|
| 1 | +//go:build linux |
| 2 | + |
| 3 | +package tun |
| 4 | + |
| 5 | +import ( |
| 6 | + "context" |
| 7 | + "errors" |
| 8 | + "sync" |
| 9 | + "sync/atomic" |
| 10 | + |
| 11 | + "github.com/sagernet/sing-tun/internal/gtcpip/header" |
| 12 | + E "github.com/sagernet/sing/common/exceptions" |
| 13 | + "github.com/sagernet/sing/common/logger" |
| 14 | + M "github.com/sagernet/sing/common/metadata" |
| 15 | + N "github.com/sagernet/sing/common/network" |
| 16 | + |
| 17 | + "github.com/florianl/go-nfqueue/v2" |
| 18 | + "github.com/mdlayher/netlink" |
| 19 | + "golang.org/x/sys/unix" |
| 20 | +) |
| 21 | + |
| 22 | +const nfqueueMaxPacketLen = 512 |
| 23 | + |
| 24 | +type nfqueueHandler struct { |
| 25 | + ctx context.Context |
| 26 | + cancel context.CancelFunc |
| 27 | + handler Handler |
| 28 | + logger logger.Logger |
| 29 | + nfq *nfqueue.Nfqueue |
| 30 | + queue uint16 |
| 31 | + outputMark uint32 |
| 32 | + resetMark uint32 |
| 33 | + wg sync.WaitGroup |
| 34 | + closed atomic.Bool |
| 35 | +} |
| 36 | + |
| 37 | +type nfqueueOptions struct { |
| 38 | + Context context.Context |
| 39 | + Handler Handler |
| 40 | + Logger logger.Logger |
| 41 | + Queue uint16 |
| 42 | + OutputMark uint32 |
| 43 | + ResetMark uint32 |
| 44 | +} |
| 45 | + |
| 46 | +func newNFQueueHandler(options nfqueueOptions) (*nfqueueHandler, error) { |
| 47 | + ctx, cancel := context.WithCancel(options.Context) |
| 48 | + return &nfqueueHandler{ |
| 49 | + ctx: ctx, |
| 50 | + cancel: cancel, |
| 51 | + handler: options.Handler, |
| 52 | + logger: options.Logger, |
| 53 | + queue: options.Queue, |
| 54 | + outputMark: options.OutputMark, |
| 55 | + resetMark: options.ResetMark, |
| 56 | + }, nil |
| 57 | +} |
| 58 | + |
| 59 | +func (h *nfqueueHandler) setVerdict(packetID uint32, verdict int, mark uint32) { |
| 60 | + var err error |
| 61 | + if mark != 0 { |
| 62 | + err = h.nfq.SetVerdictWithOption(packetID, verdict, nfqueue.WithMark(mark)) |
| 63 | + } else { |
| 64 | + err = h.nfq.SetVerdict(packetID, verdict) |
| 65 | + } |
| 66 | + if err != nil && !h.closed.Load() && h.ctx.Err() == nil { |
| 67 | + h.logger.Trace(E.Cause(err, "set verdict")) |
| 68 | + } |
| 69 | +} |
| 70 | + |
| 71 | +func (h *nfqueueHandler) Start() error { |
| 72 | + config := nfqueue.Config{ |
| 73 | + NfQueue: h.queue, |
| 74 | + MaxPacketLen: nfqueueMaxPacketLen, |
| 75 | + MaxQueueLen: 4096, |
| 76 | + Copymode: nfqueue.NfQnlCopyPacket, |
| 77 | + AfFamily: unix.AF_UNSPEC, |
| 78 | + Flags: nfqueue.NfQaCfgFlagFailOpen, |
| 79 | + } |
| 80 | + |
| 81 | + nfq, err := nfqueue.Open(&config) |
| 82 | + if err != nil { |
| 83 | + return E.Cause(err, "open nfqueue") |
| 84 | + } |
| 85 | + h.nfq = nfq |
| 86 | + |
| 87 | + if err = nfq.SetOption(netlink.NoENOBUFS, true); err != nil { |
| 88 | + h.nfq.Close() |
| 89 | + return E.Cause(err, "set nfqueue option") |
| 90 | + } |
| 91 | + |
| 92 | + h.wg.Add(1) |
| 93 | + go func() { |
| 94 | + defer h.wg.Done() |
| 95 | + err := nfq.RegisterWithErrorFunc(h.ctx, h.handlePacket, func(e error) int { |
| 96 | + if h.ctx.Err() != nil { |
| 97 | + return 1 |
| 98 | + } |
| 99 | + h.logger.Error("nfqueue error: ", e) |
| 100 | + return 0 |
| 101 | + }) |
| 102 | + if err != nil && h.ctx.Err() == nil { |
| 103 | + h.logger.Error("nfqueue register error: ", err) |
| 104 | + } |
| 105 | + }() |
| 106 | + |
| 107 | + return nil |
| 108 | +} |
| 109 | + |
| 110 | +func parseIPv6TransportHeader(payload []byte) (transportProto uint8, transportOffset int, ok bool) { |
| 111 | + if len(payload) < header.IPv6MinimumSize { |
| 112 | + return 0, 0, false |
| 113 | + } |
| 114 | + |
| 115 | + ipv6 := header.IPv6(payload) |
| 116 | + nextHeader := ipv6.NextHeader() |
| 117 | + offset := header.IPv6MinimumSize |
| 118 | + |
| 119 | + for { |
| 120 | + switch nextHeader { |
| 121 | + case unix.IPPROTO_HOPOPTS, |
| 122 | + unix.IPPROTO_ROUTING, |
| 123 | + unix.IPPROTO_DSTOPTS: |
| 124 | + if len(payload) < offset+2 { |
| 125 | + return 0, 0, false |
| 126 | + } |
| 127 | + nextHeader = payload[offset] |
| 128 | + extLen := int(payload[offset+1]+1) * 8 |
| 129 | + if len(payload) < offset+extLen { |
| 130 | + return 0, 0, false |
| 131 | + } |
| 132 | + offset += extLen |
| 133 | + |
| 134 | + case unix.IPPROTO_FRAGMENT: |
| 135 | + if len(payload) < offset+8 { |
| 136 | + return 0, 0, false |
| 137 | + } |
| 138 | + nextHeader = payload[offset] |
| 139 | + offset += 8 |
| 140 | + |
| 141 | + case unix.IPPROTO_AH: |
| 142 | + if len(payload) < offset+2 { |
| 143 | + return 0, 0, false |
| 144 | + } |
| 145 | + nextHeader = payload[offset] |
| 146 | + extLen := int(payload[offset+1]+2) * 4 |
| 147 | + if len(payload) < offset+extLen { |
| 148 | + return 0, 0, false |
| 149 | + } |
| 150 | + offset += extLen |
| 151 | + |
| 152 | + case unix.IPPROTO_NONE: |
| 153 | + return 0, 0, false |
| 154 | + |
| 155 | + default: |
| 156 | + return nextHeader, offset, true |
| 157 | + } |
| 158 | + } |
| 159 | +} |
| 160 | + |
| 161 | +func (h *nfqueueHandler) handlePacket(attr nfqueue.Attribute) int { |
| 162 | + if h.closed.Load() { |
| 163 | + return 0 |
| 164 | + } |
| 165 | + if attr.PacketID == nil || attr.Payload == nil { |
| 166 | + return 0 |
| 167 | + } |
| 168 | + |
| 169 | + packetID := *attr.PacketID |
| 170 | + payload := *attr.Payload |
| 171 | + |
| 172 | + if len(payload) < header.IPv4MinimumSize { |
| 173 | + h.setVerdict(packetID, nfqueue.NfAccept, 0) |
| 174 | + return 0 |
| 175 | + } |
| 176 | + |
| 177 | + var srcAddr, dstAddr M.Socksaddr |
| 178 | + var tcpOffset int |
| 179 | + |
| 180 | + version := payload[0] >> 4 |
| 181 | + if version == 4 { |
| 182 | + ipv4 := header.IPv4(payload) |
| 183 | + if !ipv4.IsValid(len(payload)) || ipv4.Protocol() != uint8(unix.IPPROTO_TCP) { |
| 184 | + h.setVerdict(packetID, nfqueue.NfAccept, 0) |
| 185 | + return 0 |
| 186 | + } |
| 187 | + srcAddr = M.SocksaddrFrom(ipv4.SourceAddr(), 0) |
| 188 | + dstAddr = M.SocksaddrFrom(ipv4.DestinationAddr(), 0) |
| 189 | + tcpOffset = int(ipv4.HeaderLength()) |
| 190 | + } else if version == 6 { |
| 191 | + transportProto, transportOffset, ok := parseIPv6TransportHeader(payload) |
| 192 | + if !ok || transportProto != unix.IPPROTO_TCP { |
| 193 | + h.setVerdict(packetID, nfqueue.NfAccept, 0) |
| 194 | + return 0 |
| 195 | + } |
| 196 | + ipv6 := header.IPv6(payload) |
| 197 | + srcAddr = M.SocksaddrFrom(ipv6.SourceAddr(), 0) |
| 198 | + dstAddr = M.SocksaddrFrom(ipv6.DestinationAddr(), 0) |
| 199 | + tcpOffset = transportOffset |
| 200 | + } else { |
| 201 | + h.setVerdict(packetID, nfqueue.NfAccept, 0) |
| 202 | + return 0 |
| 203 | + } |
| 204 | + |
| 205 | + if len(payload) < tcpOffset+header.TCPMinimumSize { |
| 206 | + h.setVerdict(packetID, nfqueue.NfAccept, 0) |
| 207 | + return 0 |
| 208 | + } |
| 209 | + |
| 210 | + tcp := header.TCP(payload[tcpOffset:]) |
| 211 | + srcAddr = M.SocksaddrFrom(srcAddr.Addr, tcp.SourcePort()) |
| 212 | + dstAddr = M.SocksaddrFrom(dstAddr.Addr, tcp.DestinationPort()) |
| 213 | + |
| 214 | + flags := tcp.Flags() |
| 215 | + if !flags.Contains(header.TCPFlagSyn) || flags.Contains(header.TCPFlagAck) { |
| 216 | + h.setVerdict(packetID, nfqueue.NfAccept, 0) |
| 217 | + return 0 |
| 218 | + } |
| 219 | + |
| 220 | + _, pErr := h.handler.PrepareConnection(N.NetworkTCP, srcAddr, dstAddr, nil, 0) |
| 221 | + |
| 222 | + switch { |
| 223 | + case errors.Is(pErr, ErrBypass): |
| 224 | + h.setVerdict(packetID, nfqueue.NfAccept, h.outputMark) |
| 225 | + case errors.Is(pErr, ErrReset): |
| 226 | + h.setVerdict(packetID, nfqueue.NfAccept, h.resetMark) |
| 227 | + case errors.Is(pErr, ErrDrop): |
| 228 | + h.setVerdict(packetID, nfqueue.NfDrop, 0) |
| 229 | + default: |
| 230 | + h.setVerdict(packetID, nfqueue.NfAccept, 0) |
| 231 | + } |
| 232 | + |
| 233 | + return 0 |
| 234 | +} |
| 235 | + |
| 236 | +func (h *nfqueueHandler) Close() error { |
| 237 | + h.closed.Store(true) |
| 238 | + h.cancel() |
| 239 | + if h.nfq != nil { |
| 240 | + h.nfq.Close() |
| 241 | + } |
| 242 | + h.wg.Wait() |
| 243 | + return nil |
| 244 | +} |
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