Getting started

1 files changed, 264 insertions, 0 deletions

diff --git a/Hotline/Network/HotlineTracker.swift b/Hotline/Network/HotlineTracker.swift
new file mode 100644
index 0000000..9b21ab2
--- /dev/null
+++ b/Hotline/Network/HotlineTracker.swift
@@ -0,0 +1,264 @@
+import Foundation
+import Network
+
+struct HotlineServer: Identifiable {
+  var id = UUID()
+  let address: String
+  let port: UInt16
+  let users: UInt16
+  let name: String?
+  let description: String?
+}
+
+enum HotlineTrackerStatus: Int {
+  case disconnected
+  case connecting
+  case connected
+}
+
+class HotlineTracker : ObservableObject {
+  let serverAddress: NWEndpoint.Host
+  let serverPort: NWEndpoint.Port = NWEndpoint.Port(rawValue: 5498)!
+  let callback: ([HotlineServer]) -> Void
+  
+  static let magicPacket = Data([
+    0x48, 0x54, 0x52, 0x4B, // 'HTRK'
+    0x00, 0x01 // Version
+  ])
+  
+  var connection: NWConnection?
+  
+  var bytes = Data()
+  var maxDataLength: Int = 0
+  var serverCount: Int = 0
+  
+  @Published var connectionStatus: HotlineTrackerStatus = .disconnected
+  @Published var servers: [HotlineServer] = []
+  
+  init(address: String, callback: @escaping ([HotlineServer]) -> Void) {
+    self.serverAddress = NWEndpoint.Host(address)
+    self.callback = callback
+  }
+  
+  func fetch() {
+    self.reset()
+    self.connect()
+  }
+  
+  private func reset() {
+    self.maxDataLength = 0
+    self.serverCount = 0
+  }
+  
+  private func connect() {
+    self.connection = NWConnection(host: self.serverAddress, port: self.serverPort, using: .tcp)
+    self.connection?.stateUpdateHandler = { [weak self] (newState: NWConnection.State) in
+      switch newState {
+      case .ready:
+        print("READY TO SEND AND RECEIVE DATA")
+        self?.connectionStatus = .connected
+        self?.sendMagic()
+      case .cancelled:
+        print("CONNECTION CANCELLED")
+        self?.connectionStatus = .disconnected
+      case .failed(let err):
+        print("CONNECTION ERROR \(err)")
+        self?.connectionStatus = .disconnected
+      default:
+        print("CONNECTION OTHER THING")
+      }
+    }
+    
+    self.connectionStatus = .connecting
+    self.connection?.start(queue: .global())
+  }
+  
+  private func disconnect() {
+    guard let c = connection else {
+      print("HotlineTracker: already disconnected")
+      return
+    }
+    
+    c.cancel()
+    self.connection = nil
+  }
+  
+  private func sendMagic() {
+    guard let c = connection else {
+      print("HotlineTracker: invalid connection to send magic.")
+      return
+    }
+    
+//    let packet: [UInt8] = [0x48, 0x54, 0x52, 0x4B, 0x00, self.serverVersion]
+    
+    c.send(content: HotlineTracker.magicPacket, completion: .contentProcessed { [weak self] (error) in
+      if let err = error {
+        print("HotlineTracker: sending magic failed \(err)")
+        return
+      }
+      
+      print("HotlineTracker: sent magic!")
+      
+      self?.receiveMagic()
+    })
+  }
+  
+  private func receiveMagic() {
+    guard let c = connection else {
+      print("HotlineTracker: invalid connection to receive magic.")
+      return
+    }
+    
+    print("HotlineTracker: receiving...")
+    c.receive(minimumIncompleteLength: 6, maximumLength: 6) { [weak self] (data, context, isComplete, error) in
+      guard let self = self, let data = data else {
+        return
+      }
+      
+      if data.isEmpty || !data.elementsEqual(HotlineTracker.magicPacket) {
+        print("HotlineTracker: invalid magic response")
+        self.disconnect()
+        return
+      }
+//      if let data = data, !data.isEmpty {
+      print("HotlineTracker: received magic response!")
+//      }
+      
+      if let error = error {
+        print("HotlineTracker: receive error \(error)")
+      }
+      else {
+        self.receiveHeader()
+      }
+    }
+  }
+  
+  private func receiveHeader() {
+    guard let c = connection else {
+      print("HotlineTracker: invalid connection to receive header.")
+      return
+    }
+    
+    print("HotlineTracker: receiving...")
+    c.receive(minimumIncompleteLength: 8, maximumLength: 8) { [weak self] (data, context, isComplete, error) in
+      guard let self = self else {
+        return
+      }
+      
+      if let error = error {
+        print("HotlineTracker: receive error \(error)")
+        self.disconnect()
+        return
+      }
+      
+      if let data = data, !data.isEmpty {
+        print("HotlineTracker: received \(data.count) header bytes")
+
+        self.maxDataLength = Int(data[2]) * 0xFF + Int(data[3])
+        self.maxDataLength -= 4
+        print("HotlineTracker: message size = \(self.maxDataLength)")
+        
+        self.serverCount = Int(data[4]) * 256 + Int(data[5])
+        print("HotlineTracker: server count = \(self.serverCount)")
+      }
+      
+      if let error = error {
+        print("HotlineTracker: receive error \(error)")
+      }
+      else {
+        self.receiveListing()
+      }
+    }
+  }
+  
+  private func receiveListing() {
+    guard let c = connection else {
+      print("HotlineTracker: invalid connection to receive data.")
+      return
+    }
+    
+    print("HotlineTracker: receiving...")
+    c.receive(minimumIncompleteLength: 1, maximumLength: 64 * 1024) { [weak self] (data, context, isComplete, error) in
+      guard let self = self else {
+        return
+      }
+            
+      if let data = data, !data.isEmpty {
+        print("HotlineTracker: received \(data.count) bytes")
+        self.bytes.append(contentsOf: data)
+        
+        if bytes.count >= maxDataLength {
+          print("HotlineTracker: done with data, should close. \(self.bytes.count) \(self.maxDataLength)")
+          self.disconnect()
+          self.parseListing()
+          return
+        }
+      }
+      
+      if let error = error {
+        print("HotlineTracker: receive error \(error)")
+        self.disconnect()
+      }
+      else {
+        print("HotlineTracker: not complete")
+        self.receiveListing()
+      }
+    }
+  }
+  
+  private func parseListing() {
+    // IP address (4 bytes)
+    // Port number (2 bytes)
+    // Number of users (2 bytes)
+    // Unused (2 bytes)
+    // Name size (1 byte)
+    // Name (name size)
+    // Description size (1 byte)
+    // Description (description size)
+    
+    var servers: [HotlineServer] = []
+    
+    var cursor = 0
+    for _ in 1...self.serverCount {
+      if self.bytes.count < cursor + 12 {
+        print("HotlineTracker: Data isn't long enough for next server")
+        break
+      }
+      
+      if
+        let ip_1 = self.bytes.readUInt8(at: cursor),
+        let ip_2 = self.bytes.readUInt8(at: cursor + 1),
+        let ip_3 = self.bytes.readUInt8(at: cursor + 2),
+        let ip_4 = self.bytes.readUInt8(at: cursor + 3),
+        let port = self.bytes.readUInt16(at: cursor + 4),
+        let userCount = self.bytes.readUInt16(at: cursor + 6),
+        let nameLengthByte = self.bytes.readUInt8(at: cursor + 10) {
+        
+        let nameLength = Int(nameLengthByte)
+        if let name = self.bytes.readString(at: cursor + 11, length: nameLength, encoding: .utf8) ?? self.bytes.readString(at: cursor + 11, length: nameLength, encoding: .ascii) {
+          if let descLengthByte = self.bytes.readUInt8(at: cursor + 11 + nameLength) {
+            let descLength = Int(descLengthByte)
+            if let desc = self.bytes.readString(at: cursor + 11 + nameLength + 1, length: descLength, encoding: .utf8) ?? self.bytes.readString(at: cursor + 11 + nameLength + 1, length: descLength, encoding: .ascii) {
+              let server = HotlineServer(address: "\(ip_1).\(ip_2).\(ip_3).\(ip_4)", port: port, users: userCount, name: name, description: desc)
+              
+              print("SERVER: \(server)")
+              
+              servers.append(server)
+              
+              cursor += 11 + nameLength + 1 + descLength
+            }
+          }
+        }
+      }
+      
+      print(cursor)
+    }
+    
+    DispatchQueue.main.async {
+      print("CALLING CALLBACK")
+      self.servers = servers
+      self.callback(servers)
+    }
+    
+  }
+}