challenges/newbiecontest/prog/2nd_degre/2nd_degre.pl

#!/usr/bin/env perl

# uses #########################################################################
use diagnostics;
use warnings;
use strict;
# Modules
# database
use DBI;
# http
use LWP::UserAgent;
use HTTP::Cookies;

# subs #########################################################################
# extract cookie from SQLite db
sub extract_cookie
{
    # shift db_path
    my $db_path = shift;

    # variables usefull for database connection and handler
    my $dbh;
    my $sth;
    my $rv;
    my @row;

    # string containing the query
    my $query;

    # connect to the db
    $dbh = DBI->connect("dbi:SQLite:dbname=$db_path","","") or die $DBI::errstr;

    # prepare the query
    $query = "SELECT name, value FROM moz_cookies WHERE host LIKE\
    '%newbiecontest.org%' AND name LIKE '%SMFCookie%'";
    $sth = $dbh->prepare($query);

    # execute
    $rv = $sth->execute() or die $DBI::errstr;

    # fetch the only row found
    @row = $sth->fetchrow_array();

    # close the database
    $sth->finish();
    $dbh->disconnect();

    return $row[0], $row[1];

}

# Send http request
sub send_request
{

    # shift args
    my ($cookie_name, $cookie_val, $url) = @_;

    # create variables
    my $ua = LWP::UserAgent->new;
    my $cookies = HTTP::Cookies->new();

    # create the cookie
    $cookies->set_cookie(0, $cookie_name, $cookie_val, '/', 'newbiecontest.org', 80, 0, 0,\
        0, 0);

    # add the cookie to the jar
    $ua->cookie_jar($cookies);

    # send request
    my $response = $ua->get($url);

    return $response->decoded_content;

}

# solve equation
sub solve_equation
{
    # shift equation
    my $equation = shift;

    # variables
    my $delta;
    my $x1;
    my $x2;
    my $sol;
    my $sol_trunc;

    print("\n" . $equation . "\n");

    # calcul delta
    ($delta, $a, $b) = delta($equation);

    # if it's < 0, no solution
    if ($delta < 0) {
        print("\t There is no solution...\n");
        exit;
    }

    # if delta == 0
    if ($delta == 0) {
        $sol = - $b / (2 * $a);
    }

    # else (delta > 0), 2 solutions
    else {
        # calcul x1 and x2
        $x1 = - ($b - sqrt($delta)) / (2 * $a);
        $x2 = - ($b + sqrt($delta)) / (2 * $a);

        # determine the one who is valid for the answer of the challenge
        if ($x1 > $x2) {
            $sol = $x1;
        }

        else {
            $sol = $x2;
        }
    }

    # truncate (2 decimals)
    $sol_trunc = (int ($sol * 100));
    $sol_trunc /= 100;

    # return the solution
    return $sol_trunc;

}

# calcul delta
sub delta
{
    # variables
    my $delta;
    my $a;
    my $b;
    my $c;

    # shift the equation
    my $equation = shift;

    # funny time
    print("\t Regex time boy !\n");

     # regex
    $equation =~ m/(\d*)x. (.) (\d*)x (.) (\d*)/;

    print("\t Regex time is done ! Well done\n");

    # reorder all the coefficients
    $a = $1;

    if ($a eq "") {
        $a = 1;
    }

    $b = $3;

    if ($3 eq "") {
        $b = 1;
    }

    if ($2 eq "-") {
        $b *= -1;
    }

    $c = $5;

    if ($c eq "") {
        $c = 0;
    }

    if ($4 eq "-") {
        $c *= -1;
    }

    # calcul delta
    $delta = $b * $b - 4 * $a * $c;

    # return needed values
    return $delta, $a, $b;

}

# send answer
sub send_answer
{
    my ($cookie_name, $cookie_val, $url, $result) = @_;

    # create variables
    my $ua = LWP::UserAgent->new;
    my $cookies = HTTP::Cookies->new();

    # modify the url
    $url = $url . "?solution=" . $result;

    # create the cookie
    $cookies->set_cookie(0, $cookie_name, $cookie_val, '/', 'newbiecontest.org', 80, 0, 0,\
        0, 0);

    # add the cookie to the jar
    $ua->cookie_jar($cookies);

    # send request
    my $response = $ua->get($url);

    print $response->decoded_content;
}

# main #########################################################################
# check argument number
if (@ARGV != 3) {

    print("Get. The. Fuck. Out\n");
    print("[i] Usage : ./2nd_degre.pl cookie.db url_in url_out\n");

    exit;
}

my $cookie_name;
my $cookie_val;
my $equation;
my $result;

($cookie_name, $cookie_val) = extract_cookie($ARGV[0]);

$equation = send_request($cookie_name, $cookie_val, $ARGV[1]);

$result = solve_equation($equation);

send_answer($cookie_name, $cookie_val, $ARGV[2], $result);

print("Done.\n");