fips feature flag

quic/s2n-quic-tls-default/Cargo.toml

@@ -10,6 +10,22 @@ license = "Apache-2.0"
 # Exclude corpus files when publishing to crates.io
 exclude = ["corpus.tar.gz"]
 
+[features]
+# The [`?`](https://doc.rust-lang.org/cargo/reference/features.html?highlight=addative#dependency-features)
+# syntax only enable `fips` for `s2n-quic-tls` if something else enables `s2n-quic-tls`. This
+# preserves the selective compilation of the two tls crates.
+fips = ["s2n-quic-tls?/fips"]
+
+# Declare `s2n-quic-tls` as an optional dependency since the `?` syntax for features requires
+# the dependency be optional.
+#
+# It is not possible to enable a feature flag based on target since Cargo currently doesn't
+# support platform specific feature flags: https://github.com/rust-lang/cargo/issues/1197. In
+# order to support the `?` syntax, we declare s2n-quic-tls as an optional dependency.
+# `s2n-quic-tls` only gets enabled based on the target.
+[dependencies]
+s2n-quic-tls = { path = "../s2n-quic-tls", optional = true }
+
 [target.'cfg(unix)'.dependencies]
 s2n-quic-tls = { version = "=0.37.0", path = "../s2n-quic-tls" }
 

quic/s2n-quic-tls/Cargo.toml

@@ -11,6 +11,7 @@ license = "Apache-2.0"
 exclude = ["corpus.tar.gz"]
 
 [features]
+fips = ["s2n-quic-crypto/fips"]
 unstable_client_hello = []
 unstable_private_key = []
 

quic/s2n-quic/Cargo.toml

@@ -15,7 +15,10 @@ default = [
     "provider-address-token-default",
     "provider-tls-default",
 ]
-provider-crypto-fips = ["s2n-quic-crypto/fips"]
+provider-crypto-fips = [
+    "s2n-quic-tls-default?/fips",
+    "s2n-quic-tls?/fips",
+]
 provider-address-token-default = [
     "cuckoofilter",
     "hash_hasher",