Add shadowsocks obfuscation as an option

ios/MullvadRustRuntime/UDPOverTCPObfuscator.swift → ios/MullvadRustRuntime/TunnelObfuscator.swift

@@ -11,8 +11,13 @@ import MullvadRustRuntimeProxy
 import MullvadTypes
 import Network
 
+public enum TunnelObfuscationProtocol {
+    case udpOverTcp
+    case shadowsocks
+}
+
 public protocol TunnelObfuscation {
-    init(remoteAddress: IPAddress, tcpPort: UInt16)
+    init(remoteAddress: IPAddress, tcpPort: UInt16, obfuscationProtocol: TunnelObfuscationProtocol)
     func start()
     func stop()
     var localUdpPort: UInt16 { get }
@@ -21,11 +26,15 @@ public protocol TunnelObfuscation {
     var transportLayer: TransportLayer { get }
 }
 
-/// Class that implements UDP over TCP obfuscation by accepting traffic on a local UDP port and proxying it over TCP to the remote endpoint.
-public final class UDPOverTCPObfuscator: TunnelObfuscation {
+/// Class that implements obfuscation by accepting traffic on a local port and proxying it to the remote endpoint.
+///
+/// The obfuscation happens either by wrapping UDP traffic into TCP traffic, or by using a local shadowsocks server
+/// to encrypt the UDP traffic sent.
+public final class TunnelObfuscator: TunnelObfuscation {
     private let stateLock = NSLock()
     private let remoteAddress: IPAddress
     internal let tcpPort: UInt16
+    internal let obfuscationProtocol: TunnelObfuscationProtocol
 
     private var proxyHandle = ProxyHandle(context: nil, port: 0)
     private var isStarted = false
@@ -38,12 +47,20 @@ public final class UDPOverTCPObfuscator: TunnelObfuscation {
 
     public var remotePort: UInt16 { tcpPort }
 
-    public var transportLayer: TransportLayer { .tcp }
+    public var transportLayer: TransportLayer {
+        switch obfuscationProtocol {
+        case .udpOverTcp:
+            .tcp
+        case .shadowsocks:
+            .udp
+        }
+    }
 
     /// Initialize tunnel obfuscator with remote server address and TCP port where udp2tcp is running.
-    public init(remoteAddress: IPAddress, tcpPort: UInt16) {
+    public init(remoteAddress: IPAddress, tcpPort: UInt16, obfuscationProtocol: TunnelObfuscationProtocol) {
         self.remoteAddress = remoteAddress
         self.tcpPort = tcpPort
+        self.obfuscationProtocol = obfuscationProtocol
     }
 
     deinit {
@@ -54,13 +71,19 @@ public final class UDPOverTCPObfuscator: TunnelObfuscation {
         stateLock.withLock {
             guard !isStarted else { return }
 
+            let obfuscationProtocol = switch obfuscationProtocol {
+            case .udpOverTcp: TunnelObfuscatorProtocol(0)
+            case .shadowsocks: TunnelObfuscatorProtocol(1)
+            }
+
             let result = withUnsafeMutablePointer(to: &proxyHandle) { proxyHandlePointer in
                 let addressData = remoteAddress.rawValue
 
                 return start_tunnel_obfuscator_proxy(
                     addressData.map { $0 },
                     UInt(addressData.count),
                     tcpPort,
+                    obfuscationProtocol,
                     proxyHandlePointer
                 )
             }

ios/MullvadRustRuntime/include/mullvad_rust_runtime.h

@@ -5,6 +5,15 @@
 #include <stdint.h>
 #include <stdlib.h>
 
+/**
+ * SAFETY: `TunnelObfuscatorProtocol` values must either be `0` or `1`
+ */
+enum TunnelObfuscatorProtocol {
+  UdpOverTcp = 0,
+  Shadowsocks,
+};
+typedef uint8_t TunnelObfuscatorProtocol;
+
 /**
  * A thin wrapper around [`mullvad_encrypted_dns_proxy::state::EncryptedDnsProxyState`] that
  * can start a local forwarder (see [`Self::start`]).
@@ -179,6 +188,7 @@ int32_t stop_shadowsocks_proxy(struct ProxyHandle *proxy_config);
 int32_t start_tunnel_obfuscator_proxy(const uint8_t *peer_address,
                                       uintptr_t peer_address_len,
                                       uint16_t peer_port,
+                                      TunnelObfuscatorProtocol obfuscation_protocol,
                                       struct ProxyHandle *proxy_handle);
 
 int32_t stop_tunnel_obfuscator_proxy(struct ProxyHandle *proxy_handle);

ios/MullvadRustRuntimeTests/TCPConnection.swift

@@ -11,14 +11,16 @@ import Network
 
 /// Minimal implementation of TCP connection capable of receiving data.
 /// > Warning: Do not use this implementation in production code. See the warning in `start()`.
-class TCPConnection {
+class TCPConnection: Connection {
     private let dispatchQueue = DispatchQueue(label: "TCPConnection")
     private let nwConnection: NWConnection
 
-    init(nwConnection: NWConnection) {
+    required init(nwConnection: NWConnection) {
         self.nwConnection = nwConnection
     }
 
+    static var connectionParameters: NWParameters { .tcp }
+
     deinit {
         cancel()
     }

ios/MullvadRustRuntimeTests/TunnelObfuscationTests.swift

@@ -11,16 +11,20 @@ import Network
 import XCTest
 
 final class TunnelObfuscationTests: XCTestCase {
-    func testRunningObfuscatorProxy() async throws {
+    func testRunningUdpOverTcpObfuscatorProxy() async throws {
         // Each packet is prefixed with u16 that contains a payload length.
         let preambleLength = MemoryLayout<UInt16>.size
         let markerData = Data([109, 117, 108, 108, 118, 97, 100])
         let packetLength = markerData.count + preambleLength
 
-        let tcpListener = try TCPUnsafeListener()
+        let tcpListener = try UnsafeListener<TCPConnection>()
         try await tcpListener.start()
 
-        let obfuscator = UDPOverTCPObfuscator(remoteAddress: IPv4Address.loopback, tcpPort: tcpListener.listenPort)
+        let obfuscator = TunnelObfuscator(
+            remoteAddress: IPv4Address.loopback,
+            tcpPort: tcpListener.listenPort,
+            obfuscationProtocol: .udpOverTcp
+        )
         obfuscator.start()
 
         // Accept incoming connections
@@ -46,4 +50,42 @@ final class TunnelObfuscationTests: XCTestCase {
         XCTAssert(receivedData.count == packetLength)
         XCTAssertEqual(receivedData[preambleLength...], markerData)
     }
+
+    func testRunningShadowsocksObfuscatorProxy() async throws {
+        let markerData = Data([109, 117, 108, 108, 118, 97, 100])
+
+        let localUdpListener = try UnsafeListener<UDPConnection>()
+        try await localUdpListener.start()
+
+        let localObfuscator = TunnelObfuscator(
+            remoteAddress: IPv4Address.loopback,
+            tcpPort: localUdpListener.listenPort,
+            obfuscationProtocol: .shadowsocks
+        )
+        localObfuscator.start()
+
+        // Accept incoming connections
+        let localConnectionDataTask = Task {
+            for await obfuscatedConnection in localUdpListener.newConnections {
+                try await obfuscatedConnection.start()
+
+                let readDatagram = try await obfuscatedConnection.readSingleDatagram()
+                // Write into the connection the unencrypted payload that was just read
+                try await obfuscatedConnection.sendData(readDatagram)
+                return readDatagram
+            }
+            throw POSIXError(.ECANCELED)
+        }
+
+        // Send marker data over UDP
+        let connection = UDPConnection(remote: IPv4Address.loopback, port: localObfuscator.localUdpPort)
+        try await connection.start()
+        try await connection.sendData(markerData)
+        let readDataFromObfuscator = try await connection.readSingleDatagram()
+
+        // As the connection data is encrypted and this test does not run a shadowsocks server to decrypt the payload
+        // The connection from the local UDP listener writes back what it read from the obfuscator, unencrypted
+        _ = try await localConnectionDataTask.value
+        XCTAssertEqual(readDataFromObfuscator, markerData)
+    }
 }

ios/MullvadRustRuntimeTests/UDPConnection.swift

@@ -9,20 +9,31 @@
 import Foundation
 import Network
 
+protocol Connection {
+    init(nwConnection: NWConnection)
+    static var connectionParameters: NWParameters { get }
+}
+
 /// Minimal implementation of UDP connection capable of sending data.
 /// > Warning: Do not use this implementation in production code. See the warning in `start()`.
-class UDPConnection {
+class UDPConnection: Connection {
     private let dispatchQueue = DispatchQueue(label: "UDPConnection")
     private let nwConnection: NWConnection
 
-    init(remote: IPAddress, port: UInt16) {
-        nwConnection = NWConnection(
+    convenience init(remote: IPAddress, port: UInt16) {
+        self.init(nwConnection: NWConnection(
             host: NWEndpoint.Host("\(remote)"),
             port: NWEndpoint.Port(integerLiteral: port),
             using: .udp
-        )
+        ))
+    }
+
+    required init(nwConnection: NWConnection) {
+        self.nwConnection = nwConnection
     }
 
+    static var connectionParameters: NWParameters { .udp }
+
     deinit {
         cancel()
     }
@@ -58,6 +69,22 @@ class UDPConnection {
         nwConnection.cancel()
     }
 
+    func readSingleDatagram() async throws -> Data {
+        return try await withCheckedThrowingContinuation { continuation in
+            nwConnection.receiveMessage { data, _, _, error in
+                guard let data else {
+                    continuation.resume(throwing: POSIXError(.EIO))
+                    return
+                }
+                if let error {
+                    continuation.resume(throwing: error)
+                    return
+                }
+                continuation.resume(with: .success(data))
+            }
+        }
+    }
+
     func sendData(_ data: Data) async throws {
         return try await withCheckedThrowingContinuation { continuation in
             nwConnection.send(content: data, completion: .contentProcessed { error in

ios/MullvadRustRuntimeTests/TCPUnsafeListener.swift → ios/MullvadRustRuntimeTests/UnsafeListener.swift

@@ -1,5 +1,5 @@
 //
-//  TCPUnsafeListener.swift
+//  UnsafeListener.swift
 //  MullvadRustRuntimeTests
 //
 //  Created by pronebird on 27/06/2023.
@@ -8,25 +8,24 @@
 
 import Network
 
-/// Minimal implementation of a TCP listener.
 /// > Warning: Do not use this implementation in production code. See the warning in `start()`.
-class TCPUnsafeListener {
-    private let dispatchQueue = DispatchQueue(label: "TCPListener")
+class UnsafeListener<T: Connection> {
+    private let dispatchQueue = DispatchQueue(label: "com.test.unsafeListener")
     private let listener: NWListener
 
-    /// A stream of new TCP connections.
-    /// The caller may iterate over this stream to accept new TCP connections.
+    /// A stream of new connections.
+    /// The caller may iterate over this stream to accept new connections.
     ///
-    /// `TCPConnection` objects are returned unopen, so the caller has to call `TCPConnection.start()` to accept the
+    /// `Connection` objects are returned unopen, so the caller has to call `Connection.start()` to accept the
     /// connection before initiating the data exchange.
-    let newConnections: AsyncStream<TCPConnection>
+    let newConnections: AsyncStream<T>
 
     init() throws {
-        let listener = try NWListener(using: .tcp)
+        let listener = try NWListener(using: T.connectionParameters)
 
         newConnections = AsyncStream { continuation in
             listener.newConnectionHandler = { nwConnection in
-                continuation.yield(TCPConnection(nwConnection: nwConnection))
+                continuation.yield(T(nwConnection: nwConnection))
             }
             continuation.onTermination = { @Sendable _ in
                 listener.newConnectionHandler = nil
@@ -40,7 +39,7 @@ class TCPUnsafeListener {
         cancel()
     }
 
-    /// Local TCP port bound by listener on which it accepts new connections.
+    /// Local port bound by listener on which it accepts new connections.
     var listenPort: UInt16 {
         return listener.port?.rawValue ?? 0
     }

ios/MullvadVPN.xcodeproj/project.pbxproj

@@ -841,10 +841,10 @@
 		A9D99B9A2A1F7C3200DE27D3 /* RESTTransport.swift in Sources */ = {isa = PBXBuildFile; fileRef = 06FAE67D28F83CA50033DD93 /* RESTTransport.swift */; };
 		A9D9A4AE2C36CFE9004088DD /* WireGuardKitTypes in Frameworks */ = {isa = PBXBuildFile; productRef = A9D9A4AD2C36CFE9004088DD /* WireGuardKitTypes */; };
 		A9D9A4B12C36D10E004088DD /* ShadowSocksProxy.swift in Sources */ = {isa = PBXBuildFile; fileRef = F0DDE40F2B220458006B57A7 /* ShadowSocksProxy.swift */; };
-		A9D9A4B22C36D12D004088DD /* UDPOverTCPObfuscator.swift in Sources */ = {isa = PBXBuildFile; fileRef = 584023212A406BF5007B27AC /* UDPOverTCPObfuscator.swift */; };
+		A9D9A4B22C36D12D004088DD /* TunnelObfuscator.swift in Sources */ = {isa = PBXBuildFile; fileRef = 584023212A406BF5007B27AC /* TunnelObfuscator.swift */; };
 		A9D9A4BB2C36D397004088DD /* EphemeralPeerNegotiator.swift in Sources */ = {isa = PBXBuildFile; fileRef = A9EB4F9C2B7FAB21002A2D7A /* EphemeralPeerNegotiator.swift */; };
 		A9D9A4C42C36D53C004088DD /* MullvadRustRuntime.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = A992DA1D2C24709F00DE7CE5 /* MullvadRustRuntime.framework */; };
-		A9D9A4CC2C36D54E004088DD /* TCPUnsafeListener.swift in Sources */ = {isa = PBXBuildFile; fileRef = 585A02E82A4B283000C6CAFF /* TCPUnsafeListener.swift */; };
+		A9D9A4CC2C36D54E004088DD /* UnsafeListener.swift in Sources */ = {isa = PBXBuildFile; fileRef = 585A02E82A4B283000C6CAFF /* UnsafeListener.swift */; };
 		A9D9A4CD2C36D54E004088DD /* UDPConnection.swift in Sources */ = {isa = PBXBuildFile; fileRef = 585A02EA2A4B285800C6CAFF /* UDPConnection.swift */; };
 		A9D9A4CE2C36D54E004088DD /* TunnelObfuscationTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 58695A9F2A4ADA9200328DB3 /* TunnelObfuscationTests.swift */; };
 		A9D9A4CF2C36D54E004088DD /* TCPConnection.swift in Sources */ = {isa = PBXBuildFile; fileRef = 585A02EC2A4B28F300C6CAFF /* TCPConnection.swift */; };
@@ -1506,7 +1506,7 @@
 		583E60952A9F6D0800DC61EF /* ConfigurationBuilder.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ConfigurationBuilder.swift; sourceTree = "<group>"; };
 		583FE00B29C0C7FD006E85F9 /* ModalPresentationConfiguration.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ModalPresentationConfiguration.swift; sourceTree = "<group>"; };
 		583FE01129C0F99A006E85F9 /* PresentationControllerDismissalInterceptor.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = PresentationControllerDismissalInterceptor.swift; sourceTree = "<group>"; };
-		584023212A406BF5007B27AC /* UDPOverTCPObfuscator.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = UDPOverTCPObfuscator.swift; sourceTree = "<group>"; };
+		584023212A406BF5007B27AC /* TunnelObfuscator.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TunnelObfuscator.swift; sourceTree = "<group>"; };
 		584023282A407F5F007B27AC /* libmullvad_ios.a */ = {isa = PBXFileReference; lastKnownFileType = archive.ar; name = libmullvad_ios.a; path = "../target/aarch64-apple-ios/debug/libmullvad_ios.a"; sourceTree = "<group>"; };
 		5840250322B11AB700E4CFEC /* MullvadEndpoint.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MullvadEndpoint.swift; sourceTree = "<group>"; };
 		5840BE34279EDB16002836BA /* OperationError.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = OperationError.swift; sourceTree = "<group>"; };
@@ -1525,7 +1525,7 @@
 		584D26C5270C8741004EA533 /* SettingsDNSTextCell.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SettingsDNSTextCell.swift; sourceTree = "<group>"; };
 		58561C98239A5D1500BD6B5E /* IPv4Endpoint.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = IPv4Endpoint.swift; sourceTree = "<group>"; };
 		5859A55429CD9DD800F66591 /* changes.txt */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text; path = changes.txt; sourceTree = "<group>"; };
-		585A02E82A4B283000C6CAFF /* TCPUnsafeListener.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TCPUnsafeListener.swift; sourceTree = "<group>"; };
+		585A02E82A4B283000C6CAFF /* UnsafeListener.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = UnsafeListener.swift; sourceTree = "<group>"; };
 		585A02EA2A4B285800C6CAFF /* UDPConnection.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = UDPConnection.swift; sourceTree = "<group>"; };
 		585A02EC2A4B28F300C6CAFF /* TCPConnection.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TCPConnection.swift; sourceTree = "<group>"; };
 		585CA70E25F8C44600B47C62 /* UIMetrics.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = UIMetrics.swift; sourceTree = "<group>"; };
@@ -4090,7 +4090,7 @@
 				A948809A2BC9308D0090A44C /* EphemeralPeerExchangeActor.swift */,
 				A9EB4F9C2B7FAB21002A2D7A /* EphemeralPeerNegotiator.swift */,
 				F0DDE40F2B220458006B57A7 /* ShadowSocksProxy.swift */,
-				584023212A406BF5007B27AC /* UDPOverTCPObfuscator.swift */,
+				584023212A406BF5007B27AC /* TunnelObfuscator.swift */,
 				014449942CA293B100C0C2F2 /* EncryptedDNSProxy.swift */,
 			);
 			path = MullvadRustRuntime;
@@ -4099,12 +4099,12 @@
 		A9D9A4C12C36D53C004088DD /* MullvadRustRuntimeTests */ = {
 			isa = PBXGroup;
 			children = (
-				A9C308392C19DDA7008715F1 /* MullvadPostQuantum+Stubs.swift */,
 				A98F1B502C19C48D003C869E /* EphemeralPeerExchangeActorTests.swift */,
+				A9C308392C19DDA7008715F1 /* MullvadPostQuantum+Stubs.swift */,
 				585A02EC2A4B28F300C6CAFF /* TCPConnection.swift */,
-				585A02E82A4B283000C6CAFF /* TCPUnsafeListener.swift */,
 				58695A9F2A4ADA9200328DB3 /* TunnelObfuscationTests.swift */,
 				585A02EA2A4B285800C6CAFF /* UDPConnection.swift */,
+				585A02E82A4B283000C6CAFF /* UnsafeListener.swift */,
 			);
 			path = MullvadRustRuntimeTests;
 			sourceTree = "<group>";
@@ -6233,7 +6233,7 @@
 				A9D9A4B12C36D10E004088DD /* ShadowSocksProxy.swift in Sources */,
 				014449952CA293B100C0C2F2 /* EncryptedDNSProxy.swift in Sources */,
 				A9D9A4BB2C36D397004088DD /* EphemeralPeerNegotiator.swift in Sources */,
-				A9D9A4B22C36D12D004088DD /* UDPOverTCPObfuscator.swift in Sources */,
+				A9D9A4B22C36D12D004088DD /* TunnelObfuscator.swift in Sources */,
 				A9173C322C36CCDD00F6A08C /* PacketTunnelProvider+TCPConnection.swift in Sources */,
 				F05919802C45515200C301F3 /* EphemeralPeerExchangeActor.swift in Sources */,
 			);
@@ -6247,7 +6247,7 @@
 				F08B6B772C52878400D0A121 /* EphemeralPeerExchangeActorTests.swift in Sources */,
 				A9D9A4CF2C36D54E004088DD /* TCPConnection.swift in Sources */,
 				A9D9A4CE2C36D54E004088DD /* TunnelObfuscationTests.swift in Sources */,
-				A9D9A4CC2C36D54E004088DD /* TCPUnsafeListener.swift in Sources */,
+				A9D9A4CC2C36D54E004088DD /* UnsafeListener.swift in Sources */,
 				A9D9A4CD2C36D54E004088DD /* UDPConnection.swift in Sources */,
 				F0A1638A2C47B77300592300 /* ServerRelaysResponse+Stubs.swift in Sources */,
 			);

ios/PacketTunnel/PacketTunnelProvider/PacketTunnelProvider.swift

@@ -97,7 +97,7 @@ class PacketTunnelProvider: NEPacketTunnelProvider {
                 guard let self = self else { return }
                 tunnelSettingsListener.onNewSettings?(settings.tunnelSettings)
             },
-            protocolObfuscator: ProtocolObfuscator<UDPOverTCPObfuscator>()
+            protocolObfuscator: ProtocolObfuscator<TunnelObfuscator>()
         )
 
         let urlRequestProxy = URLRequestProxy(dispatchQueue: internalQueue, transportProvider: transportProvider)

ios/PacketTunnelCore/Actor/ProtocolObfuscator.swift

@@ -51,9 +51,11 @@ public class ProtocolObfuscator<Obfuscator: TunnelObfuscation>: ProtocolObfuscat
             return endpoint
         }
 
+        // At this point, the only possible obfuscation methods should be either `.udpOverTcp` or `.shadowsocks`
         let obfuscator = Obfuscator(
             remoteAddress: endpoint.ipv4Relay.ip,
-            tcpPort: remotePort
+            tcpPort: remotePort,
+            obfuscationProtocol: obfuscationMethod == .shadowsocks ? .shadowsocks : .udpOverTcp
         )
 
         obfuscator.start()

ios/PacketTunnelCoreTests/Mocks/TunnelObfuscationStub.swift

@@ -15,7 +15,7 @@ struct TunnelObfuscationStub: TunnelObfuscation {
     var transportLayer: TransportLayer { .udp }
 
     let remotePort: UInt16
-    init(remoteAddress: IPAddress, tcpPort: UInt16) {
+    init(remoteAddress: IPAddress, tcpPort: UInt16, obfuscationProtocol: TunnelObfuscationProtocol) {
         remotePort = tcpPort
     }