1 files changed, 119 insertions, 0 deletions
diff --git a/shared/nm-utils/nm-hash-utils.c b/shared/nm-utils/nm-hash-utils.c
new file mode 100644
index 00000000..c563140e
--- /dev/null
+++ b/shared/nm-utils/nm-hash-utils.c
@@ -0,0 +1,119 @@
+/* -*- Mode: C; tab-width: 4; indent-tabs-mode: t; c-basic-offset: 4 -*- */
+/* NetworkManager -- Network link manager
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301 USA.
+ *
+ * (C) Copyright 2017 Red Hat, Inc.
+ */
+
+#include "nm-default.h"
+
+#include "nm-hash-utils.h"
+
+#include <stdint.h>
+
+#include "nm-shared-utils.h"
+#include "nm-random-utils.h"
+
+/*****************************************************************************/
+
+#define HASH_KEY_SIZE 16u
+#define HASH_KEY_SIZE_GUINT ((HASH_KEY_SIZE + sizeof (guint) - 1) / sizeof (guint))
+
+G_STATIC_ASSERT (sizeof (guint) * HASH_KEY_SIZE_GUINT >= HASH_KEY_SIZE);
+
+static const guint8 *
+_get_hash_key (void)
+{
+	static const guint8 *volatile global_seed = NULL;
+	const guint8 *g;
+
+	g = global_seed;
+	if (G_UNLIKELY (g == NULL)) {
+		/* the returned hash is aligned to guin64, hence, it is save
+		 * to use it as guint* or guint64* pointer. */
+		static union {
+			guint8 v8[HASH_KEY_SIZE];
+		} g_arr _nm_alignas (guint64);
+		static gsize g_lock;
+
+		if (g_once_init_enter (&g_lock)) {
+			nm_utils_random_bytes (g_arr.v8, sizeof (g_arr.v8));
+			g_atomic_pointer_compare_and_exchange (&global_seed, NULL, g_arr.v8);
+			g = g_arr.v8;
+			g_once_init_leave (&g_lock, 1);
+		} else {
+			g = global_seed;
+			nm_assert (g);
+		}
+	}
+
+	return g;
+}
+
+void
+nm_hash_init (NMHashState *state, guint static_seed)
+{
+	const guint8 *g;
+	guint seed[HASH_KEY_SIZE_GUINT];
+
+	nm_assert (state);
+
+	g = _get_hash_key ();
+	memcpy (seed, g, HASH_KEY_SIZE);
+	seed[0] ^= static_seed;
+	siphash24_init (&state->_state, (const guint8 *) seed);
+}
+
+guint
+nm_hash_str (const char *str)
+{
+	NMHashState h;
+
+	if (str) {
+		nm_hash_init (&h, 1867854211u);
+		nm_hash_update_str (&h, str);
+	} else
+		nm_hash_init (&h, 842995561u);
+	return nm_hash_complete (&h);
+}
+
+guint
+nm_str_hash (gconstpointer str)
+{
+	return nm_hash_str (str);
+}
+
+guint
+nm_hash_ptr (gconstpointer ptr)
+{
+	guint h;
+
+	h = ((const guint *) _get_hash_key ())[0];
+
+	if (sizeof (ptr) <= sizeof (guint))
+		h = h ^ ((guint) ((uintptr_t) ptr));
+	else
+		h = h ^ ((guint) (((guint64) (uintptr_t) ptr) >> 32)) ^ ((guint) ((uintptr_t) ptr));
+
+	return h ?: 2907677551u;
+}
+
+guint
+nm_direct_hash (gconstpointer ptr)
+{
+	return nm_hash_ptr (ptr);
+}