RUST-739 Define ResolverConfig wrapper type

Author: patrickfreed

src/client/options/mod.rs

@@ -1,6 +1,8 @@
 #[cfg(all(test, not(feature = "sync")))]
 mod test;
 
+mod resolver_config;
+
 use std::{
     collections::HashSet,
     fmt::{self, Display, Formatter},
@@ -28,7 +30,6 @@ use serde::{
     Deserializer,
 };
 use strsim::jaro_winkler;
-pub use trust_dns_resolver::config::ResolverConfig;
 use typed_builder::TypedBuilder;
 use webpki_roots::TLS_SERVER_ROOTS;
 
@@ -44,6 +45,8 @@ use crate::{
     srv::SrvResolver,
 };
 
+pub use resolver_config::ResolverConfig;
+
 const DEFAULT_PORT: u16 = 27017;
 
 const URI_OPTIONS: &[&str] = &[
@@ -820,7 +823,7 @@ impl ClientOptions {
         options.resolver_config = resolver_config.clone();
 
         if srv {
-            let mut resolver = SrvResolver::new(resolver_config).await?;
+            let mut resolver = SrvResolver::new(resolver_config.map(|config| config.inner)).await?;
             let mut config = resolver
                 .resolve_client_options(&options.hosts[0].hostname)
                 .await?;

src/client/options/resolver_config.rs

@@ -0,0 +1,43 @@
+use trust_dns_resolver::config::ResolverConfig as TrustDnsResolverConfig;
+
+/// Configuration for the upstream nameservers to use for resolution.
+///
+/// This is a thin wrapper around a `trust_dns_resolver::config::ResolverConfig` provided to ensure
+/// API stability.
+#[derive(Clone, Debug, PartialEq)]
+pub struct ResolverConfig {
+    pub(crate) inner: TrustDnsResolverConfig,
+}
+
+impl ResolverConfig {
+    /// Creates a default configuration, using 1.1.1.1, 1.0.0.1 and 2606:4700:4700::1111,
+    /// 2606:4700:4700::1001 (thank you, Cloudflare).
+    ///
+    /// Please see: https://www.cloudflare.com/dns/
+    pub fn cloudflare() -> Self {
+        ResolverConfig {
+            inner: TrustDnsResolverConfig::cloudflare(),
+        }
+    }
+
+    /// Creates a default configuration, using 8.8.8.8, 8.8.4.4 and 2001:4860:4860::8888,
+    /// 2001:4860:4860::8844 (thank you, Google).
+    ///
+    /// Please see Google’s privacy statement for important information about what they track, many
+    /// ISP’s track similar information in DNS.
+    pub fn google() -> Self {
+        ResolverConfig {
+            inner: TrustDnsResolverConfig::google(),
+        }
+    }
+
+    /// Creates a configuration, using 9.9.9.9, 149.112.112.112 and 2620:fe::fe, 2620:fe::fe:9, the
+    /// “secure” variants of the quad9 settings (thank you, Quad9).
+    ///
+    /// Please see: https://www.quad9.net/faq/
+    pub fn quad9() -> Self {
+        ResolverConfig {
+            inner: TrustDnsResolverConfig::quad9(),
+        }
+    }
+}

src/sdam/srv_polling/mod.rs

@@ -128,7 +128,8 @@ impl SrvPollingMonitor {
             return Ok(resolver);
         }
 
-        let resolver = SrvResolver::new(self.client_options.resolver_config.clone()).await?;
+        let resolver =
+            SrvResolver::new(self.client_options.resolver_config.clone().map(|c| c.inner)).await?;
 
         // Since the connection was not `Some` above, this will always insert the new connection and
         // return a reference to it.

src/test/atlas_connectivity.rs

@@ -1,6 +1,5 @@
-use crate::{bson::doc, options::ClientOptions, Client};
+use crate::{bson::doc, client::options::ResolverConfig, options::ClientOptions, Client};
 use bson::Document;
-use trust_dns_resolver::config::ResolverConfig;
 
 async fn run_test(uri_env_var: &str, resolver_config: Option<ResolverConfig>) {
     if std::env::var_os("MONGO_ATLAS_TESTS").is_none() {