Add Pale Moon

application/palemoon/components/feeds/WebContentConverter.js

@@ -0,0 +1,932 @@
+/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+Components.utils.import("resource://gre/modules/XPCOMUtils.jsm");
+Components.utils.import("resource://gre/modules/PrivateBrowsingUtils.jsm");
+
+const Cc = Components.classes;
+const Ci = Components.interfaces;
+const Cr = Components.results;
+
+function LOG(str) {
+  dump("*** " + str + "\n");
+}
+
+const WCCR_CONTRACTID = "@mozilla.org/embeddor.implemented/web-content-handler-registrar;1";
+const WCCR_CLASSID = Components.ID("{792a7e82-06a0-437c-af63-b2d12e808acc}");
+
+const WCC_CLASSID = Components.ID("{db7ebf28-cc40-415f-8a51-1b111851df1e}");
+const WCC_CLASSNAME = "Web Service Handler";
+
+const TYPE_MAYBE_FEED = "application/vnd.mozilla.maybe.feed";
+const TYPE_ANY = "*/*";
+const TYPE_BLACKLIST = [
+        "application/x-www-form-urlencoded",
+        "application/xhtml+xml",
+        "application/xml",
+        "application/mathml+xml",
+        "application/xslt+xml",
+        "application/x-xpinstall",
+        "image/gif",
+        "image/jpg",
+        "image/jpeg",
+        "image/png",
+        "image/x-png",
+        "image/webp",
+#ifdef MOZ_JXR
+        "image/jxr",
+        "image/vnd.ms-photo",
+#endif
+        "image/svg+xml",
+        "image/bmp",
+        "image/x-ms-bmp",
+        "image/icon",
+        "image/x-icon",
+        "image/vnd.microsoft.icon",
+        "multipart/x-mixed-replace",
+        "multipart/form-data",
+        "text/cache-manifest",
+        "text/css",
+        "text/xsl",
+        "text/html",
+        "text/ping",
+        "text/plain",
+        "text/xml",
+        "text/javascript",  // To prevent malicious intent blocking scripting.
+        "text/ecmascript"];
+
+const PREF_CONTENTHANDLERS_AUTO = "browser.contentHandlers.auto.";
+const PREF_CONTENTHANDLERS_BRANCH = "browser.contentHandlers.types.";
+const PREF_SELECTED_WEB = "browser.feeds.handlers.webservice";
+const PREF_SELECTED_ACTION = "browser.feeds.handler";
+const PREF_SELECTED_READER = "browser.feeds.handler.default";
+const PREF_HANDLER_EXTERNAL_PREFIX = "network.protocol-handler.external";
+const PREF_ALLOW_DIFFERENT_HOST = "goanna.handlerService.allowRegisterFromDifferentHost";
+
+const STRING_BUNDLE_URI = "chrome://browser/locale/feeds/subscribe.properties";
+
+const NS_ERROR_MODULE_DOM = 2152923136;
+const NS_ERROR_DOM_SYNTAX_ERR = NS_ERROR_MODULE_DOM + 12;
+
+function WebContentConverter() {
+}
+WebContentConverter.prototype = {
+  convert: function WCC_convert() { },
+  asyncConvertData: function WCC_asyncConvertData() { },
+  onDataAvailable: function WCC_onDataAvailable() { },
+  onStopRequest: function WCC_onStopRequest() { },
+  
+  onStartRequest: function WCC_onStartRequest(request, context) {
+    var wccr = 
+        Cc[WCCR_CONTRACTID].
+        getService(Ci.nsIWebContentConverterService);
+    wccr.loadPreferredHandler(request);
+  },
+  
+  QueryInterface: function WCC_QueryInterface(iid) {
+    if (iid.equals(Ci.nsIStreamConverter) ||
+        iid.equals(Ci.nsIStreamListener) ||
+        iid.equals(Ci.nsISupports))
+      return this;
+    throw Cr.NS_ERROR_NO_INTERFACE;
+  }
+};
+
+var WebContentConverterFactory = {
+  createInstance: function WCCF_createInstance(outer, iid) {
+    if (outer != null)
+      throw Cr.NS_ERROR_NO_AGGREGATION;
+    return new WebContentConverter().QueryInterface(iid);
+  },
+    
+  QueryInterface: function WCC_QueryInterface(iid) {
+    if (iid.equals(Ci.nsIFactory) ||
+        iid.equals(Ci.nsISupports))
+      return this;
+    throw Cr.NS_ERROR_NO_INTERFACE;
+  }
+};
+
+function ServiceInfo(contentType, uri, name) {
+  this._contentType = contentType;
+  this._uri = uri;
+  this._name = name;
+}
+ServiceInfo.prototype = {
+  /**
+   * See nsIHandlerApp
+   */
+  get name() {
+    return this._name;
+  },
+  
+  /**
+   * See nsIHandlerApp
+   */
+  equals: function SI_equals(aHandlerApp) {
+    if (!aHandlerApp)
+      throw Cr.NS_ERROR_NULL_POINTER;
+
+    if (aHandlerApp instanceof Ci.nsIWebContentHandlerInfo &&
+        aHandlerApp.contentType == this.contentType &&
+        aHandlerApp.uri == this.uri)
+      return true;
+
+    return false;
+  },
+
+  /**
+   * See nsIWebContentHandlerInfo
+   */
+  get contentType() {
+    return this._contentType;
+  },
+
+  /**
+   * See nsIWebContentHandlerInfo
+   */
+  get uri() {
+    return this._uri;
+  },
+
+  /**
+   * See nsIWebContentHandlerInfo
+   */
+  getHandlerURI: function SI_getHandlerURI(uri) {
+    return this._uri.replace(/%s/gi, encodeURIComponent(uri));
+  },
+  
+  QueryInterface: function SI_QueryInterface(iid) {
+    if (iid.equals(Ci.nsIWebContentHandlerInfo) ||
+        iid.equals(Ci.nsISupports))
+      return this;
+    throw Cr.NS_ERROR_NO_INTERFACE;
+  }
+};
+
+function WebContentConverterRegistrar() {
+  this._contentTypes = { };
+  this._autoHandleContentTypes = { };
+}
+
+WebContentConverterRegistrar.prototype = {
+  get stringBundle() {
+    var sb = Cc["@mozilla.org/intl/stringbundle;1"].
+              getService(Ci.nsIStringBundleService).
+              createBundle(STRING_BUNDLE_URI);
+    delete WebContentConverterRegistrar.prototype.stringBundle;
+    return WebContentConverterRegistrar.prototype.stringBundle = sb;
+  },
+
+  _getFormattedString: function WCCR__getFormattedString(key, params) {
+    return this.stringBundle.formatStringFromName(key, params, params.length);
+  },
+  
+  _getString: function WCCR_getString(key) {
+    return this.stringBundle.GetStringFromName(key);
+  },
+
+  /**
+   * See nsIWebContentConverterService
+   */
+  getAutoHandler: 
+  function WCCR_getAutoHandler(contentType) {
+    contentType = this._resolveContentType(contentType);
+    if (contentType in this._autoHandleContentTypes)
+      return this._autoHandleContentTypes[contentType];
+    return null;
+  },
+  
+  /**
+   * See nsIWebContentConverterService
+   */
+  setAutoHandler:
+  function WCCR_setAutoHandler(contentType, handler) {
+    if (handler && !this._typeIsRegistered(contentType, handler.uri))
+      throw Cr.NS_ERROR_NOT_AVAILABLE;
+      
+    contentType = this._resolveContentType(contentType);
+    this._setAutoHandler(contentType, handler);
+    
+    var ps = 
+        Cc["@mozilla.org/preferences-service;1"].
+        getService(Ci.nsIPrefService);
+    var autoBranch = ps.getBranch(PREF_CONTENTHANDLERS_AUTO);
+    if (handler)
+      autoBranch.setCharPref(contentType, handler.uri);
+    else if (autoBranch.prefHasUserValue(contentType))
+      autoBranch.clearUserPref(contentType);
+     
+    ps.savePrefFile(null);
+  },
+  
+  /**
+   * Update the internal data structure (not persistent)
+   */
+  _setAutoHandler:
+  function WCCR__setAutoHandler(contentType, handler) {
+    if (handler) 
+      this._autoHandleContentTypes[contentType] = handler;
+    else if (contentType in this._autoHandleContentTypes)
+      delete this._autoHandleContentTypes[contentType];
+  },
+  
+  /**
+   * See nsIWebContentConverterService
+   */
+  getWebContentHandlerByURI:
+  function WCCR_getWebContentHandlerByURI(contentType, uri) {
+    var handlers = this.getContentHandlers(contentType, { });
+    for (var i = 0; i < handlers.length; ++i) {
+      if (handlers[i].uri == uri) 
+        return handlers[i];
+    }
+    return null;
+  },
+  
+  /**
+   * See nsIWebContentConverterService
+   */
+  loadPreferredHandler: 
+  function WCCR_loadPreferredHandler(request) {
+    var channel = request.QueryInterface(Ci.nsIChannel);
+    var contentType = this._resolveContentType(channel.contentType);
+    var handler = this.getAutoHandler(contentType);
+    if (handler) {
+      request.cancel(Cr.NS_ERROR_FAILURE);
+      
+      var webNavigation = 
+          channel.notificationCallbacks.getInterface(Ci.nsIWebNavigation);
+      webNavigation.loadURI(handler.getHandlerURI(channel.URI.spec), 
+                            Ci.nsIWebNavigation.LOAD_FLAGS_NONE, 
+                            null, null, null);
+    }      
+  },
+  
+  /**
+   * See nsIWebContentConverterService
+   */
+  removeProtocolHandler: 
+  function WCCR_removeProtocolHandler(aProtocol, aURITemplate) {
+    var eps = Cc["@mozilla.org/uriloader/external-protocol-service;1"].
+              getService(Ci.nsIExternalProtocolService);
+    var handlerInfo = eps.getProtocolHandlerInfo(aProtocol);
+    var handlers =  handlerInfo.possibleApplicationHandlers;
+    for (let i = 0; i < handlers.length; i++) {
+      try { // We only want to test web handlers
+        let handler = handlers.queryElementAt(i, Ci.nsIWebHandlerApp);
+        if (handler.uriTemplate == aURITemplate) {
+          handlers.removeElementAt(i);
+          var hs = Cc["@mozilla.org/uriloader/handler-service;1"].
+                   getService(Ci.nsIHandlerService);
+          hs.store(handlerInfo);
+          return;
+        }
+      } catch (e) { /* it wasn't a web handler */ }
+    }
+  },
+  
+  /**
+   * See nsIWebContentConverterService
+   */
+  removeContentHandler: 
+  function WCCR_removeContentHandler(contentType, uri) {
+    function notURI(serviceInfo) {
+      return serviceInfo.uri != uri;
+    }
+  
+    if (contentType in this._contentTypes) {
+      this._contentTypes[contentType] = 
+        this._contentTypes[contentType].filter(notURI);
+    }
+  },
+  
+  /**
+   *
+   */
+  _mappings: { 
+    "application/rss+xml": TYPE_MAYBE_FEED,
+    "application/atom+xml": TYPE_MAYBE_FEED,
+  },
+  
+  /**
+   * These are types for which there is a separate content converter aside 
+   * from our built in generic one. We should not automatically register
+   * a factory for creating a converter for these types.
+   */
+  _blockedTypes: {
+    "application/vnd.mozilla.maybe.feed": true,
+  },
+  
+  /**
+   * Determines the "internal" content type based on the _mappings.
+   * @param   contentType
+   * @returns The resolved contentType value. 
+   */
+  _resolveContentType: 
+  function WCCR__resolveContentType(contentType) {
+    if (contentType in this._mappings)
+      return this._mappings[contentType];
+    return contentType;
+  },
+
+  _makeURI: function(aURL, aOriginCharset, aBaseURI) {
+    var ioService = Components.classes["@mozilla.org/network/io-service;1"]
+                              .getService(Components.interfaces.nsIIOService);
+    return ioService.newURI(aURL, aOriginCharset, aBaseURI);
+  },
+
+  _checkAndGetURI:
+  function WCCR_checkAndGetURI(aURIString, aContentWindow)
+  {
+    try {
+      let baseURI = aContentWindow.document.baseURIObject;
+      var uri = this._makeURI(aURIString, null, baseURI);
+    } catch (ex) {
+      // not supposed to throw according to spec
+      return; 
+    }
+
+    // For security reasons we reject non-http(s) urls (see bug 354316),
+    // we may need to revise this once we support more content types
+    // XXX this should be a "security exception" according to spec, but that
+    // isn't defined yet.
+    if (uri.scheme != "http" && uri.scheme != "https")
+      throw("Permission denied to add " + uri.spec + " as a content or protocol handler");
+
+    // We also reject handlers registered from a different host (see bug 402287)
+    // The pref allows us to test the feature
+    var pb = Cc["@mozilla.org/preferences-service;1"].getService(Ci.nsIPrefBranch);
+    if (!pb.getBoolPref(PREF_ALLOW_DIFFERENT_HOST) &&
+        (!["http:", "https:"].includes(aContentWindow.location.protocol) ||
+         aContentWindow.location.hostname != uri.host)) {
+      throw("Permission denied to add " + uri.spec + " as a content or protocol handler");
+    }
+
+    // If the uri doesn't contain '%s', it won't be a good handler
+    if (uri.spec.indexOf("%s") < 0)
+      throw NS_ERROR_DOM_SYNTAX_ERR; 
+
+    return uri;
+  },
+
+  /**
+   * Determines if a web handler is already registered.
+   *
+   * @param aProtocol
+   *        The scheme of the web handler we are checking for.
+   * @param aURITemplate
+   *        The URI template that the handler uses to handle the protocol.
+   * @return true if it is already registered, false otherwise.
+   */
+  _protocolHandlerRegistered:
+  function WCCR_protocolHandlerRegistered(aProtocol, aURITemplate) {
+    var eps = Cc["@mozilla.org/uriloader/external-protocol-service;1"].
+              getService(Ci.nsIExternalProtocolService);
+    var handlerInfo = eps.getProtocolHandlerInfo(aProtocol);
+    var handlers =  handlerInfo.possibleApplicationHandlers;
+    for (let i = 0; i < handlers.length; i++) {
+      try { // We only want to test web handlers
+        let handler = handlers.queryElementAt(i, Ci.nsIWebHandlerApp);
+        if (handler.uriTemplate == aURITemplate)
+          return true;
+      } catch (e) { /* it wasn't a web handler */ }
+    }
+    return false;
+  },
+
+  /**
+   * See nsIWebContentHandlerRegistrar
+   */
+  registerProtocolHandler: 
+  function WCCR_registerProtocolHandler(aProtocol, aURIString, aTitle, aContentWindow) {
+    LOG("registerProtocolHandler(" + aProtocol + "," + aURIString + "," + aTitle + ")");
+
+    var uri = this._checkAndGetURI(aURIString, aContentWindow);
+
+    // If the protocol handler is already registered, just return early.
+    if (this._protocolHandlerRegistered(aProtocol, uri.spec)) {
+      return;
+    }
+
+    var browserWindow = this._getBrowserWindowForContentWindow(aContentWindow);    
+    if (PrivateBrowsingUtils.isWindowPrivate(browserWindow)) {
+      // Inside the private browsing mode, we don't want to alert the user to save
+      // a protocol handler.  We log it to the error console so that web developers
+      // would have some way to tell what's going wrong.
+      Cc["@mozilla.org/consoleservice;1"].
+      getService(Ci.nsIConsoleService).
+      logStringMessage("Web page denied access to register a protocol handler inside private browsing mode");
+      return;
+    }
+    
+    // First, check to make sure this isn't already handled internally (we don't
+    // want to let them take over, say "chrome").
+    var ios = Cc["@mozilla.org/network/io-service;1"].
+              getService(Ci.nsIIOService);
+    var handler = ios.getProtocolHandler(aProtocol);
+    if (!(handler instanceof Ci.nsIExternalProtocolHandler)) {
+      // This is handled internally, so we don't want them to register
+      // XXX this should be a "security exception" according to spec, but that
+      // isn't defined yet.
+      throw("Permission denied to add " + aURIString + "as a protocol handler");
+    }
+
+    // check if it is in the black list
+    var pb = Cc["@mozilla.org/preferences-service;1"].getService(Ci.nsIPrefBranch);
+    var allowed;
+    try {
+      allowed = pb.getBoolPref(PREF_HANDLER_EXTERNAL_PREFIX + "." + aProtocol);
+    }
+    catch (e) {
+      allowed = pb.getBoolPref(PREF_HANDLER_EXTERNAL_PREFIX + "-default");
+    }
+    if (!allowed) {
+      // XXX this should be a "security exception" according to spec
+      throw("Not allowed to register a protocol handler for " + aProtocol);
+    }
+
+    // Now Ask the user and provide the proper callback
+    var message = this._getFormattedString("addProtocolHandler",
+                                           [aTitle, uri.host, aProtocol]);
+
+    var notificationIcon = uri.prePath + "/favicon.ico";
+    var notificationValue = "Protocol Registration: " + aProtocol;
+    var addButton = {
+      label: this._getString("addProtocolHandlerAddButton"),
+      accessKey: this._getString("addHandlerAddButtonAccesskey"),
+      protocolInfo: { protocol: aProtocol, uri: uri.spec, name: aTitle },
+
+      callback:
+        function WCCR_addProtocolHandlerButtonCallback(aNotification, aButtonInfo) {
+          var protocol = aButtonInfo.protocolInfo.protocol;
+          var uri      = aButtonInfo.protocolInfo.uri;
+          var name     = aButtonInfo.protocolInfo.name;
+
+          var handler = Cc["@mozilla.org/uriloader/web-handler-app;1"].
+                        createInstance(Ci.nsIWebHandlerApp);
+          handler.name = name;
+          handler.uriTemplate = uri;
+
+          var eps = Cc["@mozilla.org/uriloader/external-protocol-service;1"].
+                    getService(Ci.nsIExternalProtocolService);
+          var handlerInfo = eps.getProtocolHandlerInfo(protocol);
+          handlerInfo.possibleApplicationHandlers.appendElement(handler, false);
+
+          // Since the user has agreed to add a new handler, chances are good
+          // that the next time they see a handler of this type, they're going
+          // to want to use it.  Reset the handlerInfo to ask before the next
+          // use.
+          handlerInfo.alwaysAskBeforeHandling = true;
+
+          var hs = Cc["@mozilla.org/uriloader/handler-service;1"].
+                   getService(Ci.nsIHandlerService);
+          hs.store(handlerInfo);
+        }
+    };
+    var browserElement = this._getBrowserForContentWindow(browserWindow, aContentWindow);
+    var notificationBox = browserWindow.gBrowser.getNotificationBox(browserElement);
+    notificationBox.appendNotification(message,
+                                       notificationValue,
+                                       notificationIcon,
+                                       notificationBox.PRIORITY_INFO_LOW,
+                                       [addButton]);
+  },
+
+  /**
+   * See nsIWebContentHandlerRegistrar
+   * If a DOM window is provided, then the request came from content, so we
+   * prompt the user to confirm the registration.
+   */
+  registerContentHandler: 
+  function WCCR_registerContentHandler(aContentType, aURIString, aTitle, aContentWindow) {
+    LOG("registerContentHandler(" + aContentType + "," + aURIString + "," + aTitle + ")");
+
+    // Check against the type blacklist.
+    // XXX this should be a "security exception" according to spec, but that
+    // isn't defined yet.
+    var contentType = this._resolveContentType(aContentType);
+    for (let blacklistType of TYPE_BLACKLIST) {
+      if (contentType == blacklistType) {
+        console.error("Unable to register content handler for prohibited MIME type %s.", contentType);
+        return;
+      }
+    }
+
+    if (aContentWindow) {
+      var uri = this._checkAndGetURI(aURIString, aContentWindow);
+  
+      var browserWindow = this._getBrowserWindowForContentWindow(aContentWindow);
+      var browserElement = this._getBrowserForContentWindow(browserWindow, aContentWindow);
+      var notificationBox = browserWindow.gBrowser.getNotificationBox(browserElement);
+      this._appendFeedReaderNotification(uri, aTitle, notificationBox);
+    }
+    else
+      this._registerContentHandler(contentType, aURIString, aTitle);
+  },
+
+  /**
+   * Returns the browser chrome window in which the content window is in
+   */
+  _getBrowserWindowForContentWindow:
+  function WCCR__getBrowserWindowForContentWindow(aContentWindow) {
+    return aContentWindow.QueryInterface(Ci.nsIInterfaceRequestor)
+                         .getInterface(Ci.nsIWebNavigation)
+                         .QueryInterface(Ci.nsIDocShellTreeItem)
+                         .rootTreeItem
+                         .QueryInterface(Ci.nsIInterfaceRequestor)
+                         .getInterface(Ci.nsIDOMWindow)
+                         .wrappedJSObject;
+  },
+
+  /**
+   * Returns the <xul:browser> element associated with the given content
+   * window.
+   *
+   * @param aBrowserWindow
+   *        The browser window in which the content window is in.
+   * @param aContentWindow
+   *        The content window. It's possible to pass a child content window
+   *        (i.e. the content window of a frame/iframe).
+   */
+  _getBrowserForContentWindow:
+  function WCCR__getBrowserForContentWindow(aBrowserWindow, aContentWindow) {
+    // This depends on pseudo APIs of browser.js and tabbrowser.xml
+    aContentWindow = aContentWindow.top;
+    var browsers = aBrowserWindow.gBrowser.browsers;
+    for (var i = 0; i < browsers.length; ++i) {
+      if (browsers[i].contentWindow == aContentWindow)
+        return browsers[i];
+    }
+  },
+
+  /**
+   * Appends a notifcation for the given feed reader details.
+   *
+   * The notification could be either a pseudo-dialog which lets
+   * the user to add the feed reader:
+   * [ [icon] Add %feed-reader-name% (%feed-reader-host%) as a Feed Reader?  (Add) [x] ]
+   *
+   * or a simple message for the case where the feed reader is already registered:
+   * [ [icon] %feed-reader-name% is already registered as a Feed Reader             [x] ]
+   *
+   * A new notification isn't appended if the given notificationbox has a
+   * notification for the same feed reader.
+   *
+   * @param aURI
+   *        The url of the feed reader as a nsIURI object
+   * @param aName
+   *        The feed reader name as it was passed to registerContentHandler
+   * @param aNotificationBox
+   *        The notification box to which a notification might be appended
+   * @return true if a notification has been appended, false otherwise.
+   */
+  _appendFeedReaderNotification:
+  function WCCR__appendFeedReaderNotification(aURI, aName, aNotificationBox) {
+    var uriSpec = aURI.spec;
+    var notificationValue = "feed reader notification: " + uriSpec;
+    var notificationIcon = aURI.prePath + "/favicon.ico";
+
+    // Don't append a new notification if the notificationbox
+    // has a notification for the given feed reader already
+    if (aNotificationBox.getNotificationWithValue(notificationValue))
+      return false;
+
+    var buttons, message;
+    if (this.getWebContentHandlerByURI(TYPE_MAYBE_FEED, uriSpec))
+      message = this._getFormattedString("handlerRegistered", [aName]);
+    else {
+      message = this._getFormattedString("addHandler", [aName, aURI.host]);
+      var self = this;
+      var addButton = {
+        _outer: self,
+        label: self._getString("addHandlerAddButton"),
+        accessKey: self._getString("addHandlerAddButtonAccesskey"),
+        feedReaderInfo: { uri: uriSpec, name: aName },
+
+        /* static */
+        callback:
+        function WCCR__addFeedReaderButtonCallback(aNotification, aButtonInfo) {
+          var uri = aButtonInfo.feedReaderInfo.uri;
+          var name = aButtonInfo.feedReaderInfo.name;
+          var outer = aButtonInfo._outer;
+
+          // The reader could have been added from another window mean while
+          if (!outer.getWebContentHandlerByURI(TYPE_MAYBE_FEED, uri))
+            outer._registerContentHandler(TYPE_MAYBE_FEED, uri, name);
+
+          // avoid reference cycles
+          aButtonInfo._outer = null;
+
+          return false;
+        }
+      };
+      buttons = [addButton];
+    }
+
+    aNotificationBox.appendNotification(message,
+                                        notificationValue,
+                                        notificationIcon,
+                                        aNotificationBox.PRIORITY_INFO_LOW,
+                                        buttons);
+    return true;
+  },
+
+  /**
+   * Save Web Content Handler metadata to persistent preferences. 
+   * @param   contentType
+   *          The content Type being handled
+   * @param   uri
+   *          The uri of the web service
+   * @param   title
+   *          The human readable name of the web service
+   *
+   * This data is stored under:
+   * 
+   *    browser.contentHandlers.type0 = content/type
+   *    browser.contentHandlers.uri0 = http://www.foo.com/q=%s
+   *    browser.contentHandlers.title0 = Foo 2.0alphr
+   */
+  _saveContentHandlerToPrefs: 
+  function WCCR__saveContentHandlerToPrefs(contentType, uri, title) {
+    var ps = 
+        Cc["@mozilla.org/preferences-service;1"].
+        getService(Ci.nsIPrefService);
+    var i = 0;
+    var typeBranch = null;
+    while (true) {
+      typeBranch = 
+        ps.getBranch(PREF_CONTENTHANDLERS_BRANCH + i + ".");
+      try {
+        typeBranch.getCharPref("type");
+        ++i;
+      }
+      catch (e) {
+        // No more handlers
+        break;
+      }
+    }
+    if (typeBranch) {
+      typeBranch.setCharPref("type", contentType);
+      var pls = 
+          Cc["@mozilla.org/pref-localizedstring;1"].
+          createInstance(Ci.nsIPrefLocalizedString);
+      pls.data = uri;
+      typeBranch.setComplexValue("uri", Ci.nsIPrefLocalizedString, pls);
+      pls.data = title;
+      typeBranch.setComplexValue("title", Ci.nsIPrefLocalizedString, pls);
+    
+      ps.savePrefFile(null);
+    }
+  },
+  
+  /**
+   * Determines if there is a type with a particular uri registered for the 
+   * specified content type already.
+   * @param   contentType
+   *          The content type that the uri handles
+   * @param   uri
+   *          The uri of the 
+   */
+  _typeIsRegistered: function WCCR__typeIsRegistered(contentType, uri) {
+    if (!(contentType in this._contentTypes))
+      return false;
+      
+    var services = this._contentTypes[contentType];
+    for (var i = 0; i < services.length; ++i) {
+      // This uri has already been registered
+      if (services[i].uri == uri)
+        return true;
+    }
+    return false;
+  },
+  
+  /**
+   * Gets a stream converter contract id for the specified content type.
+   * @param   contentType
+   *          The source content type for the conversion.
+   * @returns A contract id to construct a converter to convert between the 
+   *          contentType and *\/*.
+   */
+  _getConverterContractID: function WCCR__getConverterContractID(contentType) {
+    const template = "@mozilla.org/streamconv;1?from=%s&to=*/*";
+    return template.replace(/%s/, contentType);
+  },
+  
+  /**
+   * Register a web service handler for a content type.
+   * 
+   * @param   contentType
+   *          the content type being handled
+   * @param   uri
+   *          the URI of the web service
+   * @param   title
+   *          the human readable name of the web service
+   */
+  _registerContentHandler:
+  function WCCR__registerContentHandler(contentType, uri, title) {
+    this._updateContentTypeHandlerMap(contentType, uri, title);
+    this._saveContentHandlerToPrefs(contentType, uri, title);
+
+    if (contentType == TYPE_MAYBE_FEED) {
+      // Make the new handler the last-selected reader in the preview page
+      // and make sure the preview page is shown the next time a feed is visited
+      var pb = Cc["@mozilla.org/preferences-service;1"].
+               getService(Ci.nsIPrefService).getBranch(null);
+      pb.setCharPref(PREF_SELECTED_READER, "web");
+  
+      var supportsString = 
+        Cc["@mozilla.org/supports-string;1"].
+        createInstance(Ci.nsISupportsString);
+        supportsString.data = uri;
+      pb.setComplexValue(PREF_SELECTED_WEB, Ci.nsISupportsString,
+                         supportsString);
+      pb.setCharPref(PREF_SELECTED_ACTION, "ask");
+      this._setAutoHandler(TYPE_MAYBE_FEED, null);
+    }
+  },
+
+  /**
+   * Update the content type -> handler map. This mapping is not persisted, use
+   * registerContentHandler or _saveContentHandlerToPrefs for that purpose.
+   * @param   contentType
+   *          The content Type being handled
+   * @param   uri
+   *          The uri of the web service
+   * @param   title
+   *          The human readable name of the web service
+   */
+  _updateContentTypeHandlerMap: 
+  function WCCR__updateContentTypeHandlerMap(contentType, uri, title) {
+    if (!(contentType in this._contentTypes))
+      this._contentTypes[contentType] = [];
+
+    // Avoid adding duplicates
+    if (this._typeIsRegistered(contentType, uri)) 
+      return;
+    
+    this._contentTypes[contentType].push(new ServiceInfo(contentType, uri, title));
+    
+    if (!(contentType in this._blockedTypes)) {
+      var converterContractID = this._getConverterContractID(contentType);
+      var cr = Components.manager.QueryInterface(Ci.nsIComponentRegistrar);
+      cr.registerFactory(WCC_CLASSID, WCC_CLASSNAME, converterContractID, 
+                         WebContentConverterFactory);
+    }
+  },
+  
+  /**
+   * See nsIWebContentConverterService
+   */
+  getContentHandlers: 
+  function WCCR_getContentHandlers(contentType, countRef) {
+    countRef.value = 0;
+    if (!(contentType in this._contentTypes))
+      return [];
+    
+    var handlers = this._contentTypes[contentType];
+    countRef.value = handlers.length;
+    return handlers;
+  },
+  
+  /**
+   * See nsIWebContentConverterService
+   */
+  resetHandlersForType: 
+  function WCCR_resetHandlersForType(contentType) {
+    // currently unused within the tree, so only useful for extensions; previous
+    // impl. was buggy (and even infinite-looped!), so I argue that this is a
+    // definite improvement
+    throw Cr.NS_ERROR_NOT_IMPLEMENTED;
+  },
+  
+  /**
+   * Registers a handler from the settings on a preferences branch.
+   *
+   * @param branch
+   *        an nsIPrefBranch containing "type", "uri", and "title" preferences
+   *        corresponding to the content handler to be registered
+   */
+  _registerContentHandlerWithBranch: function(branch) {
+    /**
+     * Since we support up to six predefined readers, we need to handle gaps 
+     * better, since the first branch with user-added values will be .6
+     * 
+     * How we deal with that is to check to see if there's no prefs in the 
+     * branch and stop cycling once that's true.  This doesn't fix the case
+     * where a user manually removes a reader, but that's not supported yet!
+     */
+    var vals = branch.getChildList("");
+    if (vals.length == 0)
+      return;
+
+    try {
+      var type = branch.getCharPref("type");
+      var uri = branch.getComplexValue("uri", Ci.nsIPrefLocalizedString).data;
+      var title = branch.getComplexValue("title",
+                                         Ci.nsIPrefLocalizedString).data;
+      this._updateContentTypeHandlerMap(type, uri, title);
+    }
+    catch(ex) {
+      // do nothing, the next branch might have values
+    }
+  },
+
+  /**
+   * Load the auto handler, content handler and protocol tables from 
+   * preferences.
+   */
+  _init: function WCCR__init() {
+    var ps = 
+        Cc["@mozilla.org/preferences-service;1"].
+        getService(Ci.nsIPrefService);
+
+    var kids = ps.getBranch(PREF_CONTENTHANDLERS_BRANCH)
+                 .getChildList("");
+
+    // first get the numbers of the providers by getting all ###.uri prefs
+    var nums = [];
+    for (var i = 0; i < kids.length; i++) {
+      var match = /^(\d+)\.uri$/.exec(kids[i]);
+      if (!match)
+        continue;
+      else
+        nums.push(match[1]);
+    }
+
+    // sort them, to get them back in order
+    nums.sort(function(a, b) {return a - b;});
+
+    // now register them
+    for (var i = 0; i < nums.length; i++) {
+      var branch = ps.getBranch(PREF_CONTENTHANDLERS_BRANCH + nums[i] + ".");
+      this._registerContentHandlerWithBranch(branch);
+    }
+
+    // We need to do this _after_ registering all of the available handlers, 
+    // so that getWebContentHandlerByURI can return successfully.
+    try {
+      var autoBranch = ps.getBranch(PREF_CONTENTHANDLERS_AUTO);
+      var childPrefs = autoBranch.getChildList("");
+      for (var i = 0; i < childPrefs.length; ++i) {
+        var type = childPrefs[i];
+        var uri = autoBranch.getCharPref(type);
+        if (uri) {
+          var handler = this.getWebContentHandlerByURI(type, uri);
+          this._setAutoHandler(type, handler);
+        }
+      }
+    }
+    catch (e) {
+      // No auto branch yet, that's fine
+      //LOG("WCCR.init: There is no auto branch, benign");
+    }
+  },
+
+  /**
+   * See nsIObserver
+   */
+  observe: function WCCR_observe(subject, topic, data) {
+    var os = 
+        Cc["@mozilla.org/observer-service;1"].
+        getService(Ci.nsIObserverService);
+    switch (topic) {
+    case "app-startup":
+      os.addObserver(this, "browser-ui-startup-complete", false);
+      break;
+    case "browser-ui-startup-complete":
+      os.removeObserver(this, "browser-ui-startup-complete");
+      this._init();
+      break;
+    }
+  },
+  
+  /**
+   * See nsIFactory
+   */
+  createInstance: function WCCR_createInstance(outer, iid) {
+    if (outer != null)
+      throw Cr.NS_ERROR_NO_AGGREGATION;
+    return this.QueryInterface(iid);
+  },
+
+  classID: WCCR_CLASSID,
+
+  /**
+   * See nsISupports
+   */
+  QueryInterface: XPCOMUtils.generateQI(
+     [Ci.nsIWebContentConverterService, 
+      Ci.nsIWebContentHandlerRegistrar,
+      Ci.nsIObserver,
+      Ci.nsIFactory]),
+
+  _xpcom_categories: [{
+    category: "app-startup",
+    service: true
+  }]
+};
+
+this.NSGetFactory = XPCOMUtils.generateNSGetFactory([WebContentConverterRegistrar]);