Add authentication for remote

Sources/App/API/Data+Extensions.swift

@@ -0,0 +1,59 @@
+import Foundation
+
+extension Data {
+
+    public var hexEncoded: String {
+        return map { String(format: "%02hhx", $0) }.joined()
+    }
+
+    // Convert 0 ... 9, a ... f, A ...F to their decimal value,
+    // return nil for all other input characters
+    private func decodeNibble(_ u: UInt16) -> UInt8? {
+        switch(u) {
+        case 0x30 ... 0x39:
+            return UInt8(u - 0x30)
+        case 0x41 ... 0x46:
+            return UInt8(u - 0x41 + 10)
+        case 0x61 ... 0x66:
+            return UInt8(u - 0x61 + 10)
+        default:
+            return nil
+        }
+    }
+
+    public init?(fromHexEncodedString string: String) {
+        let utf16 = string.utf16
+        self.init(capacity: utf16.count/2)
+
+        var i = utf16.startIndex
+        guard utf16.count % 2 == 0 else {
+            return nil
+        }
+        while i != utf16.endIndex {
+            guard let hi = decodeNibble(utf16[i]),
+                let lo = decodeNibble(utf16[utf16.index(i, offsetBy: 1, limitedBy: utf16.endIndex)!]) else {
+                    return nil
+            }
+            var value = hi << 4 + lo
+            self.append(&value, count: 1)
+            i = utf16.index(i, offsetBy: 2, limitedBy: utf16.endIndex)!
+        }
+    }
+}
+
+extension Data {
+
+
+    func convert<T>(into value: T) -> T {
+        withUnsafeBytes {
+            $0.baseAddress!.load(as: T.self)
+        }
+    }
+
+    init<T>(from value: T) {
+        var target = value
+        self = Swift.withUnsafeBytes(of: &target) {
+            Data($0)
+        }
+    }
+}

Sources/App/API/DeviceResponse.swift

@@ -16,6 +16,11 @@ struct DeviceResponse {
         .init(event: .deviceNotConnected)
     }
 
+    /// Shorthand property for a connected event.
+    static var deviceConnected: DeviceResponse {
+        .init(event: .deviceConnected)
+    }
+
     /// Shorthand property for an unexpected socket event.
     static var unexpectedSocketEvent: DeviceResponse {
         .init(event: .unexpectedSocketEvent)

Sources/App/API/Message+Extensions.swift

@@ -1,38 +0,0 @@
-import Foundation
-
-#if canImport(CryptoKit)
-import CryptoKit
-#else
-import Crypto
-#endif
-
-extension Message {
-
-    static var length: Int {
-        SHA256.byteCount + Content.length
-    }
-
-    init<T: Sequence>(decodeFrom data: T) where T.Element == UInt8 {
-        let count = SHA256.byteCount
-        self.mac = Data(data.prefix(count))
-        self.content = .init(decodeFrom: Array(data.dropFirst(count)))
-    }
-
-    func isValid(using key: SymmetricKey) -> Bool {
-         HMAC<SHA256>.isValidAuthenticationCode(mac, authenticating: content.encoded, using: key)
-    }
-}
-
-extension Message.Content {
-
-    func authenticate(using key: SymmetricKey) -> Message {
-        let mac = HMAC<SHA256>.authenticationCode(for: encoded, using: key)
-        return .init(mac: Data(mac.map { $0 }), content: self)
-    }
-
-    func authenticateAndSerialize(using key: SymmetricKey) -> Data {
-        let encoded = self.encoded
-        let mac = HMAC<SHA256>.authenticationCode(for: encoded, using: key)
-        return Data(mac.map { $0 }) + encoded
-    }
-}

Sources/App/API/Message.swift

@@ -1,11 +1,36 @@
 import Foundation
 import NIOCore
 
+#if canImport(CryptoKit)
+import CryptoKit
+#else
+import Crypto
+#endif
+
 /**
  An authenticated message to or from the device.
  */
 struct Message: Equatable, Hashable {
 
+    /// The message authentication code for the message (32 bytes)
+    let mac: Data
+
+    /// The message content
+    let content: Content
+
+    /**
+     Create an authenticated message
+     - Parameter mac: The message authentication code
+     - Parameter content: The message content
+     */
+    init(mac: Data, content: Content) {
+        self.mac = mac
+        self.content = content
+    }
+}
+
+extension Message {
+
     /**
      The message content without authentication.
      */
@@ -30,13 +55,13 @@ struct Message: Equatable, Hashable {
         /**
          Decode message content from data.
 
-         The data consists of two `UInt32` encoded in big endian format (MSB at index 0)
+         The data consists of two `UInt32` encoded in little endian format
          - Warning: The sequence must contain at least 8 bytes, or the function will crash.
          - Parameter data: The sequence containing the bytes.
          */
         init<T: Sequence>(decodeFrom data: T) where T.Element == UInt8 {
-            self.time = UInt32(data: data.prefix(MemoryLayout<UInt32>.size))
-            self.id = UInt32(data: data.dropFirst(MemoryLayout<UInt32>.size))
+            self.time = UInt32(data: Data(data.prefix(MemoryLayout<UInt32>.size)))
+            self.id = UInt32(data: Data(data.dropFirst(MemoryLayout<UInt32>.size)))
         }
 
         /// The byte length of an encoded message content
@@ -48,27 +73,15 @@ struct Message: Equatable, Hashable {
         var encoded: Data {
             time.encoded + id.encoded
         }
-
-        /// The message content encoded to bytes
-        var bytes: [UInt8] {
-            time.bytes + id.bytes
-        }
     }
 
-    /// The message authentication code for the message (32 bytes)
-    let mac: Data
+}
 
-    /// The message content
-    let content: Content
+extension Message {
 
-    /**
-     Create an authenticated message
-     - Parameter mac: The message authentication code
-     - Parameter content: The message content
-     */
-    init(mac: Data, content: Content) {
-        self.mac = mac
-        self.content = content
+    /// The length of a message in bytes
+    static var length: Int {
+        SHA256.byteCount + Content.length
     }
 
     /**
@@ -88,35 +101,51 @@ struct Message: Equatable, Hashable {
         mac + content.encoded
     }
 
-    /// The message encoded to bytes
     var bytes: [UInt8] {
-        Array(mac) + content.bytes
+        Array(encoded)
+    }
+
+    /**
+     Create a message from received bytes.
+     - Parameter data: The sequence of bytes
+     - Note: The sequence must contain at least `Message.length` bytes, or the function will crash.
+     */
+    init<T: Sequence>(decodeFrom data: T) where T.Element == UInt8 {
+        let count = SHA256.byteCount
+        self.mac = Data(data.prefix(count))
+        self.content = .init(decodeFrom: Array(data.dropFirst(count)))
+    }
+
+    /**
+     Check if the message contains a valid authentication code
+     - Parameter key: The key used to sign the message.
+     - Returns: `true`, if the message is valid.
+     */
+    func isValid(using key: SymmetricKey) -> Bool {
+         HMAC<SHA256>.isValidAuthenticationCode(mac, authenticating: content.encoded, using: key)
     }
 }
 
- extension UInt32 {
+extension Message.Content {
 
-     /**
-      Create a value from a big-endian data representation (MSB first)
-      - Note: The data must contain exactly four bytes.
-      */
-     init<T: Sequence>(data: T) where T.Element == UInt8 {
-        self = data
-            .reversed()
-            .enumerated()
-            .map { UInt32($0.element) << ($0.offset * 8) }
-            .reduce(0, +)
-     }
+    /**
+     Calculate an authentication code for the message content.
+     - Parameter key: The key to use to sign the content.
+     - Returns: The new message signed with the key.
+     */
+    func authenticate(using key: SymmetricKey) -> Message {
+        let mac = HMAC<SHA256>.authenticationCode(for: encoded, using: key)
+        return .init(mac: Data(mac.map { $0 }), content: self)
+    }
 
-     /// The value encoded to a big-endian representation
-     var encoded: Data {
-         .init(bytes)
-     }
-
-     /// The value encoded to a big-endian byte array
-     var bytes: [UInt8] {
-         (0..<4).reversed().map {
-             UInt8((self >> ($0*8)) & 0xFF)
-         }
-     }
+    /**
+     Calculate an authentication code for the message content and convert everything to data.
+     - Parameter key: The key to use to sign the content.
+     - Returns: The new message signed with the key, serialized to bytes.
+     */
+    func authenticateAndSerialize(using key: SymmetricKey) -> Data {
+        let encoded = self.encoded
+        let mac = HMAC<SHA256>.authenticationCode(for: encoded, using: key)
+        return Data(mac.map { $0 }) + encoded
+    }
 }

Sources/App/API/MessageResult.swift

@@ -38,6 +38,9 @@ enum MessageResult: UInt8 {
 
     /// Another message is being processed by the device
     case operationInProgress = 14
+
+    /// The device is connected
+    case deviceConnected = 15
 }
 
 extension MessageResult: CustomStringConvertible {
@@ -66,6 +69,8 @@ extension MessageResult: CustomStringConvertible {
             return "The device did not respond"
         case .operationInProgress:
             return "Another operation is in progress"
+        case .deviceConnected:
+            return "The device is connected"
         }
     }
 }

Sources/App/API/ServerMessage.swift

@@ -0,0 +1,46 @@
+import Foundation
+import NIOCore
+
+#if canImport(CryptoKit)
+import CryptoKit
+#else
+import Crypto
+#endif
+
+struct ServerMessage {
+
+    static let authTokenSize = SHA256.byteCount
+
+    static let length = authTokenSize + Message.length
+
+    let authToken: Data
+
+    let message: Message
+
+    /**
+     Decode a message from a byte buffer.
+     The buffer must contain at least `ServerMessage.length` bytes, or it will return `nil`.
+     - Parameter buffer: The buffer containing the bytes.
+     */
+    init?(decodeFrom buffer: ByteBuffer) {
+        guard let data = buffer.getBytes(at: 0, length: ServerMessage.length) else {
+            return nil
+        }
+        self.authToken = Data(data.prefix(ServerMessage.authTokenSize))
+        self.message = Message(decodeFrom: Data(data.dropFirst(ServerMessage.length)))
+    }
+
+    var encoded: Data {
+        authToken + message.encoded
+    }
+
+    static func token(from buffer: ByteBuffer) -> Data? {
+        guard buffer.readableBytes == authTokenSize else {
+            return nil
+        }
+        guard let bytes = buffer.getBytes(at: 0, length: authTokenSize) else {
+            return nil
+        }
+        return Data(bytes)
+    }
+}

Sources/App/API/UInt32+Extensions.swift

@@ -0,0 +1,18 @@
+import Foundation
+
+extension UInt32 {
+
+    /**
+     Create a value from a little-endian data representation (MSB first)
+     - Note: The data must contain exactly four bytes.
+     */
+    init(data: Data) {
+        let value = data.convert(into: UInt32.zero)
+        self = CFSwapInt32LittleToHost(value)
+    }
+
+    /// The value encoded to a little-endian representation
+    var encoded: Data {
+        Data(from: CFSwapInt32HostToLittle(self))
+    }
+}