mirror of
https://github.com/SagerNet/sing-box.git
synced 2024-11-27 02:51:36 +00:00
100 lines
2.4 KiB
Go
100 lines
2.4 KiB
Go
package sniff
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import (
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"bytes"
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"context"
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"encoding/binary"
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"io"
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"os"
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"github.com/sagernet/sing-box/adapter"
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C "github.com/sagernet/sing-box/constant"
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)
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const (
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trackerConnectFlag = 0
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trackerProtocolID = 0x41727101980
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trackerConnectMinSize = 16
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)
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// BitTorrent detects if the stream is a BitTorrent connection.
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// For the BitTorrent protocol specification, see https://www.bittorrent.org/beps/bep_0003.html
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func BitTorrent(_ context.Context, metadata *adapter.InboundContext, reader io.Reader) error {
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var first byte
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err := binary.Read(reader, binary.BigEndian, &first)
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if err != nil {
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return err
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}
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if first != 19 {
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return os.ErrInvalid
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}
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var protocol [19]byte
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_, err = reader.Read(protocol[:])
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if err != nil {
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return err
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}
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if string(protocol[:]) != "BitTorrent protocol" {
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return os.ErrInvalid
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}
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metadata.Protocol = C.ProtocolBitTorrent
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return nil
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}
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// UTP detects if the packet is a uTP connection packet.
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// For the uTP protocol specification, see
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// 1. https://www.bittorrent.org/beps/bep_0029.html
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// 2. https://github.com/bittorrent/libutp/blob/2b364cbb0650bdab64a5de2abb4518f9f228ec44/utp_internal.cpp#L112
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func UTP(_ context.Context, metadata *adapter.InboundContext, packet []byte) error {
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// A valid uTP packet must be at least 20 bytes long.
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if len(packet) < 20 {
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return os.ErrInvalid
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}
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version := packet[0] & 0x0F
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ty := packet[0] >> 4
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if version != 1 || ty > 4 {
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return os.ErrInvalid
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}
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// Validate the extensions
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extension := packet[1]
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reader := bytes.NewReader(packet[20:])
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for extension != 0 {
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err := binary.Read(reader, binary.BigEndian, &extension)
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if err != nil {
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return err
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}
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var length byte
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err = binary.Read(reader, binary.BigEndian, &length)
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if err != nil {
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return err
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}
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_, err = reader.Seek(int64(length), io.SeekCurrent)
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if err != nil {
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return err
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}
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}
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metadata.Protocol = C.ProtocolBitTorrent
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return nil
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}
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// UDPTracker detects if the packet is a UDP Tracker Protocol packet.
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// For the UDP Tracker Protocol specification, see https://www.bittorrent.org/beps/bep_0015.html
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func UDPTracker(_ context.Context, metadata *adapter.InboundContext, packet []byte) error {
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if len(packet) < trackerConnectMinSize {
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return os.ErrInvalid
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}
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if binary.BigEndian.Uint64(packet[:8]) != trackerProtocolID {
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return os.ErrInvalid
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}
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if binary.BigEndian.Uint32(packet[8:12]) != trackerConnectFlag {
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return os.ErrInvalid
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}
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metadata.Protocol = C.ProtocolBitTorrent
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return nil
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}
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