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package wire
import (
"errors"
"io"
"github.com/quic-go/quic-go/internal/protocol"
"github.com/quic-go/quic-go/internal/utils"
)
// ParseShortHeader parses a short header packet.
// It must be called after header protection was removed.
// Otherwise, the check for the reserved bits will (most likely) fail.
func ParseShortHeader(data []byte, connIDLen int) (length int, _ protocol.PacketNumber, _ protocol.PacketNumberLen, _ protocol.KeyPhaseBit, _ error) {
if len(data) == 0 {
return 0, 0, 0, 0, io.EOF
}
if data[0]&0x80 > 0 {
return 0, 0, 0, 0, errors.New("not a short header packet")
}
if data[0]&0x40 == 0 {
return 0, 0, 0, 0, errors.New("not a QUIC packet")
}
pnLen := protocol.PacketNumberLen(data[0]&0b11) + 1
if len(data) < 1+int(pnLen)+connIDLen {
return 0, 0, 0, 0, io.EOF
}
pos := 1 + connIDLen
pn, err := readPacketNumber(data[pos:], pnLen)
if err != nil {
return 0, 0, 0, 0, err
}
kp := protocol.KeyPhaseZero
if data[0]&0b100 > 0 {
kp = protocol.KeyPhaseOne
}
if data[0]&0x18 != 0 {
err = ErrInvalidReservedBits
}
return 1 + connIDLen + int(pnLen), pn, pnLen, kp, err
}
// AppendShortHeader writes a short header.
func AppendShortHeader(b []byte, connID protocol.ConnectionID, pn protocol.PacketNumber, pnLen protocol.PacketNumberLen, kp protocol.KeyPhaseBit) ([]byte, error) {
typeByte := 0x40 | uint8(pnLen-1)
if kp == protocol.KeyPhaseOne {
typeByte |= byte(1 << 2)
}
b = append(b, typeByte)
b = append(b, connID.Bytes()...)
return appendPacketNumber(b, pn, pnLen)
}
func ShortHeaderLen(dest protocol.ConnectionID, pnLen protocol.PacketNumberLen) protocol.ByteCount {
return 1 + protocol.ByteCount(dest.Len()) + protocol.ByteCount(pnLen)
}
func LogShortHeader(logger utils.Logger, dest protocol.ConnectionID, pn protocol.PacketNumber, pnLen protocol.PacketNumberLen, kp protocol.KeyPhaseBit) {
logger.Debugf("\tShort Header{DestConnectionID: %s, PacketNumber: %d, PacketNumberLen: %d, KeyPhase: %s}", dest, pn, pnLen, kp)
}
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