wip: add application/json and application/cbor

Author: hacdias

core/corehttp/gateway_handler.go

@@ -432,12 +432,14 @@ func (i *gatewayHandler) getOrHeadHandler(w http.ResponseWriter, r *http.Request
 		i.serveCAR(r.Context(), w, r, resolvedPath, contentPath, carVersion, begin)
 		return
 	case "application/vnd.ipld.dag-json":
+	case "application/json":
 		logger.Debugw("serving dag-json", "path", contentPath)
-		i.serveJSON(r.Context(), w, r, resolvedPath, begin, "application/vnd.ipld.dag-json", uint64(mc.DagJson))
+		i.serveCodec(r.Context(), w, r, resolvedPath, contentPath, begin, responseFormat, uint64(mc.DagJson))
 		return
 	case "application/vnd.ipld.dag-cbor":
+	case "application/cbor":
 		logger.Debugw("serving dag-cbor", "path", contentPath)
-		i.serveJSON(r.Context(), w, r, resolvedPath, begin, "application/vnd.ipld.dag-cbor", uint64(mc.DagCbor))
+		i.serveCodec(r.Context(), w, r, resolvedPath, contentPath, begin, responseFormat, uint64(mc.DagCbor))
 		return
 	default: // catch-all for unsuported application/vnd.*
 		err := fmt.Errorf("unsupported format %q", responseFormat)
@@ -870,16 +872,22 @@ func customResponseFormat(r *http.Request) (mediaType string, params map[string]
 			return "application/vnd.ipld.car", nil, nil
 		case "dag-json":
 			return "application/vnd.ipld.dag-json", nil, nil
+		case "json":
+			return "application/json", nil, nil
 		case "dag-cbor":
 			return "application/vnd.ipld.dag-cbor", nil, nil
+		case "cbor":
+			return "application/cbor", nil, nil
 		}
 	}
 	// Browsers and other user agents will send Accept header with generic types like:
 	// Accept:text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,*/*;q=0.8
 	// We only care about explciit, vendor-specific content-types.
 	for _, accept := range r.Header.Values("Accept") {
 		// respond to the very first ipld content type
-		if strings.HasPrefix(accept, "application/vnd.ipld") {
+		if strings.HasPrefix(accept, "application/vnd.ipld") ||
+			strings.HasPrefix(accept, "application/json") ||
+			strings.HasPrefix(accept, "application/cbor") {
 			mediatype, params, err := mime.ParseMediaType(accept)
 			if err != nil {
 				return "", nil, err

core/corehttp/gateway_handler_codec.go

@@ -0,0 +1,58 @@
+package corehttp
+
+import (
+	"context"
+	"fmt"
+	"html"
+	"net/http"
+	"time"
+
+	ipldlegacy "github.com/ipfs/go-ipld-legacy"
+	ipath "github.com/ipfs/interface-go-ipfs-core/path"
+	"github.com/ipfs/kubo/tracing"
+	"github.com/ipld/go-ipld-prime"
+	"github.com/ipld/go-ipld-prime/multicodec"
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/trace"
+)
+
+var unixEpochTime = time.Unix(0, 0)
+
+func (i *gatewayHandler) serveCodec(ctx context.Context, w http.ResponseWriter, r *http.Request, resolvedPath ipath.Resolved, contentPath ipath.Path, begin time.Time, ctype string, codec uint64) {
+	ctx, span := tracing.Span(ctx, "Gateway", "ServeCodec", trace.WithAttributes(attribute.String("path", resolvedPath.String()), attribute.String("ctype", ctype)))
+	defer span.End()
+
+	// Set Cache-Control and read optional Last-Modified time
+	modtime := addCacheControlHeaders(w, r, contentPath, resolvedPath.Cid())
+
+	// Sets correct Last-Modified header. This code is borrowed from the standard
+	// library (net/http/server.go) as we cannot use serveFile.
+	if !(modtime.IsZero() || modtime.Equal(unixEpochTime)) {
+		w.Header().Set("Last-Modified", modtime.UTC().Format(http.TimeFormat))
+	}
+
+	addContentDispositionHeader(w, r, contentPath)
+	w.Header().Set("Content-Type", ctype)
+	w.Header().Set("X-Content-Type-Options", "nosniff")
+
+	obj, err := i.api.Dag().Get(ctx, resolvedPath.Cid())
+	if err != nil {
+		webError(w, "ipfs dag get "+html.EscapeString(resolvedPath.String()), err, http.StatusInternalServerError)
+		return
+	}
+
+	universal, ok := obj.(ipldlegacy.UniversalNode)
+	if !ok {
+		webError(w, "todo", fmt.Errorf("%T is not a valid IPLD node", obj), http.StatusInternalServerError)
+		return
+	}
+	finalNode := universal.(ipld.Node)
+
+	encoder, err := multicodec.LookupEncoder(codec)
+	if err != nil {
+		webError(w, "todo", err, http.StatusInternalServerError)
+		return
+	}
+
+	_ = encoder(finalNode, w)
+}