Allow rtp::Packet::*RawExtension to take 0 as an extension id

webrtc/modules/rtp_rtcp/source/rtp_packet_unittest.cc

 /*
  *  Copyright (c) 2016 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 "webrtc/modules/rtp_rtcp/source/rtp_packet_received.h"
 #include "webrtc/modules/rtp_rtcp/source/rtp_packet_to_send.h"
 
 #include "webrtc/base/random.h"
 #include "webrtc/modules/rtp_rtcp/source/rtp_header_extension.h"
 #include "webrtc/modules/rtp_rtcp/source/rtp_header_extensions.h"
 #include "webrtc/test/gmock.h"
 #include "webrtc/test/gtest.h"
 
-using testing::ElementsAreArray;
-using testing::make_tuple;
-
 namespace webrtc {
 namespace {
+using ::testing::ElementsAreArray;
+using ::testing::IsEmpty;
+using ::testing::make_tuple;
+
 constexpr int8_t kPayloadType = 100;
 constexpr uint32_t kSsrc = 0x12345678;
 constexpr uint16_t kSeqNum = 88;
 constexpr uint32_t kTimestamp = 0x65431278;
 constexpr uint8_t kTransmissionOffsetExtensionId = 1;
 constexpr uint8_t kAudioLevelExtensionId = 9;
 constexpr int32_t kTimeOffset = 0x56ce;
 constexpr bool kVoiceActive = true;
 constexpr uint8_t kAudioLevel = 0x5a;
 constexpr size_t kMaxPaddingSize = 224u;
@@ skipping 322 matching lines @@
   EXPECT_TRUE(packet.HasRawExtension(kTransmissionOffsetExtensionId));
 
   int32_t time_offset = 0;
   auto raw_extension = packet.GetRawExtension(kTransmissionOffsetExtensionId);
   EXPECT_EQ(raw_extension.size(), TransmissionOffset::kValueSizeBytes);
   EXPECT_TRUE(TransmissionOffset::Parse(raw_extension, &time_offset));
 
   EXPECT_EQ(time_offset, kTimeOffset);
 }
 
+TEST(RtpPacketTest, RawExtensionFunctionsAcceptZeroIdAndReturnFalse) {
+  RtpPacketReceived::ExtensionManager extensions;
+  RtpPacketReceived packet(&extensions);
+  // Use ExtensionManager to set kInvalidId to 0 to demonstrate natural way for
+  // using zero value as a parameter to Packet::*RawExtension functions.
+  const int kInvalidId = extensions.GetId(TransmissionOffset::kId);
+  ASSERT_EQ(kInvalidId, 0);
+
+  ASSERT_TRUE(packet.Parse(kPacket, sizeof(kPacket)));
+
+  EXPECT_FALSE(packet.HasRawExtension(kInvalidId));
+  EXPECT_THAT(packet.GetRawExtension(kInvalidId), IsEmpty());
+  const uint8_t kExtension[] = {'e', 'x', 't'};
+  EXPECT_FALSE(packet.SetRawExtension(kInvalidId, kExtension));
+  EXPECT_THAT(packet.AllocateRawExtension(kInvalidId, 3), IsEmpty());
+}
+
 }  // namespace webrtc