---
name: "Courier::Filter::Util"
section: "3pm"
platform: "linux"
package: "courier-filter-perl"
version: "0.200+ds-6"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/Courier::Filter::Util"
---

# Courier::Filter::Util(3pm)

Utility class used by the Courier::Filter framework

## NAME

Courier::Filter::Util - Utility class used by the Courier::Filter framework

## SYNOPSIS

```
    use Courier::Filter::Util qw(
        ipv4_address_pattern
        ipv6_address_pattern
        loopback_address_pattern
    );

    $message->remote_host =~ / ^ (?: ::ffff: )? $(\ipv4_address_pattern} $ /x;
    $message->remote_host =~ / ^ $(\ipv6_address_pattern} $ /x;
    $message->remote_host =~ / ^ ${\loopback_address_pattern} $ /x;
```

## DESCRIPTION

**Courier::Filter::Util** is Courier::Filter's utility class.

### Constants

The following constants are provided:

- **ipv4\_address\_pattern**

  A regular expression matching an IPv4 address in "dotted decimal" notation.

- **ipv6\_address\_pattern**

  A regular expression matching an IPv6 address in full RFC 4291 syntax.

- **loopback\_address\_pattern**

  A regular expression matching an IPv4 or IPv6 loopback address (`"127.n.n.n"`, `"::ffff:127.n.n.n.n"`, `"::1"`).

## SEE ALSO

Courier::Filter.

For AVAILABILITY, SUPPORT, and LICENSE information, see Courier::Filter::Overview.

## AUTHOR

Julian Mehnle \<julian@mehnle.net\>