Add new VirtualHost class to http_server package, for handling multiple hosts on multiple sources (…

pkg/http_server/lib/src/virtual_host.dart

+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+part of http_server;
+
+
+/**
+ * The [VirtualHost] class is a utility class for handling multiple hosts on
+ * multiple sources, by using a named-based approach.
+ */
+abstract class VirtualHost {
+  /**
+   * Get the [Stream] of [HttpRequest]s, not matching any hosts. If unused, the
+   * default implementation will result in a [HttpHeaders.FORBIDDEN] response.
+   */
+  Stream<HttpRequest> get unhandled;
+
+  /**
+   * Construct a new [VirtualHost].
+   *
+   * The optional [source] is a shortcut for calling [addSource].
+   *
+   * Example of usage:
+   *
+   *   HttpServer.bind(..., 80).then((server) {
+   *     var virtualHost = new VirtualHost(server);
+   *     virtualServer.addHost('static.myserver.com')
+   *         .listen(...);
+   *     virtualServer.addHost('cache.myserver.com')
+   *         .listen(...);
+   *   })
+   */
+  factory VirtualHost([Stream<HttpRequest> source]) => new _VirtualHost(source);
+
+  /**
+   * Provide another source of [HttpRequest]s in the form of a [Stream].
+   */
+  void addSource(Stream<HttpRequest> source);
+
+
+  /**
+   * Add a host to the [VirtualHost] instance. The host can be either a specific
+   * domain (`my.domain.name`) or a wildcard-based domain name
+   * (`*.domain.name`). The former will only match the specific domain name
+   * while the latter will match any series of sub-domains.
+   *
+   * If both `my.domain.name` and `*.domain.name` is specified, the most
+   * qualified will take precedence, `my.domain.name` in this case.
+   */
+  Stream<HttpRequest> addHost(String host);
+}
+
+
+class _VirtualHostDomain {
+  StreamController<HttpRequest> any;
+  StreamController<HttpRequest> exact;
+  Map<String, _VirtualHostDomain> subDomains = {};
+}
+
+
+class _VirtualHost implements VirtualHost {
+  final _VirtualHostDomain _topDomain = new _VirtualHostDomain();
+  StreamController<HttpRequest> _unhandledController;
+
+  Stream<HttpRequest> get unhandled {
+    if (_unhandledController == null) {
+      _unhandledController = new StreamController<HttpRequest>();
+    }
+    return _unhandledController.stream;
+  }
+
+  _VirtualHost([Stream<HttpRequest> source]) {
+    if (source != null) addSource(source);
+  }
+
+  void addSource(Stream<HttpRequest> source) {
+    source.listen((request) {
+      var host = request.headers.host;
+      if (host == null) {
+        _unhandled(request);
+        return;
+      }
+      var domains = host.split('.');
+      var current = _topDomain;
+      var any;
+      for (var i = domains.length - 1; i >= 0; i--) {
+        if (current.any != null) any = current.any;
+        if (i == 0) {
+          var last = current.subDomains[domains[i]];
+          if (last != null && last.exact != null) {
+            last.exact.add(request);
+            return;
+          }
+        } else {
+          if (!current.subDomains.containsKey(domains[i])) {
+            break;
+          }
+          current = current.subDomains[domains[i]];
+        }
+      }
+      if (any != null) {
+        any.add(request);
+        return;
+      }
+      _unhandled(request);
+    });
+  }
+
+  Stream<HttpRequest> addHost(String host) {
+    if (host.lastIndexOf('*') > 0) {
+      throw new ArgumentError(
+          'Wildcards are only allowed in the beginning of a host');
+    }
+    var controller = new StreamController<HttpRequest>();
+    var domains = host.split('.');
+    var current = _topDomain;
+    for (var i = domains.length - 1; i >= 0; i--) {
+      if (domains[i] == '*') {
+        if (current.any != null) {
+          throw new ArgumentError('Host is already provided');
+        }
+        current.any = controller;
+      } else {
+        if (!current.subDomains.containsKey(domains[i])) {
+          current.subDomains[domains[i]] = new _VirtualHostDomain();
+        }
+        if (i > 0) {
+          current = current.subDomains[domains[i]];
+        } else {
+          if (current.subDomains[domains[i]].exact != null) {
+            throw new ArgumentError('Host is already provided');
+          }
+          current.subDomains[domains[i]].exact = controller;
+        }
+      }
+    }
+    return controller.stream;
+  }
+
+  void _unhandled(HttpRequest request) {
+    if (_unhandledController != null) {
+      _unhandledController.add(request);
+      return;
+    }
+    request.response.statusCode = HttpStatus.FORBIDDEN;
+    request.response.close();
+  }
+}