ffi: expose client-side session resumption and 0-RTT API

Motivation:

Quiche added support for session resumption and 0-RTT lately but the API was not exposed via the C api.

This was done in https://github.com/cloudflare/quiche/pull/911 and https://github.com/cloudflare/quiche/pull/914.

Modifications:

Add C API to also be able to make use of the functionality via C.

Result:

Be able to use session resumption and 0-RTT via the C api

2 files changed, 33 insertions, 0 deletions

diff --git a/include/quiche.h b/include/quiche.h
index a49f37a1..e8c46b58 100644
--- a/include/quiche.h
+++ b/include/quiche.h
@@ -256,6 +256,9 @@ bool quiche_conn_set_qlog_path(quiche_conn *conn, const char *path,
 void quiche_conn_set_qlog_fd(quiche_conn *conn, int fd, const char *log_title,
                              const char *log_desc);
 
+// Configures the given session for resumption.
+int quiche_conn_set_session(quiche_conn *conn, const uint8_t *buf, size_t buf_len);
+
 // Processes QUIC packets received from the peer.
 ssize_t quiche_conn_recv(quiche_conn *conn, uint8_t *buf, size_t buf_len);
 
@@ -321,6 +324,9 @@ void quiche_conn_trace_id(quiche_conn *conn, const uint8_t **out, size_t *out_le
 void quiche_conn_application_proto(quiche_conn *conn, const uint8_t **out,
                                    size_t *out_len);
 
+// Returns the serialized cryptographic session for the connection.
+void quiche_conn_session(quiche_conn *conn, const uint8_t **out, size_t *out_len);
+
 // Returns true if the connection handshake is complete.
 bool quiche_conn_is_established(quiche_conn *conn);
 
diff --git a/src/ffi.rs b/src/ffi.rs
index 96b1dd08..1db9d05d 100644
--- a/src/ffi.rs
+++ b/src/ffi.rs
@@ -540,6 +540,19 @@ pub extern fn quiche_conn_set_qlog_fd(
 }
 
 #[no_mangle]
+pub extern fn quiche_conn_set_session(
+    conn: &mut Connection, buf: *const u8, buf_len: size_t,
+) -> c_int {
+    let buf = unsafe { slice::from_raw_parts(buf, buf_len) };
+
+    match conn.set_session(buf) {
+        Ok(_) => 0,
+
+        Err(e) => e.to_c() as c_int,
+    }
+}
+
+#[no_mangle]
 pub extern fn quiche_conn_recv(
     conn: &mut Connection, buf: *mut u8, buf_len: size_t,
 ) -> ssize_t {
@@ -764,6 +777,20 @@ pub extern fn quiche_conn_application_proto(
 }
 
 #[no_mangle]
+pub extern fn quiche_conn_session(
+    conn: &mut Connection, out: &mut *const u8, out_len: &mut size_t,
+) {
+    match conn.session() {
+        Some(session) => {
+            *out = session.as_ptr();
+            *out_len = session.len();
+        },
+
+        None => *out_len = 0,
+    }
+}
+
+#[no_mangle]
 pub extern fn quiche_conn_is_established(conn: &mut Connection) -> bool {
     conn.is_established()
 }