enable forcing client auth

src/csharp/Grpc.Core/Internal/ServerCredentialsSafeHandle.cs

@@ -42,7 +42,7 @@ namespace Grpc.Core.Internal
     internal class ServerCredentialsSafeHandle : SafeHandleZeroIsInvalid
     {
         [DllImport("grpc_csharp_ext.dll", CharSet = CharSet.Ansi)]
-        static extern ServerCredentialsSafeHandle grpcsharp_ssl_server_credentials_create(string pemRootCerts, string[] keyCertPairCertChainArray, string[] keyCertPairPrivateKeyArray, UIntPtr numKeyCertPairs);
+        static extern ServerCredentialsSafeHandle grpcsharp_ssl_server_credentials_create(string pemRootCerts, string[] keyCertPairCertChainArray, string[] keyCertPairPrivateKeyArray, UIntPtr numKeyCertPairs, bool forceClientAuth);
 
         [DllImport("grpc_csharp_ext.dll")]
         static extern void grpcsharp_server_credentials_release(IntPtr credentials);
@@ -51,12 +51,13 @@ namespace Grpc.Core.Internal
         {
         }
 
-        public static ServerCredentialsSafeHandle CreateSslCredentials(string pemRootCerts, string[] keyCertPairCertChainArray, string[] keyCertPairPrivateKeyArray)
+        public static ServerCredentialsSafeHandle CreateSslCredentials(string pemRootCerts, string[] keyCertPairCertChainArray, string[] keyCertPairPrivateKeyArray, bool forceClientAuth)
         {
             Preconditions.CheckArgument(keyCertPairCertChainArray.Length == keyCertPairPrivateKeyArray.Length);
             return grpcsharp_ssl_server_credentials_create(pemRootCerts,
                                                            keyCertPairCertChainArray, keyCertPairPrivateKeyArray,
-                                                           new UIntPtr((ulong)keyCertPairCertChainArray.Length));
+                                                           new UIntPtr((ulong)keyCertPairCertChainArray.Length),
+                                                           forceClientAuth);
         }
 
         protected override bool ReleaseHandle()

src/csharp/Grpc.Core/ServerCredentials.cs

@@ -80,18 +80,26 @@ namespace Grpc.Core
     {
         readonly IList<KeyCertificatePair> keyCertificatePairs;
         readonly string rootCertificates;
+        readonly bool forceClientAuth;
 
         /// <summary>
         /// Creates server-side SSL credentials.
         /// </summary>
-        /// <param name="rootCertificates">PEM encoded client root certificates used to authenticate client.</param>
         /// <param name="keyCertificatePairs">Key-certificates to use.</param>
-        public SslServerCredentials(IEnumerable<KeyCertificatePair> keyCertificatePairs, string rootCertificates)
+        /// <param name="rootCertificates">PEM encoded client root certificates used to authenticate client.</param>
+        /// <param name="forceClientAuth">If true, client will be rejected unless it proves its unthenticity using against rootCertificates.</param>
+        public SslServerCredentials(IEnumerable<KeyCertificatePair> keyCertificatePairs, string rootCertificates, bool forceClientAuth)
         {
             this.keyCertificatePairs = new List<KeyCertificatePair>(keyCertificatePairs).AsReadOnly();
             Preconditions.CheckArgument(this.keyCertificatePairs.Count > 0,
                 "At least one KeyCertificatePair needs to be provided");
+            if (forceClientAuth)
+            {
+                Preconditions.CheckNotNull(rootCertificates,
+                    "Cannot force client authentication unless you provide rootCertificates.");
+            }
             this.rootCertificates = rootCertificates;
+            this.forceClientAuth = forceClientAuth;
         }
 
         /// <summary>
@@ -100,7 +108,7 @@ namespace Grpc.Core
         /// using client root certificates.
         /// </summary>
         /// <param name="keyCertificatePairs">Key-certificates to use.</param>
-        public SslServerCredentials(IEnumerable<KeyCertificatePair> keyCertificatePairs) : this(keyCertificatePairs, null)
+        public SslServerCredentials(IEnumerable<KeyCertificatePair> keyCertificatePairs) : this(keyCertificatePairs, null, false)
         {
         }
 
@@ -126,6 +134,17 @@ namespace Grpc.Core
             }
         }
 
+        /// <summary>
+        /// If true, the authenticity of client check will be enforced.
+        /// </summary>
+        public bool ForceClientAuthentication
+        {
+            get
+            {
+                return this.forceClientAuth;
+            }
+        }
+
         internal override ServerCredentialsSafeHandle ToNativeCredentials()
         {
             int count = keyCertificatePairs.Count;
@@ -136,7 +155,7 @@ namespace Grpc.Core
                 certChains[i] = keyCertificatePairs[i].CertificateChain;
                 keys[i] = keyCertificatePairs[i].PrivateKey;
             }
-            return ServerCredentialsSafeHandle.CreateSslCredentials(rootCertificates, certChains, keys);
+            return ServerCredentialsSafeHandle.CreateSslCredentials(rootCertificates, certChains, keys, forceClientAuth);
         }
     }
 }

src/csharp/Grpc.IntegrationTesting/SslCredentialsTest.cs

@@ -62,7 +62,7 @@ namespace Grpc.IntegrationTesting
                 File.ReadAllText(TestCredentials.ServerCertChainPath),
                 File.ReadAllText(TestCredentials.ServerPrivateKeyPath));
 
-            var serverCredentials = new SslServerCredentials(new[] { keyCertPair }, rootCert);
+            var serverCredentials = new SslServerCredentials(new[] { keyCertPair }, rootCert, true);
             var clientCredentials = new SslCredentials(rootCert, keyCertPair);
 
             server = new Server();

src/csharp/ext/grpc_csharp_ext.c

@@ -792,7 +792,8 @@ grpcsharp_secure_channel_create(grpc_credentials *creds, const char *target,
 GPR_EXPORT grpc_server_credentials *GPR_CALLTYPE
 grpcsharp_ssl_server_credentials_create(
     const char *pem_root_certs, const char **key_cert_pair_cert_chain_array,
-    const char **key_cert_pair_private_key_array, size_t num_key_cert_pairs) {
+    const char **key_cert_pair_private_key_array, size_t num_key_cert_pairs,
+    int force_client_auth) {
   size_t i;
   grpc_server_credentials *creds;
   grpc_ssl_pem_key_cert_pair *key_cert_pairs =
@@ -807,9 +808,9 @@ grpcsharp_ssl_server_credentials_create(
       key_cert_pairs[i].private_key = key_cert_pair_private_key_array[i];
     }
   }
-  /* TODO: Add a force_client_auth parameter and pass it here. */
   creds = grpc_ssl_server_credentials_create(pem_root_certs, key_cert_pairs,
-                                             num_key_cert_pairs, 0);
+                                             num_key_cert_pairs,
+                                             force_client_auth);
   gpr_free(key_cert_pairs);
   return creds;
 }