[SOLVED] detect requests to custom protocols

detect requests to custom protocols

I have a manifest v3 chrome browser extension where I need to intercept a website doing a HTTP request to a custom protocol.

When I open Network Developer Tools on that website I can see that the website tries to do a request to internal://callback. The request is obviously (canceled) but I need a way to detect this in my extension and get a URL of that request.

I tried webRequest API but it's only capable of intercepting "standart" protocols.

only the following schemes are accessible: http://, https://, ftp://, file://, ws:// (since Chrome 58), wss:// (since Chrome 58), urn: (since Chrome 91), or chrome-extension://.

chrome.webRequest.onBeforeRequest.addListener(
  (details) => {
    console.debug("onBeforeRequest", details);

    if (details.url.includes("internal")) {
      // never executes
    }
  },
  { urls: ["<all_urls>"] },
  ["extraHeaders", "requestBody"]
);

Solution

In the end I found that the custom protocol I need is present as a redirect url in one of the redirect requests, so I was able to use that:

chrome.webRequest.onBeforeRedirect.addListener(
  (details) => {
    const { redirectUrl } = details;
    if (redirectUrl.startsWith("internal://")) {
      // ...do the thing
    }
  },
  { urls: ["<all_urls>"] }
);