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#[cfg(feature = "pool")]
use std::sync::Arc;
use std::{fmt::Debug, time::Duration};
#[cfg(feature = "pool")]
use super::pool::sync_impl::Pool;
#[cfg(feature = "pool")]
use super::PoolConfig;
use super::{ClientId, Credentials, Error, Mechanism, Response, SmtpConnection, SmtpInfo};
#[cfg(any(feature = "native-tls", feature = "rustls-tls", feature = "boring-tls"))]
use super::{Tls, TlsParameters, SUBMISSIONS_PORT, SUBMISSION_PORT};
use crate::{address::Envelope, Transport};
/// Sends emails using the SMTP protocol
#[cfg_attr(docsrs, doc(cfg(feature = "smtp-transport")))]
#[derive(Clone)]
pub struct SmtpTransport {
#[cfg(feature = "pool")]
inner: Arc<Pool>,
#[cfg(not(feature = "pool"))]
inner: SmtpClient,
}
impl Transport for SmtpTransport {
type Ok = Response;
type Error = Error;
/// Sends an email
fn send_raw(&self, envelope: &Envelope, email: &[u8]) -> Result<Self::Ok, Self::Error> {
let mut conn = self.inner.connection()?;
let result = conn.send(envelope, email)?;
#[cfg(not(feature = "pool"))]
conn.quit()?;
Ok(result)
}
}
impl Debug for SmtpTransport {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
let mut builder = f.debug_struct("SmtpTransport");
builder.field("inner", &self.inner);
builder.finish()
}
}
impl SmtpTransport {
/// Simple and secure transport, using TLS connections to communicate with the SMTP server
///
/// The right option for most SMTP servers.
///
/// Creates an encrypted transport over submissions port, using the provided domain
/// to validate TLS certificates.
#[cfg(any(feature = "native-tls", feature = "rustls-tls", feature = "boring-tls"))]
#[cfg_attr(
docsrs,
doc(cfg(any(feature = "native-tls", feature = "rustls-tls", feature = "boring-tls")))
)]
pub fn relay(relay: &str) -> Result<SmtpTransportBuilder, Error> {
let tls_parameters = TlsParameters::new(relay.into())?;
Ok(Self::builder_dangerous(relay)
.port(SUBMISSIONS_PORT)
.tls(Tls::Wrapper(tls_parameters)))
}
/// Simple and secure transport, using STARTTLS to obtain encrypted connections
///
/// Alternative to [`SmtpTransport::relay`](#method.relay), for SMTP servers
/// that don't take SMTPS connections.
///
/// Creates an encrypted transport over submissions port, by first connecting using
/// an unencrypted connection and then upgrading it with STARTTLS. The provided
/// domain is used to validate TLS certificates.
///
/// An error is returned if the connection can't be upgraded. No credentials
/// or emails will be sent to the server, protecting from downgrade attacks.
#[cfg(any(feature = "native-tls", feature = "rustls-tls", feature = "boring-tls"))]
#[cfg_attr(
docsrs,
doc(cfg(any(feature = "native-tls", feature = "rustls-tls", feature = "boring-tls")))
)]
pub fn starttls_relay(relay: &str) -> Result<SmtpTransportBuilder, Error> {
let tls_parameters = TlsParameters::new(relay.into())?;
Ok(Self::builder_dangerous(relay)
.port(SUBMISSION_PORT)
.tls(Tls::Required(tls_parameters)))
}
/// Creates a new local SMTP client to port 25
///
/// Shortcut for local unencrypted relay (typical local email daemon that will handle relaying)
pub fn unencrypted_localhost() -> SmtpTransport {
Self::builder_dangerous("localhost").build()
}
/// Creates a new SMTP client
///
/// Defaults are:
///
/// * No authentication
/// * No TLS
/// * A 60-seconds timeout for smtp commands
/// * Port 25
///
/// Consider using [`SmtpTransport::relay`](#method.relay) or
/// [`SmtpTransport::starttls_relay`](#method.starttls_relay) instead,
/// if possible.
pub fn builder_dangerous<T: Into<String>>(server: T) -> SmtpTransportBuilder {
SmtpTransportBuilder::new(server)
}
/// Creates a `SmtpTransportBuilder` from a connection URL
///
/// The protocol, credentials, host and port can be provided in a single URL.
/// Use the scheme `smtp` for an unencrypted relay (optionally in combination with the
/// `tls` parameter to allow/require STARTTLS) or `smtps` for SMTP over TLS.
/// The path section of the url can be used to set an alternative name for
/// the HELO / EHLO command.
/// For example `smtps://username:password@smtp.example.com/client.example.com:465`
/// will set the HELO / EHLO name `client.example.com`.
///
/// <table>
/// <thead>
/// <tr>
/// <th>scheme</th>
/// <th>tls parameter</th>
/// <th>example</th>
/// <th>remarks</th>
/// </tr>
/// </thead>
/// <tbody>
/// <tr>
/// <td>smtps</td>
/// <td>-</td>
/// <td>smtps://smtp.example.com</td>
/// <td>SMTP over TLS, recommended method</td>
/// </tr>
/// <tr>
/// <td>smtp</td>
/// <td>required</td>
/// <td>smtp://smtp.example.com?tls=required</td>
/// <td>SMTP with STARTTLS required, when SMTP over TLS is not available</td>
/// </tr>
/// <tr>
/// <td>smtp</td>
/// <td>opportunistic</td>
/// <td>smtp://smtp.example.com?tls=opportunistic</td>
/// <td>
/// SMTP with optionally STARTTLS when supported by the server.
/// Caution: this method is vulnerable to a man-in-the-middle attack.
/// Not recommended for production use.
/// </td>
/// </tr>
/// <tr>
/// <td>smtp</td>
/// <td>-</td>
/// <td>smtp://smtp.example.com</td>
/// <td>Unencrypted SMTP, not recommended for production use.</td>
/// </tr>
/// </tbody>
/// </table>
///
/// ```rust,no_run
/// use lettre::{
/// message::header::ContentType, transport::smtp::authentication::Credentials, Message,
/// SmtpTransport, Transport,
/// };
///
/// let email = Message::builder()
/// .from("NoBody <nobody@domain.tld>".parse().unwrap())
/// .reply_to("Yuin <yuin@domain.tld>".parse().unwrap())
/// .to("Hei <hei@domain.tld>".parse().unwrap())
/// .subject("Happy new year")
/// .header(ContentType::TEXT_PLAIN)
/// .body(String::from("Be happy!"))
/// .unwrap();
///
/// // Open a remote connection to example
/// let mailer = SmtpTransport::from_url("smtps://username:password@smtp.example.com:465")
/// .unwrap()
/// .build();
///
/// // Send the email
/// match mailer.send(&email) {
/// Ok(_) => println!("Email sent successfully!"),
/// Err(e) => panic!("Could not send email: {e:?}"),
/// }
/// ```
#[cfg(any(feature = "native-tls", feature = "rustls-tls", feature = "boring-tls"))]
#[cfg_attr(
docsrs,
doc(cfg(any(feature = "native-tls", feature = "rustls-tls", feature = "boring-tls")))
)]
pub fn from_url(connection_url: &str) -> Result<SmtpTransportBuilder, Error> {
super::connection_url::from_connection_url(connection_url)
}
/// Tests the SMTP connection
///
/// `test_connection()` tests the connection by using the SMTP NOOP command.
/// The connection is closed afterward if a connection pool is not used.
pub fn test_connection(&self) -> Result<bool, Error> {
let mut conn = self.inner.connection()?;
let is_connected = conn.test_connected();
#[cfg(not(feature = "pool"))]
conn.quit()?;
Ok(is_connected)
}
}
/// Contains client configuration.
/// Instances of this struct can be created using functions of [`SmtpTransport`].
#[derive(Debug, Clone)]
pub struct SmtpTransportBuilder {
info: SmtpInfo,
#[cfg(feature = "pool")]
pool_config: PoolConfig,
}
/// Builder for the SMTP `SmtpTransport`
impl SmtpTransportBuilder {
// Create new builder with default parameters
pub(crate) fn new<T: Into<String>>(server: T) -> Self {
let new = SmtpInfo {
server: server.into(),
..Default::default()
};
Self {
info: new,
#[cfg(feature = "pool")]
pool_config: PoolConfig::default(),
}
}
/// Set the name used during EHLO
pub fn hello_name(mut self, name: ClientId) -> Self {
self.info.hello_name = name;
self
}
/// Set the authentication mechanism to use
pub fn credentials(mut self, credentials: Credentials) -> Self {
self.info.credentials = Some(credentials);
self
}
/// Set the authentication mechanism to use
pub fn authentication(mut self, mechanisms: Vec<Mechanism>) -> Self {
self.info.authentication = mechanisms;
self
}
/// Set the timeout duration
pub fn timeout(mut self, timeout: Option<Duration>) -> Self {
self.info.timeout = timeout;
self
}
/// Set the port to use
pub fn port(mut self, port: u16) -> Self {
self.info.port = port;
self
}
/// Set the TLS settings to use
#[cfg(any(feature = "native-tls", feature = "rustls-tls", feature = "boring-tls"))]
#[cfg_attr(
docsrs,
doc(cfg(any(feature = "native-tls", feature = "rustls-tls", feature = "boring-tls")))
)]
pub fn tls(mut self, tls: Tls) -> Self {
self.info.tls = tls;
self
}
/// Use a custom configuration for the connection pool
///
/// Defaults can be found at [`PoolConfig`]
#[cfg(feature = "pool")]
#[cfg_attr(docsrs, doc(cfg(feature = "pool")))]
pub fn pool_config(mut self, pool_config: PoolConfig) -> Self {
self.pool_config = pool_config;
self
}
/// Build the transport
///
/// If the `pool` feature is enabled, an `Arc` wrapped pool is created.
/// Defaults can be found at [`PoolConfig`]
pub fn build(self) -> SmtpTransport {
let client = SmtpClient { info: self.info };
#[cfg(feature = "pool")]
let client = Pool::new(self.pool_config, client);
SmtpTransport { inner: client }
}
}
/// Build client
#[derive(Debug, Clone)]
pub struct SmtpClient {
info: SmtpInfo,
}
impl SmtpClient {
/// Creates a new connection directly usable to send emails
///
/// Handles encryption and authentication
pub fn connection(&self) -> Result<SmtpConnection, Error> {
#[allow(clippy::match_single_binding)]
let tls_parameters = match self.info.tls {
#[cfg(any(feature = "native-tls", feature = "rustls-tls", feature = "boring-tls"))]
Tls::Wrapper(ref tls_parameters) => Some(tls_parameters),
_ => None,
};
#[allow(unused_mut)]
let mut conn = SmtpConnection::connect::<(&str, u16)>(
(self.info.server.as_ref(), self.info.port),
self.info.timeout,
&self.info.hello_name,
tls_parameters,
None,
)?;
#[cfg(any(feature = "native-tls", feature = "rustls-tls", feature = "boring-tls"))]
match self.info.tls {
Tls::Opportunistic(ref tls_parameters) => {
if conn.can_starttls() {
conn.starttls(tls_parameters, &self.info.hello_name)?;
}
}
Tls::Required(ref tls_parameters) => {
conn.starttls(tls_parameters, &self.info.hello_name)?;
}
_ => (),
}
if let Some(credentials) = &self.info.credentials {
conn.auth(&self.info.authentication, credentials)?;
}
Ok(conn)
}
}
#[cfg(test)]
mod tests {
use crate::{
transport::smtp::{authentication::Credentials, client::Tls},
SmtpTransport,
};
#[test]
fn transport_from_url() {
let builder = SmtpTransport::from_url("smtp://127.0.0.1:2525").unwrap();
assert_eq!(builder.info.port, 2525);
assert!(matches!(builder.info.tls, Tls::None));
assert_eq!(builder.info.server, "127.0.0.1");
let builder =
SmtpTransport::from_url("smtps://username:password@smtp.example.com:465").unwrap();
assert_eq!(builder.info.port, 465);
assert_eq!(
builder.info.credentials,
Some(Credentials::new(
"username".to_owned(),
"password".to_owned()
))
);
assert!(matches!(builder.info.tls, Tls::Wrapper(_)));
assert_eq!(builder.info.server, "smtp.example.com");
let builder = SmtpTransport::from_url(
"smtps://user%40example.com:pa$$word%3F%22!@smtp.example.com:465",
)
.unwrap();
assert_eq!(builder.info.port, 465);
assert_eq!(
builder.info.credentials,
Some(Credentials::new(
"user@example.com".to_owned(),
"pa$$word?\"!".to_owned()
))
);
assert!(matches!(builder.info.tls, Tls::Wrapper(_)));
assert_eq!(builder.info.server, "smtp.example.com");
let builder =
SmtpTransport::from_url("smtp://username:password@smtp.example.com:587?tls=required")
.unwrap();
assert_eq!(builder.info.port, 587);
assert_eq!(
builder.info.credentials,
Some(Credentials::new(
"username".to_owned(),
"password".to_owned()
))
);
assert!(matches!(builder.info.tls, Tls::Required(_)));
let builder = SmtpTransport::from_url(
"smtp://username:password@smtp.example.com:587?tls=opportunistic",
)
.unwrap();
assert_eq!(builder.info.port, 587);
assert!(matches!(builder.info.tls, Tls::Opportunistic(_)));
let builder = SmtpTransport::from_url("smtps://smtp.example.com").unwrap();
assert_eq!(builder.info.port, 465);
assert_eq!(builder.info.credentials, None);
assert!(matches!(builder.info.tls, Tls::Wrapper(_)));
}
}