Have DNS manager select the best DNS config

4 files changed, 33 insertions, 20 deletions

diff --git a/talpid-core/src/dns/macos.rs b/talpid-core/src/dns/macos.rs
index 1f63310449..fe7501d905 100644
--- a/talpid-core/src/dns/macos.rs
+++ b/talpid-core/src/dns/macos.rs
@@ -72,7 +72,9 @@ impl State {
         if let Some(tunnel_tx) = self.tunnel_tx.upgrade() {
             match parse_sc_config(&self.backup) {
                 Ok(config) => {
-                    let _ = tunnel_tx.unbounded_send(TunnelCommand::HostDnsConfig(config));
+                    // TODO: do better filtering to get the best resolver
+                    let _ = tunnel_tx
+                        .unbounded_send(TunnelCommand::HostDnsConfig(config.into_iter().next()));
                 }
                 Err(err) => {
                     log::error!("Failed to parse host's DNS config: {}", err);
@@ -319,7 +321,7 @@ impl DnsMonitor {
         result_rx.recv().unwrap()
     }
     /// Get the system config without our changes
-    pub fn get_system_config(&self) -> Result<HashMap<String, Vec<IpAddr>>> {
+    pub fn get_system_config(&self) -> Result<Option<(String, Vec<IpAddr>)>> {
         self.state
             .lock()
             .as_ref()
@@ -330,7 +332,7 @@ impl DnsMonitor {
 
 fn parse_sc_config(
     config: &HashMap<String, Option<DnsSettings>>,
-) -> Result<HashMap<String, Vec<IpAddr>>> {
+) -> Result<Option<(String, Vec<IpAddr>)>> {
     config
         .iter()
         .filter_map(|(path, maybe_config)| {
@@ -344,7 +346,8 @@ fn parse_sc_config(
             let addresses = settings.interface_config(path.as_str())?;
             Ok((settings.name.clone(), addresses))
         })
-        .collect::<Result<_>>()
+        .next()
+        .transpose()
 }
 
 /// Creates a `SCDynamicStore` that watches all network interfaces for changes to the DNS settings.
diff --git a/talpid-core/src/dns/mod.rs b/talpid-core/src/dns/mod.rs
index a941cf783e..5a7b5c0dec 100644
--- a/talpid-core/src/dns/mod.rs
+++ b/talpid-core/src/dns/mod.rs
@@ -1,7 +1,5 @@
 #[cfg(target_os = "linux")]
 use crate::routing::RouteManagerHandle;
-#[cfg(target_os = "macos")]
-use std::collections::HashMap;
 use std::net::IpAddr;
 
 #[cfg(target_os = "macos")]
@@ -54,7 +52,7 @@ impl DnsMonitor {
     /// Returns a map of interfaces and respective list of resolvers that don't contain our
     /// changes.
     #[cfg(target_os = "macos")]
-    pub fn get_system_config(&self) -> Result<HashMap<String, Vec<IpAddr>>, Error> {
+    pub fn get_system_config(&self) -> Result<Option<(String, Vec<IpAddr>)>, Error> {
         self.inner.get_system_config()
     }
 
diff --git a/talpid-core/src/resolver/mod.rs b/talpid-core/src/resolver/mod.rs
index 28ce99c355..fc3509f513 100644
--- a/talpid-core/src/resolver/mod.rs
+++ b/talpid-core/src/resolver/mod.rs
@@ -1,7 +1,7 @@
 use socket2::{Domain, Socket, Type};
 
 use std::{
-    collections::{BTreeSet, HashMap},
+    collections::BTreeSet,
     ffi::CString,
     future::Future,
     io,
@@ -151,7 +151,7 @@ type ExcludedUpstreamResolver = AsyncResolver<GenericConnection, OurConnectionPr
 
 #[derive(Debug, PartialEq, Clone)]
 pub(crate) enum ResolverState {
-    Active(HashMap<String, Vec<IpAddr>>),
+    Active(Option<(String, Vec<IpAddr>)>),
     Inactive,
     Shutdown,
 }
@@ -208,7 +208,7 @@ impl ResolverHandle {
     /// Enable the resolver
     pub async fn set_active(
         &self,
-        config: HashMap<String, Vec<IpAddr>>,
+        config: Option<(String, Vec<IpAddr>)>,
     ) -> Result<ResolverStateToggleResult, Error> {
         self.set_state(ResolverState::Active(config)).await
     }
@@ -373,15 +373,13 @@ impl FilteringResolver {
 
     fn get_resolver_config(&self) -> (&str, &[IpAddr]) {
         match &self.resolver_state {
-            ResolverState::Active(resolvers) => {
+            ResolverState::Active(ref resolvers) => {
                 // TODO: actually pick the best resolver
                 resolvers
-                    .iter()
-                    // ignore anay config with loopback addresses
+                    .as_ref()
                     .filter(|(_, addresses)| {
                         !addresses.iter().any(|ip| ip.is_loopback())
                     })
-                    .next()
                     .map(|(interface_name, addresses)| (interface_name.as_str(), addresses.as_slice()))
                     .unwrap_or(("", &[]))
             }
@@ -658,7 +656,7 @@ impl LookupObject for ForwardLookup {
 #[cfg(test)]
 mod test {
     use super::*;
-    use std::{fs, net::UdpSocket};
+    use std::{fs, net::UdpSocket, process::Command};
     use subslice::SubsliceExt;
 
     fn random_port() -> u16 {
@@ -668,7 +666,7 @@ mod test {
 
     const NAMESERVER: &[u8] = b"nameserver";
 
-    fn read_resolvconf() -> HashMap<String, Vec<IpAddr>> {
+    fn read_resolvconf() -> Option<(String, Vec<IpAddr>)> {
         let contents = fs::read("/etc/resolv.conf").unwrap();
         let nameserver_index = contents
             .find(NAMESERVER)
@@ -681,9 +679,23 @@ mod test {
 
         let resolver_ip =
             IpAddr::from_str(std::str::from_utf8(ip_addr_subslice).unwrap().trim()).unwrap();
-        let mut map = HashMap::new();
-        map.insert("".to_string(), vec![resolver_ip]);
-        map
+        let route_output = String::from_utf8(
+            Command::new("route")
+                .arg("get")
+                .arg(resolver_ip.to_string())
+                .output()
+                .expect("Failed to run 'route get'")
+                .stdout,
+        )
+        .unwrap();
+
+        let mut output_parts = route_output.split_whitespace();
+        while let Some(part) = output_parts.next() {
+            if part.trim() == "interface:" {
+                return Some((output_parts.next().unwrap().to_string(), vec![resolver_ip]));
+            }
+        }
+        panic!("Couldn't deduce interface")
     }
 
     async fn start_resolver() -> (
diff --git a/talpid-core/src/tunnel_state_machine/mod.rs b/talpid-core/src/tunnel_state_machine/mod.rs
index 0130a4a42d..a6696117fc 100644
--- a/talpid-core/src/tunnel_state_machine/mod.rs
+++ b/talpid-core/src/tunnel_state_machine/mod.rs
@@ -192,7 +192,7 @@ pub enum TunnelCommand {
     SetCustomResolver(bool, oneshot::Sender<Result<(), crate::resolver::Error>>),
     /// Receive up-to-date system DNS config. It should never contain our changes to the DNS.
     #[cfg(target_os = "macos")]
-    HostDnsConfig(HashMap<String, Vec<IpAddr>>),
+    HostDnsConfig(Option<(String, Vec<IpAddr>)>),
 }
 
 type TunnelCommandReceiver = stream::Fuse<mpsc::UnboundedReceiver<TunnelCommand>>;