Serve a directory with mp3 files as a podcast feed

dircast.php

<?php

// put this script in web accessable directory with mp3 files and it will
// serve them as a podcast feed. can be used as index.php etc.

// absolute url for current request
function absolute_url() {
  return
    "http" . ($_SERVER["HTTPS"] != "" ? "s" : "") . 
    "://{$_SERVER["SERVER_NAME"]}" .
    (($_SERVER["HTTPS"] != "" && $_SERVER["SERVER_PORT"] != "443") ||
     ($_SERVER["HTTPS"] == "" && $_SERVER["SERVER_PORT"] != "80") ?
     ":" . $_SERVER["SERVER_PORT"] : "") .
    $_SERVER["REQUEST_URI"];
}

// remove last part of url path if present
// http://a/b -> http://a/
// http://a/ -> http:/a/
function base_url($url) {
  if ($url[strlen($url)-1] == "/") {
    return $url;
  }

  return dirname($url) . "/";
}

// url encode that is path aware
// a b/c -> a%20b/c
function rawurlencode_path($path) {
  return implode('/', array_map('rawurlencode', explode('/', $path)));
}

// collect mp3 files in path
function collect_mp3_files($path, $base_url) {
  $files = array();

  foreach(new RecursiveIteratorIterator(new RecursiveDirectoryIterator($path)) as $name => $_) {
    if (pathinfo($name, PATHINFO_EXTENSION) != "mp3") {
      continue;
    }

    $relative_path = substr($name, strlen($path) + strlen("/"));
    $files[] = array(
      "title" => $relative_path,
      "path" => $name,
      "url" => $base_url . rawurlencode_path($relative_path),
      );  
  }

  return $files;
}

// build rss dom from collection of mp3 files
function podcast_rss_for_files($title, $base_url, $files) {
  $rss_dom = new DOMDocument;
  $rss_elm = new DOMElement("rss");
  $rss_dom->appendChild($rss_elm);
  $rss_elm->setAttribute("version", "2.0");
  $channel_elm = new DOMElement("channel");
  $rss_elm->appendChild($channel_elm);
  $title_elm = new DOMElement("title");
  $channel_elm->appendChild($title_elm);
  $title_elm->appendChild(new DOMText($title));
  $channel_elm->appendChild(new DOMElement("desciption"));
  $channel_elm->appendChild(new DOMElement("link", $base_url));

  foreach($files as $file) {
    $item_elm = new DOMElement("item");
    $channel_elm->appendChild($item_elm);
    $title_elm = new DOMElement("title");
    $item_elm->appendChild($title_elm);
    $title_elm->appendChild(new DOMText($file["title"]));
    $item_elm->appendChild(new DOMElement("desciption"));
    $item_elm->appendChild(new DOMElement("link", $file["url"]));
    $item_elm->appendChild(new DOMElement("guid", $file["url"]));
    $enclosure_elm = new DOMElement("enclosure");
    $item_elm->appendChild($enclosure_elm);
    $enclosure_elm->setAttribute("url", $file["url"]);
    $enclosure_elm->setAttribute("type", "audio/mpeg");
    $enclosure_elm->setAttribute("length", filesize($file["path"]));
  }

  return $rss_dom;
}

header("Content-Type: application/rss+xml");

echo podcast_rss_for_files(
  basename(getcwd()),
  absolute_url(),
  collect_mp3_files(getcwd(), base_url(absolute_url()))
  )->saveXML();

?>