/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2008 Doug Rabson
 * 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 <gssapi/gssapi.h>
#include <stdlib.h>
#include <string.h>

#include "utils.h"

OM_uint32
gss_encapsulate_token(const gss_buffer_t input_token, gss_OID oid,
    gss_buffer_t output_token)
{
        unsigned char *p;
        size_t len, inside_len;
        size_t a, b;
        int i;

        _gss_buffer_zero(output_token);

        /*
         * First time around, we calculate the size, second time, we
         * encode the token.
         */
        p = NULL;
        for (i = 0; i < 2; i++) {
                len = 0;

                /*
                 * Token starts with [APPLICATION 0] SEQUENCE.
                 */
                if (p)
                        *p++ = 0x60;
                len++;

                /*
                 * The length embedded in the token is the space
                 * needed for the encapsulated oid plus the length of
                 * the inner token.
                 */
                if (oid->length > 127)
                        return (GSS_S_DEFECTIVE_TOKEN);

                inside_len = 2 + oid->length + input_token->length;

                /*
                 * Figure out how to encode the length
                 */
                if (inside_len < 128) {
                        if (p)
                                *p++ = inside_len;
                        len++;
                } else {
                        b = 1;
                        if (inside_len >= 0x100)
                                b++;
                        if (inside_len >= 0x10000)
                                b++;
                        if (inside_len >= 0x1000000)
                                b++;
                        if (p)
                                *p++ = b | 0x80;
                        len++;
                        a = inside_len << 8*(4 - b);
                        while (b) {
                                if (p)
                                        *p++ = (a >> 24);
                                a <<= 8;
                                len++;
                                b--;
                        }
                }

                /*
                 * Encode the OID for the mechanism. Simplify life by
                 * assuming that the OID length is less than 128 bytes.
                 */
                if (p)
                        *p++ = 0x06;
                len++;
                if (p)
                        *p++ = oid->length;
                len++;
                if (p) {
                        memcpy(p, oid->elements, oid->length);
                        p += oid->length;
                }
                len += oid->length;

                if (p) {
                        memcpy(p, input_token->value, input_token->length);
                        p += input_token->length;
                }
                len += input_token->length;

                if (i == 0) {
                        output_token->length = len;
                        output_token->value = malloc(len);
                        if (!output_token->value)
                                return (GSS_S_DEFECTIVE_TOKEN);
                        p = output_token->value;
                }
        }

        return (GSS_S_COMPLETE);
}