mirror of
https://github.com/wanghongenpin/proxypin.git
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162 lines
7.1 KiB
Swift
162 lines
7.1 KiB
Swift
//
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// IP4Header.swift
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// ProxyPin
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//
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// Created by wanghongen on 2024/9/16.
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//
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import Foundation
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import os.log
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// IPv4 header data structure
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class IP4Header {
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var ipVersion: UInt8 // 对于IPv4，其值为4（因此命名为IPv4）。 4bit
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var internetHeaderLength: UInt8 // 头部长度 4bit
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var diffTypeOfService: UInt8 // 差分服务代码点 =>6位
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var ecn: UInt8 // 显式拥塞通知（ECN）
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var totalLength: UInt16 // 此IP数据包的总长度 16bit
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var identification: UInt16 // 主要用于唯一标识单个IP数据报的片段组。 16bit
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var mayFragment: Bool // 用于指示数据报是否可以分段。 1bit
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var lastFragment: Bool // 用于指示数据报是否是片段中的最后一个。 1bit
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var fragmentOffset: UInt16 // 指定特定片段相对于原始未分段的IP数据报的开始的偏移量。 13bit
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var timeToLive: UInt8 // 用于防止数据报持续存在。8bit
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var protocolNumber: UInt8 // 定义IP数据报的数据部分中使用的协议。 8bit
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var headerChecksum: UInt16 // 用于对头部进行错误检查的16位字段。 16bit
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var sourceIP: UInt32 // 发送者的IPv4地址。 32bit
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var destinationIP: UInt32 // 接收者的IPv4地址。 32bit
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//用于控制或识别片段的3比特字段。
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//bit 0: 保留；必须为零
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//bit 1: Don't Fragment (DF)
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//bit 2: More Fragments (MF)
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private var flag: UInt8
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init(
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ipVersion: UInt8, internetHeaderLength: UInt8, diffTypeOfService: UInt8, ecn: UInt8, totalLength: UInt16, identification: UInt16,
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mayFragment: Bool, lastFragment: Bool, fragmentOffset: UInt16, timeToLive: UInt8, protocolNumber: UInt8, headerChecksum: UInt16,
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sourceIP: UInt32, destinationIP: UInt32
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) {
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self.ipVersion = ipVersion
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self.internetHeaderLength = internetHeaderLength
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self.diffTypeOfService = diffTypeOfService
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self.ecn = ecn
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self.totalLength = totalLength
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self.identification = identification
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self.mayFragment = mayFragment
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self.lastFragment = lastFragment
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self.fragmentOffset = fragmentOffset
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self.timeToLive = timeToLive
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self.protocolNumber = protocolNumber
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self.headerChecksum = headerChecksum
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self.sourceIP = sourceIP
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self.destinationIP = destinationIP
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self.flag = IP4Header.initFlag(mayFragment: mayFragment, lastFragment: lastFragment)
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}
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private static func initFlag(mayFragment: Bool, lastFragment: Bool) -> UInt8 {
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var initFlag: UInt8 = 0
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if mayFragment {
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initFlag = 0x40
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}
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if lastFragment {
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initFlag |= 0x20
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}
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return initFlag
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}
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func setMayFragment(_ mayFragment: Bool) {
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self.mayFragment = mayFragment
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flag = mayFragment ? (flag | 0x40) : (flag & 0xBF)
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}
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func getIPHeaderLength() -> Int {
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return Int(internetHeaderLength * 4)
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}
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func copy() -> IP4Header {
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return IP4Header(
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ipVersion: ipVersion, internetHeaderLength: internetHeaderLength, diffTypeOfService: diffTypeOfService, ecn: ecn, totalLength: totalLength, identification: identification,
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mayFragment: mayFragment, lastFragment: lastFragment, fragmentOffset: fragmentOffset, timeToLive: timeToLive, protocolNumber: protocolNumber, headerChecksum: headerChecksum,
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sourceIP: sourceIP, destinationIP: destinationIP
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)
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}
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func toBytes() -> Data {
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var buffer = Data()
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buffer.append(UInt8((ipVersion << 4) + internetHeaderLength))
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buffer.append(UInt8((diffTypeOfService << 2) + ecn))
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buffer.append(contentsOf: totalLength.bytes)
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buffer.append(contentsOf: identification.bytes)
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//组合标志和部分片段偏移
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buffer.append(UInt8((fragmentOffset >> 8) & 0x1F) | flag)
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buffer.append(UInt8(fragmentOffset & 0xFF))
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buffer.append(timeToLive)
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buffer.append(protocolNumber)
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buffer.append(contentsOf: headerChecksum.bytes)
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buffer.append(contentsOf: sourceIP.bytes)
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buffer.append(contentsOf: destinationIP.bytes)
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return buffer
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}
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}
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class IPPacketFactory {
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static let IP4_HEADER_SIZE = 20
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static let IP4_VERSION: UInt8 = 0x04
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//从给定的ByteBuffer流创建IPv4标头
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static func createIP4Header(data: Data) -> IP4Header? {
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guard data.count >= IP4_HEADER_SIZE else {
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return nil
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}
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let buffer = [UInt8](data)
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let versionAndHeaderLength = buffer[0]
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let ipVersion = versionAndHeaderLength >> 4
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guard ipVersion == IP4_VERSION else {
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return nil
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}
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let internetHeaderLength = versionAndHeaderLength & 0x0F
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let typeOfService = buffer[1]
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let diffTypeOfService = typeOfService >> 2
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let ecn = typeOfService & 0x03
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let totalLength = UInt16(buffer[2]) << 8 | UInt16(buffer[3])
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let identification = UInt16(buffer[4]) << 8 | UInt16(buffer[5])
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let flagsAndFragmentOffset = UInt16(buffer[6]) << 8 | UInt16(buffer[7])
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let mayFragment = (flagsAndFragmentOffset & 0x4000) != 0
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let lastFragment = (flagsAndFragmentOffset & 0x2000) != 0
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let fragmentOffset = flagsAndFragmentOffset & 0x1FFF
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let timeToLive = buffer[8]
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let protocolNumber = buffer[9]
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let checksum = UInt16(buffer[10]) << 8 | UInt16(buffer[11])
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let sourceIp = UInt32(buffer[12]) << 24 | UInt32(buffer[13]) << 16 | UInt32(buffer[14]) << 8 | UInt32(buffer[15])
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let desIp = UInt32(buffer[16]) << 24 | UInt32(buffer[17]) << 16 | UInt32(buffer[18]) << 8 | UInt32(buffer[19])
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if internetHeaderLength > 5 {
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// drop the IP option
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for _ in 0..<(internetHeaderLength - 5) {
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// Skip the IP options
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}
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}
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return IP4Header(
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ipVersion: ipVersion, internetHeaderLength: internetHeaderLength, diffTypeOfService: diffTypeOfService, ecn: ecn, totalLength: totalLength, identification: identification,
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mayFragment: mayFragment, lastFragment: lastFragment, fragmentOffset: fragmentOffset, timeToLive: timeToLive, protocolNumber: protocolNumber, headerChecksum: checksum,
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sourceIP: sourceIp, destinationIP: desIp
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)
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}
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public static func printPacket(data: Data) {
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guard let ipHeader = createIP4Header(data: data) else {
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return
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}
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os_log("IP Header: version: %{public}d, internetHeaderLength: %{public}d, diffTypeOfService: %{public}d, ecn: %{public}d, totalLength: %{public}d, identification: %{public}d, mayFragment: %{public}d, lastFragment: %{public}d, fragmentOffset: %{public}d, timeToLive: %{public}d, protocolNumber: %{public}d, headerChecksum: %{public}d, sourceIP: %{public}@, destinationIP: %{public}@", log: OSLog.default, type: .default, ipHeader.ipVersion, ipHeader.internetHeaderLength, ipHeader.diffTypeOfService, ipHeader.ecn, ipHeader.totalLength, ipHeader.identification, ipHeader.mayFragment, ipHeader.lastFragment, ipHeader.fragmentOffset, ipHeader.timeToLive, ipHeader.protocolNumber, ipHeader.headerChecksum, PacketUtil.intToIPAddress(ipHeader.sourceIP), PacketUtil.intToIPAddress(ipHeader.destinationIP))
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}
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}
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