1db9dbe390 2024-11-28 1: //! Simple SMTP-to-Telegram gateway. Can parse email and send them as telegram
1db9dbe390 2024-11-28 2: //! messages to specified chats, generally you specify which email address is
1db9dbe390 2024-11-28 3: //! available in configuration, everything else is sent to default address.
1db9dbe390 2024-11-28 4:
9fecd57a99 2026-10-28 5: use smol_macros::{
9fecd57a99 2026-10-28 6: LocalExecutor,
9fecd57a99 2026-10-28 7: main,
9fecd57a99 2026-10-28 8: };
9fecd57a99 2026-10-28 9:
9fecd57a99 2026-10-28 10: use std::{
9fecd57a99 2026-10-28 11: os::unix::fs::PermissionsExt,
9fecd57a99 2026-10-28 12: path::Path,
9fecd57a99 2026-10-28 13: };
9fecd57a99 2026-10-28 14:
9fecd57a99 2026-10-28 15: use clap::Parser;
9fecd57a99 2026-10-28 16: use smol::fs::metadata;
9fecd57a99 2026-10-28 17: use stacked_errors::{
9fecd57a99 2026-10-28 18: Result,
9fecd57a99 2026-10-28 19: StackableErr,
9fecd57a99 2026-10-28 20: bail,
9fecd57a99 2026-10-28 21: };
9fecd57a99 2026-10-28 22:
9fecd57a99 2026-10-28 23: use smtp2tg::mail::MailServer;
9fecd57a99 2026-10-28 24:
9fecd57a99 2026-10-28 25: /// SMTP-to-Telegram gateway
9fecd57a99 2026-10-28 26: #[derive(Parser, Debug)]
9fecd57a99 2026-10-28 27: #[command(name = "smtp2tg")]
9fecd57a99 2026-10-28 28: #[command(about = format!("SMTP-to-Telegram gateway v{}, (C) 2024 - 2026", env!("CARGO_PKG_VERSION")), long_about = None)]
9fecd57a99 2026-10-28 29: struct Args {
9fecd57a99 2026-10-28 30: /// Set configuration file location
9fecd57a99 2026-10-28 31: #[arg(short, long, default_value = "smtp2tg.toml")]
9fecd57a99 2026-10-28 32: config: String,
9fecd57a99 2026-10-28 33: }
9fecd57a99 2026-10-28 34:
9fecd57a99 2026-10-28 35: main! {
9fecd57a99 2026-10-28 36: /// Main asynchronous entry point for the application. Runs the gateway using
9fecd57a99 2026-10-28 37: /// the configuration selected on the command line.
9fecd57a99 2026-10-28 38: ///
9fecd57a99 2026-10-28 39: /// The configuration file must use owner-only permissions. Once configured,
9fecd57a99 2026-10-28 40: /// the SMTP server runs until it stops or encounters an error.
9fecd57a99 2026-10-28 41: ///
9fecd57a99 2026-10-28 42: /// # Errors
9fecd57a99 2026-10-28 43: /// Returns an error if the configuration file is missing, inaccessible,
9fecd57a99 2026-10-28 44: /// insecure, malformed, or contains invalid required settings.
9fecd57a99 2026-10-28 45: /// Also returns an error if the system hostname cannot be read or is not
9fecd57a99 2026-10-28 46: /// valid UTF-8, or if mail server initialisation fails.
9fecd57a99 2026-10-28 47: ///
9fecd57a99 2026-10-28 48: /// # Panics
9fecd57a99 2026-10-28 49: /// Panics if configuring or serving the SMTP server fails.
9fecd57a99 2026-10-28 50: async fn main (ex: &LocalExecutor<'_>) -> Result<()> {
9fecd57a99 2026-10-28 51: let args = Args::parse();
9fecd57a99 2026-10-28 52: let settings = {
9fecd57a99 2026-10-28 53: // Load configuration defaults and overrides after checking file permissions.
9fecd57a99 2026-10-28 54: let config_file = Path::new(&args.config);
9fecd57a99 2026-10-28 55: if !config_file.try_exists().stack()? {
9fecd57a99 2026-10-28 56: bail!("Configuration file not found: {config_file:?}\n\
9fecd57a99 2026-10-28 57: Hint: Ensure the file exists and the path is correct.");
9fecd57a99 2026-10-28 58: };
9fecd57a99 2026-10-28 59: {
9fecd57a99 2026-10-28 60: let meta = metadata(config_file).await.stack()?;
9fecd57a99 2026-10-28 61: if (!0o100600 & meta.permissions().mode()) > 0 {
9fecd57a99 2026-10-28 62: bail!("Configuration file permissions are insecure {config_file:?}\n\
9fecd57a99 2026-10-28 63: Current permissions: {:o}\n\
9fecd57a99 2026-10-28 64: Required: 0600 (owner read/write only).\n\
9fecd57a99 2026-10-28 65: Fix with: chmod 600 {config_file:?}",
9fecd57a99 2026-10-28 66: meta.permissions().mode());
9fecd57a99 2026-10-28 67: } }
9fecd57a99 2026-10-28 68: config::Config::builder()
9fecd57a99 2026-10-28 69: .set_default("api_gateway", "https://api.telegram.org").stack()?
9fecd57a99 2026-10-28 70: .set_default("fields", vec!["date", "from", "subject"]).stack()?
9fecd57a99 2026-10-28 71: .set_default("hostname", "smtp.2.tg").stack()?
9fecd57a99 2026-10-28 72: .set_default("listen_on", "0.0.0.0:1025").stack()?
9fecd57a99 2026-10-28 73: .set_default("domains", vec!["localhost",
9fecd57a99 2026-10-28 74: hostname::get().context("Failed to get current hostname")?
9fecd57a99 2026-10-28 75: .to_str().context("Can't convert hostname to string, bad UTF-8?")?]).stack()?
9fecd57a99 2026-10-28 76: .add_source(config::File::from(config_file))
9fecd57a99 2026-10-28 77: .build()
9fecd57a99 2026-10-28 78: .with_context(|| format!(
9fecd57a99 2026-10-28 79: "Failed to parse configuration file: {config_file:?}\n\
9fecd57a99 2026-10-28 80: Check syntax against smtp2tg.toml.example.\n\
9fecd57a99 2026-10-28 81: Common issues: missing quotes, trailing commas in inline tables, or invalid types."
9fecd57a99 2026-10-28 82: ))?
9fecd57a99 2026-10-28 83: };
9fecd57a99 2026-10-28 84:
9fecd57a99 2026-10-28 85: let listen_on = settings.get_string("listen_on").stack()?;
9fecd57a99 2026-10-28 86: let server_name = settings.get_string("hostname").stack()?;
9fecd57a99 2026-10-28 87: let core = MailServer::new(settings)?;
9fecd57a99 2026-10-28 88: let mut server = mailin_embedded::Server::new(core);
9fecd57a99 2026-10-28 89:
9fecd57a99 2026-10-28 90: // TODO: remove unwraps when mailin-embedded bumps with better error handling
9fecd57a99 2026-10-28 91: server.with_name(server_name)
9fecd57a99 2026-10-28 92: .with_ssl(mailin_embedded::SslConfig::None).unwrap()
9fecd57a99 2026-10-28 93: .with_addr(listen_on).unwrap();
9fecd57a99 2026-10-28 94: server.serve().unwrap();
9fecd57a99 2026-10-28 95:
9fecd57a99 2026-10-28 96: Ok(())
9fecd57a99 2026-10-28 97: } }