Reject the descriptions that attempt to change the order of m= sections

webrtc/pc/peerconnectioninterface_unittest.cc

 /*
  *  Copyright 2012 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
+#include <algorithm>
 #include <memory>
 #include <sstream>
 #include <string>
 #include <utility>
 
 #include "webrtc/api/audio_codecs/builtin_audio_decoder_factory.h"
 #include "webrtc/api/audio_codecs/builtin_audio_encoder_factory.h"
 #include "webrtc/api/jsepsessiondescription.h"
 #include "webrtc/api/mediastreaminterface.h"
 #include "webrtc/api/peerconnectioninterface.h"
@@ skipping 3803 matching lines @@
   CreatePeerConnection();
   // Creating answer fails because the remote description is unset.
   std::unique_ptr<SessionDescriptionInterface> answer;
   EXPECT_FALSE(DoCreateAnswer(&answer, nullptr));
 
   // Createing answer succeeds when the remote description is set.
   CreateOfferAsRemoteDescription();
   EXPECT_TRUE(DoCreateAnswer(&answer, nullptr));
 }
 
+// Test that an error is returned if a description is applied that doesn't
+// respect the order of existing media sections.
+TEST_F(PeerConnectionInterfaceTest,
+       MediaSectionOrderEnforcedForSubsequentOffers) {
+  CreatePeerConnection();
+  FakeConstraints constraints;
+  constraints.SetMandatoryReceiveAudio(true);
+  constraints.SetMandatoryReceiveVideo(true);
+  std::unique_ptr<SessionDescriptionInterface> offer;
+  ASSERT_TRUE(DoCreateOffer(&offer, &constraints));
+  EXPECT_TRUE(DoSetRemoteDescription(std::move(offer)));
+
+  std::unique_ptr<SessionDescriptionInterface> answer;
+  ASSERT_TRUE(DoCreateAnswer(&answer, nullptr));
+  EXPECT_TRUE(DoSetLocalDescription(std::move(answer)));
+
+  // A remote offer with different m=line order should be rejected.
+  ASSERT_TRUE(DoCreateOffer(&offer, &constraints));
+  std::reverse(offer->description()->contents().begin(),
+               offer->description()->contents().end());
+  std::reverse(offer->description()->transport_infos().begin(),
+               offer->description()->transport_infos().end());
+  EXPECT_FALSE(DoSetRemoteDescription(std::move(offer)));
+
+  // A subsequent local offer with different m=line order should be rejected.
+  ASSERT_TRUE(DoCreateOffer(&offer, &constraints));
+  std::reverse(offer->description()->contents().begin(),
+               offer->description()->contents().end());
+  std::reverse(offer->description()->transport_infos().begin(),
+               offer->description()->transport_infos().end());
+  EXPECT_FALSE(DoSetLocalDescription(std::move(offer)));
+}
+
 class PeerConnectionMediaConfigTest : public testing::Test {
  protected:
   void SetUp() override {
     pcf_ = PeerConnectionFactoryForTest::CreatePeerConnectionFactoryForTest();
     pcf_->Initialize();
   }
   const cricket::MediaConfig TestCreatePeerConnection(
       const PeerConnectionInterface::RTCConfiguration& config,
       const MediaConstraintsInterface* constraints) {
     rtc::scoped_refptr<PeerConnectionInterface> pc(pcf_->CreatePeerConnection(
@@ skipping 100 matching lines @@
   EXPECT_NE(a, f);
 
   PeerConnectionInterface::RTCConfiguration g;
   g.disable_ipv6 = true;
   EXPECT_NE(a, g);
 
   PeerConnectionInterface::RTCConfiguration h(
       PeerConnectionInterface::RTCConfigurationType::kAggressive);
   EXPECT_NE(a, h);
 }