forked from cerc-io/ipld-eth-server
103 lines
2.9 KiB
Go
103 lines
2.9 KiB
Go
package quic
|
|
|
|
import (
|
|
"bytes"
|
|
"fmt"
|
|
|
|
"github.com/lucas-clemente/quic-go/internal/handshake"
|
|
"github.com/lucas-clemente/quic-go/internal/protocol"
|
|
"github.com/lucas-clemente/quic-go/internal/utils"
|
|
"github.com/lucas-clemente/quic-go/internal/wire"
|
|
)
|
|
|
|
type unpackedPacket struct {
|
|
packetNumber protocol.PacketNumber // the decoded packet number
|
|
hdr *wire.ExtendedHeader
|
|
encryptionLevel protocol.EncryptionLevel
|
|
data []byte
|
|
}
|
|
|
|
// The packetUnpacker unpacks QUIC packets.
|
|
type packetUnpacker struct {
|
|
cs handshake.CryptoSetup
|
|
|
|
largestRcvdPacketNumber protocol.PacketNumber
|
|
|
|
version protocol.VersionNumber
|
|
}
|
|
|
|
var _ unpacker = &packetUnpacker{}
|
|
|
|
func newPacketUnpacker(cs handshake.CryptoSetup, version protocol.VersionNumber) unpacker {
|
|
return &packetUnpacker{
|
|
cs: cs,
|
|
version: version,
|
|
}
|
|
}
|
|
|
|
func (u *packetUnpacker) Unpack(hdr *wire.Header, data []byte) (*unpackedPacket, error) {
|
|
r := bytes.NewReader(data)
|
|
|
|
var encLevel protocol.EncryptionLevel
|
|
switch hdr.Type {
|
|
case protocol.PacketTypeInitial:
|
|
encLevel = protocol.EncryptionInitial
|
|
case protocol.PacketTypeHandshake:
|
|
encLevel = protocol.EncryptionHandshake
|
|
default:
|
|
if hdr.IsLongHeader {
|
|
return nil, fmt.Errorf("unknown packet type: %s", hdr.Type)
|
|
}
|
|
encLevel = protocol.Encryption1RTT
|
|
}
|
|
opener, err := u.cs.GetOpener(encLevel)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
hdrLen := int(hdr.ParsedLen())
|
|
if len(data) < hdrLen+4+16 {
|
|
return nil, fmt.Errorf("Packet too small. Expected at least 20 bytes after the header, got %d", len(data)-hdrLen)
|
|
}
|
|
// The packet number can be up to 4 bytes long, but we won't know the length until we decrypt it.
|
|
// 1. save a copy of the 4 bytes
|
|
origPNBytes := make([]byte, 4)
|
|
copy(origPNBytes, data[hdrLen:hdrLen+4])
|
|
// 2. decrypt the header, assuming a 4 byte packet number
|
|
opener.DecryptHeader(
|
|
data[hdrLen+4:hdrLen+4+16],
|
|
&data[0],
|
|
data[hdrLen:hdrLen+4],
|
|
)
|
|
// 3. parse the header (and learn the actual length of the packet number)
|
|
extHdr, err := hdr.ParseExtended(r, u.version)
|
|
if err != nil {
|
|
return nil, fmt.Errorf("error parsing extended header: %s", err)
|
|
}
|
|
extHdrLen := hdrLen + int(extHdr.PacketNumberLen)
|
|
// 4. if the packet number is shorter than 4 bytes, replace the remaining bytes with the copy we saved earlier
|
|
if extHdr.PacketNumberLen != protocol.PacketNumberLen4 {
|
|
copy(data[extHdrLen:hdrLen+4], origPNBytes[int(extHdr.PacketNumberLen):])
|
|
}
|
|
|
|
pn := protocol.DecodePacketNumber(
|
|
extHdr.PacketNumberLen,
|
|
u.largestRcvdPacketNumber,
|
|
extHdr.PacketNumber,
|
|
)
|
|
|
|
decrypted, err := opener.Open(data[extHdrLen:extHdrLen], data[extHdrLen:], pn, data[:extHdrLen])
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
// Only do this after decrypting, so we are sure the packet is not attacker-controlled
|
|
u.largestRcvdPacketNumber = utils.MaxPacketNumber(u.largestRcvdPacketNumber, pn)
|
|
|
|
return &unpackedPacket{
|
|
hdr: extHdr,
|
|
packetNumber: pn,
|
|
encryptionLevel: encLevel,
|
|
data: decrypted,
|
|
}, nil
|
|
}
|