Better gating of alloc (#62)

Gate all `alloc` usage with feature `alloc` instead of not std.

Update CI to check `alloc` feature only build & test.

Resolves #36.

Author: Taowyoo

.github/workflows/rustls-rustcrypto.yml

@@ -30,6 +30,8 @@ jobs:
         with:
           toolchain: ${{ matrix.toolchain }}
       - run: cargo build
+      - name: Test no_std with alloc build
+        run: cargo build --no-default-features --features tls12,alloc
 
   clippy:
     runs-on: ubuntu-latest
@@ -74,3 +76,5 @@ jobs:
         with:
           toolchain: ${{ matrix.toolchain }}
       - run: cargo test --features tls12
+      - name: Test no_std with alloc
+        run: cargo test --no-default-features --features tls12,alloc

README.md

@@ -2,20 +2,21 @@
 
 WIP RustCrypto-based provider implementation for version 0.23 of [rustls](https://github.com/rustls/rustls/pull/1405).
 
-Some code comes directly from one of main rustls contributor, [@ctz](https://github.com/ctz). 
+Some code comes directly from one of main rustls contributor, [@ctz](https://github.com/ctz).
 
 Some part of this code is directly derived from his work but modified to use generic instead.
 
 ## ⚠️USE THIS AT YOUR OWN RISK! DO NOT USE THIS IN PRODUCTION⚠️
 
-Not only that this is incomplete that only few selected TLS suites implemented (it should be well enough to cover 70% of the usage), but the elephant in the room is that neither did rustls nor RustCrypto packages were formally verified and certified with FIPS compliance. 
+Not only that this is incomplete that only few selected TLS suites implemented (it should be well enough to cover 70% of the usage), but the elephant in the room is that neither did rustls nor RustCrypto packages were formally verified and certified with FIPS compliance.
 
 Note that RustCrypto performance is generally inferior than ring, but in exchange you got a pure Rust implementation that theoretically compiles everywhere Rust was ported to. In our case, we need to have `std` but foundational support for future `no_std` expansion is already here.
 
-This package is still in its very early phase, so until we think the code is okay for general public use, this won't be published to crates.io anytime soon. 
+This package is still in its very early phase, so until we think the code is okay for general public use, this won't be published to crates.io anytime soon.
 
 Meanwhile you can try it out using git crate installation:
-```
+
+```toml
 rustls-rustcrypto = { git = "https://github.com/RustCrypto/rustls-rustcrypto", version = "0.1" }
 ```
 
@@ -33,14 +34,14 @@ rustls-rustcrypto = { git = "https://github.com/RustCrypto/rustls-rustcrypto", v
 
 ## QUIC Support
 
-There won't be QUIC support anytime soon until https://github.com/rustls/rustls/issues/1491 is solved. HTTP/2 however should work out of the box.
+There won't be QUIC support anytime soon until <https://github.com/rustls/rustls/issues/1491> is solved. HTTP/2 however should work out of the box.
 
 ## License
 
 Licensed under either of:
 
- * [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0)
- * [MIT license](http://opensource.org/licenses/MIT)
+- [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0)
+- [MIT license](http://opensource.org/licenses/MIT)
 
 at your option.
 

src/aead/chacha20.rs

@@ -1,4 +1,4 @@
-#[cfg(not(feature = "std"))]
+#[cfg(feature = "alloc")]
 use alloc::boxed::Box;
 
 use super::{DecryptBufferAdapter, EncryptBufferAdapter};

src/aead/gcm.rs

@@ -1,4 +1,4 @@
-#[cfg(not(feature = "std"))]
+#[cfg(feature = "alloc")]
 use alloc::boxed::Box;
 
 use super::{DecryptBufferAdapter, EncryptBufferAdapter};

src/hash.rs

@@ -1,4 +1,4 @@
-#[cfg(not(feature = "std"))]
+#[cfg(feature = "alloc")]
 use alloc::boxed::Box;
 
 use digest::{Digest, OutputSizeUser};

src/hmac.rs

@@ -1,4 +1,4 @@
-#[cfg(not(feature = "std"))]
+#[cfg(feature = "alloc")]
 use alloc::boxed::Box;
 
 use crypto_common::OutputSizeUser;

src/kx.rs

@@ -1,4 +1,4 @@
-#[cfg(not(feature = "std"))]
+#[cfg(feature = "alloc")]
 use alloc::boxed::Box;
 
 use crypto::{SharedSecret, SupportedKxGroup};

src/lib.rs

@@ -7,8 +7,13 @@
 )]
 #![cfg_attr(not(feature = "std"), no_std)]
 
+#[cfg(not(feature = "alloc"))]
+compile_error!("Rustls currently does not support alloc-less environments");
+
+#[cfg(feature = "alloc")]
 extern crate alloc;
 
+#[cfg(feature = "alloc")]
 use alloc::sync::Arc;
 
 use rustls::crypto::{

src/quic.rs

@@ -1,6 +1,6 @@
 #![allow(clippy::duplicate_mod)]
 
-#[cfg(not(feature = "std"))]
+#[cfg(feature = "alloc")]
 use alloc::boxed::Box;
 
 use aead::AeadCore;

src/sign.rs

@@ -1,6 +1,5 @@
-use alloc::sync::Arc;
-#[cfg(not(feature = "std"))]
-use alloc::vec::Vec;
+#[cfg(feature = "alloc")]
+use alloc::{sync::Arc, vec::Vec};
 use core::marker::PhantomData;
 
 use self::ecdsa::{EcdsaSigningKeyP256, EcdsaSigningKeyP384};