76 lines
1.9 KiB
Go
76 lines
1.9 KiB
Go
package protocol
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import (
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"bytes"
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"errors"
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"fmt"
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"math/rand"
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"net"
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)
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var (
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errAuthSHA1V4CRC32Error = errors.New("auth_sha1_v4 decode data wrong crc32")
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errAuthSHA1V4LengthError = errors.New("auth_sha1_v4 decode data wrong length")
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errAuthSHA1V4Adler32Error = errors.New("auth_sha1_v4 decode data wrong adler32")
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errAuthAES128MACError = errors.New("auth_aes128 decode data wrong mac")
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errAuthAES128LengthError = errors.New("auth_aes128 decode data wrong length")
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errAuthAES128ChksumError = errors.New("auth_aes128 decode data wrong checksum")
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errAuthChainLengthError = errors.New("auth_chain decode data wrong length")
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errAuthChainChksumError = errors.New("auth_chain decode data wrong checksum")
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)
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type Protocol interface {
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StreamConn(net.Conn, []byte) net.Conn
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PacketConn(net.PacketConn) net.PacketConn
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Decode(dst, src *bytes.Buffer) error
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Encode(buf *bytes.Buffer, b []byte) error
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DecodePacket([]byte) ([]byte, error)
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EncodePacket(buf *bytes.Buffer, b []byte) error
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}
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type protocolCreator func(b *Base) Protocol
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var protocolList = make(map[string]struct {
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overhead int
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new protocolCreator
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})
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func register(name string, c protocolCreator, o int) {
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protocolList[name] = struct {
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overhead int
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new protocolCreator
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}{overhead: o, new: c}
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}
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func PickProtocol(name string, b *Base) (Protocol, error) {
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if choice, ok := protocolList[name]; ok {
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b.Overhead += choice.overhead
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return choice.new(b), nil
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}
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return nil, fmt.Errorf("protocol %s not supported", name)
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}
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func getHeadSize(b []byte, defaultValue int) int {
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if len(b) < 2 {
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return defaultValue
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}
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headType := b[0] & 7
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switch headType {
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case 1:
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return 7
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case 4:
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return 19
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case 3:
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return 4 + int(b[1])
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}
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return defaultValue
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}
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func getDataLength(b []byte) int {
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bLength := len(b)
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dataLength := getHeadSize(b, 30) + rand.Intn(32)
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if bLength < dataLength {
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return bLength
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}
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return dataLength
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}
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