62 lines
1.5 KiB
Go
62 lines
1.5 KiB
Go
package recordlayer
|
|
|
|
import (
|
|
"encoding/binary"
|
|
|
|
"github.com/pion/dtls/v2/internal/util"
|
|
"github.com/pion/dtls/v2/pkg/protocol"
|
|
)
|
|
|
|
// Header implements a TLS RecordLayer header
|
|
type Header struct {
|
|
ContentType protocol.ContentType
|
|
ContentLen uint16
|
|
Version protocol.Version
|
|
Epoch uint16
|
|
SequenceNumber uint64 // uint48 in spec
|
|
}
|
|
|
|
// RecordLayer enums
|
|
const (
|
|
HeaderSize = 13
|
|
MaxSequenceNumber = 0x0000FFFFFFFFFFFF
|
|
)
|
|
|
|
// Marshal encodes a TLS RecordLayer Header to binary
|
|
func (h *Header) Marshal() ([]byte, error) {
|
|
if h.SequenceNumber > MaxSequenceNumber {
|
|
return nil, errSequenceNumberOverflow
|
|
}
|
|
|
|
out := make([]byte, HeaderSize)
|
|
out[0] = byte(h.ContentType)
|
|
out[1] = h.Version.Major
|
|
out[2] = h.Version.Minor
|
|
binary.BigEndian.PutUint16(out[3:], h.Epoch)
|
|
util.PutBigEndianUint48(out[5:], h.SequenceNumber)
|
|
binary.BigEndian.PutUint16(out[HeaderSize-2:], h.ContentLen)
|
|
return out, nil
|
|
}
|
|
|
|
// Unmarshal populates a TLS RecordLayer Header from binary
|
|
func (h *Header) Unmarshal(data []byte) error {
|
|
if len(data) < HeaderSize {
|
|
return errBufferTooSmall
|
|
}
|
|
h.ContentType = protocol.ContentType(data[0])
|
|
h.Version.Major = data[1]
|
|
h.Version.Minor = data[2]
|
|
h.Epoch = binary.BigEndian.Uint16(data[3:])
|
|
|
|
// SequenceNumber is stored as uint48, make into uint64
|
|
seqCopy := make([]byte, 8)
|
|
copy(seqCopy[2:], data[5:11])
|
|
h.SequenceNumber = binary.BigEndian.Uint64(seqCopy)
|
|
|
|
if !h.Version.Equal(protocol.Version1_0) && !h.Version.Equal(protocol.Version1_2) {
|
|
return errUnsupportedProtocolVersion
|
|
}
|
|
|
|
return nil
|
|
}
|