append to a byte slice instead of a bytes.Buffer when serializing frames

fuzzing/frames/fuzz.go

@@ -55,10 +55,10 @@ func Fuzz(data []byte) int {
 		return 0
 	}
 
-	b := &bytes.Buffer{}
+	var b []byte
 	for _, f := range frames {
 		if f == nil { // PADDING frame
-			b.WriteByte(0x0)
+			b = append(b, 0)
 			continue
 		}
 		// We accept empty STREAM frames, but we don't write them.
@@ -68,11 +68,12 @@ func Fuzz(data []byte) int {
 				continue
 			}
 		}
-		lenBefore := b.Len()
-		if err := f.Write(b, version); err != nil {
+		lenBefore := len(b)
+		b, err := f.Write(b, version)
+		if err != nil {
 			panic(fmt.Sprintf("Error writing frame %#v: %s", f, err))
 		}
-		frameLen := b.Len() - lenBefore
+		frameLen := len(b) - lenBefore
 		if f.Length(version) != protocol.ByteCount(frameLen) {
 			panic(fmt.Sprintf("Inconsistent frame length for %#v: expected %d, got %d", f, frameLen, f.Length(version)))
 		}
@@ -80,8 +81,8 @@ func Fuzz(data []byte) int {
 			sf.PutBack()
 		}
 	}
-	if b.Len() > parsedLen {
-		panic(fmt.Sprintf("Serialized length (%d) is longer than parsed length (%d)", b.Len(), parsedLen))
+	if len(b) > parsedLen {
+		panic(fmt.Sprintf("Serialized length (%d) is longer than parsed length (%d)", len(b), parsedLen))
 	}
 	return 1
 }