133 lines
3.2 KiB
Go
133 lines
3.2 KiB
Go
package wire
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import (
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"bytes"
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"errors"
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"io"
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"github.com/lucas-clemente/quic-go/internal/protocol"
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"github.com/lucas-clemente/quic-go/internal/utils"
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"github.com/lucas-clemente/quic-go/qerr"
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)
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// A StreamFrame of QUIC
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type StreamFrame struct {
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StreamID protocol.StreamID
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FinBit bool
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DataLenPresent bool
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Offset protocol.ByteCount
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Data []byte
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}
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// ParseStreamFrame reads a STREAM frame
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func ParseStreamFrame(r *bytes.Reader, version protocol.VersionNumber) (*StreamFrame, error) {
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if !version.UsesIETFFrameFormat() {
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return parseLegacyStreamFrame(r, version)
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}
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frame := &StreamFrame{}
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typeByte, err := r.ReadByte()
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if err != nil {
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return nil, err
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}
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frame.FinBit = typeByte&0x1 > 0
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frame.DataLenPresent = typeByte&0x2 > 0
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hasOffset := typeByte&0x4 > 0
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streamID, err := utils.ReadVarInt(r)
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if err != nil {
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return nil, err
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}
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frame.StreamID = protocol.StreamID(streamID)
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if hasOffset {
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offset, err := utils.ReadVarInt(r)
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if err != nil {
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return nil, err
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}
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frame.Offset = protocol.ByteCount(offset)
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}
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var dataLen uint64
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if frame.DataLenPresent {
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var err error
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dataLen, err = utils.ReadVarInt(r)
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if err != nil {
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return nil, err
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}
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// shortcut to prevent the unneccessary allocation of dataLen bytes
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// if the dataLen is larger than the remaining length of the packet
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// reading the packet contents would result in EOF when attempting to READ
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if dataLen > uint64(r.Len()) {
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return nil, io.EOF
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}
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} else {
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// The rest of the packet is data
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dataLen = uint64(r.Len())
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}
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if dataLen != 0 {
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frame.Data = make([]byte, dataLen)
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if _, err := io.ReadFull(r, frame.Data); err != nil {
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// this should never happen, since we already checked the dataLen earlier
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return nil, err
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}
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}
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if frame.Offset+frame.DataLen() > protocol.MaxByteCount {
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return nil, qerr.Error(qerr.InvalidStreamData, "data overflows maximum offset")
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}
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if !frame.FinBit && frame.DataLen() == 0 {
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return nil, qerr.EmptyStreamFrameNoFin
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}
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return frame, nil
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}
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// Write writes a STREAM frame
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func (f *StreamFrame) Write(b *bytes.Buffer, version protocol.VersionNumber) error {
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if !version.UsesIETFFrameFormat() {
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return f.writeLegacy(b, version)
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}
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if len(f.Data) == 0 && !f.FinBit {
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return errors.New("StreamFrame: attempting to write empty frame without FIN")
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}
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typeByte := byte(0x10)
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if f.FinBit {
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typeByte ^= 0x1
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}
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hasOffset := f.Offset != 0
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if f.DataLenPresent {
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typeByte ^= 0x2
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}
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if hasOffset {
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typeByte ^= 0x4
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}
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b.WriteByte(typeByte)
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utils.WriteVarInt(b, uint64(f.StreamID))
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if hasOffset {
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utils.WriteVarInt(b, uint64(f.Offset))
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}
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if f.DataLenPresent {
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utils.WriteVarInt(b, uint64(f.DataLen()))
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}
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b.Write(f.Data)
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return nil
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}
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// MinLength returns the length of the header of a StreamFrame
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// the total length of the frame is frame.MinLength() + frame.DataLen()
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func (f *StreamFrame) MinLength(version protocol.VersionNumber) protocol.ByteCount {
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if !version.UsesIETFFrameFormat() {
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return f.minLengthLegacy(version)
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}
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length := 1 + utils.VarIntLen(uint64(f.StreamID))
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if f.Offset != 0 {
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length += utils.VarIntLen(uint64(f.Offset))
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}
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if f.DataLenPresent {
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length += utils.VarIntLen(uint64(f.DataLen()))
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}
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return length
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}
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