Support srvServiceName option for SRV lookups (#843)

JAVA-4239

Author: jyemin

config/checkstyle/suppressions.xml

@@ -31,6 +31,7 @@
 
     <suppress checks="MethodLength" files="PojoRoundTripTest"/>
     <suppress checks="MethodLength" files="AbstractUnifiedTest"/>
+    <suppress checks="MethodLength" files="ConnectionString"/>
 
     <suppress checks="JavadocPackage" files="com[\\/]mongodb[\\/][^\\/]*\.java"/>
     <suppress checks="JavadocPackage" files="com[\\/]mongodb[\\/]client[\\/][^\\/]*\.java"/>

driver-core/src/main/com/mongodb/ConnectionString.java

@@ -16,6 +16,7 @@
 
 package com.mongodb;
 
+import com.mongodb.connection.ClusterSettings;
 import com.mongodb.connection.ConnectionPoolSettings;
 import com.mongodb.diagnostics.logging.Logger;
 import com.mongodb.diagnostics.logging.Loggers;
@@ -77,7 +78,8 @@
  * connecting to a database server.  For some authentication mechanisms, only the username is specified and the password is not,
  * in which case the ":" after the username is left off as well</li>
  * <li>{@code host} is the only required part of the URI.  It identifies a single host name for which SRV records are looked up
- * from a Domain Name Server after prefixing the host name with {@code "_mongodb._tcp"}.  The host/port for each SRV record becomes the
+ * from a Domain Name Server after prefixing the host name with, by default, {@code "_mongodb._tcp"} ({@code "mongodb"} is the default SRV
+ * service name, but can be replaced via the {@code srvServiceName} query parameter),  The host/port for each SRV record becomes the
  * seed list used to connect, as if each one were provided as host/port pair in a URI using the normal mongodb protocol.</li>
  * <li>{@code /database} is the name of the database to login to and thus is only relevant if the
  * {@code username:password@} syntax is used. If not specified the "admin" database will be used by default.</li>
@@ -220,6 +222,11 @@
  * <li>{@code zlibCompressionLevel=integer}: Integer value from -1 to 9 representing the zlib compression level. Lower values will make
  * compression faster, while higher values will make compression better.</li>
  * </ul>
+ * <p>SRV configuration:</p>
+ * <ul>
+ * <li>{@code srvServiceName=string}: The SRV service name. See {@link ClusterSettings#getSrvServiceName()} for details.</li>
+ * <li>{@code srvMaxHosts=number}: The maximum number of hosts from the SRV record to connect to.</li>
+ * </ul>
  * <p>General configuration:</p>
  * <ul>
  * <li>{@code retryWrites=true|false}. If true the driver will retry supported write operations if they fail due to a network error.
@@ -254,6 +261,7 @@ public class ConnectionString {
     private final String connectionString;
 
     private Integer srvMaxHosts;
+    private String srvServiceName;
     private Boolean directConnection;
     private Boolean loadBalanced;
     private ReadPreference readPreference;
@@ -404,6 +412,10 @@ public ConnectionString(final String connectionString) {
             throw new IllegalArgumentException("srvMaxHosts can only be specified with mongodb+srv protocol");
         }
 
+        if (!isSrvProtocol && srvServiceName != null) {
+            throw new IllegalArgumentException("srvServiceName can only be specified with mongodb+srv protocol");
+        }
+
         if (directConnection != null && directConnection) {
             if (isSrvProtocol) {
                 throw new IllegalArgumentException("Direct connections are not supported when using mongodb+srv protocol");
@@ -482,6 +494,7 @@ public ConnectionString(final String connectionString) {
         GENERAL_OPTIONS_KEYS.add("loadbalanced");
 
         GENERAL_OPTIONS_KEYS.add("srvmaxhosts");
+        GENERAL_OPTIONS_KEYS.add("srvservicename");
 
         COMPRESSOR_KEYS.add("compressors");
         COMPRESSOR_KEYS.add("zlibcompressionlevel");
@@ -594,6 +607,8 @@ private void translateOptions(final Map<String, List<String>> optionsMap) {
                 if (srvMaxHosts < 0) {
                     throw new IllegalArgumentException("srvMaxHosts must be >= 0");
                 }
+            } else if (key.equals("srvservicename")) {
+                srvServiceName = value;
             }
         }
 
@@ -1134,6 +1149,19 @@ public Integer getSrvMaxHosts() {
         return srvMaxHosts;
     }
 
+    /**
+     * Gets the SRV service name.
+     *
+     * @return the SRV service name.  Defaults to null in the connection string, but defaults to {@code "mongodb"} in
+     * {@link ClusterSettings}.
+     * @since 4.5
+     * @see ClusterSettings#getSrvServiceName()
+     */
+    @Nullable
+    public String getSrvServiceName() {
+        return srvServiceName;
+    }
+
     /**
      * Gets the list of hosts
      *
@@ -1474,7 +1502,9 @@ public boolean equals(final Object o) {
                 && Objects.equals(heartbeatFrequency, that.heartbeatFrequency)
                 && Objects.equals(applicationName, that.applicationName)
                 && Objects.equals(compressorList, that.compressorList)
-                && Objects.equals(uuidRepresentation, that.uuidRepresentation);
+                && Objects.equals(uuidRepresentation, that.uuidRepresentation)
+                && Objects.equals(srvServiceName, that.srvServiceName)
+                && Objects.equals(srvMaxHosts, that.srvMaxHosts);
     }
 
     @Override
@@ -1483,6 +1513,6 @@ public int hashCode() {
                 writeConcern, retryWrites, retryReads, readConcern, minConnectionPoolSize, maxConnectionPoolSize, maxWaitTime,
                 maxConnectionIdleTime, maxConnectionLifeTime, maxConnecting, connectTimeout, socketTimeout, sslEnabled,
                 sslInvalidHostnameAllowed, requiredReplicaSetName, serverSelectionTimeout, localThreshold, heartbeatFrequency,
-                applicationName, compressorList, uuidRepresentation);
+                applicationName, compressorList, uuidRepresentation, srvServiceName, srvMaxHosts);
     }
 }

driver-core/src/main/com/mongodb/connection/ClusterSettings.java

@@ -28,6 +28,7 @@
 import java.util.ArrayList;
 import java.util.LinkedHashSet;
 import java.util.List;
+import java.util.Objects;
 import java.util.Set;
 import java.util.concurrent.TimeUnit;
 import java.util.stream.Collectors;
@@ -49,6 +50,7 @@
 public final class ClusterSettings {
     private final String srvHost;
     private final Integer srvMaxHosts;
+    private final String srvServiceName;
     private final List<ServerAddress> hosts;
     private final ClusterConnectionMode mode;
     private final ClusterType requiredClusterType;
@@ -86,6 +88,7 @@ public static final class Builder {
         private static final List<ServerAddress> DEFAULT_HOSTS = singletonList(new ServerAddress());
         private String srvHost;
         private Integer srvMaxHosts;
+        private String srvServiceName = "mongodb";
         private List<ServerAddress> hosts = DEFAULT_HOSTS;
         private ClusterConnectionMode mode;
         private ClusterType requiredClusterType = ClusterType.UNKNOWN;
@@ -110,6 +113,8 @@ private Builder() {
         public Builder applySettings(final ClusterSettings clusterSettings) {
             notNull("clusterSettings", clusterSettings);
             srvHost = clusterSettings.srvHost;
+            srvServiceName = clusterSettings.srvServiceName;
+            srvMaxHosts = clusterSettings.srvMaxHosts;
             hosts = clusterSettings.hosts;
             mode = clusterSettings.mode;
             requiredReplicaSetName = clusterSettings.requiredReplicaSetName;
@@ -156,6 +161,28 @@ public Builder srvMaxHosts(final Integer srvMaxHosts) {
             return this;
         }
 
+        /**
+         * Sets the SRV service name.
+         *
+         * <p>
+         * The SRV resource record (<a href="https://www.rfc-editor.org/rfc/rfc2782">RFC 2782</a>)
+         * service name, which is limited to 15 characters
+         * (<a href="https://www.rfc-editor.org/rfc/rfc6335#section-5.1">RFC 6335 section 5.1</a>).
+         * If specified, it is combined with the single host name specified by
+         * {@link #getHosts()} as follows: {@code _srvServiceName._tcp.hostName}. The combined string is an SRV resource record
+         * name (<a href="https://www.rfc-editor.org/rfc/rfc1035#section-2.3.1">RFC 1035 section 2.3.1</a>), which is limited to 255
+         * characters (<a href="https://www.rfc-editor.org/rfc/rfc1035#section-2.3.4">RFC 1035 section 2.3.4</a>).
+         * </p>
+         *
+         * @param srvServiceName the SRV service name
+         * @return this
+         * @since 4.5
+        */
+        public Builder srvServiceName(final String srvServiceName) {
+            this.srvServiceName = notNull("srvServiceName", srvServiceName);
+            return this;
+        }
+
         /**
          * Sets the hosts for the cluster. Any duplicate server addresses are removed from the list.
          *
@@ -302,6 +329,9 @@ public Builder applyConnectionString(final ConnectionString connectionString) {
                 mode(ClusterConnectionMode.MULTIPLE);
                 srvHost(connectionString.getHosts().get(0));
                 srvMaxHosts(connectionString.getSrvMaxHosts());
+                if (connectionString.getSrvServiceName() != null) {
+                    srvServiceName(connectionString.getSrvServiceName());
+                }
             } else if ((directConnection != null && directConnection)
                     || (directConnection == null && connectionString.getHosts().size() == 1
                         && connectionString.getRequiredReplicaSetName() == null)) {
@@ -358,6 +388,26 @@ public Integer getSrvMaxHosts() {
         return srvMaxHosts;
     }
 
+     /**
+      * Gets the SRV service name.
+      *
+      * <p>
+      * The SRV resource record (<a href="https://www.rfc-editor.org/rfc/rfc2782">RFC 2782</a>)
+      * service name, which is limited to 15 characters
+      * (<a href="https://www.rfc-editor.org/rfc/rfc6335#section-5.1">RFC 6335 section 5.1</a>).
+      * If specified, it is combined with the single host name specified by
+      * {@link #getHosts()} as follows: {@code _srvServiceName._tcp.hostName}. The combined string is an SRV resource record
+      * name (<a href="https://www.rfc-editor.org/rfc/rfc1035#section-2.3.1">RFC 1035 section 2.3.1</a>), which is limited to 255
+      * characters (<a href="https://www.rfc-editor.org/rfc/rfc1035#section-2.3.4">RFC 1035 section 2.3.4</a>).
+      * </p>
+      *
+      * @return the SRV service name, which defaults to {@code "mongodb"}
+      * @since 4.5
+     */
+    public String getSrvServiceName() {
+        return srvServiceName;
+    }
+
     /**
      * Gets the seed list of hosts for the cluster.
      *
@@ -477,60 +527,33 @@ public boolean equals(final Object o) {
         if (o == null || getClass() != o.getClass()) {
             return false;
         }
-
         ClusterSettings that = (ClusterSettings) o;
-
-        if (serverSelectionTimeoutMS != that.serverSelectionTimeoutMS) {
-            return false;
-        }
-        if (localThresholdMS != that.localThresholdMS) {
-            return false;
-        }
-        if (srvHost != null ? !srvHost.equals(that.srvHost) : that.srvHost != null) {
-            return false;
-        }
-        if (!hosts.equals(that.hosts)) {
-            return false;
-        }
-        if (mode != that.mode) {
-            return false;
-        }
-        if (requiredClusterType != that.requiredClusterType) {
-            return false;
-        }
-        if (requiredReplicaSetName != null ? !requiredReplicaSetName.equals(that.requiredReplicaSetName)
-                    : that.requiredReplicaSetName != null) {
-            return false;
-        }
-        if (serverSelector != null ? !serverSelector.equals(that.serverSelector) : that.serverSelector != null) {
-            return false;
-        }
-        if (!clusterListeners.equals(that.clusterListeners)) {
-            return false;
-        }
-
-        return true;
+        return localThresholdMS == that.localThresholdMS
+                && serverSelectionTimeoutMS == that.serverSelectionTimeoutMS
+                && Objects.equals(srvHost, that.srvHost)
+                && Objects.equals(srvMaxHosts, that.srvMaxHosts)
+                && srvServiceName.equals(that.srvServiceName)
+                && hosts.equals(that.hosts)
+                && mode == that.mode
+                && requiredClusterType == that.requiredClusterType
+                && Objects.equals(requiredReplicaSetName, that.requiredReplicaSetName)
+                && Objects.equals(serverSelector, that.serverSelector)
+                && clusterListeners.equals(that.clusterListeners);
     }
 
     @Override
     public int hashCode() {
-        int result = hosts.hashCode();
-        result = 31 * result + (srvHost != null ? srvHost.hashCode() : 0);
-        result = 31 * result + mode.hashCode();
-        result = 31 * result + requiredClusterType.hashCode();
-        result = 31 * result + (requiredReplicaSetName != null ? requiredReplicaSetName.hashCode() : 0);
-        result = 31 * result + (serverSelector != null ? serverSelector.hashCode() : 0);
-        result = 31 * result + (int) (serverSelectionTimeoutMS ^ (serverSelectionTimeoutMS >>> 32));
-        result = 31 * result + (int) (localThresholdMS ^ (localThresholdMS >>> 32));
-        result = 31 * result + clusterListeners.hashCode();
-        return result;
+        return Objects.hash(srvHost, srvMaxHosts, srvServiceName, hosts, mode, requiredClusterType, requiredReplicaSetName, serverSelector,
+                localThresholdMS, serverSelectionTimeoutMS, clusterListeners);
     }
 
     @Override
     public String toString() {
         return "{"
                + (hosts.isEmpty() ? "" : "hosts=" + hosts)
                + (srvHost == null ? "" : ", srvHost=" + srvHost)
+               + (srvServiceName == null ? "" : ", srvServiceName=" + srvServiceName)
+               + (srvMaxHosts == null ? "" : ", srvMaxHosts=" + srvMaxHosts)
                + ", mode=" + mode
                + ", requiredClusterType=" + requiredClusterType
                + ", requiredReplicaSetName='" + requiredReplicaSetName + '\''
@@ -588,6 +611,7 @@ private ClusterSettings(final Builder builder) {
 
         srvHost = builder.srvHost;
         srvMaxHosts = builder.srvMaxHosts;
+        srvServiceName = builder.srvServiceName;
         hosts = builder.hosts;
         if (srvHost != null) {
             if (builder.mode == ClusterConnectionMode.SINGLE) {

driver-core/src/main/com/mongodb/internal/connection/DefaultDnsSrvRecordMonitor.java

@@ -37,17 +37,19 @@ class DefaultDnsSrvRecordMonitor implements DnsSrvRecordMonitor {
     private static final Logger LOGGER = Loggers.getLogger("cluster");
 
     private final String hostName;
+    private final String srvServiceName;
     private final long rescanFrequencyMillis;
     private final long noRecordsRescanFrequencyMillis;
     private final DnsSrvRecordInitializer dnsSrvRecordInitializer;
     private final DnsResolver dnsResolver;
     private final Thread monitorThread;
     private volatile boolean isClosed;
 
-    DefaultDnsSrvRecordMonitor(final String hostName, final long rescanFrequencyMillis, final long noRecordsRescanFrequencyMillis,
-                               final DnsSrvRecordInitializer dnsSrvRecordInitializer, final ClusterId clusterId,
-                               final DnsResolver dnsResolver) {
+    DefaultDnsSrvRecordMonitor(final String hostName, final String srvServiceName, final long rescanFrequencyMillis, final long noRecordsRescanFrequencyMillis,
+            final DnsSrvRecordInitializer dnsSrvRecordInitializer, final ClusterId clusterId,
+            final DnsResolver dnsResolver) {
         this.hostName = hostName;
+        this.srvServiceName = srvServiceName;
         this.rescanFrequencyMillis = rescanFrequencyMillis;
         this.noRecordsRescanFrequencyMillis = noRecordsRescanFrequencyMillis;
         this.dnsSrvRecordInitializer = dnsSrvRecordInitializer;
@@ -75,7 +77,7 @@ private class DnsSrvRecordMonitorRunnable implements Runnable {
         public void run() {
             while (!isClosed && shouldContinueMonitoring()) {
                 try {
-                    List<String> resolvedHostNames = dnsResolver.resolveHostFromSrvRecords(hostName);
+                    List<String> resolvedHostNames = dnsResolver.resolveHostFromSrvRecords(hostName, srvServiceName);
                     Set<ServerAddress> hosts = createServerAddressSet(resolvedHostNames);
 
                     if (isClosed) {

driver-core/src/main/com/mongodb/internal/connection/DefaultDnsSrvRecordMonitorFactory.java

@@ -36,8 +36,8 @@ public DefaultDnsSrvRecordMonitorFactory(final ClusterId clusterId, final Server
     }
 
     @Override
-    public DnsSrvRecordMonitor create(final String hostName, final DnsSrvRecordInitializer dnsSrvRecordInitializer) {
-        return new DefaultDnsSrvRecordMonitor(hostName, DEFAULT_RESCAN_FREQUENCY_MILLIS, noRecordsRescanFrequency, dnsSrvRecordInitializer,
-                clusterId, new DefaultDnsResolver());
+    public DnsSrvRecordMonitor create(final String hostName, final String srvServiceName, final DnsSrvRecordInitializer dnsSrvRecordInitializer) {
+        return new DefaultDnsSrvRecordMonitor(hostName, srvServiceName, DEFAULT_RESCAN_FREQUENCY_MILLIS, noRecordsRescanFrequency,
+                dnsSrvRecordInitializer, clusterId, new DefaultDnsResolver());
     }
 }

driver-core/src/main/com/mongodb/internal/connection/DnsMultiServerCluster.java

@@ -39,7 +39,8 @@ public DnsMultiServerCluster(final ClusterId clusterId, final ClusterSettings se
                                  final DnsSrvRecordMonitorFactory dnsSrvRecordMonitorFactory) {
         super(clusterId, settings, serverFactory);
         notNull("srvHost", settings.getSrvHost());
-        dnsSrvRecordMonitor = dnsSrvRecordMonitorFactory.create(settings.getSrvHost(), new DnsSrvRecordInitializer() {
+        dnsSrvRecordMonitor = dnsSrvRecordMonitorFactory.create(settings.getSrvHost(), settings.getSrvServiceName(),
+                new DnsSrvRecordInitializer() {
             private volatile boolean initialized;
 
             @Override

driver-core/src/main/com/mongodb/internal/connection/DnsSrvRecordMonitorFactory.java

@@ -17,5 +17,5 @@
 package com.mongodb.internal.connection;
 
 public interface DnsSrvRecordMonitorFactory {
-    DnsSrvRecordMonitor create(String hostName, DnsSrvRecordInitializer dnsSrvRecordInitializer);
+    DnsSrvRecordMonitor create(String hostName, String srvServiceName, DnsSrvRecordInitializer dnsSrvRecordInitializer);
 }

driver-core/src/main/com/mongodb/internal/connection/LoadBalancedCluster.java

@@ -102,7 +102,7 @@ final class LoadBalancedCluster implements Cluster {
             initializationCompleted = true;
         } else {
             notNull("dnsSrvRecordMonitorFactory", dnsSrvRecordMonitorFactory);
-            dnsSrvRecordMonitor = dnsSrvRecordMonitorFactory.create(settings.getSrvHost(), new DnsSrvRecordInitializer() {
+            dnsSrvRecordMonitor = dnsSrvRecordMonitorFactory.create(settings.getSrvHost(), settings.getSrvServiceName(), new DnsSrvRecordInitializer() {
 
                 @Override
                 public void initialize(final Collection<ServerAddress> hosts) {

driver-core/src/main/com/mongodb/internal/dns/DefaultDnsResolver.java

@@ -52,16 +52,17 @@ The priority and weight are ignored, and we just concatenate the host (after rem
       domain equal to the domain of the srvHost.
     */
     @Override
-    public List<String> resolveHostFromSrvRecords(final String srvHost) {
+    public List<String> resolveHostFromSrvRecords(final String srvHost, final String srvServiceName) {
         String srvHostDomain = srvHost.substring(srvHost.indexOf('.') + 1);
         List<String> srvHostDomainParts = asList(srvHostDomain.split("\\."));
         List<String> hosts = new ArrayList<String>();
         InitialDirContext dirContext = createDnsDirContext();
         try {
-            Attributes attributes = dirContext.getAttributes("_mongodb._tcp." + srvHost, new String[]{"SRV"});
+            String resourceRecordName = "_" + srvServiceName + "._tcp." + srvHost;
+            Attributes attributes = dirContext.getAttributes(resourceRecordName, new String[]{"SRV"});
             Attribute attribute = attributes.get("SRV");
             if (attribute == null) {
-                throw new MongoConfigurationException("No SRV records available for host " + srvHost);
+                throw new MongoConfigurationException(format("No SRV records available for %s", resourceRecordName));
             }
             NamingEnumeration<?> srvRecordEnumeration = attribute.getAll();
             while (srvRecordEnumeration.hasMore()) {

driver-core/src/main/com/mongodb/internal/dns/DnsResolver.java

@@ -25,7 +25,7 @@
  */
 public interface DnsResolver {
 
-    List<String> resolveHostFromSrvRecords(String srvHost);
+    List<String> resolveHostFromSrvRecords(String srvHost, String srvServiceName);
 
     String resolveAdditionalQueryParametersFromTxtRecords(String host);
 }