Merge #183: Default to ring if multiple rustls features are set

80bf744 test: don't assert the value returned by `relay_fee` (valued mammal)
0e28021 Check in CI that we compile if all `rustls` features are set (Elias Rohrer)
980fa4a Default to `ring` if multiple `rustls` features are set (Elias Rohrer)

Pull request description:

  Fixes #181

  We default to use `ring` if multiple features are set, ensuring the features are additive. To that end, we also add a check to CI that asserts we succeed to build with both features set.

  Would be cool to get a patch release for this, as it's currently breaking our docs.rs builds in `lightning-liquidity`.

ACKs for top commit:
  ValuedMammal:
    ACK 80bf744.
  oleonardolima:
    cACK 80bf744

Tree-SHA512: 0b1bacb0f3a57fd8c666e1ece14b9a733f9d5dfdec7efd6461b400d58ef0e302c286597531381e417b5fdf1b97659ed36266d2cf89f8a0c4cab5e4d9b3fdeed7

Author: ValuedMammal

.github/workflows/cont_integration.yml

@@ -41,6 +41,7 @@ jobs:
       - run: cargo check --verbose --no-default-features --features=proxy,use-openssl
       - run: cargo check --verbose --no-default-features --features=proxy,use-rustls
       - run: cargo check --verbose --no-default-features --features=proxy,use-rustls-ring
+      - run: cargo check --verbose --no-default-features --features=proxy,use-rustls,use-rustls-ring
 
   fmt:
     name: Rust fmt

src/raw_client.rs

@@ -408,7 +408,7 @@ impl RawClient<ElectrumSslStream> {
 
         if rustls::crypto::CryptoProvider::get_default().is_none() {
             // We install a crypto provider depending on the set feature.
-            #[cfg(feature = "use-rustls")]
+            #[cfg(all(feature = "use-rustls", not(feature = "use-rustls-ring")))]
             rustls::crypto::CryptoProvider::install_default(
                 rustls::crypto::aws_lc_rs::default_provider(),
             )
@@ -449,7 +449,7 @@ impl RawClient<ElectrumSslStream> {
             builder
                 .dangerous()
                 .with_custom_certificate_verifier(std::sync::Arc::new(
-                    #[cfg(feature = "use-rustls")]
+                    #[cfg(all(feature = "use-rustls", not(feature = "use-rustls-ring")))]
                     danger::NoCertificateVerification::new(rustls::crypto::aws_lc_rs::default_provider()),
                     #[cfg(feature = "use-rustls-ring")]
                     danger::NoCertificateVerification::new(rustls::crypto::ring::default_provider()),
@@ -1249,7 +1249,7 @@ mod test {
         let client = RawClient::new(get_test_server(), None).unwrap();
 
         let resp = client.relay_fee().unwrap();
-        assert_eq!(resp, 0.00001);
+        assert!(resp > 0.0);
     }
 
     #[test]