Add support for loopback route on emulated endpoints

Bug: b/172995851
Change-Id: I70b5ec6cd84784dcc452e8f96a02f4be849fa0f7
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/192920
Reviewed-by: Mirko Bonadei <[email protected]>
Commit-Queue: Artem Titov <[email protected]>
Cr-Commit-Position: refs/heads/master@{#32596}

Author: Artem Titov

test/network/network_emulation.cc

@@ -469,7 +469,11 @@ void EmulatedEndpointImpl::SendPacket(const rtc::SocketAddress& from,
         packet.arrival_time, clock_->CurrentTime(), packet.to.ipaddr(),
         DataSize::Bytes(packet.ip_packet_size()), stats_gathering_mode_);
 
-    router_.OnPacketReceived(std::move(packet));
+    if (packet.to.ipaddr() == peer_local_addr_) {
+      OnPacketReceived(std::move(packet));
+    } else {
+      router_.OnPacketReceived(std::move(packet));
+    }
   });
 }
 

test/network/network_emulation_unittest.cc

@@ -554,5 +554,19 @@ TEST_F(NetworkEmulationManagerThreeNodesRoutingTest,
   SendPacketsAndValidateDelivery();
 }
 
+TEST(NetworkEmulationManagerTest, EndpointLoopback) {
+  NetworkEmulationManagerImpl network_manager(TimeMode::kSimulated);
+  auto endpoint = network_manager.CreateEndpoint(EmulatedEndpointConfig());
+
+  MockReceiver receiver;
+  EXPECT_CALL(receiver, OnPacketReceived(::testing::_)).Times(1);
+  ASSERT_EQ(endpoint->BindReceiver(80, &receiver), 80);
+
+  endpoint->SendPacket(rtc::SocketAddress(endpoint->GetPeerLocalAddress(), 80),
+                       rtc::SocketAddress(endpoint->GetPeerLocalAddress(), 80),
+                       "Hello");
+  network_manager.time_controller()->AdvanceTime(TimeDelta::Seconds(1));
+}
+
 }  // namespace test
 }  // namespace webrtc