Add iOS client implementation with SoftEther protocol handshake support

SoftEtherVPN-iOS/SoftEtherVPN-iOS/Protocol/SecureConnection.swift

@@ -0,0 +1,118 @@
+import Foundation
+import Network
+import Security
+
+/// SecureConnection handles the TLS connection with the SoftEther VPN server
+class SecureConnection {
+    
+    // MARK: - Properties
+    
+    private var connection: NWConnection?
+    private let host: String
+    private let port: UInt16
+    private let queue = DispatchQueue(label: "com.softether.connection", qos: .userInitiated)
+    
+    // MARK: - Initialization
+    
+    /// Initialize a secure connection
+    /// - Parameters:
+    ///   - host: Server hostname or IP address
+    ///   - port: Server port number
+    init(host: String, port: UInt16) {
+        self.host = host
+        self.port = port
+    }
+    
+    // MARK: - Public Methods
+    
+    /// Connect to the server using TLS
+    /// - Parameter completion: Callback with connection result
+    func connect(completion: @escaping (Bool, Error?) -> Void) {
+        let hostEndpoint = NWEndpoint.Host(host)
+        let portEndpoint = NWEndpoint.Port(rawValue: port)!
+        
+        // Create TLS parameters
+        let tlsOptions = NWProtocolTLS.Options()
+        
+        // Configure TLS for maximum compatibility with SoftEther
+        let securityOptions = tlsOptions.securityProtocolOptions
+        sec_protocol_options_set_tls_min_version(securityOptions, .TLSv12)
+        sec_protocol_options_set_tls_max_version(securityOptions, .TLSv13)
+        
+        // Allow all cipher suites for compatibility
+        sec_protocol_options_set_cipher_suites(securityOptions, nil, 0)
+        
+        // Disable certificate validation for initial development (ENABLE IN PRODUCTION)
+        sec_protocol_options_set_verify_block(securityOptions, { (_, _, trustResult, _) in
+            return true // Accept all certificates for testing
+        }, queue)
+        
+        // Create TCP options with TLS
+        let tcpOptions = NWProtocolTCP.Options()
+        tcpOptions.enableKeepalive = true
+        tcpOptions.keepaliveIdle = 30
+        
+        // Create connection parameters
+        let parameters = NWParameters(tls: tlsOptions, tcp: tcpOptions)
+        
+        // Create the connection
+        connection = NWConnection(host: hostEndpoint, port: portEndpoint, using: parameters)
+        
+        // Set up state handling
+        connection?.stateUpdateHandler = { [weak self] state in
+            switch state {
+            case .ready:
+                completion(true, nil)
+            case .failed(let error):
+                self?.disconnect()
+                completion(false, error)
+            case .cancelled:
+                completion(false, NSError(domain: "SoftEtherError", code: 1000, userInfo: [NSLocalizedDescriptionKey: "Connection cancelled"]))
+            default:
+                break
+            }
+        }
+        
+        // Start the connection
+        connection?.start(queue: queue)
+    }
+    
+    /// Disconnect from the server
+    func disconnect() {
+        connection?.cancel()
+        connection = nil
+    }
+    
+    /// Send data to the server
+    /// - Parameters:
+    ///   - data: Data to send
+    ///   - completion: Callback with error if any
+    func send(data: Data, completion: @escaping (Error?) -> Void) {
+        guard let connection = connection, connection.state == .ready else {
+            completion(NSError(domain: "SoftEtherError", code: 1001, userInfo: [NSLocalizedDescriptionKey: "Connection not ready"]))
+            return
+        }
+        
+        connection.send(content: data, completion: .contentProcessed { error in
+            completion(error)
+        })
+    }
+    
+    /// Receive data from the server
+    /// - Parameter completion: Callback with received data and error if any
+    func receive(completion: @escaping (Data?, Error?) -> Void) {
+        guard let connection = connection, connection.state == .ready else {
+            completion(nil, NSError(domain: "SoftEtherError", code: 1001, userInfo: [NSLocalizedDescriptionKey: "Connection not ready"]))
+            return
+        }
+        
+        connection.receive(minimumIncompleteLength: 1, maximumLength: 65536) { data, _, isComplete, error in
+            completion(data, error)
+            
+            if isComplete {
+                // Connection was closed by the peer
+                self.disconnect()
+            }
+        }
+    }
+}