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1b313731 | 1 | /* $OpenBSD: bufbn.c,v 1.5 2007/02/14 14:32:00 stevesk Exp $*/ |
b0a892b2 | 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 | ||
31652869 | 42 | #include <sys/types.h> |
43 | ||
b0a892b2 | 44 | #include <openssl/bn.h> |
00146caa | 45 | |
46 | #include <string.h> | |
31652869 | 47 | #include <stdarg.h> |
00146caa | 48 | |
b0a892b2 | 49 | #include "xmalloc.h" |
31652869 | 50 | #include "buffer.h" |
b0a892b2 | 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 | */ | |
58 | int | |
59 | buffer_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 | ||
88 | void | |
89 | buffer_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 | /* | |
1b313731 | 96 | * Retrieves a BIGNUM from the buffer. |
b0a892b2 | 97 | */ |
98 | int | |
99 | buffer_get_bignum_ret(Buffer *buffer, BIGNUM *value) | |
100 | { | |
101 | u_int bits, bytes; | |
102 | u_char buf[2], *bin; | |
103 | ||
1b313731 | 104 | /* Get the number of bits. */ |
b0a892b2 | 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); | |
e516451d | 121 | if (BN_bin2bn(bin, bytes, value) == NULL) { |
122 | error("buffer_get_bignum_ret: BN_bin2bn failed"); | |
123 | return (-1); | |
124 | } | |
b0a892b2 | 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 | ||
132 | void | |
133 | buffer_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 | /* | |
1b313731 | 140 | * Stores a BIGNUM in the buffer in SSH2 format. |
b0a892b2 | 141 | */ |
142 | int | |
143 | buffer_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 | ||
180 | void | |
181 | buffer_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 | ||
187 | int | |
188 | buffer_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 | } | |
e516451d | 208 | if (BN_bin2bn(bin, len, value) == NULL) { |
209 | error("buffer_get_bignum2_ret: BN_bin2bn failed"); | |
210 | return (-1); | |
211 | } | |
b0a892b2 | 212 | xfree(bin); |
213 | return (0); | |
214 | } | |
215 | ||
216 | void | |
217 | buffer_get_bignum2(Buffer *buffer, BIGNUM *value) | |
218 | { | |
219 | if (buffer_get_bignum2_ret(buffer, value) == -1) | |
220 | fatal("buffer_get_bignum2: buffer error"); | |
221 | } |