Fix compatibility with authenticated proxies

It's not clear when this became an issue, but our usual background HTTP
requests (set that way to avoid triggering auth prompts when saving from
websites) weren't triggering proxy authentication dialogs, which was breaking
most network activity in Standalone. To fix this, we now make a foreground
request at startup to a file on S3 and resolve the Zotero.proxyAuthComplete
promise when we're done. Any network requests that want to wait for proxy
authentication can wait for that promise.

This behavior can be disabled via the triggerProxyAuthentication hidden pref.

chrome/content/zotero/xpcom/http.js

@@ -440,6 +440,53 @@ Zotero.HTTP = new function() {
 		return xmlhttp;
 	}
 	
+	
+	/**
+	 * Make a foreground HTTP request in order to trigger a proxy authentication
+	 * dialog in Standalone
+	 *
+	 * Other Zotero.HTTP requests are background requests by default, and
+	 * background requests don't trigger a proxy auth prompt, so we make a
+	 * foreground request on startup and resolve the promise
+	 * Zotero.proxyAuthComplete when we're done. Any network requests that want
+	 * to wait for proxy authentication can wait for that promise.
+	 */
+	this.triggerProxyAuth = function () {
+		if (!Zotero.isStandalone
+				|| !Zotero.Prefs.get("triggerProxyAuthentication")
+				|| Zotero.HTTP.browserIsOffline()) {
+			Zotero.proxyAuthComplete = Q();
+			return false;
+		}
+		
+		var deferred = Q.defer();
+		Zotero.proxyAuthComplete = deferred.promise;
+		
+		var uri = ZOTERO_CONFIG.PROXY_AUTH_URL;
+		
+		Zotero.debug("HTTP GET " + uri);
+		
+		var xmlhttp = Components.classes["@mozilla.org/xmlextras/xmlhttprequest;1"]
+					.createInstance();
+		xmlhttp.open("GET", uri, true);
+		
+		xmlhttp.channel.loadFlags |= Components.interfaces.nsIRequest.LOAD_BYPASS_CACHE;
+		
+		var useMethodjit = Components.utils.methodjit;
+		/** @ignore */
+		xmlhttp.onreadystatechange = function() {
+			Components.utils.methodjit = useMethodjit;
+			_stateChange(xmlhttp, function (xmlhttp) {
+				Zotero.debug("Proxy auth request completed with status "
+					+ xmlhttp.status + ": " + xmlhttp.responseText);
+				deferred.resolve();
+			});
+		};
+		xmlhttp.send(null);
+		return xmlhttp;
+	}
+	
+	
 	//
 	// WebDAV methods
 	//

chrome/content/zotero/xpcom/schema.js

@@ -474,11 +474,18 @@ Zotero.Schema = new function(){
 				var deferred = Q.defer();
 				if (updated) {
 					if (Zotero.Prefs.get('automaticScraperUpdates')) {
-						Zotero.Schema.updateFromRepository(2, function () deferred.resolve());
+						Zotero.proxyAuthComplete
+						.then(function () {
+							Zotero.Schema.updateFromRepository(2, function () deferred.resolve());
+						})
 					}
 				}
 				else {
-					Zotero.Schema.updateFromRepository(false, function () deferred.resolve());
+					Zotero.proxyAuthComplete
+					.then(function () {
+						Zotero.Schema.updateFromRepository(false, function () deferred.resolve());
+					})
+					.done();
 				}
 				return deferred.promise;
 			}

chrome/content/zotero/xpcom/zotero.js

@@ -31,6 +31,7 @@ const ZOTERO_CONFIG = {
 	REPOSITORY_RETRY_INTERVAL: 3600, // 1 hour
 	BASE_URI: 'http://zotero.org/',
 	WWW_BASE_URL: 'http://www.zotero.org/',
+	PROXY_AUTH_URL: 'http://zotero.org.s3.amazonaws.com/proxy-auth',
 	SYNC_URL: 'https://sync.zotero.org/',
 	API_URL: 'https://api.zotero.org/',
 	API_VERSION: 2,
@@ -544,6 +545,8 @@ Components.utils.import("resource://gre/modules/Services.jsm");
 		
 		if(!_initDB()) return false;
 		
+		Zotero.HTTP.triggerProxyAuth();
+		
 		// Add notifier queue callbacks to the DB layer
 		Zotero.DB.addCallback('begin', Zotero.Notifier.begin);
 		Zotero.DB.addCallback('commit', Zotero.Notifier.commit);

chrome/content/zotero/zoteroPane.js

@@ -415,7 +415,9 @@ var ZoteroPane = new function()
 		
 		// Auto-sync on pane open
 		if (Zotero.Prefs.get('sync.autoSync')) {
-			setTimeout(function () {
+			Zotero.proxyAuthComplete
+			.delay(1000)
+			.then(function () {
 				if (!Zotero.Sync.Server.enabled) {
 					Zotero.debug('Sync not enabled -- skipping auto-sync', 4);
 					return;
@@ -432,7 +434,8 @@ var ZoteroPane = new function()
 				}
 				
 				Zotero.Sync.Runner.sync(true);
-			}, 1000);
+			})
+			.done();
 		}
 		
 		// Set sync icon to spinning or not

defaults/preferences/zotero.js

@@ -21,6 +21,7 @@ pref("extensions.zotero.debug.level",5);
 pref("extensions.zotero.debug.time", false);
 pref("extensions.zotero.automaticScraperUpdates",true);
 pref("extensions.zotero.zoteroDotOrgVersionHeader", true);
+pref("extensions.zotero.triggerProxyAuthentication", true);
 pref("extensions.zotero.cacheTranslatorData",true);
 pref("extensions.zotero.showIn", 1);
 pref("extensions.zotero.statusBarIcon", 2);