tunnelkit/TunnelKit/Sources/Protocols/OpenVPN/AppExtension/NEUDPLink.swift

//
//  NEUDPLink.swift
//  TunnelKit
//
//  Created by Davide De Rosa on 5/23/19.
//  Copyright (c) 2021 Davide De Rosa. All rights reserved.
//
//  https://github.com/passepartoutvpn
//
//  This file is part of TunnelKit.
//
//  TunnelKit is free software: you can redistribute it and/or modify
//  it under the terms of the GNU General Public License as published by
//  the Free Software Foundation, either version 3 of the License, or
//  (at your option) any later version.
//
//  TunnelKit is distributed in the hope that it will be useful,
//  but WITHOUT ANY WARRANTY; without even the implied warranty of
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//  GNU General Public License for more details.
//
//  You should have received a copy of the GNU General Public License
//  along with TunnelKit.  If not, see <http://www.gnu.org/licenses/>.
//

import Foundation
import NetworkExtension

class NEUDPLink: LinkInterface {
    private let impl: NWUDPSession
    
    private let maxDatagrams: Int
    
    init(impl: NWUDPSession, mtu: Int, maxDatagrams: Int? = nil) {
        self.impl = impl
        self.mtu = mtu
        self.maxDatagrams = maxDatagrams ?? 200
    }
    
    // MARK: LinkInterface
    
    let isReliable: Bool = false
    
    var remoteAddress: String? {
        return (impl.resolvedEndpoint as? NWHostEndpoint)?.hostname
    }
    
    let mtu: Int
    
    var packetBufferSize: Int {
        return maxDatagrams
    }
    
    func setReadHandler(queue: DispatchQueue, _ handler: @escaping ([Data]?, Error?) -> Void) {
        
        // WARNING: runs in Network.framework queue
        impl.setReadHandler({ [weak self] (packets, error) in
            guard let _ = self else {
                return
            }
            queue.sync {
                handler(packets, error)
            }
            }, maxDatagrams: maxDatagrams)
    }
    
    func writePacket(_ packet: Data, completionHandler: ((Error?) -> Void)?) {
        impl.writeDatagram(packet) { (error) in
            completionHandler?(error)
        }
    }
    
    func writePackets(_ packets: [Data], completionHandler: ((Error?) -> Void)?) {
        impl.writeMultipleDatagrams(packets) { (error) in
            completionHandler?(error)
        }
    }
}

/// :nodoc:
extension NEUDPSocket: LinkProducer {
    public func link(withMTU mtu: Int) -> LinkInterface {
        return NEUDPLink(impl: impl, mtu: mtu)
    }
}