Add basic versioning check to Chromoting's plugin/JS code.

Fixup order of elements in the ScriptableObject interface header. It's supposed to match the .CC file but had gotten seriously out of sync.

BUG=none
TEST=manual


Review URL: http://codereview.chromium.org/7065036

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@86655 0039d316-1c4b-4281-b951-d872f2087c98

remoting/client/appengine/static_files/chromoting_session.js

@@ -6,6 +6,16 @@
 // Only the most recent <n> lines are displayed.
 var MAX_DEBUG_LOG_SIZE = 1000;
 
+// Chromoting session API version (for this javascript).
+// This is compared with the plugin API version to verify that they are
+// compatible.
+chromoting.apiVersion = 1;
+
+// The oldest API version that we support.
+// This will differ from the |apiVersion| if we decide to maintain backward
+// compatibility with older API versions.
+chromoting.apiMinVersion = 1;
+
 // Message id so that we can identify (and ignore) message fade operations for
 // old messages.  This starts at 1 and is incremented for each new message.
 chromoting.messageId = 1;
@@ -93,6 +103,11 @@ function sendIq(msg) {
            "&host_jid=" + encodeURIComponent(chromoting.hostjid));
 }
 
+function checkVersion(plugin) {
+  return chromoting.apiVersion >= plugin.apiMinVersion &&
+      plugin.apiVersion >= chromoting.apiMinVersion;
+}
+
 function init() {
   // Kick off the connection.
   var plugin = document.getElementById('chromoting');
@@ -123,6 +138,12 @@ function init() {
   plugin.desktopSizeUpdate = desktopSizeChanged;
   plugin.loginChallenge = loginChallengeCallback;
 
+  if (!checkVersion(plugin)) {
+    // TODO(garykac): We need better messaging here. Perhaps an install link.
+    setClientStateMessage("Out of date. Please re-install.");
+    return;
+  }
+
   addToDebugLog('Connect to ' + chromoting.hostname + ' as user ' +
                 chromoting.username);
 

remoting/client/plugin/chromoting_scriptable_object.cc

@@ -18,6 +18,8 @@ namespace remoting {
 
 namespace {
 
+const char kApiVersionAttribute[] = "apiVersion";
+const char kApiMinVersionAttribute[] = "apiMinVersion";
 const char kConnectionInfoUpdate[] = "connectionInfoUpdate";
 const char kDebugInfo[] = "debugInfo";
 const char kDesktopHeight[] = "desktopHeight";
@@ -48,6 +50,14 @@ void ChromotingScriptableObject::Init() {
   // Property addition order should match the interface description at the
   // top of chromoting_scriptable_object.h.
 
+  // Plugin API version.
+  // This should be incremented whenever the API interface changes.
+  AddAttribute(kApiVersionAttribute, Var(1));
+
+  // This should be updated whenever we remove support for an older version
+  // of the API.
+  AddAttribute(kApiMinVersionAttribute, Var(1));
+
   // Connection status.
   AddAttribute(kStatusAttribute, Var(STATUS_UNKNOWN));
 

remoting/client/plugin/chromoting_scriptable_object.h

@@ -7,6 +7,16 @@
 //
 // interface ChromotingScriptableObject {
 //
+//   // Chromoting session API version (for this plugin).
+//   // This is compared with the javascript API version to verify that they are
+//   // compatible.
+//   readonly attribute unsigned short apiVersion;
+//
+//   // The oldest API version that we support.
+//   // This will differ from |apiVersion| if we decide to maintain backward
+//   // compatibility with older API versions.
+//   readonly attribute unsigned short apiMinVersion;
+//
 //   // Dimension of the desktop area.
 //   readonly attribute int desktopWidth;
 //   readonly attribute int desktopHeight;

remoting/webapp/me2mom/remoting_session.js

@@ -5,8 +5,19 @@
 // Maximum numer of lines to record in the debug log.
 // Only the most recent <n> lines are displayed.
 var MAX_DEBUG_LOG_SIZE = 1000;
+
 var remoting = chrome.extension.getBackgroundPage().remoting;
 
+// Chromoting session API version (for this javascript).
+// This is compared with the plugin API version to verify that they are
+// compatible.
+remoting.apiVersion = 1;
+
+// The oldest API version that we support.
+// This will differ from the |apiVersion| if we maintain backward
+// compatibility with older API versions.
+remoting.apiMinVersion = 1;
+
 // Message id so that we can identify (and ignore) message fade operations for
 // old messages.  This starts at 1 and is incremented for each new message.
 remoting.messageId = 1;
@@ -95,6 +106,11 @@ function sendIq(msg) {
            '&host_jid=' + encodeURIComponent(remoting.hostjid));
 }
 
+function checkVersion(plugin) {
+  return remoting.apiVersion >= plugin.apiMinVersion &&
+      plugin.apiVersion >= remoting.apiMinVersion;
+}
+
 function init() {
   // Kick off the connection.
   var plugin = document.getElementById('remoting');
@@ -116,6 +132,12 @@ function init() {
   plugin.desktopSizeUpdate = desktopSizeChanged;
   plugin.loginChallenge = loginChallengeCallback;
 
+  if (!checkVersion(plugin)) {
+    // TODO(garykac): We need better messaging here. Perhaps an install link.
+    setClientStateMessage("Out of date. Please re-install.");
+    return;
+  }
+
   addToDebugLog('Connect as user ' + remoting.username);
 
   // TODO(garykac): Clean exit if |connect| isn't a function.