isolate scram behind a compilation feature

sasl/Cargo.toml

@@ -13,6 +13,13 @@ license = "LGPL-3.0+"
 [badges]
 gitlab = { repository = "lumi/sasl-rs" }
 
+[features]
+default = ["scram"]
+scram = ["openssl"]
+
 [dependencies]
-openssl = "0.9.7"
 base64 = "0.4.0"
+
+[dependencies.openssl]
+version = "0.9.7"
+optional = true

sasl/src/client/mechanisms/mod.rs

@@ -2,8 +2,12 @@
 
 mod anonymous;
 mod plain;
+
+#[cfg(feature = "scram")]
 mod scram;
 
 pub use self::anonymous::Anonymous;
 pub use self::plain::Plain;
+
+#[cfg(feature = "scram")]
 pub use self::scram::Scram;

sasl/src/common/mod.rs

@@ -4,6 +4,7 @@ use std::convert::From;
 
 use std::string::FromUtf8Error;
 
+#[cfg(feature = "scram")]
 pub mod scram;
 
 #[derive(Clone, Debug, PartialEq, Eq)]

sasl/src/error.rs

@@ -1,14 +1,17 @@
+#[cfg(feature = "scram")]
 use openssl::error::ErrorStack;
 
 /// A wrapper enum for things that could go wrong in this crate.
 #[derive(Debug)]
 pub enum Error {
+    #[cfg(feature = "scram")]
     /// An error in OpenSSL.
     OpenSslErrorStack(ErrorStack),
     /// An error in a SASL mechanism.
     SaslError(String),
 }
 
+#[cfg(feature = "scram")]
 impl From<ErrorStack> for Error {
     fn from(err: ErrorStack) -> Error {
         Error::OpenSslErrorStack(err)

sasl/src/lib.rs

@@ -124,6 +124,8 @@
 //! ```
 
 extern crate base64;
+
+#[cfg(feature = "scram")]
 extern crate openssl;
 
 mod error;

sasl/src/server/mod.rs

@@ -1,8 +1,12 @@
-use common::scram::ScramProvider;
 use common::{Credentials, Identity};
 
+#[cfg(feature = "scram")]
+use common::scram::ScramProvider;
+
 pub trait Validator {
     fn validate_credentials(&self, credentials: &Credentials) -> Result<Identity, String>;
+
+    #[cfg(feature = "scram")]
     fn request_pbkdf2<S: ScramProvider>(&self) -> Result<(Vec<u8>, usize, Vec<u8>), String>;
 }
 
@@ -63,6 +67,7 @@ pub mod mechanisms {
         }
     }
 
+    #[cfg(feature = "scram")]
     mod scram {
         use std::marker::PhantomData;
 
@@ -235,5 +240,6 @@ pub mod mechanisms {
     }
 
     pub use self::plain::Plain;
+    #[cfg(feature = "scram")]
     pub use self::scram::Scram;
 }