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[rbdr/olden-mail] / src / main.rs

//! # olden-mail
//!
//! `olden-mail` is an IMAP & SMTP proxy that allows you to connect to SSL
//! enabled mail servers using insecure plaintext connections.
//!
//! This is of course very insecure, but it's intended to allow vintage
//! computers that don't have SSL capability or ther right ciphers to still
//! be used for e-mail.
//!
//! ## Installation
//!
//! ### Pre-built binaries and packages
//!
//! Binaries are available for macos and linux, for both aarch64 and `x86_64`
//! from <https://build.r.bdr.sh/olden-mail>, including `.deb` and `.rpm`
//! packages.
//!
//! ### Homebrew
//!
//! You can also install this on macos via homebrew.
//!
//! ```
//! % brew tap rbdr/apps git@git.sr.ht:~rbdr/homebrew-apps
//! % brew install rbdr/apps/olden-mail
//! ```
//!
//! ### From source
//!
//! You can run `make` for a debug build, or `make -e profile=release` for a
//! release build.
//!
//! ## Usage
//!
//! The proxy requires you to set environment variables, but otherwise takes
//! no options.
//!
//! * `LOCAL_IMAP_PORT` u16, the port in which the server will listen for
//!   IMAP clients. Defaults to 143.
//! * `LOCAL_IMAP_BIND_ADDRESS` String, the address on which to listen for
//!   IMAP clients. Defaults to 0.0.0.0.
//! * `REMOTE_IMAP_PORT` u16, the port to which the server will forward the
//!   IMAP messages. Defaults to 993.
//! * `REMOTE_IMAP_HOST` String, the host to which the server will forward the
//!   IMAP messages. Required.
//!
//! * `LOCAL_SMTP_PORT` u16, the port in which the server will listen for
//!   SMTP clients. Defaults to 25.
//! * `LOCAL_SMTP_BIND_ADDRESS` String, the address on which to listen for
//!   SMTP clients. Defaults to 0.0.0.0.
//! * `REMOTE_SMTP_PORT` u16, the port to which the server will forward the
//!   SMTP messages. Defaults to 465.
//! * `REMOTE_SMTP_HOST` String, the host to which the server will forward the
//!   SMTP messages. Required.
//!
//! This means the minimum invocation is this (Shown here with inline
//! environment variables)
//!
//! ```
//! % REMOTE_IMAP_HOST=imap.coolmailsite.example REMOTE_SMTP_HOST=smtp.coolmailsite.example olden-mail
//! ```
//!
//! ## Debugging
//!
//! You can control how much it prints by setting `RUST_LOG`. Setting it to
//! `debug` will output the whole protocol stream. The default level is
//! `info`.

use env_logger::{Builder, Env};
use log::{error, info};
use std::process::exit;
use std::sync::mpsc;

mod configuration;
mod proxy;

use configuration::Configuration;
use proxy::Server;

fn main() {
    Builder::from_env(Env::default().default_filter_or("info"))
        .format_timestamp_millis()
        .init();

    let configuration = Configuration::new().unwrap_or_else(|error| {
        error!("{error}");
        exit(1);
    });

    let (tx, rx) = mpsc::channel();

    let mut imap_proxy = Server::new(configuration.imap_configuration);
    let mut smtp_proxy = Server::new(configuration.smtp_configuration);

    ctrlc::set_handler(move || {
        info!("Shutting down...");
        imap_proxy.shutdown();
        smtp_proxy.shutdown();
        let _ = tx.send(());
    })
    .unwrap_or_else(|e| {
        error!("Error setting Ctrl-C handler: {e}");
        std::process::exit(1);
    });

    // Block until we get a shutdown
    rx.recv().unwrap_or(());
}