#!/usr/bin/perl -w

$seq = 0;

sub tempfile
{
  my $file;
  do
  {
    $file = sprintf "/tmp/perlexec%d", ++$seq;
  }
  while(-e $file);
  return $file
}

sub execute
{
  my $file = tempfile();
  open(EX, "> $file") or die;
  print EX "@_";
  close(EX);
  my $rc = system "sh $file";
  unlink $file;
  return $rc;
}
            
sub branch
{
  my $file = "/tmp/perlexec";
  open(EX, "> $file") or die;
  print EX "@_\n";
  close(EX);
  exec "sh $file";
}
            
$| = 1;
$ssid = shift;
$iface = "wlan0";

if(defined $ssid and $ssid eq "-h")
{
  print "usage: connect [ssid]\n";
  print "if no ssid is provided you will be given a choice of available AP's\n";
  exit;
}

# do a site survey if ssid not given

if(not defined $ssid)
{
  print "scanning...";
  unlink "/tmp/wscan";
  execute "wscan -i $iface -a -b -o -n 5 > /dev/null";
  print "\n\n";
  
  execute "cd /tmp; mv wscan wscan.tmp; sort -rn wscan.tmp > wscan; rm wscan.tmp";
  open(FILE, "/tmp/wscan") or die "wscan failed\n";
  while(defined ($line = <FILE>))
  {
    next if $line =~ /^\s*$/;
    push @list, $line;
  }
  close(FILE);
  
  die "no open access points found\n" if not @list;
  
  print "    Sig Rel Ch E              SSID                     MAC      Vendor\n";
  print "    --- --- -- - -------------------------------- ------------- ------\n";
  for($i = 0; $i < @list; ++$i)
  {
    printf "%2d: %s", $i + 1, $list[$i];
  }
  print "\n";
  
  while(1)
  {
    print "which access point [1] ? ";
    $ans = <STDIN>;
    die "connect aborted\n" if not defined $ans;
    chomp $ans;
    $ans = "1" if $ans eq "";
    next if $ans !~ /^\d+$/;
    next if $ans < 1 or $ans > @list;
    last;
  }
  
  $ssid = substr $list[$ans - 1], 13, 32;
  $ssid =~ s/\s+$//;
}

# associate

print "associating with $ssid ";

for($i = $done = 0; $i < 30 and not $done; ++$i)
{
  print ".";
  system "iwconfig $iface mode managed";
  execute "iwconfig $iface essid '$ssid'";
  sleep 1;
  execute "iwconfig $iface | grep -q 'ESSID:\"$ssid\"'";
  sleep 1;
  execute "iwconfig $iface | grep -q 'Not-Associated'";
  $done = 1 if $?;
}

print "\n";
die "association failed\n" if not $done;

# get a dhcp lease

print "requesting a dhcp lease\n";
execute "kill `cat /var/run/dhcp-wlan0.pid` 2>/dev/null" if -e "/var/run/dhcp-wlan0.pid";

$pid = fork;

if(!$pid)
{
  branch "udhcpc -t 0 -i $iface -b -p /var/run/dhcp-wlan0.pid -R 2>/dev/null";
}

# check for an address

for($i = $done = 0; $i < 60 and not $done; ++$i)
{
  sleep 1;
  execute "ifconfig $iface | grep -q 'inet addr'";
  $done = 1 if not $?;
}

if(not $done)
{
  execute "kill `cat /var/run/dhcp-wlan0.pid` 2>/dev/null" if -e "/var/run/dhcp-wlan0.pid";
  die "dhcp failed\n";
}

sleep 2;
print "connection successful\n";
exit 0;