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PHP Spam Prevention

Please carry me as I am a graphic designer with some coding knowledge, but not as close as the developer. And after many hours of messing around and asking Google, I decided to ask y'all directly!

I am working on creating a contact form for my site. So far, all is well, except for one. I would like to add a simple field to prevent spam.

I added a "spamcheck" field with question 6 + 2 =? but I don’t know how to encode PHP to require the value to be 8. As long as the other fields are correctly filled out, the form will be sent regardless of the number entered here, despite any attempt to spoil the code (this way why you see my spamcheck variable, but the current encoding only requires that it has a value similar to the rest of the fields).

I have included PHP, the validation that PHP is accessing, and the form. Sorry if the form has redundant code; I tried many different versions of the PHP form tutorials to no avail.

And, of course, many thanks for your help! :)

Here is the PHP code that I posted directly on the web page:

<?php 
define("EMAIL", "email@gmail.com");

if(isset($_POST['submit'])) {

  include('validate.class.php');

  //assign post data to variables 
    $name = trim($_POST['name']);
    $email = trim($_POST['email']);
    $budget = trim($_POST['budget']);
    $deadline = trim($_POST['deadline']);
    $message = trim($_POST['message']);
    $spamcheck = trim($_POST['spamcheck']);

  //start validating our form
  $v = new validate();
  $v->validateStr($name, "name", 1, 50);
  $v->validateEmail($email, "email");
  $v->validateStr($budget, "budget");
  $v->validateStr($deadline, "deadline");
  $v->validateStr($message, "message", 1, 1000);
  $v->validateStr($spamcheck, "spamcheck");

  if(!$v->hasErrors()) {
       $from = "website.com"; //Site name
  // Change this to your email address you want to form sent to
  $to = "email@gmail.com"; 
  $subject = "Hello! Comment from " . $name . "";

  $message = "Message from " . $name . "
  Email: " . $email . " 
  Budget: " . $budget ."
  Deadline: " . $deadline ."
  Message: " . $message ."";
  mail($to,$subject,$message,$from);


    //grab the current url, append ?sent=yes to it and then redirect to that url
        $url = "http". ((!empty($_SERVER['HTTPS'])) ? "s" : "") . "://".$_SERVER['SERVER_NAME'].$_SERVER['REQUEST_URI'];
        header('Location: '.$url."?sent=yes");

    } else {
    //set the number of errors message
    $message_text = $v->errorNumMessage();       

    //store the errors list in a variable
    $errors = $v->displayErrors();

    //get the individual error messages
    $nameErr = $v->getError("name");
    $emailErr = $v->getError("email");
    $budgetErr = $v->getError("budget");
    $deadlineErr = $v->getError("deadline");
    $messageErr = $v->getError("message");
    $spamcheckErr = $v->getError("spamcheck");

  }//end error check
}// end isset
  ?>

This is validate.class.php, which it calls:

<?php
class validate {

  public $errors = array();

   public function validateStr($postVal, $postName, $min = 1, $max = 1000) {
    if(strlen($postVal) < intval($min)) {
      $this->setError($postName, ucfirst($postName)." is required.");
    } else if(strlen($postVal) > intval($max)) {
      $this->setError($postName, ucfirst($postName)." must be less than {$max} characters long.");
    }
  }// end validateStr

   public function validateEmail($emailVal, $emailName) {
    if(strlen($emailVal) <= 0) {
      $this->setError($emailName, "Please enter an Email Address");
    } else if (!preg_match('/^[^0-9][a-zA-Z0-9_]+([.][a-zA-Z0-9_]+)*[@][a-zA-Z0-9_]+([.][a-zA-Z0-9_]+)*[.][a-zA-Z]{2,4}$/', $emailVal)) {
      $this->setError($emailName, "Please enter a Valid Email Address");
        }
  }// end validateEmail     

  private function setError($element, $message) {
    $this->errors[$element] = $message;
  }// end logError


  public function getError($elementName) {
    if($this->errors[$elementName]) {
      return $this->errors[$elementName];
    } else {
      return false;
    }
  }// end getError

  public function displayErrors() {
    $errorsList = "<ul class=\"errors\">\n";
    foreach($this->errors as $value) {
      $errorsList .= "<li>". $value . "</li>\n";
    }
    $errorsList .= "</ul>\n";
    return $errorsList;
  }// end displayErrors

  public function hasErrors() {
    if(count($this->errors) > 0) {
      return true;
    } else {
      return false;
    }
  }// end hasErrors

  public function errorNumMessage() {
    if(count($this->errors) > 1) {
            $message = "There was an error sending your message!\n";
        } else {
            $message = "There was an error sending your message!\n";
        }
    return $message;
  }// end hasErrors

}// end class
?>

And here is the html / php form:

<span class="message"><?php echo $message_text; ?></span>
   <?php if(isset($_GET['sent'])): ?><h2>Your message has been sent</h2><?php endif; ?>
          <form role="form" method="post" action="webpage.php#contact">
            <div class="form-group">
              <input type="text" name="name" class="form-control" id="name" value="<?php echo htmlentities($name); ?>" placeholder="Full Name" required>
              <label for="exampleInputName"><i class="icon-tag"></i></label>
              <span class="errors"><?php echo $nameErr; ?></span>
              <div class="clearfix"></div>
            </div>
            <div class="form-group">
              <input type="email" name="email" class="form-control" id="email" value="<?php echo htmlentities($email); ?>" placeholder="Email" required>
              <label for="exampleInputEmail1"><i class="icon-inbox"></i></label>
              <span class="errors"><?php echo $emailErr; ?></span>
              <div class="clearfix"></div>
            </div>
            <div class="form-group">
              <input type="text" name="budget" class="form-control" id="budget" value="<?php echo htmlentities($budget); ?>" placeholder="Budget" required>
              <label for="exampleInputBudget1"><i class="icon-usd"></i></label>
              <span class="errors"><?php echo $budgetErr; ?></span>
              <div class="clearfix"></div>
            </div>
            <div class="form-group">
              <input type="text" name="deadline" class="form-control" id="deadline" value="<?php echo htmlentities($deadline); ?>" placeholder="Deadline" required>
              <label for="exampleInputDeadline"><i class="icon-calendar"></i></label>
              <span class="errors"><?php echo $deadlineErr; ?></span>
              <div class="clearfix"></div>
            </div>
            <div class="form-group textarea">
              <textarea rows="6" name="message" class="form-control" id="message" value="<?php echo htmlentities($message); ?>" placeholder="Write Message" required></textarea>
              <label for="exampleInputMessage"><i class="icon-pencil"></i></label>
              <span class="errors"><?php echo $messageErr; ?></span>
              <div class="clearfix"></div>
            </div>
            <div class="form-group">
              <input type="text" name="spamcheck" class="form-control" id="spamcheck" value="<?php echo htmlentities($spamcheck); ?>" placeholder="Spam check: 6+2=?" required>
              <label for="exampleInputSpamCheck"><i class="icon-lock"></i></label>
              <span class="errors"><?php echo $spamcheckErr; ?></span>
              <div class="clearfix"></div>
            </div>

            <button type="submit" id="submit" name="submit" value="submit" class="btn btn-large">Send Message</button>
          </form>
+4
2

captcha. . , "fakeField". validateSTR .

$v->validateStr($fakeField, "fakeField",0,0);

str > < >= <= true, 0. , .

, , , , .

:

public function validateCaptcha( $value,$name, $expectedValue) {
if(trim($value) != $expectedValue) {
  $this->setError($name, "Captcha Incorrect");
    }
}


$v->validateStr($spamcheck, "spamcheck");


$v->validateCaptcha($spamcheck, "spamcheck", '6');

, captchas, .

+1

PHP script, , $_SESSION.

PHP script, , , , , $_SESSION.

, PHP.

, :

form.php

<?php
    session_start();
    $_SESSION['captcha_right_answer'] = somehow_generate_this();
?>

handler.php

<?php
    session_start();

    if ($_INPUT['captcha_answer'] != $_SESSION['captcha_right_answer']) {
        // Show "bad captcha" message, re-show form, whatever
    }
    else {
        // Captcha good - go on with life
    }
?>
+3

Source: https://habr.com/ru/post/1531891/

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