CODEWITHSUNDEEP
phpsqldatetimecompare
Mark Segal
Mark Segal

Reputation: 5550

Compare times in PHP as string

I need a method that gets two strings that represents a DateTime (in the MySql syntax) and returns the time difference between them.
Then I need to compare that time to 3 seconds so I could block a Brute Force attack on my server.

I've messed a lot with Google and I managed to get the string representation of the DateTime object, but I can't manage to convert and compare them.

Upvotes: 0

Views: 675

Answers (5)

Lawrence Cherone
Lawrence Cherone

Reputation: 46602

Heres an alternative method using a session, no need to query a db for a timestamp:

<?php 
session_start();

function post_check($limit){
    //Check for first time
    if(isset($_SESSION['post_check'])){
        //Check for count on failed 
        if(isset($_SESSION['post_check_count'])){
            //If fail count is more then 3 block till user closes down browser
            if($_SESSION['post_check_count']>$limit){
                die('Too many requsets to the server, please close down your browesr and try again.');
            }
        }else{
             //Set for count on failed
            $_SESSION['post_check_count']=0;
        }

        //Check (time-limit) against timestamp held in session
        if(($_SESSION['post_check']+$limit)<=time()){
            //Update timestamp
            $_SESSION['post_check']=time();
            //Ok
            return true;
        }else{
            //Update Fail count
            $_SESSION['post_check_count']++;
            //Fail
            return false;
        }
    }else{
        //Set for first time
        $_SESSION['post_check']=time();
        return true;
    }
}


//Pretty self explanitry here
if(post_check('3')===true){
    echo 'Allowed: handle post stuff here';
}else{
    echo'Too many requests within given time limit do nothing';
}
?>

Upvotes: 1

Shef
Shef

Reputation: 45589

$time_str1 = '2011-09-10 19:59:23'; // first string datetime from DB
$time_str2 = '2011-09-10 19:59:24'; // second string datetime from DB

// first DateTime object created based on the MySQL datetime format
$dt1 = DateTime::createFromFormat('Y-m-d H:i:s', $time_str1);

// second DateTime object created based on the MySQL datetime format
$dt2 = DateTime::createFromFormat('Y-m-d H:i:s', $time_str2);

// difference comparison to check if at least 3 seconds have passed
if ( ($dt2->format('U') - $dt1->format('U')) > 3) {
    echo 'Ok, no brute force'; // yes, three seconds have passed
} else{
    echo 'We got you newbie'; // nope, three second haven't passed
}

Upvotes: 2

Dave Lasley
Dave Lasley

Reputation: 6252

strtotime( $timeStr ) which will convert to the amount of seconds since epoch http://en.wikipedia.org/wiki/Unix_epoch . Then you can just use standard mathematical operators. Be warned, strtotime can be inaccurate sometimes. To convert back, date("m-d-Y H:i:s", $time)

Upvotes: 1

KingCrunch
KingCrunch

Reputation: 131891

$diffInSeconds = $dateTimeLater->format('U') - $dateTimeFirst->format('U');

Upvotes: 1

Philippe Plantier
Philippe Plantier

Reputation: 8073

On the MySQL side:

SELECT UNIX_TIMESTAMP(my_time) FROM my_table

On the PHP side, you then have UNIX timestamps in seconds, which you can compare.

Upvotes: -1

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