Exception on passing different gateway hostnames through different in…

…puts (#3330)

iothub/device/src/Authentication/IotHubConnectionCredentials.cs

@@ -62,6 +62,8 @@ public IotHubConnectionCredentials(IAuthenticationMethod authenticationMethod, s
         /// <returns>A new instance of this class.</returns>
         /// <exception cref="ArgumentNullException"><paramref name="iotHubConnectionString"/>, IoT hub host name or device Id is null.</exception>
         /// <exception cref="ArgumentException"><paramref name="iotHubConnectionString"/>, IoT hub host name or device Id are an empty string or consist only of white-space characters.</exception>
+        /// <exception cref="InvalidOperationException">Different gateway hostnames were specified through the connection string and <see cref="IotHubClientOptions.GatewayHostName"/>.
+        /// It is recommended to use <see cref="IotHubClientOptions"/> to specify values for the additional fields rather than hand edit connection strings.</exception>
         /// <exception cref="FormatException">Neither shared access key nor shared access signature were presented for authentication.</exception>
         /// <exception cref="FormatException">Either shared access key or shared access signature where presented together with X509 certificates for authentication.</exception>
         public IotHubConnectionCredentials(string iotHubConnectionString, string gatewayHostName = default)
@@ -70,8 +72,18 @@ public IotHubConnectionCredentials(string iotHubConnectionString, string gateway
 
             // We'll parse the connection string and use that to build an auth method
             IotHubConnectionString parsedConnectionString = IotHubConnectionStringParser.Parse(iotHubConnectionString);
-            AuthenticationMethod = GetAuthenticationMethodFromConnectionString(parsedConnectionString);
 
+            // The gateway hostname shouldn't be specified in both the connection string and in IotHubClientOptions
+            // If they are specified in both places then they should always be equal (case-sensitive and culture-insensitive comparison).
+            if (!string.IsNullOrWhiteSpace(parsedConnectionString.GatewayHostName) && !string.IsNullOrWhiteSpace(gatewayHostName))
+            {
+                if (parsedConnectionString.GatewayHostName != gatewayHostName)
+                {
+                    throw new InvalidOperationException("Different gateway host names were supplied through the connection string and IotHubClientOptions. Please supply the gateway host name through one argument only.");
+                }
+            }
+
+            AuthenticationMethod = GetAuthenticationMethodFromConnectionString(parsedConnectionString);
             PopulatePropertiesFromConnectionString(parsedConnectionString, gatewayHostName);
             SetAuthenticationModel();
             SetTokenRefresherIfApplicable();

iothub/device/src/IotHubClientOptions.cs

@@ -85,10 +85,6 @@ public IotHubClientOptions(IotHubClientTransportSettings transportSettings)
         /// <para>
         /// It can also be used for other, custom transparent or protocol gateways.
         /// </para>
-        /// <para>
-        /// If the client uses a connection string-based authentication mechanism, and has a gateway hostname specified in the connection string
-        /// then the value set in options will be ignored.
-        /// </para>
         /// </remarks>
         public string GatewayHostName { get; set; }
 

iothub/device/src/IotHubDeviceClient.cs

@@ -29,6 +29,8 @@ public class IotHubDeviceClient : IotHubBaseClient
         /// or the IoT hub host name or device Id in the connection string are an empty string or consist only of white-space characters.</exception>
         /// <exception cref="ArgumentException">Neither shared access key nor shared access signature were presented for authentication.</exception>
         /// <exception cref="InvalidOperationException">A module Id was specified in the connection string. <see cref="IotHubModuleClient"/> should be used for modules.</exception>
+        /// <exception cref="InvalidOperationException">Different gateway hostnames were specified through the connection string and <see cref="IotHubClientOptions.GatewayHostName"/>.
+        /// It is recommended to use <see cref="IotHubClientOptions"/> to specify values for the additional fields rather than hand edit connection strings.</exception>
         /// <example>
         /// <code language="csharp">
         /// await using var client = new IotHubDeviceClient(

iothub/device/src/IotHubModuleClient.cs

@@ -40,6 +40,8 @@ public class IotHubModuleClient : IotHubBaseClient
         /// <exception cref="InvalidOperationException">Required key/value pairs were missing from the connection string.</exception>
         /// <returns>A disposable client instance.</returns>
         /// <exception cref="InvalidOperationException">A module Id was missing in the connection string. <see cref="IotHubDeviceClient"/> should be used for devices.</exception>
+        /// <exception cref="InvalidOperationException">Different gateway hostnames were specified through the connection string and <see cref="IotHubClientOptions.GatewayHostName"/>.
+        /// It is recommended to use <see cref="IotHubClientOptions"/> to specify values for the additional fields rather than hand edit connection strings.</exception>
         /// <example>
         /// <code language="csharp">
         /// await using var client = new IotHubModuleClient(

iothub/device/tests/IotHubDeviceClientTests.cs

@@ -1634,7 +1634,7 @@ private static void IotHubDeviceClient_InitWithNonHttpTransportAndModelId_DoesNo
         }
 
         [TestMethod]
-        public async Task IotHubDeviceClient_CreateFromConnectionString_WithoutWithGatewayHostname_UseIotHubClientOptionsGatewayHostName()
+        public async Task IotHubDeviceClient_CreateFromConnectionString_UseIotHubClientOptionsGatewayHostName()
         {
             // arrange
             var clientOptions = new IotHubClientOptions
@@ -1652,7 +1652,19 @@ public async Task IotHubDeviceClient_CreateFromConnectionString_WithoutWithGatew
         }
 
         [TestMethod]
-        public async Task IotHubDeviceClient_CreateFromConnectionString_WithGatewayHostname_OverrideIotHubClientOptionsGatewayHostName()
+        public async Task IotHubDeviceClient_CreateFromConnectionString__UseConnectionStringGatewayHostName()
+        {
+            // arrange and act
+            await using var deviceClient = new IotHubDeviceClient(s_fakeConnectionStringWithGatewayHostName);
+
+            // assert
+            deviceClient.IotHubConnectionCredentials.IotHubHostName.Should().Be(FakeHostName);
+            deviceClient.IotHubConnectionCredentials.GatewayHostName.Should().Be(FakeGatewayHostNameCs);
+            deviceClient.IotHubConnectionCredentials.HostName.Should().Be(FakeGatewayHostNameCs);
+        }
+
+        [TestMethod]
+        public void IotHubDeviceClient_CreateFromConnectionString_PassMultipleGatewayHostName_ThrowsException()
         {
             // arrange
             var clientOptions = new IotHubClientOptions
@@ -1661,12 +1673,10 @@ public async Task IotHubDeviceClient_CreateFromConnectionString_WithGatewayHostn
             };
 
             // act
-            await using var deviceClient = new IotHubDeviceClient(s_fakeConnectionStringWithGatewayHostName, clientOptions);
+            Func<IotHubDeviceClient> act = () => new IotHubDeviceClient(s_fakeConnectionStringWithGatewayHostName, clientOptions);
 
             // assert
-            deviceClient.IotHubConnectionCredentials.IotHubHostName.Should().Be(FakeHostName);
-            deviceClient.IotHubConnectionCredentials.GatewayHostName.Should().Be(FakeGatewayHostNameCs);
-            deviceClient.IotHubConnectionCredentials.HostName.Should().Be(FakeGatewayHostNameCs);
+            act.Should().Throw<InvalidOperationException>();
         }
 
         private class TestDeviceAuthenticationWithTokenRefresh : ClientAuthenticationWithTokenRefresh