1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause
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 
37 OM_uint32
38 gss_encapsulate_token(const gss_buffer_t input_token, gss_OID oid,
39     gss_buffer_t output_token)
40 {
41 	unsigned char *p;
42 	size_t len, inside_len;
43 	size_t a, b;
44 	int i;
45 
46 	_gss_buffer_zero(output_token);
47 
48 	/*
49 	 * First time around, we calculate the size, second time, we
50 	 * encode the token.
51 	 */
52 	p = NULL;
53 	for (i = 0; i < 2; i++) {
54 		len = 0;
55 
56 		/*
57 		 * Token starts with [APPLICATION 0] SEQUENCE.
58 		 */
59 		if (p)
60 			*p++ = 0x60;
61 		len++;
62 
63 		/*
64 		 * The length embedded in the token is the space
65 		 * needed for the encapsulated oid plus the length of
66 		 * the inner token.
67 		 */
68 		if (oid->length > 127)
69 			return (GSS_S_DEFECTIVE_TOKEN);
70 
71 		inside_len = 2 + oid->length + input_token->length;
72 
73 		/*
74 		 * Figure out how to encode the length
75 		 */
76 		if (inside_len < 128) {
77 			if (p)
78 				*p++ = inside_len;
79 			len++;
80 		} else {
81 			b = 1;
82 			if (inside_len >= 0x100)
83 				b++;
84 			if (inside_len >= 0x10000)
85 				b++;
86 			if (inside_len >= 0x1000000)
87 				b++;
88 			if (p)
89 				*p++ = b | 0x80;
90 			len++;
91 			a = inside_len << 8*(4 - b);
92 			while (b) {
93 				if (p)
94 					*p++ = (a >> 24);
95 				a <<= 8;
96 				len++;
97 				b--;
98 			}
99 		}
100 
101 		/*
102 		 * Encode the OID for the mechanism. Simplify life by
103 		 * assuming that the OID length is less than 128 bytes.
104 		 */
105 		if (p)
106 			*p++ = 0x06;
107 		len++;
108 		if (p)
109 			*p++ = oid->length;
110 		len++;
111 		if (p) {
112 			memcpy(p, oid->elements, oid->length);
113 			p += oid->length;
114 		}
115 		len += oid->length;
116 
117 		if (p) {
118 			memcpy(p, input_token->value, input_token->length);
119 			p += input_token->length;
120 		}
121 		len += input_token->length;
122 
123 		if (i == 0) {
124 			output_token->length = len;
125 			output_token->value = malloc(len);
126 			if (!output_token->value)
127 				return (GSS_S_DEFECTIVE_TOKEN);
128 			p = output_token->value;
129 		}
130 	}
131 
132 	return (GSS_S_COMPLETE);
133 }
134