rust-opensmtpd/opensmtpd/examples/rm_x-originating-ip.rs

use opensmtpd::{return_data_line, run_filter, Filter, FilterEntry};
use opensmtpd_derive::register;

pub const HEADER_NAME: &str = "x-originating-ip:";
pub const HEADER_LEN: usize = 17;

struct RmXOriginatingIp {}

impl Filter for RmXOriginatingIp {
	#[register]
	fn on_filter_data_line(&mut self, entry: &FilterEntry, data_line: &[u8]) {
		if data_line.len() >= HEADER_LEN {
			let head_start = data_line[..HEADER_LEN].to_vec();
			if let Ok(s) = String::from_utf8(head_start) {
				if s.to_lowercase() == HEADER_NAME {
					return;
				}
			}
		}
		return_data_line(entry, data_line);
	}
}

fn main() {
	let mut my_filter = RmXOriginatingIp {};
	run_filter(&mut my_filter);
}