psk: Add basic support for RFC 9258 external PSK importer interface

This adds a minimal, callback-based API to import external PSK,
following RFC 9258.  The client and the server importing external PSK
are supposed to set a callback to retrieve PSK, which returns flags
that may indicate the PSK is imported, along with the key:

  typedef int gnutls_psk_client_credentials_function3(
          gnutls_session_t session,
          gnutls_datum_t *username, gnutls_datum_t *key,
          gnutls_psk_key_flags *flags);

  typedef int gnutls_psk_server_credentials_function3(
          gnutls_session_t session,
          const gnutls_datum_t *username, gnutls_datum_t *key,
          gnutls_psk_key_flags *flags);

Those callbacks are responsible to call
gnutls_psk_format_imported_identity() for external PSKs to build a
serialized PSK identity, and set GNUTLS_PSK_KEY_EXT in flags if the
identity is an imported one.

Signed-off-by: Daiki Ueno <ueno@gnu.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/lib/auth/psk.c b/lib/auth/psk.c
index 17206f69c5..8ddb239823 100644
--- a/lib/auth/psk.c
+++ b/lib/auth/psk.c
@@ -136,7 +136,7 @@ int _gnutls_gen_psk_client_kx(gnutls_session_t session, gnutls_buffer_st *data)
 		return GNUTLS_E_INTERNAL_ERROR;
 	}
 
-	ret = _gnutls_find_psk_key(session, cred, &username, &key, &free);
+	ret = _gnutls_find_psk_key(session, cred, &username, &key, NULL, &free);
 	if (ret < 0)
 		return gnutls_assert_val(ret);
 
@@ -224,7 +224,7 @@ static int _gnutls_proc_psk_client_kx(gnutls_session_t session, uint8_t *data,
 		return gnutls_assert_val(ret);
 
 	ret = _gnutls_psk_pwd_find_entry(session, info->username,
-					 info->username_len, &psk_key);
+					 info->username_len, &psk_key, NULL);
 	if (ret < 0)
 		return gnutls_assert_val(ret);