limit: clamp bandwidth limiter burst (#5471)

pkg/util/limit/limiter_test.go

@@ -0,0 +1,65 @@
+// Copyright 2026 The frp Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package limit
+
+import (
+	"bytes"
+	"strconv"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	"golang.org/x/time/rate"
+)
+
+func TestNewBandwidthLimiterClampsBurstToTargetInt(t *testing.T) {
+	const bytesPerSecond = int64(1 << 31)
+
+	limiter := NewBandwidthLimiter(bytesPerSecond)
+	require.NotNil(t, limiter)
+
+	wantBurst := bytesPerSecond
+	maxInt := int64(^uint(0) >> 1)
+	if wantBurst > maxInt {
+		wantBurst = maxInt
+	}
+	require.Equal(t, int(wantBurst), limiter.Burst())
+	require.Equal(t, rate.Limit(float64(bytesPerSecond)), limiter.Limit())
+}
+
+func TestNewBandwidthLimiterDisablesNonPositiveLimit(t *testing.T) {
+	require.Nil(t, NewBandwidthLimiter(0))
+	require.Nil(t, NewBandwidthLimiter(-1))
+}
+
+func TestReaderAndWriterRejectInvalidBurst(t *testing.T) {
+	for _, burst := range []int{0, -1} {
+		t.Run("reader/"+strconv.Itoa(burst), func(t *testing.T) {
+			reader := NewReader(strings.NewReader("payload"), rate.NewLimiter(rate.Limit(1), burst))
+			n, err := reader.Read(make([]byte, 1))
+			require.Zero(t, n)
+			require.EqualError(t, err, "invalid limiter burst: "+strconv.Itoa(burst))
+		})
+
+		t.Run("writer/"+strconv.Itoa(burst), func(t *testing.T) {
+			var dst bytes.Buffer
+			writer := NewWriter(&dst, rate.NewLimiter(rate.Limit(1), burst))
+			n, err := writer.Write([]byte("payload"))
+			require.Zero(t, n)
+			require.EqualError(t, err, "invalid limiter burst: "+strconv.Itoa(burst))
+			require.Empty(t, dst.Bytes())
+		})
+	}
+}