forked from quic-go/quic-go
/
stream_frame_legacy.go
209 lines (182 loc) · 5.01 KB
/
stream_frame_legacy.go
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package wire
import (
"bytes"
"errors"
"io"
"github.com/lucas-clemente/quic-go/internal/protocol"
"github.com/lucas-clemente/quic-go/internal/utils"
"github.com/lucas-clemente/quic-go/qerr"
)
var (
errInvalidStreamIDLen = errors.New("StreamFrame: Invalid StreamID length")
errInvalidOffsetLen = errors.New("StreamFrame: Invalid offset length")
)
// parseLegacyStreamFrame reads a stream frame. The type byte must not have been read yet.
func parseLegacyStreamFrame(r *bytes.Reader, _ protocol.VersionNumber) (*StreamFrame, error) {
frame := &StreamFrame{}
typeByte, err := r.ReadByte()
if err != nil {
return nil, err
}
frame.FinBit = typeByte&0x40 > 0
frame.DataLenPresent = typeByte&0x20 > 0
offsetLen := typeByte & 0x1c >> 2
if offsetLen != 0 {
offsetLen++
}
streamIDLen := typeByte&0x3 + 1
sid, err := utils.BigEndian.ReadUintN(r, streamIDLen)
if err != nil {
return nil, err
}
frame.StreamID = protocol.StreamID(sid)
offset, err := utils.BigEndian.ReadUintN(r, offsetLen)
if err != nil {
return nil, err
}
frame.Offset = protocol.ByteCount(offset)
var dataLen uint16
if frame.DataLenPresent {
dataLen, err = utils.BigEndian.ReadUint16(r)
if err != nil {
return nil, err
}
}
// shortcut to prevent the unnecessary allocation of dataLen bytes
// if the dataLen is larger than the remaining length of the packet
// reading the packet contents would result in EOF when attempting to READ
if int(dataLen) > r.Len() {
return nil, io.EOF
}
if !frame.DataLenPresent {
// The rest of the packet is data
dataLen = uint16(r.Len())
}
if dataLen != 0 {
frame.Data = make([]byte, dataLen)
if _, err := io.ReadFull(r, frame.Data); err != nil {
// this should never happen, since we already checked the dataLen earlier
return nil, err
}
}
// MaxByteCount is the highest value that can be encoded with the IETF QUIC variable integer encoding (2^62-1).
// Note that this value is smaller than the maximum value that could be encoded in the gQUIC STREAM frame (2^64-1).
if frame.Offset+frame.DataLen() > protocol.MaxByteCount {
return nil, qerr.Error(qerr.InvalidStreamData, "data overflows maximum offset")
}
if !frame.FinBit && frame.DataLen() == 0 {
return nil, qerr.EmptyStreamFrameNoFin
}
return frame, nil
}
// writeLegacy writes a stream frame.
func (f *StreamFrame) writeLegacy(b *bytes.Buffer, _ protocol.VersionNumber) error {
if len(f.Data) == 0 && !f.FinBit {
return errors.New("StreamFrame: attempting to write empty frame without FIN")
}
typeByte := uint8(0x80) // sets the leftmost bit to 1
if f.FinBit {
typeByte ^= 0x40
}
if f.DataLenPresent {
typeByte ^= 0x20
}
offsetLength := f.getOffsetLength()
if offsetLength > 0 {
typeByte ^= (uint8(offsetLength) - 1) << 2
}
streamIDLen := f.calculateStreamIDLength()
typeByte ^= streamIDLen - 1
b.WriteByte(typeByte)
switch streamIDLen {
case 1:
b.WriteByte(uint8(f.StreamID))
case 2:
utils.BigEndian.WriteUint16(b, uint16(f.StreamID))
case 3:
utils.BigEndian.WriteUint24(b, uint32(f.StreamID))
case 4:
utils.BigEndian.WriteUint32(b, uint32(f.StreamID))
default:
return errInvalidStreamIDLen
}
switch offsetLength {
case 0:
case 2:
utils.BigEndian.WriteUint16(b, uint16(f.Offset))
case 3:
utils.BigEndian.WriteUint24(b, uint32(f.Offset))
case 4:
utils.BigEndian.WriteUint32(b, uint32(f.Offset))
case 5:
utils.BigEndian.WriteUint40(b, uint64(f.Offset))
case 6:
utils.BigEndian.WriteUint48(b, uint64(f.Offset))
case 7:
utils.BigEndian.WriteUint56(b, uint64(f.Offset))
case 8:
utils.BigEndian.WriteUint64(b, uint64(f.Offset))
default:
return errInvalidOffsetLen
}
if f.DataLenPresent {
utils.BigEndian.WriteUint16(b, uint16(len(f.Data)))
}
b.Write(f.Data)
return nil
}
func (f *StreamFrame) calculateStreamIDLength() uint8 {
if f.StreamID < (1 << 8) {
return 1
} else if f.StreamID < (1 << 16) {
return 2
} else if f.StreamID < (1 << 24) {
return 3
}
return 4
}
func (f *StreamFrame) getOffsetLength() protocol.ByteCount {
if f.Offset == 0 {
return 0
}
if f.Offset < (1 << 16) {
return 2
}
if f.Offset < (1 << 24) {
return 3
}
if f.Offset < (1 << 32) {
return 4
}
if f.Offset < (1 << 40) {
return 5
}
if f.Offset < (1 << 48) {
return 6
}
if f.Offset < (1 << 56) {
return 7
}
return 8
}
func (f *StreamFrame) headerLengthLegacy(_ protocol.VersionNumber) protocol.ByteCount {
length := protocol.ByteCount(1) + protocol.ByteCount(f.calculateStreamIDLength()) + f.getOffsetLength()
if f.DataLenPresent {
length += 2
}
return length
}
func (f *StreamFrame) lengthLegacy(version protocol.VersionNumber) protocol.ByteCount {
return f.headerLengthLegacy(version) + f.DataLen()
}
func (f *StreamFrame) maxDataLenLegacy(maxFrameSize protocol.ByteCount, version protocol.VersionNumber) protocol.ByteCount {
headerLen := f.headerLengthLegacy(version)
if headerLen > maxFrameSize {
return 0
}
return maxFrameSize - headerLen
}
// DataLen gives the length of data in bytes
func (f *StreamFrame) DataLen() protocol.ByteCount {
return protocol.ByteCount(len(f.Data))
}