[bug]: Missing attachment format silently sends empty fax emails

[jerryriggin]

FreePBX Version

FreePBX 17

Issue Description

Missing attachment format silently sends empty fax emails

fax 17.0.3.5: absent attachformat defaults to 'none' when 'Both' is selected — fax emails delivered with no attachment, no warning

Summary

When a user has no fax/attachformat setting, fax2mail.php coerces the missing value to 'none' and sends a fax notification email containing no fax. Nothing is logged and the email is delivered successfully, so it looks like the fax simply never arrived.

Steps to reproduce

1. Have a user with fax enabled and an email address, but no fax/attachformat row in userman_users_settings.
2. Receive a fax for that user.
3. The email arrives with no attachment. Message size in the mail log is ~750 bytes rather than tens of KB.
   Expected — a missing value inherits a usable default (the module already uses 'pdf' as its default elsewhere), or the condition is at minimum logged.
   Actual — modules/fax/bin/fax2mail.php line 52:
   $var['attachformat'] = !empty($var['attachformat']) ? $var['attachformat'] : 'none';
   then:
   case 'none':
break;

Suggested fix
Delete the 'Both' option and default to 'PDF' for consistency with the rest of the module, or log a warning when falling back to 'none' so the condition is diagnosable.
Impact
A user with fax correctly enabled receives a stream of valid, well-addressed, entirely empty fax notifications. Because delivery succeeds, mail logs look healthy and the fault presents as "faxes are not arriving" with no evidence anywhere.

Operating Environment

FreePBX 17.0.33
fax module 17.0.3.5
Asterisk 22.10.1
PHP 8.2.33
OS Debian GNU/Linux 12 (bookworm)

Relevant log output

[miken32]

Missing attachment format
...
absent attachformat defaults to 'none' when 'Both' is selected
...
When a user has no fax/attachformat setting

Is it absent or is it 'both'? Why would deleting the 'both' option be a valid solution to what sounds like a configuration problem on your system?

[jerryriggin]

It is absent when user selects 'Both' -- the field is null (or empty). It is only a configuration problem if users picks 'Both.' When selecting PDF it works fine. Haven't tested TIF. Since 'Both' doesn't work, removing the option would eliminate the possibility of misconfiguration and users won't have to spend the time I did debugging why they are not getting attachments. Or, a bunch of other code could be fixed to make 'Both' actually work,

[miken32]

Selecting Both in the dropdown works fine for me:

root@pbx [asterisk]> select user,faxenabled,faxattachformat from fax_users;
+------+------------+-----------------+
| user | faxenabled | faxattachformat |
+------+------------+-----------------+
| 1    | true       | both            |
| 2    | true       | pdf             |
| 5    | true       | pdf             |
| 6    | true       | pdf             |
+------+------------+-----------------+
4 rows in set (0.000 sec)

root@pbx [asterisk]> select * from userman_users_settings where module='fax';
+-----+--------+--------------+------+------+
| uid | module | key          | val  | type |
+-----+--------+--------------+------+------+
|   1 | fax    | attachformat | both | NULL |
|   1 | fax    | enabled      | 1    | NULL |
+-----+--------+--------------+------+------+
2 rows in set (0.000 sec)