Bug 684893 - part2: Happy-Eyeballs + let backup socket transport retry with both IPv4+6 on IPv6-only connection attempt failure, r=mcmanus

modules/libpref/src/init/all.js

@@ -791,7 +791,7 @@ pref("network.http.connection-retry-timeout", 250);
 
 // Disable IPv6 for backup connections to workaround problems about broken
 // IPv6 connectivity.
-pref("network.http.fast-fallback-to-IPv4", false);
+pref("network.http.fast-fallback-to-IPv4", true);
 
 // default values for FTP
 // in a DSCP environment this should be 40 (0x28, or AF11), per RFC-4594,

netwerk/base/src/nsSocketTransport2.cpp

@@ -1257,6 +1257,8 @@ nsSocketTransport::RecoverFromError()
     if (mState != STATE_RESOLVING && mState != STATE_CONNECTING)
         return false;
 
+    nsresult rv;
+
     // OK to check this outside mLock
     NS_ASSERTION(!mFDconnected, "socket should not be connected");
 
@@ -1270,6 +1272,15 @@ nsSocketTransport::RecoverFromError()
 
     bool tryAgain = false;
 
+    if (mConnectionFlags & DISABLE_IPV6 &&
+        mCondition == NS_ERROR_UNKNOWN_HOST &&
+        mState == STATE_RESOLVING &&
+        !mProxyTransparentResolvesHost) {
+        SOCKET_LOG(("  trying lookup again with both ipv4/ipv6 enabled\n"));
+        mConnectionFlags &= ~DISABLE_IPV6;
+        tryAgain = true;
+    }
+
     // try next ip address only if past the resolver stage...
     if (mState == STATE_CONNECTING && mDNSRecord) {
         mDNSRecord->ReportUnusable(SocketPort());
@@ -1279,6 +1290,16 @@ nsSocketTransport::RecoverFromError()
             SOCKET_LOG(("  trying again with next ip address\n"));
             tryAgain = true;
         }
+        else if (mConnectionFlags & DISABLE_IPV6) {
+            // Drop state to closed.  This will trigger new round of DNS
+            // resolving bellow.
+            // XXX Here should idealy be set now non-existing flag DISABLE_IPV4
+            SOCKET_LOG(("  failed to connect all ipv4 hosts,"
+                        " trying lookup/connect again with both ipv4/ipv6\n"));
+            mState = STATE_CLOSED;
+            mConnectionFlags &= ~DISABLE_IPV6;
+            tryAgain = true;
+        }
     }
 
 #if defined(XP_WIN) || defined(MOZ_PLATFORM_MAEMO)
@@ -1296,7 +1317,6 @@ nsSocketTransport::RecoverFromError()
 
     // prepare to try again.
     if (tryAgain) {
-        nsresult rv;
         PRUint32 msg;
 
         if (mState == STATE_CONNECTING) {