Expose early keying material export

openssl-sys/src/openssl/v111.rs

@@ -89,4 +89,14 @@ extern "C" {
     pub fn SSL_get_max_early_data(ctx: *const ::SSL) -> u32;
     pub fn SSL_SESSION_set_max_early_data(ctx: *mut ::SSL_SESSION, max_early_data: u32) -> c_int;
     pub fn SSL_SESSION_get_max_early_data(ctx: *const ::SSL_SESSION) -> u32;
+
+    pub fn SSL_export_keying_material_early(
+        s: *mut ::SSL,
+        out: *mut c_uchar,
+        olen: size_t,
+        label: *const c_char,
+        llen: size_t,
+        context: *const c_uchar,
+        contextlen: size_t,
+    ) -> c_int;
 }

openssl/src/ssl/mod.rs

@@ -2498,6 +2498,33 @@ impl SslRef {
         }
     }
 
+    /// Derives keying material for application use in accordance to RFC 5705.
+    ///
+    /// Requires OpenSSL 1.1.1 or newer.
+    ///
+    /// This corresponds to [`SSL_export_keying_material_early`].
+    ///
+    /// [`SSL_export_keying_material_early`]: https://www.openssl.org/docs/manmaster/man3/SSL_export_keying_material_early.html
+    #[cfg(ossl111)]
+    pub fn export_keying_material_early(
+        &self,
+        out: &mut [u8],
+        label: &str,
+        context: &[u8],
+    ) -> Result<(), ErrorStack> {
+        unsafe {
+            cvt(ffi::SSL_export_keying_material_early(
+                self.as_ptr(),
+                out.as_mut_ptr() as *mut c_uchar,
+                out.len(),
+                label.as_ptr() as *const c_char,
+                label.len(),
+                context.as_ptr() as *const c_uchar,
+                context.len(),
+            )).map(|_| ())
+        }
+    }
+
     /// Sets the session to be used.
     ///
     /// This should be called before the handshake to attempt to reuse a previously established