/* * 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 "key.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; srtp_ekt_stream_t ekt; 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 * alinged */ #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 */