fix(gateway): handle streaming errors, IPIP 332

core/corehttp/gateway_handler.go

@@ -1104,3 +1104,26 @@ func (i *gatewayHandler) setCommonHeaders(w http.ResponseWriter, r *http.Request
 
 	return nil
 }
+
+// abortConn forcefully closes an HTTP connection, leading to a network error on the
+// client side. This is a way of showing the client that there was an error while streaming
+// the contents since there are no good ways of showing an error during a stream.
+func abortConn(w http.ResponseWriter) {
+	hj, ok := w.(http.Hijacker)
+	if !ok {
+		// If we could not Hijack the connection (such as in HTTP/2.x) connections, we
+		// panic using http.ErrAbortHandler, which aborts the response.
+		// https://pkg.go.dev/net/http#ErrAbortHandler
+		panic(http.ErrAbortHandler)
+	}
+
+	conn, _, err := hj.Hijack()
+	if err != nil {
+		panic(http.ErrAbortHandler)
+	}
+
+	err = conn.Close()
+	if err != nil {
+		panic(http.ErrAbortHandler)
+	}
+}

core/corehttp/gateway_handler_block.go

@@ -46,7 +46,12 @@ func (i *gatewayHandler) serveRawBlock(ctx context.Context, w http.ResponseWrite
 
 	// ServeContent will take care of
 	// If-None-Match+Etag, Content-Length and range requests
-	_, dataSent, _ := ServeContent(w, r, name, modtime, content)
+	_, dataSent, err := ServeContent(w, r, name, modtime, content)
+
+	if err != nil {
+		abortConn(w)
+		return
+	}
 
 	if dataSent {
 		// Update metrics

core/corehttp/gateway_handler_car.go

@@ -76,11 +76,7 @@ func (i *gatewayHandler) serveCAR(ctx context.Context, w http.ResponseWriter, r
 	car := gocar.NewSelectiveCar(ctx, store, []gocar.Dag{dag}, gocar.TraverseLinksOnlyOnce())
 
 	if err := car.Write(w); err != nil {
-		// We return error as a trailer, however it is not something browsers can access
-		// (https://github.com/mdn/browser-compat-data/issues/14703)
-		// Due to this, we suggest client always verify that
-		// the received CAR stream response is matching requested DAG selector
-		w.Header().Set("X-Stream-Error", err.Error())
+		abortConn(w)
 		return
 	}
 

core/corehttp/gateway_handler_tar.go

@@ -79,14 +79,6 @@ func (i *gatewayHandler) serveTAR(ctx context.Context, w http.ResponseWriter, r
 
 	// The TAR has a top-level directory (or file) named by the CID.
 	if err := tarw.WriteFile(file, rootCid.String()); err != nil {
-		w.Header().Set("X-Stream-Error", err.Error())
-		// Trailer headers do not work in web browsers
-		// (see https://github.com/mdn/browser-compat-data/issues/14703)
-		// and we have limited options around error handling in browser contexts.
-		// To improve UX/DX, we finish response stream with error message, allowing client to
-		// (1) detect error by having corrupted TAR
-		// (2) be able to reason what went wrong by instecting the tail of TAR stream
-		_, _ = w.Write([]byte(err.Error()))
-		return
+		abortConn(w)
 	}
 }

core/corehttp/gateway_handler_unixfs_dir.go

@@ -209,7 +209,7 @@ func (i *gatewayHandler) serveDirectory(ctx context.Context, w http.ResponseWrit
 	logger.Debugw("request processed", "tplDataDNSLink", dnslink, "tplDataSize", size, "tplDataBackLink", backLink, "tplDataHash", hash)
 
 	if err := listingTemplate.Execute(w, tplData); err != nil {
-		internalWebError(w, err)
+		abortConn(w)
 		return
 	}
 

core/corehttp/gateway_handler_unixfs_file.go

@@ -94,7 +94,12 @@ func (i *gatewayHandler) serveFile(ctx context.Context, w http.ResponseWriter, r
 
 	// ServeContent will take care of
 	// If-None-Match+Etag, Content-Length and range requests
-	_, dataSent, _ := ServeContent(w, r, name, modtime, content)
+	_, dataSent, err := ServeContent(w, r, name, modtime, content)
+
+	if err != nil {
+		abortConn(w)
+		return
+	}
 
 	// Was response successful?
 	if dataSent {

test/sharness/t0122-gateway-tar.sh

@@ -76,8 +76,7 @@ test_expect_success "Add CARs with relative paths to test with" '
 '
 
 test_expect_success "GET TAR with relative paths outside root fails" '
-  curl -o - "http://127.0.0.1:$GWAY_PORT/ipfs/$OUTSIDE_ROOT_CID?format=tar" > curl_output_filename &&
-  test_should_contain "relative UnixFS paths outside the root are now allowed" curl_output_filename
+  ! curl "http://127.0.0.1:$GWAY_PORT/ipfs/$OUTSIDE_ROOT_CID?format=tar"
 '
 
 test_expect_success "GET TAR with relative paths inside root works" '