qpsmtpd/qpsmtpd-prefork
Jared Johnson 04f8f7dd98 More robust child spawning for prefork
This should help the prefork daemon to keep up with demand better without using
much more in the way of resources

Signed-off-by: Ask Bjørn Hansen <ask@develooper.com>
2009-09-15 14:39:04 -07:00

750 lines
22 KiB
Perl
Executable File

#!/usr/bin/perl -Tw
# High performance pre-forking qpsmtpd daemon, Copyright (C) 2006 SoftScan
# http://www.softscan.co.uk
#
# Based on qpsmtpd-forkserver Copyright (C) 2001 Ask Bjoern Hansen
# See the LICENSE file for details.
#
# For more information see http://smtpd.develooper.com/
# safety guards
use strict;
BEGIN {
# secure shell
$ENV{'PATH'} = '/bin:/usr/bin';
delete @ENV{qw(IFS CDPATH ENV BASH_ENV)};
}
# includes
use IO::Socket;
use IO::Select;
use POSIX;
use IPC::Shareable(':all');
use lib 'lib';
use Qpsmtpd::TcpServer::Prefork;
use Qpsmtpd::Constants;
use Getopt::Long;
use Config;
defined $Config{sig_name} || die "No signals?";
my $has_ipv6 = Qpsmtpd::TcpServer::has_ipv6;
if ($has_ipv6) {
use Socket6;
}
#use Time::HiRes qw(gettimeofday tv_interval);
#get available signals
my %sig_num;
my $i = 0;
foreach my $sig_name ( split( /\s/, $Config{sig_name} ) )
{
$sig_num{$sig_name} = $i++;
}
# version
my $VERSION = "1.0";
# qpsmtpd instances
my ($qpsmtpd, $qpsmtpd_base);
# cmd's needed by IPC
my $ipcrm = '/usr/bin/ipcrm';
my $ipcs = '/usr/bin/ipcs';
my $xargs = '/usr/bin/xargs';
# vars we need
my $chld_shmem; # shared mem to keep track of children (and their connections)
my %children;
my $chld_pool;
my $chld_busy;
my @children_term; # terminated children, their death pending processing
# by the main loop
my $select = new IO::Select; # socket(s)
# default settings
my $pid_file;
my $d_port = 25;
my @d_addr; # default applied after getopt call
my $debug = 0;
my $max_children = 15; # max number of child processes to spawn
my $idle_children = 5; # number of idle child processes to spawn
my $maxconnip = 10;
my $child_lifetime = 100; # number of times a child may be reused
my $loop_sleep = 15; # seconds main_loop sleeps before checking children
my $re_nice = 5; # substracted from parents current nice level
my $d_start = 0;
my $quiet = 0;
my $status = 0;
my $signal = '';
my $pretty = 0;
my $detach = 0;
my $user;
# help text
sub usage {
print <<"EOT";
Usage: qpsmtpd-prefork [ options ]
--quiet : Be quiet (even errors are suppressed)
--version : Show version information
--debug : Enable debug output
--listen-address addr: Listen for connections on the address 'addr' (either
an IP address or ip:port pair). Listens on all
interfaces by default; may be specified multiple
times.
--port int : TCP port daemon should listen on (default: $d_port)
--max-from-ip int : Limit number of connections from single IP (default: $maxconnip, 0 to disable)
--children int : Max number of children that can be spawned (default: $max_children)
--idle-children int : Number of idle children to spawn (default: $idle_children, 0 to disable)
--pretty-child : Change child process name (default: 0)
--user username : User the daemon should run as
--pid-file path : Path to pid file
--renice-parent int : Subtract value from parent process nice level (default: $re_nice)
--detach : detach from controlling terminal (daemonize)
--help : This message
EOT
exit 0;
}
# get arguments
GetOptions(
'quiet' => \$quiet,
'version' => sub { print "Qpsmtpd Daemon - version $VERSION\n"; exit 0; },
'debug' => \$debug,
'interface|listen-address=s' => \@d_addr,
'port=i' => \$d_port,
'max-from-ip=i' => \$maxconnip,
'children=i' => \$max_children,
'idle-children=i' => \$idle_children,
'pretty-child' => \$pretty,
'user=s' => \$user,
'renice-parent=i' => \$re_nice,
'detach' => \$detach,
'pid-file=s' => \$pid_file,
'help' => \&usage,
) || &usage;
if ($user && $user =~ /^([\w\-]+)$/) { $user = $1 } else { &usage }
if (@d_addr) {
for my $i (0..$#d_addr) {
if ($d_addr[$i] =~ /^(\[.*\]|[\d\w\-.]+)(?::(\d+))?$/) {
$d_addr[$i] = { 'addr' => $1, 'port' => $2 || $d_port };
} else {
print STDERR "Malformed listen address '$d_addr[$i]'\n";
&usage;
}
}
} else {
@d_addr = ( { addr => $has_ipv6 ? "[::]" : "0.0.0.0", port => $d_port } );
}
# set max from ip to max number of children if option is set to disabled
$maxconnip = $max_children if ($maxconnip == 0);
#to fix limit counter error in plugin <hosts_allow>
$maxconnip++;
#ensure that idle_children matches value given to max_children
$idle_children = $max_children
if (!$idle_children || $idle_children > $max_children || $idle_children < -1);
$chld_pool = $idle_children;
if ($pid_file) {
if ($pid_file =~ m#^(/[\w\d/\-.]+)$#) { $pid_file = $1 } else { &usage }
if (-e $pid_file) {
open PID, "+<$pid_file"
or die "open pid_file: $!\n";
my $running_pid = <PID> || ''; chomp $running_pid;
if ($running_pid =~ /(\d+)/) {
$running_pid = $1;
die "Found an already running qpsmtpd with pid $running_pid.\n"
if (kill 0, $running_pid);
}
seek PID, 0, 0
or die "Could not seek back to beginning of $pid_file: $!\n";
truncate PID, 0
or die "Could not truncate $pid_file at 0: $!";
}
else {
open PID, ">$pid_file"
or die "open pid_file: $!\n";
}
}
run();
#start daemon
sub run {
# get UUID/GUID
my ($quid, $qgid, $groups);
if ($user) {
(undef, undef, $quid, $qgid) = getpwnam $user
or die "unable to determine uid/gid for $user\n";
$groups = "$qgid $qgid";
while (my ($name,$passwd,$gid,$members) = getgrent()) {
my @m = split(/ /, $members);
if (grep {$_ eq $user} @m) {
$groups .= " $gid";
}
}
endgrent;
}
for my $addr (@d_addr) {
my @Socket_opts = (
LocalPort => $addr->{port},
LocalAddr => $addr->{addr},
Proto => 'tcp',
Listen => SOMAXCONN,
Reuse => 1,
);
# create new socket (used by clients to communicate with daemon)
my $s;
if ($has_ipv6) {
$s = IO::Socket::INET6->new(@Socket_opts);
}
else {
$s = IO::Socket::INET->new(@Socket_opts);
}
die "FATAL: Failed to open socket on $addr->{addr}:$addr->{port} ($@)"
. "\nIt may be necessary to wait 20 secs before starting daemon"
. " again."
unless $s;
$select->add($s);
}
info("qpsmtpd-prefork daemon, version: $VERSION, staring on host: "
. join(', ', map { "$_->{addr}:$_->{port}"} @d_addr)
. " (user: $user [$<])");
# reset priority
my $old_nice = getpriority(0, 0);
my $new_nice = $old_nice - $re_nice;
if ($new_nice < 20 && $new_nice > -20) {
setpriority(0, 0, $1) if ($new_nice =~ /(\-?\d+)/);
info("parent daemon nice level: $1");
}
else {
die "FATAL: new nice level: $new_nice is not between -19 and 19 "
. "(old level = $old_nice, renice value = $re_nice)";
}
if ($user) {
# change UUID/UGID
$) = $groups;
POSIX::setgid($qgid) or die "unable to change gid: $!\n";
POSIX::setuid($quid) or die "unable to change uid: $!\n";
$> = $quid;
die "FATAL: failed to setuid to user: $user, uid: $quid\n"
if ($> != $quid and $> != ($quid - 2**32));
}
# setup shared memory
$chld_shmem = shmem($d_port."qpsmtpd", 1);
untie $chld_shmem;
# Interrupt handler
$SIG{INT} = $SIG{TERM} = sub {
# terminate daemon (and children)
my $sig = shift;
# prevent another signal and disable reaper
$SIG{$sig} = $SIG{CHLD} = $SIG{HUP} = 'IGNORE';
# a notice, before the sleep below
info("shutting down");
# close socket(s)
$_->close for $select->handles;
# send signal to process group
kill -$sig_num{$sig} => $$;
# cleanup
IPC::Shareable->clean_up;
unlink($pid_file) if $pid_file;
info("shutdown of daemon");
exit;
};
# Hup handler
$SIG{HUP} = sub {
# reload qpmstpd plugins
$qpsmtpd = $qpsmtpd_base = qpsmtpd_instance('restart' => 1); # reload plugins...
$qpsmtpd->load_plugins;
kill 'HUP' => keys %children;
info("reload daemon requested");
};
# setup qpsmtpd_instance(s), _base is for resetting to a known state
# after each connection
$qpsmtpd = $qpsmtpd_base = qpsmtpd_instance();
if ($detach) {
open STDIN, '/dev/null' or die "/dev/null: $!";
open STDOUT, '>/dev/null' or die "/dev/null: $!";
open STDERR, '>&STDOUT' or die "open(stderr): $!";
defined (my $pid = fork) or die "fork: $!";
exit 0 if $pid;
}
POSIX::setsid or die "setsid: $!";
if ($pid_file) {
print PID $$,"\n";
close PID;
}
# child reaper
$SIG{CHLD} = \&reaper;
spawn_children();
main_loop();
exit;
}
# initialize children (only done at daemon startup)
sub spawn_children {
# block signals while new children are being spawned
my $sigset = block_signal(SIGCHLD);
for (1 .. $chld_pool) {
new_child();
}
# reset block signals
unblock_signal($sigset);
}
# cleanup after child dies
sub reaper {
my $stiff;
while (($stiff = waitpid(-1, &WNOHANG)) > 0) {
my $res = WEXITSTATUS($?);
info("child terminated, pid: $stiff (status $?, res: $res)");
delete $children{$stiff}; # delete pid from children
# add pid to array so it later can be removed from shared memory
push @children_term, $stiff;
}
$SIG{CHLD} = \&reaper;
}
#main_loop: main loop. Either processes children that have exited or
# periodically scans the shared memory for children that are not longer
# alive. Spawns new children when necessary.
#arg0: void
#ret0: void
sub main_loop {
my $created_children = $idle_children;
while (1) {
# if there is no child death to process, then sleep EXPR seconds
# or until signal (i.e. child death) is received
sleep $loop_sleep / ($created_children * 2 + 1) unless @children_term;
# block CHLD signals to avoid race
my $sigset = block_signal(SIGCHLD);
# get number of busy children
if (@children_term) {
# remove dead children info from shared memory
$chld_busy = shmem_opt(undef, \@children_term, undef, undef);
@children_term = ();
}
else {
# just check the shared memory
$chld_busy = shmem_opt(undef, undef, undef, undef, 1);
}
# calculate children in pool (if valid busy children number)
if (defined($chld_busy)) {
info("busy children: $chld_busy");
$chld_pool = $chld_busy + $idle_children;
# ensure pool limit is max_children
$chld_pool = $max_children if ($chld_pool > $max_children);
info( "children pool: $chld_pool, spawned: "
. scalar(keys %children)
. ", busy: $chld_busy");
}
else {
# reset shared memory
warn("unable to access shared memory - resetting it");
IPC::Shareable->clean_up;
my $shmem = shmem($d_port . "qpsmtpd", 1);
untie $shmem;
}
# spawn children
$created_children = $chld_pool - keys %children;
$created_children = 0 if $created_children < 0;
new_child() for 1..$created_children;
# unblock signals
unblock_signal($sigset);
}
}
# block_signal: block signals
# arg0..n: int with signal(s) to block
# ret0: ref str with sigset (used to later unblock signal)
sub block_signal {
my @signal = @_; #arg0..n
my ($sigset, $blockset);
$sigset = POSIX::SigSet->new();
$blockset = POSIX::SigSet->new(@signal);
sigprocmask(SIG_BLOCK, $blockset, $sigset)
or die "Could not block @signal signals: $!\n";
return ($sigset);
}
# unblock_signal: unblock/reset and receive pending signals
# arg0: ref str with sigset
# ret0: void
sub unblock_signal {
my $sigset = shift; # arg0
sigprocmask(SIG_SETMASK, $sigset)
or die "Could not restore signals: $!\n";
}
# new_child: initialize new child
# arg0: void
# ret0: void
sub new_child {
# daemonize away from the parent process
my $pid;
die "Cannot fork child: $!\n" unless defined($pid = fork);
if ($pid) {
# in parent
$children{$pid} = 1;
info("new child, pid: $pid");
return;
}
# in child
# reset priority
setpriority 0, 0, getpriority(0, 0) + $re_nice;
# reset signals
my $sigset = POSIX::SigSet->new();
my $blockset = POSIX::SigSet->new(SIGCHLD);
sigprocmask(SIG_UNBLOCK, $blockset, $sigset)
or die "Could not unblock SIGCHLD signal: $!\n";
$SIG{CHLD} = $SIG{INT} = $SIG{TERM} = $SIG{ALRM} = 'DEFAULT';
# child should exit if it receives HUP signal (note: blocked while child
# is busy, but restored once done)
$SIG{HUP} = sub {
info("signal HUP received, going to exit");
exit;
};
# continue to accept connections until "old age" is reached
for (my $i = 0 ; $i < $child_lifetime ; $i++) {
# accept a connection
if ( $pretty ) {
$ENV{PROCESS} = $0 if not defined $ENV{PROCESS}; # 1st time only
$0 = 'qpsmtpd child'; # set pretty child name in process listing
}
my @ready = $select->can_read();
next unless @ready;
my $socket = $ready[0];
my ($client, $iinfo) = $socket->accept()
or die
"failed to create new object - $!"; # wait here until client connects
info("connect from: " . $client->peerhost . ":" . $client->peerport);
# clear a previously running instance by cloning the base:
$qpsmtpd = $qpsmtpd_base;
# set STDIN/STDOUT and autoflush
# ... no longer use POSIX::dup2: it failes after a few
# million connections
close(STDIN);
open(STDIN, "+<&".fileno($client))
or die "unable to duplicate filehandle to STDIN - $!";
close(STDOUT);
open(STDOUT, "+>&".fileno($client))
or die "unable to duplicate filehandle to STDOUT - $!";
select(STDOUT);
$| = 1;
# connection recieved, block signals
my $sigset = block_signal(SIGHUP);
# start a session if connection looks valid
qpsmtpd_session($socket, $client, $iinfo, $qpsmtpd) if ($iinfo);
# close connection and cleanup
$client->shutdown(2);
# unset block and receive pending signals
unblock_signal($sigset);
}
exit; # this child has reached its end-of-life
}
# respond to client
# arg0: ref to socket object (client)
# arg1: int with SMTP reply code
# arg2: arr with message
# ret0: int 0|1 (0 = failure, 1 = success)
sub respond_client {
my ($client, $code, @message) = @_;
$client->autoflush(1);
while (my $msg = shift @message) {
my $line = $code . (@message ? "-" : " ") . $msg;
info("reply to client: <$line>");
print $client "$line\r\n"
or (info("Could not print [$line]: $!"), return 0);
}
return 1;
}
# qpsmtpd_instance: setup qpsmtpd instance
# arg0: void
# ret0: ref to qpsmtpd_instance
sub qpsmtpd_instance {
my %args = @_;
my $qpsmtpd = Qpsmtpd::TcpServer::Prefork->new(%args);
$qpsmtpd->load_plugins;
$qpsmtpd->spool_dir;
$qpsmtpd->size_threshold;
return ($qpsmtpd);
}
# shmem: tie to shared memory hash
# arg0: str with glue
# arg1: int 0|1 (0 = don't create shmem, 1 = create shmem)
# ret0: ref to shared hash
sub shmem {
my $glue = shift; #arg0
my $create = shift || 0; #arg1
my %options = (
create => $create,
exclusive => 0,
mode => 0640,
destroy => 0,
);
my %shmem_hash;
eval {
tie %shmem_hash, 'IPC::Shareable', $glue, {%options}
|| die "unable to tie to shared memory - $!";
};
if ($@) {
info("$@");
return;
}
return (\%shmem_hash);
}
# shmem_opt: connect to shared memory and perform options
# arg0: ref to hash where shared memory should be copied to
# arg1: ref to arr with pid(s) to delete
# arg2: int with pid to add (key)
# arg3: str with packed iaddr to add (value)
# arg4: int 0|1 check and cleanup shared memory (0 = no, 1 = yes - default 0)
# ret0: int with number of busy children (undef if error)
sub shmem_opt {
my $ref_shmem = shift; #arg0
my $ref_pid_del = shift; #arg1
my $pid_add_key = shift; #arg2
my $pid_add_value = shift; #arg3
my $check = shift || 0; #arg4
# check arguments
if ( (defined($pid_add_key) && !defined($pid_add_value))
|| (!defined($pid_add_key) && defined($pid_add_value)))
{
return;
}
my ($chld_shmem, $chld_busy);
eval {
$chld_shmem = &shmem($d_port."qpsmtpd", 0); #connect to shared memory hash
if (tied %{$chld_shmem}) {
# lock shared memory
eval {
# ensure that hung shared memory is noticed
local $SIG{ALRM} = sub {
die "locking timed out\n";
};
alarm 15;
(tied %{$chld_shmem})->shlock(LOCK_EX);
alarm 0;
};
die $@ if $@;
# delete
if ($ref_pid_del) {
foreach my $pid_del (@{$ref_pid_del}) {
delete $$chld_shmem{$pid_del};
}
}
# add
$$chld_shmem{$pid_add_key} = $pid_add_value if ($pid_add_key);
# copy
%{$ref_shmem} = %{$chld_shmem} if ($ref_shmem);
# check
if ($check) {
# loop through pid list and delete orphaned processes
foreach my $pid (keys %{$chld_shmem}) {
if (!kill 0, $pid) {
delete $$chld_shmem{$pid};
warn("orphaned child, pid: $pid removed from memory");
}
}
}
# number of busy children
$chld_busy = scalar(keys %{$chld_shmem});
# unlock shared memory
(tied %{$chld_shmem})->shunlock;
# untie from shared memory
untie $chld_shmem || die "unable to untie from shared memory";
}
else {
die "failed to connect to shared memory";
}
};
# check for error
if ($@) {
undef($chld_busy);
warn("$@");
}
return ($chld_busy);
}
# info: write info
# arg0: str with debug text
sub info {
my $text = shift; #arg0
return if (!$debug);
my ($sec, $min, $hour, $mday, $mon, $year) = localtime(time);
my $nowtime = sprintf "%02d/%02d/%02d %02d:%02d:%02d", $mday, $mon + 1,
$year + 1900, $hour, $min, $sec;
chomp($text);
print STDERR "$nowtime:$$: $text\n";
}
# start qpmstpd session
# arg0: ref to socket object
# arg1: ref to socket object
# arg2: ref to qpsmtpd instance
# ret0: void
sub qpsmtpd_session {
my $socket = shift; #arg0
my $client = shift; #arg1
my $iinfo = shift; #arg2
my $qpsmtpd = shift; #arg3
# get local/remote hostname, port and ip address
my ($port, $iaddr, $lport, $laddr, $nto_iaddr, $nto_laddr) =
Qpsmtpd::TcpServer::lrpip($socket, $client, $iinfo);
# get current connected ip addresses (from shared memory)
my %children;
shmem_opt(\%children, undef, $$, $iaddr);
my ($rc, @msg) =
$qpsmtpd->run_hooks(
"pre-connection",
remote_ip => $nto_iaddr,
remote_port => $port,
local_ip => $nto_laddr,
local_port => $lport,
max_conn_ip => $maxconnip,
child_addrs => [values %children],
);
if ( $rc == DENYSOFT
|| $rc == DENYSOFT_DISCONNECT
|| $rc == DENY
|| $rc == DENY_DISCONNECT)
{
#smtp return code to reply client with (seed with soft deny)
my $rc_reply = 451;
unless ($msg[0]) {
if ($rc == DENYSOFT || $rc == DENYSOFT_DISCONNECT) {
@msg = ("Sorry, try again later");
}
else {
@msg = ("Sorry, service not available to you");
$rc_reply = 550;
}
}
respond_client($client, $rc_reply, @msg);
# remove pid from shared memory
shmem_opt(undef, [$$], undef, undef);
# retur so child can be reused
return;
}
# all children should have different seeds, to prevent conflicts
srand(time ^ ($$ + ($$ << 15)));
# ALRM handler
$SIG{ALRM} = sub {
print $client "421 Connection Timed Out\n";
info("Connection Timed Out");
# child terminates
exit;
};
# set enviroment variables
($ENV{TCPLOCALIP}, $ENV{TCPREMOTEIP}, $ENV{TCPREMOTEHOST}) = Qpsmtpd::TcpServer::tcpenv($nto_laddr, $nto_iaddr);
# run qpmsptd functions
$SIG{__DIE__} = 'DEFAULT';
eval {
$qpsmtpd->start_connection(
local_ip => $ENV{TCPLOCALIP},
local_port => $lport,
remote_ip => $ENV{TCPREMOTEIP},
remote_port => $client->peerport,
);
$qpsmtpd->run($client);
$qpsmtpd->run_hooks("post-connection");
$qpsmtpd->connection->reset;
};
if ($@ !~ /^(disconnect_tcpserver|died while reading from STDIN)/) {
warn("$@");
}
# child is now idle again
info("disconnect from: $nto_iaddr:$port");
# remove pid from shared memory
unless (defined(shmem_opt(undef, [$$], undef, undef))) {
# exit because parent is down or shared memory is corrupted
info("parent seems to be down, going to exit");
exit 1;
}
}