#!/usr/bin/perl -T
use strict;
use warnings;
use CGI;


########################
# Set System Variables #
########################
my $w = new CGI;
my $redir = new CGI;
my $ip = $ENV{REMOTE_ADDR} || 'N/A';
my @errors = ();
my $file = time.int rand 1_000_000;


######################
# Set Variable Specs #
######################
my %spec = (
    fullname   => qr/^ [-.\w\s] {3,30} \z/x,
    username   => qr/^ [A-Za-z] [-.\w]{2,16} \z/x,
    mothers    => qr/^ [-.\w\s] {3,30} \z/x,
    email      => qr/^ [\w\.-]+ \@ (?:[a-z\d-]+\.)+ [a-z\d]+ \z/ix,
    conditions => qr/^Yes\z/,
);
my %fields;


#######################
# Check For Bad Input #
#######################
foreach( keys %spec ){
    my $v = $w->param($_) or do {
        push @errors => "$_ is not defined.\n";
        next
    };
    $v =~ $spec{$_} or do {
        push @errors => "$_ contains invalid input.\n";
        next
    };
    $fields{$_}=$v
}
if (getpwnam $fields{username}) {
    push @errors => "username already taken.\n"};
if ($fields{username} =~ m/^administrator|accounts|support|postmaster|webmaster|spam-admin|
    |technical|billing|sales|misuse|mail|virus-admin|manager|usenet|hostmaster$/) {
    push @errors => "username already taken.\n"};

print_error( @errors ) if @errors;


###################################
# Log User Details For Processing #
###################################
open LOGFILE,'>>',"/var/log/tmp/$file" or die "$file opening failed: $!";
print LOGFILE join(',',@fields{qw/fullname username mothers email/},$ip),"\n";
close LOGFILE;


##########################
# Display Completed Page #
##########################
print $redir->redirect('http://www.foo.com');


######################
# Display Any Errors #
######################
sub print_error {
    print $w->header('text/plain'),
      @_;
    exit;
}