Add an authentication trait

src/authentication.rs

@@ -0,0 +1,101 @@
+// 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.
+
+//! Provides authentication mecanisms
+
+use serialize::base64::{self, ToBase64, FromBase64};
+use serialize::hex::ToHex;
+use crypto::hmac::Hmac;
+use crypto::md5::Md5;
+use crypto::mac::Mac;
+
+use NUL;
+use error::Error;
+use extension::Extension;
+
+/// Represents an authentication mecanism
+pub trait Mecanism {
+    /// Returns the matching `Extension`
+    fn extension() -> Extension;
+    /// Returns the initial response support
+    fn supports_initial_response() -> bool;
+    /// Returns the response
+    fn response(username: &str, password: &str, challenge: Option<&str>) -> Result<String, Error>;
+}
+
+/// PLAIN authentication mecanism
+/// RFC 4616: https://tools.ietf.org/html/rfc4616
+#[derive(Copy,Clone)]
+pub struct Plain;
+
+impl Mecanism for Plain {
+    fn extension() -> Extension {
+        Extension::PlainAuthentication
+    }
+
+    fn supports_initial_response() -> bool {
+        true
+    }
+
+    fn response(username: &str, password: &str, challenge: Option<&str>) -> Result<String, Error> {
+        match challenge {
+            Some(_) => Err(Error::ClientError("This mecanism does not expect a challenge")),
+            None => Ok(format!("{}{}{}{}", NUL, username, NUL, password).as_bytes().to_base64(base64::STANDARD)),
+        }
+    }
+}
+
+/// CRAM-MD5 authentication mecanism
+/// RFC 2195: https://tools.ietf.org/html/rfc2195
+#[derive(Copy,Clone)]
+pub struct CramMd5;
+
+impl Mecanism for CramMd5 {
+    fn extension() -> Extension {
+        Extension::CramMd5Authentication
+    }
+
+    fn supports_initial_response() -> bool {
+        false
+    }
+
+    fn response(username: &str, password: &str, challenge: Option<&str>) -> Result<String, Error> {
+        let encoded_challenge = match challenge {
+            Some(challenge) => challenge,
+            None => return Err(Error::ClientError("This mecanism does expect a challenge")),
+        };
+
+        let decoded_challenge = match encoded_challenge.from_base64() {
+            Ok(challenge) => challenge,
+            Err(error) => return Err(Error::ChallengeParsingError(error)),
+        };
+
+        let mut hmac = Hmac::new(Md5::new(), password.as_bytes());
+        hmac.input(&decoded_challenge);
+
+        Ok(format!("{} {}", username, hmac.result().code().to_hex()).as_bytes().to_base64(base64::STANDARD))
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::{Mecanism, Plain, CramMd5};
+
+    #[test]
+    fn test_plain() {
+        assert_eq!(Plain::response("username", "password", None).unwrap(), "AHVzZXJuYW1lAHBhc3N3b3Jk");
+    }
+
+    #[test]
+    fn test_cram_md5() {
+        assert_eq!(CramMd5::response("alice", "wonderland",
+            Some("PDE3ODkzLjEzMjA2NzkxMjNAdGVzc2VyYWN0LnN1c2FtLmluPg==")).unwrap(),
+            "YWxpY2UgNjRiMmE0M2MxZjZlZDY4MDZhOTgwOTE0ZTIzZTc1ZjA=");
+    }
+}

src/client/authentication.rs

@@ -1,54 +0,0 @@
-// 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.
-
-//! Provides authentication functions
-
-use serialize::base64::{self, ToBase64, FromBase64};
-use serialize::hex::ToHex;
-use crypto::hmac::Hmac;
-use crypto::md5::Md5;
-use crypto::mac::Mac;
-
-use NUL;
-use error::Error;
-
-/// Returns a PLAIN mecanism response
-pub fn plain(username: &str, password: &str) -> String {
-    format!("{}{}{}{}", NUL, username, NUL, password).as_bytes().to_base64(base64::STANDARD)
-}
-
-/// Returns a CRAM-MD5 mecanism response
-pub fn cram_md5(username: &str, password: &str, encoded_challenge: &str) -> Result<String, Error> {
-    let challenge = match encoded_challenge.from_base64() {
-        Ok(challenge) => challenge,
-        Err(error) => return Err(Error::ChallengeParsingError(error)),
-    };
-
-    let mut hmac = Hmac::new(Md5::new(), password.as_bytes());
-    hmac.input(&challenge);
-
-    Ok(format!("{} {}", username, hmac.result().code().to_hex()).as_bytes().to_base64(base64::STANDARD))
-}
-
-#[cfg(test)]
-mod test {
-    use super::{plain, cram_md5};
-
-    #[test]
-    fn test_plain() {
-        assert_eq!(plain("username", "password"), "AHVzZXJuYW1lAHBhc3N3b3Jk");
-    }
-
-    #[test]
-    fn test_cram_md5() {
-        assert_eq!(cram_md5("alice", "wonderland",
-            "PDE3ODkzLjEzMjA2NzkxMjNAdGVzc2VyYWN0LnN1c2FtLmluPg==").unwrap(),
-            "YWxpY2UgNjRiMmE0M2MxZjZlZDY4MDZhOTgwOTE0ZTIzZTc1ZjA=");
-    }
-}

src/client/mod.rs

@@ -16,13 +16,12 @@ use std::io::{BufRead, Read, Write};
 use bufstream::BufStream;
 
 use response::ResponseParser;
+use authentication::{Mecanism, CramMd5, Plain};
 use error::{Error, SmtpResult};
 use client::net::{Connector, SmtpStream};
-use client::authentication::{plain, cram_md5};
 use {CRLF, MESSAGE_ENDING};
 
 pub mod net;
-mod authentication;
 
 /// Returns the string after adding a dot at the beginning of each line starting with a dot
 ///
@@ -170,7 +169,7 @@ impl<S: Connector + Write + Read = SmtpStream> Client<S> {
 
     /// Sends an AUTH command with PLAIN mecanism
     pub fn auth_plain(&mut self, username: &str, password: &str) -> SmtpResult {
-        self.command(&format!("AUTH PLAIN {}", plain(username, password)))
+        self.command(&format!("AUTH PLAIN {}", try!(Plain::response(username, password, None))))
     }
 
     /// Sends an AUTH command with CRAM-MD5 mecanism
@@ -180,7 +179,7 @@ impl<S: Connector + Write + Read = SmtpStream> Client<S> {
             None => return Err(Error::ResponseParsingError("Could not read CRAM challenge")),
         };
 
-        let cram_response = try!(cram_md5(username, password, &encoded_challenge));
+        let cram_response = try!(CramMd5::response(username, password, Some(&encoded_challenge)));
 
         self.command(&format!("AUTH CRAM-MD5 {}", cram_response))
     }

src/lib.rs

@@ -155,6 +155,7 @@ pub mod response;
 pub mod error;
 pub mod sendable_email;
 pub mod email;
+pub mod authentication;
 
 // Registrated port numbers:
 // https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml