wip: play with dag-cbor and dag-json

core/corehttp/gateway_handler.go

@@ -26,6 +26,7 @@ import (
 	coreiface "github.com/ipfs/interface-go-ipfs-core"
 	ipath "github.com/ipfs/interface-go-ipfs-core/path"
 	routing "github.com/libp2p/go-libp2p/core/routing"
+	mc "github.com/multiformats/go-multicodec"
 	prometheus "github.com/prometheus/client_golang/prometheus"
 	"go.opentelemetry.io/otel/attribute"
 	"go.opentelemetry.io/otel/trace"
@@ -430,6 +431,14 @@ func (i *gatewayHandler) getOrHeadHandler(w http.ResponseWriter, r *http.Request
 		carVersion := formatParams["version"]
 		i.serveCAR(r.Context(), w, r, resolvedPath, contentPath, carVersion, begin)
 		return
+	case "application/vnd.ipld.dag-json":
+		logger.Debugw("serving dag-json", "path", contentPath)
+		i.serveJSON(r.Context(), w, r, resolvedPath, begin, "application/vnd.ipld.dag-json", uint64(mc.DagJson))
+		return
+	case "application/vnd.ipld.dag-cbor":
+		logger.Debugw("serving dag-cbor", "path", contentPath)
+		i.serveJSON(r.Context(), w, r, resolvedPath, begin, "application/vnd.ipld.dag-cbor", uint64(mc.DagCbor))
+		return
 	default: // catch-all for unsuported application/vnd.*
 		err := fmt.Errorf("unsupported format %q", responseFormat)
 		webError(w, "failed respond with requested content type", err, http.StatusBadRequest)
@@ -859,6 +868,10 @@ func customResponseFormat(r *http.Request) (mediaType string, params map[string]
 			return "application/vnd.ipld.raw", nil, nil
 		case "car":
 			return "application/vnd.ipld.car", nil, nil
+		case "dag-json":
+			return "application/vnd.ipld.dag-json", nil, nil
+		case "dag-cbor":
+			return "application/vnd.ipld.dag-cbor", nil, nil
 		}
 	}
 	// Browsers and other user agents will send Accept header with generic types like:

core/corehttp/gateway_handler_json.go

@@ -0,0 +1,44 @@
+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/ipld/go-ipld-prime"
+	"github.com/ipld/go-ipld-prime/multicodec"
+)
+
+// serveCAR returns a CAR stream for specific DAG+selector
+func (i *gatewayHandler) serveJSON(ctx context.Context, w http.ResponseWriter, r *http.Request, resolvedPath ipath.Resolved, begin time.Time, ctype string, codec uint64) {
+	// ctx, span := tracing.Span(ctx, "Gateway", "ServeCAR", trace.WithAttributes(attribute.String("path", resolvedPath.String())))
+	// defer span.End()
+	// ctx, cancel := context.WithCancel(ctx)
+	// defer cancel()
+
+	obj, err := i.api.Dag().Get(r.Context(), 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
+	}
+
+	w.Header().Set("Content-Type", ctype)
+	_ = encoder(finalNode, w)
+}