grease transport parameters

internal/handshake/transport_parameters.go

@@ -6,6 +6,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"math/rand"
 	"sort"
 	"time"
 
@@ -13,6 +14,10 @@ import (
 	"github.com/lucas-clemente/quic-go/internal/utils"
 )
 
+func init() {
+	rand.Seed(time.Now().UTC().UnixNano())
+}
+
 type transportParameterID uint16
 
 const (
@@ -204,6 +209,14 @@ func (p *TransportParameters) Marshal() []byte {
 	b := &bytes.Buffer{}
 	b.Write([]byte{0, 0}) // length. Will be replaced later
 
+	// add a greased value
+	utils.BigEndian.WriteUint16(b, uint16(27+31*rand.Intn(100)))
+	len := rand.Intn(16)
+	randomData := make([]byte, len)
+	rand.Read(randomData)
+	utils.BigEndian.WriteUint16(b, uint16(len))
+	b.Write(randomData)
+
 	// initial_max_stream_data_bidi_local
 	p.marshalVarintParam(b, initialMaxStreamDataBidiLocalParameterID, uint64(p.InitialMaxStreamDataBidiLocal))
 	// initial_max_stream_data_bidi_remote