feat: expose getServerLocations FFI for pro user location picker

android/app/src/main/kotlin/org/getlantern/lantern/handler/MethodHandler.kt

@@ -96,6 +96,8 @@ enum class Methods(val method: String) {
 
     //custom/lantern servers
     GetLanternAvailableServers("getLanternAvailableServers"),
+    GetServerLocations("getServerLocations"),
+    SetPreferredServerLocation("setPreferredServerLocation"),
     GetAutoServerLocation("getAutoServerLocation"),
 
     //Split Tunnel methods
@@ -1090,6 +1092,42 @@ class MethodHandler : FlutterPlugin,
                 }
             }
 
+            Methods.GetServerLocations.method -> {
+                scope.launch {
+                    result.runCatching {
+                        val data = Mobile.getServerLocations()
+                        withContext(Dispatchers.Main) {
+                            success(String(data))
+                        }
+                    }.onFailure { e ->
+                        result.error(
+                            "GetServerLocations",
+                            e.localizedMessage ?: "Error while fetching server locations",
+                            e
+                        )
+                    }
+                }
+            }
+
+            Methods.SetPreferredServerLocation.method -> {
+                scope.launch {
+                    result.runCatching {
+                        val country = call.argument<String>("country") ?: ""
+                        val city = call.argument<String>("city") ?: ""
+                        Mobile.setPreferredServerLocation(country, city)
+                        withContext(Dispatchers.Main) {
+                            success("ok")
+                        }
+                    }.onFailure { e ->
+                        result.error(
+                            "SetPreferredServerLocation",
+                            e.localizedMessage ?: "Error setting preferred server location",
+                            e
+                        )
+                    }
+                }
+            }
+
             Methods.GetAutoServerLocation.method -> {
                 scope.launch {
                     result.runCatching {

assets/locales/en.po

@@ -120,6 +120,9 @@ msgstr "Server Selection"
 msgid "smart_location"
 msgstr "Smart Location"
 
+msgid "smart_protocol"
+msgstr "Smart Protocol"
+
 msgid "automatically_chooses_fastest_location"
 msgstr "Automatically chooses fastest location"
 

go.mod

@@ -25,7 +25,7 @@ require (
 	github.com/alecthomas/assert/v2 v2.3.0
 	github.com/getlantern/common v1.2.1-0.20260224184656-5aefb9c21c85
 	github.com/getlantern/lantern-server-provisioner v0.0.0-20251031121934-8ea031fccfa9
-	github.com/getlantern/radiance v0.0.0-20260324185216-5d134509713d
+	github.com/getlantern/radiance v0.0.0-20260326115814-5a920585cff5
 	github.com/sagernet/sing-box v1.12.22
 	golang.org/x/mobile v0.0.0-20250711185624-d5bb5ecc55c0
 	golang.org/x/sys v0.41.0

go.sum

@@ -261,6 +261,8 @@ github.com/getlantern/pluriconfig v0.0.0-20251126214241-8cc8bc561535 h1:rtDmW8YL
 github.com/getlantern/pluriconfig v0.0.0-20251126214241-8cc8bc561535/go.mod h1:WKJEdjMOD4IuTRYwjQHjT4bmqDl5J82RShMLxPAvi0Q=
 github.com/getlantern/radiance v0.0.0-20260324185216-5d134509713d h1:Pf0CW29vHudf3JHCmFh8A76HXZcJUGyNgBlul1MdyBI=
 github.com/getlantern/radiance v0.0.0-20260324185216-5d134509713d/go.mod h1:bqqrKshKfTPIEOjsedL9p1N5bZBRYTZ2UeUZMtgFWWY=
+github.com/getlantern/radiance v0.0.0-20260326115814-5a920585cff5 h1:me5arg7rAtLgwcGSrS592dgdVlxGPGI+NsMr0K5mss4=
+github.com/getlantern/radiance v0.0.0-20260326115814-5a920585cff5/go.mod h1:bqqrKshKfTPIEOjsedL9p1N5bZBRYTZ2UeUZMtgFWWY=
 github.com/getlantern/samizdat v0.0.3-0.20260310125445-325cf1bd1b60 h1:m9eXjDK9vllbVH467+QXbrxUFFM9Yp7YJ90wZLw4dwU=
 github.com/getlantern/samizdat v0.0.3-0.20260310125445-325cf1bd1b60/go.mod h1:uEeykQSW2/6rTjfPlj3MTTo59poSHXfAHTGgzYDkbr0=
 github.com/getlantern/sing v0.7.18-lantern h1:QKGgIUA3LwmKYP/7JlQTRkxj9jnP4cX2Q/B+nd8XEjo=

ios/Runner/Handlers/MethodHandler.swift

@@ -201,6 +201,18 @@ class MethodHandler {
       case "getLanternAvailableServers":
         self.getLanternAvailableServers(result: result)
 
+      case "getServerLocations":
+        self.getServerLocations(result: result)
+
+      case "setPreferredServerLocation":
+        if let args = call.arguments as? [String: Any] {
+          let country = args["country"] as? String ?? ""
+          let city = args["city"] as? String ?? ""
+          self.setPreferredServerLocation(result: result, country: country, city: city)
+        } else {
+          result(FlutterError(code: "INVALID_ARGS", message: "Missing country/city", details: nil))
+        }
+
       case "getAutoServerLocation":
         self.getAutoServerLocation(result: result)
 
@@ -944,6 +956,36 @@ class MethodHandler {
     }
   }
 
+  func getServerLocations(result: @escaping FlutterResult) {
+    Task {
+      var error: NSError?
+      let locations = MobileGetServerLocations(&error)
+      if let error {
+        await self.handleFlutterError(error, result: result, code: "GET_SERVER_LOCATIONS_ERROR")
+        return
+      }
+      guard let locations else {
+        await MainActor.run { result("[]") }
+        return
+      }
+      await MainActor.run {
+        result(String(data: locations, encoding: .utf8))
+      }
+    }
+  }
+
+  func setPreferredServerLocation(result: @escaping FlutterResult, country: String, city: String) {
+    Task {
+      var error: NSError?
+      MobileSetPreferredServerLocation(country, city, &error)
+      if let error {
+        await self.handleFlutterError(error, result: result, code: "SET_PREFERRED_LOCATION_ERROR")
+        return
+      }
+      await MainActor.run { result("ok") }
+    }
+  }
+
   func getAutoServerLocation(result: @escaping FlutterResult) {
     Task {
       var error: NSError?

lantern-core/core.go

@@ -59,6 +59,9 @@ type App interface {
 	IsRadianceConnected() bool
 	IsVPNRunning() (bool, error)
 	GetAvailableServers() []byte
+	GetServerLocations() ([]byte, error)
+	GetAllLocations() ([]byte, error)
+	SetPreferredServerLocation(country, city string)
 	MyDeviceId() string
 	GetServerByTagJSON(tag string) ([]byte, bool, error)
 	ReferralAttachment(referralCode string) (bool, error)
@@ -406,6 +409,44 @@ func (lc *LanternCore) GetAvailableServers() []byte {
 	return jsonBytes
 }
 
+// GetServerLocations returns the list of all available server locations from
+// the config response. Unlike GetAvailableServers (which returns active
+// outbounds), this returns every location the user can select — including
+// ones that don't have routes yet (the server will provision them on demand
+// when the user selects the location via SetPreferredServer).
+func (lc *LanternCore) GetServerLocations() ([]byte, error) {
+	locations, err := lc.rad.ServerLocations()
+	if err != nil {
+		return nil, fmt.Errorf("getting server locations: %w", err)
+	}
+	data, err := json.Marshal(locations)
+	if err != nil {
+		return nil, fmt.Errorf("marshalling server locations: %w", err)
+	}
+	return data, nil
+}
+
+// GetAllLocations returns a unified list of all server locations, combining
+// available locations from the config response with active outbound details.
+// Each location indicates whether it's active and its protocol.
+func (lc *LanternCore) GetAllLocations() ([]byte, error) {
+	locations, err := lc.rad.AllLocations()
+	if err != nil {
+		return nil, fmt.Errorf("getting all locations: %w", err)
+	}
+	data, err := json.Marshal(locations)
+	if err != nil {
+		return nil, fmt.Errorf("marshalling all locations: %w", err)
+	}
+	return data, nil
+}
+
+// SetPreferredServerLocation sets the preferred server location. The next config
+// fetch will include routes for this region. Pass empty strings to reset to auto.
+func (lc *LanternCore) SetPreferredServerLocation(country, city string) {
+	lc.rad.SetPreferredServer(context.Background(), country, city)
+}
+
 // LoadInstalledApps fetches the app list or rescans if needed using common macOS locations
 // currently only works on/enabled for macOS
 func (lc *LanternCore) LoadInstalledApps(dataDir string) (string, error) {

lantern-core/ffi/ffi.go

@@ -31,9 +31,13 @@ import (
 // by the GC heap bitmap. Allocating Go pointers (like C.CString or base64
 // encoding) on that stack triggers bulkBarrierPreWrite panics.
 func runOnGoStack(fn func() *C.char) *C.char {
-	result, _ := common.RunOffCgoStack(func() (*C.char, error) {
+	result, err := common.RunOffCgoStack(func() (*C.char, error) {
 		return fn(), nil
 	})
+	if err != nil {
+		slog.Error("RunOffCgoStack failed", "error", err)
+		return SendError(err)
+	}
 	return result
 }
 
@@ -290,30 +294,6 @@ func getAutoLocation() *C.char {
 	return C.CString(string(jsonBytes))
 }
 
-// isTagAvailable checks if a server with the given tag exists in the server list.
-// Returns "true" if found, "false" if not found, or "true" when the check cannot be
-// performed (fail-open: allows connection attempts to proceed normally).
-//
-//export isTagAvailable
-func isTagAvailable(_tag *C.char) *C.char {
-	tag := C.GoString(_tag)
-	c, errStr := requireCore()
-	if errStr != nil {
-		slog.Warn("Unable to check tag availability (core not ready), assuming available", "tag", tag)
-		C.free(unsafe.Pointer(errStr))
-		return C.CString("true")
-	}
-	_, found, err := c.GetServerByTagJSON(tag)
-	if err != nil {
-		slog.Warn("Error checking tag availability, assuming available", "tag", tag, "error", err)
-		return C.CString("true")
-	}
-	if found {
-		return C.CString("true")
-	}
-	return C.CString("false")
-}
-
 // startAutoLocationListener starts the auto location listener.
 //
 //export startAutoLocationListener
@@ -349,6 +329,35 @@ func getAvailableServers() *C.char {
 	return C.CString(string(c.GetAvailableServers()))
 }
 
+//export setPreferredServerLocation
+func setPreferredServerLocation(_country, _city *C.char) {
+	country, city := C.GoString(_country), C.GoString(_city)
+	c, errStr := requireCore()
+	if errStr != nil {
+		return
+	}
+	c.SetPreferredServerLocation(country, city)
+}
+
+//export getServerLocations
+func getServerLocations() *C.char {
+	return runOnGoStack(func() *C.char {
+		c, errStr := requireCore()
+		if errStr != nil {
+			return errStr
+		}
+		data, err := c.GetAllLocations()
+		if err != nil {
+			// Fall back to old method if AllLocations not available
+			data, err = c.GetServerLocations()
+			if err != nil {
+				return SendError(err)
+			}
+		}
+		return C.CString(string(data))
+	})
+}
+
 func sendStatusToPort(status VPNStatus) {
 	slog.Debug("sendStatusToPort called", "status", status)
 	if statusPort == 0 {
@@ -493,8 +502,8 @@ func oauthLoginUrl(_provider *C.char) *C.char {
 
 //export oAuthLoginCallback
 func oAuthLoginCallback(_oAuthToken *C.char) *C.char {
-	oAuthToken := C.GoString(_oAuthToken)
 	return runOnGoStack(func() *C.char {
+		oAuthToken := C.GoString(_oAuthToken)
 		c, errStr := requireCore()
 		if errStr != nil {
 			return errStr
@@ -513,8 +522,8 @@ func oAuthLoginCallback(_oAuthToken *C.char) *C.char {
 //
 //export login
 func login(_email, _password *C.char) *C.char {
-	email, password := C.GoString(_email), C.GoString(_password)
 	return runOnGoStack(func() *C.char {
+		email, password := C.GoString(_email), C.GoString(_password)
 		c, errStr := requireCore()
 		if errStr != nil {
 			return errStr
@@ -529,8 +538,8 @@ func login(_email, _password *C.char) *C.char {
 
 //export signup
 func signup(_email, _password *C.char) *C.char {
-	email, password := C.GoString(_email), C.GoString(_password)
 	return runOnGoStack(func() *C.char {
+		email, password := C.GoString(_email), C.GoString(_password)
 		c, errStr := requireCore()
 		if errStr != nil {
 			return errStr
@@ -544,8 +553,8 @@ func signup(_email, _password *C.char) *C.char {
 
 //export logout
 func logout(_email *C.char) *C.char {
-	email := C.GoString(_email)
 	return runOnGoStack(func() *C.char {
+		email := C.GoString(_email)
 		c, errStr := requireCore()
 		if errStr != nil {
 			return errStr
@@ -664,8 +673,8 @@ func completeChangeEmail(_newEmail, _password, _code *C.char) *C.char {
 //
 //export deleteAccount
 func deleteAccount(_email, _password *C.char, _isSSO C.int) *C.char {
-	email, password, isSSO := C.GoString(_email), C.GoString(_password), _isSSO != 0
 	return runOnGoStack(func() *C.char {
+		email, password, isSSO := C.GoString(_email), C.GoString(_password), _isSSO != 0
 		c, errStr := requireCore()
 		if errStr != nil {
 			return errStr

lantern-core/mobile/mobile.go

@@ -237,6 +237,25 @@ func GetAvailableServers() ([]byte, error) {
 	return withCoreR(func(c lanterncore.Core) ([]byte, error) { return c.GetAvailableServers(), nil })
 }
 
+// GetServerLocations returns a unified list of all server locations with active status.
+func GetServerLocations() ([]byte, error) {
+	return withCoreR(func(c lanterncore.Core) ([]byte, error) {
+		data, err := c.GetAllLocations()
+		if err != nil {
+			return c.GetServerLocations()
+		}
+		return data, nil
+	})
+}
+
+// SetPreferredServerLocation sets the preferred server location for the next config fetch.
+func SetPreferredServerLocation(country, city string) error {
+	return withCore(func(c lanterncore.Core) error {
+		c.SetPreferredServerLocation(country, city)
+		return nil
+	})
+}
+
 func IsVPNConnected() bool {
 	return vpn_tunnel.IsVPNRunning()
 }