TLDR: When using horde/mail_autoconfig or other features using pear/net_dns2 under PHP 8.x, use the “master” branch or wait for a release of version 1.5.3 or higher.
While upgrading the Maintaina Horde codebase for PHP 8.1, I stumbled upon a problem:
[Sun May 15 12:15:15.026499 2022] [php:error] [pid 156] [client 172.23.0.1:43894] PHP Fatal error: Uncaught ValueError: fread(): Argument #2 ($length) must be greater than 0 in /srv/www/horde/vendor/pear/net_dns2/Net/DNS2/Cache/File.php:147\nStack trace:\n#0 /srv/www/horde/vendor/pear/net_dns2/Net/DNS2/Cache/File.php(147): fread()\n#1 [internal function]: Net_DNS2_Cache_File->__destruct()\n#2 {main}\n thrown in /srv/www/horde/vendor/pear/net_dns2/Net/DNS2/Cache/File.php on line 147, referer: http://localhost/horde/admin/config/config.php
It turns out Net_DNS2 as of latest version 1.5.2 has a problem in its filesystem cache when run under PHP 8.x – it tries to read the cache file content even if the file size is 0 or the file does not yet exist. In PHP 8.x this yields a ValueError because reading with a length 0 should not be attempted.
Mike Pultz, the maintainer of Net_DNS2 already has a fix in his master branch. I have kindly asked him to release a stable version with this fix. However I understand it may take a while or may not be very high on the daily priority list of todos. I am not sure what other changes the master branch contains which might impair its usefulness to your use case. I am hesitant to put work into a problem somebody else already fixed. I will only provide a downstream-packaged version in case no update happens within reasonable time.
Thank you for this post.
As Debian 12 with PHP 8.2 has become stable in the meantime, an updated version of Net_DNS2 is still missing – I guess this bugs a lot more people now.
Do you mind pushing the maintainer of Net_DNS2?
I did so once or twice – we will probably have to do a downstream fork as seen in https://horde-satis.maintaina.com/#net_dns2