CSHARP-6214: Implement srvAllowedHostsSuffix URI option

specifications/connection-string/tests/invalid-uris.json

@@ -252,6 +252,15 @@
       "auth": null,
       "options": null
     },
+    {
+      "description": "srvAllowedHostsSuffix with non-SRV URI",
+      "uri": "mongodb://localhost:27017/?srvAllowedHostsSuffix=.mongodb.net",
+      "valid": false,
+      "warning": null,
+      "hosts": null,
+      "auth": null,
+      "options": null
+    },
     {
       "description": "Username with password containing an unescaped percent sign",
       "uri": "mongodb://alice%foo:bar@127.0.0.1",

specifications/connection-string/tests/invalid-uris.yml

@@ -223,6 +223,14 @@ tests:
         hosts: ~
         auth: ~
         options: ~
+    -
+        description: "srvAllowedHostsSuffix with non-SRV URI"
+        uri: "mongodb://localhost:27017/?srvAllowedHostsSuffix=.mongodb.net"
+        valid: false
+        warning: ~
+        hosts: ~
+        auth: ~
+        options: ~
     -
         description: "Username with password containing an unescaped percent sign"
         uri: "mongodb://alice%foo:bar@127.0.0.1"

specifications/initial-dns-seedlist-discovery/tests/replica-set/srvAllowedHostsSuffix-case-insensitive.json

@@ -0,0 +1,10 @@
+{
+  "uri": "mongodb+srv://test12.test.build.10gen.cc/?srvAllowedHostsSuffix=.BUILD.10GEN.CC",
+  "seeds": [
+    "localhost.build.10gen.cc:27017"
+  ],
+  "options": {
+    "ssl": true
+  },
+  "ping": false
+}

specifications/initial-dns-seedlist-discovery/tests/replica-set/srvAllowedHostsSuffix-case-insensitive.yml

@@ -0,0 +1,8 @@
+# Tests that srvAllowedHostsSuffix comparison is case-insensitive (ASCII case folding per RFC 4343).
+# The suffix .BUILD.10GEN.CC is uppercase but should match the returned host localhost.build.10gen.cc.
+uri: "mongodb+srv://test12.test.build.10gen.cc/?srvAllowedHostsSuffix=.BUILD.10GEN.CC"
+seeds:
+    - localhost.build.10gen.cc:27017
+options:
+    ssl: true
+ping: false

specifications/initial-dns-seedlist-discovery/tests/replica-set/srvAllowedHostsSuffix-mismatch.json

@@ -0,0 +1,6 @@
+{
+  "uri": "mongodb+srv://test12.test.build.10gen.cc/?srvAllowedHostsSuffix=test.build.10gen.cc",
+  "seeds": [],
+  "hosts": [],
+  "error": true
+}

specifications/initial-dns-seedlist-discovery/tests/replica-set/srvAllowedHostsSuffix-mismatch.yml

@@ -0,0 +1,5 @@
+# DNS record for test12.test.build.10gen.cc returns localhost.build.10gen.cc which would not match test.build.10gen.cc
+uri: "mongodb+srv://test12.test.build.10gen.cc/?srvAllowedHostsSuffix=test.build.10gen.cc"
+seeds: []
+hosts: []
+error: true

specifications/initial-dns-seedlist-discovery/tests/replica-set/srvAllowedHostsSuffix-period-only.json

@@ -0,0 +1,6 @@
+{
+  "uri": "mongodb+srv://test1.test.build.10gen.cc/?srvAllowedHostsSuffix=.",
+  "seeds": [],
+  "hosts": [],
+  "error": true
+}

specifications/initial-dns-seedlist-discovery/tests/replica-set/srvAllowedHostsSuffix-period-only.yml

@@ -0,0 +1,7 @@
+# srvAllowedHostsSuffix MUST name at least one label. A value of "." is empty once the
+# leading and trailing "." are stripped, so it names no domain at all and MUST raise an
+# error rather than being treated as a suffix that every host matches.
+uri: "mongodb+srv://test1.test.build.10gen.cc/?srvAllowedHostsSuffix=."
+seeds: []
+hosts: []
+error: true

specifications/initial-dns-seedlist-discovery/tests/replica-set/srvAllowedHostsSuffix-tld-only.json

@@ -0,0 +1,6 @@
+{
+  "uri": "mongodb+srv://test1.test.build.10gen.cc/?srvAllowedHostsSuffix=.cc",
+  "seeds": [],
+  "hosts": [],
+  "error": true
+}

specifications/initial-dns-seedlist-discovery/tests/replica-set/srvAllowedHostsSuffix-tld-only.yml

@@ -0,0 +1,6 @@
+# srvAllowedHostsSuffix SHOULD NOT be a public suffix. "cc" is an ordinary rule in the
+# Public Suffix List, and isn't two or more `.` separated labels so `.cc` MUST raise an error.
+uri: "mongodb+srv://test1.test.build.10gen.cc/?srvAllowedHostsSuffix=.cc"
+seeds: []
+hosts: []
+error: true

specifications/initial-dns-seedlist-discovery/tests/replica-set/srvAllowedHostsSuffix-trailing-dot.json

@@ -0,0 +1,10 @@
+{
+  "uri": "mongodb+srv://test12.test.build.10gen.cc/?srvAllowedHostsSuffix=.build.10gen.cc.",
+  "seeds": [
+    "localhost.build.10gen.cc:27017"
+  ],
+  "options": {
+    "ssl": true
+  },
+  "ping": false
+}

specifications/initial-dns-seedlist-discovery/tests/replica-set/srvAllowedHostsSuffix-trailing-dot.yml

@@ -0,0 +1,8 @@
+# A trailing dot in srvAllowedHostsSuffix must be stripped before comparison,
+# so ".build.10gen.cc." is equivalent to ".build.10gen.cc".
+uri: "mongodb+srv://test12.test.build.10gen.cc/?srvAllowedHostsSuffix=.build.10gen.cc."
+seeds:
+    - localhost.build.10gen.cc:27017
+options:
+    ssl: true
+ping: false

specifications/initial-dns-seedlist-discovery/tests/replica-set/srvAllowedHostsSuffix-with_dot.json

@@ -0,0 +1,10 @@
+{
+  "uri": "mongodb+srv://test12.test.build.10gen.cc/?srvAllowedHostsSuffix=.build.10gen.cc",
+  "seeds": [
+    "localhost.build.10gen.cc:27017"
+  ],
+  "options": {
+    "ssl": true
+  },
+  "ping": false
+}

specifications/initial-dns-seedlist-discovery/tests/replica-set/srvAllowedHostsSuffix-with_dot.yml

@@ -0,0 +1,8 @@
+# Also tests trailing dot normalization: DNS returns targets with a trailing dot
+# (localhost.build.10gen.cc.) which must be stripped before suffix comparison.
+uri: "mongodb+srv://test12.test.build.10gen.cc/?srvAllowedHostsSuffix=.build.10gen.cc"
+seeds:
+    - localhost.build.10gen.cc:27017
+options:
+    ssl: true
+ping: false

specifications/initial-dns-seedlist-discovery/tests/replica-set/srvAllowedHostsSuffix-without_dot_fail.json

@@ -0,0 +1,6 @@
+{
+  "uri": "mongodb+srv://test12.test.build.10gen.cc/?srvAllowedHostsSuffix=uild.10gen.cc",
+  "seeds": [],
+  "hosts": [],
+  "error": true
+}

specifications/initial-dns-seedlist-discovery/tests/replica-set/srvAllowedHostsSuffix-without_dot_fail.yml

@@ -0,0 +1,5 @@
+# dot should be prepended to `srvAllowedHostsSuffix` causing the host to be .uild.10gen.cc which does not match any available DNS records
+uri: "mongodb+srv://test12.test.build.10gen.cc/?srvAllowedHostsSuffix=uild.10gen.cc"
+seeds: []
+hosts: []
+error: true

specifications/initial-dns-seedlist-discovery/tests/replica-set/srvAllowedHostsSuffix-without_dot_pass.json

@@ -0,0 +1,10 @@
+{
+  "uri": "mongodb+srv://test12.test.build.10gen.cc/?srvAllowedHostsSuffix=build.10gen.cc",
+  "seeds": [
+    "localhost.build.10gen.cc:27017"
+  ],
+  "options": {
+    "ssl": true
+  },
+  "ping": false
+}

specifications/initial-dns-seedlist-discovery/tests/replica-set/srvAllowedHostsSuffix-without_dot_pass.yml

@@ -0,0 +1,6 @@
+uri: "mongodb+srv://test12.test.build.10gen.cc/?srvAllowedHostsSuffix=build.10gen.cc"
+seeds:
+  - localhost.build.10gen.cc:27017
+options:
+  ssl: true
+ping: false

src/MongoDB.Driver/ClusterKey.cs

@@ -57,6 +57,7 @@ internal sealed class ClusterKey
         private readonly TimeSpan _serverSelectionTimeout;
         private readonly TimeSpan _socketTimeout;
         private readonly Socks5ProxySettings _socks5ProxySettings;
+        private readonly string _srvAllowedHostsSuffix;
         private readonly int _srvMaxHosts;
         private readonly string _srvServiceName;
         private readonly SslSettings _sslSettings;
@@ -97,6 +98,7 @@ public ClusterKey(
             TimeSpan serverSelectionTimeout,
             TimeSpan socketTimeout,
             Socks5ProxySettings socks5ProxySettings,
+            string srvAllowedHostsSuffix,
             int srvMaxHosts,
             string srvServiceName,
             SslSettings sslSettings,
@@ -135,6 +137,7 @@ public ClusterKey(
             _serverSelectionTimeout = serverSelectionTimeout;
             _socketTimeout = socketTimeout;
             _socks5ProxySettings = socks5ProxySettings;
+            _srvAllowedHostsSuffix = srvAllowedHostsSuffix;
             _srvMaxHosts = srvMaxHosts;
             _srvServiceName = srvServiceName;
             _sslSettings = sslSettings;
@@ -177,6 +180,7 @@ public ClusterKey(
         public TimeSpan ServerSelectionTimeout { get { return _serverSelectionTimeout; } }
         public TimeSpan SocketTimeout { get { return _socketTimeout; } }
         public Socks5ProxySettings Socks5ProxySettings { get { return _socks5ProxySettings; } }
+        public string SrvAllowedHostsSuffix { get { return _srvAllowedHostsSuffix; } }
         public int SrvMaxHosts { get { return _srvMaxHosts; } }
         public string SrvServiceName { get { return _srvServiceName; } }
         public SslSettings SslSettings { get { return _sslSettings; } }
@@ -234,6 +238,7 @@ public override bool Equals(object obj)
                 _serverSelectionTimeout == rhs._serverSelectionTimeout &&
                 _socketTimeout == rhs._socketTimeout &&
                 object.Equals(_socks5ProxySettings, rhs._socks5ProxySettings) &&
+                _srvAllowedHostsSuffix == rhs._srvAllowedHostsSuffix &&
                 _srvMaxHosts == rhs._srvMaxHosts &&
                 _srvServiceName == rhs.SrvServiceName &&
                 object.Equals(_sslSettings, rhs._sslSettings) &&

src/MongoDB.Driver/ClusterRegistry.cs

@@ -98,7 +98,8 @@ private ClusterSettings ConfigureCluster(ClusterSettings settings, ClusterKey cl
                 maxServerSelectionWaitQueueSize: clusterKey.WaitQueueSize,
                 serverApi: clusterKey.ServerApi,
                 serverSelectionTimeout: clusterKey.ServerSelectionTimeout,
-                scheme: clusterKey.Scheme);
+                scheme: clusterKey.Scheme)
+                .WithSrvAllowedHostsSuffix(clusterKey.SrvAllowedHostsSuffix);
         }
 
         private ConnectionPoolSettings ConfigureConnectionPool(ConnectionPoolSettings settings, ClusterKey clusterKey)

src/MongoDB.Driver/Core/Clusters/DnsMonitor.cs

@@ -28,22 +28,14 @@ namespace MongoDB.Driver.Core.Clusters
 {
     internal class DnsMonitor : IDnsMonitor
     {
-        #region static
-        private static string EnsureLookupDomainNameIsValid(string lookupDomainName)
-        {
-            Ensure.IsNotNull(lookupDomainName, nameof(lookupDomainName));
-            Ensure.That(lookupDomainName.Count(c => c == '.') >= 2, "LookupDomainName must have at least three components.", nameof(lookupDomainName));
-            return lookupDomainName;
-        }
-        #endregion
-
         // private fields
         private readonly CancellationToken _cancellationToken;
         private readonly IDnsMonitoringCluster _cluster;
         private readonly IDnsResolver _dnsResolver;
         private readonly string _lookupDomainName;
         private bool _processDnsResultHasEverBeenCalled;
         private readonly string _service;
+        private readonly string _srvParentDomain;
         private DnsMonitorState _state;
         private Exception _unhandledException;
 
@@ -54,15 +46,28 @@ public DnsMonitor(IDnsMonitoringCluster cluster,
             IDnsResolver dnsResolver,
             string srvServiceName,
             string lookupDomainName,
+            string srvAllowedHostsSuffix,
             IEventSubscriber eventSubscriber,
             ILogger<LogCategories.SDAM> logger,
             CancellationToken cancellationToken)
         {
             _cluster = Ensure.IsNotNull(cluster, nameof(cluster));
             _dnsResolver = Ensure.IsNotNull(dnsResolver, nameof(dnsResolver));
-            _lookupDomainName = EnsureLookupDomainNameIsValid(lookupDomainName);
+            Ensure.IsNotNullOrEmpty(lookupDomainName, nameof(lookupDomainName));
+
+            // the domain that resolved hosts are validated against carries the same normalization
+            // the hosts themselves do. The query name is built from the normalized form as well,
+            // since DNS is case insensitive and expects A-labels on the wire.
+            if (!ConnectionString.TryNormalizeHostName(lookupDomainName, out _lookupDomainName))
+            {
+                throw new MongoConfigurationException($"Unable to parse {lookupDomainName} as a hostname.");
+            }
+
             _cancellationToken = cancellationToken;
             _service = $"_{srvServiceName}._tcp." + _lookupDomainName;
+            _srvParentDomain = srvAllowedHostsSuffix == null
+                ? null
+                : ConnectionString.NormalizeSrvAllowedHostsSuffix(srvAllowedHostsSuffix);
             _state = DnsMonitorState.Created;
 
             _eventLogger = logger.ToEventLogger(eventSubscriber);
@@ -133,14 +138,15 @@ private List<DnsEndPoint> GetValidEndPoints(List<SrvRecord> srvRecords)
 
             foreach (var srvRecord in srvRecords)
             {
+                var endPoint = srvRecord.EndPoint;
                 // DNS names are case-insensitive, and SDAM requires host names to be normalized to lower-case
-                var host = srvRecord.EndPoint.Host.ToLowerInvariant();
-                if (host.EndsWith(".", StringComparison.Ordinal))
+                if (!ConnectionString.TryNormalizeHostName(endPoint.Host, out var host))
                 {
-                    host = host.Substring(0, host.Length - 1);
+                    _eventLogger.LogAndPublish(new SdamInformationEvent("Unable to parse host returned by DNS SRV lookup: {0}.", endPoint.Host));
+                    continue;
                 }
 
-                var endPoint = new DnsEndPoint(host, srvRecord.EndPoint.Port);
+                endPoint = new DnsEndPoint(host, endPoint.Port);
                 if (IsValidHost(endPoint))
                 {
                     validEndPoints.Add(endPoint);
@@ -156,7 +162,7 @@ private List<DnsEndPoint> GetValidEndPoints(List<SrvRecord> srvRecords)
 
         private bool IsValidHost(DnsEndPoint endPoint)
         {
-            return ConnectionString.HasValidParentDomain(_lookupDomainName, endPoint);
+            return ConnectionString.HasValidParentDomain(_lookupDomainName, endPoint, _srvParentDomain);
         }
 
         private void Monitor()

src/MongoDB.Driver/Core/Clusters/DnsMonitorFactory.cs

@@ -32,10 +32,10 @@ public DnsMonitorFactory(IEventSubscriber eventSubscriber, ILoggerFactory logger
             _loggerFactory = loggerFactory;
         }
 
-        public IDnsMonitor CreateDnsMonitor(IDnsMonitoringCluster cluster, string srvServiceName, string lookupDomainName, CancellationToken cancellationToken)
+        public IDnsMonitor CreateDnsMonitor(IDnsMonitoringCluster cluster, string srvServiceName, string lookupDomainName, string srvAllowedHostsSuffix, CancellationToken cancellationToken)
         {
             var dnsResolver = DnsClientWrapper.Instance;
-            return new DnsMonitor(cluster, dnsResolver, srvServiceName, lookupDomainName, _eventSubscriber, _loggerFactory?.CreateLogger<LogCategories.SDAM>(), cancellationToken);
+            return new DnsMonitor(cluster, dnsResolver, srvServiceName, lookupDomainName, srvAllowedHostsSuffix, _eventSubscriber, _loggerFactory?.CreateLogger<LogCategories.SDAM>(), cancellationToken);
         }
     }
 }

src/MongoDB.Driver/Core/Clusters/IDnsMonitorFactory.cs

@@ -19,6 +19,6 @@ namespace MongoDB.Driver.Core.Clusters
 {
     internal interface IDnsMonitorFactory
     {
-        IDnsMonitor CreateDnsMonitor(IDnsMonitoringCluster cluster, string srvServiceName, string lookupDomainName, CancellationToken cancellationToken);
+        IDnsMonitor CreateDnsMonitor(IDnsMonitoringCluster cluster, string srvServiceName, string lookupDomainName, string srvAllowedHostsSuffix, CancellationToken cancellationToken);
     }
 }

src/MongoDB.Driver/Core/Clusters/LoadBalancedCluster.cs

@@ -188,7 +188,7 @@ public void Initialize()
                     // _server will be created after srv resolving
                     var dnsEndPoint = (DnsEndPoint)endPoint;
                     var lookupDomainName = dnsEndPoint.Host;
-                    var monitor = _dnsMonitorFactory.CreateDnsMonitor(this, _settings.SrvServiceName, lookupDomainName, _dnsMonitorCancellationTokenSource.Token);
+                    var monitor = _dnsMonitorFactory.CreateDnsMonitor(this, _settings.SrvServiceName, lookupDomainName, _settings.SrvAllowedHostsSuffix, _dnsMonitorCancellationTokenSource.Token);
                     _dnsMonitorThread = monitor.Start();
                 }
 

src/MongoDB.Driver/Core/Clusters/MultiServerCluster.cs

@@ -141,7 +141,7 @@ public override void Initialize()
                 {
                     var dnsEndPoint = (DnsEndPoint)Settings.EndPoints.Single();
                     var lookupDomainName = dnsEndPoint.Host;
-                    var dnsMonitor = _dnsMonitorFactory.CreateDnsMonitor(this, Settings.SrvServiceName, lookupDomainName, _monitorServersCancellationTokenSource.Token);
+                    var dnsMonitor = _dnsMonitorFactory.CreateDnsMonitor(this, Settings.SrvServiceName, lookupDomainName, Settings.SrvAllowedHostsSuffix, _monitorServersCancellationTokenSource.Token);
                     _dnsMonitorThread = dnsMonitor.Start(); // store the Thread for use as evidence when testing that the DnsMonitor was started
                 }
             }