Bug #64948 [Opn]: 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 Updated by: yohgaki@php.net 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: 7.2 Block user comment: N Private report: N New Comment: Hostname shouldn't have "_". However, NETBIOS allows "_" in hostname. DomainKeys/etc use "_" to distinguish service name and hostname. This isn't a bug, but feature request for additional option like FILTER_VALIDATE_URL_WITH_UNDERSCORE or FILTER_VALIDATE_SERVICE_URL. Previous Comments: ------------------------------------------------------------------------ [2018-10-16 16:05:20] spam2 at rhsoft dot net yeah they are somehow supported then get MSIE and try to verify a web-app working on it too you developed with chrome/firefox and wonder about all sorts of randomly lost cookies and session errors my co-worker repeatly wasted hours by add a hostname with underscore to /etc/hosts on his development machine and then searching issues which would not have happened by follow RFC's just becaus some fools ignore RFCs makes it not a good idea to follow ------------------------------------------------------------------------ [2018-10-16 16:02:42] requinix@php.net That URL clearly shows that underscores are supported. At least in my browser. Whether RFCs technically allow for it or not is besides the point now. I think FILTER_VALIDATE_URL should allow underscores. ------------------------------------------------------------------------ [2018-10-16 09:34:20] spam2 at rhsoft dot net so blame that fool, even wikipedia knows https://en.wikipedia.org/wiki/Hostname The Internet standards (Requests for Comments) for protocols mandate that component hostname labels may contain only the ASCII letters 'a' through 'z' (in a case-insensitive manner), the digits '0' through '9', and the minus sign ('-'). The original specification of hostnames in RFC 952, mandated that labels could not start with a digit or with a minus sign, and must not end with a minus sign. However, a subsequent specification (RFC 1123) permitted hostname labels to start with digits. No other symbols, punctuation characters, or white space are permitted. While a hostname may not contain other characters, such as the underscore character (_), other DNS names may contain the underscore.[4][5] Systems such as DomainKeys and service records use the underscore as a means to assure that their special character is not confused with hostnames ------------------------------------------------------------------------ [2018-10-16 09:29:34] luke at reviews dot co dot uk As requested, the below URL is what caused me to stumble across this "bug" https://electrictobacconist_co_uk.secure-cdn.visualsoft.co.uk/images/gamucci-refills-p86-15678_image.jpg ------------------------------------------------------------------------ [2018-10-15 16:31:59] requinix@php.net @neclimdul: You're looking at RFC 2396 which was obsoleted by RFC 3986. If you look there you'll see the grammar still allows it, however it comes with a caveat: > A registered name intended for lookup in the DNS uses the syntax defined in > Section 3.5 of [RFC1034] and Section 2.1 of [RFC1123]. As has been said, the situation for underscores is complicated and somewhat contradictory, both for URIs and for DNS. Some RFCs allow them and others do not. I'd give a primer but we're talking about more than just a couple RFCs involved in this. Basically, URIs allow underscores in hostnames by way of the grammar but with the caveat I mentioned above, DNS as a whole does not allow it for labels according to that grammar, yet some DNS record types do allow them (notably SRV and TXT). But remember here we're specifically talking about URLs. Can anyone link a functioning *website* that uses an underscore in the domain name? I'm thinking we tie the status of this request to that: if there is one and it works in browsers then we allow underscores, otherwise not. ------------------------------------------------------------------------ The remainder of the comments for this report are too long. To view the rest of the comments, please view the bug report online at https://bugs.php.net/bug.php?id=64948 -- Edit this bug report at https://bugs.php.net/bug.php?id=64948&edit=1