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Purism-Calls/plugins/sip/calls-sdp-crypto-context.c
Evangelos Ribeiro Tzaras 14350a38ed sip: Add SDP crypto context class
Objects of this type keep track of SDP of the local and remote peers,
allow generating offers and answers and codify default policy used for
cryptographic parameters.
2022-05-24 22:30:03 +02:00

512 lines
14 KiB
C

/*
* Copyright (C) 2022 Purism SPC
*
* This file is part of Calls.
*
* Calls 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 3 of the License, or
* (at your option) any later version.
*
* Calls 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 Calls. If not, see <http://www.gnu.org/licenses/>.
*
* Author: Evangelos Ribeiro Tzaras <evangelos.tzaras@puri.sm>
*
* SPDX-License-Identifier: GPL-3.0-or-later
*
*/
#include "calls-sdp-crypto-context.h"
#include "calls-sip-enums.h"
#include <sofia-sip/sdp.h>
enum {
PROP_0,
PROP_STATE,
PROP_LAST_PROP
};
static GParamSpec *props[PROP_LAST_PROP];
struct _CallsSdpCryptoContext {
GObject parent_instance;
GList *local_crypto_attributes;
GList *remote_crypto_attributes;
CallsCryptoContextState state;
int negotiated_tag;
};
#if GLIB_CHECK_VERSION (2, 70, 0)
G_DEFINE_FINAL_TYPE (CallsSdpCryptoContext, calls_sdp_crypto_context, G_TYPE_OBJECT)
#else
G_DEFINE_TYPE (CallsSdpCryptoContext, calls_sdp_crypto_context, G_TYPE_OBJECT)
#endif
static GStrv
get_all_crypto_attributes_strv (sdp_media_t *media)
{
#if GLIB_CHECK_VERSION (2, 68, 0)
g_autoptr (GStrvBuilder) builder = NULL;
g_assert (media);
builder = g_strv_builder_new ();
for (sdp_attribute_t *attr = media->m_attributes; attr; attr = attr->a_next) {
g_autofree char *crypto_str = NULL;
if (g_strcmp0 (attr->a_name, "crypto") != 0)
continue;
crypto_str = g_strconcat ("a=crypto:", attr->a_value, NULL);
g_strv_builder_add (builder, crypto_str);
}
return g_strv_builder_end (builder);
#else
/* implement a poor mans GStrv */
g_autofree char *attribute_string = NULL;
g_assert (media);
for (sdp_attribute_t *attr = media->m_attributes; attr; attr = attr->a_next) {
g_autofree char *crypto_str = NULL;
if (g_strcmp0 (attr->a_name, "crypto") != 0)
continue;
crypto_str = g_strconcat ("a=crypto:", attr->a_value, NULL);
if (!attribute_string) {
attribute_string = g_strdup (crypto_str);
} else {
g_autofree char *tmp = attribute_string;
attribute_string = g_strconcat (attribute_string, "\n", crypto_str, NULL);
}
}
return g_strsplit (attribute_string, "\n", -1);
#endif
}
static gboolean
crypto_attribute_is_supported (CallsSdpCryptoContext *self,
calls_srtp_crypto_attribute *attr)
{
g_assert (attr);
if (attr->crypto_suite == CALLS_SRTP_SUITE_UNKNOWN)
return FALSE;
/* TODO setup a policy mechanism, for now this is hardcoded */
if (attr->unencrypted_srtp ||
attr->unauthenticated_srtp ||
attr->unencrypted_srtcp)
return FALSE;
return TRUE;
}
static calls_srtp_crypto_attribute *
get_crypto_attribute_by_tag (GList *attributes,
guint tag)
{
g_assert (attributes);
g_assert (tag > 0);
for (GList *node = attributes; node; node = node->next) {
calls_srtp_crypto_attribute *attr = node->data;
if (attr->tag == tag)
return attr;
}
return NULL;
}
static void
set_state (CallsSdpCryptoContext *self,
CallsCryptoContextState state)
{
g_assert (CALLS_IS_SDP_CRYPTO_CONTEXT (self));
if (self->state == state)
return;
self->state = state;
g_object_notify_by_pspec (G_OBJECT (self), props[PROP_STATE]);
}
/* Returns if %TRUE if the state was updated, %FALSE otherwise */
static gboolean
update_state (CallsSdpCryptoContext *self)
{
GList *tags_local = NULL;
GList *tags_remote = NULL;
gint negotiated_tag = -1;
calls_srtp_crypto_attribute *local_crypto;
calls_srtp_crypto_attribute *remote_crypto;
g_assert (CALLS_IS_SDP_CRYPTO_CONTEXT (self));
/* Cannot update final states */
if (self->state == CALLS_CRYPTO_CONTEXT_STATE_NEGOTIATION_FAILED ||
self->state == CALLS_CRYPTO_CONTEXT_STATE_NEGOTIATION_SUCCESS)
return FALSE;
if (self->state == CALLS_CRYPTO_CONTEXT_STATE_INIT) {
if (self->local_crypto_attributes) {
set_state (self, CALLS_CRYPTO_CONTEXT_STATE_OFFER_LOCAL);
return TRUE;
}
if (self->remote_crypto_attributes) {
set_state (self, CALLS_CRYPTO_CONTEXT_STATE_OFFER_REMOTE);
return TRUE;
}
return FALSE;
}
for (GList *node = self->local_crypto_attributes; node; node = node->next) {
calls_srtp_crypto_attribute *attr = node->data;
tags_local = g_list_append (tags_local, GUINT_TO_POINTER (attr->tag));
}
for (GList *node = self->remote_crypto_attributes; node; node = node->next) {
calls_srtp_crypto_attribute *attr = node->data;
tags_remote = g_list_append (tags_remote, GUINT_TO_POINTER (attr->tag));
}
if (self->state == CALLS_CRYPTO_CONTEXT_STATE_OFFER_LOCAL) {
for (GList *node = tags_local; node; node = node->next) {
if (g_list_find (tags_remote, node->data)) {
negotiated_tag = GPOINTER_TO_UINT (node->data);
break;
}
}
} else if (self->state == CALLS_CRYPTO_CONTEXT_STATE_OFFER_REMOTE) {
for (GList *node = tags_remote; node; node = node->next) {
if (g_list_find (tags_local, node->data)) {
negotiated_tag = GPOINTER_TO_UINT (node->data);
break;
}
}
} else {
g_assert_not_reached ();
}
g_list_free (tags_local);
g_list_free (tags_remote);
if (negotiated_tag == -1) {
self->state = CALLS_CRYPTO_CONTEXT_STATE_NEGOTIATION_FAILED;
return TRUE;
}
local_crypto = get_crypto_attribute_by_tag (self->local_crypto_attributes,
negotiated_tag);
remote_crypto = get_crypto_attribute_by_tag (self->remote_crypto_attributes,
negotiated_tag);
if (local_crypto->crypto_suite != remote_crypto->crypto_suite) {
set_state (self, CALLS_CRYPTO_CONTEXT_STATE_NEGOTIATION_FAILED);
return TRUE;
}
/* TODO check mandatory parameters and policy constrains */
self->negotiated_tag = negotiated_tag;
set_state (self, CALLS_CRYPTO_CONTEXT_STATE_NEGOTIATION_SUCCESS);
return TRUE;
}
static void
calls_sdp_crypto_context_get_property (GObject *object,
guint property_id,
GValue *value,
GParamSpec *pspec)
{
CallsSdpCryptoContext *self = CALLS_SDP_CRYPTO_CONTEXT (object);
switch (property_id) {
case PROP_STATE:
g_value_set_enum (value, self->state);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
break;
}
}
static void
calls_sdp_crypto_context_dispose (GObject *object)
{
CallsSdpCryptoContext *self = CALLS_SDP_CRYPTO_CONTEXT (object);
g_clear_list (&self->local_crypto_attributes, (GDestroyNotify) calls_srtp_crypto_attribute_free);
g_clear_list (&self->remote_crypto_attributes, (GDestroyNotify) calls_srtp_crypto_attribute_free);
G_OBJECT_CLASS (calls_sdp_crypto_context_parent_class)->dispose (object);
}
static void
calls_sdp_crypto_context_class_init (CallsSdpCryptoContextClass *klass)
{
GObjectClass *object_class = G_OBJECT_CLASS (klass);
object_class->dispose = calls_sdp_crypto_context_dispose;
object_class->get_property = calls_sdp_crypto_context_get_property;
props[PROP_STATE] =
g_param_spec_enum ("state",
"State",
"State of the crypto context",
CALLS_TYPE_CRYPTO_CONTEXT_STATE,
CALLS_CRYPTO_CONTEXT_STATE_INIT,
G_PARAM_READABLE | G_PARAM_STATIC_STRINGS);
g_object_class_install_properties (object_class, PROP_LAST_PROP, props);
}
static void
calls_sdp_crypto_context_init (CallsSdpCryptoContext *self)
{
}
CallsSdpCryptoContext *
calls_sdp_crypto_context_new (void)
{
return g_object_new (CALLS_TYPE_SDP_CRYPTO_CONTEXT, NULL);
}
gboolean
calls_sdp_crypto_context_set_local_media (CallsSdpCryptoContext *self,
sdp_media_t *media)
{
g_auto (GStrv) crypto_strv = NULL;
guint n_crypto_attr;
g_return_val_if_fail (CALLS_IS_SDP_CRYPTO_CONTEXT (self), FALSE);
g_return_val_if_fail (media, FALSE);
if (self->local_crypto_attributes) {
g_warning ("Local crypto attributes already set");
return FALSE;
}
crypto_strv = get_all_crypto_attributes_strv (media);
n_crypto_attr = g_strv_length (crypto_strv);
if (n_crypto_attr == 0) {
g_warning ("No crypto attributes found in given SDP media");
return FALSE;
}
for (guint i = 0; i < n_crypto_attr; i++) {
g_autoptr (GError) error = NULL;
calls_srtp_crypto_attribute *attr;
attr = calls_srtp_parse_sdp_crypto_attribute (crypto_strv[i], &error);
if (!attr) {
g_warning ("Failed parsing crypto attribute '%s': %s",
crypto_strv[i], error->message);
continue;
}
self->local_crypto_attributes =
g_list_append (self->local_crypto_attributes, attr);
}
if (!self->local_crypto_attributes) {
g_warning ("Could not parse a single crypto attribute, aborting");
return FALSE;
}
return update_state (self);
}
gboolean
calls_sdp_crypto_context_set_remote_media (CallsSdpCryptoContext *self,
sdp_media_t *media)
{
g_auto (GStrv) crypto_strv = NULL;
guint n_crypto_attr;
g_return_val_if_fail (CALLS_IS_SDP_CRYPTO_CONTEXT (self), FALSE);
g_return_val_if_fail (media, FALSE);
if (self->remote_crypto_attributes) {
g_warning ("Remote crypto attributes already set");
return FALSE;
}
crypto_strv = get_all_crypto_attributes_strv (media);
n_crypto_attr = g_strv_length (crypto_strv);
if (n_crypto_attr == 0) {
g_warning ("No crypto attributes found in given SDP media");
return FALSE;
}
for (guint i = 0; i < n_crypto_attr; i++) {
g_autoptr (GError) error = NULL;
calls_srtp_crypto_attribute *attr;
attr = calls_srtp_parse_sdp_crypto_attribute (crypto_strv[i], &error);
if (!attr) {
g_warning ("Failed parsing crypto attribute '%s': %s",
crypto_strv[i], error->message);
continue;
}
self->remote_crypto_attributes =
g_list_append (self->remote_crypto_attributes, attr);
}
if (!self->remote_crypto_attributes) {
g_warning ("Could not parse a single crypto attribute, aborting");
return FALSE;
}
return update_state (self);
}
calls_srtp_crypto_attribute *
calls_sdp_crypto_context_get_local_crypto (CallsSdpCryptoContext *self)
{
g_return_val_if_fail (CALLS_IS_SDP_CRYPTO_CONTEXT (self), NULL);
if (self->state != CALLS_CRYPTO_CONTEXT_STATE_NEGOTIATION_SUCCESS)
return NULL;
return get_crypto_attribute_by_tag (self->local_crypto_attributes,
self->negotiated_tag);
}
calls_srtp_crypto_attribute *
calls_sdp_crypto_context_get_remote_crypto (CallsSdpCryptoContext *self)
{
g_return_val_if_fail (CALLS_IS_SDP_CRYPTO_CONTEXT (self), NULL);
if (self->state != CALLS_CRYPTO_CONTEXT_STATE_NEGOTIATION_SUCCESS)
return NULL;
return get_crypto_attribute_by_tag (self->remote_crypto_attributes,
self->negotiated_tag);
}
gboolean
calls_sdp_crypto_context_generate_offer (CallsSdpCryptoContext *self)
{
calls_srtp_crypto_attribute *attr;
g_return_val_if_fail (CALLS_IS_SDP_CRYPTO_CONTEXT (self), FALSE);
if (self->state != CALLS_CRYPTO_CONTEXT_STATE_INIT) {
g_warning ("Cannot generate offer. Need INIT state, but found %d",
self->state);
return FALSE;
}
g_assert (!self->local_crypto_attributes);
attr = calls_srtp_crypto_attribute_new (1);
attr->tag = 1;
attr->crypto_suite = CALLS_SRTP_SUITE_AES_128_SHA1_80;
calls_srtp_crypto_attribute_init_keys (attr);
self->local_crypto_attributes = g_list_append (NULL, attr);
attr = calls_srtp_crypto_attribute_new (1);
attr->tag = 2;
attr->crypto_suite = CALLS_SRTP_SUITE_AES_128_SHA1_32;
calls_srtp_crypto_attribute_init_keys (attr);
self->local_crypto_attributes = g_list_append (self->local_crypto_attributes, attr);
return update_state (self);
}
gboolean
calls_sdp_crypto_context_generate_answer (CallsSdpCryptoContext *self)
{
calls_srtp_crypto_attribute *attr = NULL;
g_return_val_if_fail (CALLS_IS_SDP_CRYPTO_CONTEXT (self), FALSE);
if (self->state != CALLS_CRYPTO_CONTEXT_STATE_OFFER_REMOTE) {
g_warning ("Cannot generate answer. Need OFFER_REMOTE state, but found %d",
self->state);
return FALSE;
}
for (GList *node = self->remote_crypto_attributes; node; node = node->next) {
calls_srtp_crypto_attribute *attr_offer = node->data;
if (crypto_attribute_is_supported (self, attr_offer)) {
attr = calls_srtp_crypto_attribute_new (1);
attr->crypto_suite = attr_offer->crypto_suite;
attr->tag = attr_offer->tag;
calls_srtp_crypto_attribute_init_keys (attr);
}
}
if (!attr)
return FALSE;
self->local_crypto_attributes = g_list_append (NULL, attr);
return update_state (self);
}
gboolean
calls_sdp_crypto_context_get_is_negotiated (CallsSdpCryptoContext *self)
{
g_return_val_if_fail (CALLS_IS_SDP_CRYPTO_CONTEXT (self), FALSE);
return self->state == CALLS_CRYPTO_CONTEXT_STATE_NEGOTIATION_SUCCESS;
}
CallsCryptoContextState
calls_sdp_crypto_context_get_state (CallsSdpCryptoContext *self)
{
g_return_val_if_fail (CALLS_IS_SDP_CRYPTO_CONTEXT (self), CALLS_CRYPTO_CONTEXT_STATE_INIT);
return self->state;
}
GList *
calls_sdp_crypto_context_get_crypto_candidates (CallsSdpCryptoContext *self,
gboolean remote)
{
g_return_val_if_fail (CALLS_IS_SDP_CRYPTO_CONTEXT (self), NULL);
return g_list_copy (remote ? self->remote_crypto_attributes : self->local_crypto_attributes);
}