Introducing Snooker: Lightweight spam detection for blog comments

If you’ve been following the Magnificent Walrus dev logs, you’ll have read that I opted for the “Snook Algorithm” instead of adding an external dependency in the form of Akismet.

I’ve dubbed it the “Snook Algorithm” because as far as I know, it doesn’t have an official name. It’s the points-based system Jonathan uses (or perhaps used at this point) for filtering spam on snook.ca.

Each comment starts with 0 points. Points are then awarded and deducted based on a variety of rules. If a comments final score is greater than or equal to 1, the comment is considered valid. If the comments final score is 0 then it’s considered to be worth moderating. If the comments final score is below 0 then it’s considered to be spam.

The first beta of my implementation of the “Snook Algorithm” was released earlier today. You can get it via the usual platforms: crates.io and GitHub.

Example

Snooker gives the example comment below a score of -10 based off of the following patterns:

• The body has less that 2 links in it: +2 points
• The body is more that 20 characters long but contains 1 link: +1 point
• The link in the body contains one keyword considered spammy (“free”): -1 point
• The body contains one phrase considered spammy (“limited time only”): -1 point
• The body starts with a word considered spammy when it’s the first word of the comment (“nice”): -10 points
• The author field doesn’t contain http:// or https://: +0 points (unchanged)
• The url field contains a keyword considered spammy (“free”): -1 point
• None of the URLs use a TLD considered spammy: +0 points (unchanged)
• None of the URLs are longer that 30 characters: +0 points (unchanged)
• No consonant groups were found: +0 points (unchanged)
• No data was provided about the comments previously submitted with this email address: +0 points (unchanged)

use snooker::{Comment, Snooker, Status};

let comment = Comment {
    author: Some("Johnny B. Goode".to_string()),
    url: Some("http://my-free-ebook.com".to_string()),
    body: String::from("
        <p>Nice post! Check out our free (for a limited time only) eBook
        <a href=\"http://my-free-ebook.com\">here</a> that's totally relevant</p>
    "),
    previously_accepted_for_email: None,
    previously_rejected_for_email: None,
    previous_comment_bodies: None,
};

let snooker_result = Snooker::new(comment);
assert_eq!(snooker_result.score, -10);
assert_eq!(snooker_result.status, Status::Spam);