//! SMTP-to-Telegram gateway main library.
//!
//! This module provides the core functionality for receiving emails via SMTP
//! and forwarding them to Telegram chats.
//!
//! As we are not actually exporting this lib there would be no local Error's
//! for now, everything will be just .stack()?'ed and propagated like in real
//! bin The lib here is just to separate all tests from main code into tests/
pub mod mail;
mod telegram;
pub mod utils;
use crate::mail::MailServer;
use std::{
io::Cursor,
os::unix::fs::PermissionsExt,
path::Path,
};
use clap::Parser;
use smol::{
fs::metadata,
};
use stacked_errors::{
Result,
StackableErr,
bail,
};
/// SMTP-to-Telegram gateway
#[derive(Parser, Debug)]
#[command(name = "smtp2tg")]
#[command(about = format!("SMTP-to-Telegram gateway v{}, (C) 2024 - 2026", env!("CARGO_PKG_VERSION")), long_about = None)]
struct Args {
/// Set configuration file location
#[arg(short, long, default_value = "smtp2tg.toml")]
config: String,
}
/// Main asynchronous entry point for the application.
///
/// Parses command-line arguments, loads configuration, and starts the SMTP
/// server.
///
/// # Errors
/// Returns an error if configuration is invalid, files are inaccessible, or
/// server fails to start.
pub async fn async_main () -> Result<()> {
let args = Args::parse();
let config_file = Path::new(&args.config);
if !config_file.exists() {
bail!("can't read configuration from {config_file:?}");
};
{
let meta = metadata(config_file).await.stack()?;
if (!0o100600 & meta.permissions().mode()) > 0 {
bail!("other users can read or write config file {config_file:?}\n\
File permissions: {:o}", meta.permissions().mode());
}
}
let settings: config::Config = config::Config::builder()
.set_default("api_gateway", "https://api.telegram.org").stack()?
.set_default("fields", vec!["date", "from", "subject"]).stack()?
.set_default("hostname", "smtp.2.tg").stack()?
.set_default("listen_on", "0.0.0.0:1025").stack()?
.set_default("domains", vec!["localhost",
hostname::get().context("Failed to get current hostname")?
.to_str().context("Can't convert hostname to string, bad UTF-8?")?]).stack()?
.add_source(config::File::from(config_file))
.build()
.with_context(|| format!("[{config_file:?}] there was an error reading config\n\
\tplease consult \"smtp2tg.toml.example\" for details"))?;
let listen_on = settings.get_string("listen_on").stack()?;
let server_name = settings.get_string("hostname").stack()?;
let core = MailServer::new(settings)?;
let mut server = mailin_embedded::Server::new(core);
// TODO: remove unwraps when mailin-embedded bumps with better error handling
server.with_name(server_name)
.with_ssl(mailin_embedded::SslConfig::None).unwrap()
.with_addr(listen_on).unwrap();
server.serve().unwrap();
Ok(())
}