make wire an internal package

internal/wire/version_negotiation.go

@@ -0,0 +1,26 @@
+package wire
+
+import (
+	"bytes"
+
+	"github.com/lucas-clemente/quic-go/internal/utils"
+	"github.com/lucas-clemente/quic-go/protocol"
+)
+
+// ComposeVersionNegotiation composes a Version Negotiation Packet
+func ComposeVersionNegotiation(connectionID protocol.ConnectionID, versions []protocol.VersionNumber) []byte {
+	fullReply := &bytes.Buffer{}
+	responsePublicHeader := PublicHeader{
+		ConnectionID: connectionID,
+		PacketNumber: 1,
+		VersionFlag:  true,
+	}
+	err := responsePublicHeader.Write(fullReply, protocol.VersionWhatever, protocol.PerspectiveServer)
+	if err != nil {
+		utils.Errorf("error composing version negotiation packet: %s", err.Error())
+	}
+	for _, v := range versions {
+		utils.LittleEndian.WriteUint32(fullReply, protocol.VersionNumberToTag(v))
+	}
+	return fullReply.Bytes()
+}