fix(http): use Content-Range total size for 206 responses (#1545)

2026-11-04 08:10:55 +00:00 · 2026-09-23 09:52:59 +08:00
1 parent f0dab90e09
commit 363153fa33
@@ -417,12 +417,26 @@ func (f *Fetcher) Resolve(req *base.Request, opts *base.Options) error {
 		res.Range = true
 	}

-	// Get content length from Content-Length header
-	contentLength := resp.Header.Get(base.HttpHeaderContentLength)
-	if contentLength != "" {
-		parse, err := strconv.ParseInt(contentLength, 10, 64)
-		if err == nil {
-			res.Size = parse
+	// A partial response describes one segment, not the whole resource.
+	reuseResolveBody := true
+	if resp.StatusCode == base.HttpCodePartialContent {
+		start, _, total, err := parseRangeResponse(resp)
+		if err != nil {
+			resp.Body.Close()
+			f.setState(stateError)
+			return err
+		}
+		res.Size = total
+		res.Range = true
+		// Prefetch is a contiguous prefix copied at offset zero. A segment
+		// starting elsewhere must be fetched again through the Range path.
+		reuseResolveBody = start == 0
+	} else {
+		contentLength := resp.Header.Get(base.HttpHeaderContentLength)
+		if contentLength != "" {
+			if size, err := strconv.ParseInt(contentLength, 10, 64); err == nil {
+				res.Size = size
+			}
 		}
 	}

@@ -467,7 +481,12 @@ func (f *Fetcher) Resolve(req *base.Request, opts *base.Options) error {
 	// IMPORTANT: Keep the response body open for downloading in Start phase
 	// This is crucial for one-time URLs that can only be accessed once
 	f.resolveRespLock.Lock()
-	f.resolveResp = resp
+	if reuseResolveBody {
+		f.resolveResp = resp
+	} else {
+		resp.Body.Close()
+		f.prefetchDone.Store(true)
+	}
 	f.resolveRespLock.Unlock()

 	f.setState(stateResolved)
@@ -479,7 +498,7 @@ func (f *Fetcher) Resolve(req *base.Request, opts *base.Options) error {

 	// Start async prefetch in background (only for range-supported resources)
 	// For non-range resources, the response will be used directly in Start
-	if res.Range {
+	if res.Range && reuseResolveBody {
 		f.prefetchStopCh = make(chan struct{})
 		f.resolveFallback.Store(true)
 		go f.asyncPrefetch()
@@ -1544,27 +1563,41 @@ func (f *Fetcher) completeFromResolveFallback(conn *connection) bool {
 	return true
 }

-func validateRangeResponse(resp *http.Response, requestedStart int64, requestedEnd *int64, totalSize int64) (int64, int64, error) {
+// parseRangeResponse validates a single byte range with a known complete length.
+// Unknown totals are rejected: a segment length cannot stand in for resource size.
+func parseRangeResponse(resp *http.Response) (int64, int64, int64, error) {
 	contentRange := resp.Header.Get(base.HttpHeaderContentRange)
 	fields := strings.Fields(contentRange)
 	if len(fields) != 2 || !strings.EqualFold(fields[0], base.HttpHeaderBytes) {
-		return 0, 0, fmt.Errorf("%w: malformed Content-Range %q", errInvalidRangeResponse, contentRange)
+		return 0, 0, 0, fmt.Errorf("%w: malformed Content-Range %q", errInvalidRangeResponse, contentRange)
 	}

 	rangeAndTotal := strings.Split(fields[1], "/")
 	if len(rangeAndTotal) != 2 {
-		return 0, 0, fmt.Errorf("%w: malformed Content-Range %q", errInvalidRangeResponse, contentRange)
+		return 0, 0, 0, fmt.Errorf("%w: malformed Content-Range %q", errInvalidRangeResponse, contentRange)
 	}
 	bounds := strings.Split(rangeAndTotal[0], "-")
 	if len(bounds) != 2 {
-		return 0, 0, fmt.Errorf("%w: malformed Content-Range %q", errInvalidRangeResponse, contentRange)
+		return 0, 0, 0, fmt.Errorf("%w: malformed Content-Range %q", errInvalidRangeResponse, contentRange)
 	}

 	start, startErr := strconv.ParseInt(bounds[0], 10, 64)
 	end, endErr := strconv.ParseInt(bounds[1], 10, 64)
 	total, totalErr := strconv.ParseInt(rangeAndTotal[1], 10, 64)
 	if startErr != nil || endErr != nil || totalErr != nil || start < 0 || end < start || total <= end {
-		return 0, 0, fmt.Errorf("%w: malformed Content-Range %q", errInvalidRangeResponse, contentRange)
+		return 0, 0, 0, fmt.Errorf("%w: malformed Content-Range %q", errInvalidRangeResponse, contentRange)
+	}
+	expectedLength := end - start + 1
+	if resp.ContentLength >= 0 && resp.ContentLength != expectedLength {
+		return 0, 0, 0, fmt.Errorf("%w: Content-Length %d does not match range length %d", errInvalidRangeResponse, resp.ContentLength, expectedLength)
+	}
+	return start, end, total, nil
+}
+
+func validateRangeResponse(resp *http.Response, requestedStart int64, requestedEnd *int64, totalSize int64) (int64, int64, error) {
+	start, end, total, err := parseRangeResponse(resp)
+	if err != nil {
+		return 0, 0, err
 	}
 	if start != requestedStart || (requestedEnd != nil && end != *requestedEnd) || (requestedEnd == nil && end != total-1) {
 		return 0, 0, fmt.Errorf("%w: Content-Range %d-%d does not match requested range", errInvalidRangeResponse, start, end)
@@ -1573,11 +1606,7 @@ func validateRangeResponse(resp *http.Response, requestedStart int64, requestedE
 		return 0, 0, fmt.Errorf("%w: Content-Range total %d does not match resource size %d", errInvalidRangeResponse, total, totalSize)
 	}

-	expectedLength := end - start + 1
-	if resp.ContentLength >= 0 && resp.ContentLength != expectedLength {
-		return 0, 0, fmt.Errorf("%w: Content-Length %d does not match range length %d", errInvalidRangeResponse, resp.ContentLength, expectedLength)
-	}
-	return expectedLength, total, nil
+	return end - start + 1, total, nil
 }

 func (f *Fetcher) resolveOpenEndedRange(conn *connection, totalSize int64) error {
@@ -0,0 +1,119 @@
+package http
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"testing"
+
+	"github.com/GopeedLab/gopeed/pkg/base"
+	fhttp "github.com/GopeedLab/gopeed/pkg/protocol/http"
+)
+
+func TestResolveResponseSize(t *testing.T) {
+	for _, tc := range []struct {
+		name                 string
+		status               int
+		length, contentRange string
+		size                 int64
+		invalid              bool
+	}{
+		{"full", 200, "801571015", "", 801571015, false},
+		{"partial_prefix", 206, "472321339", "bytes 0-472321338/801571015", 801571015, false},
+		{"partial_nonzero", 206, "100000", "bytes 100000-199999/801571015", 801571015, false},
+		{"second_report", 206, "335134409", "bytes 0-335134408/552140234", 552140234, false},
+		{"length_mismatch", 206, "10", "bytes 0-19/100", 0, true},
+		{"unknown_total", 206, "472321339", "bytes 0-472321338/*", 0, true},
+		{"missing_range", 206, "10", "", 0, true},
+		{"malformed_range", 206, "10", "bytes invalid", 0, true},
+		{"invalid_bounds", 206, "10", "bytes 20-10/100", 0, true},
+		{"invalid_total", 206, "10", "bytes 0-9/9", 0, true},
+		{"overflow", 206, "10", "bytes 0-9/9223372036854775808", 0, true},
+		{"chunked_partial", 206, "", "bytes 0-9/100", 100, false},
+		{"unknown_full", 200, "", "", 0, false},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+				if tc.length != "" {
+					w.Header().Set("Content-Length", tc.length)
+				}
+				if tc.contentRange != "" {
+					w.Header().Set("Content-Range", tc.contentRange)
+				}
+				w.WriteHeader(tc.status)
+				w.(http.Flusher).Flush()
+			}))
+			defer server.Close()
+			f := buildFetcher()
+			defer f.Close()
+			err := f.Resolve(&base.Request{URL: server.URL + "/file"}, &base.Options{Path: t.TempDir()})
+			if tc.invalid {
+				if !errors.Is(err, errInvalidRangeResponse) {
+					t.Fatalf("Resolve error = %v, want invalid range", err)
+				}
+				if f.meta.Res != nil || f.resolveResp != nil || f.getState() != stateError {
+					t.Fatal("invalid response was retained or published")
+				}
+				return
+			}
+			if err != nil {
+				t.Fatal(err)
+			}
+			if f.meta.Res.Size != tc.size || f.meta.Res.Files[0].Size != tc.size {
+				t.Fatalf("resource/file size = %d/%d, want %d", f.meta.Res.Size, f.meta.Res.Files[0].Size, tc.size)
+			}
+			if tc.status == 206 && !f.meta.Res.Range {
+				t.Fatal("partial response must enable Range downloads")
+			}
+		})
+	}
+}
+
+func TestDownloadPartialResolve(t *testing.T) {
+	payload := make([]byte, 256*1024)
+	for i := range payload {
+		payload[i] = byte(i*31 + i/251)
+	}
+	for _, start := range []int{0, 100000} {
+		for _, connections := range []int{1, 4} {
+			t.Run(fmt.Sprintf("start_%d_connections_%d", start, connections), func(t *testing.T) {
+				server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+					begin, end := start, start+9999
+					if h := r.Header.Get("Range"); h != "" {
+						if _, err := fmt.Sscanf(h, "bytes=%d-%d", &begin, &end); err != nil {
+							t.Errorf("invalid request range %q: %v", h, err)
+							w.WriteHeader(400)
+							return
+						}
+					}
+					w.Header().Set("Content-Length", fmt.Sprint(end-begin+1))
+					w.Header().Set("Content-Range", fmt.Sprintf("bytes %d-%d/%d", begin, end, len(payload)))
+					w.WriteHeader(206)
+					w.Write(payload[begin : end+1])
+				}))
+				defer server.Close()
+				f := buildFetcher()
+				defer f.Close()
+				if err := f.Resolve(&base.Request{URL: server.URL + "/file"}, &base.Options{Path: t.TempDir(), Name: "file", Extra: &fhttp.OptsExtra{Connections: connections}}); err != nil {
+					t.Fatal(err)
+				}
+				if err := f.Start(); err != nil {
+					t.Fatal(err)
+				}
+				if err := f.Wait(); err != nil {
+					t.Fatal(err)
+				}
+				got, err := os.ReadFile(f.meta.SingleFilepath())
+				if err != nil {
+					t.Fatal(err)
+				}
+				if !bytes.Equal(got, payload) {
+					t.Fatalf("download content mismatch: got %d bytes, want %d", len(got), len(payload))
+				}
+			})
+		}
+	}
+}