#!/usr/bin/perl -w
#
# Prochosts.pl downloads a new hosts file, and searches it for entries not in the old one
# it adds what it finds to the bottom of a new hosts file and distributes it to all machines 
# in a local network (including local machine). It also allows local overrides of bad and good sites.
# Tested using ActivePerl 5.8 on WinXP.  
#
# # the optional manualhosts.txt file consists of
# # 1) A line with "OK" (no quotes) followed by more than 0 lines with 
# # URLs (www.xxx.yyy) which are permitted even if they are blocked by
# # the hosts file
# #
# # 2) A line with "BLOCK" (no quotes) followed by more than 0 lines
# # with URLs (www.xxx.yyy) which will be blocked even if they do not
# # appear in the hosts file
# # 
# # 3) (optional) blank lines or comments.  Comments have a # in column 1
# 
# Note: The folder in which this script is run needs a \old subfolder or script will fail. 
#
# By Jeff Winston  http://www.kwcpa.com/tools  tools@kwcpa.com
# Rev. 1.0,  11/16/09 Copyright (C) 2009
# Rev. 1.1,  12/ 6/09 Copyright (C) 2009 Bug fixes
# Rev. 1.2,   1/21/10 Copyright (C) 2010 Bug fixes
#
# ---------------------------------------------------------------------
# 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 2
# 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.  or check out http://www.gnu.org/copyleft/gpl.html
# ---------------------------------------------------------------------
#
use LWP::simple;
$|=1;
$debug=0;

# host file destinations
# add other machines to list by using the format:
#  "\\\\<othermachine>\\<system drive>\\windows\\system32\\drivers\\etc\\hosts"
@locations = ("c:\\windows\\system32\\drivers\\etc\\hosts");


# figure out the date, we'll need it
($day, $month, $year) = (localtime)[3,4,5];
$month = $month + 1;
$year = $year - 100;
$date = sprintf "%02s_%02s_%02s",$month,$day,$year;

# URL, filenames
$hosts_url  = "http://mvps.org/winhelp2002/hosts.txt";
$master     = "masterhosts.txt";  # existing hosts file
$hostfile   = "hosts.txt";        # raw new hostfile
$manhosts   = "manualhosts.txt";  # manual additions to host file (see top of this script for format)
$new_output = "HOSTS_" . $date;   # logged copy of new hosts file

# get the hosts file from the mvps site
if ($debug == 0) {
    print "Getting a new hosts file...";
    unless(@content = LWP::Simple::get($hosts_url)) { die "Failed to get hosts file at $hosts_url";}
    open (HFIL," > $hostfile") or die "Failed to open $hostfile";
    foreach $line (@content) {print HFIL $line;}
    print "written\n";
}
close (HFIL);

%blocksites=();
$cnt=0;
@mas_lines=();

# read in the current file, build a hash of all existing blocked websites
if (-e $master) {
    open (MFILE,  "< $master") or die "error opening $master\n";
    while (defined ($line = <MFILE>)) {
	$cnt++;
	chomp $line;
	
	# get rid of ^M at end of line
	while (substr($line,-1,1) eq "\r") {
	    $line = substr($line,0,-1);
	}
	
	$dup=0;
	if ((substr($line,0,1) ne "\#") && (length($line) > 10)) {
	    @tokens = split " ",$line;
	    if ($tokens[0] eq "127.0.0.1") {
		if ($#tokens == 0) {
		    print "$master: Bad line $cnt $line\n";
		} else {
		    if (exists($blocksites{$tokens[1]})) {
			$dup=1;
		    } else {
			$blocksites{$tokens[1]} = 0;
		    }
		}
	    }
	}
	# don't print lines that are duplicates
	if ($dup == 0) {
	    push @mas_lines, $line;
	}
    }
    close (MFILE);
}
# read in manual specification file if one exists
if (-e $manhosts) {
    open (OFILE,  "< $manhosts")  or die "error opening $manhosts\n";
    $ok=0;
    while (defined ($line = <OFILE>)) {
	chomp $line;
	# get rid of ^M at end of line
	while (substr($line,-1,1) eq "\r") {
	    $line = substr($line,0,-1);
	}
	if ((substr($line,0,1) ne "\#") && (length($line) > 1)) {
	    if ($line =~ "OK") {
		$ok = 1;
	    }
	    elsif ($line =~ "BLOCK") {
		$ok = 0;
	    } else {
		@tokens = split " ",$line;
		if ($ok == 1) {
		    push @goodsites, $tokens[0];
		} else {
		    #only add bad sites not in original file
		    if (!(exists($blocksites{$tokens[0]}))) {
			push @badsites, $tokens[0];
			$blocksites{$tokens[0]} = 1;
		    }
		}
	    }
	}
    }
    close (OFILE);
}

$cnt=0;
# read in the new file, build a list of all websites not in the current list
open (HFIL, "< $hostfile") or die "Failed to open $hostfile";

while(defined($line=<HFIL>)) {
    $cnt++;
    if ((substr($line,0,1) ne "\#") && (length($line) > 10)) {
	chomp $line;
	# get rid of ^M at end of line
	while (substr($line,-1,1) eq "\r") {
	    $line = substr($line,0,-1);
	}
	@tokens = split " ",$line;
	if ($tokens[0] eq "127.0.0.1") {
	    if ($#tokens == 0) {
		print "$hostfile: Bad line $cnt $line\n";
	    } else {
		# only add bad sites not in original file
		if (!(exists($blocksites{$tokens[1]}))) {
		    $blocksites{$tokens[1]} = 1;
		    push @newlines, "$line\n";
		}
	    }
	}
    }
}
close (HFIL);

# skim both master and new lists and remove matches to good list
foreach $line (@mas_lines) {
    $ok=1;
    foreach $site (@goodsites) {
	if ($line =~ $site) {
	    $ok=0;
	    last;
	}
    }
    if ($ok == 1) {
	push @mas_lines2, $line;
    }
}

foreach $line (@newlines) {
    $ok=1;
    foreach $site (@goodsites) {
	if ($line =~ $site) {
	    $ok=0;
	    last;
	}
    }
    if ($ok == 1) {
	push @newlines2, $line;
    }
}

# open the output file
open (OUTFIL, "> $new_output")  or die "error opening $new_output\n";
# init
print OUTFIL "# Generated by PROCHOSTS.PL on $date\n";

# print the sites from the original file
foreach $line (@mas_lines2) {
    print OUTFIL "$line\n";
}

# and the new sites
if ($#newlines2 > -1) {
    print OUTFIL "\n# Sites added $date\n";
    foreach $line (@newlines2) {
	print OUTFIL $line;
    }
}
# and the extra sites
$head=0;
foreach $line (@badsites) {
    if ($head == 0) {
	print OUTFIL "\n# Sites explicitly added $date\n";
	$head=1;
    }
    print OUTFIL "127.0.0.1  $line\n";
    print "127.0.0.1  $line\n";
}

#we're done
close (OUTFIL);

if ($debug == 1) {exit;}

# update files
if (-e $master) {
    `del $master`;
}
if (!(-e "old")) {
    print "Attempting to create subdir \"old\"...\n";
    system("mkdir old");
}
`copy $new_output old\\$new_output`;
`move $new_output $master`;

# distribute host files
foreach $loc (@locations) {
    print "updating $loc\n";	
    `attrib -r -s -h $loc`;
    `copy $master $loc`;
    `attrib +r +s +h $loc`;
}
system("pause");