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1/* $OpenBSD: bufbn.c,v 1.5 2007/02/14 14:32:00 stevesk Exp $*/
2/*
3 * Author: Tatu Ylonen <ylo@cs.hut.fi>
4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5 * All rights reserved
6 * Auxiliary functions for storing and retrieving various data types to/from
7 * Buffers.
8 *
9 * As far as I am concerned, the code I have written for this software
10 * can be used freely for any purpose. Any derived versions of this
11 * software must be clearly marked as such, and if the derived work is
12 * incompatible with the protocol description in the RFC file, it must be
13 * called by a name other than "ssh" or "Secure Shell".
14 *
15 *
16 * SSH2 packet format added by Markus Friedl
17 * Copyright (c) 2000 Markus Friedl. All rights reserved.
18 *
19 * Redistribution and use in source and binary forms, with or without
20 * modification, are permitted provided that the following conditions
21 * are met:
22 * 1. Redistributions of source code must retain the above copyright
23 * notice, this list of conditions and the following disclaimer.
24 * 2. Redistributions in binary form must reproduce the above copyright
25 * notice, this list of conditions and the following disclaimer in the
26 * documentation and/or other materials provided with the distribution.
27 *
28 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
29 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
30 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
31 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
33 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
34 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
35 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
36 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
37 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
38 */
39
40#include "includes.h"
41
42#include <sys/types.h>
43
44#include <openssl/bn.h>
45
46#include <string.h>
47#include <stdarg.h>
48
49#include "xmalloc.h"
50#include "buffer.h"
51#include "log.h"
52#include "misc.h"
53
54/*
55 * Stores an BIGNUM in the buffer with a 2-byte msb first bit count, followed
56 * by (bits+7)/8 bytes of binary data, msb first.
57 */
58int
59buffer_put_bignum_ret(Buffer *buffer, const BIGNUM *value)
60{
61 int bits = BN_num_bits(value);
62 int bin_size = (bits + 7) / 8;
63 u_char *buf = xmalloc(bin_size);
64 int oi;
65 char msg[2];
66
67 /* Get the value of in binary */
68 oi = BN_bn2bin(value, buf);
69 if (oi != bin_size) {
70 error("buffer_put_bignum_ret: BN_bn2bin() failed: oi %d != bin_size %d",
71 oi, bin_size);
72 xfree(buf);
73 return (-1);
74 }
75
76 /* Store the number of bits in the buffer in two bytes, msb first. */
77 put_u16(msg, bits);
78 buffer_append(buffer, msg, 2);
79 /* Store the binary data. */
80 buffer_append(buffer, buf, oi);
81
82 memset(buf, 0, bin_size);
83 xfree(buf);
84
85 return (0);
86}
87
88void
89buffer_put_bignum(Buffer *buffer, const BIGNUM *value)
90{
91 if (buffer_put_bignum_ret(buffer, value) == -1)
92 fatal("buffer_put_bignum: buffer error");
93}
94
95/*
96 * Retrieves a BIGNUM from the buffer.
97 */
98int
99buffer_get_bignum_ret(Buffer *buffer, BIGNUM *value)
100{
101 u_int bits, bytes;
102 u_char buf[2], *bin;
103
104 /* Get the number of bits. */
105 if (buffer_get_ret(buffer, (char *) buf, 2) == -1) {
106 error("buffer_get_bignum_ret: invalid length");
107 return (-1);
108 }
109 bits = get_u16(buf);
110 /* Compute the number of binary bytes that follow. */
111 bytes = (bits + 7) / 8;
112 if (bytes > 8 * 1024) {
113 error("buffer_get_bignum_ret: cannot handle BN of size %d", bytes);
114 return (-1);
115 }
116 if (buffer_len(buffer) < bytes) {
117 error("buffer_get_bignum_ret: input buffer too small");
118 return (-1);
119 }
120 bin = buffer_ptr(buffer);
121 if (BN_bin2bn(bin, bytes, value) == NULL) {
122 error("buffer_get_bignum_ret: BN_bin2bn failed");
123 return (-1);
124 }
125 if (buffer_consume_ret(buffer, bytes) == -1) {
126 error("buffer_get_bignum_ret: buffer_consume failed");
127 return (-1);
128 }
129 return (0);
130}
131
132void
133buffer_get_bignum(Buffer *buffer, BIGNUM *value)
134{
135 if (buffer_get_bignum_ret(buffer, value) == -1)
136 fatal("buffer_get_bignum: buffer error");
137}
138
139/*
140 * Stores a BIGNUM in the buffer in SSH2 format.
141 */
142int
143buffer_put_bignum2_ret(Buffer *buffer, const BIGNUM *value)
144{
145 u_int bytes;
146 u_char *buf;
147 int oi;
148 u_int hasnohigh = 0;
149
150 if (BN_is_zero(value)) {
151 buffer_put_int(buffer, 0);
152 return 0;
153 }
154 if (value->neg) {
155 error("buffer_put_bignum2_ret: negative numbers not supported");
156 return (-1);
157 }
158 bytes = BN_num_bytes(value) + 1; /* extra padding byte */
159 if (bytes < 2) {
160 error("buffer_put_bignum2_ret: BN too small");
161 return (-1);
162 }
163 buf = xmalloc(bytes);
164 buf[0] = 0x00;
165 /* Get the value of in binary */
166 oi = BN_bn2bin(value, buf+1);
167 if (oi < 0 || (u_int)oi != bytes - 1) {
168 error("buffer_put_bignum2_ret: BN_bn2bin() failed: "
169 "oi %d != bin_size %d", oi, bytes);
170 xfree(buf);
171 return (-1);
172 }
173 hasnohigh = (buf[1] & 0x80) ? 0 : 1;
174 buffer_put_string(buffer, buf+hasnohigh, bytes-hasnohigh);
175 memset(buf, 0, bytes);
176 xfree(buf);
177 return (0);
178}
179
180void
181buffer_put_bignum2(Buffer *buffer, const BIGNUM *value)
182{
183 if (buffer_put_bignum2_ret(buffer, value) == -1)
184 fatal("buffer_put_bignum2: buffer error");
185}
186
187int
188buffer_get_bignum2_ret(Buffer *buffer, BIGNUM *value)
189{
190 u_int len;
191 u_char *bin;
192
193 if ((bin = buffer_get_string_ret(buffer, &len)) == NULL) {
194 error("buffer_get_bignum2_ret: invalid bignum");
195 return (-1);
196 }
197
198 if (len > 0 && (bin[0] & 0x80)) {
199 error("buffer_get_bignum2_ret: negative numbers not supported");
200 xfree(bin);
201 return (-1);
202 }
203 if (len > 8 * 1024) {
204 error("buffer_get_bignum2_ret: cannot handle BN of size %d", len);
205 xfree(bin);
206 return (-1);
207 }
208 if (BN_bin2bn(bin, len, value) == NULL) {
209 error("buffer_get_bignum2_ret: BN_bin2bn failed");
210 return (-1);
211 }
212 xfree(bin);
213 return (0);
214}
215
216void
217buffer_get_bignum2(Buffer *buffer, BIGNUM *value)
218{
219 if (buffer_get_bignum2_ret(buffer, value) == -1)
220 fatal("buffer_get_bignum2: buffer error");
221}