Add log which invalid port was tried when failing to select a relay

Author: MarkusPettersson98

mullvad-relay-selector/src/relay_selector/detailer.rs

@@ -36,8 +36,8 @@ pub enum Error {
     MissingPublicKey,
     #[error("The selected relay does not support IPv6")]
     NoIPv6(Box<Relay>),
-    #[error("Failed to select port")]
-    PortSelectionError,
+    #[error("Failed to select port ({port})")]
+    PortSelectionError { port: Constraint<u16> },
 }
 
 /// Constructs a [`MullvadWireguardEndpoint`] with details for how to connect to a Wireguard relay.
@@ -189,15 +189,16 @@ fn get_port_for_wireguard_relay(
     //
     // TODO: Enable the same behaviour on Android sometime later. For now, keep the old behaviour.
     // If only || was supported in if-let-chains ..
-    let desired_port = if cfg!(target_os = "android") {
+    let port = if cfg!(target_os = "android") {
         query.port
     } else if let ObfuscationQuery::Port = query.obfuscation {
         query.port
     } else {
         Constraint::Any
     };
-    super::helpers::desired_or_random_port_from_range(&data.port_ranges, desired_port)
-        .map_err(|_err| Error::PortSelectionError)
+
+    super::helpers::desired_or_random_port_from_range(&data.port_ranges, port)
+        .map_err(|_err| Error::PortSelectionError { port })
 }
 
 /// Read the [`PublicKey`] of a relay. This will only succeed if [relay][`Relay`] is a

mullvad-relay-selector/src/relay_selector/helpers.rs

@@ -274,9 +274,10 @@ pub fn desired_or_random_port_from_range<R: RangeBounds<u16> + Iterator<Item = u
     port_ranges: &[R],
     desired_port: Constraint<u16>,
 ) -> Result<u16, Error> {
-    desired_port
-        .map(|port| port_if_in_range(port_ranges, port))
-        .unwrap_or_else(|| select_random_port(port_ranges))
+    match desired_port {
+        Constraint::Only(port) => port_if_in_range(port_ranges, port),
+        Constraint::Any => select_random_port(port_ranges),
+    }
 }
 
 /// Return `Ok(port)`, if and only if `port` is in `port_ranges`. Otherwise, return an error.