github.com/laof/lite-speed-test@v0.0.0-20230930011949-1f39b7037845/transport/ssr/protocol/protocol.go (about)

     1  package protocol
     2  
     3  import (
     4  	"bytes"
     5  	"errors"
     6  	"fmt"
     7  	"math/rand"
     8  	"net"
     9  )
    10  
    11  var (
    12  	errAuthSHA1V4CRC32Error   = errors.New("auth_sha1_v4 decode data wrong crc32")
    13  	errAuthSHA1V4LengthError  = errors.New("auth_sha1_v4 decode data wrong length")
    14  	errAuthSHA1V4Adler32Error = errors.New("auth_sha1_v4 decode data wrong adler32")
    15  	errAuthAES128MACError     = errors.New("auth_aes128 decode data wrong mac")
    16  	errAuthAES128LengthError  = errors.New("auth_aes128 decode data wrong length")
    17  	errAuthAES128ChksumError  = errors.New("auth_aes128 decode data wrong checksum")
    18  	errAuthChainLengthError   = errors.New("auth_chain decode data wrong length")
    19  	errAuthChainChksumError   = errors.New("auth_chain decode data wrong checksum")
    20  )
    21  
    22  type Protocol interface {
    23  	StreamConn(net.Conn, []byte) net.Conn
    24  	PacketConn(net.PacketConn) net.PacketConn
    25  	Decode(dst, src *bytes.Buffer) error
    26  	Encode(buf *bytes.Buffer, b []byte) error
    27  	DecodePacket([]byte) ([]byte, error)
    28  	EncodePacket(buf *bytes.Buffer, b []byte) error
    29  }
    30  
    31  type protocolCreator func(b *Base) Protocol
    32  
    33  var protocolList = make(map[string]struct {
    34  	overhead int
    35  	new      protocolCreator
    36  })
    37  
    38  func register(name string, c protocolCreator, o int) {
    39  	protocolList[name] = struct {
    40  		overhead int
    41  		new      protocolCreator
    42  	}{overhead: o, new: c}
    43  }
    44  
    45  func PickProtocol(name string, b *Base) (Protocol, error) {
    46  	if choice, ok := protocolList[name]; ok {
    47  		b.Overhead += choice.overhead
    48  		return choice.new(b), nil
    49  	}
    50  	return nil, fmt.Errorf("protocol %s not supported", name)
    51  }
    52  
    53  func getHeadSize(b []byte, defaultValue int) int {
    54  	if len(b) < 2 {
    55  		return defaultValue
    56  	}
    57  	headType := b[0] & 7
    58  	switch headType {
    59  	case 1:
    60  		return 7
    61  	case 4:
    62  		return 19
    63  	case 3:
    64  		return 4 + int(b[1])
    65  	}
    66  	return defaultValue
    67  }
    68  
    69  func getDataLength(b []byte) int {
    70  	bLength := len(b)
    71  	dataLength := getHeadSize(b, 30) + rand.Intn(32)
    72  	if bLength < dataLength {
    73  		return bLength
    74  	}
    75  	return dataLength
    76  }