Bug: auto_link() fails to include trailing slashes in URLs

[corenominal]

PHP Version

8.2

CodeIgniter4 Version

4.5.4

CodeIgniter4 Installation Method

Composer (using codeigniter4/appstarter)

Which operating systems have you tested for this bug?

Linux

Which server did you use?

apache

Database

No response

What happened?

Using the URL Helper auto_link() function to automatically turn URLs contained in a string into links/HTML anchor elements. If the last character of the URL is a /, it is not included in either the anchor href value or text value.

Steps to Reproduce

Input:

$string = 'This is a test link to https://example.com/.';
$html = auto_link($string);
echo $html;

Output:

This is a test link to <a href="https://example.com">https://example.com</a>/.

Expected Output

This is a test link to <a href="https://example.com/">https://example.com/</a>.

Anything else?

I came across this as it seems that the default behaviour of Chrome and Firefox is to include the trailing slash when copying the URL from the browser's address bar. I tend to do this a lot and noticed that the auto_link() function always missed the trailing slash when creating anchor elements.

[kenjis]

#158 The first commit of auto_link().

The regex is not changed from the beginning.

preg_match_all('#(\w*://|www\.)[^\s()<>;]+\w#i', $str, $matches, PREG_OFFSET_CAPTURE | PREG_SET_ORDER)

But the regex in CI3 is the following:

preg_match_all('#(\w*://|www\.)[a-z0-9]+(-+[a-z0-9]+)*(\.[a-z0-9]+(-+[a-z0-9]+)*)+(/([^\s()<>;]+\w)?/?)?#i', $str, $matches, PREG_OFFSET_CAPTURE | PREG_SET_ORDER)

It seems it was changed in bcit-ci/CodeIgniter@8c9e510.
But before the change, there was already /? (not …+\w#i but …+\w/?#i) in the end.

[corenominal]

Thanks for looking into this. I messed up with my PR, apologies.

[kenjis]

No problem. It is almost impossible for anyone to send a perfect PR at first.

I sent #9169. Please check.

[kenjis]

@codeigniter4/core-team
This is clearly documented, but why auto_link() recognizes a string starting with ://?

The link <a href="://codeigniter.com">://codeigniter.com</a> does not seem to work.
If I put the link in the Welcome page, the URL will be http://localhost:8080/://codeigniter.com.

Note
The only URLs recognized are those that start with www. or with ://.
https://codeigniter4.github.io/CodeIgniter4/helpers/url_helper.html#auto_link

CodeIgniter4/tests/system/Helpers/URLHelper/MiscUrlTest.php

Lines 525 to 526 in ffd1b68

	'This one: ://codeigniter.com must not break this one: http://codeigniter.com',
	'This one: <a href="://codeigniter.com">://codeigniter.com</a> must not break this one: <a href="http://codeigniter.com">http://codeigniter.com</a>',

[michalsn]

I guess that :// would support cases for: https, http, ftp, etc.

[kenjis]

Yes, 'test abc://www.codeigniter.com test' will be 'test <a href="abc://www.codeigniter.com">abc://www.codeigniter.com</a> test'. But it does not make sense.

[michalsn]

The range of what will "catch" on this rule is large, but thanks to this we have support for all direct links that are supported by many apps, like slack:// - https://api.slack.com/reference/deep-linking#client

[neznaika0]

Telegram API https://core.telegram.org/api/links

[kenjis]

Okay, the current behavior seems useful, and can catch unknown schemes.
But catching ://codeigniter.com does not make sense.
Should it catch [a-z0-9]+://?

[corenominal]

RFC 3986 states that the scheme component is required.

The scheme and path components are required, though the path may be empty (no characters).

I would think that it should catch [a-z0-9]+://.

[kenjis]

scheme = ALPHA *( ALPHA / DIGIT / "+" / "-" / "." )
https://datatracker.ietf.org/doc/html/rfc3986#section-3.1

[a-z][a-z0-9+\-.]*:// is better?

[michalsn]

[a-z][a-z0-9+\-.]*:// is better?

Yes.

[kenjis]

I sent #9180