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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-19 00:47:55 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-19 00:47:55 +0000
commit26a029d407be480d791972afb5975cf62c9360a6 (patch)
treef435a8308119effd964b339f76abb83a57c29483 /third_party/libsrtp/src/include
parentInitial commit. (diff)
downloadfirefox-26a029d407be480d791972afb5975cf62c9360a6.tar.xz
firefox-26a029d407be480d791972afb5975cf62c9360a6.zip
Adding upstream version 124.0.1.upstream/124.0.1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'third_party/libsrtp/src/include')
-rw-r--r--third_party/libsrtp/src/include/config.h6
-rw-r--r--third_party/libsrtp/src/include/srtp.h1747
-rw-r--r--third_party/libsrtp/src/include/srtp2/meson.build8
-rw-r--r--third_party/libsrtp/src/include/srtp_priv.h278
4 files changed, 2039 insertions, 0 deletions
diff --git a/third_party/libsrtp/src/include/config.h b/third_party/libsrtp/src/include/config.h
new file mode 100644
index 0000000000..75e05e897f
--- /dev/null
+++ b/third_party/libsrtp/src/include/config.h
@@ -0,0 +1,6 @@
+/*
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+/* empty file; config done via Makefile.in & configure.in */
diff --git a/third_party/libsrtp/src/include/srtp.h b/third_party/libsrtp/src/include/srtp.h
new file mode 100644
index 0000000000..fa34daf641
--- /dev/null
+++ b/third_party/libsrtp/src/include/srtp.h
@@ -0,0 +1,1747 @@
+/*
+ * srtp.h
+ *
+ * interface to libsrtp
+ *
+ * David A. McGrew
+ * Cisco Systems, Inc.
+ */
+/*
+ *
+ * Copyright (c) 2001-2017, Cisco Systems, Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following
+ * disclaimer in the documentation and/or other materials provided
+ * with the distribution.
+ *
+ * Neither the name of the Cisco Systems, Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived
+ * from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
+ * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#ifndef SRTP_SRTP_H
+#define SRTP_SRTP_H
+
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @defgroup SRTP Secure RTP
+ *
+ * @brief libSRTP provides functions for protecting RTP and RTCP. See
+ * Section @ref Overview for an introduction to the use of the library.
+ *
+ * @{
+ */
+
+/*
+ * SRTP_MASTER_KEY_LEN is the nominal master key length supported by libSRTP
+ */
+
+#define SRTP_MASTER_KEY_LEN 30
+
+/*
+ * SRTP_MAX_KEY_LEN is the maximum key length supported by libSRTP
+ */
+#define SRTP_MAX_KEY_LEN 64
+
+/*
+ * SRTP_MAX_TAG_LEN is the maximum tag length supported by libSRTP
+ */
+
+#define SRTP_MAX_TAG_LEN 16
+
+/**
+ * SRTP_MAX_MKI_LEN is the maximum size the MKI could be which is
+ * 128 bytes
+ */
+#define SRTP_MAX_MKI_LEN 128
+
+/**
+ * SRTP_MAX_TRAILER_LEN is the maximum length of the SRTP trailer
+ * (authentication tag and MKI) supported by libSRTP. This value is
+ * the maximum number of octets that will be added to an RTP packet by
+ * srtp_protect().
+ *
+ * @brief the maximum number of octets added by srtp_protect().
+ */
+#define SRTP_MAX_TRAILER_LEN (SRTP_MAX_TAG_LEN + SRTP_MAX_MKI_LEN)
+
+/**
+ * SRTP_MAX_NUM_MASTER_KEYS is the maximum number of Master keys for
+ * MKI supported by libSRTP.
+ *
+ */
+#define SRTP_MAX_NUM_MASTER_KEYS 16
+
+#define SRTP_SALT_LEN 14
+
+/*
+ * SRTP_AEAD_SALT_LEN is the length of the SALT values used with
+ * GCM mode. GCM mode requires an IV. The SALT value is used
+ * as part of the IV formation logic applied to each RTP packet.
+ */
+#define SRTP_AEAD_SALT_LEN 12
+
+#define SRTP_AES_128_KEY_LEN 16
+#define SRTP_AES_192_KEY_LEN 24
+#define SRTP_AES_256_KEY_LEN 32
+
+#define SRTP_AES_ICM_128_KEY_LEN_WSALT (SRTP_SALT_LEN + SRTP_AES_128_KEY_LEN)
+#define SRTP_AES_ICM_192_KEY_LEN_WSALT (SRTP_SALT_LEN + SRTP_AES_192_KEY_LEN)
+#define SRTP_AES_ICM_256_KEY_LEN_WSALT (SRTP_SALT_LEN + SRTP_AES_256_KEY_LEN)
+
+#define SRTP_AES_GCM_128_KEY_LEN_WSALT \
+ (SRTP_AEAD_SALT_LEN + SRTP_AES_128_KEY_LEN)
+#define SRTP_AES_GCM_192_KEY_LEN_WSALT \
+ (SRTP_AEAD_SALT_LEN + SRTP_AES_192_KEY_LEN)
+#define SRTP_AES_GCM_256_KEY_LEN_WSALT \
+ (SRTP_AEAD_SALT_LEN + SRTP_AES_256_KEY_LEN)
+
+/**
+ * @brief A srtp_cipher_type_id_t is an identifier for a particular cipher
+ * type.
+ *
+ * A srtp_cipher_type_id_t is an integer that represents a particular
+ * cipher type, e.g. the Advanced Encryption Standard (AES). A
+ * SRTP_NULL_CIPHER is available; this cipher leaves the data unchanged,
+ * and can be selected to indicate that no encryption is to take
+ * place.
+ *
+ * @ingroup Ciphers
+ */
+typedef uint32_t srtp_cipher_type_id_t;
+
+/**
+ * @brief An srtp_auth_type_id_t is an identifier for a particular
+ * authentication
+ * function.
+ *
+ * An srtp_auth_type_id_t is an integer that represents a particular
+ * authentication function type, e.g. HMAC-SHA1. A SRTP_NULL_AUTH is
+ * available; this authentication function performs no computation,
+ * and can be selected to indicate that no authentication is to take
+ * place.
+ *
+ * @ingroup Authentication
+ */
+typedef uint32_t srtp_auth_type_id_t;
+
+/**
+ * @brief srtp_err_status_t defines error codes.
+ *
+ * The enumeration srtp_err_status_t defines error codes. Note that the
+ * value of srtp_err_status_ok is equal to zero, which can simplify error
+ * checking somewhat.
+ *
+ */
+typedef enum {
+ srtp_err_status_ok = 0, /**< nothing to report */
+ srtp_err_status_fail = 1, /**< unspecified failure */
+ srtp_err_status_bad_param = 2, /**< unsupported parameter */
+ srtp_err_status_alloc_fail = 3, /**< couldn't allocate memory */
+ srtp_err_status_dealloc_fail = 4, /**< couldn't deallocate properly */
+ srtp_err_status_init_fail = 5, /**< couldn't initialize */
+ srtp_err_status_terminus = 6, /**< can't process as much data as */
+ /**< requested */
+ srtp_err_status_auth_fail = 7, /**< authentication failure */
+ srtp_err_status_cipher_fail = 8, /**< cipher failure */
+ srtp_err_status_replay_fail = 9, /**< replay check failed (bad index) */
+ srtp_err_status_replay_old = 10, /**< replay check failed (index too */
+ /**< old) */
+ srtp_err_status_algo_fail = 11, /**< algorithm failed test routine */
+ srtp_err_status_no_such_op = 12, /**< unsupported operation */
+ srtp_err_status_no_ctx = 13, /**< no appropriate context found */
+ srtp_err_status_cant_check = 14, /**< unable to perform desired */
+ /**< validation */
+ srtp_err_status_key_expired = 15, /**< can't use key any more */
+ srtp_err_status_socket_err = 16, /**< error in use of socket */
+ srtp_err_status_signal_err = 17, /**< error in use POSIX signals */
+ srtp_err_status_nonce_bad = 18, /**< nonce check failed */
+ srtp_err_status_read_fail = 19, /**< couldn't read data */
+ srtp_err_status_write_fail = 20, /**< couldn't write data */
+ srtp_err_status_parse_err = 21, /**< error parsing data */
+ srtp_err_status_encode_err = 22, /**< error encoding data */
+ srtp_err_status_semaphore_err = 23, /**< error while using semaphores */
+ srtp_err_status_pfkey_err = 24, /**< error while using pfkey */
+ srtp_err_status_bad_mki = 25, /**< error MKI present in packet is */
+ /**< invalid */
+ srtp_err_status_pkt_idx_old = 26, /**< packet index is too old to */
+ /**< consider */
+ srtp_err_status_pkt_idx_adv = 27 /**< packet index advanced, reset */
+ /**< needed */
+} srtp_err_status_t;
+
+typedef struct srtp_ctx_t_ srtp_ctx_t;
+
+/**
+ * @brief srtp_sec_serv_t describes a set of security services.
+ *
+ * A srtp_sec_serv_t enumeration is used to describe the particular
+ * security services that will be applied by a particular crypto
+ * policy (or other mechanism).
+ */
+typedef enum {
+ sec_serv_none = 0, /**< no services */
+ sec_serv_conf = 1, /**< confidentiality */
+ sec_serv_auth = 2, /**< authentication */
+ sec_serv_conf_and_auth = 3 /**< confidentiality and authentication */
+} srtp_sec_serv_t;
+
+/**
+ * @brief srtp_crypto_policy_t describes a particular crypto policy that
+ * can be applied to an SRTP stream.
+ *
+ * A srtp_crypto_policy_t describes a particular cryptographic policy that
+ * can be applied to an SRTP or SRTCP stream. An SRTP session policy
+ * consists of a list of these policies, one for each SRTP stream
+ * in the session.
+ */
+typedef struct srtp_crypto_policy_t {
+ srtp_cipher_type_id_t cipher_type; /**< An integer representing */
+ /**< the type of cipher. */
+ int cipher_key_len; /**< The length of the cipher key */
+ /**< in octets. */
+ srtp_auth_type_id_t auth_type; /**< An integer representing the */
+ /**< authentication function. */
+ int auth_key_len; /**< The length of the authentication */
+ /**< function key in octets. */
+ int auth_tag_len; /**< The length of the authentication */
+ /**< tag in octets. */
+ srtp_sec_serv_t sec_serv; /**< The flag indicating the security */
+ /**< services to be applied. */
+} srtp_crypto_policy_t;
+
+/**
+ * @brief srtp_ssrc_type_t describes the type of an SSRC.
+ *
+ * An srtp_ssrc_type_t enumeration is used to indicate a type of SSRC. See
+ * @ref srtp_policy_t for more information.
+ */
+typedef enum {
+ ssrc_undefined = 0, /**< Indicates an undefined SSRC type. */
+ ssrc_specific = 1, /**< Indicates a specific SSRC value */
+ ssrc_any_inbound = 2, /**< Indicates any inbound SSRC value */
+ /**< (i.e. a value that is used in the */
+ /**< function srtp_unprotect()) */
+ ssrc_any_outbound = 3 /**< Indicates any outbound SSRC value */
+ /**< (i.e. a value that is used in the */
+ /**< function srtp_protect()) */
+} srtp_ssrc_type_t;
+
+/**
+ * @brief An srtp_ssrc_t represents a particular SSRC value, or a `wildcard'
+ * SSRC.
+ *
+ * An srtp_ssrc_t represents a particular SSRC value (if its type is
+ * ssrc_specific), or a wildcard SSRC value that will match all
+ * outbound SSRCs (if its type is ssrc_any_outbound) or all inbound
+ * SSRCs (if its type is ssrc_any_inbound).
+ */
+typedef struct {
+ srtp_ssrc_type_t type; /**< The type of this particular SSRC */
+ unsigned int value; /**< The value of this SSRC, if it is not a */
+ /**< wildcard */
+} srtp_ssrc_t;
+
+/**
+ * @brief srtp_master_key_t represents a master key. There will
+ * be a Master Key Index and the Master Key associated with the
+ * Master Key Index. Need to also keep track of the Master Key
+ * Index Size to correctly read it from a packet.
+ */
+typedef struct srtp_master_key_t {
+ unsigned char *key;
+ unsigned char *mki_id;
+ unsigned int mki_size;
+} srtp_master_key_t;
+
+/**
+ * @brief represents the policy for an SRTP session.
+ *
+ * A single srtp_policy_t struct represents the policy for a single
+ * SRTP stream, and a linked list of these elements represents the
+ * policy for an entire SRTP session. Each element contains the SRTP
+ * and SRTCP crypto policies for that stream, a pointer to the SRTP
+ * master key for that stream, the SSRC describing that stream, or a
+ * flag indicating a `wildcard' SSRC value, and a `next' field that
+ * holds a pointer to the next element in the list of policy elements,
+ * or NULL if it is the last element.
+ *
+ * The wildcard value SSRC_ANY_INBOUND matches any SSRC from an
+ * inbound stream that for which there is no explicit SSRC entry in
+ * another policy element. Similarly, the value SSRC_ANY_OUTBOUND
+ * will matches any SSRC from an outbound stream that does not appear
+ * in another policy element. Note that wildcard SSRCs &b cannot be
+ * used to match both inbound and outbound traffic. This restriction
+ * is intentional, and it allows libSRTP to ensure that no security
+ * lapses result from accidental re-use of SSRC values during key
+ * sharing.
+ *
+ * @warning The final element of the list @b must have its `next' pointer
+ * set to NULL.
+ */
+
+typedef struct srtp_policy_t {
+ srtp_ssrc_t ssrc; /**< The SSRC value of stream, or the */
+ /**< flags SSRC_ANY_INBOUND or */
+ /**< SSRC_ANY_OUTBOUND if key sharing */
+ /**< is used for this policy element. */
+ srtp_crypto_policy_t rtp; /**< SRTP crypto policy. */
+ srtp_crypto_policy_t rtcp; /**< SRTCP crypto policy. */
+ unsigned char *key; /**< Pointer to the SRTP master key for */
+ /**< this stream. */
+ srtp_master_key_t **keys; /** Array of Master Key structures */
+ unsigned long num_master_keys; /** Number of master keys */
+ void *deprecated_ekt; /**< DEPRECATED: pointer to the EKT */
+ /**< policy structure for this stream */
+ unsigned long window_size; /**< The window size to use for replay */
+ /**< protection. */
+ int allow_repeat_tx; /**< Whether retransmissions of */
+ /**< packets with the same sequence */
+ /**< number are allowed. */
+ /**< (Note that such repeated */
+ /**< transmissions must have the same */
+ /**< RTP payload, or a severe security */
+ /**< weakness is introduced!) */
+ int *enc_xtn_hdr; /**< List of header ids to encrypt. */
+ int enc_xtn_hdr_count; /**< Number of entries in list of header */
+ /**< ids. */
+ struct srtp_policy_t *next; /**< Pointer to next stream policy. */
+} srtp_policy_t;
+
+/**
+ * @brief An srtp_t points to an SRTP session structure.
+ *
+ * The typedef srtp_t is a pointer to a structure that represents
+ * an SRTP session. This datatype is intentionally opaque in
+ * order to separate the interface from the implementation.
+ *
+ * An SRTP session consists of all of the traffic sent to the RTP and
+ * RTCP destination transport addresses, using the RTP/SAVP (Secure
+ * Audio/Video Profile). A session can be viewed as a set of SRTP
+ * streams, each of which originates with a different participant.
+ */
+typedef srtp_ctx_t *srtp_t;
+
+/**
+ * @brief srtp_init() initializes the srtp library.
+ *
+ * @warning This function @b must be called before any other srtp
+ * functions.
+ */
+srtp_err_status_t srtp_init(void);
+
+/**
+ * @brief srtp_shutdown() de-initializes the srtp library.
+ *
+ * @warning No srtp functions may be called after calling this function.
+ */
+srtp_err_status_t srtp_shutdown(void);
+
+/**
+ * @brief srtp_protect() is the Secure RTP sender-side packet processing
+ * function.
+ *
+ * The function call srtp_protect(ctx, rtp_hdr, len_ptr) applies SRTP
+ * protection to the RTP packet rtp_hdr (which has length *len_ptr) using
+ * the SRTP context ctx. If srtp_err_status_ok is returned, then rtp_hdr
+ * points to the resulting SRTP packet and *len_ptr is the number of
+ * octets in that packet; otherwise, no assumptions should be made
+ * about the value of either data elements.
+ *
+ * The sequence numbers of the RTP packets presented to this function
+ * need not be consecutive, but they @b must be out of order by less
+ * than 2^15 = 32,768 packets.
+ *
+ * @warning This function assumes that it can write the authentication
+ * tag into the location in memory immediately following the RTP
+ * packet, and assumes that the RTP packet is aligned on a 32-bit
+ * boundary.
+ *
+ * @warning This function assumes that it can write SRTP_MAX_TRAILER_LEN
+ * into the location in memory immediately following the RTP packet.
+ * Callers MUST ensure that this much writable memory is available in
+ * the buffer that holds the RTP packet.
+ *
+ * @param ctx is the SRTP context to use in processing the packet.
+ *
+ * @param rtp_hdr is a pointer to the RTP packet (before the call); after
+ * the function returns, it points to the srtp packet.
+ *
+ * @param len_ptr is a pointer to the length in octets of the complete
+ * RTP packet (header and body) before the function call, and of the
+ * complete SRTP packet after the call, if srtp_err_status_ok was returned.
+ * Otherwise, the value of the data to which it points is undefined.
+ *
+ * @return
+ * - srtp_err_status_ok no problems
+ * - srtp_err_status_replay_fail rtp sequence number was non-increasing
+ * - @e other failure in cryptographic mechanisms
+ */
+srtp_err_status_t srtp_protect(srtp_t ctx, void *rtp_hdr, int *len_ptr);
+
+/**
+ * @brief srtp_protect_mki() is the Secure RTP sender-side packet processing
+ * function that can utilize MKI.
+ *
+ * The function call srtp_protect(ctx, rtp_hdr, len_ptr) applies SRTP
+ * protection to the RTP packet rtp_hdr (which has length *len_ptr) using
+ * the SRTP context ctx. If srtp_err_status_ok is returned, then rtp_hdr
+ * points to the resulting SRTP packet and *len_ptr is the number of
+ * octets in that packet; otherwise, no assumptions should be made
+ * about the value of either data elements.
+ *
+ * The sequence numbers of the RTP packets presented to this function
+ * need not be consecutive, but they @b must be out of order by less
+ * than 2^15 = 32,768 packets.
+ *
+ * @warning This function assumes that it can write the authentication
+ * tag into the location in memory immediately following the RTP
+ * packet, and assumes that the RTP packet is aligned on a 32-bit
+ * boundary.
+ *
+ * @warning This function assumes that it can write SRTP_MAX_TRAILER_LEN
+ * into the location in memory immediately following the RTP packet.
+ * Callers MUST ensure that this much writable memory is available in
+ * the buffer that holds the RTP packet.
+ *
+ * @param ctx is the SRTP context to use in processing the packet.
+ *
+ * @param rtp_hdr is a pointer to the RTP packet (before the call); after
+ * the function returns, it points to the srtp packet.
+ *
+ * @param pkt_octet_len is a pointer to the length in octets of the complete
+ * RTP packet (header and body) before the function call, and of the
+ * complete SRTP packet after the call, if srtp_err_status_ok was returned.
+ * Otherwise, the value of the data to which it points is undefined.
+ *
+ * @param use_mki is a boolean to tell the system if mki is being used. If
+ * set to false then will use the first set of session keys. If set to true
+ * will
+ * use the session keys identified by the mki_index
+ *
+ * @param mki_index integer value specifying which set of session keys should be
+ * used if use_mki is set to true.
+ *
+ * @return
+ * - srtp_err_status_ok no problems
+ * - srtp_err_status_replay_fail rtp sequence number was non-increasing
+ * - @e other failure in cryptographic mechanisms
+ */
+srtp_err_status_t srtp_protect_mki(srtp_ctx_t *ctx,
+ void *rtp_hdr,
+ int *pkt_octet_len,
+ unsigned int use_mki,
+ unsigned int mki_index);
+
+/**
+ * @brief srtp_unprotect() is the Secure RTP receiver-side packet
+ * processing function.
+ *
+ * The function call srtp_unprotect(ctx, srtp_hdr, len_ptr) verifies
+ * the Secure RTP protection of the SRTP packet pointed to by srtp_hdr
+ * (which has length *len_ptr), using the SRTP context ctx. If
+ * srtp_err_status_ok is returned, then srtp_hdr points to the resulting
+ * RTP packet and *len_ptr is the number of octets in that packet;
+ * otherwise, no assumptions should be made about the value of either
+ * data elements.
+ *
+ * The sequence numbers of the RTP packets presented to this function
+ * need not be consecutive, but they @b must be out of order by less
+ * than 2^15 = 32,768 packets.
+ *
+ * @warning This function assumes that the SRTP packet is aligned on a
+ * 32-bit boundary.
+ *
+ * @param ctx is the SRTP session which applies to the particular packet.
+ *
+ * @param srtp_hdr is a pointer to the header of the SRTP packet
+ * (before the call). after the function returns, it points to the
+ * rtp packet if srtp_err_status_ok was returned; otherwise, the value of
+ * the data to which it points is undefined.
+ *
+ * @param len_ptr is a pointer to the length in octets of the complete
+ * srtp packet (header and body) before the function call, and of the
+ * complete rtp packet after the call, if srtp_err_status_ok was returned.
+ * Otherwise, the value of the data to which it points is undefined.
+ *
+ * @return
+ * - srtp_err_status_ok if the RTP packet is valid.
+ * - srtp_err_status_auth_fail if the SRTP packet failed the message
+ * authentication check.
+ * - srtp_err_status_replay_fail if the SRTP packet is a replay (e.g. packet
+ * has already been processed and accepted).
+ * - [other] if there has been an error in the cryptographic mechanisms.
+ *
+ */
+srtp_err_status_t srtp_unprotect(srtp_t ctx, void *srtp_hdr, int *len_ptr);
+
+/**
+ * @brief srtp_unprotect_mki() is the Secure RTP receiver-side packet
+ * processing function that checks for MKI.
+ *
+ * The function call srtp_unprotect(ctx, srtp_hdr, len_ptr) verifies
+ * the Secure RTP protection of the SRTP packet pointed to by srtp_hdr
+ * (which has length *len_ptr), using the SRTP context ctx. If
+ * srtp_err_status_ok is returned, then srtp_hdr points to the resulting
+ * RTP packet and *len_ptr is the number of octets in that packet;
+ * otherwise, no assumptions should be made about the value of either
+ * data elements.
+ *
+ * The sequence numbers of the RTP packets presented to this function
+ * need not be consecutive, but they @b must be out of order by less
+ * than 2^15 = 32,768 packets.
+ *
+ * @warning This function assumes that the SRTP packet is aligned on a
+ * 32-bit boundary.
+ *
+ * @param ctx is the SRTP session which applies to the particular packet.
+ *
+ * @param srtp_hdr is a pointer to the header of the SRTP packet
+ * (before the call). after the function returns, it points to the
+ * rtp packet if srtp_err_status_ok was returned; otherwise, the value of
+ * the data to which it points is undefined.
+ *
+ * @param len_ptr is a pointer to the length in octets of the complete
+ * srtp packet (header and body) before the function call, and of the
+ * complete rtp packet after the call, if srtp_err_status_ok was returned.
+ * Otherwise, the value of the data to which it points is undefined.
+ *
+ * @param use_mki is a boolean to tell the system if mki is being used. If
+ * set to false then will use the first set of session keys. If set to true
+ * will
+ * use the session keys identified by the mki_index
+ *
+ * @return
+ * - srtp_err_status_ok if the RTP packet is valid.
+ * - srtp_err_status_auth_fail if the SRTP packet failed the message
+ * authentication check.
+ * - srtp_err_status_replay_fail if the SRTP packet is a replay (e.g. packet
+ * has already been processed and accepted).
+ * - srtp_err_status_bad_mki if the MKI in the packet is not a known MKI id
+ * - [other] if there has been an error in the cryptographic mechanisms.
+ *
+ */
+srtp_err_status_t srtp_unprotect_mki(srtp_t ctx,
+ void *srtp_hdr,
+ int *len_ptr,
+ unsigned int use_mki);
+
+/**
+ * @brief srtp_create() allocates and initializes an SRTP session.
+
+ * The function call srtp_create(session, policy) allocates and
+ * initializes an SRTP session context, applying the given policy.
+ *
+ * @param session is a pointer to the SRTP session to which the policy is
+ * to be added.
+ *
+ * @param policy is the srtp_policy_t struct that describes the policy
+ * for the session. The struct may be a single element, or it may be
+ * the head of a list, in which case each element of the list is
+ * processed. It may also be NULL, in which case streams should be added
+ * later using srtp_add_stream(). The final element of the list @b must
+ * have its `next' field set to NULL.
+ *
+ * @return
+ * - srtp_err_status_ok if creation succeeded.
+ * - srtp_err_status_alloc_fail if allocation failed.
+ * - srtp_err_status_init_fail if initialization failed.
+ */
+srtp_err_status_t srtp_create(srtp_t *session, const srtp_policy_t *policy);
+
+/**
+ * @brief srtp_add_stream() allocates and initializes an SRTP stream
+ * within a given SRTP session.
+ *
+ * The function call srtp_add_stream(session, policy) allocates and
+ * initializes a new SRTP stream within a given, previously created
+ * session, applying the policy given as the other argument to that
+ * stream.
+ *
+ * @return values:
+ * - srtp_err_status_ok if stream creation succeeded.
+ * - srtp_err_status_alloc_fail if stream allocation failed
+ * - srtp_err_status_init_fail if stream initialization failed.
+ */
+srtp_err_status_t srtp_add_stream(srtp_t session, const srtp_policy_t *policy);
+
+/**
+ * @brief srtp_remove_stream() deallocates an SRTP stream.
+ *
+ * The function call srtp_remove_stream(session, ssrc) removes
+ * the SRTP stream with the SSRC value ssrc from the SRTP session
+ * context given by the argument session.
+ *
+ * @param session is the SRTP session from which the stream
+ * will be removed.
+ *
+ * @param ssrc is the SSRC value of the stream to be removed
+ * in network byte order.
+ *
+ * @warning Wildcard SSRC values cannot be removed from a
+ * session.
+ *
+ * @return
+ * - srtp_err_status_ok if the stream deallocation succeeded.
+ * - [other] otherwise.
+ *
+ */
+srtp_err_status_t srtp_remove_stream(srtp_t session, unsigned int ssrc);
+
+/**
+ * @brief srtp_update() updates all streams in the session.
+ *
+ * The function call srtp_update(session, policy) updates
+ * all the streams in the session applying the given policy
+ * and key. The existing ROC value of all streams will be
+ * preserved.
+ *
+ * @param session is the SRTP session that contains the streams
+ * to be updated.
+ *
+ * @param policy is the srtp_policy_t struct that describes the policy
+ * for the session. The struct may be a single element, or it may be
+ * the head of a list, in which case each element of the list is
+ * processed. The final element of the list @b must
+ * have its `next' field set to NULL.
+ *
+ * @return
+ * - srtp_err_status_ok if stream creation succeed.
+ * - srtp_err_status_alloc_fail if stream allocation failed
+ * - srtp_err_status_init_fail if stream initialization failed.
+ * - [other] otherwise.
+ *
+ */
+srtp_err_status_t srtp_update(srtp_t session, const srtp_policy_t *policy);
+
+/**
+ * @brief srtp_update_stream() updates a SRTP stream.
+ *
+ * The function call srtp_update_stream(session, policy) updates
+ * the stream(s) in the session that match applying the given
+ * policy and key. The existing ROC value of all stream(s) will
+ * be preserved.
+ *
+ * @param session is the SRTP session that contains the streams
+ * to be updated.
+ *
+ * @param policy is the srtp_policy_t struct that describes the policy
+ * for the session.
+ *
+ * @return
+ * - srtp_err_status_ok if stream creation succeeded.
+ * - srtp_err_status_alloc_fail if stream allocation failed
+ * - srtp_err_status_init_fail if stream initialization failed.
+ * - [other] otherwise.
+ *
+ */
+srtp_err_status_t srtp_update_stream(srtp_t session,
+ const srtp_policy_t *policy);
+
+/**
+ * @brief srtp_crypto_policy_set_rtp_default() sets a crypto policy
+ * structure to the SRTP default policy for RTP protection.
+ *
+ * @param p is a pointer to the policy structure to be set
+ *
+ * The function call srtp_crypto_policy_set_rtp_default(&p) sets the
+ * srtp_crypto_policy_t at location p to the SRTP default policy for RTP
+ * protection, as defined in the specification. This function is a
+ * convenience that helps to avoid dealing directly with the policy
+ * data structure. You are encouraged to initialize policy elements
+ * with this function call. Doing so may allow your code to be
+ * forward compatible with later versions of libSRTP that include more
+ * elements in the srtp_crypto_policy_t datatype.
+ *
+ * @return void.
+ *
+ */
+void srtp_crypto_policy_set_rtp_default(srtp_crypto_policy_t *p);
+
+/**
+ * @brief srtp_crypto_policy_set_rtcp_default() sets a crypto policy
+ * structure to the SRTP default policy for RTCP protection.
+ *
+ * @param p is a pointer to the policy structure to be set
+ *
+ * The function call srtp_crypto_policy_set_rtcp_default(&p) sets the
+ * srtp_crypto_policy_t at location p to the SRTP default policy for RTCP
+ * protection, as defined in the specification. This function is a
+ * convenience that helps to avoid dealing directly with the policy
+ * data structure. You are encouraged to initialize policy elements
+ * with this function call. Doing so may allow your code to be
+ * forward compatible with later versions of libSRTP that include more
+ * elements in the srtp_crypto_policy_t datatype.
+ *
+ * @return void.
+ *
+ */
+void srtp_crypto_policy_set_rtcp_default(srtp_crypto_policy_t *p);
+
+/**
+ * @brief srtp_crypto_policy_set_aes_cm_128_hmac_sha1_80() sets a crypto
+ * policy structure to the SRTP default policy for RTP protection.
+ *
+ * @param p is a pointer to the policy structure to be set
+ *
+ * The function srtp_crypto_policy_set_aes_cm_128_hmac_sha1_80() is a
+ * synonym for srtp_crypto_policy_set_rtp_default(). It conforms to the
+ * naming convention used in RFC 4568 (SDP Security Descriptions for
+ * Media Streams).
+ *
+ * @return void.
+ *
+ */
+#define srtp_crypto_policy_set_aes_cm_128_hmac_sha1_80(p) \
+ srtp_crypto_policy_set_rtp_default(p)
+
+/**
+ * @brief srtp_crypto_policy_set_aes_cm_128_hmac_sha1_32() sets a crypto
+ * policy structure to a short-authentication tag policy
+ *
+ * @param p is a pointer to the policy structure to be set
+ *
+ * The function call srtp_crypto_policy_set_aes_cm_128_hmac_sha1_32(&p)
+ * sets the srtp_crypto_policy_t at location p to use policy
+ * AES_CM_128_HMAC_SHA1_32 as defined in RFC 4568.
+ * This policy uses AES-128
+ * Counter Mode encryption and HMAC-SHA1 authentication, with an
+ * authentication tag that is only 32 bits long. This length is
+ * considered adequate only for protecting audio and video media that
+ * use a stateless playback function. See Section 7.5 of RFC 3711
+ * (http://www.ietf.org/rfc/rfc3711.txt).
+ *
+ * This function is a convenience that helps to avoid dealing directly
+ * with the policy data structure. You are encouraged to initialize
+ * policy elements with this function call. Doing so may allow your
+ * code to be forward compatible with later versions of libSRTP that
+ * include more elements in the srtp_crypto_policy_t datatype.
+ *
+ * @warning This crypto policy is intended for use in SRTP, but not in
+ * SRTCP. It is recommended that a policy that uses longer
+ * authentication tags be used for SRTCP. See Section 7.5 of RFC 3711
+ * (http://www.ietf.org/rfc/rfc3711.txt).
+ *
+ * @return void.
+ *
+ */
+void srtp_crypto_policy_set_aes_cm_128_hmac_sha1_32(srtp_crypto_policy_t *p);
+
+/**
+ * @brief srtp_crypto_policy_set_aes_cm_128_null_auth() sets a crypto
+ * policy structure to an encryption-only policy
+ *
+ * @param p is a pointer to the policy structure to be set
+ *
+ * The function call srtp_crypto_policy_set_aes_cm_128_null_auth(&p) sets
+ * the srtp_crypto_policy_t at location p to use the SRTP default cipher
+ * (AES-128 Counter Mode), but to use no authentication method. This
+ * policy is NOT RECOMMENDED unless it is unavoidable; see Section 7.5
+ * of RFC 3711 (http://www.ietf.org/rfc/rfc3711.txt).
+ *
+ * This function is a convenience that helps to avoid dealing directly
+ * with the policy data structure. You are encouraged to initialize
+ * policy elements with this function call. Doing so may allow your
+ * code to be forward compatible with later versions of libSRTP that
+ * include more elements in the srtp_crypto_policy_t datatype.
+ *
+ * @warning This policy is NOT RECOMMENDED for SRTP unless it is
+ * unavoidable, and it is NOT RECOMMENDED at all for SRTCP; see
+ * Section 7.5 of RFC 3711 (http://www.ietf.org/rfc/rfc3711.txt).
+ *
+ * @return void.
+ *
+ */
+void srtp_crypto_policy_set_aes_cm_128_null_auth(srtp_crypto_policy_t *p);
+
+/**
+ * @brief srtp_crypto_policy_set_null_cipher_hmac_sha1_80() sets a crypto
+ * policy structure to an authentication-only policy
+ *
+ * @param p is a pointer to the policy structure to be set
+ *
+ * The function call srtp_crypto_policy_set_null_cipher_hmac_sha1_80(&p)
+ * sets the srtp_crypto_policy_t at location p to use HMAC-SHA1 with an 80
+ * bit authentication tag to provide message authentication, but to
+ * use no encryption. This policy is NOT RECOMMENDED for SRTP unless
+ * there is a requirement to forgo encryption.
+ *
+ * This function is a convenience that helps to avoid dealing directly
+ * with the policy data structure. You are encouraged to initialize
+ * policy elements with this function call. Doing so may allow your
+ * code to be forward compatible with later versions of libSRTP that
+ * include more elements in the srtp_crypto_policy_t datatype.
+ *
+ * @warning This policy is NOT RECOMMENDED for SRTP unless there is a
+ * requirement to forgo encryption.
+ *
+ * @return void.
+ *
+ */
+void srtp_crypto_policy_set_null_cipher_hmac_sha1_80(srtp_crypto_policy_t *p);
+
+/**
+ * @brief srtp_crypto_policy_set_null_cipher_hmac_null() sets a crypto
+ * policy structure to use no encryption or authentication.
+ *
+ * @param p is a pointer to the policy structure to be set
+ *
+ * The function call srtp_crypto_policy_set_null_cipher_hmac_null(&p)
+ * sets the srtp_crypto_policy_t at location p to use no encryption and
+ * no authentication. This policy should only be used for testing and
+ * troubleshooting.
+ *
+ * This function is a convenience that helps to avoid dealing directly
+ * with the policy data structure. You are encouraged to initialize
+ * policy elements with this function call. Doing so may allow your
+ * code to be forward compatible with later versions of libSRTP that
+ * include more elements in the srtp_crypto_policy_t datatype.
+ *
+ * @warning This policy is NOT RECOMMENDED for SRTP unless there is a
+ * requirement to forgo encryption and authentication.
+ *
+ * @return void.
+ *
+ */
+void srtp_crypto_policy_set_null_cipher_hmac_null(srtp_crypto_policy_t *p);
+
+/**
+ * @brief srtp_crypto_policy_set_aes_cm_256_hmac_sha1_80() sets a crypto
+ * policy structure to a encryption and authentication policy using AES-256
+ * for RTP protection.
+ *
+ * @param p is a pointer to the policy structure to be set
+ *
+ * The function call srtp_crypto_policy_set_aes_cm_256_hmac_sha1_80(&p)
+ * sets the srtp_crypto_policy_t at location p to use policy
+ * AES_CM_256_HMAC_SHA1_80 as defined in RFC 6188. This policy uses AES-256
+ * Counter Mode encryption and HMAC-SHA1 authentication, with an 80 bit
+ * authentication tag.
+ *
+ * This function is a convenience that helps to avoid dealing directly
+ * with the policy data structure. You are encouraged to initialize
+ * policy elements with this function call. Doing so may allow your
+ * code to be forward compatible with later versions of libSRTP that
+ * include more elements in the srtp_crypto_policy_t datatype.
+ *
+ * @return void.
+ *
+ */
+void srtp_crypto_policy_set_aes_cm_256_hmac_sha1_80(srtp_crypto_policy_t *p);
+
+/**
+ * @brief srtp_crypto_policy_set_aes_cm_256_hmac_sha1_32() sets a crypto
+ * policy structure to a short-authentication tag policy using AES-256
+ * encryption.
+ *
+ * @param p is a pointer to the policy structure to be set
+ *
+ * The function call srtp_crypto_policy_set_aes_cm_256_hmac_sha1_32(&p)
+ * sets the srtp_crypto_policy_t at location p to use policy
+ * AES_CM_256_HMAC_SHA1_32 as defined in RFC 6188. This policy uses AES-256
+ * Counter Mode encryption and HMAC-SHA1 authentication, with an
+ * authentication tag that is only 32 bits long. This length is
+ * considered adequate only for protecting audio and video media that
+ * use a stateless playback function. See Section 7.5 of RFC 3711
+ * (http://www.ietf.org/rfc/rfc3711.txt).
+ *
+ * This function is a convenience that helps to avoid dealing directly
+ * with the policy data structure. You are encouraged to initialize
+ * policy elements with this function call. Doing so may allow your
+ * code to be forward compatible with later versions of libSRTP that
+ * include more elements in the srtp_crypto_policy_t datatype.
+ *
+ * @warning This crypto policy is intended for use in SRTP, but not in
+ * SRTCP. It is recommended that a policy that uses longer
+ * authentication tags be used for SRTCP. See Section 7.5 of RFC 3711
+ * (http://www.ietf.org/rfc/rfc3711.txt).
+ *
+ * @return void.
+ *
+ */
+void srtp_crypto_policy_set_aes_cm_256_hmac_sha1_32(srtp_crypto_policy_t *p);
+
+/**
+ * @brief srtp_crypto_policy_set_aes_cm_256_null_auth() sets a crypto
+ * policy structure to an encryption-only policy
+ *
+ * @param p is a pointer to the policy structure to be set
+ *
+ * The function call srtp_crypto_policy_set_aes_cm_256_null_auth(&p) sets
+ * the srtp_crypto_policy_t at location p to use the SRTP default cipher
+ * (AES-256 Counter Mode), but to use no authentication method. This
+ * policy is NOT RECOMMENDED unless it is unavoidable; see Section 7.5
+ * of RFC 3711 (http://www.ietf.org/rfc/rfc3711.txt).
+ *
+ * This function is a convenience that helps to avoid dealing directly
+ * with the policy data structure. You are encouraged to initialize
+ * policy elements with this function call. Doing so may allow your
+ * code to be forward compatible with later versions of libSRTP that
+ * include more elements in the srtp_crypto_policy_t datatype.
+ *
+ * @warning This policy is NOT RECOMMENDED for SRTP unless it is
+ * unavoidable, and it is NOT RECOMMENDED at all for SRTCP; see
+ * Section 7.5 of RFC 3711 (http://www.ietf.org/rfc/rfc3711.txt).
+ *
+ * @return void.
+ *
+ */
+void srtp_crypto_policy_set_aes_cm_256_null_auth(srtp_crypto_policy_t *p);
+
+/**
+ * @brief srtp_crypto_policy_set_aes_cm_192_hmac_sha1_80() sets a crypto
+ * policy structure to a encryption and authentication policy using AES-192
+ * for RTP protection.
+ *
+ * @param p is a pointer to the policy structure to be set
+ *
+ * The function call srtp_crypto_policy_set_aes_cm_192_hmac_sha1_80(&p)
+ * sets the srtp_crypto_policy_t at location p to use policy
+ * AES_CM_192_HMAC_SHA1_80 as defined in RFC 6188. This policy uses AES-192
+ * Counter Mode encryption and HMAC-SHA1 authentication, with an 80 bit
+ * authentication tag.
+ *
+ * This function is a convenience that helps to avoid dealing directly
+ * with the policy data structure. You are encouraged to initialize
+ * policy elements with this function call. Doing so may allow your
+ * code to be forward compatible with later versions of libSRTP that
+ * include more elements in the srtp_crypto_policy_t datatype.
+ *
+ * @return void.
+ *
+ */
+void srtp_crypto_policy_set_aes_cm_192_hmac_sha1_80(srtp_crypto_policy_t *p);
+
+/**
+ * @brief srtp_crypto_policy_set_aes_cm_192_hmac_sha1_32() sets a crypto
+ * policy structure to a short-authentication tag policy using AES-192
+ * encryption.
+ *
+ * @param p is a pointer to the policy structure to be set
+ *
+ * The function call srtp_crypto_policy_set_aes_cm_192_hmac_sha1_32(&p)
+ * sets the srtp_crypto_policy_t at location p to use policy
+ * AES_CM_192_HMAC_SHA1_32 as defined in RFC 6188. This policy uses AES-192
+ * Counter Mode encryption and HMAC-SHA1 authentication, with an
+ * authentication tag that is only 32 bits long. This length is
+ * considered adequate only for protecting audio and video media that
+ * use a stateless playback function. See Section 7.5 of RFC 3711
+ * (http://www.ietf.org/rfc/rfc3711.txt).
+ *
+ * This function is a convenience that helps to avoid dealing directly
+ * with the policy data structure. You are encouraged to initialize
+ * policy elements with this function call. Doing so may allow your
+ * code to be forward compatible with later versions of libSRTP that
+ * include more elements in the srtp_crypto_policy_t datatype.
+ *
+ * @warning This crypto policy is intended for use in SRTP, but not in
+ * SRTCP. It is recommended that a policy that uses longer
+ * authentication tags be used for SRTCP. See Section 7.5 of RFC 3711
+ * (http://www.ietf.org/rfc/rfc3711.txt).
+ *
+ * @return void.
+ *
+ */
+void srtp_crypto_policy_set_aes_cm_192_hmac_sha1_32(srtp_crypto_policy_t *p);
+
+/**
+ * @brief srtp_crypto_policy_set_aes_cm_192_null_auth() sets a crypto
+ * policy structure to an encryption-only policy
+ *
+ * @param p is a pointer to the policy structure to be set
+ *
+ * The function call srtp_crypto_policy_set_aes_cm_192_null_auth(&p) sets
+ * the srtp_crypto_policy_t at location p to use the SRTP default cipher
+ * (AES-192 Counter Mode), but to use no authentication method. This
+ * policy is NOT RECOMMENDED unless it is unavoidable; see Section 7.5
+ * of RFC 3711 (http://www.ietf.org/rfc/rfc3711.txt).
+ *
+ * This function is a convenience that helps to avoid dealing directly
+ * with the policy data structure. You are encouraged to initialize
+ * policy elements with this function call. Doing so may allow your
+ * code to be forward compatible with later versions of libSRTP that
+ * include more elements in the srtp_crypto_policy_t datatype.
+ *
+ * @warning This policy is NOT RECOMMENDED for SRTP unless it is
+ * unavoidable, and it is NOT RECOMMENDED at all for SRTCP; see
+ * Section 7.5 of RFC 3711 (http://www.ietf.org/rfc/rfc3711.txt).
+ *
+ * @return void.
+ *
+ */
+void srtp_crypto_policy_set_aes_cm_192_null_auth(srtp_crypto_policy_t *p);
+
+/**
+ * @brief srtp_crypto_policy_set_aes_gcm_128_8_auth() sets a crypto
+ * policy structure to an AEAD encryption policy.
+ *
+ * @param p is a pointer to the policy structure to be set
+ *
+ * The function call srtp_crypto_policy_set_aes_gcm_128_8_auth(&p) sets
+ * the srtp_crypto_policy_t at location p to use the SRTP default cipher
+ * (AES-128 Galois Counter Mode) with 8 octet auth tag. This
+ * policy applies confidentiality and authentication to both the
+ * RTP and RTCP packets.
+ *
+ * This function is a convenience that helps to avoid dealing directly
+ * with the policy data structure. You are encouraged to initialize
+ * policy elements with this function call. Doing so may allow your
+ * code to be forward compatible with later versions of libSRTP that
+ * include more elements in the srtp_crypto_policy_t datatype.
+ *
+ * @return void.
+ *
+ */
+void srtp_crypto_policy_set_aes_gcm_128_8_auth(srtp_crypto_policy_t *p);
+
+/**
+ * @brief srtp_crypto_policy_set_aes_gcm_256_8_auth() sets a crypto
+ * policy structure to an AEAD encryption policy
+ *
+ * @param p is a pointer to the policy structure to be set
+ *
+ * The function call srtp_crypto_policy_set_aes_gcm_256_8_auth(&p) sets
+ * the srtp_crypto_policy_t at location p to use the SRTP default cipher
+ * (AES-256 Galois Counter Mode) with 8 octet auth tag. This
+ * policy applies confidentiality and authentication to both the
+ * RTP and RTCP packets.
+ *
+ * This function is a convenience that helps to avoid dealing directly
+ * with the policy data structure. You are encouraged to initialize
+ * policy elements with this function call. Doing so may allow your
+ * code to be forward compatible with later versions of libSRTP that
+ * include more elements in the srtp_crypto_policy_t datatype.
+ *
+ * @return void.
+ *
+ */
+void srtp_crypto_policy_set_aes_gcm_256_8_auth(srtp_crypto_policy_t *p);
+
+/**
+ * @brief srtp_crypto_policy_set_aes_gcm_128_8_only_auth() sets a crypto
+ * policy structure to an AEAD authentication-only policy
+ *
+ * @param p is a pointer to the policy structure to be set
+ *
+ * The function call srtp_crypto_policy_set_aes_gcm_128_8_only_auth(&p) sets
+ * the srtp_crypto_policy_t at location p to use the SRTP default cipher
+ * (AES-128 Galois Counter Mode) with 8 octet auth tag. This policy
+ * applies confidentiality and authentication to the RTP packets,
+ * but only authentication to the RTCP packets.
+ *
+ * This function is a convenience that helps to avoid dealing directly
+ * with the policy data structure. You are encouraged to initialize
+ * policy elements with this function call. Doing so may allow your
+ * code to be forward compatible with later versions of libSRTP that
+ * include more elements in the srtp_crypto_policy_t datatype.
+ *
+ * @return void.
+ *
+ */
+void srtp_crypto_policy_set_aes_gcm_128_8_only_auth(srtp_crypto_policy_t *p);
+
+/**
+ * @brief srtp_crypto_policy_set_aes_gcm_256_8_only_auth() sets a crypto
+ * policy structure to an AEAD authentication-only policy
+ *
+ * @param p is a pointer to the policy structure to be set
+ *
+ * The function call srtp_crypto_policy_set_aes_gcm_256_8_only_auth(&p) sets
+ * the srtp_crypto_policy_t at location p to use the SRTP default cipher
+ * (AES-256 Galois Counter Mode) with 8 octet auth tag. This policy
+ * applies confidentiality and authentication to the RTP packets,
+ * but only authentication to the RTCP packets.
+ *
+ * This function is a convenience that helps to avoid dealing directly
+ * with the policy data structure. You are encouraged to initialize
+ * policy elements with this function call. Doing so may allow your
+ * code to be forward compatible with later versions of libSRTP that
+ * include more elements in the srtp_crypto_policy_t datatype.
+ *
+ * @return void.
+ *
+ */
+void srtp_crypto_policy_set_aes_gcm_256_8_only_auth(srtp_crypto_policy_t *p);
+
+/**
+ * @brief srtp_crypto_policy_set_aes_gcm_128_16_auth() sets a crypto
+ * policy structure to an AEAD encryption policy.
+ *
+ * @param p is a pointer to the policy structure to be set
+ *
+ * The function call srtp_crypto_policy_set_aes_gcm_128_16_auth(&p) sets
+ * the srtp_crypto_policy_t at location p to use the SRTP default cipher
+ * (AES-128 Galois Counter Mode) with 16 octet auth tag. This
+ * policy applies confidentiality and authentication to both the
+ * RTP and RTCP packets.
+ *
+ * This function is a convenience that helps to avoid dealing directly
+ * with the policy data structure. You are encouraged to initialize
+ * policy elements with this function call. Doing so may allow your
+ * code to be forward compatible with later versions of libSRTP that
+ * include more elements in the srtp_crypto_policy_t datatype.
+ *
+ * @return void.
+ *
+ */
+void srtp_crypto_policy_set_aes_gcm_128_16_auth(srtp_crypto_policy_t *p);
+
+/**
+ * @brief srtp_crypto_policy_set_aes_gcm_256_16_auth() sets a crypto
+ * policy structure to an AEAD encryption policy
+ *
+ * @param p is a pointer to the policy structure to be set
+ *
+ * The function call srtp_crypto_policy_set_aes_gcm_256_16_auth(&p) sets
+ * the srtp_crypto_policy_t at location p to use the SRTP default cipher
+ * (AES-256 Galois Counter Mode) with 16 octet auth tag. This
+ * policy applies confidentiality and authentication to both the
+ * RTP and RTCP packets.
+ *
+ * This function is a convenience that helps to avoid dealing directly
+ * with the policy data structure. You are encouraged to initialize
+ * policy elements with this function call. Doing so may allow your
+ * code to be forward compatible with later versions of libSRTP that
+ * include more elements in the srtp_crypto_policy_t datatype.
+ *
+ * @return void.
+ *
+ */
+void srtp_crypto_policy_set_aes_gcm_256_16_auth(srtp_crypto_policy_t *p);
+
+/**
+ * @brief srtp_dealloc() deallocates storage for an SRTP session
+ * context.
+ *
+ * The function call srtp_dealloc(s) deallocates storage for the
+ * SRTP session context s. This function should be called no more
+ * than one time for each of the contexts allocated by the function
+ * srtp_create().
+ *
+ * @param s is the srtp_t for the session to be deallocated.
+ *
+ * @return
+ * - srtp_err_status_ok if there no problems.
+ * - srtp_err_status_dealloc_fail a memory deallocation failure occurred.
+ */
+srtp_err_status_t srtp_dealloc(srtp_t s);
+
+/*
+ * @brief identifies a particular SRTP profile
+ *
+ * An srtp_profile_t enumeration is used to identify a particular SRTP
+ * profile (that is, a set of algorithms and parameters).
+ */
+typedef enum {
+ srtp_profile_reserved = 0,
+ srtp_profile_aes128_cm_sha1_80 = 1,
+ srtp_profile_aes128_cm_sha1_32 = 2,
+ srtp_profile_null_sha1_80 = 5,
+ srtp_profile_null_sha1_32 = 6,
+ srtp_profile_aead_aes_128_gcm = 7,
+ srtp_profile_aead_aes_256_gcm = 8,
+} srtp_profile_t;
+
+/**
+ * @brief srtp_crypto_policy_set_from_profile_for_rtp() sets a crypto policy
+ * structure to the appropriate value for RTP based on an srtp_profile_t
+ *
+ * @param policy is a pointer to the policy structure to be set
+ *
+ * @param profile is an enumeration for the policy to be set
+ *
+ * The function call srtp_crypto_policy_set_rtp_default(&policy, profile)
+ * sets the srtp_crypto_policy_t at location policy to the policy for RTP
+ * protection, as defined by the srtp_profile_t profile.
+ *
+ * This function is a convenience that helps to avoid dealing directly
+ * with the policy data structure. You are encouraged to initialize
+ * policy elements with this function call. Doing so may allow your
+ * code to be forward compatible with later versions of libSRTP that
+ * include more elements in the srtp_crypto_policy_t datatype.
+ *
+ * @return values
+ * - srtp_err_status_ok no problems were encountered
+ * - srtp_err_status_bad_param the profile is not supported
+ *
+ */
+srtp_err_status_t srtp_crypto_policy_set_from_profile_for_rtp(
+ srtp_crypto_policy_t *policy,
+ srtp_profile_t profile);
+
+/**
+ * @brief srtp_crypto_policy_set_from_profile_for_rtcp() sets a crypto policy
+ * structure to the appropriate value for RTCP based on an srtp_profile_t
+ *
+ * @param policy is a pointer to the policy structure to be set
+ *
+ * @param profile is an enumeration for the policy to be set
+ *
+ * The function call srtp_crypto_policy_set_rtcp_default(&policy, profile)
+ * sets the srtp_crypto_policy_t at location policy to the policy for RTCP
+ * protection, as defined by the srtp_profile_t profile.
+ *
+ * This function is a convenience that helps to avoid dealing directly
+ * with the policy data structure. You are encouraged to initialize
+ * policy elements with this function call. Doing so may allow your
+ * code to be forward compatible with later versions of libSRTP that
+ * include more elements in the srtp_crypto_policy_t datatype.
+ *
+ * @return values
+ * - srtp_err_status_ok no problems were encountered
+ * - srtp_err_status_bad_param the profile is not supported
+ *
+ */
+srtp_err_status_t srtp_crypto_policy_set_from_profile_for_rtcp(
+ srtp_crypto_policy_t *policy,
+ srtp_profile_t profile);
+
+/**
+ * @brief returns the master key length for a given SRTP profile
+ */
+unsigned int srtp_profile_get_master_key_length(srtp_profile_t profile);
+
+/**
+ * @brief returns the master salt length for a given SRTP profile
+ */
+unsigned int srtp_profile_get_master_salt_length(srtp_profile_t profile);
+
+/**
+ * @brief appends the salt to the key
+ *
+ * The function call srtp_append_salt_to_key(k, klen, s, slen)
+ * copies the string s to the location at klen bytes following
+ * the location k.
+ *
+ * @warning There must be at least bytes_in_salt + bytes_in_key bytes
+ * available at the location pointed to by key.
+ *
+ */
+void srtp_append_salt_to_key(unsigned char *key,
+ unsigned int bytes_in_key,
+ unsigned char *salt,
+ unsigned int bytes_in_salt);
+
+/**
+ * @}
+ */
+
+/**
+ * @defgroup SRTCP Secure RTCP
+ * @ingroup SRTP
+ *
+ * @brief Secure RTCP functions are used to protect RTCP traffic.
+ *
+ * RTCP is the control protocol for RTP. libSRTP protects RTCP
+ * traffic in much the same way as it does RTP traffic. The function
+ * srtp_protect_rtcp() applies cryptographic protections to outbound
+ * RTCP packets, and srtp_unprotect_rtcp() verifies the protections on
+ * inbound RTCP packets.
+ *
+ * A note on the naming convention: srtp_protect_rtcp() has an srtp_t
+ * as its first argument, and thus has `srtp_' as its prefix. The
+ * trailing `_rtcp' indicates the protocol on which it acts.
+ *
+ * @{
+ */
+
+/**
+ * @brief srtp_protect_rtcp() is the Secure RTCP sender-side packet
+ * processing function.
+ *
+ * The function call srtp_protect_rtcp(ctx, rtp_hdr, len_ptr) applies
+ * SRTCP protection to the RTCP packet rtcp_hdr (which has length
+ * *len_ptr) using the SRTP session context ctx. If srtp_err_status_ok is
+ * returned, then rtp_hdr points to the resulting SRTCP packet and
+ * *len_ptr is the number of octets in that packet; otherwise, no
+ * assumptions should be made about the value of either data elements.
+ *
+ * @warning This function assumes that it can write the authentication
+ * tag into the location in memory immediately following the RTCP
+ * packet, and assumes that the RTCP packet is aligned on a 32-bit
+ * boundary.
+ *
+ * @warning This function assumes that it can write SRTP_MAX_TRAILER_LEN+4
+ * into the location in memory immediately following the RTCP packet.
+ * Callers MUST ensure that this much writable memory is available in
+ * the buffer that holds the RTCP packet.
+ *
+ * @param ctx is the SRTP context to use in processing the packet.
+ *
+ * @param rtcp_hdr is a pointer to the RTCP packet (before the call); after
+ * the function returns, it points to the srtp packet.
+ *
+ * @param pkt_octet_len is a pointer to the length in octets of the
+ * complete RTCP packet (header and body) before the function call,
+ * and of the complete SRTCP packet after the call, if srtp_err_status_ok
+ * was returned. Otherwise, the value of the data to which it points
+ * is undefined.
+ *
+ * @return
+ * - srtp_err_status_ok if there were no problems.
+ * - [other] if there was a failure in
+ * the cryptographic mechanisms.
+ */
+srtp_err_status_t srtp_protect_rtcp(srtp_t ctx,
+ void *rtcp_hdr,
+ int *pkt_octet_len);
+
+/**
+ * @brief srtp_protect_rtcp_mki() is the Secure RTCP sender-side packet
+ * processing function that can utilize mki.
+ *
+ * The function call srtp_protect_rtcp(ctx, rtp_hdr, len_ptr) applies
+ * SRTCP protection to the RTCP packet rtcp_hdr (which has length
+ * *len_ptr) using the SRTP session context ctx. If srtp_err_status_ok is
+ * returned, then rtp_hdr points to the resulting SRTCP packet and
+ * *len_ptr is the number of octets in that packet; otherwise, no
+ * assumptions should be made about the value of either data elements.
+ *
+ * @warning This function assumes that it can write the authentication
+ * tag into the location in memory immediately following the RTCP
+ * packet, and assumes that the RTCP packet is aligned on a 32-bit
+ * boundary.
+ *
+ * @warning This function assumes that it can write SRTP_MAX_TRAILER_LEN+4
+ * into the location in memory immediately following the RTCP packet.
+ * Callers MUST ensure that this much writable memory is available in
+ * the buffer that holds the RTCP packet.
+ *
+ * @param ctx is the SRTP context to use in processing the packet.
+ *
+ * @param rtcp_hdr is a pointer to the RTCP packet (before the call); after
+ * the function returns, it points to the srtp packet.
+ *
+ * @param pkt_octet_len is a pointer to the length in octets of the
+ * complete RTCP packet (header and body) before the function call,
+ * and of the complete SRTCP packet after the call, if srtp_err_status_ok
+ * was returned. Otherwise, the value of the data to which it points
+ * is undefined.
+ *
+ * @param use_mki is a boolean to tell the system if mki is being used. If
+ * set to false then will use the first set of session keys. If set to true
+ * will
+ * use the session keys identified by the mki_index
+ *
+ * @param mki_index integer value specifying which set of session keys should be
+ * used if use_mki is set to true.
+ *
+ * @return
+ * - srtp_err_status_ok if there were no problems.
+ * - [other] if there was a failure in
+ * the cryptographic mechanisms.
+ */
+srtp_err_status_t srtp_protect_rtcp_mki(srtp_t ctx,
+ void *rtcp_hdr,
+ int *pkt_octet_len,
+ unsigned int use_mki,
+ unsigned int mki_index);
+
+/**
+ * @brief srtp_unprotect_rtcp() is the Secure RTCP receiver-side packet
+ * processing function.
+ *
+ * The function call srtp_unprotect_rtcp(ctx, srtp_hdr, len_ptr)
+ * verifies the Secure RTCP protection of the SRTCP packet pointed to
+ * by srtcp_hdr (which has length *len_ptr), using the SRTP session
+ * context ctx. If srtp_err_status_ok is returned, then srtcp_hdr points
+ * to the resulting RTCP packet and *len_ptr is the number of octets
+ * in that packet; otherwise, no assumptions should be made about the
+ * value of either data elements.
+ *
+ * @warning This function assumes that the SRTCP packet is aligned on a
+ * 32-bit boundary.
+ *
+ * @param ctx is a pointer to the srtp_t which applies to the
+ * particular packet.
+ *
+ * @param srtcp_hdr is a pointer to the header of the SRTCP packet
+ * (before the call). After the function returns, it points to the
+ * rtp packet if srtp_err_status_ok was returned; otherwise, the value of
+ * the data to which it points is undefined.
+ *
+ * @param pkt_octet_len is a pointer to the length in octets of the
+ * complete SRTCP packet (header and body) before the function call,
+ * and of the complete rtp packet after the call, if srtp_err_status_ok was
+ * returned. Otherwise, the value of the data to which it points is
+ * undefined.
+ *
+ * @return
+ * - srtp_err_status_ok if the RTCP packet is valid.
+ * - srtp_err_status_auth_fail if the SRTCP packet failed the message
+ * authentication check.
+ * - srtp_err_status_replay_fail if the SRTCP packet is a replay (e.g. has
+ * already been processed and accepted).
+ * - [other] if there has been an error in the cryptographic mechanisms.
+ *
+ */
+srtp_err_status_t srtp_unprotect_rtcp(srtp_t ctx,
+ void *srtcp_hdr,
+ int *pkt_octet_len);
+
+/**
+ * @brief srtp_unprotect_rtcp() is the Secure RTCP receiver-side packet
+ * processing function.
+ *
+ * The function call srtp_unprotect_rtcp(ctx, srtp_hdr, len_ptr)
+ * verifies the Secure RTCP protection of the SRTCP packet pointed to
+ * by srtcp_hdr (which has length *len_ptr), using the SRTP session
+ * context ctx. If srtp_err_status_ok is returned, then srtcp_hdr points
+ * to the resulting RTCP packet and *len_ptr is the number of octets
+ * in that packet; otherwise, no assumptions should be made about the
+ * value of either data elements.
+ *
+ * @warning This function assumes that the SRTCP packet is aligned on a
+ * 32-bit boundary.
+ *
+ * @param ctx is a pointer to the srtp_t which applies to the
+ * particular packet.
+ *
+ * @param srtcp_hdr is a pointer to the header of the SRTCP packet
+ * (before the call). After the function returns, it points to the
+ * rtp packet if srtp_err_status_ok was returned; otherwise, the value of
+ * the data to which it points is undefined.
+ *
+ * @param pkt_octet_len is a pointer to the length in octets of the
+ * complete SRTCP packet (header and body) before the function call,
+ * and of the complete rtp packet after the call, if srtp_err_status_ok was
+ * returned. Otherwise, the value of the data to which it points is
+ * undefined.
+ *
+ * @param use_mki is a boolean to tell the system if mki is being used. If
+ * set to false then will use the first set of session keys. If set to true
+ * will use the session keys identified by the mki_index
+ *
+ * @return
+ * - srtp_err_status_ok if the RTCP packet is valid.
+ * - srtp_err_status_auth_fail if the SRTCP packet failed the message
+ * authentication check.
+ * - srtp_err_status_replay_fail if the SRTCP packet is a replay (e.g. has
+ * already been processed and accepted).
+ * - srtp_err_status_bad_mki if the MKI in the packet is not a known MKI
+ * id
+ * - [other] if there has been an error in the
+ * cryptographic mechanisms.
+ *
+ */
+srtp_err_status_t srtp_unprotect_rtcp_mki(srtp_t ctx,
+ void *srtcp_hdr,
+ int *pkt_octet_len,
+ unsigned int use_mki);
+
+/**
+ * @}
+ */
+
+/**
+ * @defgroup User data associated to a SRTP session.
+ * @ingroup SRTP
+ *
+ * @brief Store custom user data within a SRTP session.
+ *
+ * @{
+ */
+
+/**
+ * @brief srtp_set_user_data() stores the given pointer into the SRTP
+ * session for later retrieval.
+ *
+ * @param ctx is the srtp_t context in which the given data pointer is
+ * stored.
+ *
+ * @param data is a pointer to the custom information (struct, function,
+ * etc) associated with the SRTP session.
+ *
+ * @return void.
+ *
+ */
+void srtp_set_user_data(srtp_t ctx, void *data);
+
+/**
+ * @brief srtp_get_user_data() retrieves the pointer to the custom data
+ * previously stored with srtp_set_user_data().
+ *
+ * This function is mostly useful for retrieving data associated to a
+ * SRTP session when an event fires. The user can then get such a custom
+ * data by calling this function with the session field of the
+ * srtp_event_data_t struct as argument.
+ *
+ * @param ctx is the srtp_t context in which the given data pointer was
+ * stored.
+ *
+ * @return void* pointer to the user data.
+ *
+ */
+void *srtp_get_user_data(srtp_t ctx);
+
+/**
+ * @}
+ */
+
+/**
+ * @defgroup SRTPevents SRTP events and callbacks
+ * @ingroup SRTP
+ *
+ * @brief libSRTP can use a user-provided callback function to
+ * handle events.
+ *
+ *
+ * libSRTP allows a user to provide a callback function to handle
+ * events that need to be dealt with outside of the data plane (see
+ * the enum srtp_event_t for a description of these events). Dealing
+ * with these events is not a strict necessity; they are not
+ * security-critical, but the application may suffer if they are not
+ * handled. The function srtp_set_event_handler() is used to provide
+ * the callback function.
+ *
+ * A default event handler that merely reports on the events as they
+ * happen is included. It is also possible to set the event handler
+ * function to NULL, in which case all events will just be silently
+ * ignored.
+ *
+ * @{
+ */
+
+/**
+ * @brief srtp_event_t defines events that need to be handled
+ *
+ * The enum srtp_event_t defines events that need to be handled
+ * outside the `data plane', such as SSRC collisions and
+ * key expirations.
+ *
+ * When a key expires or the maximum number of packets has been
+ * reached, an SRTP stream will enter an `expired' state in which no
+ * more packets can be protected or unprotected. When this happens,
+ * it is likely that you will want to either deallocate the stream
+ * (using srtp_remove_stream()), and possibly allocate a new one.
+ *
+ * When an SRTP stream expires, the other streams in the same session
+ * are unaffected, unless key sharing is used by that stream. In the
+ * latter case, all of the streams in the session will expire.
+ */
+typedef enum {
+ event_ssrc_collision, /**< An SSRC collision occurred. */
+ event_key_soft_limit, /**< An SRTP stream reached the soft key */
+ /**< usage limit and will expire soon. */
+ event_key_hard_limit, /**< An SRTP stream reached the hard */
+ /**< key usage limit and has expired. */
+ event_packet_index_limit /**< An SRTP stream reached the hard */
+ /**< packet limit (2^48 packets). */
+} srtp_event_t;
+
+/**
+ * @brief srtp_event_data_t is the structure passed as a callback to
+ * the event handler function
+ *
+ * The struct srtp_event_data_t holds the data passed to the event
+ * handler function.
+ */
+typedef struct srtp_event_data_t {
+ srtp_t session; /**< The session in which the event happened. */
+ uint32_t ssrc; /**< The ssrc in host order of the stream in which */
+ /**< the event happened */
+ srtp_event_t event; /**< An enum indicating the type of event. */
+} srtp_event_data_t;
+
+/**
+ * @brief srtp_event_handler_func_t is the function prototype for
+ * the event handler.
+ *
+ * The typedef srtp_event_handler_func_t is the prototype for the
+ * event handler function. It has as its only argument an
+ * srtp_event_data_t which describes the event that needs to be handled.
+ * There can only be a single, global handler for all events in
+ * libSRTP.
+ */
+typedef void(srtp_event_handler_func_t)(srtp_event_data_t *data);
+
+/**
+ * @brief sets the event handler to the function supplied by the caller.
+ *
+ * The function call srtp_install_event_handler(func) sets the event
+ * handler function to the value func. The value NULL is acceptable
+ * as an argument; in this case, events will be ignored rather than
+ * handled.
+ *
+ * @param func is a pointer to a function that takes an srtp_event_data_t
+ * pointer as an argument and returns void. This function
+ * will be used by libSRTP to handle events.
+ */
+srtp_err_status_t srtp_install_event_handler(srtp_event_handler_func_t func);
+
+/**
+ * @brief Returns the version string of the library.
+ *
+ */
+const char *srtp_get_version_string(void);
+
+/**
+ * @brief Returns the numeric representation of the library version.
+ *
+ */
+unsigned int srtp_get_version(void);
+
+/**
+ * @brief srtp_set_debug_module(mod_name, v)
+ *
+ * sets dynamic debugging to the value v (0 for off, 1 for on) for the
+ * debug module with the name mod_name
+ *
+ * returns err_status_ok on success, err_status_fail otherwise
+ */
+srtp_err_status_t srtp_set_debug_module(const char *mod_name, int v);
+
+/**
+ * @brief srtp_list_debug_modules() outputs a list of debugging modules
+ *
+ */
+srtp_err_status_t srtp_list_debug_modules(void);
+
+/**
+ * @brief srtp_log_level_t defines log levels.
+ *
+ * The enumeration srtp_log_level_t defines log levels reported
+ * in the srtp_log_handler_func_t.
+ *
+ */
+typedef enum {
+ srtp_log_level_error, /**< log level is reporting an error message */
+ srtp_log_level_warning, /**< log level is reporting a warning message */
+ srtp_log_level_info, /**< log level is reporting an info message */
+ srtp_log_level_debug /**< log level is reporting a debug message */
+} srtp_log_level_t;
+
+/**
+ * @brief srtp_log_handler_func_t is the function prototype for
+ * the log handler.
+ *
+ * The typedef srtp_event_handler_func_t is the prototype for the
+ * event handler function. It has as srtp_log_level_t, log
+ * message and data as arguments.
+ * There can only be a single, global handler for all log messages in
+ * libSRTP.
+ */
+typedef void(srtp_log_handler_func_t)(srtp_log_level_t level,
+ const char *msg,
+ void *data);
+
+/**
+ * @brief sets the log handler to the function supplied by the caller.
+ *
+ * The function call srtp_install_log_handler(func) sets the log
+ * handler function to the value func. The value NULL is acceptable
+ * as an argument; in this case, log messages will be ignored.
+ * This function can be called before srtp_init() in order to capture
+ * any logging during start up.
+ *
+ * @param func is a pointer to a function of type srtp_log_handler_func_t.
+ * This function will be used by libSRTP to output log messages.
+ * @param data is a user pointer that will be returned as the data argument in
+ * func.
+ */
+srtp_err_status_t srtp_install_log_handler(srtp_log_handler_func_t func,
+ void *data);
+
+/**
+ * @brief srtp_get_protect_trailer_length(session, use_mki, mki_index, length)
+ *
+ * Determines the length of the amount of data Lib SRTP will add to the
+ * packet during the protect process. The length is returned in the length
+ * parameter
+ *
+ * returns err_status_ok on success, err_status_bad_mki if the MKI index is
+ * invalid
+ *
+ */
+srtp_err_status_t srtp_get_protect_trailer_length(srtp_t session,
+ uint32_t use_mki,
+ uint32_t mki_index,
+ uint32_t *length);
+
+/**
+ * @brief srtp_get_protect_rtcp_trailer_length(session, use_mki, mki_index,
+ * length)
+ *
+ * Determines the length of the amount of data Lib SRTP will add to the
+ * packet during the protect process. The length is returned in the length
+ * parameter
+ *
+ * returns err_status_ok on success, err_status_bad_mki if the MKI index is
+ * invalid
+ *
+ */
+srtp_err_status_t srtp_get_protect_rtcp_trailer_length(srtp_t session,
+ uint32_t use_mki,
+ uint32_t mki_index,
+ uint32_t *length);
+
+/**
+ * @brief srtp_set_stream_roc(session, ssrc, roc)
+ *
+ * Set the roll-over-counter on a session for a given SSRC
+ *
+ * returns err_status_ok on success, srtp_err_status_bad_param if there is no
+ * stream found
+ *
+ */
+srtp_err_status_t srtp_set_stream_roc(srtp_t session,
+ uint32_t ssrc,
+ uint32_t roc);
+
+/**
+ * @brief srtp_get_stream_roc(session, ssrc, roc)
+ *
+ * Get the roll-over-counter on a session for a given SSRC
+ *
+ * returns err_status_ok on success, srtp_err_status_bad_param if there is no
+ * stream found
+ *
+ */
+srtp_err_status_t srtp_get_stream_roc(srtp_t session,
+ uint32_t ssrc,
+ uint32_t *roc);
+
+/**
+ * @}
+ */
+
+/* in host order, so outside the #if */
+#define SRTCP_E_BIT 0x80000000
+
+/* for byte-access */
+#define SRTCP_E_BYTE_BIT 0x80
+#define SRTCP_INDEX_MASK 0x7fffffff
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* SRTP_SRTP_H */
diff --git a/third_party/libsrtp/src/include/srtp2/meson.build b/third_party/libsrtp/src/include/srtp2/meson.build
new file mode 100644
index 0000000000..88d068a338
--- /dev/null
+++ b/third_party/libsrtp/src/include/srtp2/meson.build
@@ -0,0 +1,8 @@
+# Copy public headers scattered across the source tree into a single directory
+# so that we can use it in declare_dependency()
+foreach h : public_headers
+ configure_file(input: h,
+ output: '@BASENAME@.h',
+ copy: true)
+endforeach
+public_incs = include_directories('.')
diff --git a/third_party/libsrtp/src/include/srtp_priv.h b/third_party/libsrtp/src/include/srtp_priv.h
new file mode 100644
index 0000000000..48dc65c7d8
--- /dev/null
+++ b/third_party/libsrtp/src/include/srtp_priv.h
@@ -0,0 +1,278 @@
+/*
+ * srtp_priv.h
+ *
+ * private internal data structures and functions for libSRTP
+ *
+ * David A. McGrew
+ * Cisco Systems, Inc.
+ */
+/*
+ *
+ * Copyright (c) 2001-2017 Cisco Systems, Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following
+ * disclaimer in the documentation and/or other materials provided
+ * with the distribution.
+ *
+ * Neither the name of the Cisco Systems, Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived
+ * from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
+ * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#ifndef SRTP_PRIV_H
+#define SRTP_PRIV_H
+
+// Leave this as the top level import. Ensures the existence of defines
+#include "config.h"
+
+#include "srtp.h"
+#include "rdbx.h"
+#include "rdb.h"
+#include "integers.h"
+#include "cipher.h"
+#include "auth.h"
+#include "aes.h"
+#include "crypto_kernel.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define SRTP_VER_STRING PACKAGE_STRING
+#define SRTP_VERSION PACKAGE_VERSION
+
+typedef struct srtp_stream_ctx_t_ srtp_stream_ctx_t;
+typedef srtp_stream_ctx_t *srtp_stream_t;
+
+/*
+ * the following declarations are libSRTP internal functions
+ */
+
+/*
+ * srtp_get_stream(ssrc) returns a pointer to the stream corresponding
+ * to ssrc, or NULL if no stream exists for that ssrc
+ */
+srtp_stream_t srtp_get_stream(srtp_t srtp, uint32_t ssrc);
+
+/*
+ * srtp_stream_init_keys(s, k) (re)initializes the srtp_stream_t s by
+ * deriving all of the needed keys using the KDF and the key k.
+ */
+srtp_err_status_t srtp_stream_init_keys(srtp_stream_ctx_t *srtp,
+ srtp_master_key_t *master_key,
+ const unsigned int current_mki_index);
+
+/*
+ * srtp_stream_init_all_master_keys(s, k, m) (re)initializes the srtp_stream_t s
+ * by deriving all of the needed keys for all the master keys using the KDF and
+ * the keys from k.
+ */
+srtp_err_status_t srtp_steam_init_all_master_keys(
+ srtp_stream_ctx_t *srtp,
+ unsigned char *key,
+ srtp_master_key_t **keys,
+ const unsigned int max_master_keys);
+
+/*
+ * srtp_stream_init(s, p) initializes the srtp_stream_t s to
+ * use the policy at the location p
+ */
+srtp_err_status_t srtp_stream_init(srtp_stream_t srtp, const srtp_policy_t *p);
+
+/*
+ * libsrtp internal datatypes
+ */
+typedef enum direction_t {
+ dir_unknown = 0,
+ dir_srtp_sender = 1,
+ dir_srtp_receiver = 2
+} direction_t;
+
+/*
+ * srtp_session_keys_t will contain the encryption, hmac, salt keys
+ * for both SRTP and SRTCP. The session keys will also contain the
+ * MKI ID which is used to identify the session keys.
+ */
+typedef struct srtp_session_keys_t {
+ srtp_cipher_t *rtp_cipher;
+ srtp_cipher_t *rtp_xtn_hdr_cipher;
+ srtp_auth_t *rtp_auth;
+ srtp_cipher_t *rtcp_cipher;
+ srtp_auth_t *rtcp_auth;
+ uint8_t salt[SRTP_AEAD_SALT_LEN];
+ uint8_t c_salt[SRTP_AEAD_SALT_LEN];
+ uint8_t *mki_id;
+ unsigned int mki_size;
+ srtp_key_limit_ctx_t *limit;
+} srtp_session_keys_t;
+
+/*
+ * an srtp_stream_t has its own SSRC, encryption key, authentication
+ * key, sequence number, and replay database
+ *
+ * note that the keys might not actually be unique, in which case the
+ * srtp_cipher_t and srtp_auth_t pointers will point to the same structures
+ */
+typedef struct srtp_stream_ctx_t_ {
+ uint32_t ssrc;
+ srtp_session_keys_t *session_keys;
+ unsigned int num_master_keys;
+ srtp_rdbx_t rtp_rdbx;
+ srtp_sec_serv_t rtp_services;
+ srtp_rdb_t rtcp_rdb;
+ srtp_sec_serv_t rtcp_services;
+ direction_t direction;
+ int allow_repeat_tx;
+ int *enc_xtn_hdr;
+ int enc_xtn_hdr_count;
+ uint32_t pending_roc;
+ struct srtp_stream_ctx_t_ *next; /* linked list of streams */
+} strp_stream_ctx_t_;
+
+/*
+ * an srtp_ctx_t holds a stream list and a service description
+ */
+typedef struct srtp_ctx_t_ {
+ struct srtp_stream_ctx_t_ *stream_list; /* linked list of streams */
+ struct srtp_stream_ctx_t_ *stream_template; /* act as template for other */
+ /* streams */
+ void *user_data; /* user custom data */
+} srtp_ctx_t_;
+
+/*
+ * srtp_hdr_t represents an RTP or SRTP header. The bit-fields in
+ * this structure should be declared "unsigned int" instead of
+ * "unsigned char", but doing so causes the MS compiler to not
+ * fully pack the bit fields.
+ *
+ * In this implementation, an srtp_hdr_t is assumed to be 32-bit aligned
+ *
+ * (note that this definition follows that of RFC 1889 Appendix A, but
+ * is not identical)
+ */
+
+#ifndef WORDS_BIGENDIAN
+
+typedef struct {
+ unsigned char cc : 4; /* CSRC count */
+ unsigned char x : 1; /* header extension flag */
+ unsigned char p : 1; /* padding flag */
+ unsigned char version : 2; /* protocol version */
+ unsigned char pt : 7; /* payload type */
+ unsigned char m : 1; /* marker bit */
+ uint16_t seq; /* sequence number */
+ uint32_t ts; /* timestamp */
+ uint32_t ssrc; /* synchronization source */
+} srtp_hdr_t;
+
+#else /* BIG_ENDIAN */
+
+typedef struct {
+ unsigned char version : 2; /* protocol version */
+ unsigned char p : 1; /* padding flag */
+ unsigned char x : 1; /* header extension flag */
+ unsigned char cc : 4; /* CSRC count */
+ unsigned char m : 1; /* marker bit */
+ unsigned char pt : 7; /* payload type */
+ uint16_t seq; /* sequence number */
+ uint32_t ts; /* timestamp */
+ uint32_t ssrc; /* synchronization source */
+} srtp_hdr_t;
+
+#endif
+
+typedef struct {
+ uint16_t profile_specific; /* profile-specific info */
+ uint16_t length; /* number of 32-bit words in extension */
+} srtp_hdr_xtnd_t;
+
+/*
+ * srtcp_hdr_t represents a secure rtcp header
+ *
+ * in this implementation, an srtcp header is assumed to be 32-bit
+ * aligned
+ */
+
+#ifndef WORDS_BIGENDIAN
+
+typedef struct {
+ unsigned char rc : 5; /* reception report count */
+ unsigned char p : 1; /* padding flag */
+ unsigned char version : 2; /* protocol version */
+ unsigned char pt : 8; /* payload type */
+ uint16_t len; /* length */
+ uint32_t ssrc; /* synchronization source */
+} srtcp_hdr_t;
+
+typedef struct {
+ unsigned int index : 31; /* srtcp packet index in network order! */
+ unsigned int e : 1; /* encrypted? 1=yes */
+ /* optional mikey/etc go here */
+ /* and then the variable-length auth tag */
+} srtcp_trailer_t;
+
+#else /* BIG_ENDIAN */
+
+typedef struct {
+ unsigned char version : 2; /* protocol version */
+ unsigned char p : 1; /* padding flag */
+ unsigned char rc : 5; /* reception report count */
+ unsigned char pt : 8; /* payload type */
+ uint16_t len; /* length */
+ uint32_t ssrc; /* synchronization source */
+} srtcp_hdr_t;
+
+typedef struct {
+ unsigned int e : 1; /* encrypted? 1=yes */
+ unsigned int index : 31; /* srtcp packet index */
+ /* optional mikey/etc go here */
+ /* and then the variable-length auth tag */
+} srtcp_trailer_t;
+
+#endif
+
+/*
+ * srtp_handle_event(srtp, srtm, evnt) calls the event handling
+ * function, if there is one.
+ *
+ * This macro is not included in the documentation as it is
+ * an internal-only function.
+ */
+
+#define srtp_handle_event(srtp, strm, evnt) \
+ if (srtp_event_handler) { \
+ srtp_event_data_t data; \
+ data.session = srtp; \
+ data.ssrc = ntohl(strm->ssrc); \
+ data.event = evnt; \
+ srtp_event_handler(&data); \
+ }
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* SRTP_PRIV_H */