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package http3
import (
"io"
"github.com/quic-go/quic-go/quicvarint"
)
// CapsuleType is the type of the capsule
type CapsuleType uint64
// CapsuleProtocolHeader is the header value used to advertise support for the capsule protocol
const CapsuleProtocolHeader = "Capsule-Protocol"
type exactReader struct {
R io.LimitedReader
}
func (r *exactReader) Read(b []byte) (int, error) {
n, err := r.R.Read(b)
if err == io.EOF && r.R.N > 0 {
return n, io.ErrUnexpectedEOF
}
return n, err
}
type countingByteReader struct {
io.ByteReader
Read int
}
func (r *countingByteReader) ReadByte() (byte, error) {
b, err := r.ByteReader.ReadByte()
if err == nil {
r.Read++
}
return b, err
}
// ParseCapsule parses the header of a Capsule.
// It returns an io.Reader that can be used to read the Capsule value.
// The Capsule value must be read entirely (i.e. until the io.EOF) before using r again.
func ParseCapsule(r quicvarint.Reader) (CapsuleType, io.Reader, error) {
cbr := countingByteReader{ByteReader: r}
ct, err := quicvarint.Read(&cbr)
if err != nil {
// If an io.EOF is returned without consuming any bytes, return it unmodified.
// Otherwise, return an io.ErrUnexpectedEOF.
if err == io.EOF && cbr.Read > 0 {
return 0, nil, io.ErrUnexpectedEOF
}
return 0, nil, err
}
l, err := quicvarint.Read(r)
if err != nil {
if err == io.EOF {
return 0, nil, io.ErrUnexpectedEOF
}
return 0, nil, err
}
return CapsuleType(ct), &exactReader{R: io.LimitedReader{R: r, N: int64(l)}}, nil
}
// WriteCapsule writes a capsule
func WriteCapsule(w quicvarint.Writer, ct CapsuleType, value []byte) error {
b := make([]byte, 0, 16)
b = quicvarint.Append(b, uint64(ct))
b = quicvarint.Append(b, uint64(len(value)))
if _, err := w.Write(b); err != nil {
return err
}
_, err := w.Write(value)
return err
}
|
