GODRIVER-2086 Allow custom SRV service names with URI option srvServi…

…ceName (mongodb#734)

data/initial-dns-seedlist-discovery/replica-set/srv-service-name.json

@@ -0,0 +1,16 @@
+{
+  "uri": "mongodb+srv://test22.test.build.10gen.cc/?srvServiceName=customname",
+  "seeds": [
+    "localhost.test.build.10gen.cc:27017",
+    "localhost.test.build.10gen.cc:27018"
+  ],
+  "hosts": [
+    "localhost:27017",
+    "localhost:27018",
+    "localhost:27019"
+  ],
+  "options": {
+    "ssl": true,
+    "srvServiceName": "customname"
+  }
+}

data/initial-dns-seedlist-discovery/replica-set/srv-service-name.yml

@@ -0,0 +1,11 @@
+uri: "mongodb+srv://test22.test.build.10gen.cc/?srvServiceName=customname"
+seeds:
+    - localhost.test.build.10gen.cc:27017
+    - localhost.test.build.10gen.cc:27018
+hosts:
+    - localhost:27017
+    - localhost:27018
+    - localhost:27019
+options:
+    ssl: true
+    srvServiceName: "customname"

data/uri-options/srv-service-name-option.json

@@ -0,0 +1,24 @@
+{
+  "tests": [
+    {
+      "description": "SRV URI with custom srvServiceName",
+      "uri": "mongodb+srv://test22.test.build.10gen.cc/?srvServiceName=customname",
+      "valid": true,
+      "warning": false,
+      "hosts": null,
+      "auth": null,
+      "options": {
+        "srvServiceName": "customname"
+      }
+    },
+    {
+      "description": "Non-SRV URI with custom srvServiceName",
+      "uri": "mongodb://example.com/?srvServiceName=customname",
+      "valid": false,
+      "warning": true,
+      "hosts": null,
+      "auth": null,
+      "options": {}
+    }
+  ]
+}

data/uri-options/srv-service-name-option.yml

@@ -0,0 +1,16 @@
+tests:
+    - description: "SRV URI with custom srvServiceName"
+      uri: "mongodb+srv://test22.test.build.10gen.cc/?srvServiceName=customname"
+      valid: true
+      warning: false
+      hosts: ~
+      auth: ~
+      options:
+          srvServiceName: "customname"
+    - description: "Non-SRV URI with custom srvServiceName"
+      uri: "mongodb://example.com/?srvServiceName=customname"
+      valid: false
+      warning: true
+      hosts: ~
+      auth: ~
+      options: {}

internal/testutil/helpers/helpers.go

@@ -150,6 +150,8 @@ func VerifyConnStringOptions(t *testing.T, cs connstring.ConnString, options map
 			require.Equal(t, value, cs.RetryWrites)
 		case "serverselectiontimeoutms":
 			require.Equal(t, value, float64(cs.ServerSelectionTimeout/time.Millisecond))
+		case "srvservicename":
+			require.Equal(t, value, cs.SRVServiceName)
 		case "ssl", "tls":
 			require.Equal(t, value, cs.SSL)
 		case "sockettimeoutms":

mongo/client.go

@@ -375,10 +375,16 @@ func (c *Client) configure(opts *options.ClientOptions) error {
 	// ClusterClock
 	c.clock = new(session.ClusterClock)
 
-	// Pass down URI so topology can determine whether or not SRV polling is required
-	topologyOpts = append(topologyOpts, topology.WithURI(func(uri string) string {
-		return opts.GetURI()
-	}))
+	// Pass down URI and SRV service name so topology can poll SRV records correctly
+	topologyOpts = append(topologyOpts,
+		topology.WithURI(func(uri string) string { return opts.GetURI() }),
+		topology.WithSRVServiceName(func(srvName string) string {
+			if opts.SRVServiceName != nil {
+				return *opts.SRVServiceName
+			}
+			return ""
+		}),
+	)
 
 	// AppName
 	var appName string
@@ -669,9 +675,9 @@ func (c *Client) configure(opts *options.ClientOptions) error {
 
 	// Deployment
 	if opts.Deployment != nil {
-		// topology options: WithSeedlist and WithURI
+		// topology options: WithSeedlist, WithURI and WithSRVServiceName
 		// server options: WithClock and WithConnectionOptions
-		if len(serverOpts) > 2 || len(topologyOpts) > 2 {
+		if len(serverOpts) > 2 || len(topologyOpts) > 3 {
 			return errors.New("cannot specify topology or server options with a deployment")
 		}
 		c.deployment = opts.Deployment

mongo/integration/initial_dns_seedlist_discovery_test.go

@@ -135,6 +135,9 @@ func verifyConnstringOptions(mt *mtest.T, expected bson.Raw, cs connstring.ConnS
 			lb := opt.Boolean()
 			assert.True(mt, cs.LoadBalancedSet, "expected cs.LoadBalancedSet set to be true, got false")
 			assert.Equal(mt, lb, cs.LoadBalanced, "expected cs.LoadBalanced to be %v, got %v", lb, cs.LoadBalanced)
+		case "srvServiceName":
+			srvName := opt.StringValue()
+			assert.Equal(mt, srvName, cs.SRVServiceName, "expected cs.SRVServiceName to be %q, got %q", srvName, cs.SRVServiceName)
 		default:
 			mt.Fatalf("unrecognized connstring option %v", key)
 		}

mongo/options/clientoptions.go

@@ -121,6 +121,7 @@ type ClientOptions struct {
 	ServerAPIOptions         *ServerAPIOptions
 	ServerSelectionTimeout   *time.Duration
 	SocketTimeout            *time.Duration
+	SRVServiceName           *string
 	TLSConfig                *tls.Config
 	WriteConcern             *writeconcern.WriteConcern
 	ZlibLevel                *int
@@ -338,6 +339,10 @@ func (c *ClientOptions) ApplyURI(uri string) *ClientOptions {
 		c.SocketTimeout = &cs.SocketTimeout
 	}
 
+	if cs.SRVServiceName != "" {
+		c.SRVServiceName = &cs.SRVServiceName
+	}
+
 	if cs.SSL {
 		tlsConfig := new(tls.Config)
 
@@ -760,6 +765,14 @@ func (c *ClientOptions) SetServerAPIOptions(opts *ServerAPIOptions) *ClientOptio
 	return c
 }
 
+// SetSRVServiceName specifies a custom SRV service name to use in SRV polling. To use a custom SRV service name
+// in SRV discovery, this function must be called before ApplyURI. This can also be set through the "srvServiceName"
+// URI option.
+func (c *ClientOptions) SetSRVServiceName(srvName string) *ClientOptions {
+	c.SRVServiceName = &srvName
+	return c
+}
+
 // MergeClientOptions combines the given *ClientOptions into a single *ClientOptions in a last one wins fashion.
 // The specified options are merged with the existing options on the client, with the specified options taking
 // precedence.
@@ -849,6 +862,9 @@ func MergeClientOptions(opts ...*ClientOptions) *ClientOptions {
 		if opt.SocketTimeout != nil {
 			c.SocketTimeout = opt.SocketTimeout
 		}
+		if opt.SRVServiceName != nil {
+			c.SRVServiceName = opt.SRVServiceName
+		}
 		if opt.TLSConfig != nil {
 			c.TLSConfig = opt.TLSConfig
 		}

x/mongo/driver/connstring/connstring.go

@@ -97,6 +97,7 @@ type ConnString struct {
 	ServerSelectionTimeoutSet          bool
 	SocketTimeout                      time.Duration
 	SocketTimeoutSet                   bool
+	SRVServiceName                     string
 	SSL                                bool
 	SSLSet                             bool
 	SSLClientCertificateKeyFile        string
@@ -254,14 +255,25 @@ func (p *parser) parse(original string) error {
 		hosts = uri[:idx]
 	}
 
-	var connectionArgsFromTXT []string
 	parsedHosts := strings.Split(hosts, ",")
+	uri = uri[len(hosts):]
+	extractedDatabase, err := extractDatabaseFromURI(uri)
+	if err != nil {
+		return err
+	}
+
+	uri = extractedDatabase.uri
+	p.Database = extractedDatabase.db
+
+	// grab connection arguments from URI
+	connectionArgsFromQueryString, err := extractQueryArgsFromURI(uri)
+	if err != nil {
+		return err
+	}
 
+	// grab connection arguments from TXT record and enable SSL if "mongodb+srv://"
+	var connectionArgsFromTXT []string
 	if p.Scheme == SchemeMongoDBSRV {
-		parsedHosts, err = p.dnsResolver.ParseHosts(hosts, true)
-		if err != nil {
-			return err
-		}
 		connectionArgsFromTXT, err = p.dnsResolver.GetConnectionArgsFromTXT(hosts)
 		if err != nil {
 			return err
@@ -272,35 +284,32 @@ func (p *parser) parse(original string) error {
 		p.SSLSet = true
 	}
 
-	for _, host := range parsedHosts {
-		err = p.addHost(host)
+	// add connection arguments from URI and TXT records to connstring
+	connectionArgPairs := append(connectionArgsFromTXT, connectionArgsFromQueryString...)
+	for _, pair := range connectionArgPairs {
+		err := p.addOption(pair)
 		if err != nil {
-			return internal.WrapErrorf(err, "invalid host \"%s\"", host)
+			return err
 		}
 	}
-	if len(p.Hosts) == 0 {
-		return fmt.Errorf("must have at least 1 host")
-	}
 
-	uri = uri[len(hosts):]
-
-	extractedDatabase, err := extractDatabaseFromURI(uri)
-	if err != nil {
-		return err
+	// do SRV lookup if "mongodb+srv://"
+	if p.Scheme == SchemeMongoDBSRV {
+		parsedHosts, err = p.dnsResolver.ParseHosts(hosts, p.SRVServiceName, true)
+		if err != nil {
+			return err
+		}
 	}
 
-	uri = extractedDatabase.uri
-	p.Database = extractedDatabase.db
-
-	connectionArgsFromQueryString, err := extractQueryArgsFromURI(uri)
-	connectionArgPairs := append(connectionArgsFromTXT, connectionArgsFromQueryString...)
-
-	for _, pair := range connectionArgPairs {
-		err = p.addOption(pair)
+	for _, host := range parsedHosts {
+		err = p.addHost(host)
 		if err != nil {
-			return err
+			return internal.WrapErrorf(err, "invalid host \"%s\"", host)
 		}
 	}
+	if len(p.Hosts) == 0 {
+		return fmt.Errorf("must have at least 1 host")
+	}
 
 	err = p.setDefaultAuthParams(extractedDatabase.db)
 	if err != nil {
@@ -762,6 +771,20 @@ func (p *parser) addOption(pair string) error {
 		}
 		p.SocketTimeout = time.Duration(n) * time.Millisecond
 		p.SocketTimeoutSet = true
+	case "srvservicename":
+		// srvServiceName can only be set on URIs with the "mongodb+srv" scheme
+		if p.Scheme != SchemeMongoDBSRV {
+			return fmt.Errorf("cannot specify srvServiceName on non-SRV URI")
+		}
+
+		// srvServiceName must be between 1 and 62 characters according to
+		// our specification. Empty service names are not valid, and the service
+		// name (including prepended underscore) should not exceed the 63 character
+		// limit for DNS query subdomains.
+		if len(value) < 1 || len(value) > 62 {
+			return fmt.Errorf("srvServiceName value must be between 1 and 62 characters")
+		}
+		p.SRVServiceName = value
 	case "ssl", "tls":
 		switch value {
 		case "true":

x/mongo/driver/dns/dns.go

@@ -24,14 +24,14 @@ type Resolver struct {
 // DefaultResolver is a Resolver that uses the default Resolver from the net package.
 var DefaultResolver = &Resolver{net.LookupSRV, net.LookupTXT}
 
-// ParseHosts uses the srv string to get the hosts.
-func (r *Resolver) ParseHosts(host string, stopOnErr bool) ([]string, error) {
+// ParseHosts uses the srv string and service name to get the hosts.
+func (r *Resolver) ParseHosts(host string, srvName string, stopOnErr bool) ([]string, error) {
 	parsedHosts := strings.Split(host, ",")
 
 	if len(parsedHosts) != 1 {
 		return nil, fmt.Errorf("URI with SRV must include one and only one hostname")
 	}
-	return r.fetchSeedlistFromSRV(parsedHosts[0], stopOnErr)
+	return r.fetchSeedlistFromSRV(parsedHosts[0], srvName, stopOnErr)
 }
 
 // GetConnectionArgsFromTXT gets the TXT record associated with the host and returns the connection arguments.
@@ -64,7 +64,7 @@ func (r *Resolver) GetConnectionArgsFromTXT(host string) ([]string, error) {
 	return connectionArgsFromTXT, nil
 }
 
-func (r *Resolver) fetchSeedlistFromSRV(host string, stopOnErr bool) ([]string, error) {
+func (r *Resolver) fetchSeedlistFromSRV(host string, srvName string, stopOnErr bool) ([]string, error) {
 	var err error
 
 	_, _, err = net.SplitHostPort(host)
@@ -75,7 +75,11 @@ func (r *Resolver) fetchSeedlistFromSRV(host string, stopOnErr bool) ([]string,
 		return nil, fmt.Errorf("URI with srv must not include a port number")
 	}
 
-	_, addresses, err := r.LookupSRV("mongodb", "tcp", host)
+	// default to "mongodb" as service name if not supplied
+	if srvName == "" {
+		srvName = "mongodb"
+	}
+	_, addresses, err := r.LookupSRV(srvName, "tcp", host)
 	if err != nil {
 		return nil, err
 	}

x/mongo/driver/topology/topology.go

@@ -527,7 +527,7 @@ func (t *Topology) pollSRVRecords() {
 			break
 		}
 
-		parsedHosts, err := t.dnsResolver.ParseHosts(hosts, false)
+		parsedHosts, err := t.dnsResolver.ParseHosts(hosts, t.cfg.srvServiceName, false)
 		// DNS problem or no verified hosts returned
 		if err != nil || len(parsedHosts) == 0 {
 			if !t.pollHeartbeatTime.Load().(bool) {

x/mongo/driver/topology/topology_options.go

@@ -36,6 +36,7 @@ type config struct {
 	uri                    string
 	serverSelectionTimeout time.Duration
 	serverMonitor          *event.ServerMonitor
+	srvServiceName         string
 	loadBalanced           bool
 }
 
@@ -304,6 +305,22 @@ func WithURI(fn func(string) string) Option {
 	}
 }
 
+// WithLoadBalanced specifies whether or not the cluster is behind a load balancer.
+func WithLoadBalanced(fn func(bool) bool) Option {
+	return func(cfg *config) error {
+		cfg.loadBalanced = fn(cfg.loadBalanced)
+		return nil
+	}
+}
+
+// WithSRVServiceName specifies the SRV service name that was used to create the topology.
+func WithSRVServiceName(fn func(string) string) Option {
+	return func(cfg *config) error {
+		cfg.srvServiceName = fn(cfg.srvServiceName)
+		return nil
+	}
+}
+
 // addCACertFromFile adds a root CA certificate to the configuration given a path
 // to the containing file.
 func addCACertFromFile(cfg *tls.Config, file string) error {
@@ -422,11 +439,3 @@ func addClientCertFromFile(cfg *tls.Config, clientFile, keyPasswd string) (strin
 
 	return x509CertSubject(crt), nil
 }
-
-// WithLoadBalanced specifies whether or not the cluster is behind a load balancer.
-func WithLoadBalanced(fn func(bool) bool) Option {
-	return func(cfg *config) error {
-		cfg.loadBalanced = fn(cfg.loadBalanced)
-		return nil
-	}
-}