TLS: really delay key lookup until it is necessary

Even if the certificate has a RSA public key, be sure to lookup the key
only if it is an actual RSA key exchange. Move the hashtable to the
secrets module to enable reuse.

Change-Id: I39010831079d3b65d5d4368ec97d02491c1615a5
Reviewed-on: https://code.wireshark.org/review/30854
Petri-Dish: Peter Wu <peter@lekensteyn.nl>
Tested-by: Petri Dish Buildbot
Reviewed-by: Anders Broman <a.broman58@gmail.com>

1 files changed, 36 insertions, 0 deletions

diff --git a/epan/secrets.c b/epan/secrets.c
index 08ed299a3e..c539a95e06 100644
--- a/epan/secrets.c
+++ b/epan/secrets.c
@@ -9,9 +9,17 @@
  * SPDX-License-Identifier: GPL-2.0-or-later
  */
 
+#include "config.h"
+
 #include "secrets.h"
 #include <wiretap/wtap.h>
 
+#include <string.h>
+#ifdef HAVE_LIBGNUTLS
+#include <gnutls/gnutls.h>
+#include <gnutls/abstract.h>
+#endif  /* HAVE_LIBGNUTLS */
+
 /** Maps guint32 secrets_type -> secrets_block_callback_t. */
 static GHashTable *secrets_callbacks;
 
@@ -44,6 +52,34 @@ secrets_wtap_callback(guint32 secrets_type, const void *secrets, guint size)
     }
 }
 
+#ifdef HAVE_LIBGNUTLS
+static guint
+key_id_hash(gconstpointer key)
+{
+    const cert_key_id_t *key_id = (const cert_key_id_t *)key;
+    const guint32 *dw = (const guint32 *)key_id->key_id;
+
+    /* The public key' SHA-1 hash (which maps to a private key) has a uniform
+     * distribution, hence simply xor'ing them should be sufficient. */
+    return dw[0] ^ dw[1] ^ dw[2] ^ dw[3] ^ dw[4];
+}
+
+static gboolean
+key_id_equal(gconstpointer a, gconstpointer b)
+{
+    const cert_key_id_t *key_id_a = (const cert_key_id_t *)a;
+    const cert_key_id_t *key_id_b = (const cert_key_id_t *)b;
+
+    return !memcmp(key_id_a, key_id_b, sizeof(*key_id_a));
+}
+
+GHashTable *
+privkey_hash_table_new(void)
+{
+    return g_hash_table_new_full(key_id_hash, key_id_equal, g_free, (GDestroyNotify)gnutls_privkey_deinit);
+}
+#endif  /* HAVE_LIBGNUTLS */
+
 /*
  * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
  *