Adds support for linking against boringssl

The boringssl-sys crate is specific to the revision of boringssl you are
using, so you will need to generate it from a boringssl build tree and
point the openssl crate at it via cargo source replacement, or place the
build tree next to rust-openssl while building.

Co-authored-by: Matthew Maurer <mmaurer@google.com>

openssl-sys/Cargo.toml

@@ -15,9 +15,11 @@ build = "build/main.rs"
 
 [features]
 vendored = ['openssl-src']
+unstable_boringssl = ['bssl-sys']
 
 [dependencies]
 libc = "0.2"
+bssl-sys = { version = "0.1.0", optional = true }
 
 [build-dependencies]
 bindgen = { version = "0.59.2", optional = true }

openssl-sys/build/main.rs

@@ -60,9 +60,21 @@ fn find_openssl(target: &str) -> (Vec<PathBuf>, PathBuf) {
     find_normal::get_openssl(target)
 }
 
+fn check_ssl_kind() {
+    if cfg!(feature = "unstable_boringssl") {
+        println!("cargo:rustc-cfg=boringssl");
+        // BoringSSL does not have any build logic, exit early
+        std::process::exit(0);
+    } else {
+        println!("cargo:rustc-cfg=openssl");
+    }
+}
+
 fn main() {
     check_rustc_versions();
 
+    check_ssl_kind();
+
     let target = env::var("TARGET").unwrap();
 
     let (lib_dirs, include_dir) = find_openssl(&target);

openssl-sys/src/handwritten/mod.rs

@@ -1,35 +1,35 @@
-pub use handwritten::aes::*;
-pub use handwritten::asn1::*;
-pub use handwritten::bio::*;
-pub use handwritten::bn::*;
-pub use handwritten::cms::*;
-pub use handwritten::conf::*;
-pub use handwritten::crypto::*;
-pub use handwritten::dh::*;
-pub use handwritten::dsa::*;
-pub use handwritten::ec::*;
-pub use handwritten::err::*;
-pub use handwritten::evp::*;
-pub use handwritten::hmac::*;
-pub use handwritten::kdf::*;
-pub use handwritten::object::*;
-pub use handwritten::ocsp::*;
-pub use handwritten::pem::*;
-pub use handwritten::pkcs12::*;
-pub use handwritten::pkcs7::*;
-pub use handwritten::provider::*;
-pub use handwritten::rand::*;
-pub use handwritten::rsa::*;
-pub use handwritten::safestack::*;
-pub use handwritten::sha::*;
-pub use handwritten::srtp::*;
-pub use handwritten::ssl::*;
-pub use handwritten::stack::*;
-pub use handwritten::tls1::*;
-pub use handwritten::types::*;
-pub use handwritten::x509::*;
-pub use handwritten::x509_vfy::*;
-pub use handwritten::x509v3::*;
+pub use self::aes::*;
+pub use self::asn1::*;
+pub use self::bio::*;
+pub use self::bn::*;
+pub use self::cms::*;
+pub use self::conf::*;
+pub use self::crypto::*;
+pub use self::dh::*;
+pub use self::dsa::*;
+pub use self::ec::*;
+pub use self::err::*;
+pub use self::evp::*;
+pub use self::hmac::*;
+pub use self::kdf::*;
+pub use self::object::*;
+pub use self::ocsp::*;
+pub use self::pem::*;
+pub use self::pkcs12::*;
+pub use self::pkcs7::*;
+pub use self::provider::*;
+pub use self::rand::*;
+pub use self::rsa::*;
+pub use self::safestack::*;
+pub use self::sha::*;
+pub use self::srtp::*;
+pub use self::ssl::*;
+pub use self::stack::*;
+pub use self::tls1::*;
+pub use self::types::*;
+pub use self::x509::*;
+pub use self::x509_vfy::*;
+pub use self::x509v3::*;
 
 mod aes;
 mod asn1;