sip: Add srtp-utilities

These utilities aid in generating and parsing SDP crypto attributes to be used during the offer/answer negotiation.
2022-04-14 17:09:57 +02:00
parent 5cd03a8a13
commit 4937723541
5 changed files with 1051 additions and 0 deletions
--- a/plugins/sip/calls-srtp-utils.h
+++ b/plugins/sip/calls-srtp-utils.h
@@ -0,0 +1,106 @@
+/*
+ * 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
+ *
+ */
+
+#pragma once
+
+#include <glib.h>
+
+G_BEGIN_DECLS
+
+typedef enum {
+  CALLS_SRTP_SUITE_UNKNOWN = 0,
+  CALLS_SRTP_SUITE_AES_128_SHA1_32,
+  CALLS_SRTP_SUITE_AES_128_SHA1_80,
+} calls_srtp_crypto_suite;
+
+
+typedef enum {
+  CALLS_SRTP_FEC_ORDER_UNSET = 0,
+  CALLS_SRTP_FEC_ORDER_FEC_SRTP,
+  CALLS_SRTP_FEC_ORDER_SRTP_FEC
+} calls_srtp_fec_order;
+
+
+typedef enum {
+  CALLS_SRTP_LIFETIME_UNSET = 0,
+  CALLS_SRTP_LIFETIME_AS_DECIMAL_NUMBER,
+  CALLS_SRTP_LIFETIME_AS_POWER_OF_TWO
+} calls_srtp_lifetime_type;
+
+
+typedef struct {
+  char                    *b64_keysalt;
+  calls_srtp_lifetime_type lifetime_type;
+  /* maximum lifetime: SRTP 2^48 packets; SRTCP 2^31 packets; libsrtp uses a hardcoded limit of 2^48 */
+  guint64                  lifetime;
+
+  guint64                  mki;
+  guint                    mki_length;
+} calls_srtp_crypto_key_param;
+
+
+typedef struct {
+  gint                         tag;
+  calls_srtp_crypto_suite      crypto_suite;
+
+  calls_srtp_crypto_key_param *key_params;
+  guint                        n_key_params;
+
+  /** session parameters
+   * For more information see https://datatracker.ietf.org/doc/html/rfc4568#section-6.3
+   * KDR (key derivation rate) defaults to 0; declarative parameter
+   *  decimal integer in {1,2,...,24}, denotes a power of two. 0 means unspecified
+   *  defaulting to a single initial key derivation
+   * UNENCRYPTED_SRTCP, UNENCRYPTED_SRTP; negotiated parameter
+   * UNAUTHENTICATED_SRTP; negotiated parameter
+   * FEC_ORDER; declarative parameter
+   * FEC_KEY separate key-params for forward error correction; declarative parameter
+   * WSH (Window Size Hint); declarative parameter; MAY be ignored
+   */
+  gint                 kdr;
+  gboolean             unencrypted_srtp;
+  gboolean             unencrypted_srtcp;
+  gboolean             unauthenticated_srtp;
+  calls_srtp_fec_order fec_order; /* FEC in RTP: RFC2733 */
+  char                *b64_fec_key; /* TODO this should also be an array of calls_srtp_crypto_key_param */
+  guint                window_size_hint;
+} calls_srtp_crypto_attribute;
+
+
+guchar                      *calls_srtp_generate_key_salt              (gsize length);
+guchar                      *calls_srtp_generate_key_salt_for_suite    (calls_srtp_crypto_suite suite);
+calls_srtp_crypto_attribute *calls_srtp_parse_sdp_crypto_attribute     (const char *attr,
+                                                                        GError    **error);
+char                        *calls_srtp_print_sdp_crypto_attribute     (calls_srtp_crypto_attribute *attr,
+                                                                        GError                     **error);
+calls_srtp_crypto_attribute *calls_srtp_crypto_attribute_new           (guint n_key_params);
+gboolean                     calls_srtp_crypto_attribute_init_keys     (calls_srtp_crypto_attribute *attr);
+void                         calls_srtp_crypto_attribute_free          (calls_srtp_crypto_attribute *attr);
+char                        *calls_srtp_generate_crypto_for_offer      (void);
+
+
+G_DEFINE_AUTOPTR_CLEANUP_FUNC (calls_srtp_crypto_attribute, calls_srtp_crypto_attribute_free)
+
+
+G_END_DECLS