make SMTP authentication optionnal, let lettre pick the better auth mechanism

src/mail.rs

@@ -3,7 +3,7 @@ use native_tls::TlsConnector;
 use native_tls::{Protocol};
 use lettre::{EmailTransport, SmtpTransport, ClientTlsParameters, ClientSecurity};
 use lettre::smtp::{ConnectionReuseParameters, SmtpTransportBuilder};
-use lettre::smtp::authentication::{Credentials, Mechanism};
+use lettre::smtp::authentication::Credentials;
 use lettre_email::EmailBuilder;
 
 use MailConfig;
@@ -11,10 +11,7 @@ use MailConfig;
 fn mailer(config: &MailConfig) -> SmtpTransport {
     let client_security = if config.smtp_ssl {
         let mut tls_builder = TlsConnector::builder().unwrap();
-        tls_builder.supported_protocols(&[
-            Protocol::Tlsv10, Protocol::Tlsv11, Protocol::Tlsv12
-        ]).unwrap();
-
+        tls_builder.supported_protocols(&[Protocol::Tlsv11, Protocol::Tlsv12]).unwrap();
         ClientSecurity::Required(
             ClientTlsParameters::new(config.smtp_host.to_owned(), tls_builder.build().unwrap())
         )
@@ -22,12 +19,21 @@ fn mailer(config: &MailConfig) -> SmtpTransport {
         ClientSecurity::None
     };
 
-    SmtpTransportBuilder::new((config.smtp_host.to_owned().as_str(), config.smtp_port), client_security)
-        .unwrap()
-        .credentials(Credentials::new(config.smtp_username.to_owned(), config.smtp_password.to_owned()))
-        .authentication_mechanism(Mechanism::Login)
+    let smtp_transport = SmtpTransportBuilder::new(
+        (config.smtp_host.to_owned().as_str(), config.smtp_port),
+        client_security
+    ).unwrap();
+
+    let smtp_transport = match (&config.smtp_username, &config.smtp_password) {
+        (Some(username), Some(password)) => {
+            smtp_transport.credentials(Credentials::new(username.to_owned(), password.to_owned()))
+        },
+        (_, _) => smtp_transport,
+    };
+
+    smtp_transport
         .smtp_utf8(true)
-        .connection_reuse(ConnectionReuseParameters::ReuseUnlimited)
+        .connection_reuse(ConnectionReuseParameters::NoReuse)
         .build()
 }
 

src/main.rs

@@ -163,13 +163,13 @@ pub struct MailConfig {
     smtp_port: u16,
     smtp_ssl: bool,
     smtp_from: String,
-    smtp_username: String,
-    smtp_password: String,
+    smtp_username: Option<String>,
+    smtp_password: Option<String>,
 }
 
 impl MailConfig {
     fn load() -> Option<Self> {
-        let smtp_host = util::parse_option_string(env::var("SMTP_HOST").ok());
+        let smtp_host = env::var("SMTP_HOST").ok();
         
         // When SMTP_HOST is absent, we assume the user does not want to enable it.
         if smtp_host.is_none() {
@@ -186,24 +186,24 @@ impl MailConfig {
                 }
             });
 
+        let smtp_username = env::var("SMTP_USERNAME").ok();
+        let smtp_password = env::var("SMTP_PASSWORD").ok().or_else(|| {
+            if smtp_username.as_ref().is_some() {
+                println!("Please specify SMTP_PASSWORD to enable SMTP support.");
+                exit(1);
+            } else {
+                None
+            }
+        });
+
         Some(MailConfig {
             smtp_host: smtp_host.unwrap(),
             smtp_port: smtp_port,
             smtp_ssl: smtp_ssl,
             smtp_from: util::parse_option_string(env::var("SMTP_FROM").ok())
-                .unwrap_or("bitwarden@localhost".to_string()),
-            // If username or password is not specified and SMTP support seems to be wanted,
-            // don't let the app start: the configuration is clearly incomplete.
-            smtp_username: util::parse_option_string(env::var("SMTP_USERNAME").ok())
-                .unwrap_or_else(|| {
-                    println!("Please specify SMTP_USERNAME to enable SMTP support.");
-                    exit(1);
-                }),
-            smtp_password: util::parse_option_string(env::var("SMTP_PASSWORD").ok())
-                .unwrap_or_else(|| {
-                    println!("Please specify SMTP_PASSWORD to enable SMTP support.");
-                    exit(1);
-                }),
+                .unwrap_or("bitwarden-rs@localhost".to_string()),
+            smtp_username: smtp_username,
+            smtp_password: smtp_password,
         })
     }
 }