224 lines
7.0 KiB
C
224 lines
7.0 KiB
C
/*
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* Asterisk -- An open source telephony toolkit.
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*
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* Copyright (C) 2006 - 2007, Mikael Magnusson
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*
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* Mikael Magnusson <mikma@users.sourceforge.net>
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*
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* See http://www.asterisk.org for more information about
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* the Asterisk project. Please do not directly contact
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* any of the maintainers of this project for assistance;
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* the project provides a web site, mailing lists and IRC
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* channels for your use.
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*
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* This program is free software, distributed under the terms of
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* the GNU General Public License Version 2. See the LICENSE file
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* at the top of the source tree.
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*/
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/*!
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* \file
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*
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* \brief SRTP and SDP Security descriptions
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*
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* Specified in RFC 3711, 6188, 7714, and 4568
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*
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* \author Mikael Magnusson <mikma@users.sourceforge.net>
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*/
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#ifndef _SDP_SRTP_H
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#define _SDP_SRTP_H
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#include "asterisk/linkedlists.h" /* for AST_LIST_ENTRY */
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#include "asterisk/rtp_engine.h" /* for ast_rtp_instance */
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struct ast_sdp_crypto;
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/*! \brief structure for secure RTP audio */
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struct ast_sdp_srtp {
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unsigned int flags;
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struct ast_sdp_crypto *crypto;
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AST_LIST_ENTRY(ast_sdp_srtp) sdp_srtp_list;
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};
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/* SRTP flags */
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#define AST_SRTP_CRYPTO_OFFER_OK (1 << 1)
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#define AST_SRTP_CRYPTO_TAG_32 (1 << 2)
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#define AST_SRTP_CRYPTO_TAG_80 (1 << 3)
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#define AST_SRTP_CRYPTO_TAG_16 (1 << 4)
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#define AST_SRTP_CRYPTO_TAG_8 (1 << 5)
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#define AST_SRTP_CRYPTO_AES_192 (1 << 6)
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#define AST_SRTP_CRYPTO_AES_256 (1 << 7)
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#define AST_SRTP_CRYPTO_OLD_NAME (1 << 8)
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/*!
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* \brief allocate a ast_sdp_srtp structure
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* \return a new malloc'd ast_sdp_srtp structure on success
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* \retval NULL on failure
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*/
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struct ast_sdp_srtp *ast_sdp_srtp_alloc(void);
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/*!
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* \brief free a ast_sdp_srtp structure
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* \param srtp a ast_sdp_srtp structure
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*/
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void ast_sdp_srtp_destroy(struct ast_sdp_srtp *srtp);
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/*! \brief Destroy a previously allocated ast_sdp_crypto struct */
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typedef void (*sdp_crypto_destroy_cb)(struct ast_sdp_crypto *crypto);
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/*!
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* \brief Initialize and return an ast_sdp_crypto struct
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*
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* \details
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* This function allocates a new ast_sdp_crypto struct and initializes its values
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*
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* \retval NULL on failure
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* \return a pointer to a new ast_sdp_crypto structure
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*/
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typedef struct ast_sdp_crypto *(*sdp_crypto_alloc_cb)(void);
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/*!
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* \brief Generate an SRTP a=crypto offer
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*
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* \details
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* The offer is stored on the ast_sdp_crypto struct in a_crypto
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*
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* \param crypto A valid ast_sdp_crypto struct
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* \param taglen Length
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*
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* \retval 0 success
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* \retval nonzero failure
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*/
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typedef int (*sdp_crypto_build_offer_cb)(struct ast_sdp_crypto *crypto, int taglen);
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/*!
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* \brief Parse the a=crypto line from SDP and set appropriate values on the
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* ast_sdp_crypto struct.
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*
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* The attribute line should already have "a=crypto:" removed.
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*
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* \param rtp The rtp instance associated with the SDP being parsed
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* \param srtp SRTP structure
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* \param attr the a:crypto line from SDP
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*
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* \retval 0 success
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* \retval nonzero failure
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*/
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typedef int (*sdp_crypto_parse_offer_cb)(struct ast_rtp_instance *rtp, struct ast_sdp_srtp *srtp, const char *attr);
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/*!
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* \brief Get the crypto attribute line for the srtp structure
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*
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* \details
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* The attribute line does not contain the initial "a=crypto:" and does
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* not terminate with "\r\n".
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*
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* \param srtp The ast_sdp_srtp structure for which to get an attribute line
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* \param dtls_enabled Whether this connection is encrypted with datagram TLS
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* \param default_taglen_32 Whether to default to a tag length of 32 instead of 80
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*
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* \return An attribute line containing cryptographic information
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* \retval NULL if the srtp structure does not require an attribute line containing crypto information
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*/
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typedef const char *(*sdp_srtp_get_attr_cb)(struct ast_sdp_srtp *srtp, int dtls_enabled, int default_taglen_32);
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struct ast_sdp_crypto_api {
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/*! Destroy a crypto struct */
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sdp_crypto_destroy_cb dtor;
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/*! Allocate a crypto struct */
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sdp_crypto_alloc_cb alloc;
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/*! Build a SDP a=crypto offer line parameter string */
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sdp_crypto_build_offer_cb build_offer;
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/*! Parse a SDP a=crypto offer line parameter string */
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sdp_crypto_parse_offer_cb parse_offer;
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/*! Get the SDP a=crypto offer line parameter string */
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sdp_srtp_get_attr_cb get_attr;
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};
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/*!
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* \brief Register SDP SRTP crypto processing routines.
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* \since 14.0.0
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*
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* \param api Callbacks to register.
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*
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* \retval 0 on success.
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* \retval -1 on error.
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*/
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int ast_sdp_crypto_register(struct ast_sdp_crypto_api *api);
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/*!
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* \brief Unregister SDP SRTP crypto processing routines.
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* \since 14.0.0
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*
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* \param api Callbacks to unregister.
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*/
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void ast_sdp_crypto_unregister(struct ast_sdp_crypto_api *api);
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/*! \brief Initialize an return an ast_sdp_crypto struct
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*
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* \details
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* This function allocates a new ast_sdp_crypto struct and initializes its values
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*
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* \retval NULL on failure
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* \return a pointer to a new ast_sdp_crypto structure
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*/
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struct ast_sdp_crypto *ast_sdp_crypto_alloc(void);
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/*! \brief Destroy a previously allocated ast_sdp_crypto struct */
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void ast_sdp_crypto_destroy(struct ast_sdp_crypto *crypto);
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/*! \brief Parse the a=crypto line from SDP and set appropriate values on the
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* ast_sdp_crypto struct.
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*
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* The attribute line should already have "a=crypto:" removed.
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*
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* \param rtp The rtp instance associated with the SDP being parsed
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* \param srtp SRTP structure
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* \param attr the a:crypto line from SDP
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*
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* \retval 0 success
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* \retval nonzero failure
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*/
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int ast_sdp_crypto_process(struct ast_rtp_instance *rtp, struct ast_sdp_srtp *srtp, const char *attr);
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/*! \brief Generate an SRTP a=crypto offer
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*
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* \details
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* The offer is stored on the ast_sdp_crypto struct in a_crypto
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*
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* \param p A valid ast_sdp_crypto struct
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* \param taglen Length
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*
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* \retval 0 success
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* \retval nonzero failure
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*/
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int ast_sdp_crypto_build_offer(struct ast_sdp_crypto *p, int taglen);
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/*! \brief Get the crypto attribute line for the srtp structure
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*
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* The attribute line does not contain the initial "a=crypto:" and does
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* not terminate with "\r\n".
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*
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* \param srtp The ast_sdp_srtp structure for which to get an attribute line
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* \param dtls_enabled Whether this connection is encrypted with datagram TLS
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* \param default_taglen_32 Whether to default to a tag length of 32 instead of 80
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*
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* \return An attribute line containing cryptographic information
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* \retval NULL if the srtp structure does not require an attribute line containing crypto information
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*/
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const char *ast_sdp_srtp_get_attrib(struct ast_sdp_srtp *srtp, int dtls_enabled, int default_taglen_32);
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/*! \brief Get the RTP profile in use by a media session
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*
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* \param sdes_active Whether the media session is using SDES-SRTP
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* \param instance The RTP instance associated with this media session
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* \param using_avpf Whether the media session is using early feedback (AVPF)
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* \param force_avp Force SAVP or SAVPF profile when DTLS is in use
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*
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* \return A non-allocated string describing the profile in use (does not need to be freed)
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*/
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char *ast_sdp_get_rtp_profile(unsigned int sdes_active, struct ast_rtp_instance *instance, unsigned int using_avpf,
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unsigned int force_avp);
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#endif /* _SDP_CRYPTO_H */
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