Refactor code structure for improved readability and maintainability
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343
libsrtp/crypto/hash/hmac_ossl.c
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343
libsrtp/crypto/hash/hmac_ossl.c
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/*
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* hmac_ossl.c
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*
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* Implementation of hmac srtp_auth_type_t that leverages OpenSSL
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*
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* John A. Foley
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* Cisco Systems, Inc.
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*/
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/*
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*
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* Copyright(c) 2013-2017, Cisco Systems, Inc.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* Redistributions in binary form must reproduce the above
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* copyright notice, this list of conditions and the following
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* disclaimer in the documentation and/or other materials provided
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* with the distribution.
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*
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* Neither the name of the Cisco Systems, Inc. nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
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* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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* OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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*/
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif
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#include "auth.h"
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#include "alloc.h"
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#include "err.h" /* for srtp_debug */
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#include "auth_test_cases.h"
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#include <openssl/evp.h>
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#if defined(OPENSSL_VERSION_MAJOR) && (OPENSSL_VERSION_MAJOR >= 3)
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#define SRTP_OSSL_USE_EVP_MAC
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/* before this version reinit of EVP_MAC_CTX was not supported so need to
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* duplicate the CTX each time */
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#define SRTP_OSSL_MIN_REINIT_VERSION 0x30000030L
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#endif
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#ifndef SRTP_OSSL_USE_EVP_MAC
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#include <openssl/hmac.h>
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#endif
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#define SHA1_DIGEST_SIZE 20
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/* the debug module for authentication */
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srtp_debug_module_t srtp_mod_hmac = {
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false, /* debugging is off by default */
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"hmac sha-1 openssl" /* printable name for module */
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};
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/*
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* There are three different behaviors of OpenSSL HMAC for different versions.
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*
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* 1. Pre-3.0 - Use HMAC API
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* 2. 3.0.0 - 3.0.2 - EVP API is required, but doesn't support reinitialization,
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* so we have to use EVP_MAC_CTX_dup
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* 3. 3.0.3 and later - EVP API is required and supports reinitialization
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*
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* The distinction between cases 2 & 3 needs to be made at runtime, because in a
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* shared library context you might end up building against 3.0.3 and running
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* against 3.0.2.
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*/
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typedef struct {
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#ifdef SRTP_OSSL_USE_EVP_MAC
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EVP_MAC *mac;
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EVP_MAC_CTX *ctx;
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int use_dup;
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EVP_MAC_CTX *ctx_dup;
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#else
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HMAC_CTX *ctx;
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#endif
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} srtp_hmac_ossl_ctx_t;
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static srtp_err_status_t srtp_hmac_alloc(srtp_auth_t **a,
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size_t key_len,
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size_t out_len)
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{
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extern const srtp_auth_type_t srtp_hmac;
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srtp_hmac_ossl_ctx_t *hmac;
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debug_print(srtp_mod_hmac, "allocating auth func with key length %zu",
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key_len);
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debug_print(srtp_mod_hmac, " tag length %zu",
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out_len);
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/* check output length - should be less than 20 bytes */
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if (out_len > SHA1_DIGEST_SIZE) {
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return srtp_err_status_bad_param;
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}
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*a = (srtp_auth_t *)srtp_crypto_alloc(sizeof(srtp_auth_t));
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if (*a == NULL) {
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return srtp_err_status_alloc_fail;
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}
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hmac =
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(srtp_hmac_ossl_ctx_t *)srtp_crypto_alloc(sizeof(srtp_hmac_ossl_ctx_t));
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if (hmac == NULL) {
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srtp_crypto_free(*a);
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*a = NULL;
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return srtp_err_status_alloc_fail;
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}
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#ifdef SRTP_OSSL_USE_EVP_MAC
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hmac->mac = EVP_MAC_fetch(NULL, "HMAC", NULL);
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if (hmac->mac == NULL) {
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srtp_crypto_free(hmac);
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srtp_crypto_free(*a);
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*a = NULL;
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return srtp_err_status_alloc_fail;
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}
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hmac->ctx = EVP_MAC_CTX_new(hmac->mac);
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if (hmac->ctx == NULL) {
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EVP_MAC_free(hmac->mac);
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srtp_crypto_free(hmac);
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srtp_crypto_free(*a);
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*a = NULL;
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return srtp_err_status_alloc_fail;
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}
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hmac->use_dup =
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OpenSSL_version_num() < SRTP_OSSL_MIN_REINIT_VERSION ? 1 : 0;
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if (hmac->use_dup) {
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debug_print0(srtp_mod_hmac, "using EVP_MAC_CTX_dup");
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hmac->ctx_dup = hmac->ctx;
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hmac->ctx = NULL;
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}
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#else
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hmac->ctx = HMAC_CTX_new();
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if (hmac->ctx == NULL) {
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srtp_crypto_free(hmac);
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srtp_crypto_free(*a);
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*a = NULL;
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return srtp_err_status_alloc_fail;
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}
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#endif
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/* set pointers */
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(*a)->state = hmac;
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(*a)->type = &srtp_hmac;
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(*a)->out_len = out_len;
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(*a)->key_len = key_len;
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(*a)->prefix_len = 0;
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return srtp_err_status_ok;
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}
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static srtp_err_status_t srtp_hmac_dealloc(srtp_auth_t *a)
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{
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srtp_hmac_ossl_ctx_t *hmac = (srtp_hmac_ossl_ctx_t *)a->state;
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if (hmac) {
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#ifdef SRTP_OSSL_USE_EVP_MAC
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EVP_MAC_CTX_free(hmac->ctx);
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EVP_MAC_CTX_free(hmac->ctx_dup);
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EVP_MAC_free(hmac->mac);
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#else
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HMAC_CTX_free(hmac->ctx);
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#endif
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/* zeroize entire state*/
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octet_string_set_to_zero(hmac, sizeof(srtp_hmac_ossl_ctx_t));
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srtp_crypto_free(hmac);
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}
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/* zeroize entire state*/
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octet_string_set_to_zero(a, sizeof(srtp_auth_t));
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/* free memory */
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srtp_crypto_free(a);
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return srtp_err_status_ok;
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}
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static srtp_err_status_t srtp_hmac_start(void *statev)
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{
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srtp_hmac_ossl_ctx_t *hmac = (srtp_hmac_ossl_ctx_t *)statev;
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#ifdef SRTP_OSSL_USE_EVP_MAC
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if (hmac->use_dup) {
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EVP_MAC_CTX_free(hmac->ctx);
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hmac->ctx = EVP_MAC_CTX_dup(hmac->ctx_dup);
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if (hmac->ctx == NULL) {
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return srtp_err_status_alloc_fail;
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}
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} else {
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if (EVP_MAC_init(hmac->ctx, NULL, 0, NULL) == 0) {
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return srtp_err_status_auth_fail;
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}
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}
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#else
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if (HMAC_Init_ex(hmac->ctx, NULL, 0, NULL, NULL) == 0) {
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return srtp_err_status_auth_fail;
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}
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#endif
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return srtp_err_status_ok;
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}
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static srtp_err_status_t srtp_hmac_init(void *statev,
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const uint8_t *key,
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size_t key_len)
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{
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srtp_hmac_ossl_ctx_t *hmac = (srtp_hmac_ossl_ctx_t *)statev;
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#ifdef SRTP_OSSL_USE_EVP_MAC
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OSSL_PARAM params[2];
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params[0] = OSSL_PARAM_construct_utf8_string("digest", "SHA1", 0);
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params[1] = OSSL_PARAM_construct_end();
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if (EVP_MAC_init(hmac->use_dup ? hmac->ctx_dup : hmac->ctx, key, key_len,
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params) == 0) {
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return srtp_err_status_auth_fail;
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}
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#else
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if (HMAC_Init_ex(hmac->ctx, key, key_len, EVP_sha1(), NULL) == 0) {
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return srtp_err_status_auth_fail;
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}
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#endif
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return srtp_err_status_ok;
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}
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static srtp_err_status_t srtp_hmac_update(void *statev,
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const uint8_t *message,
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size_t msg_octets)
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{
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srtp_hmac_ossl_ctx_t *hmac = (srtp_hmac_ossl_ctx_t *)statev;
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debug_print(srtp_mod_hmac, "input: %s",
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srtp_octet_string_hex_string(message, msg_octets));
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#ifdef SRTP_OSSL_USE_EVP_MAC
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if (EVP_MAC_update(hmac->ctx, message, msg_octets) == 0) {
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return srtp_err_status_auth_fail;
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}
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#else
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if (HMAC_Update(hmac->ctx, message, msg_octets) == 0) {
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return srtp_err_status_auth_fail;
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}
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#endif
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return srtp_err_status_ok;
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}
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static srtp_err_status_t srtp_hmac_compute(void *statev,
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const uint8_t *message,
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size_t msg_octets,
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size_t tag_len,
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uint8_t *result)
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{
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srtp_hmac_ossl_ctx_t *hmac = (srtp_hmac_ossl_ctx_t *)statev;
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uint8_t hash_value[SHA1_DIGEST_SIZE];
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#ifdef SRTP_OSSL_USE_EVP_MAC
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size_t len;
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#else
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unsigned int len;
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#endif
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debug_print(srtp_mod_hmac, "input: %s",
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srtp_octet_string_hex_string(message, msg_octets));
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/* check tag length, return error if we can't provide the value expected */
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if (tag_len > SHA1_DIGEST_SIZE) {
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return srtp_err_status_bad_param;
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}
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/* hash message, copy output into H */
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#ifdef SRTP_OSSL_USE_EVP_MAC
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if (EVP_MAC_update(hmac->ctx, message, msg_octets) == 0) {
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return srtp_err_status_auth_fail;
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}
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if (EVP_MAC_final(hmac->ctx, hash_value, &len, sizeof hash_value) == 0) {
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return srtp_err_status_auth_fail;
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}
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#else
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if (HMAC_Update(hmac->ctx, message, msg_octets) == 0) {
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return srtp_err_status_auth_fail;
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}
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if (HMAC_Final(hmac->ctx, hash_value, &len) == 0) {
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return srtp_err_status_auth_fail;
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}
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#endif
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if (len < tag_len) {
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return srtp_err_status_auth_fail;
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}
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/* copy hash_value to *result */
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for (size_t i = 0; i < tag_len; i++) {
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result[i] = hash_value[i];
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}
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debug_print(srtp_mod_hmac, "output: %s",
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srtp_octet_string_hex_string(hash_value, tag_len));
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return srtp_err_status_ok;
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}
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static const char srtp_hmac_description[] =
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"hmac sha-1 authentication function";
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/*
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* srtp_auth_type_t hmac is the hmac metaobject
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*/
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const srtp_auth_type_t srtp_hmac = {
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srtp_hmac_alloc, /* */
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srtp_hmac_dealloc, /* */
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srtp_hmac_init, /* */
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srtp_hmac_compute, /* */
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srtp_hmac_update, /* */
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srtp_hmac_start, /* */
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srtp_hmac_description, /* */
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&srtp_hmac_test_case_0, /* */
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SRTP_HMAC_SHA1 /* */
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};
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