crypto/hash-gnutls: Implement new hash API

Implements the new hashing API in the gnutls hash driver.
Supports creating/destroying a context, updating the context
with input data and obtaining an output hash.

Signed-off-by: Alejandro Zeise <alejandro.zeise@seagate.com>
[ clg: - Dropped qcrypto_hash_supports() in qcrypto_gnutls_hash_new()
       - Reworked qcrypto_gnutls_hash_finalize()
       - Handled gnutls_hash_init() errors in qcrypto_gnutls_hash_new()
       - Replaced gnutls_hash_deinit() by gnutls_hash_output() in
         qcrypto_gnutls_hash_finalize()
       - Freed resources with gnutls_hash_deinit() in
         qcrypto_gnutls_hash_free() ]
Signed-off-by: Cédric Le Goater <clg@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

crypto/hash-gnutls.c

@@ -1,6 +1,7 @@
 /*
  * QEMU Crypto hash algorithms
  *
+ * Copyright (c) 2024 Seagate Technology LLC and/or its Affiliates
  * Copyright (c) 2021 Red Hat, Inc.
  *
  * This library is free software; you can redistribute it and/or
@@ -98,7 +99,84 @@ qcrypto_gnutls_hash_bytesv(QCryptoHashAlgo alg,
     return 0;
 }
 
+static
+QCryptoHash *qcrypto_gnutls_hash_new(QCryptoHashAlgo alg, Error **errp)
+{
+    QCryptoHash *hash;
+    int ret;
+
+    hash = g_new(QCryptoHash, 1);
+    hash->alg = alg;
+    hash->opaque = g_new(gnutls_hash_hd_t, 1);
+
+    ret = gnutls_hash_init(hash->opaque, qcrypto_hash_alg_map[alg]);
+    if (ret < 0) {
+        error_setg(errp,
+                   "Unable to initialize hash algorithm: %s",
+                   gnutls_strerror(ret));
+        g_free(hash->opaque);
+        g_free(hash);
+        return NULL;
+    }
+
+    return hash;
+}
+
+static
+void qcrypto_gnutls_hash_free(QCryptoHash *hash)
+{
+    gnutls_hash_hd_t *ctx = hash->opaque;
+
+    gnutls_hash_deinit(*ctx, NULL);
+    g_free(ctx);
+    g_free(hash);
+}
+
+
+static
+int qcrypto_gnutls_hash_update(QCryptoHash *hash,
+                               const struct iovec *iov,
+                               size_t niov,
+                               Error **errp)
+{
+    int ret = 0;
+    gnutls_hash_hd_t *ctx = hash->opaque;
+
+    for (int i = 0; i < niov; i++) {
+        ret = gnutls_hash(*ctx, iov[i].iov_base, iov[i].iov_len);
+        if (ret != 0) {
+            error_setg(errp, "Failed to hash data: %s",
+                       gnutls_strerror(ret));
+            return -1;
+        }
+    }
+
+    return 0;
+}
+
+static
+int qcrypto_gnutls_hash_finalize(QCryptoHash *hash,
+                                 uint8_t **result,
+                                 size_t *result_len,
+                                 Error **errp)
+{
+    gnutls_hash_hd_t *ctx = hash->opaque;
+
+    *result_len = gnutls_hash_get_len(qcrypto_hash_alg_map[hash->alg]);
+    if (*result_len == 0) {
+        error_setg(errp, "Unable to get hash length");
+        return -1;
+    }
+
+    *result = g_new(uint8_t, *result_len);
+    gnutls_hash_output(*ctx, *result);
+    return 0;
+}
 
 QCryptoHashDriver qcrypto_hash_lib_driver = {
     .hash_bytesv = qcrypto_gnutls_hash_bytesv,
+    .hash_new      = qcrypto_gnutls_hash_new,
+    .hash_update   = qcrypto_gnutls_hash_update,
+    .hash_finalize = qcrypto_gnutls_hash_finalize,
+    .hash_free     = qcrypto_gnutls_hash_free,
 };