Revert "Reland "Remove GICE (gone forever!) and PORTALLOCATOR_ENABLE_SHARED_UFRAG (enabled forever)…

webrtc/p2p/base/transportdescriptionfactory.cc

Index: webrtc/p2p/base/transportdescriptionfactory.cc
diff --git a/webrtc/p2p/base/transportdescriptionfactory.cc b/webrtc/p2p/base/transportdescriptionfactory.cc
index 7654fdfcf504a1abd5f4e97ed8db4c75eee8548f..1230ba52c18dee87447875245c289e048a47f21a 100644
--- a/webrtc/p2p/base/transportdescriptionfactory.cc
+++ b/webrtc/p2p/base/transportdescriptionfactory.cc
@@ -19,8 +19,11 @@
 
 namespace cricket {
 
+static TransportProtocol kDefaultProtocol = ICEPROTO_RFC5245;
+
 TransportDescriptionFactory::TransportDescriptionFactory()
-    : secure_(SEC_DISABLED),
+    : protocol_(kDefaultProtocol),
+      secure_(SEC_DISABLED),
       identity_(NULL) {
 }
 
@@ -29,6 +32,16 @@ TransportDescription* TransportDescriptionFactory::CreateOffer(
     const TransportDescription* current_description) const {
   rtc::scoped_ptr<TransportDescription> desc(new TransportDescription());
 
+  // Set the transport type depending on the selected protocol.
+  if (protocol_ == ICEPROTO_RFC5245) {
+    desc->transport_type = NS_JINGLE_ICE_UDP;
+  } else if (protocol_ == ICEPROTO_HYBRID) {
+    desc->transport_type = NS_JINGLE_ICE_UDP;
+    desc->AddOption(ICE_OPTION_GICE);
+  } else if (protocol_ == ICEPROTO_GOOGLE) {
+    desc->transport_type = NS_GINGLE_P2P;
+  }
+
   // Generate the ICE credentials if we don't already have them.
   if (!current_description || options.ice_restart) {
     desc->ice_ufrag = rtc::CreateRandomString(ICE_UFRAG_LENGTH);
@@ -54,14 +67,33 @@ TransportDescription* TransportDescriptionFactory::CreateAnswer(
     const TransportDescription* offer,
     const TransportOptions& options,
     const TransportDescription* current_description) const {
+  // A NULL offer is treated as a GICE transport description.
   // TODO(juberti): Figure out why we get NULL offers, and fix this upstream.
-  if (!offer) {
-    LOG(LS_WARNING) << "Failed to create TransportDescription answer " <<
-        "because offer is NULL";
+  rtc::scoped_ptr<TransportDescription> desc(new TransportDescription());
+
+  // Figure out which ICE variant to negotiate; prefer RFC 5245 ICE, but fall
+  // back to G-ICE if needed. Note that we never create a hybrid answer, since
+  // we know what the other side can support already.
+  if (offer && offer->transport_type == NS_JINGLE_ICE_UDP &&
+      (protocol_ == ICEPROTO_RFC5245 || protocol_ == ICEPROTO_HYBRID)) {
+    // Offer is ICE or hybrid, we support ICE or hybrid: use ICE.
+    desc->transport_type = NS_JINGLE_ICE_UDP;
+  } else if (offer && offer->transport_type == NS_JINGLE_ICE_UDP &&
+             offer->HasOption(ICE_OPTION_GICE) &&
+             protocol_ == ICEPROTO_GOOGLE) {
+    desc->transport_type = NS_GINGLE_P2P;
+    // Offer is hybrid, we support GICE: use GICE.
+  } else if ((!offer || offer->transport_type == NS_GINGLE_P2P) &&
+             (protocol_ == ICEPROTO_HYBRID || protocol_ == ICEPROTO_GOOGLE)) {
+    // Offer is GICE, we support hybrid or GICE: use GICE.
+    desc->transport_type = NS_GINGLE_P2P;
+  } else {
+    // Mismatch.
+    LOG(LS_WARNING) << "Failed to create TransportDescription answer "
+                       "because of incompatible transport types";
     return NULL;
   }
 
-  rtc::scoped_ptr<TransportDescription> desc(new TransportDescription());
   // Generate the ICE credentials if we don't already have them or ice is
   // being restarted.
   if (!current_description || options.ice_restart) {
@@ -125,3 +157,4 @@ bool TransportDescriptionFactory::SetSecurityInfo(
 }
 
 }  // namespace cricket
+