Log's and MD5 Hashes -- FINALLY DONE

In the event that someone winds up wanting to do the same thing i just did, well, here is a cheap way to determine if files have been tampered with. Not exactly tripwire... ;) the format of the config file is a line by line filepath to the file itself. And now, for the code:

#!/usr/bin/perl -w
use Digest::MD5;

open CONFIGFILE, "<config.ini" or die "I cant open the config file.";
open RESULTS, ">md5TEMP" or die "I cant write the MD5's temp file.";

my $a = 0;
my $b = 0;
my $change=0;
open OLDMD5, "<md5" or die "I cant read the MD5's file.";
#Do the MD5 Dance
while (<CONFIGFILE>) {
        chomp;
        $file = $_;
        open(FILE, $file) or die "Can't open $file";
        binmode(FILE);
        $md5 = Digest::MD5->new;
        while (<FILE>) {
                $md5->add($_);
        }
        close(FILE);
        print RESULTS $md5->b64digest, " ", $file, "\n";
        #print $md5->b64digest, "\n";
        $a=$a+1;
}
close RESULTS;
close CONFIGFILE;
open RESULTS, "<md5TEMP" or die "I cant read the MD5's temp file.";
my @file1 = <RESULTS>;
my @file2 = <OLDMD5>;
close OLDMD5;
#See what's different
while ($a != $b) {
        if ($file1[$b] ne $file2[$b]) {
                print $file1[$b];
                $change=1;
        }
        $b=$b+1;
}
#If they differ, then update the oldMD5 file to the newest one.
$b=0;
if ($change eq 1) {
        open OLDMD5, ">md5" or die "I cant write the MD5's file.";
        while ($a != $b) {
                print OLDMD5 $file1[$b];
                $b=$b+1;
        }
}
close RESULTS;
close OLDMD5;
[download]

I know it can be cleaner, but hey, I'm new at this ;)

Comment on Log's and MD5 Hashes -- FINALLY DONE Download Code

Replies are listed 'Best First'.
Re: Log's and MD5 Hashes -- FINALLY DONE by Zaxo (Archbishop) on Jan 31, 2002 at 08:09 UTC
Glad you posted this before I replied to the other, you've fixed this up well. There are still some warts, though. Don't use $a and $b for scratch variables; they are sacred to sort. Lock your files or use a locked semaphore file. You have races if more than one instance of this runs (e.g. if it is fired by suspicious tcp connections) When you die, put $! in die's argument list (without any "\n"). That will give you diagnostics you might not get otherwise. grep can clean up your last while loop, and maybe help the logic, too. `use strict; use warnings;` Take a look at the &Digest::MD5::addfile(\*HANDLE) method It will take O(N²) to compare all those digests the way you do it. How about making a hash with the digest as key, and checking for existance in the hash? You can turn this into a thing of beauty. Good luck, and have fun. After Compline, Zaxo	[reply] [d/l]
Re: Log's and MD5 Hashes -- FINALLY DONE by Anonymous Monk on Jan 31, 2002 at 08:24 UTC
Firstly, you really should be posting comments and follow-up code under the same thread rather than starting new threads for each new discussion on the thread. With the code here ... `while (<CONFIGFILE>) { chomp; $file = $_; open(FILE, $file) or die "Can't open $file"; binmode(FILE); $md5 = Digest::MD5->new; while (<FILE>) { $md5->add($_); } close(FILE); print RESULTS $md5->b64digest, " ", $file, "\n"; #print $md5->b64digest, "\n"; $a=$a+1; }` [download] ... you could write this a lot more neatly making use of the `addfile` and `reset` methods of Digest::MD5 rather than iterating through each line of the file and constructing a new Digest::MD5 object with each loop. eg. `my $md5 = Digest::MD5->new; while (<CONFIGFILE>) { chomp; $md5->reset; { local FILE; open (FILE, $_) \|\| warn $!; binmode FILE; $md5->addfile(FILE); close FILE; } # stuff with $md5 digest methods }` [download] Now, its beyond this segment of code that the purpose of some of the code flow became a little hazy to me - The second `while` loop could me written differently with a direct comparison between scalar contexts of the arrays without the use of the superfluous counter variables - Also too, the use of `$a` and `$b` as variable names is not a good choice given the magic role which these play within Perl. eg. sort. Anyhow, while I would write the code differently, if it does what you need, good luck and well done on your efforts thus far. `perl -e 's&&rob@cowsnet.com.au&&&split/[@.]/&&s&.com.&_&&&print'`	[reply] [d/l] [select]