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crypto_frame.go
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crypto_frame.go
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package wire
import (
"bytes"
"io"
"v2ray.com/core/external/github.com/lucas-clemente/quic-go/internal/protocol"
"v2ray.com/core/external/github.com/lucas-clemente/quic-go/internal/utils"
)
// A CryptoFrame is a CRYPTO frame
type CryptoFrame struct {
Offset protocol.ByteCount
Data []byte
}
func parseCryptoFrame(r *bytes.Reader, _ protocol.VersionNumber) (*CryptoFrame, error) {
if _, err := r.ReadByte(); err != nil {
return nil, err
}
frame := &CryptoFrame{}
offset, err := utils.ReadVarInt(r)
if err != nil {
return nil, err
}
frame.Offset = protocol.ByteCount(offset)
dataLen, err := utils.ReadVarInt(r)
if err != nil {
return nil, err
}
if dataLen > uint64(r.Len()) {
return nil, io.EOF
}
if dataLen != 0 {
frame.Data = make([]byte, dataLen)
if _, err := io.ReadFull(r, frame.Data); err != nil {
// this should never happen, since we already checked the dataLen earlier
return nil, err
}
}
return frame, nil
}
func (f *CryptoFrame) Write(b *bytes.Buffer, _ protocol.VersionNumber) error {
b.WriteByte(0x6)
utils.WriteVarInt(b, uint64(f.Offset))
utils.WriteVarInt(b, uint64(len(f.Data)))
b.Write(f.Data)
return nil
}
// Length of a written frame
func (f *CryptoFrame) Length(_ protocol.VersionNumber) protocol.ByteCount {
return 1 + utils.VarIntLen(uint64(f.Offset)) + utils.VarIntLen(uint64(len(f.Data))) + protocol.ByteCount(len(f.Data))
}
// MaxDataLen returns the maximum data length
func (f *CryptoFrame) MaxDataLen(maxSize protocol.ByteCount) protocol.ByteCount {
// pretend that the data size will be 1 bytes
// if it turns out that varint encoding the length will consume 2 bytes, we need to adjust the data length afterwards
headerLen := 1 + utils.VarIntLen(uint64(f.Offset)) + 1
if headerLen > maxSize {
return 0
}
maxDataLen := maxSize - headerLen
if utils.VarIntLen(uint64(maxDataLen)) != 1 {
maxDataLen--
}
return maxDataLen
}