Bug #64948 [Com]: FILTER_VALIDATE_URL does not see urls with underscores as valid URLs.

Edit report at https://bugs.php.net/bug.php?id=64948&edit=1 ID: 64948 Comment by: rich at social5 dot com Reported by: neclimdul at gmail dot com Summary: FILTER_VALIDATE_URL does not see urls with underscores as valid URLs. Status: Open Type: Bug Package: Filter related Operating System: Ubuntu PHP Version: 5.4.15 Block user comment: N Private report: N New Comment: The very Stack Overflow link aharvey@php.net referenced seems to suggest that FILTER_VALIDATE_URL *should* allow underscores, does it not? Regardless, ultimately, FILTER_VALIDATE_URL is used "in the wild" to verify whether or not accessing a URL will load a web resource. There certainly *are* many sites that use underscores in both the main domain as well as the subdomain. Regardless of the "lawyer material" (which one could argue is in favor of "allowing" underscores, anyway), doesn't it make sense to have FILTER_VALIDATE_URL reflect URLs that are actually used? This means that FILTER_VALIDATE_URL is useless for us since it causes our system to reject customers that happen to have an underscore in their URL. Unless this bug is fixed, we'll have to implement a separate solution that will allow the underscore-laden URLs. This doesn't sound like the best solution to me. Wouldn't you agree? Previous Comments: ------------------------------------------------------------------------ [2013-05-30 17:46:40] aharvey@php.net This is a tricky one. I think the current behaviour is technically correct here, but I don't particularly want to summarily close this either. Technically speaking, host names can't include underscores. http://stackoverflow.com/a/2183140 links to the various RFCs that define this — domain names (such as those used in SRV records) can contain underscores, but host names have a more restrictive character set. That said, RFC 3986 (which is presumably what a URL validation routine is ultimately beholden to) is specified more loosely to cover non-DNS name registries. Hosts are reg-name elements there, which allows percent encoded characters, hyphens, dots, underscores, tildes, and a range of characters defined as sub-delims. Given that underscores do have implementation issues in the wild (IE's cookie issues, for instance), my inclination is to leave this, as I said at the start, but I'd like a second opinion. tl;dr: RFC lawyer material; probably Won't Fix; need a second opinion. ------------------------------------------------------------------------ [2013-05-30 14:59:10] neclimdul at gmail dot com Description: ------------ FILTER_VALIDATE_URL does not see urls with underscores as valid URLs. Underscores are however valid and common in urls in the wild. Test script: --------------- $url = 'http://foo_bar.example.com'; var_dump(filter_var($url, FILTER_VALIDATE_URL)); Expected result: ---------------- string(26) "http://foo_bar.example.com" Actual result: -------------- bool(false) ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=64948&edit=1