route/vendor/github.com/lucas-clemente/quic-go/internal/wire/version_negotiation.go

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2018-01-03 19:19:49 +00:00
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 {
fullReply := &bytes.Buffer{}
ph := Header{
ConnectionID: connID,
PacketNumber: 1,
VersionFlag: true,
IsVersionNegotiation: true,
}
if err := ph.writePublicHeader(fullReply, protocol.PerspectiveServer, protocol.VersionWhatever); err != nil {
utils.Errorf("error composing version negotiation packet: %s", err.Error())
return nil
}
writeVersions(fullReply, versions)
return fullReply.Bytes()
}
// ComposeVersionNegotiation composes a Version Negotiation according to the IETF draft
func ComposeVersionNegotiation(
connID protocol.ConnectionID,
pn protocol.PacketNumber,
versions []protocol.VersionNumber,
) []byte {
fullReply := &bytes.Buffer{}
r := make([]byte, 1)
_, _ = rand.Read(r) // ignore the error here. It is not critical to have perfect random here.
h := Header{
IsLongHeader: true,
Type: protocol.PacketType(r[0] | 0x80),
ConnectionID: connID,
PacketNumber: pn,
Version: 0,
IsVersionNegotiation: true,
}
if err := h.writeHeader(fullReply); err != nil {
utils.Errorf("error composing version negotiation packet: %s", err.Error())
return nil
}
writeVersions(fullReply, versions)
return fullReply.Bytes()
}
// writeVersions writes the versions for a Version Negotiation Packet.
// It inserts one reserved version number at a random position.
func writeVersions(buf *bytes.Buffer, supported []protocol.VersionNumber) {
for _, v := range protocol.GetGreasedVersions(supported) {
utils.BigEndian.WriteUint32(buf, uint32(v))
}
}