[RPP] Prevent infinite loop for some inputs to handleLinkResponseHeader

Fixed: 431239629
Change-Id: I161d0391f4e5c734e14b12482e6cce40096bb3be
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/6729654
Reviewed-by: Paul Irish <[email protected]>
Commit-Queue: Paul Irish <[email protected]>
Auto-Submit: Connor Clark <[email protected]>

Author: Connor Clark

front_end/models/trace/insights/NetworkDependencyTree.test.ts

@@ -376,6 +376,12 @@ describe('generatePreconnectedOrigins', () => {
       const result = Trace.Insights.Models.NetworkDependencyTree.handleLinkResponseHeader(linkHeader);
       assert.deepEqual(result, [{url: 'https://example.com', headerText: '<https://example.com>; rel="preconnect"'}]);
     });
+
+    it('should not loop infinitely on a malformed link part at the end', () => {
+      const linkHeader = '<https://a.com>; rel=preconnect, <https://b.com';
+      const result = Trace.Insights.Models.NetworkDependencyTree.handleLinkResponseHeader(linkHeader);
+      assert.deepEqual(result, [{url: 'https://a.com', headerText: '<https://a.com>; rel=preconnect'}]);
+    });
   });
 });
 

front_end/models/trace/insights/NetworkDependencyTree.ts

@@ -429,14 +429,24 @@ export function handleLinkResponseHeader(linkHeaderValue: string): Array<{url: s
   }
   const preconnectedOrigins: Array<{url: string, headerText: string}> = [];
 
-  // const headerTextParts = linkHeaderValue.split(',');
-
   for (let i = 0; i < linkHeaderValue.length;) {
     const firstUrlEnd = linkHeaderValue.indexOf('>', i);
+    if (firstUrlEnd === -1) {
+      break;
+    }
+
     const commaIndex = linkHeaderValue.indexOf(',', firstUrlEnd);
     const partEnd = commaIndex !== -1 ? commaIndex : linkHeaderValue.length;
     const part = linkHeaderValue.substring(i, partEnd);
 
+    // This shouldn't be necessary, but we had a bug that created an infinite loop so
+    // let's guard against that.
+    // See crbug.com/431239629
+    if (partEnd + 1 <= i) {
+      console.warn('unexpected infinite loop, bailing');
+      break;
+    }
+
     i = partEnd + 1;
 
     const preconnectedOrigin = handleLinkResponseHeaderPart(part.trim());