Add PLAIN authentication mecanism

src/client/authentication/mod.rs

@@ -0,0 +1,22 @@
+// Copyright 2014 Alexis Mousset. See the COPYRIGHT
+// file at the top-level directory of this distribution.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+//! PLAIN authentication mecanism
+
+pub mod plain;
+
+/// Trait representing an authentication mecanism
+pub trait AuthenticationMecanism {
+    /// Create an authentication
+    fn new(username: String, password: String) -> Self;
+    /// Initial response if available
+    fn initial_response(&self) -> Option<String>;
+    /// Response to the given challenge
+    fn response(&self, challenge: &str) -> String;
+}

src/client/authentication/plain.rs

@@ -0,0 +1,39 @@
+// Copyright 2014 Alexis Mousset. See the COPYRIGHT
+// file at the top-level directory of this distribution.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+//! Authentication mecanisms
+
+use common::NUL;
+use client::authentication::AuthenticationMecanism;
+
+struct Plain {
+    identity: String,
+    username: String,
+    password: String,
+}
+
+impl AuthenticationMecanism for Plain {
+    fn new(username: String, password: String) -> Plain {
+        Plain {
+            identity: "".to_string(),
+            username: username,
+            password: password,
+        }
+    }
+
+    fn initial_response(&self) -> Option<String> {
+        Some(self.response(""))
+    }
+
+    fn response(&self, challenge: &str) -> String {
+        // We do not need a challenge in PLAIN authentication
+        let _ = challenge;
+        format!("{}{}{}{}{}", self.identity, NUL, self.username, NUL, self.password)
+    }
+}

src/client/mod.rs

@@ -33,6 +33,7 @@ use sendable_email::SendableEmail;
 pub mod server_info;
 pub mod connecter;
 pub mod stream;
+pub mod authentication;
 
 /// Represents the configuration of a client
 #[derive(Debug)]