pidgin/pidgin

certificate: Use public key fingerprint to compare certificates
release-2.x.y
2017-03-07, dx
887efbd652d8
certificate: Use public key fingerprint to compare certificates

This fixes an issue with google talk's certificates and gnutls, where the root
certificate in the provided chain is a slightly different version of the one
that is usually present in the certificate stores, but the SubjectPublicKeyInfo
section is the same.

This adds a PurpleCertificateScheme function, compare_pubkeys, and its wrapper
purple_certificate_compare_pubkeys().

This is only implemented for gnutls, since the NSS plugin only uses the NSS
certificate validation code. Even if that path was reachable from a plugin that
doesn't implement this method, it would return FALSE and behave as if this bug
was never fixed.

The gnutls implementation uses the gnutls_x509_crt_get_key_id() function,
which returns a hash of the SubjectPublicKeyInfo section of the certificate.

In gnutls versions older than 3.4.1, this may be a SHA1 hash, but after that
version SHA256 support was added (without much fanfare - the documentation
barely mentions this at all), and we just use the constant for the best known
algo, which for current versions is just SHA256. Older versions ignore that
flag parameter.

The whole comparison is modeled after the private _gnutls_check_if_same_key(),
which checks if both certificates have the same DN ("unique id") and does a
memcmp() of the raw SPKI section. We don't have direct access to the raw SPKI
section but comparing their fingerprints is good enough.
/**
* @file dbus-bindings.h Purple DBUS Bindings
* @ingroup core
*/
/* purple
*
* Purple is the legal property of its developers, whose names are too numerous
* to list here. Please refer to the COPYRIGHT file distributed with this
* source distribution.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02111-1301 USA
*
*/
#ifndef _PURPLE_DBUS_BINDINGS_H_
#define _PURPLE_DBUS_BINDINGS_H_
#include <dbus/dbus.h>
#include <dbus/dbus-glib-lowlevel.h>
#include <glib.h>
#ifdef __cplusplus
extern "C" {
#endif
gint purple_dbus_pointer_to_id(gconstpointer node);
gpointer purple_dbus_id_to_pointer(gint id, PurpleDBusType *type);
gint purple_dbus_pointer_to_id_error(gconstpointer ptr, DBusError *error);
gpointer purple_dbus_id_to_pointer_error(gint id, PurpleDBusType *type,
const char *typename, DBusError *error);
#define NULLIFY(id) id = empty_to_null(id)
#define CHECK_ERROR(error) if (dbus_error_is_set(error)) return NULL;
#define PURPLE_DBUS_ID_TO_POINTER(ptr, id, type, error) \
G_STMT_START { \
ptr = (type*) purple_dbus_id_to_pointer_error \
(id, PURPLE_DBUS_TYPE(type), #type, error); \
CHECK_ERROR(error); \
} G_STMT_END
#define PURPLE_DBUS_POINTER_TO_ID(id, ptr, error) \
G_STMT_START { \
id = purple_dbus_pointer_to_id_error(ptr,error); \
CHECK_ERROR(error); \
} G_STMT_END
dbus_bool_t
purple_dbus_message_get_args (DBusMessage *message,
DBusError *error,
int first_arg_type,
...);
dbus_bool_t
purple_dbus_message_get_args_valist (DBusMessage *message,
DBusError *error,
int first_arg_type,
va_list var_args);
dbus_bool_t
purple_dbus_message_iter_get_args (DBusMessageIter *iter,
DBusError *error,
int first_arg_type,
...);
dbus_bool_t
purple_dbus_message_iter_get_args_valist (DBusMessageIter *iter,
DBusError *error,
int first_arg_type,
va_list var_args);
dbus_int32_t* purple_dbusify_GList(GList *list, gboolean free_memory,
dbus_int32_t *len);
dbus_int32_t* purple_dbusify_GSList(GSList *list, gboolean free_memory,
dbus_int32_t *len);
gpointer* purple_GList_to_array(GList *list, gboolean free_memory,
dbus_int32_t *len);
gpointer* purple_GSList_to_array(GSList *list, gboolean free_memory,
dbus_int32_t *len);
GHashTable *purple_dbus_iter_hash_table(DBusMessageIter *iter, DBusError *error);
const char* empty_to_null(const char *str);
const char* null_to_empty(const char *s);
typedef struct {
const char *name;
const char *parameters;
DBusMessage* (*handler)(DBusMessage *request, DBusError *error);
} PurpleDBusBinding;
void purple_dbus_register_bindings(void *handle, PurpleDBusBinding *bindings);
DBusConnection *purple_dbus_get_connection(void);
#ifdef __cplusplus
}
#endif
#endif