blob: 6cf65d372ef60ea8616b89bcad7a701e559083fd [file] [log] [blame]
Damien Millerd7834352006-08-05 12:39:39 +10001/* $OpenBSD: bufbn.c,v 1.3 2006/08/03 03:34:41 deraadt Exp $*/
Damien Miller58629fa2006-04-23 12:08:19 +10002/*
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
Damien Millerd7834352006-08-05 12:39:39 +100042#include <sys/types.h>
43
Damien Miller58629fa2006-04-23 12:08:19 +100044#include <openssl/bn.h>
Damien Millere3476ed2006-07-24 14:13:33 +100045
46#include <string.h>
Damien Millerd7834352006-08-05 12:39:39 +100047#include <stdarg.h>
Damien Millere3476ed2006-07-24 14:13:33 +100048
Damien Miller58629fa2006-04-23 12:08:19 +100049#include "xmalloc.h"
Damien Millerd7834352006-08-05 12:39:39 +100050#include "buffer.h"
Damien Miller58629fa2006-04-23 12:08:19 +100051#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 an 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 for 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 BN_bin2bn(bin, bytes, value);
122 if (buffer_consume_ret(buffer, bytes) == -1) {
123 error("buffer_get_bignum_ret: buffer_consume failed");
124 return (-1);
125 }
126 return (0);
127}
128
129void
130buffer_get_bignum(Buffer *buffer, BIGNUM *value)
131{
132 if (buffer_get_bignum_ret(buffer, value) == -1)
133 fatal("buffer_get_bignum: buffer error");
134}
135
136/*
137 * Stores an BIGNUM in the buffer in SSH2 format.
138 */
139int
140buffer_put_bignum2_ret(Buffer *buffer, const BIGNUM *value)
141{
142 u_int bytes;
143 u_char *buf;
144 int oi;
145 u_int hasnohigh = 0;
146
147 if (BN_is_zero(value)) {
148 buffer_put_int(buffer, 0);
149 return 0;
150 }
151 if (value->neg) {
152 error("buffer_put_bignum2_ret: negative numbers not supported");
153 return (-1);
154 }
155 bytes = BN_num_bytes(value) + 1; /* extra padding byte */
156 if (bytes < 2) {
157 error("buffer_put_bignum2_ret: BN too small");
158 return (-1);
159 }
160 buf = xmalloc(bytes);
161 buf[0] = 0x00;
162 /* Get the value of in binary */
163 oi = BN_bn2bin(value, buf+1);
164 if (oi < 0 || (u_int)oi != bytes - 1) {
165 error("buffer_put_bignum2_ret: BN_bn2bin() failed: "
166 "oi %d != bin_size %d", oi, bytes);
167 xfree(buf);
168 return (-1);
169 }
170 hasnohigh = (buf[1] & 0x80) ? 0 : 1;
171 buffer_put_string(buffer, buf+hasnohigh, bytes-hasnohigh);
172 memset(buf, 0, bytes);
173 xfree(buf);
174 return (0);
175}
176
177void
178buffer_put_bignum2(Buffer *buffer, const BIGNUM *value)
179{
180 if (buffer_put_bignum2_ret(buffer, value) == -1)
181 fatal("buffer_put_bignum2: buffer error");
182}
183
184int
185buffer_get_bignum2_ret(Buffer *buffer, BIGNUM *value)
186{
187 u_int len;
188 u_char *bin;
189
190 if ((bin = buffer_get_string_ret(buffer, &len)) == NULL) {
191 error("buffer_get_bignum2_ret: invalid bignum");
192 return (-1);
193 }
194
195 if (len > 0 && (bin[0] & 0x80)) {
196 error("buffer_get_bignum2_ret: negative numbers not supported");
197 xfree(bin);
198 return (-1);
199 }
200 if (len > 8 * 1024) {
201 error("buffer_get_bignum2_ret: cannot handle BN of size %d", len);
202 xfree(bin);
203 return (-1);
204 }
205 BN_bin2bn(bin, len, value);
206 xfree(bin);
207 return (0);
208}
209
210void
211buffer_get_bignum2(Buffer *buffer, BIGNUM *value)
212{
213 if (buffer_get_bignum2_ret(buffer, value) == -1)
214 fatal("buffer_get_bignum2: buffer error");
215}