avoid guestbook from spam

Here is a simple rudimentary integration of the spam-module 2.1.2 it's working fine for me with guestbook 4.7.0 on drupal 4.7.2.

There are just a few lines of code to insert in guestbook.module

In guestbook.module do:

after line 1 add the code to include spam.module:
include_once "modules/spam/spam.module";

at the end of guestbook.module before "?>" insert the following function:

function callback_spam($source, $id, $header, $body, $probability, $old, $action)
{
   if ($probability > 98 ) {
        $msgtext = t("Entry is spam: ") . $header . " " .$body  . " probability: " .$probability;
        watchdog('guestbook', $msgtext, WATCHDOG_WARNING ); 
        drupal_set_message( $msgtext,'error' );    
        return TRUE;
   }
   return FALSE;
}

after line 391 add the code to call spam-module to check the entry for spam, before inserting the entry

  //  Is this spam?
  $spamcheck = $edit['anonname'] .  " " . $edit['anonemail'] . " ".$edit['anonwebsite'] ; 
  if (spam_content_filter("guestbook", 1, $spamcheck, $message, callback_spam) == TRUE ) {
     return;
  }

the new code should look like:

  // Make sure this isn't a dupe
  $result = db_query("SELECT message FROM {guestbook} WHERE recipient = %d ORDER BY id DESC LIMIT 1", $uid);
  $entry = db_fetch_array($result);
  if ($entry["message"] == $message) {
    return;
  }
  
  //  Is this spam?
  $spamcheck = $edit['anonname'] .  " " . $edit['anonemail'] . " ".$edit['anonwebsite'] ; 
   if (spam_content_filter("guestbook", 1, $spamcheck, $message, callback_spam) == TRUE ) {
       return;
   }
	
  // Insert new message
  if (_guestbook_access('post', $uid) == 'allowed') {
    if ($user->uid == 0) {
      // anonymous user
      $entryid = db_next_id('{guestbook}_id');
      $result = db_query("INSERT INTO {guestbook} (id, anonname, anonemail, anonwebsite, author, recipient, message, created)
        VALUES('%d', '%s', '%s', '%s', '%d', '%d', '%s', '%d')", $entryid, $edit['anonname'], $edit['anonemail'], $edit['anonwebsite'], $user->uid, $uid, $message, time()); 
    }
    else if ($user->uid > 0) {
      // registered user
      $entryid = db_next_id('{guestbook}_id');
      $result = db_query("INSERT INTO {guestbook} (id,author,recipient,message,created)
        VALUES('%d', '%d', '%d', '%s', '%d')", $entryid, $user->uid, $uid, $message, time()); 
    }

ready!!!

Is your spam-module generally working? Is it working for example in comments?
Did you code everything correct? Try to filter everything as spam, by coding:

function callback_spam($source, $id, $header, $body, $probability, $old, $action)
{
$msgtext = t("Entry is spam: ") . $header . " " .$body . " probability: " .$probability;
watchdog('guestbook', $msgtext, WATCHDOG_WARNING );
drupal_set_message( $msgtext,'error' );
return TRUE;
}

Now every entry must be spam. If it isn't so, the integration of the spam-module is not correct.

The hack is working very well for me.
Good luck