feat: use last segment cid as root

- this also allows to return the PathMetadata, which also allows to set the correct X-Ipfs-Root header.
ipfs · Jun 8, 2023 · 7be4474 · 7be4474
1 parent ffcdaa1
commit 7be4474
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Showing 6 changed files with 19 additions and 24 deletions.
diff --git a/gateway/blocks_backend.go b/gateway/blocks_backend.go
@@ -232,20 +232,20 @@ func (bb *BlocksBackend) Head(ctx context.Context, path ImmutablePath) (ContentP
 	return md, fileNode, nil
 }
 
-func (bb *BlocksBackend) GetCAR(ctx context.Context, p ImmutablePath, params CarParams) (io.ReadCloser, error) {
+func (bb *BlocksBackend) GetCAR(ctx context.Context, p ImmutablePath, params CarParams) (ContentPathMetadata, io.ReadCloser, error) {
+	pathMetadata, err := bb.ResolvePath(ctx, p)
+	if err != nil {
+		return ContentPathMetadata{}, nil, err
+	}
+
 	contentPathStr := p.String()
 	if !strings.HasPrefix(contentPathStr, "/ipfs/") {
-		return nil, fmt.Errorf("path does not have /ipfs/ prefix")
-	}
-	firstSegment, _, _ := strings.Cut(contentPathStr[6:], "/")
-	rootCid, err := cid.Decode(firstSegment)
-	if err != nil {
-		return nil, err
+		return ContentPathMetadata{}, nil, fmt.Errorf("path does not have /ipfs/ prefix")
 	}
 
 	r, w := io.Pipe()
 	go func() {
-		cw, err := storage.NewWritable(w, []cid.Cid{rootCid}, car.WriteAsCarV1(true))
+		cw, err := storage.NewWritable(w, []cid.Cid{pathMetadata.LastSegment.Cid()}, car.WriteAsCarV1(true))
 		if err != nil {
 			// io.PipeWriter.CloseWithError always returns nil.
 			_ = w.CloseWithError(err)
@@ -275,7 +275,7 @@ func (bb *BlocksBackend) GetCAR(ctx context.Context, p ImmutablePath, params Car
 		_ = w.CloseWithError(carWriteErr)
 	}()
 
-	return r, nil
+	return pathMetadata, r, nil
 }
 
 // walkGatewaySimpleSelector walks the subgraph described by the path and terminal element parameters

diff --git a/gateway/gateway.go b/gateway/gateway.go
@@ -279,7 +279,7 @@ type IPFSBackend interface {
 
 	// GetCAR returns a CAR file for the given immutable path. It returns an error
 	// if there was an issue before the CAR streaming begins.
-	GetCAR(context.Context, ImmutablePath, CarParams) (io.ReadCloser, error)
+	GetCAR(context.Context, ImmutablePath, CarParams) (ContentPathMetadata, io.ReadCloser, error)
 
 	// IsCached returns whether or not the path exists locally.
 	IsCached(context.Context, path.Path) bool

diff --git a/gateway/gateway_test.go b/gateway/gateway_test.go
@@ -124,7 +124,7 @@ func (mb *mockBackend) Head(ctx context.Context, immutablePath ImmutablePath) (C
 	return mb.gw.Head(ctx, immutablePath)
 }
 
-func (mb *mockBackend) GetCAR(ctx context.Context, immutablePath ImmutablePath, params CarParams) (io.ReadCloser, error) {
+func (mb *mockBackend) GetCAR(ctx context.Context, immutablePath ImmutablePath, params CarParams) (ContentPathMetadata, io.ReadCloser, error) {
 	return mb.gw.GetCAR(ctx, immutablePath, params)
 }
 

diff --git a/gateway/handler_car.go b/gateway/handler_car.go
@@ -52,10 +52,6 @@ func (i *handler) serveCAR(ctx context.Context, w http.ResponseWriter, r *http.R
 		return false
 	}
 
-	// TODO(hacdias): this is incorrect and should have the full list of CIDs.
-	// https://github.com/ipfs/boxo/issues/221
-	w.Header().Set("X-Ipfs-Roots", rootCid.String())
-
 	// Set Content-Disposition
 	var name string
 	if urlFilename := r.URL.Query().Get("filename"); urlFilename != "" {
@@ -83,11 +79,12 @@ func (i *handler) serveCAR(ctx context.Context, w http.ResponseWriter, r *http.R
 		return false
 	}
 
-	carFile, err := i.backend.GetCAR(ctx, imPath, params)
+	md, carFile, err := i.backend.GetCAR(ctx, imPath, params)
 	if !i.handleRequestErrors(w, r, contentPath, err) {
 		return false
 	}
 	defer carFile.Close()
+	setIpfsRootsHeader(w, md)
 
 	// Make it clear we don't support range-requests over a car stream
 	// Partial downloads and resumes should be handled using requests for

diff --git a/gateway/handler_test.go b/gateway/handler_test.go
@@ -61,8 +61,8 @@ func (mb *errorMockBackend) Head(ctx context.Context, path ImmutablePath) (Conte
 	return ContentPathMetadata{}, nil, mb.err
 }
 
-func (mb *errorMockBackend) GetCAR(ctx context.Context, path ImmutablePath, params CarParams) (io.ReadCloser, error) {
-	return nil, mb.err
+func (mb *errorMockBackend) GetCAR(ctx context.Context, path ImmutablePath, params CarParams) (ContentPathMetadata, io.ReadCloser, error) {
+	return ContentPathMetadata{}, nil, mb.err
 }
 
 func (mb *errorMockBackend) ResolveMutable(ctx context.Context, path ipath.Path) (ImmutablePath, error) {
@@ -173,7 +173,7 @@ func (mb *panicMockBackend) Head(ctx context.Context, immutablePath ImmutablePat
 	panic("i am panicking")
 }
 
-func (mb *panicMockBackend) GetCAR(ctx context.Context, immutablePath ImmutablePath, params CarParams) (io.ReadCloser, error) {
+func (mb *panicMockBackend) GetCAR(ctx context.Context, immutablePath ImmutablePath, params CarParams) (ContentPathMetadata, io.ReadCloser, error) {
 	panic("i am panicking")
 }
 

diff --git a/gateway/metrics.go b/gateway/metrics.go
@@ -120,17 +120,15 @@ func (b *ipfsBackendWithMetrics) ResolvePath(ctx context.Context, path Immutable
 	return md, err
 }
 
-func (b *ipfsBackendWithMetrics) GetCAR(ctx context.Context, path ImmutablePath, params CarParams) (io.ReadCloser, error) {
+func (b *ipfsBackendWithMetrics) GetCAR(ctx context.Context, path ImmutablePath, params CarParams) (ContentPathMetadata, io.ReadCloser, error) {
 	begin := time.Now()
 	name := "IPFSBackend.GetCAR"
 	ctx, span := spanTrace(ctx, name, trace.WithAttributes(attribute.String("path", path.String())))
 	defer span.End()
 
-	rc, err := b.backend.GetCAR(ctx, path, params)
-
-	// TODO: handle errCh
+	md, rc, err := b.backend.GetCAR(ctx, path, params)
 	b.updateBackendCallMetric(name, err, begin)
-	return rc, err
+	return md, rc, err
 }
 
 func (b *ipfsBackendWithMetrics) IsCached(ctx context.Context, path path.Path) bool {