fix(gateway): fix codec range requests

gateway/blocks_backend.go

@@ -162,8 +162,10 @@ func (bb *BlocksBackend) Get(ctx context.Context, path ImmutablePath, ranges ...
 	}
 
 	rootCodec := nd.Cid().Prefix().GetCodec()
+
 	// This covers both Raw blocks and terminal IPLD codecs like dag-cbor and dag-json
 	// Note: while only cbor, json, dag-cbor, and dag-json are currently supported by gateways this could change
+	// Note: For the raw codec we return just the relevant range rather than the entire block
 	if rootCodec != uint64(mc.DagPb) {
 		f := files.NewBytesFile(nd.RawData())
 
@@ -172,8 +174,10 @@ func (bb *BlocksBackend) Get(ctx context.Context, path ImmutablePath, ranges ...
 			return ContentPathMetadata{}, nil, err
 		}
 
-		if err := seekToRangeStart(f, ra); err != nil {
-			return ContentPathMetadata{}, nil, err
+		if rootCodec == uint64(mc.Raw) {
+			if err := seekToRangeStart(f, ra); err != nil {
+				return ContentPathMetadata{}, nil, err
+			}
 		}
 
 		return md, NewGetResponseFromReader(f, fileSize), nil

gateway/gateway.go

@@ -358,6 +358,9 @@ type IPFSBackend interface {
 	//     file will still need magic bytes from the very beginning for content
 	//     type sniffing).
 	//   - A range request for a directory currently holds no semantic meaning.
+	//   - For non-UnixFS (and non-raw data) such as terminal IPLD dag-cbor/json, etc. blocks the returned response
+	//     bytes should be the complete block and returned as an [io.ReadSeekCloser] starting at the beginning of the
+	//     block rather than as an [io.ReadCloser] that starts at the beginning of the range request.
 	//
 	// [HTTP Byte Ranges]: https://httpwg.org/specs/rfc9110.html#rfc.section.14.1.2
 	Get(context.Context, ImmutablePath, ...ByteRange) (ContentPathMetadata, *GetResponse, error)

gateway/handler.go

@@ -92,7 +92,7 @@ func NewHandler(c Config, backend IPFSBackend) http.Handler {
 	return newHandlerWithMetrics(&c, backend)
 }
 
-// serveContent replies to the request using the content in the provided ReadSeeker
+// serveContent replies to the request using the content in the provided Reader
 // and returns the status code written and any error encountered during a write.
 // It wraps httpServeContent (a close clone of http.ServeContent) which takes care of If-None-Match+Etag,
 // Content-Length and range requests.

gateway/handler_codec.go

@@ -75,14 +75,10 @@ func (i *handler) serveCodec(ctx context.Context, w http.ResponseWriter, r *http
 		return false
 	}
 
-	if !i.seekToStartOfFirstRange(w, r, data) {
-		return false
-	}
-
 	return i.renderCodec(ctx, w, r, rq, blockSize, data)
 }
 
-func (i *handler) renderCodec(ctx context.Context, w http.ResponseWriter, r *http.Request, rq *requestData, blockSize int64, blockData io.ReadCloser) bool {
+func (i *handler) renderCodec(ctx context.Context, w http.ResponseWriter, r *http.Request, rq *requestData, blockSize int64, blockData io.ReadSeekCloser) bool {
 	resolvedPath := rq.pathMetadata.LastSegment
 	ctx, span := spanTrace(ctx, "Handler.RenderCodec", trace.WithAttributes(attribute.String("path", resolvedPath.String()), attribute.String("requestedContentType", rq.responseFormat)))
 	defer span.End()
@@ -239,9 +235,13 @@ func parseNode(blockCid cid.Cid, blockData io.Reader) *assets.ParsedNode {
 }
 
 // serveCodecRaw returns the raw block without any conversion
-func (i *handler) serveCodecRaw(ctx context.Context, w http.ResponseWriter, r *http.Request, blockSize int64, blockData io.ReadCloser, contentPath ipath.Path, modtime, begin time.Time) bool {
+func (i *handler) serveCodecRaw(ctx context.Context, w http.ResponseWriter, r *http.Request, blockSize int64, blockData io.ReadSeekCloser, contentPath ipath.Path, modtime, begin time.Time) bool {
 	// ServeContent will take care of
-	// If-None-Match+Etag, Content-Length and range requests
+	// If-None-Match+Etag, Content-Length and setting range request headers after we've already seeked to the start of
+	// the first range
+	if !i.seekToStartOfFirstRange(w, r, blockData) {
+		return false
+	}
 	_, dataSent, _ := serveContent(w, r, modtime, blockSize, blockData)
 
 	if dataSent {

gateway/handler_defaults.go

@@ -99,14 +99,19 @@ func (i *handler) serveDefaults(ctx context.Context, w http.ResponseWriter, r *h
 	case mc.Json, mc.DagJson, mc.Cbor, mc.DagCbor:
 		rq.logger.Debugw("serving codec", "path", rq.contentPath)
 		var blockSize int64
-		var dataToRender io.ReadCloser
+		var dataToRender io.ReadSeekCloser
 		if headResp != nil {
 			blockSize = headResp.bytesSize
 			dataToRender = nil
 		} else {
 			blockSize = getResp.bytesSize
-			dataToRender = getResp.bytes
+			dataAsReadSeekCloser, ok := getResp.bytes.(io.ReadSeekCloser)
+			if !ok {
+				i.webError(w, r, fmt.Errorf("expected returned non-UnixFS data to be seekable"), http.StatusInternalServerError)
+			}
+			dataToRender = dataAsReadSeekCloser
 		}
+
 		return i.renderCodec(r.Context(), w, r, rq, blockSize, dataToRender)
 	default:
 		rq.logger.Debugw("serving unixfs", "path", rq.contentPath)