isPermittedRedirect function

bool isPermittedRedirect(Uri original, Uri redirect)

Check if a redirect is permitted.

Implementation

bool isPermittedRedirect(Uri original, Uri redirect) {
  // Must maintain same protocol
  if (original.scheme != redirect.scheme) return false;

  // No credentials in redirect
  if (redirect.userInfo.isNotEmpty) return false;

  // Same port
  if (original.port != redirect.port) return false;

  // Hostname can only differ by www prefix
  final origHost = original.host.toLowerCase();
  final redirHost = redirect.host.toLowerCase();
  if (origHost != redirHost) {
    final origWithoutWww = origHost.startsWith('www.')
        ? origHost.substring(4)
        : origHost;
    final redirWithoutWww = redirHost.startsWith('www.')
        ? redirHost.substring(4)
        : redirHost;
    if (origWithoutWww != redirWithoutWww) return false;
  }

  return true;
}