58 lines
1.9 KiB
Swift
58 lines
1.9 KiB
Swift
//
|
|
// IPHeader.swift
|
|
// TunnelKit
|
|
//
|
|
// Created by Davide De Rosa on 5/12/20.
|
|
// 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
|
|
|
|
/// Helper for handling IP headers.
|
|
public struct IPHeader {
|
|
private static let ipV4: UInt8 = 4
|
|
|
|
private static let ipV6: UInt8 = 6
|
|
|
|
private static let ipV4ProtocolNumber = AF_INET as NSNumber
|
|
|
|
private static let ipV6ProtocolNumber = AF_INET6 as NSNumber
|
|
|
|
private static let fallbackProtocolNumber = ipV4ProtocolNumber
|
|
|
|
/**
|
|
Returns the protocol number from the IP header of a data packet.
|
|
|
|
- Parameter packet: The data to inspect.
|
|
- Returns: A protocol number between `AF_INET` and `AF_INET6`.
|
|
*/
|
|
public static func protocolNumber(inPacket packet: Data) -> NSNumber {
|
|
guard !packet.isEmpty else {
|
|
return fallbackProtocolNumber
|
|
}
|
|
|
|
// 'packet' contains the decrypted incoming IP packet data
|
|
|
|
// The first 4 bits identify the IP version
|
|
let ipVersion = (packet[0] & 0xf0) >> 4
|
|
assert(ipVersion == ipV4 || ipVersion == ipV6)
|
|
return (ipVersion == ipV6) ? ipV6ProtocolNumber : ipV4ProtocolNumber
|
|
}
|
|
}
|