xref: /freebsd/lib/libgssapi/gss_encapsulate_token.c (revision d0b2dbfa0ecf2bbc9709efc5e20baf8e4b44bbbf)
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 
29 #include <gssapi/gssapi.h>
30 #include <stdlib.h>
31 #include <string.h>
32 
33 #include "utils.h"
34 
35 OM_uint32
36 gss_encapsulate_token(const gss_buffer_t input_token, gss_OID oid,
37     gss_buffer_t output_token)
38 {
39 	unsigned char *p;
40 	size_t len, inside_len;
41 	size_t a, b;
42 	int i;
43 
44 	_gss_buffer_zero(output_token);
45 
46 	/*
47 	 * First time around, we calculate the size, second time, we
48 	 * encode the token.
49 	 */
50 	p = NULL;
51 	for (i = 0; i < 2; i++) {
52 		len = 0;
53 
54 		/*
55 		 * Token starts with [APPLICATION 0] SEQUENCE.
56 		 */
57 		if (p)
58 			*p++ = 0x60;
59 		len++;
60 
61 		/*
62 		 * The length embedded in the token is the space
63 		 * needed for the encapsulated oid plus the length of
64 		 * the inner token.
65 		 */
66 		if (oid->length > 127)
67 			return (GSS_S_DEFECTIVE_TOKEN);
68 
69 		inside_len = 2 + oid->length + input_token->length;
70 
71 		/*
72 		 * Figure out how to encode the length
73 		 */
74 		if (inside_len < 128) {
75 			if (p)
76 				*p++ = inside_len;
77 			len++;
78 		} else {
79 			b = 1;
80 			if (inside_len >= 0x100)
81 				b++;
82 			if (inside_len >= 0x10000)
83 				b++;
84 			if (inside_len >= 0x1000000)
85 				b++;
86 			if (p)
87 				*p++ = b | 0x80;
88 			len++;
89 			a = inside_len << 8*(4 - b);
90 			while (b) {
91 				if (p)
92 					*p++ = (a >> 24);
93 				a <<= 8;
94 				len++;
95 				b--;
96 			}
97 		}
98 
99 		/*
100 		 * Encode the OID for the mechanism. Simplify life by
101 		 * assuming that the OID length is less than 128 bytes.
102 		 */
103 		if (p)
104 			*p++ = 0x06;
105 		len++;
106 		if (p)
107 			*p++ = oid->length;
108 		len++;
109 		if (p) {
110 			memcpy(p, oid->elements, oid->length);
111 			p += oid->length;
112 		}
113 		len += oid->length;
114 
115 		if (p) {
116 			memcpy(p, input_token->value, input_token->length);
117 			p += input_token->length;
118 		}
119 		len += input_token->length;
120 
121 		if (i == 0) {
122 			output_token->length = len;
123 			output_token->value = malloc(len);
124 			if (!output_token->value)
125 				return (GSS_S_DEFECTIVE_TOKEN);
126 			p = output_token->value;
127 		}
128 	}
129 
130 	return (GSS_S_COMPLETE);
131 }
132