103 lines
2.7 KiB
Go
103 lines
2.7 KiB
Go
package wire
|
|
|
|
import (
|
|
"bytes"
|
|
"io"
|
|
|
|
"github.com/lucas-clemente/quic-go/internal/protocol"
|
|
"github.com/lucas-clemente/quic-go/quicvarint"
|
|
)
|
|
|
|
// 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 := quicvarint.Read(r)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
frame.Offset = protocol.ByteCount(offset)
|
|
dataLen, err := quicvarint.Read(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)
|
|
quicvarint.Write(b, uint64(f.Offset))
|
|
quicvarint.Write(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 + quicvarint.Len(uint64(f.Offset)) + quicvarint.Len(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 + quicvarint.Len(uint64(f.Offset)) + 1
|
|
if headerLen > maxSize {
|
|
return 0
|
|
}
|
|
maxDataLen := maxSize - headerLen
|
|
if quicvarint.Len(uint64(maxDataLen)) != 1 {
|
|
maxDataLen--
|
|
}
|
|
return maxDataLen
|
|
}
|
|
|
|
// MaybeSplitOffFrame splits a frame such that it is not bigger than n bytes.
|
|
// It returns if the frame was actually split.
|
|
// The frame might not be split if:
|
|
// * the size is large enough to fit the whole frame
|
|
// * the size is too small to fit even a 1-byte frame. In that case, the frame returned is nil.
|
|
func (f *CryptoFrame) MaybeSplitOffFrame(maxSize protocol.ByteCount, version protocol.VersionNumber) (*CryptoFrame, bool /* was splitting required */) {
|
|
if f.Length(version) <= maxSize {
|
|
return nil, false
|
|
}
|
|
|
|
n := f.MaxDataLen(maxSize)
|
|
if n == 0 {
|
|
return nil, true
|
|
}
|
|
|
|
newLen := protocol.ByteCount(len(f.Data)) - n
|
|
|
|
new := &CryptoFrame{}
|
|
new.Offset = f.Offset
|
|
new.Data = make([]byte, newLen)
|
|
|
|
// swap the data slices
|
|
new.Data, f.Data = f.Data, new.Data
|
|
|
|
copy(f.Data, new.Data[n:])
|
|
new.Data = new.Data[:n]
|
|
f.Offset += n
|
|
|
|
return new, true
|
|
}
|