drupal/modules/statistics.module

<?php

if (variable_get("referer", 0)) {
  if ($referer = getenv("HTTP_REFERER")) {
    db_query("INSERT INTO referer (URL, timestamp) values ('". check_input($referer) ."', '". time() ."')");
  }
}

function statistics_cron() {
  db_query("DELETE FROM referer WHERE ". time() ." - timestamp > ". variable_get("referer_clear", 604800));
}

function statistics_perm() {
  return array("access statistics");
}

function statistics_conf_options() {
  $period = array(3600 => format_interval(3600), 10800 => format_interval(10800), 21600 => format_interval(21600), 32400 => format_interval(32400), 43200 => format_interval(43200), 86400 => format_interval(86400), 172800 => format_interval(172800), 259200 => format_interval(259200), 604800 => format_interval(604800), 1209600 => format_interval(1209600), 2419200 => format_interval(2419200), 1000000000 => t("Never"));
  $output .= form_select(t("Track referers"), "referer", variable_get("referer", 0), array("Disabled", "Enabled"), "If enabled, Drupal will count how many times your website is referred to by other websites.");
  $output .= form_select(t("Discard referers older than"), "referer_clear", variable_get("referer_clear", 604800), $period, "The time referer entries should be kept.  Older entries will be automatically discarded.  Requires crontab.");  return $output;
}

function statistics_referer() {
  $result = db_query("SELECT url, COUNT(url) AS count FROM referer WHERE url NOT LIKE '". path_uri() ."%' GROUP BY url ORDER BY count DESC");

  $output .= "<P>Referers of the last ". format_interval(variable_get("referer_clear", 604800)) .":</P>\n";

  $output .= "<H3>External referers</H3>\n";
  $output .= "<TABLE BORDER=\"1\" CELLPADDING=\"3\" CELLSPACING=\"0\">\n";
  $output .= " <TR><TH>URL</TH><TH>number</TH></TR>\n";
  while ($referer = db_fetch_object($result)) {
    $output .= "<TR><TD><A HREF=\"". check_output($referer->url) ."\">". substr(check_output($referer->url), 0, 100) ."</A></TD><TD>". check_output($referer->count) ."</TD></TR>";
  }
  $output .= "</TABLE>\n";

  $result = db_query("SELECT url, COUNT(url) AS count FROM referer WHERE url LIKE '". path_uri() ."%' GROUP BY url ORDER BY count DESC");

  $output .= "<H3>Internal referers</H3>\n";
  $output .= "<TABLE BORDER=\"1\" CELLPADDING=\"3\" CELLSPACING=\"0\">\n";
  $output .= " <TR><TH>URL</TH><TH>number</TH></TR>\n";
  while ($referer = db_fetch_object($result)) {
    $output .= "<TR><TD><A HREF=\"". check_output($referer->url) ."\">". substr(check_output($referer->url), 0, 100) ."</A></TD><TD>". check_output($referer->count) ."</TD></TR>";
  }
  $output .= "</TABLE>\n";

  return $output;
}

function statistics_admin() {
  global $user;

  if (user_access($user, "access statistics")) {
    print statistics_referer();
  }
}

?>