1/*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2008 Doug Rabson
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 *
28 * $FreeBSD$
29 */
30
31#include <gssapi/gssapi.h>
32#include <stdlib.h>
33#include <string.h>
34
35#include "utils.h"
36
37OM_uint32
38gss_decapsulate_token(const gss_buffer_t input_token, gss_OID oid,
39    gss_buffer_t output_token)
40{
41	unsigned char *p = input_token->value;
42	size_t len = input_token->length;
43	size_t a, b;
44	gss_OID_desc mech_oid;
45
46	_gss_buffer_zero(output_token);
47
48	/*
49	 * Token must start with [APPLICATION 0] SEQUENCE.
50	 */
51	if (len == 0 || *p != 0x60)
52		return (GSS_S_DEFECTIVE_TOKEN);
53	p++;
54	len--;
55
56	/*
57	 * Decode the length and make sure it agrees with the
58	 * token length.
59	 */
60	if (len == 0)
61		return (GSS_S_DEFECTIVE_TOKEN);
62	if ((*p & 0x80) == 0) {
63		a = *p;
64		p++;
65		len--;
66	} else {
67		b = *p & 0x7f;
68		p++;
69		len--;
70		if (len < b)
71			return (GSS_S_DEFECTIVE_TOKEN);
72		a = 0;
73		while (b) {
74			a = (a << 8) | *p;
75			p++;
76			len--;
77			b--;
78		}
79	}
80	if (a != len)
81		return (GSS_S_DEFECTIVE_TOKEN);
82
83	/*
84	 * Decode the OID for the mechanism. Simplify life by
85	 * assuming that the OID length is less than 128 bytes.
86	 */
87	if (len < 2 || *p != 0x06)
88		return (GSS_S_DEFECTIVE_TOKEN);
89	if ((p[1] & 0x80) || p[1] > (len - 2))
90		return (GSS_S_DEFECTIVE_TOKEN);
91	mech_oid.length = p[1];
92	p += 2;
93	len -= 2;
94	mech_oid.elements = p;
95
96	if (!gss_oid_equal(&mech_oid, oid))
97		return (GSS_S_FAILURE);
98
99	p += mech_oid.length;
100	len -= mech_oid.length;
101
102	output_token->length = len;
103	output_token->value = malloc(len);
104	if (!output_token->value)
105		return (GSS_S_DEFECTIVE_TOKEN);
106	memcpy(output_token->value, p, len);
107
108	return (GSS_S_COMPLETE);
109}
110