/*      $OpenBSD: radius_msgauth.c,v 1.5 2024/08/14 04:50:31 yasuoka Exp $ */

/*-
 * Copyright (c) 2009 Internet Initiative Japan 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:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE"AUTHOR" 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 AUTHOR 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.
 */

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>

#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <openssl/hmac.h>

#include "radius.h"

#include "radius_local.h"

static int
radius_calc_message_authenticator(RADIUS_PACKET * packet, const char *secret,
    void *ma)
{
        const RADIUS_ATTRIBUTE  *attr;
        const RADIUS_ATTRIBUTE  *end;
        u_char                   zero16[16];
        HMAC_CTX                *ctx;
        int                      mdlen;
        int                      ret = -1;

        memset(zero16, 0, sizeof(zero16));

        if ((ctx = HMAC_CTX_new()) == NULL)
                goto err;

        if (!HMAC_Init_ex(ctx, secret, strlen(secret), EVP_md5(), NULL))
                goto err;

        /*
         * Traverse the radius packet.
         */
        if (packet->request != NULL) {
                if (!HMAC_Update(ctx, (const u_char *)packet->pdata, 4))
                        goto err;
                if (!HMAC_Update(ctx, (unsigned char *)packet->request->pdata
                    ->authenticator, 16))
                        goto err;
        } else {
                if (!HMAC_Update(ctx, (const u_char *)packet->pdata,
                    sizeof(RADIUS_PACKET_DATA)))
                        goto err;
        }

        attr = ATTRS_BEGIN(packet->pdata);
        end = ATTRS_END(packet->pdata);

        for (; attr < end; ATTRS_ADVANCE(attr)) {
                if (attr->type == RADIUS_TYPE_MESSAGE_AUTHENTICATOR) {
                        if (!HMAC_Update(ctx, (u_char *)attr, 2))
                                goto err;
                        if (!HMAC_Update(ctx, (u_char *)zero16, sizeof(zero16)))
                                goto err;
                } else {
                        if (!HMAC_Update(ctx, (u_char *)attr,
                            (int)attr->length))
                                goto err;
                }
        }

        if (!HMAC_Final(ctx, (u_char *)ma, &mdlen))
                goto err;

        ret = 0;

 err:
        HMAC_CTX_free(ctx);

        return (ret);
}

int
radius_put_message_authenticator(RADIUS_PACKET * packet, const char *secret)
{
        u_char   ma[16];

        /*
         * It is not required to initialize ma
         * because content of Message-Authenticator attribute is assumed zero
         * during calculation.
         */
        if (radius_unshift_raw_attr(packet, RADIUS_TYPE_MESSAGE_AUTHENTICATOR,
            ma, sizeof(ma)) != 0)
                return (-1);

        return (radius_set_message_authenticator(packet, secret));
}

int
radius_set_message_authenticator(RADIUS_PACKET * packet, const char *secret)
{
        u_char   ma[16];

        if (radius_calc_message_authenticator(packet, secret, ma) != 0)
                return (-1);

        return (radius_set_raw_attr(packet, RADIUS_TYPE_MESSAGE_AUTHENTICATOR,
            ma, sizeof(ma)));
}

int
radius_check_message_authenticator(RADIUS_PACKET * packet, const char *secret)
{
        int      rval;
        size_t   len;
        u_char   ma0[16], ma1[16];

        if (radius_calc_message_authenticator(packet, secret, ma0) != 0)
                return (-1);

        len = sizeof(ma1);
        if ((rval = radius_get_raw_attr(packet,
                    RADIUS_TYPE_MESSAGE_AUTHENTICATOR, ma1, &len)) != 0)
                return (rval);

        if (len != sizeof(ma1))
                return (-1);

        return (timingsafe_bcmp(ma0, ma1, sizeof(ma1)));
}