Fix bug where relay selector evaluates only first location constraint when a custom list is selected

Author: Jon Petersson

ios/MullvadREST/Relay/RelaySelector.swift

@@ -136,7 +136,7 @@ public enum RelaySelector {
     }
 
     /// Produce a list of `RelayWithLocation` items satisfying the given constraints
-    private static func applyConstraints<T: AnyRelay>(
+    static func applyConstraints<T: AnyRelay>(
         _ constraints: RelayConstraints,
         relays: [RelayWithLocation<T>]
     ) -> [RelayWithLocation<T>] {
@@ -154,24 +154,10 @@ public enum RelaySelector {
             case .any:
                 return true
             case let .only(relayConstraint):
-                for location in relayConstraint.locations {
-                    switch location {
-                    case let .country(countryCode):
-                        return relayWithLocation.serverLocation.countryCode == countryCode &&
-                            relayWithLocation.relay.includeInCountry
-
-                    case let .city(countryCode, cityCode):
-                        return relayWithLocation.serverLocation.countryCode == countryCode &&
-                            relayWithLocation.serverLocation.cityCode == cityCode
-
-                    case let .hostname(countryCode, cityCode, hostname):
-                        return relayWithLocation.serverLocation.countryCode == countryCode &&
-                            relayWithLocation.serverLocation.cityCode == cityCode &&
-                            relayWithLocation.relay.hostname == hostname
-                    }
+                // At least one location must match the relay under test.
+                return relayConstraint.locations.contains { location in
+                    relayWithLocation.matches(location: location)
                 }
-
-                return false
             }
         }.filter { relayWithLocation -> Bool in
             relayWithLocation.relay.active
@@ -310,9 +296,26 @@ public struct RelaySelectorResult: Codable, Equatable {
     public var location: Location
 }
 
-private struct RelayWithLocation<T: AnyRelay> {
+struct RelayWithLocation<T: AnyRelay> {
     let relay: T
     let serverLocation: Location
+
+    func matches(location: RelayLocation) -> Bool {
+        switch location {
+        case let .country(countryCode):
+            serverLocation.countryCode == countryCode &&
+                relay.includeInCountry
+
+        case let .city(countryCode, cityCode):
+            serverLocation.countryCode == countryCode &&
+                serverLocation.cityCode == cityCode
+
+        case let .hostname(countryCode, cityCode, hostname):
+            serverLocation.countryCode == countryCode &&
+                serverLocation.cityCode == cityCode &&
+                relay.hostname == hostname
+        }
+    }
 }
 
 private struct RelayWithDistance<T: AnyRelay> {

ios/MullvadVPNTests/RelaySelectorTests.swift

@@ -59,6 +59,45 @@ class RelaySelectorTests: XCTestCase {
         XCTAssertEqual(result.relay.hostname, "se6-wireguard")
     }
 
+    func testMultipleLocationsConstraint() throws {
+        let constraints = RelayConstraints(
+            locations: .only(RelayLocations(locations: [
+                .city("se", "got"),
+                .hostname("se", "sto", "se6-wireguard"),
+            ]))
+        )
+
+        let relayWithLocations = sampleRelays.wireguard.relays.map {
+            let location = sampleRelays.locations[$0.location]!
+            let locationComponents = $0.location.split(separator: "-")
+
+            return RelayWithLocation(
+                relay: $0,
+                serverLocation: Location(
+                    country: location.country,
+                    countryCode: String(locationComponents[0]),
+                    city: location.city,
+                    cityCode: String(locationComponents[1]),
+                    latitude: location.latitude,
+                    longitude: location.longitude
+                )
+            )
+        }
+
+        let constrainedLocations = RelaySelector.applyConstraints(constraints, relays: relayWithLocations)
+
+        XCTAssertTrue(
+            constrainedLocations.contains(
+                where: { $0.matches(location: .city("se", "got")) }
+            )
+        )
+        XCTAssertTrue(
+            constrainedLocations.contains(
+                where: { $0.matches(location: .hostname("se", "sto", "se6-wireguard")) }
+            )
+        )
+    }
+
     func testSpecificPortConstraint() throws {
         let constraints = RelayConstraints(
             locations: .only(RelayLocations(locations: [.hostname("se", "sto", "se6-wireguard")])),

ios/MullvadVPNTests/ServerRelaysResponse+Stubs.swift

@@ -63,6 +63,12 @@ enum ServerRelaysResponseStubs {
                 latitude: 32.89748,
                 longitude: -97.040443
             ),
+            "us-nyc": REST.ServerLocation(
+                country: "USA",
+                city: "New York, NY",
+                latitude: 40.6963302,
+                longitude: -74.6034843
+            ),
         ],
         wireguard: REST.ServerWireguardTunnels(
             ipv4Gateway: .loopback,