[link prober] print out error code message when sendHeartbeat fails (#266) (#276)

Summary:
Fixes # (issue)
Print out error code message when sendHeartbeat fails.

sign-off: Jing Zhang [email protected]

Co-authored-by: Jing Zhang <[email protected]>

Author: mssonicbld

src/link_prober/LinkProber.cpp

@@ -333,7 +333,7 @@ void LinkProber::sendHeartbeat(bool forceSend)
         mStream.write_some(boost::asio::buffer(mTxBuffer.data(), mTxPacketSize), errorCode);
 
         if (errorCode) {
-            MUXLOGTRACE(mMuxPortConfig.getPortName() + ": Failed to send heartbeat!");
+            MUXLOGTRACE(mMuxPortConfig.getPortName() + ": Failed to send heartbeat! Error code: " + errorCode.message());
         } else {
             MUXLOGTRACE(mMuxPortConfig.getPortName() + ": Done sending data");
         }
@@ -458,6 +458,7 @@ void LinkProber::handleRecv(
             }
         } else {
             // Unknown ICMP packet, ignore.
+            MUXLOGTRACE(mMuxPortConfig.getPortName() + ": Failed to receive heartbeat! Error code: " + errorCode.message());
         }
         // start another receive to consume as much as possible of backlog packets if any
         startRecv();

test/LinkProberTest.cpp

@@ -337,4 +337,15 @@ TEST_F(LinkProberTest, InitializeException)
     EXPECT_THROW(initialize(), common::SocketErrorException);
 }
 
+TEST_F(LinkProberTest, LogErrorCodeMessage)
+{
+    EXPECT_THROW(simulateBadFileDescriptor(), boost::system::system_error);
+
+    try {
+        simulateBadFileDescriptor();
+    } catch (const boost::system::system_error& e) {
+        EXPECT_EQ(e.code().value(), boost::system::errc::bad_file_descriptor);
+        EXPECT_EQ(e.code().message(), "Bad file descriptor");
+    }
+}
 } /* namespace test */

test/LinkProberTest.h

@@ -61,6 +61,10 @@ class LinkProberTest: public ::testing::Test
     void initTxBufferTlvSendProbe() {mLinkProber.initTxBufferTlvSendProbe();}
     void initTxBufferSentinel() {mLinkProber.initTxBufferTlvSentinel();}
 
+    void simulateBadFileDescriptor() {
+        throw boost::system::system_error(make_error_code(boost::system::errc::bad_file_descriptor));
+    }
+
     boost::asio::io_service mIoService;
     common::MuxConfig mMuxConfig;
     std::shared_ptr<FakeDbInterface> mDbInterfacePtr;