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00146caa | 1 | /* $OpenBSD: bufbn.c,v 1.2 2006/07/22 20:48:22 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 | ||
42 | #include <openssl/bn.h> | |
00146caa | 43 | |
44 | #include <string.h> | |
45 | ||
b0a892b2 | 46 | #include "bufaux.h" |
47 | #include "xmalloc.h" | |
48 | #include "log.h" | |
49 | #include "misc.h" | |
50 | ||
51 | /* | |
52 | * Stores an BIGNUM in the buffer with a 2-byte msb first bit count, followed | |
53 | * by (bits+7)/8 bytes of binary data, msb first. | |
54 | */ | |
55 | int | |
56 | buffer_put_bignum_ret(Buffer *buffer, const BIGNUM *value) | |
57 | { | |
58 | int bits = BN_num_bits(value); | |
59 | int bin_size = (bits + 7) / 8; | |
60 | u_char *buf = xmalloc(bin_size); | |
61 | int oi; | |
62 | char msg[2]; | |
63 | ||
64 | /* Get the value of in binary */ | |
65 | oi = BN_bn2bin(value, buf); | |
66 | if (oi != bin_size) { | |
67 | error("buffer_put_bignum_ret: BN_bn2bin() failed: oi %d != bin_size %d", | |
68 | oi, bin_size); | |
69 | xfree(buf); | |
70 | return (-1); | |
71 | } | |
72 | ||
73 | /* Store the number of bits in the buffer in two bytes, msb first. */ | |
74 | put_u16(msg, bits); | |
75 | buffer_append(buffer, msg, 2); | |
76 | /* Store the binary data. */ | |
77 | buffer_append(buffer, buf, oi); | |
78 | ||
79 | memset(buf, 0, bin_size); | |
80 | xfree(buf); | |
81 | ||
82 | return (0); | |
83 | } | |
84 | ||
85 | void | |
86 | buffer_put_bignum(Buffer *buffer, const BIGNUM *value) | |
87 | { | |
88 | if (buffer_put_bignum_ret(buffer, value) == -1) | |
89 | fatal("buffer_put_bignum: buffer error"); | |
90 | } | |
91 | ||
92 | /* | |
93 | * Retrieves an BIGNUM from the buffer. | |
94 | */ | |
95 | int | |
96 | buffer_get_bignum_ret(Buffer *buffer, BIGNUM *value) | |
97 | { | |
98 | u_int bits, bytes; | |
99 | u_char buf[2], *bin; | |
100 | ||
101 | /* Get the number for bits. */ | |
102 | if (buffer_get_ret(buffer, (char *) buf, 2) == -1) { | |
103 | error("buffer_get_bignum_ret: invalid length"); | |
104 | return (-1); | |
105 | } | |
106 | bits = get_u16(buf); | |
107 | /* Compute the number of binary bytes that follow. */ | |
108 | bytes = (bits + 7) / 8; | |
109 | if (bytes > 8 * 1024) { | |
110 | error("buffer_get_bignum_ret: cannot handle BN of size %d", bytes); | |
111 | return (-1); | |
112 | } | |
113 | if (buffer_len(buffer) < bytes) { | |
114 | error("buffer_get_bignum_ret: input buffer too small"); | |
115 | return (-1); | |
116 | } | |
117 | bin = buffer_ptr(buffer); | |
118 | BN_bin2bn(bin, bytes, value); | |
119 | if (buffer_consume_ret(buffer, bytes) == -1) { | |
120 | error("buffer_get_bignum_ret: buffer_consume failed"); | |
121 | return (-1); | |
122 | } | |
123 | return (0); | |
124 | } | |
125 | ||
126 | void | |
127 | buffer_get_bignum(Buffer *buffer, BIGNUM *value) | |
128 | { | |
129 | if (buffer_get_bignum_ret(buffer, value) == -1) | |
130 | fatal("buffer_get_bignum: buffer error"); | |
131 | } | |
132 | ||
133 | /* | |
134 | * Stores an BIGNUM in the buffer in SSH2 format. | |
135 | */ | |
136 | int | |
137 | buffer_put_bignum2_ret(Buffer *buffer, const BIGNUM *value) | |
138 | { | |
139 | u_int bytes; | |
140 | u_char *buf; | |
141 | int oi; | |
142 | u_int hasnohigh = 0; | |
143 | ||
144 | if (BN_is_zero(value)) { | |
145 | buffer_put_int(buffer, 0); | |
146 | return 0; | |
147 | } | |
148 | if (value->neg) { | |
149 | error("buffer_put_bignum2_ret: negative numbers not supported"); | |
150 | return (-1); | |
151 | } | |
152 | bytes = BN_num_bytes(value) + 1; /* extra padding byte */ | |
153 | if (bytes < 2) { | |
154 | error("buffer_put_bignum2_ret: BN too small"); | |
155 | return (-1); | |
156 | } | |
157 | buf = xmalloc(bytes); | |
158 | buf[0] = 0x00; | |
159 | /* Get the value of in binary */ | |
160 | oi = BN_bn2bin(value, buf+1); | |
161 | if (oi < 0 || (u_int)oi != bytes - 1) { | |
162 | error("buffer_put_bignum2_ret: BN_bn2bin() failed: " | |
163 | "oi %d != bin_size %d", oi, bytes); | |
164 | xfree(buf); | |
165 | return (-1); | |
166 | } | |
167 | hasnohigh = (buf[1] & 0x80) ? 0 : 1; | |
168 | buffer_put_string(buffer, buf+hasnohigh, bytes-hasnohigh); | |
169 | memset(buf, 0, bytes); | |
170 | xfree(buf); | |
171 | return (0); | |
172 | } | |
173 | ||
174 | void | |
175 | buffer_put_bignum2(Buffer *buffer, const BIGNUM *value) | |
176 | { | |
177 | if (buffer_put_bignum2_ret(buffer, value) == -1) | |
178 | fatal("buffer_put_bignum2: buffer error"); | |
179 | } | |
180 | ||
181 | int | |
182 | buffer_get_bignum2_ret(Buffer *buffer, BIGNUM *value) | |
183 | { | |
184 | u_int len; | |
185 | u_char *bin; | |
186 | ||
187 | if ((bin = buffer_get_string_ret(buffer, &len)) == NULL) { | |
188 | error("buffer_get_bignum2_ret: invalid bignum"); | |
189 | return (-1); | |
190 | } | |
191 | ||
192 | if (len > 0 && (bin[0] & 0x80)) { | |
193 | error("buffer_get_bignum2_ret: negative numbers not supported"); | |
194 | xfree(bin); | |
195 | return (-1); | |
196 | } | |
197 | if (len > 8 * 1024) { | |
198 | error("buffer_get_bignum2_ret: cannot handle BN of size %d", len); | |
199 | xfree(bin); | |
200 | return (-1); | |
201 | } | |
202 | BN_bin2bn(bin, len, value); | |
203 | xfree(bin); | |
204 | return (0); | |
205 | } | |
206 | ||
207 | void | |
208 | buffer_get_bignum2(Buffer *buffer, BIGNUM *value) | |
209 | { | |
210 | if (buffer_get_bignum2_ret(buffer, value) == -1) | |
211 | fatal("buffer_get_bignum2: buffer error"); | |
212 | } |