docs: improve SMTP transport from_url (#1032)

This commit is contained in:
Paolo Barbolini
2025-02-02 13:38:03 +01:00
committed by GitHub
parent 55c7f57f25
commit 32e066464a
2 changed files with 137 additions and 107 deletions

View File

@@ -191,54 +191,72 @@ where
/// Creates a `AsyncSmtpTransportBuilder` 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`.
/// The protocol, credentials, host, port and EHLO name can be provided
/// in a single URL. This may be simpler than having to configure SMTP
/// through multiple configuration parameters and then having to pass
/// those options to lettre.
///
/// <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>
/// The URL is created in the following way:
/// `scheme://user:pass@hostname:port/ehlo-name?tls=TLS`.
///
/// `user` (Username) and `pass` (Password) are optional in case the
/// SMTP relay doesn't require authentication. When `port` is not
/// configured it is automatically determined based on the `scheme`.
/// `ehlo-name` optionally overwrites the hostname sent for the EHLO
/// command. `TLS` controls whether STARTTLS is simply enabled
/// (`opportunistic` - not enough to prevent man-in-the-middle attacks)
/// or `required` (require the server to upgrade the connection to
/// STARTTLS, otherwise fail on suspicion of main-in-the-middle attempt).
///
/// Use the following table to construct your SMTP url:
///
/// | scheme | `tls` query parameter | example | default port | remarks |
/// | ------- | --------------------- | -------------------------------------------------- | ------------ | ------------------------------------------------------------------------------------------------------------------------------------- |
/// | `smtps` | unset | `smtps://user:pass@hostname:port` | 465 | SMTP over TLS, recommended method |
/// | `smtp` | `required` | `smtp://user:pass@hostname:port?tls=required` | 587 | SMTP with STARTTLS required, when SMTP over TLS is not available |
/// | `smtp` | `opportunistic` | `smtp://user:pass@hostname:port?tls=opportunistic` | 587 | SMTP with optionally STARTTLS when supported by the server. Not suitable for production use: vulnerable to a man-in-the-middle attack |
/// | `smtp` | unset | `smtp://user:pass@hostname:port` | 587 | Always unencrypted SMTP. Not suitable for production use: sends all data unencrypted |
///
/// IMPORTANT: some parameters like `user` and `pass` cannot simply
/// be concatenated to construct the final URL because special characters
/// contained within the parameter may confuse the URL decoder.
/// Manually URL encode the parameters before concatenating them or use
/// a proper URL encoder, like the following cargo script:
///
/// ```rust
/// # let _ = r#"
/// #!/usr/bin/env cargo
///
/// //! ```cargo
/// //! [dependencies]
/// //! url = "2"
/// //! ```
/// # "#;
///
/// use url::Url;
///
/// fn main() {
/// // don't touch this line
/// let mut url = Url::parse("foo://bar").unwrap();
///
/// // configure the scheme (`smtp` or `smtps`) here.
/// url.set_scheme("smtps").unwrap();
/// // configure the username and password.
/// // remove the following two lines if unauthenticated.
/// url.set_username("username").unwrap();
/// url.set_password(Some("password")).unwrap();
/// // configure the hostname
/// url.set_host(Some("smtp.example.com")).unwrap();
/// // configure the port - only necessary if using a non-default port
/// url.set_port(Some(465)).unwrap();
/// // configure the EHLO name
/// url.set_path("ehlo-name");
///
/// println!("{url}");
/// }
/// ```
///
/// The connection URL can then be used in the following way:
///
/// ```rust,no_run
/// use lettre::{
@@ -262,15 +280,11 @@ where
/// let mailer: AsyncSmtpTransport<Tokio1Executor> =
/// AsyncSmtpTransport::<Tokio1Executor>::from_url(
/// "smtps://username:password@smtp.example.com:465",
/// )
/// .unwrap()
/// )?
/// .build();
///
/// // Send the email
/// match mailer.send(email).await {
/// Ok(_) => println!("Email sent successfully!"),
/// Err(e) => panic!("Could not send email: {e:?}"),
/// }
/// mailer.send(email).await?;
/// # Ok(())
/// # }
/// ```

View File

@@ -139,54 +139,72 @@ impl SmtpTransport {
/// 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`.
/// The protocol, credentials, host, port and EHLO name can be provided
/// in a single URL. This may be simpler than having to configure SMTP
/// through multiple configuration parameters and then having to pass
/// those options to lettre.
///
/// <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>
/// The URL is created in the following way:
/// `scheme://user:pass@hostname:port/ehlo-name?tls=TLS`.
///
/// `user` (Username) and `pass` (Password) are optional in case the
/// SMTP relay doesn't require authentication. When `port` is not
/// configured it is automatically determined based on the `scheme`.
/// `ehlo-name` optionally overwrites the hostname sent for the EHLO
/// command. `TLS` controls whether STARTTLS is simply enabled
/// (`opportunistic` - not enough to prevent man-in-the-middle attacks)
/// or `required` (require the server to upgrade the connection to
/// STARTTLS, otherwise fail on suspicion of main-in-the-middle attempt).
///
/// Use the following table to construct your SMTP url:
///
/// | scheme | `tls` query parameter | example | default port | remarks |
/// | ------- | --------------------- | -------------------------------------------------- | ------------ | ------------------------------------------------------------------------------------------------------------------------------------- |
/// | `smtps` | unset | `smtps://user:pass@hostname:port` | 465 | SMTP over TLS, recommended method |
/// | `smtp` | `required` | `smtp://user:pass@hostname:port?tls=required` | 587 | SMTP with STARTTLS required, when SMTP over TLS is not available |
/// | `smtp` | `opportunistic` | `smtp://user:pass@hostname:port?tls=opportunistic` | 587 | SMTP with optionally STARTTLS when supported by the server. Not suitable for production use: vulnerable to a man-in-the-middle attack |
/// | `smtp` | unset | `smtp://user:pass@hostname:port` | 587 | Always unencrypted SMTP. Not suitable for production use: sends all data unencrypted |
///
/// IMPORTANT: some parameters like `user` and `pass` cannot simply
/// be concatenated to construct the final URL because special characters
/// contained within the parameter may confuse the URL decoder.
/// Manually URL encode the parameters before concatenating them or use
/// a proper URL encoder, like the following cargo script:
///
/// ```rust
/// # let _ = r#"
/// #!/usr/bin/env cargo
///
/// //! ```cargo
/// //! [dependencies]
/// //! url = "2"
/// //! ```
/// # "#;
///
/// use url::Url;
///
/// fn main() {
/// // don't touch this line
/// let mut url = Url::parse("foo://bar").unwrap();
///
/// // configure the scheme (`smtp` or `smtps`) here.
/// url.set_scheme("smtps").unwrap();
/// // configure the username and password.
/// // remove the following two lines if unauthenticated.
/// url.set_username("username").unwrap();
/// url.set_password(Some("password")).unwrap();
/// // configure the hostname
/// url.set_host(Some("smtp.example.com")).unwrap();
/// // configure the port - only necessary if using a non-default port
/// url.set_port(Some(465)).unwrap();
/// // configure the EHLO name
/// url.set_path("ehlo-name");
///
/// println!("{url}");
/// }
/// ```
///
/// The connection URL can then be used in the following way:
///
/// ```rust,no_run
/// use lettre::{
@@ -194,6 +212,7 @@ impl SmtpTransport {
/// SmtpTransport, Transport,
/// };
///
/// # fn main() -> Result<(), Box<dyn std::error::Error>> {
/// let email = Message::builder()
/// .from("NoBody <nobody@domain.tld>".parse().unwrap())
/// .reply_to("Yuin <yuin@domain.tld>".parse().unwrap())
@@ -204,15 +223,12 @@ impl SmtpTransport {
/// .unwrap();
///
/// // Open a remote connection to example
/// let mailer = SmtpTransport::from_url("smtps://username:password@smtp.example.com:465")
/// .unwrap()
/// .build();
/// let mailer = SmtpTransport::from_url("smtps://username:password@smtp.example.com")?.build();
///
/// // Send the email
/// match mailer.send(&email) {
/// Ok(_) => println!("Email sent successfully!"),
/// Err(e) => panic!("Could not send email: {e:?}"),
/// }
/// mailer.send(&email)?;
/// # Ok(())
/// # }
/// ```
#[cfg(any(feature = "native-tls", feature = "rustls-tls", feature = "boring-tls"))]
#[cfg_attr(