Merge pull request #72 from richardschneider/traffic

Multicast traffic logger
richardschneider · Jul 15, 2019 · a5b730b · a5b730b
2 parents e53c5d9 + d479d16
commit a5b730b
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Showing 5 changed files with 97 additions and 6 deletions.
diff --git a/Mdns.sln b/Mdns.sln
@@ -24,6 +24,8 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Spike", "Spike\Spike.csproj
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Browser", "Browser\Browser.csproj", "{A77BEF8C-440E-46F7-ACFC-5EF06EFCA4BA}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "traffic", "traffic\traffic.csproj", "{5E51D502-05E1-4A45-A8D6-6FB3E295D798}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -48,6 +50,10 @@ Global
 		{A77BEF8C-440E-46F7-ACFC-5EF06EFCA4BA}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{A77BEF8C-440E-46F7-ACFC-5EF06EFCA4BA}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{A77BEF8C-440E-46F7-ACFC-5EF06EFCA4BA}.Release|Any CPU.Build.0 = Release|Any CPU
+		{5E51D502-05E1-4A45-A8D6-6FB3E295D798}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{5E51D502-05E1-4A45-A8D6-6FB3E295D798}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{5E51D502-05E1-4A45-A8D6-6FB3E295D798}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{5E51D502-05E1-4A45-A8D6-6FB3E295D798}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE

diff --git a/src/MulticastService.cs b/src/MulticastService.cs
@@ -104,6 +104,14 @@ static MulticastService()
         /// </remarks>
         public event EventHandler<MessageEventArgs> AnswerReceived;
 
+        /// <summary>
+        ///   Raised when a DNS message is received that cannot be decoded.
+        /// </summary>
+        /// <value>
+        ///   The DNS message as a byte array.
+        /// </value>
+        public event EventHandler<byte[]> MalformedMessage;
+
         /// <summary>
         ///   Raised when one or more network interfaces are discovered. 
         /// </summary>
@@ -603,8 +611,12 @@ void Send(Message msg, bool checkDuplicate, IPEndPoint remoteEndPoint = null)
         ///   Multicast DNS messages received with an OPCODE or RCODE other than zero 	
         ///   are silently ignored.	
         ///   </para>	
+        ///   <para>
+        ///   If the message cannot be decoded, then the <see cref="MalformedMessage"/>
+        ///   event is raised.
+        ///   </para>
         /// </remarks>
-        void OnDnsMessage(object sender, UdpReceiveResult result)
+        public void OnDnsMessage(object sender, UdpReceiveResult result)
         {
             // If recently received, then ignore.
             if (!receivedMessages.TryAdd(result.Buffer))
@@ -620,6 +632,7 @@ void OnDnsMessage(object sender, UdpReceiveResult result)
             catch (Exception e)
             {
                 log.Warn("Received malformed message", e);
+                MalformedMessage?.Invoke(this, result.Buffer);
                 return; // eat the exception
             }
 

diff --git a/test/MulticastServiceTest.cs b/test/MulticastServiceTest.cs
@@ -529,10 +529,10 @@ public async Task DuplicateResponse()
             using (var mdns = new MulticastService())
             {
                 var answerCount = 0;
-                mdns.NetworkInterfaceDiscovered += async (s, e) =>
+                mdns.NetworkInterfaceDiscovered += (s, e) =>
                 {
                     mdns.SendQuery(service);
-                    await Task.Delay(250);
+                    Thread.Sleep(250);
                     mdns.SendQuery(service);
                 };
                 mdns.QueryReceived += (s, e) =>
@@ -572,10 +572,10 @@ public async Task NoDuplicateResponse()
             using (var mdns = new MulticastService())
             {
                 var answerCount = 0;
-                mdns.NetworkInterfaceDiscovered += async (s, e) =>
+                mdns.NetworkInterfaceDiscovered += (s, e) =>
                 {
                     mdns.SendQuery(service);
-                    await Task.Delay(2000);
+                    Thread.Sleep(2000);
                     mdns.SendQuery(service);
                 };
                 mdns.QueryReceived += (s, e) =>
@@ -601,7 +601,7 @@ public async Task NoDuplicateResponse()
                     };
                 };
                 mdns.Start();
-                await Task.Delay(3000);
+                await Task.Delay(5000);
                 Assert.AreEqual(2, answerCount);
             }
         }
@@ -624,5 +624,22 @@ public void Multiple_Listeners()
                 Assert.IsTrue(ready2.WaitOne(TimeSpan.FromSeconds(1)), "ready2 timeout");
             }
         }
+
+        [TestMethod]
+        public void MalformedMessage()
+        {
+            byte[] malformedMessage = null;
+            using (var mdns = new MulticastService())
+            {
+                mdns.MalformedMessage += (s, e) => malformedMessage = e;
+
+                var msg = new byte[] { 0xff };
+                var endPoint = new IPEndPoint(IPAddress.Loopback, 5353);
+                var udp = new UdpReceiveResult(msg, endPoint);
+                mdns.OnDnsMessage(this, udp);
+
+                CollectionAssert.AreEqual(msg, malformedMessage);
+            }
+        }
     }
 }
diff --git a/traffic/Program.cs b/traffic/Program.cs
@@ -0,0 +1,43 @@
+using Makaretu.Dns;
+using System;
+
+namespace traffic
+{
+    class Program
+    {
+        static readonly object ttyLock = new object();
+
+        static void Main(string[] args)
+        {
+            var mdns = new MulticastService();
+            mdns.NetworkInterfaceDiscovered += (s, e)
+                => mdns.SendQuery(ServiceDiscovery.ServiceName, type: DnsType.PTR);
+            mdns.AnswerReceived += OnGoodDnsMessage;
+            mdns.QueryReceived += OnGoodDnsMessage;
+            mdns.MalformedMessage += OnBadDnsMessage;
+            mdns.Start();
+            Console.ReadKey();
+        }
+
+        private static void OnBadDnsMessage(object sender, byte[] packet)
+        {
+            lock (ttyLock)
+            {
+                Console.WriteLine(">>> {0:O} <<<", DateTime.Now);
+                Console.WriteLine("Malformed message (base64)");
+                Console.WriteLine(Convert.ToBase64String(packet));
+            }
+
+            Environment.Exit(1);
+        }
+
+        private static void OnGoodDnsMessage(object sender, MessageEventArgs e)
+        {
+            lock (ttyLock)
+            {
+                Console.WriteLine("=== {0:O} ===", DateTime.Now);
+                Console.WriteLine(e.Message.ToString());
+            }
+        }
+    }
+}
diff --git a/traffic/traffic.csproj b/traffic/traffic.csproj
@@ -0,0 +1,12 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>netcoreapp2.2</TargetFramework>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\src\Mdns.csproj" />
+  </ItemGroup>
+
+</Project>