cat tag link

<?php
if( is_category() ) :
$cat_id = get_query_var('cat');
query_posts('posts_per_page=-1&cat='.$cat_id);
 if (have_posts()) :
 $posttags = array(); $the_tags = array();
 while (have_posts()) : the_post();
   $tags = get_the_tags($post->ID);
   if( $tags ){
     foreach( $tags as $tag ) {
     $posttags[] = $tag->term_id;
     };
   }
 endwhile;
$slug = get_category($cat_id)->slug;
 $posttags = array_unique( $posttags );
   foreach( $posttags as $tag ) {
   $tag = get_tag($tag);
   $the_tags[] = '<a href ="' . get_bloginfo('wpurl') . '/?category_name=' . $slug . '&tag=' . $tag->slug . '">' . $tag->name . '</a>';
   }
 sort($the_tags); //sort optional
   if( $the_tags ) {
   echo '<ul><li>' . implode("</li>\n<li>", $the_tags) . '</li></ul>';
   }
 endif; wp_reset_query();
endif;
?>