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wire: optimize generation of Version Negotiation packets (#4278)

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* wire: optimize generation of Version Negotiation packets

* protocol: optimize adding greased version numbers
This commit is contained in:
Marten Seemann
2024-02-01 14:54:04 +07:00
committed by GitHub
parent fbaa941ea1
commit 0582e931a5
3 changed files with 39 additions and 22 deletions
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23
internal/wire/version_negotiation.go
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@@ -1,13 +1,11 @@
package wire
import (
"bytes"
"crypto/rand"
"encoding/binary"
"errors"
"github.com/quic-go/quic-go/internal/protocol"
"github.com/quic-go/quic-go/internal/utils"
)
// ParseVersionNegotiationPacket parses a Version Negotiation packet.
@@ -37,20 +35,19 @@ func ParseVersionNegotiationPacket(b []byte) (dest, src protocol.ArbitraryLenCon
func ComposeVersionNegotiation(destConnID, srcConnID protocol.ArbitraryLenConnectionID, versions []protocol.Version) []byte {
greasedVersions := protocol.GetGreasedVersions(versions)
expectedLen := 1 /* type byte */ + 4 /* version field */ + 1 /* dest connection ID length field */ + destConnID.Len() + 1 /* src connection ID length field */ + 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 := make([]byte, 1+4 /* type byte and version field */, expectedLen)
_, _ = rand.Read(buf[:1]) // ignore the error here. It is not critical to have perfect random here.
// Setting the "QUIC bit" (0x40) is not required by the RFC,
// but it allows clients to demultiplex QUIC with a long list of other protocols.
// See RFC 9443 and https://mailarchive.ietf.org/arch/msg/quic/oR4kxGKY6mjtPC1CZegY1ED4beg/ for details.
buf.WriteByte(r[0] | 0xc0)
utils.BigEndian.WriteUint32(buf, 0) // version 0
buf.WriteByte(uint8(destConnID.Len()))
buf.Write(destConnID.Bytes())
buf.WriteByte(uint8(srcConnID.Len()))
buf.Write(srcConnID.Bytes())
buf[0] |= 0xc0
// The next 4 bytes are left at 0 (version number).
buf = append(buf, uint8(destConnID.Len()))
buf = append(buf, destConnID.Bytes()...)
buf = append(buf, uint8(srcConnID.Len()))
buf = append(buf, srcConnID.Bytes()...)
for _, v := range greasedVersions {
utils.BigEndian.WriteUint32(buf, uint32(v))
buf = binary.BigEndian.AppendUint32(buf, uint32(v))
}
return buf.Bytes()
return buf
}