state_machine

#!/usr/bin/perl

#### -------------------- LANGUAGE DIRECTIVES -------------------

use strict;
use feature "switch";


#### -------------------- IMPORT DEPENDENCIES -------------------

use Fcntl qw(:DEFAULT :flock :seek :Fcompat);
use Sys::Syslog qw(:standard :macros);


#### -------------------- INITIALIZE VARIABLES -------------------

our $state_file      = "/var/netbuster.state";
our $state_fh        = undef;
our $state_contents  = undef;
our $log_destination = 3;  # 1 - stdout, 2 - syslog, 3 - both
our $log_is_open     = 0;
our $log_identity    = "netbuster";


#### -------------------- MAIN -------------------

&state_lock;
if ($ARGV[0] eq "startup") {
	&handle_startup;
}
&state_unlock;

exit 0;



#### -------------------- HANDLING ACTIONS -------------------

sub handle_startup {
	my $cmd = "./handle_startup wlan1 /etc/wpa_supplicant/wpa_supplicant.conf";
	&execute_cmd($cmd);
}


#### -------------------- UTILITY FUNCTIONS -------------------

sub execute_cmd {
	my($cmd) = @_;
	log_print(LOG_INFO, "Executing: $cmd");
	open FIN, "$cmd 2>&1|" or die "Can't run command ($cmd): $!";
	while(<FIN>) {
		chomp;
		log_print(LOG_INFO, "--> $_");
	}
	close FIN;
}


#### -------------------- LOGGING FUNCTIONS -------------------

sub log_print {
	my($level, $string) = @_;
	if ($log_destination & 2) {
		if (!$log_is_open) {
			openlog($log_identity, 'pid,ndelay', LOG_USER);
			$log_is_open = 1;
		}
		syslog($level, '%s', $string);
	}
	if ($log_destination & 1) {
		print "$string\n";
	}
}


#### -------------------- STATE FILE FUNCTIONS -------------------

# Gains an exclusive lock to the state file
#   - blocks until lock is obtained
#   - prevents multiple runs of this script from clobbering each other
# Reads contents of state file into a state variable.
sub state_lock {
	#open $state_fh, '+>', $state_file or die "Couldn't open $state_file: $!";
	sysopen($state_fh, $state_file, O_RDWR | O_CREAT) or die "Could not open $state_file: $!";
	$state_fh->autoflush(1);
	flock($state_fh, LOCK_EX) or die "Could not lock file $state_file: $!";
	$state_contents = <$state_fh> || "";
	&log_print(LOG_INFO, "starting with state '$state_contents'");
}

# Writes the new state variable to the state file.
# Closes/Unlocks the state file.
sub state_unlock {
	seek($state_fh, 0, SEEK_SET) or die "Could not seek $state_file: $!";
	&log_print(LOG_INFO, "ending with state '$state_contents'");
	print $state_fh $state_contents;
	truncate($state_fh, tell($state_fh)) or die "Could not truncate $state_file: $!";
	close $state_fh or die "Could not close lock file $state_file: $!";
}