mirror of
https://github.com/wanghongenpin/proxypin.git
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326 lines
10 KiB
Swift
326 lines
10 KiB
Swift
//
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// TCPPacketFactory.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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//
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import Foundation
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import os.log
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/// Factory class for creating TCP packets.
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class TCPPacketFactory {
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public static let TCP_HEADER_LENGTH = 20
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//从tcp报文创建tcpHeader
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static func createTCPHeader(data: Data) -> TCPHeader? {
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if data.count < TCP_HEADER_LENGTH {
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os_log("Data is too short to be a TCP packet", log: OSLog.default, type: .error)
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return nil
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}
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var offset = 0
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func readUInt16() -> UInt16 {
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let value = data.withUnsafeBytes { $0.load(fromByteOffset: offset, as: UInt16.self).bigEndian }
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offset += 2
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return value
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}
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func readUInt32() -> UInt32 {
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let value = data.withUnsafeBytes { $0.load(fromByteOffset: offset, as: UInt32.self).bigEndian }
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offset += 4
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return value
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}
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let sourcePort = readUInt16()
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let destinationPort = readUInt16()
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let sequenceNumber = readUInt32()
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let ackNumber = readUInt32()
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let dataOffsetAndReserved = data[offset]
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offset += 1
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let dataOffset = UInt8((dataOffsetAndReserved & 0xF0) >> 4)
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let isNs = (dataOffsetAndReserved & 0x01) == 1
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let flags = UInt8(data[offset])
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offset += 1
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let windowSize = readUInt16()
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let checksum = readUInt16()
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let urgentPointer = readUInt16()
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var optionsSize = Int(dataOffset) - 5
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var options: Data?
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if (optionsSize > 0) {
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optionsSize *= 4
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options = data.subdata(in: offset..<offset + optionsSize)
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}
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let payload: Data? = offset < data.count ? data.subdata(in: offset..<data.count) : nil
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return TCPHeader(
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sourcePort: sourcePort,
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destinationPort: destinationPort,
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sequenceNumber: sequenceNumber,
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ackNumber: ackNumber,
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dataOffset: dataOffset,
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isNS: isNs,
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flags: flags,
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windowSize: windowSize,
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checksum: checksum,
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urgentPointer: urgentPointer,
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options: options,
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payload: payload
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)
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}
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//向客户端确认服务器已收到请求
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static func createResponseAckData(ipHeader: IP4Header, tcpHeader: TCPHeader, ackToClient: UInt32) -> Data {
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var ip = ipHeader.copy()
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var tcp = tcpHeader.copy()
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flipIp(ip: &ip, tcp: &tcp)
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let seqNumber = tcp.ackNumber
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tcp.ackNumber = ackToClient
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tcp.sequenceNumber = seqNumber
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ip.identification = UInt16(truncatingIfNeeded: PacketUtil.getPacketId())
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// Set TCP flags
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tcp.setIsACK(true)
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tcp.setIsSYN(false)
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tcp.setIsPSH(false)
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tcp.setIsFIN(false)
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tcp.dataOffset = 5 // tcp header length 5 * 4 = 20 bytes
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tcp.options = nil
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ip.totalLength = UInt16(ip.getIPHeaderLength() + tcp.getTCPHeaderLength())
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return createPacketData(ipHeader: ip, tcpHeader: tcp, data: nil)
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}
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///创建带有RST标志的数据包，以便在需要重置时发送到客户端。
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static func createRstData(ipHeader: IP4Header, tcpHeader: TCPHeader, dataLength: Int) -> Data {
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var ip = ipHeader.copy()
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var tcp = tcpHeader.copy()
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var ackNumber: UInt32 = 0
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var seqNumber: UInt32 = 0
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if tcp.ackNumber > 0 {
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seqNumber = tcp.ackNumber
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} else {
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ackNumber = tcp.sequenceNumber + UInt32(dataLength)
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}
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tcp.ackNumber = ackNumber
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tcp.sequenceNumber = seqNumber
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// Flip IP from source to destination
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flipIp(ip: &ip, tcp: &tcp)
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ip.identification = 0
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tcp.flags = 0
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tcp.isNS = false
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tcp.setIsRST(true)
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tcp.dataOffset = 5
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tcp.options = nil
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tcp.windowSize = 0
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// Recalculate IP length
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let totalLength = ip.getIPHeaderLength() + tcp.getTCPHeaderLength()
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ip.totalLength = UInt16(totalLength)
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return createPacketData(ipHeader: ip, tcpHeader: tcp, data: nil)
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}
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//创建发送到客户端的FIN-ACK
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static func createFinAckData(ipHeader: IP4Header, tcpHeader: TCPHeader, ackToClient: UInt32, seqToClient: UInt32, isFin: Bool, isAck: Bool) -> Data {
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var ip = ipHeader.copy()
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var tcp = tcpHeader.copy()
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flipIp(ip: &ip, tcp: &tcp)
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tcp.dataOffset = 5 // tcp header length 5 * 4 = 20 bytes
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tcp.options = nil
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tcp.ackNumber = ackToClient
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tcp.sequenceNumber = seqToClient
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ip.identification = UInt16(truncatingIfNeeded: PacketUtil.getPacketId())
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tcp.setIsACK(isAck)
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tcp.setIsSYN(false)
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tcp.setIsPSH(false)
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tcp.setIsFIN(isFin)
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ip.totalLength = UInt16(ip.getIPHeaderLength() + tcp.getTCPHeaderLength())
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return createPacketData(ipHeader: ip, tcpHeader: tcp, data: nil)
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}
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//通过写回客户端流创建SYN-ACK数据包数据
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public static func createSynAckPacketData(ipHeader: IP4Header, tcpHeader: TCPHeader) -> Packet {
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var ip = ipHeader.copy()
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var tcp = tcpHeader.copy()
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flipIp(ip: &ip, tcp: &tcp)
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tcp.dataOffset = 5 // tcp header length 5 * 4 = 20 bytes
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tcp.options = nil
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// ack = received sequence + 1
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let ackNumber = tcpHeader.sequenceNumber + 1
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tcp.ackNumber = ackNumber
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// Server-generated initial sequence number
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let seqNumber = UInt64.random(in: 0..<100000)
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tcp.sequenceNumber = UInt32(seqNumber)
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// SYN-ACK
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tcp.setIsACK(true)
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tcp.setIsSYN(true)
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tcp.timeStampReplyTo = tcp.timeStampSender
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tcp.timeStampSender = PacketUtil.currentTime
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ip.totalLength = UInt16(ip.getIPHeaderLength() + tcp.getTCPHeaderLength())
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return Packet(ipHeader: ip, transportHeader: tcp, buffer: createPacketData(ipHeader: ip, tcpHeader: tcp, data: nil))
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}
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//创建数据包数据以发送回客户端
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public static func createResponsePacketData(
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ipHeader: IP4Header, tcpHeader: TCPHeader, packetData: Data?, isPsh: Bool,
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ackNumber: UInt32, seqNumber: UInt32, timeSender: Int, timeReplyTo: Int
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) -> Data {
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var ip = ipHeader.copy()
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var tcp = tcpHeader.copy()
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flipIp(ip: &ip, tcp: &tcp)
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tcp.dataOffset = 5 // tcp header length 5 * 4 = 20 bytes
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tcp.options = nil
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tcp.ackNumber = ackNumber
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tcp.sequenceNumber = seqNumber
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ip.identification = UInt16(truncatingIfNeeded: PacketUtil.getPacketId())
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// ACK is always sent
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tcp.setIsACK(true)
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tcp.setIsSYN(false)
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tcp.setIsPSH(isPsh)
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tcp.setIsFIN(false)
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tcp.timeStampSender = timeSender
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tcp.timeStampReplyTo = timeReplyTo
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var totalLength = ip.getIPHeaderLength() + tcp.getTCPHeaderLength()
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if let packetData = packetData {
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totalLength += packetData.count
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}
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ip.totalLength = UInt16(totalLength)
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return createPacketData(ipHeader: ip, tcpHeader: tcp, data: packetData)
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}
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//将IP从源翻转到目标
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private static func flipIp(ip: inout IP4Header, tcp: inout TCPHeader) {
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let sourceIp = ip.destinationIP
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let destIp = ip.sourceIP
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let sourcePort = tcp.destinationPort
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let destPort = tcp.sourcePort
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ip.destinationIP = destIp
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ip.sourceIP = sourceIp
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tcp.destinationPort = destPort
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tcp.sourcePort = sourcePort
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}
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public static func createFinData(
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ipHeader: IP4Header, tcpHeader: TCPHeader, ackNumber: UInt32, seqNumber: UInt32,
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timeSender: Int, timeReplyTo: Int
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) -> Data {
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var ip = ipHeader.copy()
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var tcp = tcpHeader.copy()
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flipIp(ip: &ip, tcp: &tcp)
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tcp.ackNumber = ackNumber
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tcp.sequenceNumber = seqNumber
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ip.identification = UInt16(truncatingIfNeeded: PacketUtil.getPacketId())
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tcp.timeStampReplyTo = timeReplyTo
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tcp.timeStampSender = timeSender
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tcp.flags = 0
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tcp.isNS = false
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tcp.setIsACK(true)
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tcp.setIsFIN(true)
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tcp.options = nil
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tcp.windowSize = 0
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ip.totalLength = UInt16(ip.getIPHeaderLength() + TCP_HEADER_LENGTH)
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return createPacketData(ipHeader: ip, tcpHeader: tcp, data: nil)
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}
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//从tcpHeader创建tcp报文
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private static func createPacketData(ipHeader: IP4Header, tcpHeader: TCPHeader, data: Data?) -> Data {
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let dataLength = data?.count ?? 0
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var buffer = Data()
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// Add IP header
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let ipBuffer = ipHeader.toBytes()
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buffer.append(ipBuffer)
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// Add TCP header
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let tcpBuffer = tcpHeader.toBytes()
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buffer.append(tcpBuffer)
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// Add data if exists
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if let data = data {
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buffer.append(data)
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}
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// Zero out IP checksum
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buffer[10] = 0
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buffer[11] = 0
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// Calculate IP checksum
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let ipChecksum = PacketUtil.calculateChecksum(data: buffer, offset: 0, length: ipBuffer.count)
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buffer[10] = ipChecksum[0]
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buffer[11] = ipChecksum[1]
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// IPPacketFactory.printPacket(data: ipBuffer)
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// Zero out TCP checksum
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let tcpStart = ipBuffer.count
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buffer[tcpStart + 16] = 0
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buffer[tcpStart + 17] = 0
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// Calculate TCP checksum
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let tcpChecksum = PacketUtil.calculateTCPHeaderChecksum(
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data: buffer, offset: tcpStart, tcpLength: tcpBuffer.count + dataLength,
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sourceIP: ipHeader.sourceIP, destinationIP: ipHeader.destinationIP
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)
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buffer[tcpStart + 16] = tcpChecksum[0]
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buffer[tcpStart + 17] = tcpChecksum[1]
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return buffer
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}
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static func printPacket(data: Data) {
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guard let tcpHeader = createTCPHeader(data: data) else {
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os_log("Failed to create TCP header", log: OSLog.default, type: .error)
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return
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}
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os_log("TCP Header: sourcePort: %{public}d, destinationPort: %{public}d, sequenceNumber: %{public}u, ackNumber: %{public}u, dataOffset: %{public}d, isNS: %{public}d, flags: %{public}d, windowSize: %{public}d, checksum: %{public}u, urgentPointer: %{public}u",
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log: OSLog.default, type: .default, tcpHeader.sourcePort, tcpHeader.destinationPort, tcpHeader.sequenceNumber, tcpHeader.ackNumber, tcpHeader.dataOffset, tcpHeader.isNS ? 1 : 0, tcpHeader.flags, tcpHeader.windowSize, tcpHeader.checksum, tcpHeader.urgentPointer)
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}
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}
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