#!/usr/bin/perl -w
#
# freeside-selfservice-clientd
#
# This is run REMOTELY over ssh by freeside-selfservice-server

use strict;
use subs qw(spawn logmsg lock_write unlock_write);
use Fcntl qw(:flock);
use POSIX qw(:sys_wait_h);
use Socket;
use Storable 2.09 qw(nstore_fd fd_retrieve);
use IO::Handle qw(_IONBF);
use IO::Select;
use IO::File;

#STDOUT->setbuf('');

my $tag = scalar(@ARGV) ? '.'.shift : '';

use vars qw( $Debug );
$Debug = 2; #2 will turn on child logging, 3 will log packet contents,
            #including potentially compromising information

my $socket = "/usr/local/freeside/selfservice_socket$tag";
my $pid_file = "$socket.pid";

my $log_file = "/usr/local/freeside/selfservice$tag.log";

my $lock_file = "/usr/local/freeside/selfservice$tag.writelock";

#my $me = '[client]';

$|=1;

$SIG{__WARN__} = \&_logmsg;

#read data to be cached or something
#warn "$me Reading init data\n" if $Debug;
#my $signup_init = 

warn "Creating $lock_file\n" if $Debug;
open(LOCKFILE,">$lock_file") or die "can't open $lock_file: $!";

warn "Creating $socket\n" if $Debug;
my $uaddr = sockaddr_un($socket);
my $proto = getprotobyname('tcp');
socket(Server,PF_UNIX,SOCK_STREAM,0) or die "socket: $!";
unlink($socket);
bind(Server, $uaddr) or die "bind: $!";
listen(Server,SOMAXCONN) or die "listen: $!";

if ( -e $pid_file ) {
  open(PIDFILE,"<$pid_file");
  my $old_pid = <PIDFILE>;
  close PIDFILE;
  $old_pid =~ /^(\d+)$/;
  kill 'TERM', $1;
}
open(PIDFILE,">$pid_file");
print PIDFILE "$$\n";
close PIDFILE;

#my $waitedpid;
#sub REAPER { $waitedpid = wait; $SIG{CHLD} = \&REAPER; }
#$SIG{CHLD} =  \&REAPER;

warn "entering main loop\n" if $Debug;

my %kids;

my $s = new IO::Select;
$s->add(\*STDIN);
$s->add(\*Server);

#for ( $waitedpid = 0;
#      accept(Client,Server) || $waitedpid;
#      $waitedpid = 0, close Client)
#{
#  next if $waitedpid;

#$SIG{PIPE} = sub { warn "SIGPIPE received" };
#$SIG{CHLD} = sub { warn "SIGCHLD received" };

#sub REAPER { warn "SIGCHLD received"; my $pid = wait; $SIG{CHLD} = \&REAPER; }
#sub REAPER { my $pid = wait; $SIG{CHLD} = \&REAPER; }
#sub REAPER { my $pid = wait; delete $kids{$pid}; $SIG{CHLD} = \&REAPER; }
#$SIG{CHLD} =  \&REAPER;

my $undisp = 0;
while (1) {

  &reap_kids;

  warn "waiting for connection\n" if $Debug && !$undisp;

  #my @handles = $s->can_read();
  my @handles = $s->can_read(5);
  $undisp = !scalar(@handles);
  foreach my $handle ( @handles ) {

    if ( $handle == \*STDIN ) {

      warn "receiving packet from server\n" if $Debug;

      my $packet = fd_retrieve(\*STDIN);
      my $token = $packet->{'_token'};
      warn "received packet from server with token $token\n".
           ( $Debug > 2
             ? join('', map { " $_=>$packet->{$_}\n" } keys %$packet )
             : '' )
        if $Debug;

     if ( exists($kids{$token}) ) {
        warn "sending return packet to $token via $kids{$token}\n"
          if $Debug;
        nstore_fd($packet, $kids{$token});
        warn "flushing to $token\n" if $Debug;
        until ( $kids{$token}->flush ) {
          warn "WARNING: error flushing: $!";
          sleep 1;
        }
        #no close or delete here - will block waiting for child
        warn "done with $token\n" if $Debug;
      } else {
        warn "WARNING: unknown token $token, discarding message";
      }

    } elsif ( $handle == \*Server ) {

      until ( accept(Client, Server) ) {
        warn "WARNING: accept failed: $!";
        next;
      }

      warn "received local connection; forking\n" if $Debug;

      spawn sub { #child
        warn "[child-$$] reading packet from local client" if $Debug > 1;
        my $packet = fd_retrieve(\*Client);
        warn "[child-$$] packet received:\n".
             join('', map { " $_=>$packet->{$_}\n" } keys %$packet )
          if $Debug > 2;
        my $command = $packet->{'command'};
        #handle some commands weirdly?
        $packet->{_token}=$$;

        warn "[child-$$] locking write stream\n" if $Debug > 1;
        lock_write;

        warn "[child-$$] sending packet to remote server\n" if $Debug > 1;
        nstore_fd($packet, \*STDOUT) or die "FATAL: can't send response: $!";
        
        warn "[child-$$] flushing write stream\n" if $Debug > 1;
        STDOUT->flush or die "FATAL: can't flush: $!";
        
        warn "[child-$$] releasing write lock\n" if $Debug > 1;
        unlock_write;

        warn "[child-$$] closing write stream\n" if $Debug > 1;
        close STDOUT or die "FATAL: can't close write stream: $!"; #??!

        warn "[child-$$] waiting for response from parent\n" if $Debug > 1;
        my $w = new IO::Select;
        $w->add(\*STDIN);
        until ( $w->can_read ) {
          warn "[child-$$] WARNING: interrupted select: $!\n";
        }
        my $rv = fd_retrieve(\*STDIN);

        #close STDIN;

        warn "[child-$$] sending response to local client" if $Debug > 1;
        nstore_fd($rv, \*Client);
        Client->flush or die "FATAL: can't flush to local client: $!";
        close Client or die "FATAL: can't close connection to local client: $!";

        warn "[child-$$] child exiting" if $Debug > 1;
        exit;

      }; #eo child

      #close Client;

    } else {
      die "wtf?  $handle";
    }

  }
  
}

sub reap_kids {
  #warn "reaping kids\n";
  foreach my $pid ( keys %kids ) {
    my $kid = waitpid($pid, WNOHANG);
    if ( $kid > 0 ) {
      close $kids{$kid};
      delete $kids{$kid};
    }
  }
  #warn "done reaping\n";
}

sub spawn {
    my $coderef = shift;

    unless (@_ == 0 && $coderef && ref($coderef) eq 'CODE') {
        use Carp;
        confess "usage: spawn CODEREF";
    }

    my $pid;
    #if (!defined($pid = fork)) {
    my $kid = new IO::Handle;
    if (!defined($pid = open($kid, '|-'))) {
        warn "WARNING: cannot fork: $!";
        return;
    } elsif ($pid) {
        warn "begat $pid" if $Debug;
        $kids{$pid} = $kid;
        #$kids{$pid}->autoflush;
        return; # I'm the parent
    }
    # else I'm the child -- go spawn

#    open(STDIN,  "<&Client")   || die "can't dup client to stdin";
#    open(STDOUT, ">&Client")   || die "can't dup client to stdout";
#     open(STDERR, ">&STDOUT") || die "can't dup stdout to stderr";
    exit &$coderef();
}

sub _logmsg {
  chomp( my $msg = shift );
  my $log = new IO::File ">>$log_file";
  die "can't open $log_file: $!" unless defined($log);
  flock($log, LOCK_EX);
  seek($log, 0, 2);
  print $log "[client] [". scalar(localtime). "] [$$] $msg\n";
  flock($log, LOCK_UN);
  close $log;
}

sub lock_write {
  #broken on freebsd?
  #flock(STDOUT, LOCK_EX) or die "FATAL: can't lock write stream: $!";

  flock(LOCKFILE, LOCK_EX) or die "FATAL: can't lock $lock_file: $!";
}

sub unlock_write {
  #broken on freebsd?
  #flock(STDOUT, LOCK_UN) or die "FATAL: can't release write lock: $!";

  flock(LOCKFILE, LOCK_UN) or die "FATAL: can't unlock $lock_file: $!";
}