nweiz@google.com
7774c6f38a
R=kevmoo@google.com Review URL: https://codereview.chromium.org//297593003 git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@36394 260f80e4-7a28-3924-810f-c04153c831b5
62 lines
2.7 KiB
Dart
62 lines
2.7 KiB
Dart
// Copyright (c) 2014, the Dart project authors. Please see the AUTHORS file
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// for details. All rights reserved. Use of this source code is governed by a
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// BSD-style license that can be found in the LICENSE file.
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library shelf_web_socket;
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import 'package:shelf/shelf.dart';
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import 'src/web_socket_handler.dart';
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/// A typedef used to determine if a function takes two arguments or not.
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typedef _BinaryFunction(arg1, arg2);
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/// Creates a Shelf handler that upgrades HTTP requests to WebSocket
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/// connections.
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///
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/// Only valid WebSocket upgrade requests are upgraded. If a request doesn't
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/// look like a WebSocket upgrade request, a 404 Not Found is returned; if a
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/// request looks like an upgrade request but is invalid, a 400 Bad Request is
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/// returned; and if a request is a valid upgrade request but has an origin that
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/// doesn't match [allowedOrigins] (see below), a 403 Forbidden is returned.
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/// This means that this can be placed first in a [Cascade] and only upgrade
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/// requests will be handled.
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///
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/// The [onConnection] must take a [CompatibleWebSocket] as its first argument.
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/// It may also take a string, the [WebSocket subprotocol][], as its second
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/// argument. The subprotocol is determined by looking at the client's
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/// `Sec-WebSocket-Protocol` header and selecting the first entry that also
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/// appears in [protocols]. If no subprotocols are shared between the client and
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/// the server, `null` will be passed instead. Note that if [onConnection] takes
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/// two arguments, [protocols] must be passed.
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///
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/// [WebSocket subprotocol]: https://tools.ietf.org/html/rfc6455#section-1.9
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///
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/// If [allowedOrigins] is passed, browser connections will only be accepted if
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/// they're made by a script from one of the given origins. This ensures that
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/// malicious scripts running in the browser are unable to fake a WebSocket
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/// handshake. Note that non-browser programs can still make connections freely.
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/// See also the WebSocket spec's discussion of [origin considerations][].
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///
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/// [origin considerations]: https://tools.ietf.org/html/rfc6455#section-10.2
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Handler webSocketHandler(Function onConnection, {Iterable<String> protocols,
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Iterable<String> allowedOrigins}) {
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if (protocols != null) protocols = protocols.toSet();
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if (allowedOrigins != null) {
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allowedOrigins = allowedOrigins
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.map((origin) => origin.toLowerCase()).toSet();
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}
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if (onConnection is! _BinaryFunction) {
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if (protocols != null) {
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throw new ArgumentError("If protocols is non-null, onConnection must "
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"take two arguments, the WebSocket and the protocol.");
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}
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var innerOnConnection = onConnection;
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onConnection = (webSocket, _) => innerOnConnection(webSocket);
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}
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return new WebSocketHandler(onConnection, protocols, allowedOrigins).handle;
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}
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