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header.go
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header.go
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package wire
import (
"bytes"
"errors"
"io"
"v2ray.com/core/external/github.com/lucas-clemente/quic-go/internal/protocol"
"v2ray.com/core/external/github.com/lucas-clemente/quic-go/internal/qerr"
"v2ray.com/core/external/github.com/lucas-clemente/quic-go/internal/utils"
)
// The Header is the version independent part of the header
type Header struct {
Version protocol.VersionNumber
SrcConnectionID protocol.ConnectionID
DestConnectionID protocol.ConnectionID
IsLongHeader bool
Type protocol.PacketType
Length protocol.ByteCount
Token []byte
SupportedVersions []protocol.VersionNumber // sent in a Version Negotiation Packet
OrigDestConnectionID protocol.ConnectionID // sent in the Retry packet
typeByte byte
parsedLen protocol.ByteCount // how many bytes were read while parsing this header
}
// ParseHeader parses the header.
// For short header packets: up to the packet number.
// For long header packets:
// * if we understand the version: up to the packet number
// * if not, only the invariant part of the header
func ParseHeader(b *bytes.Reader, shortHeaderConnIDLen int) (*Header, error) {
startLen := b.Len()
h, err := parseHeaderImpl(b, shortHeaderConnIDLen)
if err != nil {
return nil, err
}
h.parsedLen = protocol.ByteCount(startLen - b.Len())
return h, nil
}
func parseHeaderImpl(b *bytes.Reader, shortHeaderConnIDLen int) (*Header, error) {
typeByte, err := b.ReadByte()
if err != nil {
return nil, err
}
h := &Header{
typeByte: typeByte,
IsLongHeader: typeByte&0x80 > 0,
}
if !h.IsLongHeader {
if h.typeByte&0x40 == 0 {
return nil, errors.New("not a QUIC packet")
}
if err := h.parseShortHeader(b, shortHeaderConnIDLen); err != nil {
return nil, err
}
return h, nil
}
if err := h.parseLongHeader(b); err != nil {
return nil, err
}
return h, nil
}
func (h *Header) parseShortHeader(b *bytes.Reader, shortHeaderConnIDLen int) error {
var err error
h.DestConnectionID, err = protocol.ReadConnectionID(b, shortHeaderConnIDLen)
return err
}
func (h *Header) parseLongHeader(b *bytes.Reader) error {
v, err := utils.BigEndian.ReadUint32(b)
if err != nil {
return err
}
h.Version = protocol.VersionNumber(v)
if !h.IsVersionNegotiation() && h.typeByte&0x40 == 0 {
return errors.New("not a QUIC packet")
}
connIDLenByte, err := b.ReadByte()
if err != nil {
return err
}
dcil, scil := decodeConnIDLen(connIDLenByte)
h.DestConnectionID, err = protocol.ReadConnectionID(b, dcil)
if err != nil {
return err
}
h.SrcConnectionID, err = protocol.ReadConnectionID(b, scil)
if err != nil {
return err
}
if h.Version == 0 {
return h.parseVersionNegotiationPacket(b)
}
// If we don't understand the version, we have no idea how to interpret the rest of the bytes
if !protocol.IsSupportedVersion(protocol.SupportedVersions, h.Version) {
return nil
}
switch (h.typeByte & 0x30) >> 4 {
case 0x0:
h.Type = protocol.PacketTypeInitial
case 0x1:
h.Type = protocol.PacketType0RTT
case 0x2:
h.Type = protocol.PacketTypeHandshake
case 0x3:
h.Type = protocol.PacketTypeRetry
}
if h.Type == protocol.PacketTypeRetry {
odcil := decodeSingleConnIDLen(h.typeByte & 0xf)
h.OrigDestConnectionID, err = protocol.ReadConnectionID(b, odcil)
if err != nil {
return err
}
h.Token = make([]byte, b.Len())
if _, err := io.ReadFull(b, h.Token); err != nil {
return err
}
return nil
}
if h.Type == protocol.PacketTypeInitial {
tokenLen, err := utils.ReadVarInt(b)
if err != nil {
return err
}
if tokenLen > uint64(b.Len()) {
return io.EOF
}
h.Token = make([]byte, tokenLen)
if _, err := io.ReadFull(b, h.Token); err != nil {
return err
}
}
pl, err := utils.ReadVarInt(b)
if err != nil {
return err
}
h.Length = protocol.ByteCount(pl)
return nil
}
func (h *Header) parseVersionNegotiationPacket(b *bytes.Reader) error {
if b.Len() == 0 {
return qerr.Error(qerr.InvalidVersionNegotiationPacket, "empty version list")
}
h.SupportedVersions = make([]protocol.VersionNumber, b.Len()/4)
for i := 0; b.Len() > 0; i++ {
v, err := utils.BigEndian.ReadUint32(b)
if err != nil {
return qerr.InvalidVersionNegotiationPacket
}
h.SupportedVersions[i] = protocol.VersionNumber(v)
}
return nil
}
// IsVersionNegotiation says if this a version negotiation packet
func (h *Header) IsVersionNegotiation() bool {
return h.IsLongHeader && h.Version == 0
}
// ParsedLen returns the number of bytes that were consumed when parsing the header
func (h *Header) ParsedLen() protocol.ByteCount {
return h.parsedLen
}
// ParseExtended parses the version dependent part of the header.
// The Reader has to be set such that it points to the first byte of the header.
func (h *Header) ParseExtended(b *bytes.Reader, ver protocol.VersionNumber) (*ExtendedHeader, error) {
return h.toExtendedHeader().parse(b, ver)
}
func (h *Header) toExtendedHeader() *ExtendedHeader {
return &ExtendedHeader{Header: *h}
}
func decodeConnIDLen(enc byte) (int /*dest conn id len*/, int /*src conn id len*/) {
return decodeSingleConnIDLen(enc >> 4), decodeSingleConnIDLen(enc & 0xf)
}
func decodeSingleConnIDLen(enc uint8) int {
if enc == 0 {
return 0
}
return int(enc) + 3
}