Merge pull request ipfs/kubo#2696 from ipfs/feature/Offline-2393

Offline daemon mode

This commit was moved from ipfs/kubo@6a894d6

gateway/core/corehttp/gateway_handler.go

@@ -159,7 +159,12 @@ func (i *gatewayHandler) getOrHeadHandler(w http.ResponseWriter, r *http.Request
 	}
 
 	nd, err := core.Resolve(ctx, i.node, path.Path(urlPath))
-	if err != nil {
+	// If node is in offline mode the error code and message should be different
+	if err == core.ErrNoNamesys && !i.node.OnlineMode() {
+		w.WriteHeader(http.StatusServiceUnavailable)
+		fmt.Fprint(w, "Could not resolve path. Node is in offline mode.")
+		return
+	} else if err != nil {
 		webError(w, "Path Resolve error", err, http.StatusBadRequest)
 		return
 	}