPhrase) {
-    if (_outputStream != null) throw new HttpException("Header already sent");
-    _reasonPhrase = reasonPhrase;
+  Future<T> consume(Stream<List<int>> stream) {
+    _writeHeaders();
+    if (_ignoreBody) return new Future.immediate(this);
+    if (_chunked) {
+      // Transform when chunked.
+      stream = stream.transform(new _ChunkedTransformer());
+    }
+    return super.consume(stream).then((_) => this);
   }
 
-  List<Cookie> get cookies {
-    if (_cookies == null) _cookies = new List<Cookie>();
-    return _cookies;
+  void add(List<int> data) {
+    _writeHeaders();
+    if (_ignoreBody) return;
+    if (_chunked) {
+      _ChunkedTransformer._addChunk(data, super.add);
+    } else {
+      super.add(data);
+    }
   }
 
-  OutputStream get outputStream {
-    if (_state >= _HttpRequestResponseBase.DONE) {
-      throw new HttpException("Response closed");
+  void close() {
+    if (!_headersWritten && !_ignoreBody && headers.chunkedTransferEncoding) {
+      // If no body was written, _ignoreBody is false (it's not a HEAD
+      // request) and the content-length is unspecified, set contentLength to 0.
+      headers.contentLength = 0;
     }
-    if (_outputStream == null) {
-      _outputStream = new _HttpOutputStream(this);
+    _writeHeaders();
+    if (!_ignoreBody) {
+      if (_chunked) {
+        _ChunkedTransformer._addChunk([], super.add);
+      }
     }
-    return _outputStream;
+    super.close();
   }
 
-  DetachedSocket detachSocket() {
-    if (_state >= _HttpRequestResponseBase.DONE) {
-      throw new HttpException("Response closed");
+  void _writeHeaders() {
+    if (_headersWritten) return;
+    bool _tmpIgnoreBody = _ignoreBody;
+    _ignoreBody = false;
+    _headersWritten = true;
+    _writeHeader();
+    _ignoreBody = _tmpIgnoreBody;
+    if (_ignoreBody) {
+      super.close();
+      return;
     }
-    // Ensure that headers are written.
-    if (_state == _HttpRequestResponseBase.START) {
-      _writeHeader();
+    _chunked = headers.chunkedTransferEncoding;
+    if (!_chunked) {
+      _outgoing.setTransferLength(headers.contentLength);
     }
-    _state = _HttpRequestResponseBase.UPGRADED;
-    // Ensure that any trailing data is written.
-    _writeDone();
-    // Indicate to the connection that the response handling is done.
-    return _httpConnection._detachSocket();
   }
 
-  // Delegate functions for the HttpOutputStream implementation.
-  bool _streamWrite(List<int> buffer, bool copyBuffer) {
-    if (_done) throw new HttpException("Response closed");
-    return _write(buffer, copyBuffer);
+  void _writeHeader();  // TODO(ajohnsen): Better name.
+
+  final _HttpHeaders headers;
+
+  final _HttpOutgoing _outgoing;
+  bool _headersWritten = false;
+  bool _chunked = false;
+}
+
+
+class _HttpResponse extends _HttpOutboundMessage<HttpResponse>
+    implements HttpResponse {
+  int statusCode = 200;
+  String _reasonPhrase;
+  List<Cookie> _cookies;
+  _HttpRequest _httpRequest;
+
+  _HttpResponse(String protocolVersion,
+                _HttpOutgoing _outgoing)
+      : super(protocolVersion, _outgoing);
+
+  List<Cookie> get cookies {
+    if (_cookies == null) _cookies = new List<Cookie>();
+    return _cookies;
   }
 
-  bool _streamWriteFrom(List<int> buffer, int offset, int len) {
-    if (_done) throw new HttpException("Response closed");
-    return _writeList(buffer, offset, len);
+  String get reasonPhrase => _findReasonPhrase(statusCode);
+  void set reasonPhrase(String reasonPhrase) {
+    if (_headersWritten) throw new StateError("Header already sent");
+    _reasonPhrase = reasonPhrase;
   }
 
-  void _streamFlush() {
-    _httpConnection._flush();
+  Future<Socket> detachSocket() {
+    if (_headersWritten) throw new StateError("Headers already sent");
+    _writeHeaders();
+    var future = _httpRequest._httpConnection.detachSocket();
+    // Close connection so the socket is 'free'.
+    close();
+    return future;
   }
 
-  void _streamClose() {
-    _ensureHeadersSent();
-    _state = _HttpRequestResponseBase.DONE;
-    // Stop tracking no pending write events.
-    _httpConnection._onNoPendingWrites = null;
-    // Ensure that any trailing data is written.
-    _writeDone();
-    // Indicate to the connection that the response handling is done.
-    _httpConnection._responseClosed();
-    if (_streamClosedHandler != null) {
-      Timer.run(_streamClosedHandler);
+  HttpConnectionInfo get connectionInfo => _httpRequest.connectionInfo;
+
+  void _writeHeader() {
+    writeSP() => add([_CharCode.SP]);
+    writeCRLF() => add([_CharCode.CR, _CharCode.LF]);
+
+    // Write status line.
+    if (headers.protocolVersion == "1.1") {
+      add(_Const.HTTP11);
+    } else {
+      add(_Const.HTTP10);
     }
-  }
+    writeSP();
+    addString(statusCode.toString());
+    writeSP();
+    addString(reasonPhrase);
+    writeCRLF();
 
-  void _streamSetNoPendingWriteHandler(callback()) {
-    if (_state != _HttpRequestResponseBase.DONE) {
-      _httpConnection._onNoPendingWrites = callback;
+    var session = _httpRequest._session;
+    if (session != null && !session._destroyed) {
+      // Mark as not new.
+      session._isNew = false;
+      // Make sure we only send the current session id.
+      bool found = false;
+      for (int i = 0; i < cookies.length; i++) {
+        if (cookies[i].name.toUpperCase() == _DART_SESSION_ID) {
+          cookies[i].value = session.id;
+          cookies[i].httpOnly = true;
+          found = true;
+          break;
+        }
+      }
+      if (!found) {
+        cookies.add(new Cookie(_DART_SESSION_ID, session.id)..httpOnly = true);
+      }
+    }
+    // Add all the cookies set to the headers.
+    if (_cookies != null) {
+      _cookies.forEach((cookie) {
+        headers.add("set-cookie", cookie);
+      });
     }
-  }
 
-  void _streamSetClosedHandler(callback()) {
-    _streamClosedHandler = callback;
-  }
+    headers._finalize();
 
-  void _streamSetErrorHandler(callback(e)) {
-    _streamErrorHandler = callback;
+    // Write headers.
+    headers._write(this);
+    writeCRLF();
   }
 
   String _findReasonPhrase(int statusCode) {
@@ -574,1231 +531,915 @@ class _HttpResponse extends _HttpRequestResponseBase implements HttpResponse {
       default: return "Status $statusCode";
     }
   }
-
-  bool _writeHeader() {
-    List<int> data;
-
-    // Write status line.
-    if (_protocolVersion == "1.1") {
-      _httpConnection._write(_Const.HTTP11);
-    } else {
-      _httpConnection._write(_Const.HTTP10);
-    }
-    _writeSP();
-    data = _statusCode.toString().charCodes;
-    _httpConnection._write(data);
-    _writeSP();
-    data = reasonPhrase.charCodes;
-    _httpConnection._write(data);
-    _writeCRLF();
-
-    var session = _httpConnection._request._session;
-    if (session != null && !session._destroyed) {
-      // Make sure we only send the current session id.
-      bool found = false;
-      for (int i = 0; i < cookies.length; i++) {
-        if (cookies[i].name.toUpperCase() == _DART_SESSION_ID) {
-          cookies[i].value = session.id;
-          cookies[i].httpOnly = true;
-          found = true;
-          break;
-        }
-      }
-      if (!found) {
-        cookies.add(new Cookie(_DART_SESSION_ID, session.id)..httpOnly = true);
-      }
-    }
-    // Add all the cookies set to the headers.
-    if (_cookies != null) {
-      _cookies.forEach((cookie) {
-        _headers.add("set-cookie", cookie);
-      });
-    }
-
-    // Write headers.
-    _headers._finalize(_protocolVersion);
-    bool allWritten = _writeHeaders();
-    _state = _HttpRequestResponseBase.HEADER_SENT;
-    return allWritten;
-  }
-
-  int _statusCode;  // Response status code.
-  String _reasonPhrase;  // Response reason phrase.
-  _HttpOutputStream _outputStream;
-  Function _streamClosedHandler;
-  Function _streamErrorHandler;
 }
 
 
-class _HttpInputStream extends _BaseDataInputStream implements InputStream {
-  _HttpInputStream(_HttpRequestResponseBase this._requestOrResponse) {
-    _checkScheduleCallbacks();
-  }
-
-  int available() {
-    return _requestOrResponse._streamAvailable();
-  }
-
-  void pipe(OutputStream output, {bool close: true}) {
-    _pipe(this, output, close: close);
-  }
-
-  List<int> _read(int bytesToRead) {
-    List<int> result = _requestOrResponse._streamRead(bytesToRead);
-    _checkScheduleCallbacks();
-    return result;
-  }
-
-  void set onError(void callback(e)) {
-    _requestOrResponse._streamSetErrorHandler(callback);
-  }
-
-  int _readInto(List<int> buffer, int offset, int len) {
-    int result = _requestOrResponse._streamReadInto(buffer, offset, len);
-    _checkScheduleCallbacks();
-    return result;
-  }
-
-  void _close() {
-    // TODO(sgjesse): Handle this.
-  }
-
-  void _dataReceived() {
-    super._dataReceived();
-  }
-
-  _HttpRequestResponseBase _requestOrResponse;
-}
-
-
-class _HttpOutputStream extends _BaseOutputStream implements OutputStream {
-  _HttpOutputStream(_HttpRequestResponseBase this._requestOrResponse);
-
-  bool write(List<int> buffer, [bool copyBuffer = true]) {
-    return _requestOrResponse._streamWrite(buffer, copyBuffer);
-  }
-
-  bool writeFrom(List<int> buffer, [int offset = 0, int len]) {
-    if (offset < 0 || offset >= buffer.length) throw new ArgumentError();
-    len = len != null ? len : buffer.length - offset;
-    if (len < 0) throw new ArgumentError();
-    return _requestOrResponse._streamWriteFrom(buffer, offset, len);
-  }
-
-  void flush() {
-    _requestOrResponse._streamFlush();
-  }
-
-  void close() {
-    _requestOrResponse._streamClose();
-  }
-
-  bool get closed => _requestOrResponse._done;
-
-  void destroy() {
-    throw "Not implemented";
-  }
-
-  void set onNoPendingWrites(void callback()) {
-    _requestOrResponse._streamSetNoPendingWriteHandler(callback);
-  }
-
-  void set onClosed(void callback()) {
-    _requestOrResponse._streamSetClosedHandler(callback);
-  }
-
-  void set onError(void callback(e)) {
-    _requestOrResponse._streamSetErrorHandler(callback);
-  }
-
-  _HttpRequestResponseBase _requestOrResponse;
-}
-
-
-abstract class _HttpConnectionBase {
-  static const int IDLE = 0;
-  static const int ACTIVE = 1;
-  static const int CLOSING = 2;
-  static const int REQUEST_DONE = 4;
-  static const int RESPONSE_DONE = 8;
-  static const int ALL_DONE = REQUEST_DONE | RESPONSE_DONE;
-  static const int READ_CLOSED = 16;
-  static const int WRITE_CLOSED = 32;
-  static const int FULLY_CLOSED = READ_CLOSED | WRITE_CLOSED;
-
-  _HttpConnectionBase() : hashCode = _nextHashCode {
-    _nextHashCode = (_nextHashCode + 1) & 0xFFFFFFF;
-  }
-
-  bool get _isIdle => (_state & ACTIVE) == 0;
-  bool get _isActive => (_state & ACTIVE) == ACTIVE;
-  bool get _isClosing => (_state & CLOSING) == CLOSING;
-  bool get _isRequestDone => (_state & REQUEST_DONE) == REQUEST_DONE;
-  bool get _isResponseDone => (_state & RESPONSE_DONE) == RESPONSE_DONE;
-  bool get _isAllDone => (_state & ALL_DONE) == ALL_DONE;
-  bool get _isReadClosed => (_state & READ_CLOSED) == READ_CLOSED;
-  bool get _isWriteClosed => (_state & WRITE_CLOSED) == WRITE_CLOSED;
-  bool get _isFullyClosed => (_state & FULLY_CLOSED) == FULLY_CLOSED;
-
-  void _connectionEstablished(Socket socket) {
-    _socket = socket;
-    // Register handlers for socket events. All socket events are
-    // passed to the HTTP parser.
-    _socket.onData = () {
-      List<int> buffer = _socket.read();
-      if (buffer != null) {
-        _httpParser.streamData(buffer);
-      }
-    };
-    _socket.onClosed = _httpParser.streamDone;
-    _socket.onError = _httpParser.streamError;
-    _socket.outputStream.onError = _httpParser.streamError;
-  }
-
-  bool _write(List<int> data, [bool copyBuffer = false]);
-  bool _writeFrom(List<int> buffer, [int offset, int len]);
-  bool _flush();
-  bool _close();
-  bool _destroy();
-  DetachedSocket _detachSocket();
-
-  HttpConnectionInfo get connectionInfo {
-    if (_socket == null) return null;
-    try {
-      _HttpConnectionInfo info = new _HttpConnectionInfo();
-      info.remoteHost = _socket.remoteHost;
-      info.remotePort = _socket.remotePort;
-      info.localPort = _socket.port;
-      return info;
-    } catch (e) { }
-    return null;
-  }
-
-  void set _onNoPendingWrites(void callback()) {
-    _socket.outputStream.onNoPendingWrites = callback;
-  }
-
-  int _state = IDLE;
+class _HttpClientRequest extends _HttpOutboundMessage<HttpClientRequest>
+    implements HttpClientRequest {
+  final String method;
+  final Uri uri;
+  final List<Cookie> cookies = new List<Cookie>();
 
-  Socket _socket;
-  _HttpParser _httpParser;
+  // The HttpClient this request belongs to.
+  final _HttpClient _httpClient;
+  final _HttpClientConnection _httpClientConnection;
 
-  // Callbacks.
-  Function onDetach;
-  Function onClosed;
+  final Completer<HttpClientResponse> _responseCompleter
+      = new Completer<HttpClientResponse>();
 
-  // Hash code for HTTP connection. Currently this is just a counter.
-  final int hashCode;
-  static int _nextHashCode = 0;
-}
+  final bool _usingProxy;
 
+  // TODO(ajohnsen): Get default value from client?
+  bool _followRedirects = true;
 
-// HTTP server connection over a socket.
-class _HttpConnection extends _HttpConnectionBase {
-  _HttpConnection(HttpServer this._server) {
-    _httpParser = new _HttpParser.requestParser();
-    // Register HTTP parser callbacks.
-    _httpParser.requestStart = _onRequestReceived;
-    _httpParser.dataReceived = _onDataReceived;
-    _httpParser.dataEnd = _onDataEnd;
-    _httpParser.error = _onError;
-    _httpParser.closed = _onClosed;
-    _httpParser.responseStart = (statusCode, reasonPhrase, version) {
-      assert(false);
-    };
-  }
-
-  void _bufferData(List<int> data, [bool copyBuffer = false]) {
-    if (_buffer == null) _buffer = new _BufferList();
-    if (copyBuffer) data = data.getRange(0, data.length);
-    _buffer.add(data);
-  }
-
-  void _writeBufferedResponse() {
-    if (_buffer != null) {
-      while (!_buffer.isEmpty) {
-        var data = _buffer.first;
-        _socket.outputStream.write(data, false);
-        _buffer.removeBytes(data.length);
-      }
-      _buffer = null;
-    }
-  }
+  int _maxRedirects = 5;
 
-  bool _write(List<int> data, [bool copyBuffer = false]) {
-    if (_isRequestDone || !_hasBody || _httpParser.upgrade) {
-      return _socket.outputStream.write(data, copyBuffer);
-    } else {
-      _bufferData(data, copyBuffer);
-      return false;
-    }
-  }
+  List<RedirectInfo> _responseRedirects = [];
 
-  bool _writeFrom(List<int> data, [int offset, int len]) {
-    if (_isRequestDone || !_hasBody || _httpParser.upgrade) {
-      return _socket.outputStream.writeFrom(data, offset, len);
-    } else {
-      if (offset == null) offset = 0;
-      if (len == null) len = buffer.length - offset;
-      _bufferData(data.getRange(offset, len), false);
-      return false;
+  _HttpClientRequest(_HttpOutgoing outgoing,
+                     Uri this.uri,
+                     String this.method,
+                     bool this._usingProxy,
+                     _HttpClient this._httpClient,
+                     _HttpClientConnection this._httpClientConnection)
+      : super("1.1", outgoing) {
+    // GET and HEAD have 'content-length: 0' by default.
+    if (method == "GET" || method == "HEAD") {
+      contentLength = 0;
     }
   }
 
-  bool _flush() {
-    _socket.outputStream.flush();
-  }
-
-  bool _close() {
-    _socket.outputStream.close();
-  }
+  Future<HttpClientResponse> get response => _responseCompleter.future;
 
-  bool _destroy() {
-    _socket.close();
+  Future<HttpClientResponse> close() {
+    super.close();
+    return response;
   }
 
-  void _onClosed() {
-    _state |= _HttpConnectionBase.READ_CLOSED;
-    _checkDone();
+  int get maxRedirects => _maxRedirects;
+  void set maxRedirects(int maxRedirects) {
+    if (_headersWritten) throw new StateError("Request already sent");
+    _maxRedirects = maxRedirects;
   }
 
-  DetachedSocket _detachSocket() {
-    _socket.onData = null;
-    _socket.onClosed = null;
-    _socket.onError = null;
-    _socket.outputStream.onNoPendingWrites = null;
-    _writeBufferedResponse();
-    Socket socket = _socket;
-    _socket = null;
-    if (onDetach != null) onDetach();
-    return new _DetachedSocket(socket, _httpParser.readUnparsedData());
+  bool get followRedirects => _followRedirects;
+  void set followRedirects(bool followRedirects) {
+    if (_headersWritten) throw new StateError("Request already sent");
+    _followRedirects = followRedirects;
   }
 
-  void _onError(e) {
-    // Don't report errors for a request parser when HTTP parser is in
-    // idle state. Clients can close the connection and cause a
-    // connection reset by peer error which is OK.
-    _onClosed();
-    if (_state == _HttpConnectionBase.IDLE) return;
+  HttpConnectionInfo get connectionInfo => _httpClientConnection.connectionInfo;
 
-    // Propagate the error to the streams.
-    if (_request != null &&
-        !_isRequestDone &&
-        _request._streamErrorHandler != null) {
-      _request._streamErrorHandler(e);
-    } else if (_response != null &&
-        !_isResponseDone &&
-        _response._streamErrorHandler != null) {
-      _response._streamErrorHandler(e);
-    } else {
-      onError(e);
-    }
-    if (_socket != null) _socket.close();
-  }
-
-  void _onRequestReceived(String method,
-                          String uri,
-                          String version,
-                          _HttpHeaders headers,
-                          bool hasBody) {
-    _state = _HttpConnectionBase.ACTIVE;
-    // Create new request and response objects for this request.
-    _request = new _HttpRequest(this);
-    _response = new _HttpResponse(this);
-    _request._onRequestReceived(method, uri, version, headers);
-    _request._protocolVersion = version;
-    _response._protocolVersion = version;
-    _response._headResponse = method == "HEAD";
-    _response.persistentConnection = _httpParser.persistentConnection;
-    _hasBody = hasBody;
-    if (onRequestReceived != null) {
-      onRequestReceived(_request, _response);
-    }
-    _checkDone();
-  }
-
-  void _onDataReceived(List<int> data) {
-    _request._onDataReceived(data);
-    _checkDone();
-  }
-
-  void _checkDone() {
-    if (_isReadClosed) {
-      // If the client closes the conversation is ended.
-      _server._closeQueue.add(this);
-    } else if (_isAllDone) {
-      // If we are done writing the response, and the connection is
-      // not persistent, we must close. Also if using HTTP 1.0 and the
-      // content length was not known we must close to indicate end of
-      // body.
-      bool close =
-          !_response.persistentConnection ||
-          (_response._protocolVersion == "1.0" && _response.contentLength < 0);
-      _request = null;
-      _response = null;
-      if (close) {
-        _httpParser.cancel();
-        _server._closeQueue.add(this);
+  void _onIncoming(_HttpIncoming incoming) {
+    var response = new _HttpClientResponse(incoming,
+                                           this,
+                                          _httpClient);
+    Future<HttpClientResponse> future;
+    if (followRedirects && response.isRedirect) {
+      if (response.redirects.length < maxRedirects) {
+        // Redirect and drain response.
+        future = response.reduce(null, (x, y) {})
+          .then((_) => response.redirect());
       } else {
-        _state = _HttpConnectionBase.IDLE;
-      }
-    } else if (_isResponseDone && _hasBody) {
-      // If the response is closed before the request is fully read
-      // close this connection. If there is buffered output
-      // (e.g. error response for invalid request where the server did
-      // not care to read the request body) this is send.
-      assert(!_isRequestDone);
-      _writeBufferedResponse();
-      _httpParser.cancel();
-      _server._closeQueue.add(this);
-    }
-  }
-
-  void _onDataEnd(bool close) {
-    // Start sending queued response if any.
-    _state |= _HttpConnectionBase.REQUEST_DONE;
-    _writeBufferedResponse();
-    _request._onDataEnd();
-    _checkDone();
-  }
-
-  void _responseClosed() {
-    _state |= _HttpConnectionBase.RESPONSE_DONE;
-  }
-
-  HttpServer _server;
-  HttpRequest _request;
-  HttpResponse _response;
-  bool _hasBody = false;
-
-  // Buffer for data written before full response has been processed.
-  _BufferList _buffer;
-
-  // Callbacks.
-  Function onRequestReceived;
-  Function onError;
-}
-
-
-class _RequestHandlerRegistration {
-  _RequestHandlerRegistration(Function this._matcher, Function this._handler);
-  Function _matcher;
-  Function _handler;
-}
-
-// HTTP server waiting for socket connections. The connections are
-// managed by the server and as requests are received the request.
-// HTTPS connections are also supported, if the _HttpServer.httpsServer
-// constructor is used and a certificate name is provided in listen,
-// or a SecureServerSocket is provided to listenOn.
-class _HttpServer implements HttpServer, HttpsServer {
-  _HttpServer() : this._internal(isSecure: false);
-
-  _HttpServer.httpsServer() : this._internal(isSecure: true);
-
-  _HttpServer._internal({ bool isSecure: false })
-      : _secure = isSecure,
-        _connections = new Set<_HttpConnection>(),
-        _handlers = new List<_RequestHandlerRegistration>(),
-        _closeQueue = new _CloseQueue();
-
-  void listen(String host,
-              int port,
-              {int backlog: 128,
-               String certificate_name,
-               bool requestClientCertificate: false}) {
-    if (_secure) {
-      listenOn(new SecureServerSocket(
-          host,
-          port,
-          backlog,
-          certificate_name,
-          requestClientCertificate: requestClientCertificate));
-    } else {
-      listenOn(new ServerSocket(host, port, backlog));
-    }
-    _closeServer = true;
-  }
-
-  void listenOn(ServerSocket serverSocket) {
-    if (_secure && serverSocket is! SecureServerSocket) {
-        throw new HttpException(
-            'HttpsServer.listenOn was called with non-secure server socket');
-    } else if (!_secure && serverSocket is SecureServerSocket) {
-        throw new HttpException(
-            'HttpServer.listenOn was called with a secure server socket');
-    }
-    void onConnection(Socket socket) {
-      // Accept the client connection.
-      _HttpConnection connection = new _HttpConnection(this);
-      connection._connectionEstablished(socket);
-      _connections.add(connection);
-      connection.onRequestReceived = _handleRequest;
-      connection.onClosed = () => _connections.remove(connection);
-      connection.onDetach = () => _connections.remove(connection);
-      connection.onError = (e) {
-        _connections.remove(connection);
-        if (_onError != null) {
-          _onError(e);
-        } else {
-          throw(e);
-        }
-      };
-    }
-    serverSocket.onConnection = onConnection;
-    _server = serverSocket;
-    _closeServer = false;
-  }
-
-  addRequestHandler(bool matcher(HttpRequest request),
-                    void handler(HttpRequest request, HttpResponse response)) {
-    _handlers.add(new _RequestHandlerRegistration(matcher, handler));
-  }
-
-  void set defaultRequestHandler(
-      void handler(HttpRequest request, HttpResponse response)) {
-    _defaultHandler = handler;
-  }
-
-  void close() {
-    _closeQueue.shutdown();
-    if (_sessionManagerInstance != null) {
-      _sessionManagerInstance.close();
-      _sessionManagerInstance = null;
-    }
-    if (_server != null && _closeServer) {
-      _server.close();
-    }
-    _server = null;
-    for (_HttpConnection connection in _connections) {
-      connection._destroy();
-    }
-    _connections.clear();
-  }
-
-  int get port {
-    if (_server == null) {
-      throw new HttpException("The HttpServer is not listening on a port.");
-    }
-    return _server.port;
-  }
-
-  void set onError(void callback(e)) {
-    _onError = callback;
-  }
-
-  set sessionTimeout(int timeout) {
-    _sessionManager.sessionTimeout = timeout;
-  }
-
-  void _handleRequest(HttpRequest request, HttpResponse response) {
-    for (int i = 0; i < _handlers.length; i++) {
-      if (_handlers[i]._matcher(request)) {
-        Function handler = _handlers[i]._handler;
-        try {
-          handler(request, response);
-        } catch (e) {
-          if (_onError != null) {
-            _onError(e);
-          } else {
-            throw e;
-          }
-        }
-        return;
+        // End with exception, too many redirects.
+        future = response.reduce(null, (x, y) {})
+            .then((_) => new Future.immediateError(
+                new RedirectLimitExceededException(response.redirects)));
       }
-    }
-
-    if (_defaultHandler != null) {
-      _defaultHandler(request, response);
+    } else if (response._shouldAuthenticate) {
+      future = response._authenticate();
     } else {
-      response.statusCode = HttpStatus.NOT_FOUND;
-      response.contentLength = 0;
-      response.outputStream.close();
-    }
-  }
-
-  _HttpSessionManager get _sessionManager {
-    // Lazy init.
-    if (_sessionManagerInstance == null) {
-      _sessionManagerInstance = new _HttpSessionManager();
-    }
-    return _sessionManagerInstance;
-  }
-
-  HttpConnectionsInfo connectionsInfo() {
-    HttpConnectionsInfo result = new HttpConnectionsInfo();
-    result.total = _connections.length;
-    _connections.forEach((_HttpConnection conn) {
-      if (conn._isActive) {
-        result.active++;
-      } else if (conn._isIdle) {
-        result.idle++;
-      } else {
-        assert(result._isClosing);
-        result.closing++;
-      }
-    });
-    return result;
-  }
-
-  ServerSocket _server;  // The server listen socket.
-  bool _closeServer = false;
-  bool _secure;
-  Set<_HttpConnection> _connections;  // Set of currently connected clients.
-  List<_RequestHandlerRegistration> _handlers;
-  Object _defaultHandler;
-  Function _onError;
-  _CloseQueue _closeQueue;
-  _HttpSessionManager _sessionManagerInstance;
-}
-
-
-class _HttpClientRequest
-    extends _HttpRequestResponseBase implements HttpClientRequest {
-  _HttpClientRequest(String this._method,
-                     Uri this._uri,
-                     _HttpClientConnection connection)
-      : super(connection) {
-    _headers = new _HttpHeaders();
-    _connection = connection;
-    // Default GET and HEAD requests to have no content.
-    if (_method == "GET" || _method == "HEAD") {
-      contentLength = 0;
-    }
-  }
-
-  void set contentLength(int contentLength) {
-    if (_state >= _HttpRequestResponseBase.HEADER_SENT) {
-      throw new HttpException("Header already sent");
-    }
-    _headers.contentLength = contentLength;
-  }
-
-  List<Cookie> get cookies {
-    if (_cookies == null) _cookies = new List<Cookie>();
-    return _cookies;
-  }
-
-  OutputStream get outputStream {
-    if (_done) throw new HttpException("Request closed");
-    if (_outputStream == null) {
-      _outputStream = new _HttpOutputStream(this);
-    }
-    return _outputStream;
-  }
-
-  // Delegate functions for the HttpOutputStream implementation.
-  bool _streamWrite(List<int> buffer, bool copyBuffer) {
-    if (_done) throw new HttpException("Request closed");
-    _emptyBody = _emptyBody && buffer.length == 0;
-    return _write(buffer, copyBuffer);
-  }
-
-  bool _streamWriteFrom(List<int> buffer, int offset, int len) {
-    if (_done) throw new HttpException("Request closed");
-    _emptyBody = _emptyBody && buffer.length == 0;
-    return _writeList(buffer, offset, len);
-  }
-
-  void _streamFlush() {
-    _httpConnection._flush();
-  }
-
-  void _streamClose() {
-    _ensureHeadersSent();
-    _state = _HttpRequestResponseBase.DONE;
-    // Stop tracking no pending write events.
-    _httpConnection._onNoPendingWrites = null;
-    // Ensure that any trailing data is written.
-    _writeDone();
-    _connection._requestClosed();
-    if (_streamClosedHandler != null) {
-      Timer.run(_streamClosedHandler);
-    }
-  }
-
-  void _streamSetNoPendingWriteHandler(callback()) {
-    if (_state != _HttpRequestResponseBase.DONE) {
-      _httpConnection._onNoPendingWrites = callback;
+      future = new Future<HttpClientResponse>.immediate(response);
     }
+    future.then(
+        (v) => _responseCompleter.complete(v),
+        onError: (e) {
+          _responseCompleter.completeError(e);
+        });
   }
 
-  void _streamSetClosedHandler(callback()) {
-    _streamClosedHandler = callback;
-  }
-
-  void _streamSetErrorHandler(callback(e)) {
-    _streamErrorHandler = callback;
+  void _onError(AsyncError error) {
+    _responseCompleter.completeError(error);
   }
 
   void _writeHeader() {
-    List<int> data;
+    writeSP() => add([_CharCode.SP]);
+    writeCRLF() => add([_CharCode.CR, _CharCode.LF]);
 
-    // Write request line.
-    data = _method.toString().charCodes;
-    _httpConnection._write(data);
-    _writeSP();
+    addString(method);
+    writeSP();
     // Send the path for direct connections and the whole URL for
     // proxy connections.
-    if (!_connection._usingProxy) {
-      String path = _uri.path;
+    if (!_usingProxy) {
+      String path = uri.path;
       if (path.length == 0) path = "/";
-      if (_uri.query != "") {
-        if (_uri.fragment != "") {
-          path = "${path}?${_uri.query}#${_uri.fragment}";
+      if (uri.query != "") {
+        if (uri.fragment != "") {
+          path = "${path}?${uri.query}#${uri.fragment}";
         } else {
-          path = "${path}?${_uri.query}";
+          path = "${path}?${uri.query}";
         }
       }
-      data = path.charCodes;
+      addString(path);
     } else {
-      data = _uri.toString().charCodes;
+      addString(uri.toString());
     }
-    _httpConnection._write(data);
-    _writeSP();
-    _httpConnection._write(_Const.HTTP11);
-    _writeCRLF();
+    writeSP();
+    add(_Const.HTTP11);
+    writeCRLF();
 
     // Add the cookies to the headers.
-    if (_cookies != null) {
+    if (!cookies.isEmpty) {
       StringBuffer sb = new StringBuffer();
-      for (int i = 0; i < _cookies.length; i++) {
+      for (int i = 0; i < cookies.length; i++) {
         if (i > 0) sb.add("; ");
-        sb.add(_cookies[i].name);
+        sb.add(cookies[i].name);
         sb.add("=");
-        sb.add(_cookies[i].value);
+        sb.add(cookies[i].value);
       }
-      _headers.add("cookie", sb.toString());
+      headers.add("cookie", sb.toString());
     }
 
+    headers._finalize();
+
     // Write headers.
-    _headers._finalize("1.1");
-    _writeHeaders();
-    _state = _HttpRequestResponseBase.HEADER_SENT;
+    headers._write(this);
+    writeCRLF();
   }
-
-  String _method;
-  Uri _uri;
-  _HttpClientConnection _connection;
-  _HttpOutputStream _outputStream;
-  Function _streamClosedHandler;
-  Function _streamErrorHandler;
-  bool _emptyBody = true;
 }
 
-class _HttpClientResponse
-    extends _HttpRequestResponseBase
-    implements HttpClientResponse {
-  _HttpClientResponse(_HttpClientConnection connection)
-      : super(connection) {
-    _connection = connection;
-  }
 
-  int get statusCode => _statusCode;
-  String get reasonPhrase => _reasonPhrase;
-
-  bool get isRedirect {
-    var method = _connection._request._method;
-    if (method == "GET" || method == "HEAD") {
-      return statusCode == HttpStatus.MOVED_PERMANENTLY ||
-             statusCode == HttpStatus.FOUND ||
-             statusCode == HttpStatus.SEE_OTHER ||
-             statusCode == HttpStatus.TEMPORARY_REDIRECT;
-    } else if (method == "POST") {
-      return statusCode == HttpStatus.SEE_OTHER;
+// Transformer that transforms data to HTTP Chunked Encoding.
+class _ChunkedTransformer implements StreamTransformer<List<int>, List<int>> {
+  final StreamController<List<int>> _controller
+      = new StreamController<List<int>>();
+
+  Stream<List<int>> bind(Stream<List<int>> stream) {
+    var subscription = stream.listen(
+        (data) {
+          if (data.length == 0) return;  // Avoid close on 0-bytes payload.
+          _addChunk(data, _controller.add);
+       },
+       onDone: () {
+          _addChunk([], _controller.add);
+          _controller.close();
+       });
+    return _controller.stream;
+  }
+
+  static void _addChunk(List<int> data, void add(List<int> data)) {
+    add(_chunkHeader(data.length));
+    if (data.length > 0) add(data);
+    add(_chunkFooter);
+  }
+
+  static List<int> _chunkHeader(int length) {
+    const hexDigits = const [0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37,
+                             0x38, 0x39, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46];
+    var header = [];
+    if (length == 0) {
+      header.add(hexDigits[length]);
+    } else {
+      while (length > 0) {
+        header.insertRange(0, 1, hexDigits[length % 16]);
+        length = length >> 4;
+      }
     }
-    return false;
+    header.add(_CharCode.CR);
+    header.add(_CharCode.LF);
+    return header;
   }
 
-  List<Cookie> get cookies {
-    if (_cookies != null) return _cookies;
-    _cookies = new List<Cookie>();
-    List<String> values = _headers["set-cookie"];
-    if (values != null) {
-      values.forEach((value) {
-        _cookies.add(new Cookie.fromSetCookieValue(value));
-      });
-    }
-    return _cookies;
-  }
+  // Footer is just a CRLF.
+  static List<int> get _chunkFooter => const [_CharCode.CR, _CharCode.LF];
+}
 
-  InputStream get inputStream {
-    if (_inputStream == null) {
-      _inputStream = new _HttpInputStream(this);
-    }
-    return _inputStream;
+
+// Transformer that invokes [_onDone] when completed.
+class _DoneTransformer implements StreamTransformer<List<int>, List<int>> {
+  final StreamController<List<int>> _controller
+      = new StreamController<List<int>>();
+  final Function _onDone;
+
+  _DoneTransformer(this._onDone);
+
+  Stream<List<int>> bind(Stream<List<int>> stream) {
+    var subscription = stream.listen(
+        _controller.add,
+        onError: _controller.signalError,
+        onDone: () {
+          _onDone();
+          _controller.close();
+        });
+    return _controller.stream;
   }
+}
 
-  void _onResponseReceived(int statusCode,
-                           String reasonPhrase,
-                           String version,
-                           _HttpHeaders headers,
-                           bool hasBody) {
-    _statusCode = statusCode;
-    _reasonPhrase = reasonPhrase;
-    _headers = headers;
-
-    // Prepare for receiving data.
-    _buffer = new _BufferList();
-    if (isRedirect && _connection.followRedirects) {
-      if (_connection._redirects == null ||
-          _connection._redirects.length < _connection.maxRedirects) {
-        // Check the location header.
-        List<String> location = headers[HttpHeaders.LOCATION];
-        if (location == null || location.length > 1) {
-           throw new RedirectException("Invalid redirect",
-                                       _connection._redirects);
-        }
-        // Check for redirect loop
-        if (_connection._redirects != null) {
-          Uri redirectUrl = Uri.parse(location[0]);
-          for (int i = 0; i < _connection._redirects.length; i++) {
-            if (_connection._redirects[i].location.toString() ==
-                redirectUrl.toString()) {
-              throw new RedirectLoopException(_connection._redirects);
+// Transformer that validates the data written.
+class _DataValidatorTransformer
+    implements StreamTransformer<List<int>, List<int>> {
+  final StreamController<List<int>> _controller
+      = new StreamController<List<int>>();
+  int _bytesWritten = 0;
+  Completer _completer = new Completer();
+
+  int expectedTransferLength;
+
+  _DataValidatorTransformer();
+
+  Future get validatorFuture => _completer.future;
+
+  Stream<List<int>> bind(Stream<List<int>> stream) {
+    var subscription;
+    subscription = stream.listen(
+        (data) {
+          if (expectedTransferLength != null) {
+            _bytesWritten += data.length;
+            if (_bytesWritten > expectedTransferLength) {
+              _controller.close();
+              subscription.cancel();
+              if (_completer != null) {
+                _completer.completeError(new HttpException(
+                    "Content size exceeds specified contentLength. "
+                    "$_bytesWritten bytes written while expected "
+                    "$expectedTransferLength."));
+                _completer = null;
+              }
+              return;
             }
           }
-        }
-        if (!persistentConnection) {
-          throw new RedirectException(
-              "Non-persistent connections are currently not supported for "
-              "redirects", _connection._redirects);
-        }
-        // Drain body and redirect.
-        inputStream.onData = inputStream.read;
-        if (_statusCode == HttpStatus.SEE_OTHER &&
-            _connection._method == "POST") {
-          _connection.redirect("GET");
-        } else {
-          _connection.redirect();
-        }
-      } else {
-        throw new RedirectLimitExceededException(_connection._redirects);
-      }
-    } else if (statusCode == HttpStatus.UNAUTHORIZED) {
-      _handleUnauthorized();
-    } else if (_connection._onResponse != null) {
-      _connection._onResponse(this);
-    }
+          _controller.add(data);
+        },
+        onError: (error) {
+          _controller.close();
+          if (_completer != null) {
+            _completer.completeError(error);
+            _completer = null;
+          }
+        },
+        onDone: () {
+          _controller.close();
+          if (expectedTransferLength != null) {
+            if (_bytesWritten < expectedTransferLength) {
+              if (_completer != null) {
+                _completer.completeError(new HttpException(
+                    "Content size below specified contentLength. "
+                    " $_bytesWritten bytes written while expected "
+                    "$expectedTransferLength."));
+                _completer = null;
+                return;
+              }
+            }
+          }
+          if (_completer != null) {
+            _completer.complete(this);
+            _completer = null;
+          }
+        },
+        unsubscribeOnError: true);
+    return _controller.stream;
   }
+}
 
-  void _handleUnauthorized() {
+// Extends StreamConsumer as this is an internal type, only used to pipe to.
+class _HttpOutgoing implements StreamConsumer<List<int>, dynamic> {
+  final Completer _dataCompleter = new Completer();
+  final Completer _streamCompleter = new Completer();
+  final _DataValidatorTransformer _validator = new _DataValidatorTransformer();
 
-    void retryRequest(_Credentials cr) {
-      if (cr != null) {
-        // Drain body and retry.
-        // TODO(sgjesse): Support digest.
-        if (cr.scheme == _AuthenticationScheme.BASIC) {
-          inputStream.onData = inputStream.read;
-          _connection._retry();
-          return;
-        }
-      }
+  // Future that completes when all data is written.
+  Future get dataDone => _dataCompleter.future;
 
-      // Fall through to here to perform normal response handling if
-      // there is no sensible authorization handling.
-      if (_connection._onResponse != null) {
-        _connection._onResponse(this);
-      }
-    }
+  // Future that completes with the Stream, once the _HttpClientConnection is
+  // bound to one.
+  Future<Stream<List<int>>> get stream => _streamCompleter.future;
 
-    // Only try to authenticate if there is a challenge in the response.
-    List<String> challenge = _headers[HttpHeaders.WWW_AUTHENTICATE];
-    if (challenge != null && challenge.length == 1) {
-      _HeaderValue header =
-          new _HeaderValue.fromString(challenge[0], parameterSeparator: ",");
-      _AuthenticationScheme scheme =
-          new _AuthenticationScheme.fromString(header.value);
-      String realm = header.parameters["realm"];
-
-      // See if any credentials are available.
-      _Credentials cr =
-          _connection._client._findCredentials(
-              _connection._request._uri, scheme);
-
-      // Ask for more credentials if none found or the one found has
-      // already been used. If it has already been used it must now be
-      // invalid and is removed.
-      if (cr == null || cr.used) {
-        if (cr != null) {
-          _connection._client._removeCredentials(cr);
-        }
-        cr = null;
-        if (_connection._client._authenticate != null) {
-          Future authComplete =
-              _connection._client._authenticate(
-                  _connection._request._uri, scheme.toString(), realm);
-          authComplete.then((credsAvailable) {
-            if (credsAvailable) {
-              cr = _connection._client._findCredentials(
-                  _connection._request._uri, scheme);
-              retryRequest(cr);
-            } else {
-              if (_connection._onResponse != null) {
-                _connection._onResponse(this);
-              }
-            }
-          });
-          return;
-        }
-      } else {
-        // If credentials found prepare for retrying the request.
-        retryRequest(cr);
-        return;
-      }
-    }
+  void setTransferLength(int transferLength) {
+    _validator.expectedTransferLength = transferLength;
+  }
 
-    // Fall through to here to perform normal response handling if
-    // there is no sensible authorization handling.
-    if (_connection._onResponse != null) {
-      _connection._onResponse(this);
-    }
+  Future consume(Stream<List<int>> stream) {
+    stream = stream.transform(_validator);
+    _streamCompleter.complete(stream);
+    _validator.validatorFuture.catchError((e) {
+      _dataCompleter.completeError(e);
+    });
+    return _validator.validatorFuture.then((v) {
+      _dataCompleter.complete();
+      return v;
+    });
   }
+}
 
-  void _onDataReceived(List<int> data) {
-    _buffer.add(data);
-    if (_inputStream != null) _inputStream._dataReceived();
+
+class _HttpClientConnection {
+  final String key;
+  final Socket _socket;
+  final _HttpParser _httpParser;
+  StreamSubscription _subscription;
+  final _HttpClient _httpClient;
+
+  Completer<_HttpIncoming> _nextResponseCompleter;
+  Future _writeDoneFuture;
+
+  _HttpClientConnection(String this.key,
+                        Socket this._socket,
+                        _HttpClient this._httpClient)
+      : _httpParser = new _HttpParser.responseParser() {
+    _socket.pipe(_httpParser);
+    _socket.done.catchError((e) { destroy(); });
+
+    // Set up handlers on the parser here, so we are sure to get 'onDone' from
+    // the parser.
+    _subscription = _httpParser.listen(
+        (incoming) {
+          // Only handle one incoming response at the time. Keep the
+          // stream paused until the response have been processed.
+          _subscription.pause();
+          // We assume the response is not here, until we have send the request.
+          assert(_nextResponseCompleter != null);
+          _nextResponseCompleter.complete(incoming);
+        },
+        onError: (error) {
+          if (_nextResponseCompleter != null) {
+            _nextResponseCompleter.completeError(error);
+          }
+        },
+        onDone: () {
+          close();
+        });
   }
 
-  void _onDataEnd() {
-    if (_inputStream != null) {
-      _inputStream._closeReceived();
-    } else {
-      inputStream._streamMarkedClosed = true;
-    }
+  Future<_HttpIncoming> sendRequest(_HttpOutgoing outgoing) {
+    return outgoing.stream
+      .then((stream) {
+        // Close socket if output data is invalid.
+        outgoing.dataDone.catchError((e) {
+          close();
+        });
+        // Sending request, set up response completer.
+        _nextResponseCompleter = new Completer();
+        _writeDoneFuture = _socket.addStream(stream);
+        // Listen for response.
+        return _nextResponseCompleter.future
+            .whenComplete(() {
+               _nextResponseCompleter = null;
+             })
+            .then((incoming) {
+              incoming.dataDone.then((_) {
+                if (!incoming.headers.persistentConnection) {
+                  close();
+                } else {
+                  // Wait for the socket to be done with writing, before we
+                  // continue.
+                  _writeDoneFuture.then((_) {
+                    _subscription.resume();
+                    // Return connection, now we are done.
+                    _httpClient._returnConnection(this);
+                  });
+                }
+              });
+              // TODO(ajohnsen): Can there be an error on dataDone?
+              return incoming;
+            })
+            // If we see a state error, we failed to get the 'first' element.
+            // Transform the error to a HttpParserException, for consistency.
+            .catchError((error) {
+              throw new HttpParserException(
+                  "Connection closed before data was received");
+            }, test: (error) => error is StateError)
+            .catchError((error) {
+              // We are done with the socket.
+              destroy();
+              throw error;
+            });
+        });
   }
 
-  // Delegate functions for the HttpInputStream implementation.
-  int _streamAvailable() {
-    return _buffer.length;
+  Future<Socket> detachSocket() {
+    return _writeDoneFuture.then((_) =>
+        new _DetachedSocket(_socket, _httpParser.detachIncoming()));
   }
 
-  List<int> _streamRead(int bytesToRead) {
-    return _buffer.readBytes(bytesToRead);
+  void destroy() {
+    _socket.destroy();
+    _httpClient._connectionClosed(this);
   }
 
-  int _streamReadInto(List<int> buffer, int offset, int len) {
-    List<int> data = _buffer.readBytes(len);
-    buffer.setRange(offset, data.length, data);
-    return data.length;
+  void close() {
+    var future = _writeDoneFuture;
+    if (future == null) future = new Future.immediate(null);
+    _httpClient._connectionClosed(this);
+    future.then((_) {
+      _socket.close();
+      // TODO(ajohnsen): Add timeout.
+      // Delay destroy until socket is actually done writing.
+      _socket.done.then((_) => _socket.destroy(),
+                        onError: (_) => _socket.destroy());
+    });
   }
 
-  void _streamSetErrorHandler(callback(e)) {
-    _streamErrorHandler = callback;
-  }
+  HttpConnectionInfo get connectionInfo => _HttpConnectionInfo.create(_socket);
+}
 
-  int _statusCode;
-  String _reasonPhrase;
+class _ConnnectionInfo {
+  _ConnnectionInfo(_HttpClientConnection this.connection, _Proxy this.proxy);
+  final _HttpClientConnection connection;
+  final _Proxy proxy;
+}
 
-  _HttpClientConnection _connection;
-  _HttpInputStream _inputStream;
-  _BufferList _buffer;
 
-  Function _streamErrorHandler;
-}
+class _HttpClient implements HttpClient {
+  // TODO(ajohnsen): Use eviction timeout.
+  static const int DEFAULT_EVICTION_TIMEOUT = 60000;
+  bool _closing = false;
 
+  final Map<String, Queue<_HttpClientConnection>> _idleConnections
+      = new Map<String, Queue<_HttpClientConnection>>();
+  final Set<_HttpClientConnection> _activeConnections
+      = new Set<_HttpClientConnection>();
+  final List<_Credentials> _credentials = [];
+  Function _authenticate;
+  Function _findProxy;
 
-class _HttpClientConnection
-    extends _HttpConnectionBase implements HttpClientConnection {
+  Future<HttpClientRequest> open(String method,
+                                 String host,
+                                 int port,
+                                 String path) {
+    // TODO(sgjesse): The path set here can contain both query and
+    // fragment. They should be cracked and set correctly.
+    return _openUrl(method, new Uri.fromComponents(
+        scheme: "http", domain: host, port: port, path: path));
+  }
 
-  _HttpClientConnection(_HttpClient this._client) {
-    _httpParser = new _HttpParser.responseParser();
+  Future<HttpClientRequest> openUrl(String method, Uri url) {
+    return _openUrl(method, url);
   }
 
-  bool _write(List<int> data, [bool copyBuffer = false]) {
-    return _socket.outputStream.write(data, copyBuffer);
+  Future<HttpClientRequest> get(String host,
+                                int port,
+                                String path) {
+    return open("get", host, port, path);
   }
 
-  bool _writeFrom(List<int> data, [int offset, int len]) {
-    return _socket.outputStream.writeFrom(data, offset, len);
+  Future<HttpClientRequest> getUrl(Uri url) {
+    return _openUrl("get", url);
   }
 
-  bool _flush() {
-    _socket.outputStream.flush();
+  Future<HttpClientRequest> post(String host,
+                                 int port,
+                                 String path) {
+    return open("post", host, port, path);
   }
 
-  bool _close() {
-    _socket.outputStream.close();
+  Future<HttpClientRequest> postUrl(Uri url) {
+    return _openUrl("post", url);
   }
 
-  bool _destroy() {
-    _socket.close();
+  void close({bool force: false}) {
+    _closing = true;
+    // Create flattened copy of _idleConnections, as 'destory' will manipulate
+    // it.
+    var idle = _idleConnections.values.reduce(
+        [],
+        (l, e) {
+          l.addAll(e);
+          return l;
+        });
+    idle.forEach((e) {
+      e.close();
+    });
+    assert(_idleConnections.isEmpty);
+    if (force) {
+      for (var connection in _activeConnections.toList()) {
+        connection.destroy();
+      }
+      assert(_activeConnections.isEmpty);
+      _activeConnections.clear();
+    }
   }
 
-  DetachedSocket _detachSocket() {
-    _socket.onData = null;
-    _socket.onClosed = null;
-    _socket.onError = null;
-    _socket.outputStream.onNoPendingWrites = null;
-    Socket socket = _socket;
-    _socket = null;
-    if (onDetach != null) onDetach();
-    return new _DetachedSocket(socket, _httpParser.readUnparsedData());
+  set authenticate(Future<bool> f(Uri url, String scheme, String realm)) {
+    _authenticate = f;
   }
 
-  void _connectionEstablished(_SocketConnection socketConn) {
-    super._connectionEstablished(socketConn._socket);
-    _socketConn = socketConn;
-    // Register HTTP parser callbacks.
-    _httpParser.responseStart = _onResponseReceived;
-    _httpParser.dataReceived = _onDataReceived;
-    _httpParser.dataEnd = _onDataEnd;
-    _httpParser.error = _onError;
-    _httpParser.closed = _onClosed;
-    _httpParser.requestStart = (method, uri, version) { assert(false); };
-    _state = _HttpConnectionBase.ACTIVE;
+  void addCredentials(Uri url, String realm, HttpClientCredentials cr) {
+    _credentials.add(new _Credentials(url, realm, cr));
   }
 
-  void _checkSocketDone() {
-    if (_isAllDone) {
-      // If we are done writing the response, and either the server
-      // has closed or the connection is not persistent, we must
-      // close.
-      if (_isReadClosed || !_response.persistentConnection) {
-        this.onClosed = () {
-          _client._closedSocketConnection(_socketConn);
-        };
-        _client._closeQueue.add(this);
-      } else if (_socket != null) {
-        _client._returnSocketConnection(_socketConn);
-        _socket = null;
-        _socketConn = null;
-        assert(_pendingRedirect == null || _pendingRetry == null);
-        if (_pendingRedirect != null) {
-          _doRedirect(_pendingRedirect);
-          _pendingRedirect = null;
-        } else if (_pendingRetry != null) {
-          _doRetry(_pendingRetry);
-          _pendingRetry = null;
-        }
+  set findProxy(String f(Uri uri)) => _findProxy = f;
+
+  Future<HttpClientRequest> _openUrl(String method, Uri uri) {
+    if (method == null) {
+      throw new ArgumentError(method);
+    }
+    if (uri.domain.isEmpty || (uri.scheme != "http" && uri.scheme != "https")) {
+      throw new ArgumentError("Unsupported scheme '${uri.scheme}' in $uri");
+    }
+
+    bool isSecure = (uri.scheme == "https");
+    int port = uri.port;
+    if (port == 0) {
+      port = isSecure ?
+          HttpClient.DEFAULT_HTTPS_PORT :
+          HttpClient.DEFAULT_HTTP_PORT;
+    }
+    // Check to see if a proxy server should be used for this connection.
+    var proxyConf = const _ProxyConfiguration.direct();
+    if (_findProxy != null) {
+      // TODO(sgjesse): Keep a map of these as normally only a few
+      // configuration strings will be used.
+      try {
+        proxyConf = new _ProxyConfiguration(_findProxy(uri));
+      } catch (error, stackTrace) {
+        return new Future.immediateError(error, stackTrace);
       }
     }
+    return _getConnection(uri.domain, port, proxyConf, isSecure).then((info) {
+          // Create new internal outgoing connection.
+          var outgoing = new _HttpOutgoing();
+          // Create new request object, wrapping the outgoing connection.
+          var request = new _HttpClientRequest(outgoing,
+                                               uri,
+                                               method.toUpperCase(),
+                                               !info.proxy.isDirect,
+                                               this,
+                                               info.connection);
+          request.headers.host = uri.domain;
+          request.headers.port = port;
+          if (uri.userInfo != null && !uri.userInfo.isEmpty) {
+            // If the URL contains user information use that for basic
+            // authorization
+            String auth =
+                CryptoUtils.bytesToBase64(_encodeString(uri.userInfo));
+            request.headers.set(HttpHeaders.AUTHORIZATION, "Basic $auth");
+          } else {
+            // Look for credentials.
+            _Credentials cr = _findCredentials(uri);
+            if (cr != null) {
+              cr.authorize(request);
+            }
+          }
+          // Start sending the request (lazy, delayed until the user provides
+          // data).
+          info.connection._httpParser.responseToMethod = method;
+          info.connection.sendRequest(outgoing)
+              .then((incoming) {
+                // The full request have been sent and a response is received
+                // containing status-code, headers and etc.
+                request._onIncoming(incoming);
+              })
+              .catchError((error) {
+                // An error occoured before the http-header was parsed. This
+                // could be either a socket-error or parser-error.
+                request._onError(error);
+              });
+          // Return the request to the user. Immediate socket errors are not
+          // handled, thus forwarded to the user.
+          return request;
+        });
   }
 
-  void _requestClosed() {
-    _state |= _HttpConnectionBase.REQUEST_DONE;
-    _checkSocketDone();
+  Future<HttpClientRequest> _openUrlFromRequest(String method,
+                                                Uri uri,
+                                                _HttpClientRequest previous) {
+    return openUrl(method, uri).then((request) {
+          // Only follow redirects if initial request did.
+          request.followRedirects = previous.followRedirects;
+          // Allow same number of redirects.
+          request.maxRedirects = previous.maxRedirects;
+          // Copy headers
+          for (var header in previous.headers._headers.keys) {
+            if (request.headers[header] == null) {
+              request.headers.set(header, previous.headers[header]);
+            }
+          }
+          request.headers.chunkedTransferEncoding = false;
+          request.contentLength = 0;
+          return request;
+        });
   }
 
-  HttpClientRequest open(String method, Uri uri) {
-    _method = method;
-    // Tell the HTTP parser the method it is expecting a response to.
-    _httpParser.responseToMethod = method;
-    // If the connection already have a request this is a retry of a
-    // request. In this case the request object is reused to ensure
-    // that the same headers are send.
-    if (_request != null) {
-      _request._method = method;
-      _request._uri = uri;
-      _request._headers._mutable = true;
-      _request._state = _HttpRequestResponseBase.START;
-    } else {
-      _request = new _HttpClientRequest(method, uri, this);
+  // Return a live connection to the idle pool.
+  void _returnConnection(_HttpClientConnection connection) {
+    _activeConnections.remove(connection);
+    if (_closing) {
+      connection.close();
+      return;
     }
-    _response = new _HttpClientResponse(this);
-    return _request;
-  }
-
-  DetachedSocket detachSocket() {
-    return _detachSocket();
+    // TODO(ajohnsen): Listen for socket close events.
+    if (!_idleConnections.containsKey(connection.key)) {
+      _idleConnections[connection.key] = new Queue();
+    }
+    _idleConnections[connection.key].addLast(connection);
   }
 
-  void _onClosed() {
-    _state |= _HttpConnectionBase.READ_CLOSED;
-    _checkSocketDone();
+  // Remove a closed connnection from the active set.
+  void _connectionClosed(_HttpClientConnection connection) {
+    _activeConnections.remove(connection);
+    if (_idleConnections.containsKey(connection.key)) {
+      _idleConnections[connection.key].remove(connection);
+      if (_idleConnections[connection.key].isEmpty) {
+        _idleConnections.remove(connection.key);
+      }
+    }
   }
 
-  void _onError(e) {
-    // Cancel any pending data in the HTTP parser.
-    _httpParser.cancel();
-    if (_socketConn != null) {
-      _client._closeSocketConnection(_socketConn);
+  // Get a new _HttpClientConnection, either from the idle pool or created from
+  // a new Socket.
+  Future<_ConnnectionInfo> _getConnection(String uriHost,
+                                          int uriPort,
+                                          _ProxyConfiguration proxyConf,
+                                          bool isSecure) {
+    Iterator<_Proxy> proxies = proxyConf.proxies.iterator;
+
+    Future<_ConnnectionInfo> connect(error) {
+      if (!proxies.moveNext()) return new Future.immediateError(error);
+      _Proxy proxy = proxies.current;
+      String host = proxy.isDirect ? uriHost: proxy.host;
+      int port = proxy.isDirect ? uriPort: proxy.port;
+      String key = isSecure ? "ssh:$host:$port" : "$host:$port";
+      if (_idleConnections.containsKey(key)) {
+        var connection = _idleConnections[key].removeFirst();
+        if (_idleConnections[key].isEmpty) {
+          _idleConnections.remove(key);
+        }
+        _activeConnections.add(connection);
+        return new Future.immediate(new _ConnnectionInfo(connection, proxy));
+      }
+      return (isSecure && proxy.isDirect
+                  ? SecureSocket.connect(host,
+                                         port,
+                                         sendClientCertificate: true)
+                  : Socket.connect(host, port))
+        .then((socket) {
+          var connection = new _HttpClientConnection(key, socket, this);
+          _activeConnections.add(connection);
+          return new _ConnnectionInfo(connection, proxy);
+        }, onError: (error) {
+          // Continue with next proxy.
+          return connect(error.error);
+        });
     }
+    return connect(new HttpException("No proxies given"));
+  }
 
-    // If it looks as if we got a bad connection from the connection
-    // pool and the request can be retried do a retry.
-    if (_socketConn != null && _socketConn._fromPool && _request._emptyBody) {
-      String method = _request._method;
-      Uri uri = _request._uri;
-      _socketConn = null;
+  _Credentials _findCredentials(Uri url, [_AuthenticationScheme scheme]) {
+    // Look for credentials.
+    _Credentials cr =
+        _credentials.reduce(null, (_Credentials prev, _Credentials value) {
+          if (value.applies(url, scheme)) {
+            if (prev == null) return value;
+            return value.uri.path.length > prev.uri.path.length ? value : prev;
+          } else {
+            return prev;
+          }
+        });
+    return cr;
+  }
 
-      // Retry the URL using the same connection instance.
-      _httpParser.restart();
-      _client._openUrl(method, uri, this);
-    } else {
-      // Report the error.
-      if (_response != null && _response._streamErrorHandler != null) {
-         _response._streamErrorHandler(e);
-      } else if (_onErrorCallback != null) {
-        _onErrorCallback(e);
-      } else {
-        throw e;
-      }
+  void _removeCredentials(_Credentials cr) {
+    int index = _credentials.indexOf(cr);
+    if (index != -1) {
+      _credentials.removeAt(index);
     }
   }
+}
 
-  void _onResponseReceived(int statusCode,
-                           String reasonPhrase,
-                           String version,
-                           _HttpHeaders headers,
-                           bool hasBody) {
-    _response._onResponseReceived(
-        statusCode, reasonPhrase, version, headers, hasBody);
-  }
 
-  void _onDataReceived(List<int> data) {
-    _response._onDataReceived(data);
+class _HttpConnection {
+  static const _ACTIVE = 0;
+  static const _IDLE = 1;
+  static const _CLOSING = 2;
+  static const _DETACHED = 3;
+
+  int _state = _IDLE;
+
+  final Socket _socket;
+  final _HttpServer _httpServer;
+  final _HttpParser _httpParser;
+  StreamSubscription _subscription;
+
+  Future _writeDoneFuture;
+
+  _HttpConnection(Socket this._socket, _HttpServer this._httpServer)
+      : _httpParser = new _HttpParser.requestParser() {
+    _socket.pipe(_httpParser);
+    _socket.done.catchError((e) => destroy());
+    _subscription = _httpParser.listen(
+        (incoming) {
+          // Only handle one incoming request at the time. Keep the
+          // stream paused until the request has been send.
+          _subscription.pause();
+          _state = _ACTIVE;
+          var outgoing = new _HttpOutgoing();
+          _writeDoneFuture = outgoing.stream.then(_socket.addStream);
+          var response = new _HttpResponse(
+              incoming.headers.protocolVersion,
+              outgoing);
+          var request = new _HttpRequest(response, incoming, _httpServer, this);
+          response._ignoreBody = request.method == "HEAD";
+          response._httpRequest = request;
+          outgoing.dataDone.then((_) {
+            if (_state == _DETACHED) return;
+            if (response.headers.persistentConnection &&
+                incoming.fullBodyRead) {
+              // Wait for the socket to be done with writing, before we
+              // continue.
+              _writeDoneFuture.then((_) {
+                _state = _IDLE;
+                // Resume the subscription for incoming requests as the
+                // request is now processed.
+                _subscription.resume();
+              });
+            } else {
+              // Close socket, keep-alive not used or body sent before received
+              // data was handled.
+              close();
+            }
+          }).catchError((e) {
+            close();
+          });
+          _httpServer._handleRequest(request);
+        },
+        onDone: () {
+          close();
+        },
+        onError: (error) {
+          _httpServer._handleError(error);
+          destroy();
+        });
   }
 
-  void _onDataEnd(bool close) {
-    _state |= _HttpConnectionBase.RESPONSE_DONE;
-    _response._onDataEnd();
-    _checkSocketDone();
+  void destroy() {
+    if (_state == _CLOSING || _state == _DETACHED) return;
+    _state = _CLOSING;
+    _socket.destroy();
+    _httpServer._connectionClosed(this);
   }
 
-  void _onClientShutdown() {
-    if (!_isResponseDone) {
-      _onError(new HttpException("Client shutdown"));
-    }
+  void close() {
+    if (_state == _CLOSING || _state == _DETACHED) return;
+    _state = _CLOSING;
+    var future = _writeDoneFuture;
+    if (future == null) future = new Future.immediate(null);
+    _httpServer._connectionClosed(this);
+    future.then((_) {
+      _socket.close();
+      // TODO(ajohnsen): Add timeout.
+      // Delay destroy until socket is actually done writing.
+      _socket.done.then((_) => _socket.destroy(),
+                        onError: (_) => _socket.destroy());
+    });
   }
 
-  void set onRequest(void handler(HttpClientRequest request)) {
-    _onRequest = handler;
+  Future<Socket> detachSocket() {
+    _state = _DETACHED;
+    // Remove connection from server.
+    _httpServer._connectionClosed(this);
+
+    _HttpDetachedIncoming detachedIncoming = _httpParser.detachIncoming();
+
+    return _writeDoneFuture.then((_) {
+      return new _DetachedSocket(_socket, detachedIncoming);
+    });
   }
 
-  void set onResponse(void handler(HttpClientResponse response)) {
-    _onResponse = handler;
+  HttpConnectionInfo get connectionInfo => _HttpConnectionInfo.create(_socket);
+
+  bool get _isActive => _state == _ACTIVE;
+  bool get _isIdle => _state == _IDLE;
+  bool get _isClosing => _state == _CLOSING;
+  bool get _isDetached => _state == _DETACHED;
+}
+
+
+// HTTP server waiting for socket connections.
+class _HttpServer extends Stream<HttpRequest> implements HttpServer {
+
+  static Future<HttpServer> bind(String host, int port, int backlog) {
+    return ServerSocket.bind(host, port, backlog).then((socket) {
+      return new _HttpServer._(socket, true);
+    });
   }
 
-  void set onError(void callback(e)) {
-    _onErrorCallback = callback;
+  static Future<HttpServer> bindSecure(String host,
+                                       int port,
+                                       int backlog,
+                                       String certificate_name,
+                                       bool requestClientCertificate) {
+    return SecureServerSocket.bind(
+        host,
+        port,
+        backlog,
+        certificate_name,
+        requestClientCertificate: requestClientCertificate)
+        .then((socket) {
+          return new _HttpServer._(socket, true);
+        });
   }
 
-  void _doRetry(_RedirectInfo retry) {
-    assert(_socketConn == null);
+  _HttpServer._(this._serverSocket, this._closeServer);
 
-    // Retry the URL using the same connection instance.
-    _state = _HttpConnectionBase.IDLE;
-    _client._openUrl(retry.method, retry.location, this);
+  _HttpServer.listenOn(ServerSocket this._serverSocket)
+      : _closeServer = false;
+
+  StreamSubscription<HttpRequest> listen(void onData(HttpRequest event),
+                                         {void onError(AsyncError error),
+                                         void onDone(),
+                                         bool unsubscribeOnError}) {
+    _serverSocket.listen(
+        (Socket socket) {
+          // Accept the client connection.
+          _HttpConnection connection = new _HttpConnection(socket, this);
+          _connections.add(connection);
+        },
+        onError: _controller.signalError,
+        onDone: _controller.close);
+    return _controller.stream.listen(onData,
+                                     onError: onError,
+                                     onDone: onDone,
+                                     unsubscribeOnError: unsubscribeOnError);
   }
 
-  void _retry() {
-    var retry = new _RedirectInfo(_response.statusCode, _method, _request._uri);
-    // The actual retry is postponed until both response and request
-    // are done.
-    if (_isAllDone) {
-      _doRetry(retry);
-    } else {
-      // Prepare for retry.
-      assert(_pendingRedirect == null);
-      _pendingRetry = retry;
+  void close() {
+    closed = true;
+    if (_serverSocket != null && _closeServer) {
+      _serverSocket.close();
+    }
+    if (_sessionManagerInstance != null) {
+      _sessionManagerInstance.close();
+      _sessionManagerInstance = null;
+    }
+    for (_HttpConnection connection in _connections.toList()) {
+      connection.destroy();
     }
+    _connections.clear();
   }
 
-  void _doRedirect(_RedirectInfo redirect) {
-    assert(_socketConn == null);
-
-    if (_redirects == null) {
-      _redirects = new List<_RedirectInfo>();
-    }
-    _redirects.add(redirect);
-    _doRetry(redirect);
+  int get port {
+    if (closed) throw new HttpException("HttpServer is not bound to a socket");
+    return _serverSocket.port;
   }
 
-  void redirect([String method, Uri url]) {
-    if (method == null) method = _method;
-    if (url == null) {
-      url = Uri.parse(_response.headers.value(HttpHeaders.LOCATION));
-    }
-    // Always set the content length to 0 for redirects.
-    var mutable = _request._headers._mutable;
-    _request._headers._mutable = true;
-    _request._headers.contentLength = 0;
-    _request._headers._mutable = mutable;
-    _request._bodyBytesWritten = 0;
-    var redirect = new _RedirectInfo(_response.statusCode, method, url);
-    // The actual redirect is postponed until both response and
-    // request are done.
-    assert(_pendingRetry == null);
-    _pendingRedirect = redirect;
-  }
-
-  List<RedirectInfo> get redirects => _redirects;
-
-  Function _onRequest;
-  Function _onResponse;
-  Function _onErrorCallback;
-
-  _HttpClient _client;
-  _SocketConnection _socketConn;
-  HttpClientRequest _request;
-  HttpClientResponse _response;
-  String _method;
-  bool _usingProxy;
-
-  // Redirect handling
-  bool followRedirects = true;
-  int maxRedirects = 5;
-  List<_RedirectInfo> _redirects;
-  _RedirectInfo _pendingRedirect;
-  _RedirectInfo _pendingRetry;
-
-  // Callbacks.
-  var requestReceived;
-}
+  set sessionTimeout(int timeout) {
+    _sessionManager.sessionTimeout = timeout;
+  }
 
+  void _handleRequest(HttpRequest request) {
+    _controller.add(request);
+  }
 
-// Class for holding keep-alive sockets in the cache for the HTTP
-// client together with the connection information.
-class _SocketConnection {
-  _SocketConnection(String this._host,
-                    int this._port,
-                    Socket this._socket);
+  void _handleError(AsyncError error) {
+    if (!closed) _controller.signalError(error);
+  }
 
-  void _markReturned() {
-    // Any activity on the socket while waiting in the pool will
-    // invalidate the connection os that it is not reused.
-    _socket.onData = _invalidate;
-    _socket.onClosed = _invalidate;
-    _socket.onError = (_) => _invalidate();
-    _returnTime = new DateTime.now();
-    _httpClientConnection = null;
+  void _connectionClosed(_HttpConnection connection) {
+    _connections.remove(connection);
   }
 
-  void _markRetrieved() {
-    _socket.onData = null;
-    _socket.onClosed = null;
-    _socket.onError = null;
-    _httpClientConnection = null;
+  _HttpSessionManager get _sessionManager {
+    // Lazy init.
+    if (_sessionManagerInstance == null) {
+      _sessionManagerInstance = new _HttpSessionManager();
+    }
+    return _sessionManagerInstance;
   }
 
-  void _close() {
-    _socket.onData = null;
-    _socket.onClosed = null;
-    _socket.onError = null;
-    _httpClientConnection = null;
-    _socket.close();
+  HttpConnectionsInfo connectionsInfo() {
+    HttpConnectionsInfo result = new HttpConnectionsInfo();
+    result.total = _connections.length;
+    _connections.forEach((_HttpConnection conn) {
+      if (conn._isActive) {
+        result.active++;
+      } else if (conn._isIdle) {
+        result.idle++;
+      } else {
+        assert(conn._isClosing);
+        result.closing++;
+      }
+    });
+    return result;
   }
 
-  Duration _idleTime(DateTime now) => now.difference(_returnTime);
+  _HttpSessionManager _sessionManagerInstance;
 
-  bool get _fromPool => _returnTime != null;
+  // Indicated if the http server has been closed.
+  bool closed = false;
 
-  void _invalidate() {
-    _valid = false;
-    _close();
-  }
+  // The server listen socket.
+  final ServerSocket _serverSocket;
+  final bool _closeServer;
 
-  int get hashCode => _socket.hashCode;
+  // Set of currently connected clients.
+  final Set<_HttpConnection> _connections = new Set<_HttpConnection>();
+  final StreamController<HttpRequest> _controller
+      = new StreamController<HttpRequest>();
 
-  String _host;
-  int _port;
-  Socket _socket;
-  DateTime _returnTime;
-  bool _valid = true;
-  HttpClientConnection _httpClientConnection;
+  // TODO(ajohnsen): Use close queue?
 }
 
+
 class _ProxyConfiguration {
   static const String PROXY_PREFIX = "PROXY ";
   static const String DIRECT_PREFIX = "DIRECT";
@@ -1844,6 +1485,7 @@ class _ProxyConfiguration {
   final List<_Proxy> proxies;
 }
 
+
 class _Proxy {
   const _Proxy(this.host, this.port) : isDirect = false;
   const _Proxy.direct() : host = null, port = null, isDirect = true;
@@ -1853,376 +1495,59 @@ class _Proxy {
   final bool isDirect;
 }
 
-class _HttpClient implements HttpClient {
-  static const int DEFAULT_EVICTION_TIMEOUT = 60000;
-
-  _HttpClient() : _openSockets = new Map(),
-                  _activeSockets = new Set(),
-                  _closeQueue = new _CloseQueue(),
-                  credentials = new List<_Credentials>(),
-                  _shutdown = false;
-
-  HttpClientConnection open(
-      String method, String host, int port, String path) {
-    // TODO(sgjesse): The path set here can contain both query and
-    // fragment. They should be cracked and set correctly.
-    return _open(method, new Uri.fromComponents(
-        scheme: "http", domain: host, port: port, path: path));
-  }
-
-  HttpClientConnection _open(String method,
-                             Uri uri,
-                             [_HttpClientConnection connection]) {
-    if (_shutdown) throw new HttpException("HttpClient shutdown");
-    if (method == null || uri.domain.isEmpty) {
-      throw new ArgumentError(null);
-    }
-    return _prepareHttpClientConnection(method, uri, connection);
-  }
-
-  HttpClientConnection openUrl(String method, Uri url) {
-    return _openUrl(method, url);
-  }
-
-  HttpClientConnection _openUrl(String method,
-                                Uri url,
-                                [_HttpClientConnection connection]) {
-    if (url.scheme != "http" && url.scheme != "https") {
-      throw new HttpException("Unsupported URL scheme ${url.scheme}");
-    }
-    return _open(method, url, connection);
-  }
-
-  HttpClientConnection get(String host, int port, String path) {
-    return open("GET", host, port, path);
-  }
-
-  HttpClientConnection getUrl(Uri url) => _openUrl("GET", url);
-
-  HttpClientConnection post(String host, int port, String path) {
-    return open("POST", host, port, path);
-  }
-
-  HttpClientConnection postUrl(Uri url) => _openUrl("POST", url);
-
-  set authenticate(Future<bool> f(Uri url, String scheme, String realm)) {
-    _authenticate = f;
-  }
-
-  void addCredentials(
-      Uri url, String realm, HttpClientCredentials cr) {
-    credentials.add(new _Credentials(url, realm, cr));
-  }
-
-  set sendClientCertificate(bool send) => _sendClientCertificate = send;
-
-  set clientCertificate(String nickname) => _clientCertificate = nickname;
-
-  set findProxy(String f(Uri uri)) => _findProxy = f;
-
-  void shutdown({bool force: false}) {
-    if (force) _closeQueue.shutdown();
-    new Map.from(_openSockets).forEach(
-        (String key, Queue<_SocketConnection> connections) {
-      while (!connections.isEmpty) {
-        _SocketConnection socketConn = connections.removeFirst();
-        socketConn._socket.close();
-      }
-    });
-    if (force) {
-      _activeSockets.toList().forEach((_SocketConnection socketConn) {
-        socketConn._httpClientConnection._onClientShutdown();
-        socketConn._close();
-      });
-    }
-    if (_evictionTimer != null) _cancelEvictionTimer();
-    _shutdown = true;
-  }
-
-  void _cancelEvictionTimer() {
-    _evictionTimer.cancel();
-    _evictionTimer = null;
-  }
-
-  String _connectionKey(String host, int port) {
-    return "$host:$port";
-  }
-
-  HttpClientConnection _prepareHttpClientConnection(
-      String method,
-      Uri url,
-      [_HttpClientConnection connection]) {
-
-    void _establishConnection(String host,
-                              int port,
-                              _ProxyConfiguration proxyConfiguration,
-                              int proxyIndex,
-                              bool reusedConnection,
-                              bool secure) {
-
-      void _connectionOpened(_SocketConnection socketConn,
-                             _HttpClientConnection connection,
-                             bool usingProxy) {
-        socketConn._httpClientConnection = connection;
-        connection._usingProxy = usingProxy;
-        connection._connectionEstablished(socketConn);
-        HttpClientRequest request = connection.open(method, url);
-        request.headers.host = host;
-        request.headers.port = port;
-        if (url.userInfo != null && !url.userInfo.isEmpty) {
-          // If the URL contains user information use that for basic
-          // authorization
-          _UTF8Encoder encoder = new _UTF8Encoder();
-          String auth =
-              CryptoUtils.bytesToBase64(encoder.encodeString(url.userInfo));
-          request.headers.set(HttpHeaders.AUTHORIZATION, "Basic $auth");
-        } else {
-          // Look for credentials.
-          _Credentials cr = _findCredentials(url);
-          if (cr != null) {
-            cr.authorize(request);
-          }
-        }
-        // A reused connection is indicating either redirect or retry
-        // where the onRequest callback should not be issued again.
-        if (connection._onRequest != null && !reusedConnection) {
-          connection._onRequest(request);
-        } else {
-          request.outputStream.close();
-        }
-      }
-
-      assert(proxyIndex < proxyConfiguration.proxies.length);
-
-      // Determine the actual host to connect to.
-      String connectHost;
-      int connectPort;
-      _Proxy proxy = proxyConfiguration.proxies[proxyIndex];
-      if (proxy.isDirect) {
-        connectHost = host;
-        connectPort = port;
-      } else {
-        connectHost = proxy.host;
-        connectPort = proxy.port;
-      }
-
-      // If there are active connections for this key get the first one
-      // otherwise create a new one.
-      String key = _connectionKey(connectHost, connectPort);
-      Queue socketConnections = _openSockets[key];
-      // Remove active connections that are not valid any more or of
-      // the wrong type (HTTP or HTTPS).
-      if (socketConnections != null) {
-        while (!socketConnections.isEmpty) {
-          if (socketConnections.first._valid) {
-            // If socket has the same properties, exit loop with found socket.
-            var socket = socketConnections.first._socket;
-            if (!secure && socket is! SecureSocket) break;
-            if (secure && socket is SecureSocket &&
-                 _sendClientCertificate == socket.sendClientCertificate &&
-                 _clientCertificate == socket.certificateName) break;
-          }
-          socketConnections.removeFirst()._close();
-        }
-      }
-      if (socketConnections == null || socketConnections.isEmpty) {
-        Socket socket = secure && proxy.isDirect ?
-            new SecureSocket(connectHost,
-                             connectPort,
-                             sendClientCertificate: _sendClientCertificate,
-                             certificateName: _clientCertificate) :
-            new Socket(connectHost, connectPort);
-        // Until the connection is established handle connection errors
-        // here as the HttpClientConnection object is not yet associated
-        // with the socket.
-        socket.onError = (e) {
-          proxyIndex++;
-          if (proxyIndex < proxyConfiguration.proxies.length) {
-            // Try the next proxy in the list.
-            _establishConnection(
-                host, port, proxyConfiguration, proxyIndex, false, secure);
-          } else {
-            // Report the error through the HttpClientConnection object to
-            // the client.
-            connection._onError(e);
-          }
-        };
-        socket.onConnect = () {
-          // When the connection is established, clear the error
-          // callback as it will now be handled by the
-          // HttpClientConnection object which will be associated with
-          // the connected socket.
-          socket.onError = null;
-          _SocketConnection socketConn =
-              new _SocketConnection(connectHost, connectPort, socket);
-          _activeSockets.add(socketConn);
-          _connectionOpened(socketConn, connection, !proxy.isDirect);
-        };
-      } else {
-        _SocketConnection socketConn = socketConnections.removeFirst();
-        socketConn._markRetrieved();
-        _activeSockets.add(socketConn);
-        Timer.run(() =>
-                  _connectionOpened(socketConn, connection, !proxy.isDirect));
-
-        // Get rid of eviction timer if there are no more active connections.
-        if (socketConnections.isEmpty) _openSockets.remove(key);
-        if (_openSockets.isEmpty) _cancelEvictionTimer();
-      }
-    }
-
-    // Find out if we want a secure socket.
-    bool is_secure = (url.scheme == "https");
-
-    // Find the TCP host and port.
-    String host = url.domain;
-    int port = url.port;
-    if (port == 0) {
-      port = is_secure ?
-          HttpClient.DEFAULT_HTTPS_PORT :
-          HttpClient.DEFAULT_HTTP_PORT;
-    }
-    // Create a new connection object if we are not re-using an existing one.
-    var reusedConnection = false;
-    if (connection == null) {
-      connection = new _HttpClientConnection(this);
-    } else {
-      reusedConnection = true;
-    }
-    connection.onDetach = () => _activeSockets.remove(connection._socketConn);
-
-    // Check to see if a proxy server should be used for this connection.
-    _ProxyConfiguration proxyConfiguration = const _ProxyConfiguration.direct();
-    if (_findProxy != null) {
-      // TODO(sgjesse): Keep a map of these as normally only a few
-      // configuration strings will be used.
-      proxyConfiguration = new _ProxyConfiguration(_findProxy(url));
-    }
-
-    // Establish the connection starting with the first proxy configured.
-    _establishConnection(host,
-                         port,
-                         proxyConfiguration,
-                         0,
-                         reusedConnection,
-                         is_secure);
 
-    return connection;
+class _HttpConnectionInfo implements HttpConnectionInfo {
+  static _HttpConnectionInfo create(Socket socket) {
+    if (socket == null) return null;
+    try {
+      _HttpConnectionInfo info = new _HttpConnectionInfo._();
+      info.remoteHost = socket.remoteHost;
+      info.remotePort = socket.remotePort;
+      info.localPort = socket.port;
+      return info;
+    } catch (e) { }
+    return null;
   }
 
-  void _returnSocketConnection(_SocketConnection socketConn) {
-    // If the HTTP client is being shutdown don't return the connection.
-    if (_shutdown) {
-      socketConn._close();
-      return;
-    };
-
-    // Mark socket as returned to unregister from the old connection.
-    socketConn._markReturned();
-
-    String key = _connectionKey(socketConn._host, socketConn._port);
+  _HttpConnectionInfo._();
 
-    // Get or create the connection list for this key.
-    Queue sockets = _openSockets[key];
-    if (sockets == null) {
-      sockets = new Queue();
-      _openSockets[key] = sockets;
-    }
-
-    // If there is currently no eviction timer start one.
-    if (_evictionTimer == null) {
-      void _handleEviction(Timer timer) {
-        DateTime now = new DateTime.now();
-        List<String> emptyKeys = new List<String>();
-        _openSockets.forEach(
-            (String key, Queue<_SocketConnection> connections) {
-              // As returned connections are added at the head of the
-              // list remove from the tail.
-              while (!connections.isEmpty) {
-                _SocketConnection socketConn = connections.last;
-                if (socketConn._idleTime(now).inMilliseconds >
-                    DEFAULT_EVICTION_TIMEOUT) {
-                  connections.removeLast();
-                  socketConn._socket.close();
-                  if (connections.isEmpty) emptyKeys.add(key);
-                } else {
-                  break;
-                }
-              }
-            });
+  String remoteHost;
+  int remotePort;
+  int localPort;
+}
 
-        // Remove the keys for which here are no more open connections.
-        emptyKeys.forEach((String key) => _openSockets.remove(key));
 
-        // If all connections where evicted cancel the eviction timer.
-        if (_openSockets.isEmpty) _cancelEvictionTimer();
-      }
-      _evictionTimer = new Timer.repeating(const Duration(seconds: 10),
-                                           _handleEviction);
-    }
+class _DetachedSocket implements Socket {
+  final Stream<List<int>> _incoming;
+  final Socket _socket;
 
-    // Return connection.
-    _activeSockets.remove(socketConn);
-    sockets.addFirst(socketConn);
-  }
+  _DetachedSocket(this._socket, this._incoming);
 
-  void _closeSocketConnection(_SocketConnection socketConn) {
-    socketConn._close();
-    _activeSockets.remove(socketConn);
+  StreamSubscription<List<int>> listen(void onData(List<int> event),
+                                       {void onError(AsyncError error),
+                                        void onDone(),
+                                        bool unsubscribeOnError}) {
+    return _incoming.listen(onData,
+                            onError: onError,
+                            onDone: onDone,
+                            unsubscribeOnError: unsubscribeOnError);
   }
 
-  void _closedSocketConnection(_SocketConnection socketConn) {
-    _activeSockets.remove(socketConn);
+  Future<Socket> consume(Stream<List<int>> stream) {
+    return _socket.consume(stream);
   }
 
-  _Credentials _findCredentials(Uri url, [_AuthenticationScheme scheme]) {
-    // Look for credentials.
-    _Credentials cr =
-        credentials.reduce(null, (_Credentials prev, _Credentials value) {
-          if (value.applies(url, scheme)) {
-            if (prev == null) return value;
-            return value.uri.path.length > prev.uri.path.length ? value : prev;
-          } else {
-            return prev;
-          }
-        });
-    return cr;
+  Future<Socket> addStream(Stream<List<int>> stream) {
+    return _socket.addStream(stream);
   }
 
-  void _removeCredentials(_Credentials cr) {
-    int index = credentials.indexOf(cr);
-    if (index != -1) {
-      credentials.removeAt(index);
-    }
+  void addString(String string, [Encoding encoding = Encoding.UTF_8]) {
+    return _socket.addString(string, encoding);
   }
 
-  Function _onOpen;
-  Map<String, Queue<_SocketConnection>> _openSockets;
-  Set<_SocketConnection> _activeSockets;
-  _CloseQueue _closeQueue;
-  List<_Credentials> credentials;
-  Timer _evictionTimer;
-  Function _findProxy;
-  Function _authenticate;
-  bool _sendClientCertificate = false;
-  String _clientCertificate;
-  bool _shutdown;  // Has this HTTP client been shutdown?
-}
-
-
-class _HttpConnectionInfo implements HttpConnectionInfo {
-  String remoteHost;
-  int remotePort;
-  int localPort;
-}
-
-
-class _DetachedSocket implements DetachedSocket {
-  _DetachedSocket(this._socket, this._unparsedData);
-  Socket get socket => _socket;
-  List<int> get unparsedData => _unparsedData;
-  Socket _socket;
-  List<int> _unparsedData;
+  void destroy() => _socket.destroy();
+  void add(List<int> data) => _socket.add(data);
+  Future<Socket> close() => _socket.close();
 }
 
 
@@ -2300,10 +1625,8 @@ class _HttpClientBasicCredentials implements HttpClientBasicCredentials {
     // Proxy-Authenticate headers, see
     // http://tools.ietf.org/html/draft-reschke-basicauth-enc-06. For
     // now always use UTF-8 encoding.
-    _UTF8Encoder encoder = new _UTF8Encoder();
     String auth =
-        CryptoUtils.bytesToBase64(encoder.encodeString(
-            "$username:$password"));
+        CryptoUtils.bytesToBase64(_encodeString("$username:$password"));
     request.headers.set(HttpHeaders.AUTHORIZATION, "Basic $auth");
   }
 
@@ -2328,7 +1651,6 @@ class _HttpClientDigestCredentials implements HttpClientDigestCredentials {
 }
 
 
-
 class _RedirectInfo implements RedirectInfo {
   const _RedirectInfo(int this.statusCode,
                       String this.method,