#!/usr/local/bin/perl

#Written by Nick
#This script is meant to be called from Zachary Bedell's
# qmail-smtpd chkusr patch located at 
# https://mail.adirondack.net/phpwebsite/index.php?module=pagemaster&PAGE_user_op=view_page&PAGE_id=20
#
#For more information about my programming, or this script
#Please visit my web site at http://illx.org

#Currently, this script supports checking local system users
#and users in Qmail's users/assign (which are 'virtual' users
#but Qmail just turns them back into local users anyhow)
 
#email address is our argument (lower-case it to be safe)
my $email = lc($ARGV[0]); 

#PLEASE NOTE: The following files must be readable by this script:
# /etc/passwd
# /var/qmail/control/locals
# /var/qmail/control/virtualdomains
# /var/qmail/users/assign

#exit 0 returns a failure (non-existant user in to qmail-smtpd)
#exit 1 returns a success (the  user exists, 
#                          and lets qmail-smtpd know its good)
#exit 2 For an error generated by this program.
#       An error like this will generate a 
#       421 unable to verify recipient (#4.3.0)  from qmail-smtpd

#exit 0 if no email address given
unless($email) { exit(0); }

#split out the username and domain name
my ($user,$domain) = split('@', $email);

#exit 0 if the user or domain is not present
unless($user or $domain) { exit(0); }

#If /var/qmail/control/locals and
#/var/qmail/control/virtualdomains don't exist, we
#exit 2, because we check the locals file for /etc/passwd users
#and we check the users/assign file for virtualdomain users
unless(-e '/var/qmail/control/locals' &&
       -e '/var/qmail/control/virtualdomains') {
    exit(2);
}

#First, check local users
# open up the /var/qmail/control/locals file
# and grab all of the domains
# NOTE: I lower-case all data retrieved from the qmail files
#       just to be safe.
my @locals = ();
open(LOCALS, '/var/qmail/control/locals') or exit(2);
while(<LOCALS>) {
    chomp;
    next unless $_;
    push(@locals, lc($_));
}
close(LOCALS);

# get our system users from /etc/passwd
my @sysusers = ();
open(PASSWD, '/etc/passwd') or exit(2);
while(<PASSWD>) {
    chomp;
    next unless $_;
    my @fields = split(':', $_);
    push(@sysusers, lc($fields[0]));
}
close(PASSWD);

# get our qmail alias users from /var/qmail/alias
my @aliasusers = ();
opendir(ALIASES, "/var/qmail/alias") 
    or die "Unable to open the directory '/var/qmail/alias': $!\n";
while(my $file = readdir(ALIASES)) {
    next if $file eq '.';
    next if $file eq '..';
    next unless $file =~ /\.qmail-/;
    my @s = split('-', $file);
    push(@aliasusers, $s[1]);
}
closedir(ALIASES);

# go through our system users for local domains
foreach my $u (@sysusers) {
    if($u eq $user) { #our user exists, continue on to check local domain
	foreach my $d (@locals) {
	    if($d eq $domain) { #our domain exists, they exist!
		exit(1);
	    }
	}
    }
}

# go through our alias users for local domains
foreach my $u (@aliasusers) {
    if($u eq $user) { #our user exists, continue on to check local domain
	foreach my $d (@locals) {
	    if($d eq $domain) { #our domain exists, they exist!
		exit(1);
	    }
	}
    }
}

# so they didn't exist in /etc/passwd, go on to check our virtualdomains

#Second, check users against qmail's virtualdomains                                                           
# grab our virtual domains                                                                                    
my %virtdoms = ();
open(VDS, '/var/qmail/control/virtualdomains') or exit(2);
while(<VDS>) {
    chomp;
    next unless $_;
    my ($dom,$id) = split(':', $_);
    $dom = lc($dom);
    $id  = lc($id);
    $virtdoms{$dom} = $id;
}
close(VDS);

# then, grab all of our local qmail users                                                                     
my @qmailusers = ();
open(ASSIGN, '/var/qmail/users/assign') or exit(2);
while(<ASSIGN>) {
    chomp;
    #strip off all spacesa
    $_ =~ s/\s//g;
    next unless $_;

    my @fields = split(':', $_);
    my @chars = split(//, $fields[0]);
    next if $chars[0] eq '+'; #we skip all wildcards (for now, maybe I'll get around to it)
    next if $chars[0] eq '.'; #skip the dot at the end
    #remove the first char
    shift(@chars);

    push(@qmailusers, lc(join('', @chars)));
}
close(ASSIGN);

# go through all of the users, and see if they exist                                                          
foreach my $qmu (@qmailusers) {
    #then, go through all the virtdomains per user, prepending the 
    #extension on to the username to make it local, and check it against users/assign
    foreach my $dom (keys %virtdoms) {
	#get the prefix of the username
	my $userprefix = substr($qmu, 0, length($virtdoms{$dom}));

	#if we see our domain as part of the qmail user prepended domain
	if($virtdoms{$dom} eq $userprefix) {
	    #get just the username from the qmail username
	    my $uname = substr($qmu, length($virtdoms{$dom})+1, length($qmu));

	    #make a valid email address out of it
	    my $em = "$uname\@$dom";;

	    #if it matches, it exists in the users/assign
	    if($em eq $email) {
		exit(1);
	    }		
	}
    }
}

#HERE, you could call vpopmail or vmailmgr if you wanted.
#I've just covered the basics.

#If we're here at the end, they didn't exist
exit(0);