54 lines
1.2 KiB
Plaintext
54 lines
1.2 KiB
Plaintext
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#!/usr/bin/perl
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=head1 NAME
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check_loop - Detect mail loops
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=head1 DESCRIPTION
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This plugin detects loops by counting "Received" and "Delivered-To"
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header lines. It's a kluge but it duplicates what qmail-smtpd does,
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and it does at least prevent messages from looping forever.
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=head1 CONFIGURATION
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Takes one optional parameter, the maximum number of "hops" ("Received"
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and lines plus "Delivered-To" lines) allowed. The default is 100, the
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same as in qmail-smtpd.
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=head1 AUTHOR
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Written by Keith C. Ivey
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=head1 LICENSE
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Released to the public domain, 17 June 2005.
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=cut
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sub register {
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my ($self, $qp, @args) = @_;
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$self->register_hook("data_post", "check_loop");
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$self->{_max_hops} = $args[0] || 100;
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if ( $self->{_max_hops} !~ /^\d+$/ ) {
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$self->log(LOGWARN, "Invalid max_hops value -- using default");
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}
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$self->log(LOGWARN, "Ignoring additional arguments") if @args > 1;
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}
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sub check_loop {
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my ($self, $transaction) = @_;
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my $hops = 0;
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$hops++ for $transaction->header->get('Received'),
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$transaction->header->get('Delivered-To');
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if ( $hops >= $self->{_max_hops} ) {
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return DENY, "Too many hops. This message is looping.";
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}
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return DECLINED;
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}
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