extend the error code space to 32 bits

errors.go

@@ -8,14 +8,14 @@ import (
 )
 
 // StreamErrorCode is an error code used for stream termination.
-type StreamErrorCode uint8
+type StreamErrorCode uint32
 
 // SessionErrorCode is an error code for session termination.
 type SessionErrorCode uint32
 
 const (
 	firstErrorCode = 0x52e4a40fa8db
-	lastErrorCode  = 0x52e4a40fa9e2
+	lastErrorCode  = 0x52e5ac983162
 )
 
 func webtransportCodeToHTTPCode(n StreamErrorCode) quic.StreamErrorCode {

errors_test.go

@@ -3,39 +3,57 @@ package webtransport
 import (
 	"errors"
 	"math"
+	"math/rand"
 	"testing"
+	"time"
 
 	"github.com/quic-go/quic-go"
 
 	"github.com/stretchr/testify/require"
 )
 
+var random = rand.New(rand.NewSource(time.Now().UnixNano()))
+
 func TestErrorCodeRoundTrip(t *testing.T) {
-	for i := 0; i < math.MaxUint8; i++ {
-		httpCode := webtransportCodeToHTTPCode(StreamErrorCode(i))
+	for i := 0; i < 1e4; i++ {
+		n := StreamErrorCode(random.Int63())
+		httpCode := webtransportCodeToHTTPCode(n)
 		errorCode, err := httpCodeToWebtransportCode(httpCode)
 		require.NoError(t, err)
-		require.Equal(t, StreamErrorCode(i), errorCode)
+		require.Equal(t, n, errorCode)
 	}
 }
 
 func TestErrorCodeConversionErrors(t *testing.T) {
 	t.Run("too small", func(t *testing.T) {
-		_, err := httpCodeToWebtransportCode(firstErrorCode - 1)
+		first, err := httpCodeToWebtransportCode(firstErrorCode)
+		require.NoError(t, err)
+		require.Zero(t, first)
+		_, err = httpCodeToWebtransportCode(firstErrorCode - 1)
 		require.EqualError(t, err, "error code outside of expected range")
 	})
 
 	t.Run("too large", func(t *testing.T) {
-		_, err := httpCodeToWebtransportCode(lastErrorCode + 1)
+		last, err := httpCodeToWebtransportCode(lastErrorCode)
+		require.NoError(t, err)
+		require.Equal(t, StreamErrorCode(math.MaxUint32), last)
+		_, err = httpCodeToWebtransportCode(lastErrorCode + 1)
 		require.EqualError(t, err, "error code outside of expected range")
 	})
 
 	t.Run("greased value", func(t *testing.T) {
-		invalids := []quic.StreamErrorCode{0x52e4a40fa8f9, 0x52e4a40fa918, 0x52e4a40fa937, 0x52e4a40fa956, 0x52e4a40fa975, 0x52e4a40fa994, 0x52e4a40fa9b3, 0x52e4a40fa9d2}
-		for _, c := range invalids {
-			_, err := httpCodeToWebtransportCode(c)
+		var counter int
+		for i := 0; i < 1e4; i++ {
+			c := firstErrorCode + uint64(uint32(random.Int63()))
+			if (c-0x21)%0x1f != 0 {
+				continue
+			}
+			counter++
+			_, err := httpCodeToWebtransportCode(quic.StreamErrorCode(c))
 			require.EqualError(t, err, "invalid error code")
 		}
+		t.Logf("checked %d greased values", counter)
+		require.NotZero(t, counter)
 	})
 }