WordPress: Social media image tag based on featured image field

wp-social-image-tag.php

<?php
  function social_media_image() {
		global $post;
		$output = '';
		$featured_image = get_post_featured_image($post->ID, 'medium');

		if( $featured_image['id'] != null) {
			$output .= '<link rel="img_src"  type="image/jpeg" href="'.$featured_image['url'].'" />'."\n";
			$output .= '<meta property="og:image" content="'.$featured_image['url'].'"/>'."\n";

		}
		if($output != '') {
			print $output;
		}

	}
  //add social media image, based on featured image
  add_action( 'wp_head', 'social_media_image');