title: Paypal IPN Donations
body: <p>I have a wordpress 1 page site that has an option to download a music track after a paypal donation - with a minimum amount of $3.99.</p>
  
  <p>the button works fine and the paypal payment goes through - but I'm only getting INVALID back from paypal - it doesnt seem to be writing back the content to paypal correctly.</p>
  
  <p>Also - How can I see what paypal is posting back to me?</p>
  
  <p>Any help is greatly appreciated!</p>
  
  <p><strong>inside the included php file:</strong></p>
  
  <pre><code>&lt;?php echo "&lt;p class='small-donate'&gt;Minimum ammount for donation is $3.99&lt;/p&gt;
  &lt;form method='POST' action=''  target='_top'&gt;
  $&lt;input type='text' name='donate_amount' value='0' size='4' class='donate-input'&gt;
  &lt;input type='submit' name='submit' value='Donate' class='donate-submit'&gt;&lt;/form&gt;";
  if(!empty($_POST['submit'])) {
  // Form has been submitted
    if($_POST['donate_amount'] &gt;= 3.99) {
  // Redirect to PayPal
  $myurl = site_url();
  $fileurl = site_url('wp-content/themes/MY_THEME/content-download-file.php');
  header('Location: https://www.sandbox.paypal.com/cgi-bin/webscr?cmd=_donations&amp;item_name=Donation for music track&amp;amount='.$_POST['donate_amount'].'&amp;currency_code=USD&amp;business=MY_SANDBOX_TEST_EMAIL&amp;cbt=Download the file&amp;return='.$fileurl.'&amp;cancel_return='.$myurl);
  }
  else {
  echo '&lt;span class="error"&gt;Donation must be at least $3.99&lt;/span&gt;';
  }
  }
  ?&gt; 
  </code></pre>
  
  <p><strong>inside content-download-file.php</strong></p>
  
  <p>(I got this from paypal developers)</p>
  
  <pre><code>&lt;?php
  // STEP 1: read POST data
  
  // Reading POSTed data directly from $_POST causes serialization issues with array data in the POST.
  // Instead, read raw POST data from the input stream. 
  $raw_post_data = file_get_contents('php://input');
  $raw_post_array = explode('&amp;', $raw_post_data);
  $myPost = array();
  foreach ($raw_post_array as $keyval) {
    $keyval = explode ('=', $keyval);
    if (count($keyval) == 2)
       $myPost[$keyval[0]] = urldecode($keyval[1]);
  }
  // read the IPN message sent from PayPal and prepend 'cmd=_notify-validate'
  $req = 'cmd=_notify-validate';
  if(function_exists('get_magic_quotes_gpc')) {
     $get_magic_quotes_exists = true;
  } 
  foreach ($myPost as $key =&gt; $value) {        
     if($get_magic_quotes_exists == true &amp;&amp; get_magic_quotes_gpc() == 1) { 
          $value = urlencode(stripslashes($value)); 
     } else {
          $value = urlencode($value);
     }
     $req .= "&amp;$key=$value";
  }
  
  
  // Step 2: POST IPN data back to PayPal to validate
  
  $ch = curl_init('https://www.sandbox.paypal.com/cgi-bin/webscr');
  curl_setopt($ch, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_1_1);
  curl_setopt($ch, CURLOPT_POST, 1);
  curl_setopt($ch, CURLOPT_RETURNTRANSFER,1);
  curl_setopt($ch, CURLOPT_POSTFIELDS, $req);
  curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, 1);
  curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 2);
  curl_setopt($ch, CURLOPT_FORBID_REUSE, 1);
  curl_setopt($ch, CURLOPT_HTTPHEADER, array('Connection: Close'));
  
  
  // In wamp-like environments that do not come bundled with root authority certificates,
  // please download 'cacert.pem' from "http://curl.haxx.se/docs/caextract.html" and set 
  // the directory path of the certificate as shown below:
  // curl_setopt($ch, CURLOPT_CAINFO, dirname(__FILE__) . '/cacert.pem');
  curl_setopt($ch, CURLOPT_CAINFO, dirname(__FILE__) . '/cacert.pem');
  if( !($res = curl_exec($ch)) ) {
      //error_log("Got " . curl_error($ch) . " when processing IPN data");
      curl_close($ch);
      exit;
  }
  curl_close($ch);
  // inspect IPN validation result and act accordingly
  
  if (strcmp ($res, "VERIFIED") == 0) {
           echo '&lt;section id="download"&gt;
  &lt;h2&gt;Download song&lt;/h2&gt;
   &lt;a href="FILE_PATH"&gt;FILE Here&lt;/a&gt;
  &lt;/section&gt;';
  
      }
  
   else if (strcmp ($res, "INVALID") == 0) {
      echo "The response from IPN was: &lt;b&gt;" .$res ."&lt;/b&gt;";
  }
  ?&gt;
  </code></pre>