Merge pull request #13 from nox/oxy-221

Bind the select_cert hook and allow users to inspect extensions early

boring/src/ssl/callbacks.rs

@@ -12,6 +12,7 @@ use std::sync::Arc;
 
 use error::ErrorStack;
 use ssl::AlpnError;
+use ssl::{ClientHello, SelectCertError};
 use ssl::{
     SniError, Ssl, SslAlert, SslContext, SslContextRef, SslRef, SslSession, SslSessionRef,
     SESSION_CTX_INDEX,
@@ -190,6 +191,25 @@ where
     }
 }
 
+pub unsafe extern "C" fn raw_select_cert<F>(
+    client_hello: *const ffi::SSL_CLIENT_HELLO,
+) -> ffi::ssl_select_cert_result_t
+where
+    F: Fn(&ClientHello) -> Result<(), SelectCertError> + Sync + Send + 'static,
+{
+    let ssl = SslRef::from_ptr_mut((*client_hello).ssl);
+    let client_hello = &*(client_hello as *const ClientHello);
+    let callback = ssl
+        .ssl_context()
+        .ex_data(SslContext::cached_ex_index::<F>())
+        .expect("BUG: select cert callback missing") as *const F;
+
+    match (*callback)(client_hello) {
+        Ok(()) => ffi::ssl_select_cert_result_t::ssl_select_cert_success,
+        Err(e) => e.0,
+    }
+}
+
 pub unsafe extern "C" fn raw_tlsext_status<F>(ssl: *mut ffi::SSL, _: *mut c_void) -> c_int
 where
     F: Fn(&mut SslRef) -> Result<bool, ErrorStack> + 'static + Sync + Send,

boring/src/ssl/mod.rs

@@ -463,6 +463,62 @@ impl AlpnError {
     pub const NOACK: AlpnError = AlpnError(ffi::SSL_TLSEXT_ERR_NOACK);
 }
 
+/// An error returned from a certificate selection callback.
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+pub struct SelectCertError(ffi::ssl_select_cert_result_t);
+
+impl SelectCertError {
+    /// A fatal error occured and the handshake should be terminated.
+    pub const ERROR: Self = Self(ffi::ssl_select_cert_result_t::ssl_select_cert_error);
+}
+
+/// Extension types, to be used with `ClientHello::get_extension`.
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+pub struct ExtensionType(u16);
+
+impl ExtensionType {
+    pub const SERVER_NAME: Self = Self(ffi::TLSEXT_TYPE_server_name as u16);
+    pub const STATUS_REQUEST: Self = Self(ffi::TLSEXT_TYPE_status_request as u16);
+    pub const EC_POINT_FORMATS: Self = Self(ffi::TLSEXT_TYPE_ec_point_formats as u16);
+    pub const SIGNATURE_ALGORITHMS: Self = Self(ffi::TLSEXT_TYPE_signature_algorithms as u16);
+    pub const SRTP: Self = Self(ffi::TLSEXT_TYPE_srtp as u16);
+    pub const APPLICATION_LAYER_PROTOCOL_NEGOTIATION: Self =
+        Self(ffi::TLSEXT_TYPE_application_layer_protocol_negotiation as u16);
+    pub const PADDING: Self = Self(ffi::TLSEXT_TYPE_padding as u16);
+    pub const EXTENDED_MASTER_SECRET: Self = Self(ffi::TLSEXT_TYPE_extended_master_secret as u16);
+    pub const TOKEN_BINDING: Self = Self(ffi::TLSEXT_TYPE_token_binding as u16);
+    pub const QUIC_TRANSPORT_PARAMETERS_LEGACY: Self =
+        Self(ffi::TLSEXT_TYPE_quic_transport_parameters_legacy as u16);
+    pub const QUIC_TRANSPORT_PARAMETERS_STANDARD: Self =
+        Self(ffi::TLSEXT_TYPE_quic_transport_parameters_standard as u16);
+    pub const CERT_COMPRESSION: Self = Self(ffi::TLSEXT_TYPE_cert_compression as u16);
+    pub const SESSION_TICKET: Self = Self(ffi::TLSEXT_TYPE_session_ticket as u16);
+    pub const SUPPORTED_GROUPS: Self = Self(ffi::TLSEXT_TYPE_supported_groups as u16);
+    pub const PRE_SHARED_KEY: Self = Self(ffi::TLSEXT_TYPE_pre_shared_key as u16);
+    pub const EARLY_DATA: Self = Self(ffi::TLSEXT_TYPE_early_data as u16);
+    pub const SUPPORTED_VERSIONS: Self = Self(ffi::TLSEXT_TYPE_supported_versions as u16);
+    pub const COOKIE: Self = Self(ffi::TLSEXT_TYPE_cookie as u16);
+    pub const PSK_KEY_EXCHANGE_MODES: Self = Self(ffi::TLSEXT_TYPE_psk_key_exchange_modes as u16);
+    pub const CERTIFICATE_AUTHORITIES: Self = Self(ffi::TLSEXT_TYPE_certificate_authorities as u16);
+    pub const SIGNATURE_ALGORITHMS_CERT: Self =
+        Self(ffi::TLSEXT_TYPE_signature_algorithms_cert as u16);
+    pub const KEY_SHARE: Self = Self(ffi::TLSEXT_TYPE_key_share as u16);
+    pub const RENEGOTIATE: Self = Self(ffi::TLSEXT_TYPE_renegotiate as u16);
+    pub const DELEGATED_CREDENTIAL: Self = Self(ffi::TLSEXT_TYPE_delegated_credential as u16);
+    pub const APPLICATION_SETTINGS: Self = Self(ffi::TLSEXT_TYPE_application_settings as u16);
+    pub const ENCRYPTED_CLIENT_HELLO: Self = Self(ffi::TLSEXT_TYPE_encrypted_client_hello as u16);
+    pub const ECH_IS_INNER: Self = Self(ffi::TLSEXT_TYPE_ech_is_inner as u16);
+    pub const CERTIFICATE_TIMESTAMP: Self = Self(ffi::TLSEXT_TYPE_certificate_timestamp as u16);
+    pub const NEXT_PROTO_NEG: Self = Self(ffi::TLSEXT_TYPE_next_proto_neg as u16);
+    pub const CHANNEL_ID: Self = Self(ffi::TLSEXT_TYPE_channel_id as u16);
+}
+
+impl From<u16> for ExtensionType {
+    fn from(value: u16) -> Self {
+        Self(value)
+    }
+}
+
 /// An SSL/TLS protocol version.
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
 pub struct SslVersion(u16);
@@ -1084,6 +1140,25 @@ impl SslContextBuilder {
             );
         }
     }
+    /// Sets a callback that is called before most ClientHello processing and before the decision whether
+    /// to resume a session is made. The callback may inspect the ClientHello and configure the
+    /// connection.
+    ///
+    /// This corresponds to [`SSL_CTX_set_select_certificate_cb`].
+    ///
+    /// [`SSL_CTX_set_select_certificate_cb`]: https://www.openssl.org/docs/man1.1.0/ssl/SSL_CTX_set_select_certificate_cb.html
+    pub fn set_select_certificate_callback<F>(&mut self, callback: F)
+    where
+        F: Fn(&ClientHello) -> Result<(), SelectCertError> + Sync + Send + 'static,
+    {
+        unsafe {
+            self.set_ex_data(SslContext::cached_ex_index::<F>(), callback);
+            ffi::SSL_CTX_set_select_certificate_cb(
+                self.as_ptr(),
+                Some(callbacks::raw_select_cert::<F>),
+            );
+        }
+    }
 
     /// Checks for consistency between the private key and certificate.
     ///
@@ -1560,6 +1635,29 @@ pub struct CipherBits {
     pub algorithm: i32,
 }
 
+#[repr(transparent)]
+pub struct ClientHello(ffi::SSL_CLIENT_HELLO);
+
+impl ClientHello {
+    /// Returns the data of a given extension, if present.
+    ///
+    /// This corresponds to [`SSL_early_callback_ctx_extension_get`].
+    ///
+    /// [`SSL_early_callback_ctx_extension_get`]: https://commondatastorage.googleapis.com/chromium-boringssl-docs/ssl.h.html#SSL_early_callback_ctx_extension_get
+    pub fn get_extension(&self, ext_type: ExtensionType) -> Option<&[u8]> {
+        unsafe {
+            let mut ptr = ptr::null();
+            let mut len = 0;
+            let result =
+                ffi::SSL_early_callback_ctx_extension_get(&self.0, ext_type.0, &mut ptr, &mut len);
+            if result == 0 {
+                return None;
+            }
+            Some(slice::from_raw_parts(ptr, len))
+        }
+    }
+}
+
 /// Information about a cipher.
 pub struct SslCipher(*mut ffi::SSL_CIPHER);
 

boring/src/ssl/test/mod.rs

@@ -25,9 +25,10 @@ use ssl;
 use ssl::test::server::Server;
 use ssl::SslVersion;
 use ssl::{
-    Error, HandshakeError, MidHandshakeSslStream, ShutdownResult, ShutdownState, Ssl, SslAcceptor,
-    SslAcceptorBuilder, SslConnector, SslContext, SslContextBuilder, SslFiletype, SslMethod,
-    SslOptions, SslSessionCacheMode, SslStream, SslStreamBuilder, SslVerifyMode, StatusType,
+    Error, ExtensionType, HandshakeError, MidHandshakeSslStream, ShutdownResult, ShutdownState,
+    Ssl, SslAcceptor, SslAcceptorBuilder, SslConnector, SslContext, SslContextBuilder, SslFiletype,
+    SslMethod, SslOptions, SslSessionCacheMode, SslStream, SslStreamBuilder, SslVerifyMode,
+    StatusType,
 };
 use x509::store::X509StoreBuilder;
 use x509::verify::X509CheckFlags;
@@ -480,6 +481,80 @@ fn test_alpn_server_unilateral() {
     assert_eq!(None, s.ssl().selected_alpn_protocol());
 }
 
+#[test]
+fn test_select_cert_ok() {
+    let mut server = Server::builder();
+    server
+        .ctx()
+        .set_select_certificate_callback(|_client_hello| Ok(()));
+    let server = server.build();
+
+    let client = server.client();
+    client.connect();
+}
+
+#[test]
+fn test_select_cert_error() {
+    let mut server = Server::builder();
+    server.should_error();
+    server
+        .ctx()
+        .set_select_certificate_callback(|_client_hello| Err(ssl::SelectCertError::ERROR));
+    let server = server.build();
+
+    let client = server.client();
+    client.connect_err();
+}
+
+#[test]
+fn test_select_cert_unknown_extension() {
+    let mut server = Server::builder();
+    let unknown_extension = std::sync::Arc::new(std::sync::Mutex::new(None));
+
+    server.ctx().set_select_certificate_callback({
+        let unknown = unknown_extension.clone();
+        move |client_hello| {
+            *unknown.lock().unwrap() = client_hello
+                .get_extension(ExtensionType::QUIC_TRANSPORT_PARAMETERS_LEGACY)
+                .map(ToOwned::to_owned);
+            Ok(())
+        }
+    });
+
+    let server = server.build();
+    let client = server.client();
+
+    client.connect();
+    assert_eq!(unknown_extension.lock().unwrap().as_deref(), None);
+}
+
+#[test]
+fn test_select_cert_alpn_extension() {
+    let mut server = Server::builder();
+    let alpn_extension = std::sync::Arc::new(std::sync::Mutex::new(None));
+    server.ctx().set_select_certificate_callback({
+        let alpn = alpn_extension.clone();
+        move |client_hello| {
+            *alpn.lock().unwrap() = Some(
+                client_hello
+                    .get_extension(ExtensionType::APPLICATION_LAYER_PROTOCOL_NEGOTIATION)
+                    .unwrap()
+                    .to_owned(),
+            );
+            Ok(())
+        }
+    });
+    let server = server.build();
+
+    let mut client = server.client();
+    client.ctx().set_alpn_protos(b"\x06http/2").unwrap();
+    client.connect();
+    assert_eq!(
+        alpn_extension.lock().unwrap().as_deref(),
+        Some(&b"\x00\x07\x06http/2"[..]),
+    );
+}
+
 #[test]
 #[should_panic(expected = "blammo")]
 fn write_panic() {