PHP/MySQL poll - no repeat voting based on IP - php

Question

I have a php/mysql poll that I'm trying to modify.
It sets a unique cookie if you've voted and blocks you from voting twice on the same poll if the cookie is set. If it set then you can only see the results.
What I would like to do is block the user from voting more than once if their IP is in the database as well (I know sessions would be better but not possible for my situation).
I've managed to grab the IP and store it in the db but I can't figure out the logic to tell the poll if it's in the database or not.
Can someone point me in the right direction?
The cookie detection is in the constructor and vote methods. The cookie is set at the end of the vote method.
<?php
# don't display errors
ini_set('display_errors',0);
error_reporting(E_ALL|E_STRICT);
class webPoll {
# makes some things more readable later
const POLL = true;
const VOTES = false;
# number of pixels for 1% on display bars
public $scale = 2;
public $question = '';
public $answers = array();
private $header = '<form class="webPoll" method="post" action="%src%">
<input type="hidden" name="QID" value="%qid%"/>
<h4>%question%</h4>
<fieldset><ul>';
private $center = '';
private $footer = "\n</ul></fieldset>%button%\n%totalvotes%\n</form>\n";
private $button = '<p class="buttons"><button type="submit" class="vote">Vote!</button></p>';
private $totalvotes = '';
private $md5 = '';
private $id = '';
/**
* ---
* Takes an array containing the question and list of answers as an
* argument. Creates the HTML for either the poll or the results depending
* on if the user has already voted
*/
public function __construct($params) {
$this->id = array_shift($params);
$this->question = array_shift($params);
$this->answers = $params;
$this->md5 = md5($this->id);
$this->header = str_replace('%src%', $_SERVER['SCRIPT_NAME'], $this->header);
$this->header = str_replace('%qid%', $this->md5, $this->header);
$this->header = str_replace('%question%', $this->question, $this->header);
# seperate cookie for each individual poll (has the user voted yet?)
# if cookie is set then show results(VOTES), if not then let user vote(POLL)
isset($_COOKIE[$this->md5]) ? $this->poll(self::VOTES) : $this->poll(self::POLL);
}
private function poll($show_poll) {
$replace_btn = $show_poll ? $this->button : '';
$get_results = webPoll::getData($this->md5);
$total_votes = array_sum($get_results);
$replace_votes = $show_poll ? $this->totalvotes : '<small>Total Votes: '.$total_votes.'</small>';
$this->footer = str_replace('%button%', $replace_btn, $this->footer);
$this->footer = str_replace('%totalvotes%', $replace_votes, $this->footer);
# static function doesn't have access to instance variable
if(!$show_poll) {
$results = webPoll::getData($this->md5);
$votes = array_sum($results);
}
for( $x=0; $x<count($this->answers); $x++ ) {
$this->center .= $show_poll ? $this->pollLine($x) : $this->voteLine($this->answers[$x],$results[$x],$votes);
}
echo $this->header, $this->center, $this->footer;
}
private function pollLine($x) {
isset($this->answers[$x+1]) ? $class = 'bordered' : $class = '';
return "
<li class='$class'>
<label class='poll_active'>
<input type='radio' name='AID' value='$x' />
{$this->answers[$x]}
</label>
</li>
";
}
private function voteLine($answer,$result,$votes) {
$result = isset($result) ? $result : 0;
$percent = round(($result/$votes)*100);
$width = $percent * $this->scale;
return "
<li>
<div class='result' style='width:{$width}px;'> </div>{$percent}%
<label class='poll_results'>
$answer
</label>
</li>
";
}
/**
* processes incoming votes. votes are identified in the database by a combination
* of the question's MD5 hash, and the answer # ( an int 0 or greater ).
*/
static function vote() {
if(!isset($_POST['QID']) || !isset($_POST['AID']) || isset($_COOKIE[$_POST['QID']])) {
# leave vote method if any of the above are true
return;
}
$dbh = new PDO('mysql:host=????;dbname=????', '????', '');
$dbh->setAttribute( PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION );
try {
# add vote info to 'tally' table
$sth = $dbh->prepare("INSERT INTO tally (QID,AID,votes,created_at) values (?, ?, 1, NOW())");
$ex = array($_POST['QID'],$_POST['AID']);
$sth->execute($ex);
# add ip info to 'ips' table
$sth2 = $dbh->prepare("INSERT INTO ips (ips,QID,AID) values (?,?,?)");
$ex2 = array($_SERVER['REMOTE_ADDR'],$_POST['QID'],$_POST['AID']);
$sth2->execute($ex2);
}
catch(PDOException $e) {
# 23000 error code means the key already exists, so UPDATE!
if($e->getCode() == 23000) {
try {
# update number of votes for answers in 'tally' table
$sth = $dbh->prepare("UPDATE tally SET votes = votes+1 WHERE QID=? AND AID=?");
$sth->execute(array($_POST['QID'],$_POST['AID']));
# add ip info to 'ips' table
$sth2 = $dbh->prepare("INSERT INTO ips (ips,QID,AID) values (?,?,?)");
$ex2 = array($_SERVER['REMOTE_ADDR'],$_POST['QID'],$_POST['AID']);
$sth2->execute($ex2);
}
catch(PDOException $e) {
webPoll::db_error($e->getMessage());
}
}
else {
webPoll::db_error($e->getMessage());
}
}
# entry in $_COOKIE to signify the user has voted, if he has
if($sth->rowCount() == 1) {
setcookie($_POST['QID'], 1, time()+60*60*24*365, '/', '', FALSE, TRUE);
$_COOKIE[$_POST['QID']] = 1;
}
}
static function getData($question_id) {
try {
$dbh = new PDO('mysql:host=????;dbname=????', '????', '');
$dbh->setAttribute( PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION );
$STH = $dbh->prepare('SELECT AID, votes FROM tally WHERE QID = ?');
$STH->execute(array($question_id));
}
catch(PDOException $e) {
# Error getting data, just send empty data set
return array(0);
}
while($row = $STH->fetch()) {
$results[$row['AID']] = $row['votes'];
}
return $results;
}
/*
* You can do something with the error message if you like. Email yourself
* so you know something happened, or make an entry in a log
*/
static function db_error($error) {
echo "A database error has occurred. $error";
exit;
}
}
?>
And here's how the poll is implemented:
<?php
ini_set('display_errors',1);
error_reporting(E_ALL|E_STRICT);
include('webPoll-hiddenMD5.class.php');
webPoll::vote();
?>
<html>
<head>
<title>Poll Test</title>
<link rel="stylesheet" href="poll.css" type="text/css" />
<!--[if IE]>
<style> body { behavior: url("res/hover.htc"); } </style>
<![endif]-->
</head>
<body>
<?php
$a1 = new webPoll(array(
'March 16, 2012 What subjects would you like to learn more about?',
'What subjects would you like to learn more about?',
'HTML & CSS',
'Javascript',
'JS Frameworks (Jquery, etc)',
'Ruby/Ruby on Rails',
'PHP',
'mySQL'));
?>
</body>
</html>

Answer 1

Looks as if all your logic is in the constructor, simply do a query against the ip table for the users ip and qid and see if the number of results is greater then 0. If so then just change the last line of the constructor isset($_COOKIE[$this->md5] || count($res)>0 ) ? $this->poll(self::VOTES) : $this->poll(self::POLL);