#!/usr/bin/perl
# Run scripts that do network stuff for intermittent 802.11 connections

# configuration
$if = 'eth0';
$timeout = 6;
$queue = '/var/spool/burst';

# programs
$ifconfig = '/sbin/ifconfig';
$iwconfig = '/usr/sbin/iwconfig';
$iwgetid = '/usr/sbin/iwgetid';
$dhcpcd = '/sbin/dhcpcd';

sub process_queue {
	@children = ();
	opendir QUEUE, $queue;
	@jobs = grep {/^[^.]/} readdir(QUEUE);
	closedir(QUEUE);
	print "forking ";
	foreach $job (@jobs) {
		print "$job ";
		$x = fork();
		if ($x) {
			push(@children,$x);
		} else {
			exec("$queue/$job");
			print "exec failed: $?\n";
			exit(1);
		}
	}
	print "\n";
	print "Waiting for all children to complete...\n";
	foreach $child (@children) {
		waitpid $child, 0;
		print "$child exited\n";
	}
}

sub ifreset {
	system("$ifconfig $if down");
	sleep(1);
	system("$ifconfig $if up");
}

# Reset the interface.
&ifreset;
# Wait for an ESSID to show up
while (1) {
	$cell = (split(/ +/,`$iwgetid --ap $if`))[3];
	chomp $cell;
	next if ($cell eq $prevcell);
	if ($cell ne '00:00:00:00:00:00') {
		# Got a live one...
		`$iwgetid $if` =~ /ESSID:"(.*)"/;
		$essid = $1;
		print "Found $essid - $cell. Attempting DHCP...\n";
		# Lock in the essid
		system("$iwconfig $if essid $essid");
		$n = system("$dhcpcd -t $timeout $if");
		$exit = $n >> 8;
		if ($exit == 0) {	# success! process the queue!
			$ENV{'ESSID'} = $essid;
			$ENV{'CELL'} = $cell;
			&process_queue;
			delete $ENV{'ESSID'};
			delete $ENV{'CELL'};
			print "Done.\n";
		} else {
			print "DHCP failed.\n";
			&ifreset;
		}
	} else {
		# Lost connection. Shut it down.
		system("killall dhcpcd");
		&ifreset;
	}
	# unlock essid
	system("$iwconfig $if essid any");
	$prevcell = $cell;
	sleep(1);
}