Add iOS client implementation with SoftEther protocol handshake support

SoftEtherVPN-iOS/SoftEtherVPN-iOS/Protocol/SoftEtherProtocol.swift

@@ -0,0 +1,184 @@
+import Foundation
+import Network
+import Security
+import CryptoKit
+
+/// SoftEtherProtocol manages the communication between iOS client and SoftEther VPN server
+class SoftEtherProtocol {
+    
+    // MARK: - Properties
+    
+    private var secureConnection: SecureConnection?
+    private var isConnected = false
+    private var host: String = ""
+    private var port: UInt16 = 443
+    private var nextPacketId: UInt32 = 1
+    
+    // MARK: - Public Methods
+    
+    /// Connect to a SoftEther VPN server
+    /// - Parameters:
+    ///   - host: The server hostname or IP address
+    ///   - port: The server port (default: 443)
+    ///   - completion: Callback with connection result
+    public func connect(to host: String, port: UInt16 = 443, completion: @escaping (Bool, Error?) -> Void) {
+        self.host = host
+        self.port = port
+        
+        // Create a secure connection
+        secureConnection = SecureConnection(host: host, port: port)
+        
+        // Connect using TLS
+        secureConnection?.connect { [weak self] success, error in
+            guard let self = self, success else {
+                completion(false, error ?? NSError(domain: "SoftEtherError", code: 1, userInfo: [NSLocalizedDescriptionKey: "TLS connection failed"]))
+                return
+            }
+            
+            // After successful TLS connection, send the client signature
+            self.sendClientSignature { success, error in
+                if success {
+                    self.isConnected = true
+                }
+                completion(success, error)
+            }
+        }
+    }
+    
+    /// Disconnect from the server
+    public func disconnect() {
+        secureConnection?.disconnect()
+        isConnected = false
+    }
+    
+    // MARK: - Private Methods
+    
+    /// Send the SoftEther client signature to identify as a legitimate client
+    /// - Parameter completion: Callback with result
+    private func sendClientSignature(completion: @escaping (Bool, Error?) -> Void) {
+        // Generate client signature using our specialized class
+        let signatureData = SoftEtherClientSignature.generateSignature()
+        
+        // Create a packet with the signature data
+        let packetId = self.nextPacketId
+        self.nextPacketId += 1
+        
+        let packet = SoftEtherPacket(type: 0x01, id: packetId, data: signatureData)
+        let packetData = packet.serialize()
+        
+        print("Sending client signature packet: \(packetData.count) bytes")
+        
+        // Send the packet
+        secureConnection?.send(data: packetData) { [weak self] error in
+            guard let self = self else { return }
+            
+            if let error = error {
+                print("Error sending client signature: \(error)")
+                completion(false, error)
+                return
+            }
+            
+            // After sending signature, wait for server response
+            self.receiveServerResponse { success, error in
+                completion(success, error)
+            }
+        }
+    }
+    
+    /// Receive and process server response after sending signature
+    /// - Parameter completion: Callback with result
+    private func receiveServerResponse(completion: @escaping (Bool, Error?) -> Void) {
+        secureConnection?.receive { data, error in
+            if let error = error {
+                print("Error receiving server response: \(error)")
+                completion(false, error)
+                return
+            }
+            
+            guard let data = data, data.count > 4 else {
+                let error = NSError(domain: "SoftEtherError", code: 2, userInfo: [NSLocalizedDescriptionKey: "Invalid server response"])
+                print("Invalid server response: insufficient data")
+                completion(false, error)
+                return
+            }
+            
+            print("Received server response: \(data.count) bytes")
+            
+            // Parse the response packet
+            guard let packet = SoftEtherPacket(fromData: data) else {
+                let error = NSError(domain: "SoftEtherError", code: 3, userInfo: [NSLocalizedDescriptionKey: "Invalid packet format"])
+                print("Could not parse server response packet")
+                completion(false, error)
+                return
+            }
+            
+            // Verify the response
+            let packetData = packet.getData()
+            let isValid = SoftEtherClientSignature.verifyServerResponse(packetData)
+            
+            if isValid {
+                print("Server accepted our client signature")
+                completion(true, nil)
+            } else {
+                print("Server rejected our client signature")
+                let error = NSError(domain: "SoftEtherError", code: 4, userInfo: [NSLocalizedDescriptionKey: "Server rejected client signature"])
+                completion(false, error)
+            }
+        }
+    }
+    
+    /// Send a data packet to the server
+    /// - Parameters:
+    ///   - data: Data to send
+    ///   - completion: Callback with result
+    func sendData(data: Data, completion: @escaping (Bool, Error?) -> Void) {
+        guard isConnected else {
+            completion(false, NSError(domain: "SoftEtherError", code: 5, userInfo: [NSLocalizedDescriptionKey: "Not connected to server"]))
+            return
+        }
+        
+        let packetId = self.nextPacketId
+        self.nextPacketId += 1
+        
+        let packet = SoftEtherPacket(type: 0x05, id: packetId, data: data)
+        let packetData = packet.serialize()
+        
+        secureConnection?.send(data: packetData) { error in
+            if let error = error {
+                completion(false, error)
+                return
+            }
+            
+            completion(true, nil)
+        }
+    }
+    
+    /// Receive data from the server
+    /// - Parameter completion: Callback with received data and result
+    func receiveData(completion: @escaping (Data?, Bool, Error?) -> Void) {
+        guard isConnected else {
+            completion(nil, false, NSError(domain: "SoftEtherError", code: 5, userInfo: [NSLocalizedDescriptionKey: "Not connected to server"]))
+            return
+        }
+        
+        secureConnection?.receive { data, error in
+            if let error = error {
+                completion(nil, false, error)
+                return
+            }
+            
+            guard let data = data, data.count > 4 else {
+                completion(nil, false, NSError(domain: "SoftEtherError", code: 2, userInfo: [NSLocalizedDescriptionKey: "Invalid server response"]))
+                return
+            }
+            
+            // Parse the packet
+            guard let packet = SoftEtherPacket(fromData: data) else {
+                completion(nil, false, NSError(domain: "SoftEtherError", code: 3, userInfo: [NSLocalizedDescriptionKey: "Invalid packet format"]))
+                return
+            }
+            
+            completion(packet.getData(), true, nil)
+        }
+    }
+}