feat(backend): 提交后端审计修复与配套测试改动

backend/internal/service/upstream_response_limit_test.go

@@ -0,0 +1,37 @@
+package service
+
+import (
+	"bytes"
+	"errors"
+	"testing"
+
+	"github.com/Wei-Shaw/sub2api/internal/config"
+	"github.com/stretchr/testify/require"
+)
+
+func TestResolveUpstreamResponseReadLimit(t *testing.T) {
+	t.Run("use default when config missing", func(t *testing.T) {
+		require.Equal(t, defaultUpstreamResponseReadMaxBytes, resolveUpstreamResponseReadLimit(nil))
+	})
+
+	t.Run("use configured value", func(t *testing.T) {
+		cfg := &config.Config{}
+		cfg.Gateway.UpstreamResponseReadMaxBytes = 1234
+		require.Equal(t, int64(1234), resolveUpstreamResponseReadLimit(cfg))
+	})
+}
+
+func TestReadUpstreamResponseBodyLimited(t *testing.T) {
+	t.Run("within limit", func(t *testing.T) {
+		body, err := readUpstreamResponseBodyLimited(bytes.NewReader([]byte("ok")), 2)
+		require.NoError(t, err)
+		require.Equal(t, []byte("ok"), body)
+	})
+
+	t.Run("exceeds limit", func(t *testing.T) {
+		body, err := readUpstreamResponseBodyLimited(bytes.NewReader([]byte("toolong")), 3)
+		require.Nil(t, body)
+		require.Error(t, err)
+		require.True(t, errors.Is(err, ErrUpstreamResponseBodyTooLarge))
+	})
+}