1
0
mirror of https://github.com/v2fly/v2ray-core.git synced 2024-12-23 02:26:49 -05:00
v2fly/vendor/github.com/lucas-clemente/quic-go/internal/wire/version_negotiation.go
2018-11-21 10:49:41 +01:00

43 lines
1.5 KiB
Go

package wire
import (
"bytes"
"crypto/rand"
"github.com/lucas-clemente/quic-go/internal/protocol"
"github.com/lucas-clemente/quic-go/internal/utils"
)
// ComposeGQUICVersionNegotiation composes a Version Negotiation Packet for gQUIC
func ComposeGQUICVersionNegotiation(connID protocol.ConnectionID, versions []protocol.VersionNumber) []byte {
buf := bytes.NewBuffer(make([]byte, 0, 1+8+len(versions)*4))
buf.Write([]byte{0x1 | 0x8}) // type byte
buf.Write(connID)
for _, v := range versions {
utils.BigEndian.WriteUint32(buf, uint32(v))
}
return buf.Bytes()
}
// ComposeVersionNegotiation composes a Version Negotiation according to the IETF draft
func ComposeVersionNegotiation(destConnID, srcConnID protocol.ConnectionID, versions []protocol.VersionNumber) ([]byte, error) {
greasedVersions := protocol.GetGreasedVersions(versions)
expectedLen := 1 /* type byte */ + 4 /* version field */ + 1 /* connection ID length field */ + destConnID.Len() + srcConnID.Len() + len(greasedVersions)*4
buf := bytes.NewBuffer(make([]byte, 0, expectedLen))
r := make([]byte, 1)
_, _ = rand.Read(r) // ignore the error here. It is not critical to have perfect random here.
buf.WriteByte(r[0] | 0x80)
utils.BigEndian.WriteUint32(buf, 0) // version 0
connIDLen, err := encodeConnIDLen(destConnID, srcConnID)
if err != nil {
return nil, err
}
buf.WriteByte(connIDLen)
buf.Write(destConnID)
buf.Write(srcConnID)
for _, v := range greasedVersions {
utils.BigEndian.WriteUint32(buf, uint32(v))
}
return buf.Bytes(), nil
}