Golang Buffer.Slice方法代码示例

func (this *SimpleAuthenticator) Open(buffer *alloc.Buffer) bool {
	len := buffer.Len()
	xtra := 4 - len%4
	if xtra != 0 {
		buffer.Slice(0, len+xtra)
	}
	xorbkd(buffer.Value)
	if xtra != 0 {
		buffer.Slice(0, len)
	}

	fnvHash := fnv.New32a()
	fnvHash.Write(buffer.Value[4:])
	if serial.BytesToUint32(buffer.Value[:4]) != fnvHash.Sum32() {
		return false
	}

	length := serial.BytesToUint16(buffer.Value[4:6])
	if buffer.Len()-6 != int(length) {
		return false
	}

	buffer.SliceFrom(6)

	return true
}

func ReadFrom(reader io.Reader, buffer *alloc.Buffer) (*alloc.Buffer, error) {
	if buffer == nil {
		buffer = alloc.NewBuffer()
	}
	nBytes, err := reader.Read(buffer.Value)
	buffer.Slice(0, nBytes)
	return buffer, err
}

// ToBytes returns a VMessRequest in the form of byte array.
func (this *VMessRequest) ToBytes(timestampGenerator RandomTimestampGenerator, buffer *alloc.Buffer) (*alloc.Buffer, error) {
	if buffer == nil {
		buffer = alloc.NewSmallBuffer().Clear()
	}

	timestamp := timestampGenerator.Next()
	idHash := IDHash(this.User.AnyValidID().Bytes())
	idHash.Write(timestamp.Bytes())

	hashStart := buffer.Len()
	buffer.Slice(0, hashStart+16)
	idHash.Sum(buffer.Value[hashStart:hashStart])

	encryptionBegin := buffer.Len()

	buffer.AppendBytes(this.Version)
	buffer.Append(this.RequestIV)
	buffer.Append(this.RequestKey)
	buffer.AppendBytes(this.ResponseHeader, this.Option, byte(0), byte(0))
	buffer.AppendBytes(this.Command)
	buffer.Append(this.Port.Bytes())

	switch {
	case this.Address.IsIPv4():
		buffer.AppendBytes(addrTypeIPv4)
		buffer.Append(this.Address.IP())
	case this.Address.IsIPv6():
		buffer.AppendBytes(addrTypeIPv6)
		buffer.Append(this.Address.IP())
	case this.Address.IsDomain():
		buffer.AppendBytes(addrTypeDomain, byte(len(this.Address.Domain())))
		buffer.Append([]byte(this.Address.Domain()))
	}

	encryptionEnd := buffer.Len()

	fnv1a := fnv.New32a()
	fnv1a.Write(buffer.Value[encryptionBegin:encryptionEnd])

	fnvHash := fnv1a.Sum32()
	buffer.AppendBytes(byte(fnvHash>>24), byte(fnvHash>>16), byte(fnvHash>>8), byte(fnvHash))
	encryptionEnd += 4

	timestampHash := md5.New()
	timestampHash.Write(timestamp.HashBytes())
	iv := timestampHash.Sum(nil)
	aesStream, err := v2crypto.NewAesEncryptionStream(this.User.ID.CmdKey(), iv)
	if err != nil {
		return nil, err
	}
	aesStream.XORKeyStream(buffer.Value[encryptionBegin:encryptionEnd], buffer.Value[encryptionBegin:encryptionEnd])

	return buffer, nil
}

func (this *SimpleAuthenticator) Seal(buffer *alloc.Buffer) {
	buffer.PrependUint16(uint16(buffer.Len()))
	fnvHash := fnv.New32a()
	fnvHash.Write(buffer.Value)
	buffer.PrependHash(fnvHash)

	len := buffer.Len()
	xtra := 4 - len%4
	if xtra != 0 {
		buffer.Slice(0, len+xtra)
	}
	xorfwd(buffer.Value)
	if xtra != 0 {
		buffer.Slice(0, len)
	}
}

func (this *AuthChunkReader) Read() (*alloc.Buffer, error) {
	var buffer *alloc.Buffer
	if this.last != nil {
		buffer = this.last
		this.last = nil
	} else {
		buffer = alloc.NewBufferWithSize(4096).Clear()
	}

	if this.chunkLength == -1 {
		for buffer.Len() < 6 {
			_, err := buffer.FillFrom(this.reader)
			if err != nil {
				buffer.Release()
				return nil, io.ErrUnexpectedEOF
			}
		}
		length := serial.BytesToUint16(buffer.Value[:2])
		this.chunkLength = int(length) - 4
		this.validator = NewValidator(serial.BytesToUint32(buffer.Value[2:6]))
		buffer.SliceFrom(6)
		if buffer.Len() < this.chunkLength && this.chunkLength <= 2048 {
			_, err := buffer.FillFrom(this.reader)
			if err != nil {
				buffer.Release()
				return nil, io.ErrUnexpectedEOF
			}
		}
	} else if buffer.Len() < this.chunkLength {
		_, err := buffer.FillFrom(this.reader)
		if err != nil {
			buffer.Release()
			return nil, io.ErrUnexpectedEOF
		}
	}

	if this.chunkLength == 0 {
		buffer.Release()
		return nil, io.EOF
	}

	if buffer.Len() < this.chunkLength {
		this.validator.Consume(buffer.Value)
		this.chunkLength -= buffer.Len()
	} else {
		this.validator.Consume(buffer.Value[:this.chunkLength])
		if !this.validator.Validate() {
			buffer.Release()
			return nil, transport.ErrCorruptedPacket
		}
		leftLength := buffer.Len() - this.chunkLength
		if leftLength > 0 {
			this.last = alloc.NewBufferWithSize(leftLength + 4096).Clear()
			this.last.Append(buffer.Value[this.chunkLength:])
			buffer.Slice(0, this.chunkLength)
		}

		this.chunkLength = -1
		this.validator = nil
	}

	return buffer, nil
}