RUST-911: Add srvServiceName URI option

src/client/options.rs

@@ -89,6 +89,7 @@ const URI_OPTIONS: &[&str] = &[
     "waitqueuetimeoutms",
     "wtimeoutms",
     "zlibcompressionlevel",
+    "srvservicename",
 ];
 
 /// Reserved characters as defined by [Section 2.2 of RFC-3986](https://tools.ietf.org/html/rfc3986#section-2.2).
@@ -521,6 +522,9 @@ pub struct ClientOptions {
     /// By default, no default database is specified.
     pub default_database: Option<String>,
 
+    /// Overrides the default "mongodb" service name for SRV lookup in both discovery and polling
+    pub srv_service_name: Option<String>,
+
     #[builder(setter(skip))]
     #[derivative(Debug = "ignore")]
     pub(crate) socket_timeout: Option<Duration>,
@@ -676,6 +680,8 @@ impl Serialize for ClientOptions {
             loadbalanced: &'a Option<bool>,
 
             srvmaxhosts: Option<i32>,
+
+            srvservicename: &'a Option<String>,
         }
 
         let client_options = ClientOptionsHelper {
@@ -709,6 +715,7 @@ impl Serialize for ClientOptions {
                 .map(|v| v.try_into())
                 .transpose()
                 .map_err(serde::ser::Error::custom)?,
+            srvservicename: &self.srv_service_name,
         };
 
         client_options.serialize(serializer)
@@ -865,6 +872,9 @@ pub struct ConnectionString {
     /// Limit on the number of mongos connections that may be created for sharded topologies.
     pub srv_max_hosts: Option<u32>,
 
+    /// Overrides the default "mongodb" service name for SRV lookup in both discovery and polling
+    pub srv_service_name: Option<String>,
+
     wait_queue_timeout: Option<Duration>,
     tls_insecure: Option<bool>,
 
@@ -904,7 +914,7 @@ impl HostInfo {
         Ok(match self {
             Self::HostIdentifiers(hosts) => ResolvedHostInfo::HostIdentifiers(hosts),
             Self::DnsRecord(hostname) => {
-                let mut resolver = SrvResolver::new(resolver_config.clone()).await?;
+                let mut resolver = SrvResolver::new(resolver_config.clone(), None).await?;
                 let config = resolver.resolve_client_options(&hostname).await?;
                 ResolvedHostInfo::DnsRecord { hostname, config }
             }
@@ -1486,6 +1496,12 @@ impl ConnectionString {
             ConnectionStringParts::default()
         };
 
+        if conn_str.srv_service_name.is_some() && !srv {
+            return Err(Error::invalid_argument(
+                "srvServiceName cannot be specified with a non-SRV URI",
+            ));
+        }
+
         if let Some(srv_max_hosts) = conn_str.srv_max_hosts {
             if !srv {
                 return Err(Error::invalid_argument(
@@ -1976,6 +1992,9 @@ impl ConnectionString {
             k @ "srvmaxhosts" => {
                 self.srv_max_hosts = Some(get_u32!(value, k));
             }
+            "srvservicename" => {
+                self.srv_service_name = Some(value.to_string());
+            }
             k @ "tls" | k @ "ssl" => {
                 let tls = get_bool!(value, k);
 

src/client/options/parse.rs

@@ -159,6 +159,7 @@ impl ClientOptions {
             #[cfg(feature = "tracing-unstable")]
             tracing_max_document_length_bytes: None,
             srv_max_hosts: conn_str.srv_max_hosts,
+            srv_service_name: conn_str.srv_service_name,
         }
     }
 }

src/sdam/srv_polling.rs

@@ -130,7 +130,11 @@ impl SrvPollingMonitor {
             return Ok(resolver);
         }
 
-        let resolver = SrvResolver::new(self.client_options.resolver_config().cloned()).await?;
+        let resolver = SrvResolver::new(
+            self.client_options.resolver_config().cloned(),
+            Option::Some(self.client_options.clone()),
+        )
+        .await?;
 
         // Since the connection was not `Some` above, this will always insert the new connection and
         // return a reference to it.

src/srv.rs

@@ -2,7 +2,11 @@ use std::time::Duration;
 
 #[cfg(feature = "dns-resolver")]
 use crate::error::ErrorKind;
-use crate::{client::options::ResolverConfig, error::Result, options::ServerAddress};
+use crate::{
+    client::options::ResolverConfig,
+    error::Result,
+    options::{ClientOptions, ServerAddress},
+};
 
 #[derive(Debug)]
 pub(crate) struct ResolvedConfig {
@@ -90,14 +94,21 @@ pub(crate) enum DomainMismatch {
 #[cfg(feature = "dns-resolver")]
 pub(crate) struct SrvResolver {
     resolver: crate::runtime::AsyncResolver,
+    client_options: Option<ClientOptions>,
 }
 
 #[cfg(feature = "dns-resolver")]
 impl SrvResolver {
-    pub(crate) async fn new(config: Option<ResolverConfig>) -> Result<Self> {
+    pub(crate) async fn new(
+        config: Option<ResolverConfig>,
+        client_options: Option<ClientOptions>,
+    ) -> Result<Self> {
         let resolver = crate::runtime::AsyncResolver::new(config.map(|c| c.inner)).await?;
 
-        Ok(Self { resolver })
+        Ok(Self {
+            resolver,
+            client_options,
+        })
     }
 
     pub(crate) async fn resolve_client_options(
@@ -149,7 +160,15 @@ impl SrvResolver {
         original_hostname: &str,
         dm: DomainMismatch,
     ) -> Result<LookupHosts> {
-        let lookup_hostname = format!("_mongodb._tcp.{}", original_hostname);
+        let default_service_name = "mongodb".to_string();
+        let service_name = match &self.client_options {
+            None => default_service_name,
+            Some(opts) => opts
+                .srv_service_name
+                .clone()
+                .unwrap_or(default_service_name),
+        };
+        let lookup_hostname = format!("_{}._tcp.{}", service_name, original_hostname);
         self.get_srv_hosts_unvalidated(&lookup_hostname)
             .await?
             .validate(original_hostname, dm)

src/test/spec/json/initial-dns-seedlist-discovery/README.md

@@ -0,0 +1,182 @@
+# Initial DNS Seedlist Discovery tests
+
+This directory contains platform-independent tests that drivers can use to prove their conformance to the Initial DNS
+Seedlist Discovery spec.
+
+## Prose Tests
+
+For the following prose tests, it is assumed drivers are be able to stub DNS results to easily test invalid DNS
+resolution results.
+
+### 1. Allow SRVs with fewer than 3 `.` separated parts
+
+When running validation on an SRV string before DNS resolution, do not throw a error due to number of SRV parts.
+
+- `mongodb+srv://localhost`
+- `mongodb+srv://mongo.local`
+
+### 2. Throw when return address does not end with SRV domain
+
+When given a returned address that does NOT end with the original SRV's domain name, throw a runtime error.
+
+For this test, run each of the following cases:
+
+- the SRV `mongodb+srv://localhost` resolving to `localhost.mongodb`
+- the SRV `mongodb+srv://mongo.local` resolving to `test_1.evil.local`
+- the SRV `mongodb+srv://blogs.mongodb.com` resolving to `blogs.evil.com`
+
+Remember, the domain of an SRV with one or two `.` separated parts is the SRVs entire hostname.
+
+### 3. Throw when return address is identical to SRV hostname
+
+When given a returned address that is identical to the SRV hostname and the SRV hostname has fewer than three `.`
+separated parts, throw a runtime error.
+
+For this test, run each of the following cases:
+
+- the SRV `mongodb+srv://localhost` resolving to `localhost`
+- the SRV `mongodb+srv://mongo.local` resolving to `mongo.local`
+
+### 4. Throw when return address does not contain `.` separating shared part of domain
+
+When given a returned address that does NOT share the domain name of the SRV record because it's missing a `.`, throw a
+runtime error.
+
+For this test, run each of the following cases:
+
+- the SRV `mongodb+srv://localhost` resolving to `test_1.cluster_1localhost`
+- the SRV `mongodb+srv://mongo.local` resolving to `test_1.my_hostmongo.local`
+- the SRV `mongodb+srv://blogs.mongodb.com` resolving to `cluster.testmongodb.com`
+
+## Test Setup
+
+The tests in the `replica-set` directory MUST be executed against a three-node replica set on localhost ports 27017,
+27018, and 27019 with replica set name `repl0`.
+
+The tests in the `load-balanced` directory MUST be executed against a load-balanced sharded cluster with the mongos
+servers running on localhost ports 27017 and 27018 and `--loadBalancerPort` 27050 and 27051, respectively (corresponding
+to the script in
+[drivers-evergreen-tools](https://github.com/mongodb-labs/drivers-evergreen-tools/blob/master/.evergreen/run-load-balancer.sh)).
+The load balancers, shard servers, and config servers may run on any open ports.
+
+The tests in the `sharded` directory MUST be executed against a sharded cluster with the mongos servers running on
+localhost ports 27017 and 27018. Shard servers and config servers may run on any open ports.
+
+In all cases, the clusters MUST be started with SSL enabled.
+
+To run the tests that accompany this spec, you need to configure the SRV and TXT records with a real name server. The
+following records are required for these tests:
+
+```dns
+Record                                    TTL    Class   Address
+localhost.test.build.10gen.cc.            86400  IN A    127.0.0.1
+localhost.sub.test.build.10gen.cc.        86400  IN A    127.0.0.1
+
+Record                                      TTL    Class   Port   Target
+_mongodb._tcp.test1.test.build.10gen.cc.    86400  IN SRV  27017  localhost.test.build.10gen.cc.
+_mongodb._tcp.test1.test.build.10gen.cc.    86400  IN SRV  27018  localhost.test.build.10gen.cc.
+_mongodb._tcp.test2.test.build.10gen.cc.    86400  IN SRV  27018  localhost.test.build.10gen.cc.
+_mongodb._tcp.test2.test.build.10gen.cc.    86400  IN SRV  27019  localhost.test.build.10gen.cc.
+_mongodb._tcp.test3.test.build.10gen.cc.    86400  IN SRV  27017  localhost.test.build.10gen.cc.
+_mongodb._tcp.test5.test.build.10gen.cc.    86400  IN SRV  27017  localhost.test.build.10gen.cc.
+_mongodb._tcp.test6.test.build.10gen.cc.    86400  IN SRV  27017  localhost.test.build.10gen.cc.
+_mongodb._tcp.test7.test.build.10gen.cc.    86400  IN SRV  27017  localhost.test.build.10gen.cc.
+_mongodb._tcp.test8.test.build.10gen.cc.    86400  IN SRV  27017  localhost.test.build.10gen.cc.
+_mongodb._tcp.test10.test.build.10gen.cc.   86400  IN SRV  27017  localhost.test.build.10gen.cc.
+_mongodb._tcp.test11.test.build.10gen.cc.   86400  IN SRV  27017  localhost.test.build.10gen.cc.
+_mongodb._tcp.test12.test.build.10gen.cc.   86400  IN SRV  27017  localhost.build.10gen.cc.
+_mongodb._tcp.test13.test.build.10gen.cc.   86400  IN SRV  27017  test.build.10gen.cc.
+_mongodb._tcp.test14.test.build.10gen.cc.   86400  IN SRV  27017  localhost.not-test.build.10gen.cc.
+_mongodb._tcp.test15.test.build.10gen.cc.   86400  IN SRV  27017  localhost.test.not-build.10gen.cc.
+_mongodb._tcp.test16.test.build.10gen.cc.   86400  IN SRV  27017  localhost.test.build.not-10gen.cc.
+_mongodb._tcp.test17.test.build.10gen.cc.   86400  IN SRV  27017  localhost.test.build.10gen.not-cc.
+_mongodb._tcp.test18.test.build.10gen.cc.   86400  IN SRV  27017  localhost.sub.test.build.10gen.cc.
+_mongodb._tcp.test19.test.build.10gen.cc.   86400  IN SRV  27017  localhost.evil.build.10gen.cc.
+_mongodb._tcp.test19.test.build.10gen.cc.   86400  IN SRV  27017  localhost.test.build.10gen.cc.
+_mongodb._tcp.test20.test.build.10gen.cc.   86400  IN SRV  27017  localhost.test.build.10gen.cc.
+_mongodb._tcp.test21.test.build.10gen.cc.   86400  IN SRV  27017  localhost.test.build.10gen.cc.
+_customname._tcp.test22.test.build.10gen.cc 86400  IN SRV  27017  localhost.test.build.10gen.cc.
+_mongodb._tcp.test23.test.build.10gen.cc.   86400  IN SRV  8000   localhost.test.build.10gen.cc.
+_mongodb._tcp.test24.test.build.10gen.cc.   86400  IN SRV  8000   localhost.test.build.10gen.cc.
+
+Record                                    TTL    Class   Text
+test5.test.build.10gen.cc.                86400  IN TXT  "replicaSet=repl0&authSource=thisDB"
+test6.test.build.10gen.cc.                86400  IN TXT  "replicaSet=repl0"
+test6.test.build.10gen.cc.                86400  IN TXT  "authSource=otherDB"
+test7.test.build.10gen.cc.                86400  IN TXT  "ssl=false"
+test8.test.build.10gen.cc.                86400  IN TXT  "authSource"
+test10.test.build.10gen.cc.               86400  IN TXT  "socketTimeoutMS=500"
+test11.test.build.10gen.cc.               86400  IN TXT  "replicaS" "et=rep" "l0"
+test20.test.build.10gen.cc.               86400  IN TXT  "loadBalanced=true"
+test21.test.build.10gen.cc.               86400  IN TXT  "loadBalanced=false"
+test24.test.build.10gen.cc.               86400  IN TXT  "loadBalanced=true"
+```
+
+Notes:
+
+- `test4` is omitted deliberately to test what happens with no SRV record.
+- `test9` is missing because it was deleted during the development of the tests.
+- The missing `test.` sub-domain in the SRV record target for `test12` is deliberate.
+- `test22` is used to test a custom service name (`customname`).
+- `test23` and `test24` point to port 8000 (HAProxy) and are used for load-balanced tests.
+
+In our tests we have used `localhost.test.build.10gen.cc` as the domain, and then configured
+`localhost.test.build.10gen.cc` to resolve to 127.0.0.1.
+
+You need to adapt the records shown above to replace `test.build.10gen.cc` with your own domain name, and update the
+"uri" field in the YAML or JSON files in this directory with the actual domain.
+
+## Test Format and Use
+
+These YAML and JSON files contain the following fields:
+
+- `uri`: a `mongodb+srv` connection string
+- `seeds`: the expected set of initial seeds discovered from the SRV record
+- `numSeeds`: the expected number of initial seeds discovered from the SRV record. This is mainly used to test
+    `srvMaxHosts`, since randomly selected hosts cannot be deterministically asserted.
+- `hosts`: the discovered topology's list of hosts once SDAM completes a scan
+- `numHosts`: the expected number of hosts discovered once SDAM completes a scan. This is mainly used to test
+    `srvMaxHosts`, since randomly selected hosts cannot be deterministically asserted.
+- `options`: the parsed [URI options](../../uri-options/uri-options.md) as discovered from the
+    [Connection String](../../connection-string/connection-string-spec.md)'s "Connection Options" component and SRV
+    resolution (e.g. TXT records, implicit `tls` default).
+- `parsed_options`: additional, parsed options from other
+    [Connection String](../../connection-string/connection-string-spec.md) components. This is mainly used for asserting
+    `UserInfo` (as `user` and `password`) and `Auth database` (as `auth_database`).
+- `error`: indicates that the parsing of the URI, or the resolving or contents of the SRV or TXT records included
+    errors.
+- `comment`: a comment to indicate why a test would fail.
+- `ping`: if false, the test runner should not run a "ping" operation.
+
+For each YAML file:
+
+- Create a MongoClient initialized with the `mongodb+srv` connection string.
+- Run a "ping" operation unless `ping` is false or `error` is true.
+
+Assertions:
+
+- If `seeds` is specified, drivers SHOULD verify that the set of hosts in the client's initial seedlist matches the list
+    in `seeds`. If `numSeeds` is specified, drivers SHOULD verify that the size of that set matches `numSeeds`.
+
+- If `hosts` is specified, drivers MUST verify that the set of ServerDescriptions in the client's TopologyDescription
+    eventually matches the list in `hosts`. If `numHosts` is specified, drivers MUST verify that the size of that set
+    matches `numHosts`.
+
+- If `options` is specified, drivers MUST verify each of the values under `options` match the MongoClient's parsed value
+    for that option. There may be other options parsed by the MongoClient as well, which a test does not verify.
+
+- If `parsed_options` is specified, drivers MUST verify that each of the values under `parsed_options` match the
+    MongoClient's parsed value for that option. Supported values include, but are not limited to, `user` and `password`
+    (parsed from `UserInfo`) and `auth_database` (parsed from `Auth database`).
+
+- If `error` is specified and `true`, drivers MUST verify that initializing the MongoClient throws an error. If `error`
+    is not specified or is `false`, both initializing the MongoClient and running a ping operation must succeed without
+    throwing any errors.
+
+- If `ping` is not specified or `true`, drivers MUST verify that running a "ping" operation using the initialized
+    MongoClient succeeds. If `ping` is `false`, drivers MUST NOT run a "ping" operation.
+
+    > **Note:** These tests are expected to be run against MongoDB databases with and without authentication enabled. The
+    > "ping" operation does not require authentication so should succeed with URIs that contain no userinfo (i.e. no
+    > username and password). Tests with URIs that contain userinfo always set `ping` to `false` because some drivers will
+    > fail handshake on a connection if userinfo is provided but incorrect.