status-go/vendor/github.com/lucas-clemente/quic-go/internal/wire/stream_frame.go

190 lines
4.7 KiB
Go

package wire
import (
"bytes"
"errors"
"io"
"github.com/lucas-clemente/quic-go/internal/protocol"
"github.com/lucas-clemente/quic-go/quicvarint"
)
// A StreamFrame of QUIC
type StreamFrame struct {
StreamID protocol.StreamID
Offset protocol.ByteCount
Data []byte
Fin bool
DataLenPresent bool
fromPool bool
}
func parseStreamFrame(r *bytes.Reader, _ protocol.VersionNumber) (*StreamFrame, error) {
typeByte, err := r.ReadByte()
if err != nil {
return nil, err
}
hasOffset := typeByte&0x4 > 0
fin := typeByte&0x1 > 0
hasDataLen := typeByte&0x2 > 0
streamID, err := quicvarint.Read(r)
if err != nil {
return nil, err
}
var offset uint64
if hasOffset {
offset, err = quicvarint.Read(r)
if err != nil {
return nil, err
}
}
var dataLen uint64
if hasDataLen {
var err error
dataLen, err = quicvarint.Read(r)
if err != nil {
return nil, err
}
} else {
// The rest of the packet is data
dataLen = uint64(r.Len())
}
var frame *StreamFrame
if dataLen < protocol.MinStreamFrameBufferSize {
frame = &StreamFrame{Data: make([]byte, dataLen)}
} else {
frame = GetStreamFrame()
// The STREAM frame can't be larger than the StreamFrame we obtained from the buffer,
// since those StreamFrames have a buffer length of the maximum packet size.
if dataLen > uint64(cap(frame.Data)) {
return nil, io.EOF
}
frame.Data = frame.Data[:dataLen]
}
frame.StreamID = protocol.StreamID(streamID)
frame.Offset = protocol.ByteCount(offset)
frame.Fin = fin
frame.DataLenPresent = hasDataLen
if dataLen != 0 {
if _, err := io.ReadFull(r, frame.Data); err != nil {
return nil, err
}
}
if frame.Offset+frame.DataLen() > protocol.MaxByteCount {
return nil, errors.New("stream data overflows maximum offset")
}
return frame, nil
}
// Write writes a STREAM frame
func (f *StreamFrame) Write(b *bytes.Buffer, version protocol.VersionNumber) error {
if len(f.Data) == 0 && !f.Fin {
return errors.New("StreamFrame: attempting to write empty frame without FIN")
}
typeByte := byte(0x8)
if f.Fin {
typeByte ^= 0x1
}
hasOffset := f.Offset != 0
if f.DataLenPresent {
typeByte ^= 0x2
}
if hasOffset {
typeByte ^= 0x4
}
b.WriteByte(typeByte)
quicvarint.Write(b, uint64(f.StreamID))
if hasOffset {
quicvarint.Write(b, uint64(f.Offset))
}
if f.DataLenPresent {
quicvarint.Write(b, uint64(f.DataLen()))
}
b.Write(f.Data)
return nil
}
// Length returns the total length of the STREAM frame
func (f *StreamFrame) Length(version protocol.VersionNumber) protocol.ByteCount {
length := 1 + quicvarint.Len(uint64(f.StreamID))
if f.Offset != 0 {
length += quicvarint.Len(uint64(f.Offset))
}
if f.DataLenPresent {
length += quicvarint.Len(uint64(f.DataLen()))
}
return length + f.DataLen()
}
// DataLen gives the length of data in bytes
func (f *StreamFrame) DataLen() protocol.ByteCount {
return protocol.ByteCount(len(f.Data))
}
// MaxDataLen returns the maximum data length
// If 0 is returned, writing will fail (a STREAM frame must contain at least 1 byte of data).
func (f *StreamFrame) MaxDataLen(maxSize protocol.ByteCount, version protocol.VersionNumber) protocol.ByteCount {
headerLen := 1 + quicvarint.Len(uint64(f.StreamID))
if f.Offset != 0 {
headerLen += quicvarint.Len(uint64(f.Offset))
}
if f.DataLenPresent {
// pretend that the data size will be 1 bytes
// if it turns out that varint encoding the length will consume 2 bytes, we need to adjust the data length afterwards
headerLen++
}
if headerLen > maxSize {
return 0
}
maxDataLen := maxSize - headerLen
if f.DataLenPresent && quicvarint.Len(uint64(maxDataLen)) != 1 {
maxDataLen--
}
return maxDataLen
}
// MaybeSplitOffFrame splits a frame such that it is not bigger than n bytes.
// It returns if the frame was actually split.
// The frame might not be split if:
// * the size is large enough to fit the whole frame
// * the size is too small to fit even a 1-byte frame. In that case, the frame returned is nil.
func (f *StreamFrame) MaybeSplitOffFrame(maxSize protocol.ByteCount, version protocol.VersionNumber) (*StreamFrame, bool /* was splitting required */) {
if maxSize >= f.Length(version) {
return nil, false
}
n := f.MaxDataLen(maxSize, version)
if n == 0 {
return nil, true
}
new := GetStreamFrame()
new.StreamID = f.StreamID
new.Offset = f.Offset
new.Fin = false
new.DataLenPresent = f.DataLenPresent
// swap the data slices
new.Data, f.Data = f.Data, new.Data
new.fromPool, f.fromPool = f.fromPool, new.fromPool
f.Data = f.Data[:protocol.ByteCount(len(new.Data))-n]
copy(f.Data, new.Data[n:])
new.Data = new.Data[:n]
f.Offset += n
return new, true
}
func (f *StreamFrame) PutBack() {
putStreamFrame(f)
}