115 lines
3.9 KiB
Swift
115 lines
3.9 KiB
Swift
//
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// SDLTunPacketRouter.swift
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// Tun
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//
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// Created by 安礼成 on 2026/4/14.
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//
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import Foundation
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struct SDLTunPacketRouter {
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enum DropReason: String {
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case invalidDNSRequest
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case noRoute
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}
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enum ForwardKind {
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case sameNetwork
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case exitNode
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case dnsExitNode
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}
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enum RouteDecision {
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case loopback(ipPacketData: Data)
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case cloudDNS(name: String, ipPacketData: Data)
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case localDNS(name: String, payload: Data, tracker: DNSLocalClient.DNSTracker)
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case forwardToNextHop(ip: UInt32, type: LayerPacket.PacketType, data: Data, kind: ForwardKind)
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case drop(reason: DropReason)
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}
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let networkAddress: SDLConfiguration.NetworkAddress
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let exitNode: SDLConfiguration.ExitNode?
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func route(packet: IPPacket, now: Date = Date()) -> RouteDecision {
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let dstIp = packet.header.destination
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// 本地通讯, 目标地址是本地服务器的ip地址
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if dstIp == self.networkAddress.ip {
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return .loopback(ipPacketData: packet.data)
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}
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// 处理dns的解析
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if let dnsDecision = self.routeDNS(packet: packet, now: now) {
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return dnsDecision
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}
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// 判断目标地址是否和当前的网络地址是否在同一个网段
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// 只有在同一个网段的ip数据才直接发送
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if SDLUtil.inSameNetwork(ip: dstIp, compareIp: self.networkAddress.ip, maskLen: self.networkAddress.maskLen) {
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return .forwardToNextHop(ip: dstIp, type: .ipv4, data: packet.data, kind: .sameNetwork)
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}
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// 不在同一个网段的数据，看是否配置了网络出口, 如果配置了，转发数据个网络出口，否则丢弃
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if let exitNode = self.exitNode {
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return .forwardToNextHop(ip: exitNode.exitNodeIp, type: .ipv4, data: packet.data, kind: .exitNode)
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}
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return .drop(reason: .noRoute)
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}
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private func routeDNS(packet: IPPacket, now: Date) -> RouteDecision? {
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guard DNSHelper.isDnsRequestPacket(ipPacket: packet) else {
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return nil
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}
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guard case .udp(let udpPacket) = packet.transportPacket else {
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return .drop(reason: .invalidDNSRequest)
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}
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// 数据是通过offset解析的, dns查询必然是udp包
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let payloadOffset = udpPacket.payloadOffset
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let dnsParser = DNSParser(data: packet.data, offset: payloadOffset)
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guard let dnsMessage = dnsParser.parse(), let name = dnsMessage.questions.first?.name else {
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return .drop(reason: .invalidDNSRequest)
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}
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// 如果是内部域名，则转发整个ip包的内容到云端服务器
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if name.contains(self.networkAddress.networkDomain) {
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return .cloudDNS(name: name, ipPacketData: packet.data)
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}
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// 如果开启了出口节点，则转发给出口节点
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if let exitNode = self.exitNode {
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return .forwardToNextHop(ip: exitNode.exitNodeIp, type: .ipv4, data: packet.data, kind: .dnsExitNode)
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}
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// 通过本地的dns解析，发送的是udp的payload部分
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let dnsPayload = Data(packet.data[payloadOffset..<packet.data.count])
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let tracker = DNSLocalClient.DNSTracker(
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transactionID: dnsMessage.transactionID,
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clientIP: packet.header.source,
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clientPort: udpPacket.srcPort,
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createdAt: now
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)
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return .localDNS(name: name, payload: dnsPayload, tracker: tracker)
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}
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}
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extension SDLTunPacketRouter.RouteDecision {
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var shouldTrackFlow: Bool {
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switch self {
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case .forwardToNextHop(_, _, _, let kind):
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switch kind {
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case .sameNetwork, .exitNode:
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return true
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case .dnsExitNode:
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return false
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}
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default:
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return false
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}
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}
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}
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