Writing a filter for OpenSMTPD

The first step is to define an object (most of the time you want a struct) the implements the [Filter] trait. All of this trait's methods have an empty default implementation, so you only have to implement the ones that matters to you. For each method you implement, you must use the [register] macro in order to ask OpenSMTPD to send you the corresponding events and filter requests.

The second and last step is to call the [run_filter] function with a mutable reference of your filter object.

Examples

The following filter increments a variable every time a client disconnects.

use opensmtpd::{run_filter, Filter, ReportEntry};
use opensmtpd_derive::register;

struct MyCounter {
nb: u64,
}

impl Filter for MyCounter {
#[register]
fn on_report_link_disconnect(&mut self, _entry: &ReportEntry) {
self.nb + 1;
}
}

fn main() {
let mut my_counter = MyCounter { nb: 0, };
run_filter(&mut my_counter);
}

More examples can be found in the examples directory.