Bug 1540658 - Web Authentication - U2FTokenManager must obey the IPC state machine r=keeler

In Bug 1448408 ("Don't listen to visibility events"), I changed `U2FTokenManager::
ClearTransaction` to send aborts, to handle the new visibility states. However,

`WebAuthnTransactionParent::ActorDestroy` is called at the conclusion of IPC
shutdown, which calls `MaybeClearTransaction` in `U2FTokenManager`, which calls
ClearTransaction, which then tries to send an Abort, which is a state machine
failure since we just shut the IPC down.

This patch creates a new `AbortOngoingTransaction` method which is used
to send the aborts instead of shoehorning that into `ClearTransaction`, reverting
`ClearTransaction` back to the prior form, and instead changes `Register` and
`Sign` to call the new method.

Differential Revision: https://phabricator.services.mozilla.com/D25687

--HG--
extra : moz-landing-system : lando

dom/webauthn/U2FTokenManager.cpp

@@ -166,6 +166,15 @@ void U2FTokenManager::AbortTransaction(const uint64_t& aTransactionId,
   ClearTransaction();
 }
 
+void U2FTokenManager::AbortOngoingTransaction() {
+  if (mLastTransactionId > 0 && mTransactionParent) {
+    // Send an abort to any other ongoing transaction
+    Unused << mTransactionParent->SendAbort(mLastTransactionId,
+                                            NS_ERROR_DOM_ABORT_ERR);
+  }
+  ClearTransaction();
+}
+
 void U2FTokenManager::MaybeClearTransaction(
     PWebAuthnTransactionParent* aParent) {
   // Only clear if we've been requested to do so by our current transaction
@@ -176,12 +185,9 @@ void U2FTokenManager::MaybeClearTransaction(
 }
 
 void U2FTokenManager::ClearTransaction() {
-  if (mLastTransactionId > 0 && mTransactionParent) {
+  if (mLastTransactionId) {
     // Remove any prompts we might be showing for the current transaction.
     SendPromptNotification(kCancelPromptNotifcation, mLastTransactionId);
-    // Send an abort to any other ongoing transaction
-    Unused << mTransactionParent->SendAbort(mLastTransactionId,
-                                            NS_ERROR_DOM_ABORT_ERR);
   }
 
   mTransactionParent = nullptr;
@@ -271,7 +277,7 @@ void U2FTokenManager::Register(
     const WebAuthnMakeCredentialInfo& aTransactionInfo) {
   MOZ_LOG(gU2FTokenManagerLog, LogLevel::Debug, ("U2FAuthRegister"));
 
-  ClearTransaction();
+  AbortOngoingTransaction();
   mTransactionParent = aTransactionParent;
   mTokenManagerImpl = GetTokenManagerImpl();
 
@@ -368,7 +374,7 @@ void U2FTokenManager::Sign(PWebAuthnTransactionParent* aTransactionParent,
                            const WebAuthnGetAssertionInfo& aTransactionInfo) {
   MOZ_LOG(gU2FTokenManagerLog, LogLevel::Debug, ("U2FAuthSign"));
 
-  ClearTransaction();
+  AbortOngoingTransaction();
   mTransactionParent = aTransactionParent;
   mTokenManagerImpl = GetTokenManagerImpl();
 

dom/webauthn/U2FTokenManager.h

@@ -49,6 +49,7 @@ class U2FTokenManager final : public nsIU2FTokenManager {
   ~U2FTokenManager() {}
   RefPtr<U2FTokenTransport> GetTokenManagerImpl();
   void AbortTransaction(const uint64_t& aTransactionId, const nsresult& aError);
+  void AbortOngoingTransaction();
   void ClearTransaction();
   // Step two of "Register", kicking off the actual transaction.
   void DoRegister(const WebAuthnMakeCredentialInfo& aInfo,