[release/2.0.0] Port SmtpClient fixes to 2.0 (dotnet#24727)

* Fix null ref exception when Dispose'ing SmtpClient (dotnet#24521) If SmtpClient is disposed after a failed send and no successful sends, it attempts to call Close on a null NetworkStream field. * Fix hang when SmtpClient.SendAsync fails to connect (dotnet#24536) If Send{Mail}Async fails to connect, an exception gets thrown/eaten, and the completion callback is never invoked / the returned Task is never completed.
mikem8361 · Oct 30, 2017 · f997049 · f997049
1 parent 6ae66ab
commit f997049
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Showing 2 changed files with 25 additions and 7 deletions.
diff --git a/src/System.Net.Mail/src/System/Net/Mail/SmtpConnection.cs b/src/System.Net.Mail/src/System/Net/Mail/SmtpConnection.cs
@@ -152,7 +152,7 @@ internal void ReleaseConnection()
                             _channelBindingToken.Close();
                         }
 
-                        _networkStream.Close();
+                        _networkStream?.Close();
                         _tcpClient.Dispose();
                     }
 
@@ -439,11 +439,11 @@ private void InitializeConnection()
                 IAsyncResult result = _connection.BeginInitializeConnection(_host, _port, InitializeConnectionCallback, this);
                 if (result.CompletedSynchronously)
                 {
-                    _connection.EndInitializeConnection(result);
-                    if (NetEventSource.IsEnabled) NetEventSource.Info(this, "Connect returned");
-
                     try
                     {
+                        _connection.EndInitializeConnection(result);
+                        if (NetEventSource.IsEnabled) NetEventSource.Info(this, "Connect returned");
+
                         Handshake();
                     }
                     catch (Exception e)
@@ -458,11 +458,11 @@ private static void InitializeConnectionCallback(IAsyncResult result)
                 if (!result.CompletedSynchronously)
                 {
                     ConnectAndHandshakeAsyncResult thisPtr = (ConnectAndHandshakeAsyncResult)result.AsyncState;
-                    thisPtr._connection.EndInitializeConnection(result);
-                    if (NetEventSource.IsEnabled) NetEventSource.Info(null, $"Connect returned {thisPtr}");
-
                     try
                     {
+                        thisPtr._connection.EndInitializeConnection(result);
+                        if (NetEventSource.IsEnabled) NetEventSource.Info(null, $"Connect returned {thisPtr}");
+
                         thisPtr.Handshake();
                     }
                     catch (Exception e)

diff --git a/src/System.Net.Mail/tests/Functional/SmtpClientTest.cs b/src/System.Net.Mail/tests/Functional/SmtpClientTest.cs
@@ -270,6 +270,24 @@ public void TestTimeout(int value)
             Assert.Equal(value, Smtp.Timeout);
         }
 
+        [Fact]
+        public void Send_ServerDoesntExist_Throws()
+        {
+            using (var smtp = new SmtpClient(Guid.NewGuid().ToString("N")))
+            {
+                Assert.Throws<SmtpException>(() => smtp.Send("[email protected]", "[email protected]", "subject", "body"));
+            }
+        }
+
+        [Fact]
+        public async Task SendAsync_ServerDoesntExist_Throws()
+        {
+            using (var smtp = new SmtpClient(Guid.NewGuid().ToString("N")))
+            {
+                await Assert.ThrowsAsync<SmtpException>(() => smtp.SendMailAsync("[email protected]", "[email protected]", "subject", "body"));
+            }
+        }
+
         [Fact]
         public void TestMailDelivery()
         {