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frame_parser.go
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/
frame_parser.go
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package wire
import (
"bytes"
"errors"
"fmt"
"reflect"
"github.com/lucas-clemente/quic-go/internal/protocol"
"github.com/lucas-clemente/quic-go/internal/qerr"
)
type frameParser struct {
r *bytes.Reader // cached bytes.Reader, so we don't have to repeatedly allocate them
ackDelayExponent uint8
supportsDatagrams bool
version protocol.VersionNumber
}
// NewFrameParser creates a new frame parser.
func NewFrameParser(supportsDatagrams bool, v protocol.VersionNumber) FrameParser {
return &frameParser{
r: bytes.NewReader(nil),
supportsDatagrams: supportsDatagrams,
version: v,
}
}
// ParseNext parses the next frame.
// It skips PADDING frames.
func (p *frameParser) ParseNext(data []byte, encLevel protocol.EncryptionLevel) (int, Frame, error) {
startLen := len(data)
p.r.Reset(data)
frame, err := p.parseNext(p.r, encLevel)
n := startLen - p.r.Len()
p.r.Reset(nil)
return n, frame, err
}
func (p *frameParser) parseNext(r *bytes.Reader, encLevel protocol.EncryptionLevel) (Frame, error) {
for r.Len() != 0 {
typeByte, _ := p.r.ReadByte()
if typeByte == 0x0 { // PADDING frame
continue
}
r.UnreadByte()
f, err := p.parseFrame(r, typeByte, encLevel)
if err != nil {
return nil, &qerr.TransportError{
FrameType: uint64(typeByte),
ErrorCode: qerr.FrameEncodingError,
ErrorMessage: err.Error(),
}
}
return f, nil
}
return nil, nil
}
func (p *frameParser) parseFrame(r *bytes.Reader, typeByte byte, encLevel protocol.EncryptionLevel) (Frame, error) {
var frame Frame
var err error
if typeByte&0xf8 == 0x8 {
frame, err = parseStreamFrame(r, p.version)
} else {
switch typeByte {
case 0x1:
frame, err = parsePingFrame(r, p.version)
case 0x2, 0x3:
ackDelayExponent := p.ackDelayExponent
if encLevel != protocol.Encryption1RTT {
ackDelayExponent = protocol.DefaultAckDelayExponent
}
frame, err = parseAckFrame(r, ackDelayExponent, p.version)
case 0x4:
frame, err = parseResetStreamFrame(r, p.version)
case 0x5:
frame, err = parseStopSendingFrame(r, p.version)
case 0x6:
frame, err = parseCryptoFrame(r, p.version)
case 0x7:
frame, err = parseNewTokenFrame(r, p.version)
case 0x10:
frame, err = parseMaxDataFrame(r, p.version)
case 0x11:
frame, err = parseMaxStreamDataFrame(r, p.version)
case 0x12, 0x13:
frame, err = parseMaxStreamsFrame(r, p.version)
case 0x14:
frame, err = parseDataBlockedFrame(r, p.version)
case 0x15:
frame, err = parseStreamDataBlockedFrame(r, p.version)
case 0x16, 0x17:
frame, err = parseStreamsBlockedFrame(r, p.version)
case 0x18:
frame, err = parseNewConnectionIDFrame(r, p.version)
case 0x19:
frame, err = parseRetireConnectionIDFrame(r, p.version)
case 0x1a:
frame, err = parsePathChallengeFrame(r, p.version)
case 0x1b:
frame, err = parsePathResponseFrame(r, p.version)
case 0x1c, 0x1d:
frame, err = parseConnectionCloseFrame(r, p.version)
case 0x1e:
frame, err = parseHandshakeDoneFrame(r, p.version)
case 0x30, 0x31:
if p.supportsDatagrams {
frame, err = parseDatagramFrame(r, p.version)
break
}
fallthrough
default:
err = errors.New("unknown frame type")
}
}
if err != nil {
return nil, err
}
if !p.isAllowedAtEncLevel(frame, encLevel) {
return nil, fmt.Errorf("%s not allowed at encryption level %s", reflect.TypeOf(frame).Elem().Name(), encLevel)
}
return frame, nil
}
func (p *frameParser) isAllowedAtEncLevel(f Frame, encLevel protocol.EncryptionLevel) bool {
switch encLevel {
case protocol.EncryptionInitial, protocol.EncryptionHandshake:
switch f.(type) {
case *CryptoFrame, *AckFrame, *ConnectionCloseFrame, *PingFrame:
return true
default:
return false
}
case protocol.Encryption0RTT:
switch f.(type) {
case *CryptoFrame, *AckFrame, *ConnectionCloseFrame, *NewTokenFrame, *PathResponseFrame, *RetireConnectionIDFrame:
return false
default:
return true
}
case protocol.Encryption1RTT:
return true
default:
panic("unknown encryption level")
}
}
func (p *frameParser) SetAckDelayExponent(exp uint8) {
p.ackDelayExponent = exp
}