Validate internal URLs so redirects cannot lead to 404 pages

It should probably also check the destination URL prior to sending the redirect response.

Add a checkbox to allow users to select to validate internal URLs under Configuration » Search and metadata » URL redirects » settings. the checkbox is unchecked by default.

This patch (validate_internal_urls-2327247-2.patch) can validate internal URLs, so redirects cannot lead to 404 pages when the checkbox is checked.

The patch (validate_internal_urls-2327247-4.patch) includes new changes.
1. correct the spelling error on the error message.
2. using drupal_valid_path() instead of get_headers() adds a HTTP request.

When having multilingual module on a site, the validate will fail when choosing all languages. In order to validate must renormalize redirect to node level. See patch (validate_internal_urls-2327247-5.patch) to see the extra normalize.

Last patch was incremental patch. This is the entire patch.

Reroll.

The patch in #10 is 4 years old and no longer applies to the latest 7.x-1.x-dev may be too old to reroll, but I'll add the issue tag anyway.

Checking patch redirect.admin.inc...
Hunk #1 succeeded at 492 (offset 27 lines).
Hunk #2 succeeded at 499 (offset 27 lines).
error: while searching for:
    '#description' => t('Only redirects managed by the redirect module itself will be deleted. Redirects managed by other modules will be left alone.'),
    '#disabled' => variable_get('redirect_page_cache', 0) && !variable_get('page_cache_invoke_hooks', TRUE),
  );

  $form['globals'] = array(
    '#type' => 'fieldset',

error: patch failed: redirect.admin.inc:636
error: redirect.admin.inc: patch does not apply

Looks good.

+++ b/redirect.admin.inc
@@ -508,6 +507,13 @@ function redirect_element_validate_redirect($element, &$form_state) {
+      form_error($element, t('The redirect path %value is not valid.', array('%value' => $value)));

I guess this error message should be more descriptive. Is not really clearly describe for the user why this URL is not valid.

I think it is written that way to duplicate an error a few lines up.

Anyway, how about "The redirect path %value does not exist."?

+1. I think this one is more correct. The message is related to existence check that trying to prevent causes of 404 error.

Any chance/interest in porting this to the D8 version? I didn't see a similar D8 issue in the issue queue.

#12 with message like in #15.