afraid-dyndns Rev2

#!/usr/bin/perl

#
#   afraid-dyndns - a Dynamic DNS client for the afraid.org free service
#   Copyright (C) 2009 Erick Calder
#   Copyright (C) 2011 platnicat mewr
#
#   This program is free software; you can redistribute it and/or modify
#   it under the terms of the GNU General Public License as published by
#   the Free Software Foundation; either version 3 of the License, or
#   (at your option) any later version.
#
#   This program is distributed in the hope that it will be useful,
#   but WITHOUT ANY WARRANTY; without even the implied warranty of
#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#   GNU General Public License for more details.
#
#   You should have received a copy of the GNU General Public License
#   along with this program; if not, write to the Free Software
#   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
#

$|++;
$\ = $/;

use LWP::Simple;
use XML::Simple;
# use Data::Dumper;
use Getopt::Long;

Getopt::Long::Configure("no_ignore_case");
$args{"quiet"} = "Suppresses normal output";
$args{"help"} = "Display syntax";
GetOptions(\%ARGV, keys %args);

if ($ARGV{help}) {
    echo("Syntax: $0 [--quiet] [--help] [hostname]");
    echo("    quiet: supresses all output");
    echo("    help: displays syntax");
    echo("    hostname: indicates that only the specified name should be refreshed");
    exit;
    }

# afraid.org listing of urls

$afraid = "http://freedns.afraid.org/api/?action=getdyndns&sha=%s&style=xml";
($VER = substr $Revision: 2 $, 10) =~ s/\s+$//;
$CACHEDIR = "/var/cache/afraid-dyndns/IP"; # set cache directory
$HASH = "<your_hash>"; # account hash for authentication
($ME = $0) =~ s|.*/||;
$hostname = shift;

echo("Original script by Erick Calder, this fork by platnicat mewr");
echo("-- $0 (Ver: $VER) --");
echo("License: GPL");

#
# get external and cached IP addresses
#


$extip = get("http://automation.whatismyip.com/n09230945.asp"); # Fetch current IP from whatismyip
die "Failed to get IP" unless $extip; # If IP wasn't acquired, go poof
$intip = readfile($CACHEDIR);   # internal address (cached)
chomp $intip;

echo("Read $intip as cached IP, $extip is the new one, if applicable");

#
# when these differ modify the DNS and cache the address
#

if ($extip eq $intip) {   # check if the new IP and the current IP are the same
    echo("No change in address!");
} else {
    echo("Address changed: $intip => $extip");

    $xml = get(sprintf($afraid, $HASH));
    die "Failed fetching update head!" unless $xml;
    $o = XMLin($xml);
    writefile($CACHEDIR, $extip);
    }

exit;

#
#   Syntax:
#       readfile [file-name = $_]
#       <scalar> = readfile [file-name = $_]
#       <list> = readfile [file-name = $_]
#   Synopsis:
#       returns the contents of a given file.  if called in a void
#       context, this function sets $_; if called in a scalar context
#       the contents are returned as a single string with embedded
#       newlines; and if called in a list context the content comes
#       back as separate lines.
#

sub readfile {
    my $f = shift || $_;
    local $_ if defined wantarray();
    -f $f || return;
    open(F, $f) || warn($!) && return;
    wantarray() && (@_ = <F>) || (local $/ = undef, $_ = <F>);
    close(F);
    wantarray() ? @_ : $_;
    }

#
#   Syntax:
#       writefile <file-name> [content = $_]
#   Synopsis:
#       writes a string to a file, returns success/failure
#

sub writefile($@) {
    my $fn = shift;
    local $_ = shift || $_ || return;

    print ">> writefile(): $fn" if $::DEBUG;

    mkpath(path2fn($fn));
    open(OUT, "> $fn") || warn(qq|writefile("> $fn"): "$!"|) && return;
    print OUT;
    close(OUT) || return;
    return 1;
    }

#
#   could've used system("mkdir -p") but
#   that won't work on Win32 systems
#

sub mkpath {
    local $_ = shift;
    my @d = split m(/);
    my $d = "";
    my $mkpath = 0;

    for (@d) {
        $d .= "$_/";
        next if -d $d;  # skip if it already exists
        print "- $d" if $::DEBUG > 1;
        mkdir($d) || warn(qq/mkdir("$d"): "$!"/) && return;
        $mkpath = 1;
        }

    return 1;
    }

#
#   splits a path into directory, filename and extension
#   e.g. ($dir, $fn, $ext) = path2fn($path)
#

sub path2fn {
    my $path = shift;
    my ($dir, $fn, $ext);

    @x = split(/\//, $path);
    $fn = pop @x;
    $dir = join("/", @x);
    @x = split(/\./, $fn);
    if (@x > 1) {
        $ext = pop @x;
        $fn = join(".", @x);
        }

    return ($dir, $fn, $ext);
    }

#
#   output functions
#

sub debug {
    print shift if $ARGV{debug} && !$ARGV{quiet};
    }

sub echo {
    print shift || $_ unless $ARGV{quiet};
    }