crypto: separate cipher/MAC availability check from information request

1 files changed, 18 insertions, 21 deletions

diff --git a/src/methods/generic_gcm/generic_gcm.c b/src/methods/generic_gcm/generic_gcm.c
index 9481100..2a7987c 100644
--- a/src/methods/generic_gcm/generic_gcm.c
+++ b/src/methods/generic_gcm/generic_gcm.c
@@ -43,8 +43,8 @@ struct fastd_method_session_state {
 };
 
 
-static bool cipher_get(fastd_context_t *ctx, const char *name, const fastd_cipher_info_t **cipher_info, const fastd_cipher_t **cipher, const fastd_cipher_context_t **cctx) {
-	if (!fastd_mac_info_get_by_name("ghash"))
+static bool cipher_get(fastd_context_t *ctx, const char *name, const fastd_cipher_info_t **cipher_info, const fastd_cipher_t **cipher, const fastd_cipher_context_t **cctx, bool check) {
+	if (check && !fastd_mac_is_available("ghash"))
 		return false;
 
 	size_t len = strlen(name);
@@ -59,36 +59,33 @@ static bool cipher_get(fastd_context_t *ctx, const char *name, const fastd_ciphe
 	memcpy(name_ctr, name, len-3);
 	strncpy(name_ctr+len-3, "ctr", 4);
 
-	const fastd_cipher_info_t *info = NULL;
-
-	if (ctx) {
-		*cipher = fastd_cipher_get_by_name(ctx, name_ctr, &info, cctx);
-		if (!*cipher)
-			return false;
-	}
-	else {
-		info = fastd_cipher_info_get_by_name(name_ctr);
-		if (!info)
-			return false;
-	}
-
-	if (info->iv_length <= COMMON_NONCEBYTES)
+	if (check && !fastd_cipher_is_available(name_ctr))
 		return false;
 
-	if (cipher_info)
-		*cipher_info = info;
+	if (ctx)
+		*cipher = fastd_cipher_get_by_name(ctx, name_ctr, cipher_info, cctx);
+	else if (cipher_info)
+		*cipher_info = fastd_cipher_info_get_by_name(name_ctr);
 
 	return true;
 }
 
 
 static bool method_provides(const char *name) {
-	return cipher_get(NULL, name, NULL, NULL, NULL);
+	const fastd_cipher_info_t *cipher_info;
+
+	if (!cipher_get(NULL, name, &cipher_info, NULL, NULL, true))
+		return false;
+
+	if (cipher_info->iv_length <= COMMON_NONCEBYTES)
+		return false;
+
+	return true;
 }
 
 static size_t method_key_length(fastd_context_t *ctx, const char *name) {
 	const fastd_cipher_info_t *cipher_info;
-	if (!cipher_get(NULL, name, &cipher_info, NULL, NULL))
+	if (!cipher_get(NULL, name, &cipher_info, NULL, NULL, false))
 		exit_bug(ctx, "generic-gcm: can't get cipher key length");
 
 	return cipher_info->key_length;
@@ -99,7 +96,7 @@ static fastd_method_session_state_t* method_session_init(fastd_context_t *ctx, c
 
 	fastd_method_common_init(ctx, &session->common, initiator);
 
-	if (!cipher_get(ctx, name, &session->cipher_info, &session->cipher, &session->cipher_ctx))
+	if (!cipher_get(ctx, name, &session->cipher_info, &session->cipher, &session->cipher_ctx, false))
 		exit_bug(ctx, "generic-gcm: can't instanciate cipher");
 
 	session->cipher_state = session->cipher->init_state(ctx, session->cipher_ctx, secret);