Remove rustls-native-roots dependency (#110)

There are some issues integrating with trust stores: rustls/rustls-native-certs#16,
and also some issues with regards to what gets run in forked processes:
kornelski/rust-security-framework#136.

Cargo.toml

@@ -11,7 +11,6 @@ links = "crustls"
 rustls = { version = "^0.19.0", features = [ "dangerous_configuration" ] }
 webpki = "0.21"
 libc = "0.2"
-rustls-native-certs = "0.5.0"
 sct = "0.6.0"
 rustls-pemfile = "0.2.0"
 log = "0.4.14"

src/client.rs

@@ -30,7 +30,7 @@ use crate::{
 };
 
 /// A client config being constructed. A builder can be modified by,
-/// e.g. rustls_client_config_builder_load_native_roots. Once you're
+/// e.g. rustls_client_config_builder_load_roots_from_file. Once you're
 /// done configuring settings, call rustls_client_config_builder_build
 /// to turn it into a *rustls_client_config. This object is not safe
 /// for concurrent mutation. Under the hood, it corresponds to a
@@ -64,8 +64,8 @@ impl CastPtr for rustls_client_config {
 /// Create a rustls_client_config_builder. Caller owns the memory and must
 /// eventually call rustls_client_config_builder_build, then free the
 /// resulting rustls_client_config. This starts out with no trusted roots.
-/// Caller must add roots with rustls_client_config_builder_load_native_roots
-/// or rustls_client_config_builder_load_roots_from_file.
+/// Caller must add roots with rustls_client_config_builder_load_roots_from_file
+/// or provide a custom verifier.
 #[no_mangle]
 pub extern "C" fn rustls_client_config_builder_new() -> *mut rustls_client_config_builder {
     ffi_panic_boundary! {
@@ -252,23 +252,6 @@ pub extern "C" fn rustls_client_config_builder_dangerous_set_certificate_verifie
     }
 }
 
-/// Add certificates from platform's native root store, using
-/// https://github.com/ctz/rustls-native-certs#readme.
-#[no_mangle]
-pub extern "C" fn rustls_client_config_builder_load_native_roots(
-    config: *mut rustls_client_config_builder,
-) -> rustls_result {
-    ffi_panic_boundary! {
-        let mut config: &mut ClientConfig = try_mut_from_ptr!(config);
-        let store = match rustls_native_certs::load_native_certs() {
-            Ok(store) => store,
-            Err(_) => return rustls_result::Io,
-        };
-        config.root_store = store;
-        rustls_result::Ok
-    }
-}
-
 /// Use the trusted root certificates from the provided store.
 ///
 /// This replaces any trusted roots already configured with copies

src/crustls.h

@@ -147,7 +147,7 @@ typedef struct rustls_client_config rustls_client_config;
 
 /**
  * A client config being constructed. A builder can be modified by,
- * e.g. rustls_client_config_builder_load_native_roots. Once you're
+ * e.g. rustls_client_config_builder_load_roots_from_file. Once you're
  * done configuring settings, call rustls_client_config_builder_build
  * to turn it into a *rustls_client_config. This object is not safe
  * for concurrent mutation. Under the hood, it corresponds to a
@@ -375,7 +375,7 @@ typedef rustls_io_result (*rustls_read_callback)(void *userdata, uint8_t *buf, s
  * the implementation should return a nonzero rustls_io_result, which will be
  * passed through to the caller. On POSIX systems, returning `errno` is convenient.
  * On other systems, any appropriate error code works.
- * It's best to make one write attempt to the network per call. Additional write will
+ * It's best to make one write attempt to the network per call. Additional writes will
  * be triggered by subsequent calls to one of the `_write_tls` methods.
  * `userdata` is set to the value provided to `rustls_*_session_set_userdata`. In most
  * cases that should be a struct that contains, at a minimum, a file descriptor.
@@ -626,8 +626,8 @@ void rustls_client_cert_verifier_optional_free(const struct rustls_client_cert_v
  * Create a rustls_client_config_builder. Caller owns the memory and must
  * eventually call rustls_client_config_builder_build, then free the
  * resulting rustls_client_config. This starts out with no trusted roots.
- * Caller must add roots with rustls_client_config_builder_load_native_roots
- * or rustls_client_config_builder_load_roots_from_file.
+ * Caller must add roots with rustls_client_config_builder_load_roots_from_file
+ * or provide a custom verifier.
  */
 struct rustls_client_config_builder *rustls_client_config_builder_new(void);
 
@@ -681,12 +681,6 @@ const struct rustls_client_config *rustls_client_config_builder_build(struct rus
 void rustls_client_config_builder_dangerous_set_certificate_verifier(struct rustls_client_config_builder *config,
                                                                      rustls_verify_server_cert_callback callback);
 
-/**
- * Add certificates from platform's native root store, using
- * https://github.com/ctz/rustls-native-certs#readme.
- */
-enum rustls_result rustls_client_config_builder_load_native_roots(struct rustls_client_config_builder *config);
-
 /**
  * Use the trusted root certificates from the provided store.
  *