#! /usr/bin/perl -w
require '/usr/local/news/lib/innshellvars.pl';

##  $Id: controlchan.in,v 1.7 2002/11/21 00:03:15 vinocur Exp $
##
##  Channel feed program to route control messages to an appropriate handler.
##
##  Copyright 2001 by Marco d'Itri <md@linux.it>
##
##  Redistribution and use in source and binary forms, with or without
##  modification, are permitted provided that the following conditions
##  are met:
##
##   1. Redistributions of source code must retain the above copyright
##      notice, this list of conditions and the following disclaimer.
##
##   2. Redistributions in binary form must reproduce the above copyright
##      notice, this list of conditions and the following disclaimer in the
##      documentation and/or other materials provided with the distribution.
##
##  Give this program its own newsfeed.  Make sure that you've created
##  the newsgroup control.cancel so that you don't have to scan through
##  cancels, which this program won't process anyway.
##
##  Make a newsfeeds entry like this:
##
##  controlchan!\
##     :!*,control,control.*,!control.cancel\
##     :Tc,Wnsm\
##     :@prefix@/bin/controlchan

require 5.004_03;
use strict;

delete @ENV{'IFS', 'CDPATH', 'ENV', 'BASH_ENV'};

# globals
my ($cachedctl, $curmsgid);
my $lastctl = 0;
my $use_syslog = 0;
my $debug = 0;

# setup logging ###########################################################
# do not log to syslog if stderr is connected to a console
if (not -t 2) {
    eval { require INN::Syslog; import INN::Syslog; $use_syslog = 1; };
    eval { require Sys::Syslog; import Sys::Syslog; $use_syslog = 1; }
        unless $use_syslog;
}

if ($use_syslog) {
    eval "sub Sys::Syslog::_PATH_LOG { '/dev/log' }" if $^O eq 'dec_osf';
    Sys::Syslog::setlogsock('unix') if $^O =~ /linux|dec_osf/;
    openlog('controlchan', 'pid', $inn::syslog_facility);
}
logmsg('starting');

# load modules from the control directory #################################
opendir(CTL, $inn::controlprogs)
    or logdie("Cannot open $inn::controlprogs", 'crit');
foreach (readdir CTL) {
    next if not /^([a-z\.]+\.pl)$/ or not -f "$inn::controlprogs/$_";
    eval { require "$inn::controlprogs/$1" };
    if ($@) {
        $@ =~ s/\n/  /g;
        logdie($@, 'crit');
    }
    logmsg("loaded $inn::controlprogs/$1", 'debug');
}
closedir CTL;

# main loop ###############################################################
while (<STDIN>) {
    chop;
    my ($token, $sitepath, $msgid) = split(/\s+/, $_);
    next if not defined $token;
    $sitepath ||= '';
    $curmsgid = $msgid || '';

    my $artfh = open_article($token);
    next if not defined $artfh;

    # suck in headers and body, normalize the strange ones
    my (@headers, @body, %hdr);
    if (not parse_article($artfh, \@headers, \@body, \%hdr)) {
        close $artfh;
        next;
    }
    close $artfh or logdie('sm died with status ' . ($? >> 8));

    next if not exists $hdr{control};

    $curmsgid = $hdr{'message-id'};
    my $sender = cleanaddr($hdr{sender} || $hdr{from});
    my $replyto = cleanaddr($hdr{'reply-to'} || $hdr{from});

    my (@progparams, $progname);
    if ($hdr{control} =~ /\s/) {
        $hdr{control} =~ /^(\S+)\s+(.+)?/;
        $progname = lc $1;
        @progparams = split(/\s+/, lc $2) if $2;
    } else {
        $progname = lc $hdr{control};
    }

    next if $progname eq 'cancel';

    if ($progname !~ /^([a-z]+)$/) {
        logmsg("Naughty control in article $curmsgid ($progname)");
        next;
    }
    $progname = $1;

    # Do we want to process the message?  Let's check the permissions.
    my ($action, $logname, $newsgrouppats) =
        ctlperm($progname, $sender, $progparams[0],
                $token, \@headers, \@body);

    next if $action eq 'drop';

    if ($action eq '_pgpfail') {
        my $type = '';
        if ($progname and $progname eq 'newgroup') {
            if ($progparams[1] and $progparams[1] eq 'moderated') {
                $type = 'm ';
            } else {
                $type = 'y ';
            }
        }
        logmsg("skipping $progname $type$sender"
            . "(pgpverify failed) in $curmsgid");
        next;
    }

    # used by checkgroups. Convert from perl regexp to grep regexp.
    if (local $_ = $newsgrouppats) {
        s/\$\|/|/g;
        s/[^\\]\.[^*]/?/g;
        s/\$//;
        s/\.\*/*/g;
        s/\\([\$\+\.])/$1/g;
        $progparams[0] = $_;
    }

    # find the appropriate module and call it
    my $subname = "control_$progname";
    my $subfind = \&$subname;
    if (not defined &$subfind) {
        if ($logname) {
            logger($logname, "Unknown control message by $sender",
                \@headers, \@body);
        } else {
            logmsg("Unknown \"$progname\" control by $sender");
        }
        next;
    }

    my $approved = $hdr{approved} ? 1 : 0;
    logmsg("$subname, " . join(' ', @progparams)
        . " $sender $replyto $token, $sitepath, $action"
        . ($logname ? "=$logname" : '') .", $approved");

    &$subfind(\@progparams, $sender, $replyto, $sitepath,
        $action, $logname, $approved, \@headers, \@body);
}

closelog() if $use_syslog;
exit 0;

print $inn::most_logs.$inn::syslog_facility.$inn::mta.
    $inn::newsmaster.$inn::locks; # lint food

# misc functions ##########################################################
sub parse_article {
    my ($artfh, $headers, $body, $hdr) = @_;
    my $h;
    my %uniquehdr = map { $_ => 1 }    qw(date followup-to from message-id
        newsgroups path reply-to subject sender);

    while (<$artfh>) {
        chop;
        last if /^$/;
        push @$headers, $_;
        if (/^(\S+):\s+(.+)/) {
            $h = lc $1;
            if (exists $hdr->{$h}) {
                if (exists $uniquehdr{$h}) {
                    logmsg("Multiple $1 headers in article $curmsgid");
                    return 0;
                }
                $hdr->{$h} .= ' ' . $2;
            } else {
                $hdr->{$h} = $2;
            }
            next;
        } elsif (/^\s+(.+)/) {
            if (defined $h) {
                $hdr->{$h} .= ' ' . $1;
                next;
            }
        }
        logmsg("Broken headers in article $curmsgid");
        return 0;
    }

    # article is empty or does not exist
    return 0 if not @$headers;

    chop (@$body = <$artfh>);
    return 1;
}

# Strip a mail address, innd-style.
sub cleanaddr {
    local $_ = shift;
    s/(\s+)?\(.*\)(\s+)?//g;
    s/.*<(.*)>.*/$1/;
    s/[^-a-zA-Z0-9+_.@%]/_/g;    # protect MTA
    s/^-/_/;                    # protect MTA
    return $_;
}

# Read and cache control.ctl.
sub readctlfile {
    my $mtime = (stat($inn::ctlfile))[9];
    return $cachedctl if $lastctl == $mtime;    # mtime has not changed.
    $lastctl = $mtime;

    my @ctllist;
    open(CTLFILE, $inn::ctlfile)
        or logdie("Cannot open $inn::ctlfile", 'crit');
    while (<CTLFILE>) {
        chop;
        # Not a comment or blank? Convert wildmat to regex
        next if not /^(\s+)?[^\#]/ or /^$/;
        if (not /:(?:doit|doifarg|drop|log|mail|verify-.*)(?:=.*)?$/) {
            s/.*://;
            logmsg("$_ is not a valid action for control.ctl", 'err');
            next;
        }
        # Convert to a : separated list of regexps
        s/^all:/*:/i;
        s/([\$\+\.])/\\$1/g;
        s/\*/.*/g;
        s/\?/./g;
        s/(.*)/^$1\$/;
        s/:/\$:^/g;
        s/\|/\$|^/g;
        push @ctllist, $_;
    }
    close CTLFILE;

    logmsg('warning: control.ctl is empty!', 'err') if not @ctllist;
    return $cachedctl = [ reverse @ctllist ];
}

# Parse a control message's permissions.
sub ctlperm {
    my ($type, $sender, $newsgroup, $token, $headers, $body) = @_;

    my $action = 'drop';    # default
    my ($logname, $hier);

    # newgroup and rmgroup require newsgroup names; check explicitly for that
    # here and return drop if the newsgroup is missing (to avoid a bunch of
    # warnings from undefined values later on in permission checking).
    if ($type eq 'newgroup' or $type eq 'rmgroup') {
        unless ($newsgroup) {
            return ('drop', undef, undef);
        }
    }

    my $ctllist = readctlfile();
    foreach (@$ctllist) {
        my @ctlline = split /:/;
        # 0: type  1: from@addr  2: group.*  3: action
        if ($type =~ /$ctlline[0]/ and $sender =~ /$ctlline[1]/i and
            ($type !~ /(?:new|rm)group/ or $newsgroup =~ /$ctlline[2]/)) {
            $action = $ctlline[3];
            $action =~ s/\^(.+)\$/$1/;
            $action =~ s/\\//g;
            $hier = $ctlline[2] if $type eq 'checkgroups';
            last;
        }
    }

    ($action, $logname) = split(/=/, $action);

    if ($action =~ /^verify-(.+)/) {
        my $keyowner = $1;
        if ($inn::pgpverify and $inn::pgpverify =~ /^(?:true|on|yes)$/i) {
            my $pgpresult = defined &local_pgpverify ?
                local_pgpverify($token, $headers, $body) : pgpverify($token);
            if ($keyowner eq $pgpresult) {
                $action = 'doit';
            } else {
                $action = '_pgpfail';
            }
        } else {
            $action = 'mail';
        }
    }

    return ($action, $logname, $hier);
}

# Write stuff to a log or send mail to the news admin.
sub logger {
    my ($logfile, $message, $headers, $body) = @_;

    if ($logfile eq 'mail') {
        my $mail = sendmail($message);
        print $mail map { s/^~/~~/; "$_\n" } @$headers;
        print $mail "$_\n" . join ('', map { s/^~/~~/; "$_\n" } @$body)
            if $body;
        close $mail or logdie("Cannot send mail: $!");
        return;
    }

    if ($logfile =~ /^([^.\/].*)/) {
        $logfile = $1;
    } else {
        logmsg("Invalid log file: $logfile", 'err');
        $logfile = 'control';
    }

    $logfile = "$inn::most_logs/$logfile.log" unless $logfile =~ /^\//;
    my $lockfile = $logfile;
    $lockfile =~ s#.*/##;
    $lockfile = "$inn::locks/LOCK.$lockfile";
    shlock($lockfile);

    open(LOGFILE, ">>$logfile") or logdie("Cannot open $logfile: $!");
    print LOGFILE "$message\n";
    foreach (@$headers, '', @$body, '') {
        print LOGFILE "    $_\n";
    }
    close LOGFILE;
    unlink $lockfile;
}

# write to syslog or errlog
sub logmsg {
    my ($msg, $lvl) = @_;

    return if $lvl and $lvl eq 'debug' and not $debug;
    if ($use_syslog) {
        syslog($lvl || 'notice', '%s', $msg);
    } else {
        print STDERR (scalar localtime) . ": $msg\n";
    }
}

# log a message and then die
sub logdie {
    my ($msg, $lvl) = @_;

    $msg .= " ($curmsgid)" if $curmsgid;
    logmsg($msg, $lvl || 'err');
    exit 1;
}

# wrappers executing external programs ####################################

# Open an article appropriately to our storage method (or lack thereof).
sub open_article {
    my $token = shift;

    if ($token =~ /^\@.+\@$/) {
        my $pid = open(ART, '-|');
        logdie('Cannot fork: ' . $!) if $pid < 0;
        if ($pid == 0) {
            exec("$inn::newsbin/sm", '-q', $token) or
                logdie("Cannot exec sm: $!");
        }
        return *ART;
    } else {
        return *ART if open(ART, $token);
        logmsg("Cannot open article $token: $!");
    }
    return undef;
}

sub pgpverify {
    my $token = shift;

    if ($token =~ /^\@.+\@$/) {
        open(PGPCHECK, "$inn::newsbin/sm -q $token "
            . "| $inn::newsbin/pgpverify |") or goto ERROR;
    } else {
        open(PGPCHECK, "$inn::newsbin/pgpverify < $token |") or goto ERROR;
    }
    my $pgpresult = <PGPCHECK>;
    close PGPCHECK or goto ERROR;
    $pgpresult ||= '';
    chop $pgpresult;
    return $pgpresult;
ERROR:
    logmsg("pgpverify failed: $!", 'debug');
    return '';
}

sub ctlinnd {
    my ($cmd, @args) = @_;

    my $st = system("$inn::newsbin/ctlinnd", '-s', $cmd, @args);
    logdie('Cannot run ctlinnd: ' . $!) if $st == -1;
    logdie('ctlinnd returned status ' . ($st & 255)) if $st > 0;
}

sub shlock {
    my $lockfile = shift;

    my $locktry = 0;
    while ($locktry < 60) {
        if (system("$inn::newsbin/shlock", '-p', $$, '-f', $lockfile) == 0) {
            return 1;
        }
        $locktry++;
        sleep 2;
    }

    my $lockreason;
    if (open(LOCKFILE, $lockfile)) {
        $lockreason = 'held by ' . (<LOCKFILE> || '?');
        close LOCKFILE;
    } else {
        $lockreason = $!;
    }
    logdie("Cannot get lock $lockfile: $lockreason");
    return undef;
}

# If $body is not defined, returns a file handle which must be closed.
# Don't forget checking the return value of close().
# $addresses may be a scalar or a reference to a list of addresses.
# If not defined, $inn::newsmaster is the default.
# parts of this code stolen from innmail.pl
sub sendmail {
    my ($subject, $addresses, $body) = @_;
    $addresses = [ $addresses || $inn::newsmaster ] if not ref $addresses;
    $subject ||= '(no subject)';

    # fix up all addresses
    my @addrs = map { s#[^-a-zA-Z0-9+_.@%]##g; $_ } @$addresses;

    my $sm = $inn::mta;
    if ($sm =~ /%s/) {
        $sm = sprintf($sm, join(' ', @addrs));
    } else {
        $sm .= ' ' . join(' ', @addrs);
    }

    # fork and spawn the MTA whitout using the shell
    my $pid = open(MTA, '|-');
    logdie('Cannot fork: ' . $!) if $pid < 0;
    if ($pid == 0) {
        exec(split(/\s+/, $sm)) or logdie("Cannot exec $sm: $!");
    }

    print MTA 'To: ' . join(",\n\t", @addrs) . "\nSubject: $subject\n\n";
    return *MTA if not defined $body;
    $body = join("\n", @$body) if ref $body eq 'ARRAY';
    print MTA $body . "\n";
    close MTA or logdie("Execution of $sm failed: $!");
    return 1;
}
