blob: 56f4f6d5b19d6af264e5169f946ca62cbf9fe5d5 [file] [log] [blame]
Damien Miller58629fa2006-04-23 12:08:19 +10001/* $OpenBSD: bufbn.c,v 1.1 2006/04/18 10:44:28 dtucker 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 <openssl/bn.h>
43#include "bufaux.h"
44#include "xmalloc.h"
45#include "log.h"
46#include "misc.h"
47
48/*
49 * Stores an BIGNUM in the buffer with a 2-byte msb first bit count, followed
50 * by (bits+7)/8 bytes of binary data, msb first.
51 */
52int
53buffer_put_bignum_ret(Buffer *buffer, const BIGNUM *value)
54{
55 int bits = BN_num_bits(value);
56 int bin_size = (bits + 7) / 8;
57 u_char *buf = xmalloc(bin_size);
58 int oi;
59 char msg[2];
60
61 /* Get the value of in binary */
62 oi = BN_bn2bin(value, buf);
63 if (oi != bin_size) {
64 error("buffer_put_bignum_ret: BN_bn2bin() failed: oi %d != bin_size %d",
65 oi, bin_size);
66 xfree(buf);
67 return (-1);
68 }
69
70 /* Store the number of bits in the buffer in two bytes, msb first. */
71 put_u16(msg, bits);
72 buffer_append(buffer, msg, 2);
73 /* Store the binary data. */
74 buffer_append(buffer, buf, oi);
75
76 memset(buf, 0, bin_size);
77 xfree(buf);
78
79 return (0);
80}
81
82void
83buffer_put_bignum(Buffer *buffer, const BIGNUM *value)
84{
85 if (buffer_put_bignum_ret(buffer, value) == -1)
86 fatal("buffer_put_bignum: buffer error");
87}
88
89/*
90 * Retrieves an BIGNUM from the buffer.
91 */
92int
93buffer_get_bignum_ret(Buffer *buffer, BIGNUM *value)
94{
95 u_int bits, bytes;
96 u_char buf[2], *bin;
97
98 /* Get the number for bits. */
99 if (buffer_get_ret(buffer, (char *) buf, 2) == -1) {
100 error("buffer_get_bignum_ret: invalid length");
101 return (-1);
102 }
103 bits = get_u16(buf);
104 /* Compute the number of binary bytes that follow. */
105 bytes = (bits + 7) / 8;
106 if (bytes > 8 * 1024) {
107 error("buffer_get_bignum_ret: cannot handle BN of size %d", bytes);
108 return (-1);
109 }
110 if (buffer_len(buffer) < bytes) {
111 error("buffer_get_bignum_ret: input buffer too small");
112 return (-1);
113 }
114 bin = buffer_ptr(buffer);
115 BN_bin2bn(bin, bytes, value);
116 if (buffer_consume_ret(buffer, bytes) == -1) {
117 error("buffer_get_bignum_ret: buffer_consume failed");
118 return (-1);
119 }
120 return (0);
121}
122
123void
124buffer_get_bignum(Buffer *buffer, BIGNUM *value)
125{
126 if (buffer_get_bignum_ret(buffer, value) == -1)
127 fatal("buffer_get_bignum: buffer error");
128}
129
130/*
131 * Stores an BIGNUM in the buffer in SSH2 format.
132 */
133int
134buffer_put_bignum2_ret(Buffer *buffer, const BIGNUM *value)
135{
136 u_int bytes;
137 u_char *buf;
138 int oi;
139 u_int hasnohigh = 0;
140
141 if (BN_is_zero(value)) {
142 buffer_put_int(buffer, 0);
143 return 0;
144 }
145 if (value->neg) {
146 error("buffer_put_bignum2_ret: negative numbers not supported");
147 return (-1);
148 }
149 bytes = BN_num_bytes(value) + 1; /* extra padding byte */
150 if (bytes < 2) {
151 error("buffer_put_bignum2_ret: BN too small");
152 return (-1);
153 }
154 buf = xmalloc(bytes);
155 buf[0] = 0x00;
156 /* Get the value of in binary */
157 oi = BN_bn2bin(value, buf+1);
158 if (oi < 0 || (u_int)oi != bytes - 1) {
159 error("buffer_put_bignum2_ret: BN_bn2bin() failed: "
160 "oi %d != bin_size %d", oi, bytes);
161 xfree(buf);
162 return (-1);
163 }
164 hasnohigh = (buf[1] & 0x80) ? 0 : 1;
165 buffer_put_string(buffer, buf+hasnohigh, bytes-hasnohigh);
166 memset(buf, 0, bytes);
167 xfree(buf);
168 return (0);
169}
170
171void
172buffer_put_bignum2(Buffer *buffer, const BIGNUM *value)
173{
174 if (buffer_put_bignum2_ret(buffer, value) == -1)
175 fatal("buffer_put_bignum2: buffer error");
176}
177
178int
179buffer_get_bignum2_ret(Buffer *buffer, BIGNUM *value)
180{
181 u_int len;
182 u_char *bin;
183
184 if ((bin = buffer_get_string_ret(buffer, &len)) == NULL) {
185 error("buffer_get_bignum2_ret: invalid bignum");
186 return (-1);
187 }
188
189 if (len > 0 && (bin[0] & 0x80)) {
190 error("buffer_get_bignum2_ret: negative numbers not supported");
191 xfree(bin);
192 return (-1);
193 }
194 if (len > 8 * 1024) {
195 error("buffer_get_bignum2_ret: cannot handle BN of size %d", len);
196 xfree(bin);
197 return (-1);
198 }
199 BN_bin2bn(bin, len, value);
200 xfree(bin);
201 return (0);
202}
203
204void
205buffer_get_bignum2(Buffer *buffer, BIGNUM *value)
206{
207 if (buffer_get_bignum2_ret(buffer, value) == -1)
208 fatal("buffer_get_bignum2: buffer error");
209}