WordPress Filter - Append permalink to Pardot iframe src attribute

wordpress-pardot-iframe-src-filter.php

<?php

/**
 * Finds all Pardot form iframes and appends a ?embedded_on= query parameter to the source. 
 * Very useful for fixing the crappy issues with pardot tracking...
 */
add_filter( 'the_content', 'pardot_iframe_src_filter', 99, 1 );
function pardot_iframe_src_filter( $content ) {

	global $post;
 	$permalink_path = wp_make_link_relative( get_permalink( $post->ID ) );
  
  	// Replace: your\.pardotdomain\.com with the TLD you use for serving pardot forms.
	$content = preg_replace('#\<iframe(.*?)\ssrc\=\"http(s)?:\/\/(your\.pardotdomain\.com|go\.pardot\.com)(.*?)\"(.*?)\>#i',
                        '<iframe$1 src="http$2://$3$4?embedded_on=' . urlencode( $permalink_path ) . '"$5>',  $content);

	return $content;

}