Function getWithPermittedRedirects

src/tools/WebFetchTool/utils.ts:262–366

(
  url: string,
  signal: AbortSignal,
  redirectChecker: (originalUrl: string, redirectUrl: string) => boolean,
  depth = 0,
)

}

export async function getWithPermittedRedirects(
  url: string,
  signal: AbortSignal,
  redirectChecker: (originalUrl: string, redirectUrl: string) => boolean,
  depth = 0,
): Promise<AxiosResponse<ArrayBuffer> | RedirectInfo> {
  if (depth > MAX_REDIRECTS) {
    throw new Error(`Too many redirects (exceeded ${MAX_REDIRECTS})`)
  }
  try {
    return await axios.get(url, {
      signal,
      timeout: FETCH_TIMEOUT_MS,
      maxRedirects: 0,
      responseType: 'arraybuffer',
      maxContentLength: MAX_HTTP_CONTENT_LENGTH,
      headers: {
        Accept: 'text/markdown, text/html, */*',
        'User-Agent': getWebFetchUserAgent(),
      },
    })
  } catch (error) {
    if (
      axios.isAxiosError(error) &&
      error.response &&
      [301, 302, 307, 308].includes(error.response.status)
    ) {
      const redirectLocation = error.response.headers.location
      if (!redirectLocation) {
        throw new Error('Redirect missing Location header')
      }

      // Resolve relative URLs against the original URL
      const redirectUrl = new URL(redirectLocation, url).toString()

      if (redirectChecker(url, redirectUrl)) {
        // Recursively follow the permitted redirect
        return getWithPermittedRedirects(
          redirectUrl,
          signal,
          redirectChecker,
          depth + 1,
        )
      } else {
        // Return redirect information to the caller
        return {
          type: 'redirect',
          originalUrl: url,
          redirectUrl,
          statusCode: error.response.status,
        }
      }
    }

    // Detect egress proxy blocks: the proxy returns 403 with
    // X-Proxy-Error: blocked-by-allowlist when egress is restricted
    if (
      axios.isAxiosError(error) &&