/*

 * auth.c

 *

 * some bookkeeping functions for authentication functions

 *

 * 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.

 *

 */

#ifdef HAVE_CONFIG_H

#include <config.h>

#endif

#include "auth.h"

#include "err.h"       /* for srtp_debug */

#include "datatypes.h" /* for octet_string */

/* the debug module for authentiation */

srtp_debug_module_t srtp_mod_auth = {

    false,      /* debugging is off by default */

    "auth func" /* printable name for module   */

};

size_t srtp_auth_get_key_length(const srtp_auth_t *a)

{

    return a->key_len;

}

size_t srtp_auth_get_tag_length(const srtp_auth_t *a)

{

    return a->out_len;

}

size_t srtp_auth_get_prefix_length(const srtp_auth_t *a)

{

    return a->prefix_len;

}

/*

 * srtp_auth_type_test() tests an auth function of type ct against

 * test cases provided in a list test_data of values of key, data, and tag

 * that is known to be good

 */

/* should be big enough for most occasions */

#define SELF_TEST_TAG_BUF_OCTETS 32

srtp_err_status_t srtp_auth_type_test(const srtp_auth_type_t *at,

                                      const srtp_auth_test_case_t *test_data)

{

    const srtp_auth_test_case_t *test_case = test_data;

    srtp_auth_t *a;

    srtp_err_status_t status;

    uint8_t tag[SELF_TEST_TAG_BUF_OCTETS];

    size_t i = 0;

    size_t case_num = 0;

    debug_print(srtp_mod_auth, "running self-test for auth function %s",

                at->description);

    /*

     * check to make sure that we have at least one test case, and

     * return an error if we don't - we need to be paranoid here

     */

    if (test_case == NULL) {

        return srtp_err_status_cant_check;

    }

    /* loop over all test cases */

    while (test_case != NULL) {

        /* check test case parameters */

        if (test_case->tag_length_octets > SELF_TEST_TAG_BUF_OCTETS) {

            return srtp_err_status_bad_param;

        }

        /* allocate auth */

        status = srtp_auth_type_alloc(at, &a, test_case->key_length_octets,

                                      test_case->tag_length_octets);

        if (status) {

            return status;

        }

        /* initialize auth */

        status = srtp_auth_init(a, test_case->key);

        if (status) {

            srtp_auth_dealloc(a);

            return status;

        }

        status = srtp_auth_start(a);

        if (status) {

            srtp_auth_dealloc(a);

            return status;

        }

        /* zeroize tag then compute */

        octet_string_set_to_zero(tag, test_case->tag_length_octets);

        status = srtp_auth_compute(a, test_case->data,

                                   test_case->data_length_octets, tag);

        if (status) {

            srtp_auth_dealloc(a);

            return status;

        }

        debug_print(srtp_mod_auth, "key: %s",

                    srtp_octet_string_hex_string(test_case->key,

                                                 test_case->key_length_octets));

        debug_print(srtp_mod_auth, "data: %s",

                    srtp_octet_string_hex_string(

                        test_case->data, test_case->data_length_octets));

        debug_print(

            srtp_mod_auth, "tag computed: %s",

            srtp_octet_string_hex_string(tag, test_case->tag_length_octets));

        debug_print(srtp_mod_auth, "tag expected: %s",

                    srtp_octet_string_hex_string(test_case->tag,

                                                 test_case->tag_length_octets));

        /* check the result */

        status = srtp_err_status_ok;

        for (i = 0; i < test_case->tag_length_octets; i++) {

            if (tag[i] != test_case->tag[i]) {

                status = srtp_err_status_algo_fail;

                debug_print(srtp_mod_auth, "test case %zu failed", case_num);

                debug_print(srtp_mod_auth, "  (mismatch at octet %zu)", i);

            }

        }

        if (status) {

            srtp_auth_dealloc(a);

            return srtp_err_status_algo_fail;

        }

        /* deallocate the auth function */

        status = srtp_auth_dealloc(a);

        if (status) {

            return status;

        }

        /*

         * the auth function passed the test case, so move on to the next test

         * case in the list; if NULL, we'll quit and return an OK

         */

        test_case = test_case->next_test_case;

        ++case_num;

    }

    return srtp_err_status_ok;

}

/*

 * srtp_auth_type_self_test(at) performs srtp_auth_type_test on at's internal

 * list of test data.

 */

srtp_err_status_t srtp_auth_type_self_test(const srtp_auth_type_t *at)

{

    return srtp_auth_type_test(at, at->test_data);

}