Add validation for the mailpath POST parameter to prevent command injection
attacks. The path is validated to only allow alphanumeric characters,
underscores, dashes, forward slashes, and dots.
- Required mailpath when protocol is "sendmail"
- Validates format for all non-empty mailpath values
- Blocks common injection vectors: ; | & ` $() spaces newlines
- Added mailpath_invalid translation to all 43 language files
- Simplified validation logic to avoid redundant conditions
Files changed:
- app/Controllers/Config.php: Add regex validation with protocol check
- app/Language/*/Config.php: Add mailpath_invalid error message (43 languages)
- tests/Controllers/ConfigTest.php: Unit tests for validation
