Add no-op DNS resolver

Author: dlon

mullvad-api/src/lib.rs

@@ -311,6 +311,7 @@ pub trait DnsResolver: 'static + Send + Sync {
     async fn resolve(&self, host: String) -> io::Result<Vec<IpAddr>>;
 }
 
+/// DNS resolver that relies on `ToSocketAddrs` (`getaddrinfo`).
 pub struct DefaultDnsResolver;
 
 #[async_trait]
@@ -326,6 +327,16 @@ impl DnsResolver for DefaultDnsResolver {
     }
 }
 
+/// DNS resolver that always returns no results
+pub struct NullDnsResolver;
+
+#[async_trait]
+impl DnsResolver for NullDnsResolver {
+    async fn resolve(&self, _host: String) -> io::Result<Vec<IpAddr>> {
+        Ok(vec![])
+    }
+}
+
 /// A type that helps with the creation of API connections.
 pub struct Runtime {
     handle: tokio::runtime::Handle,

mullvad-problem-report/src/lib.rs

@@ -1,4 +1,4 @@
-use mullvad_api::{proxy::ApiConnectionMode, DefaultDnsResolver};
+use mullvad_api::{proxy::ApiConnectionMode, NullDnsResolver};
 use regex::Regex;
 use std::{
     borrow::Cow,
@@ -292,8 +292,7 @@ async fn send_problem_report_inner(
 ) -> Result<(), Error> {
     let metadata = ProblemReport::parse_metadata(report_content).unwrap_or_else(metadata::collect);
     let api_runtime = mullvad_api::Runtime::with_cache(
-        // This is irrelevant since no DNS lookups will be made
-        DefaultDnsResolver,
+        NullDnsResolver,
         cache_dir,
         false,
         #[cfg(target_os = "android")]

mullvad-setup/src/main.rs

@@ -1,7 +1,7 @@
 use clap::Parser;
 use std::{path::PathBuf, process, str::FromStr, sync::LazyLock, time::Duration};
 
-use mullvad_api::{proxy::ApiConnectionMode, DefaultDnsResolver, DEVICE_NOT_FOUND};
+use mullvad_api::{proxy::ApiConnectionMode, NullDnsResolver, DEVICE_NOT_FOUND};
 use mullvad_management_interface::MullvadProxyClient;
 use mullvad_types::version::ParsedAppVersion;
 use talpid_core::firewall::{self, Firewall};
@@ -152,7 +152,7 @@ async fn remove_device() -> Result<(), Error> {
         .await
         .map_err(Error::ReadDeviceCacheError)?;
     if let Some(device) = state.into_device() {
-        let api_runtime = mullvad_api::Runtime::with_cache(DefaultDnsResolver, &cache_path, false)
+        let api_runtime = mullvad_api::Runtime::with_cache(NullDnsResolver, &cache_path, false)
             .await
             .map_err(Error::RpcInitializationError)?;