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1 | /* | |
2 | * Author: Tatu Ylonen <ylo@cs.hut.fi> | |
3 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland | |
4 | * All rights reserved | |
5 | * Auxiliary functions for storing and retrieving various data types to/from | |
6 | * Buffers. | |
7 | * | |
8 | * As far as I am concerned, the code I have written for this software | |
9 | * can be used freely for any purpose. Any derived versions of this | |
10 | * software must be clearly marked as such, and if the derived work is | |
11 | * incompatible with the protocol description in the RFC file, it must be | |
12 | * called by a name other than "ssh" or "Secure Shell". | |
13 | * | |
14 | * | |
15 | * SSH2 packet format added by Markus Friedl | |
16 | * Copyright (c) 2000 Markus Friedl. All rights reserved. | |
17 | * | |
18 | * Redistribution and use in source and binary forms, with or without | |
19 | * modification, are permitted provided that the following conditions | |
20 | * are met: | |
21 | * 1. Redistributions of source code must retain the above copyright | |
22 | * notice, this list of conditions and the following disclaimer. | |
23 | * 2. Redistributions in binary form must reproduce the above copyright | |
24 | * notice, this list of conditions and the following disclaimer in the | |
25 | * documentation and/or other materials provided with the distribution. | |
26 | * | |
27 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR | |
28 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
29 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | |
30 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | |
31 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
32 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
33 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
34 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
35 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | |
36 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
37 | */ | |
38 | ||
39 | #include "includes.h" | |
40 | RCSID("$OpenBSD: bufaux.c,v 1.15 2001/01/10 22:56:22 markus Exp $"); | |
41 | ||
42 | #include "ssh.h" | |
43 | #include <openssl/bn.h> | |
44 | #include "bufaux.h" | |
45 | #include "xmalloc.h" | |
46 | #include "getput.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 | */ | |
52 | void | |
53 | buffer_put_bignum(Buffer *buffer, 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 | fatal("buffer_put_bignum: BN_bn2bin() failed: oi %d != bin_size %d", | |
65 | oi, bin_size); | |
66 | ||
67 | /* Store the number of bits in the buffer in two bytes, msb first. */ | |
68 | PUT_16BIT(msg, bits); | |
69 | buffer_append(buffer, msg, 2); | |
70 | /* Store the binary data. */ | |
71 | buffer_append(buffer, (char *)buf, oi); | |
72 | ||
73 | memset(buf, 0, bin_size); | |
74 | xfree(buf); | |
75 | } | |
76 | ||
77 | /* | |
78 | * Retrieves an BIGNUM from the buffer. | |
79 | */ | |
80 | int | |
81 | buffer_get_bignum(Buffer *buffer, BIGNUM *value) | |
82 | { | |
83 | int bits, bytes; | |
84 | u_char buf[2], *bin; | |
85 | ||
86 | /* Get the number for bits. */ | |
87 | buffer_get(buffer, (char *) buf, 2); | |
88 | bits = GET_16BIT(buf); | |
89 | /* Compute the number of binary bytes that follow. */ | |
90 | bytes = (bits + 7) / 8; | |
91 | if (buffer_len(buffer) < bytes) | |
92 | fatal("buffer_get_bignum: input buffer too small"); | |
93 | bin = (u_char*) buffer_ptr(buffer); | |
94 | BN_bin2bn(bin, bytes, value); | |
95 | buffer_consume(buffer, bytes); | |
96 | ||
97 | return 2 + bytes; | |
98 | } | |
99 | ||
100 | /* | |
101 | * Stores an BIGNUM in the buffer in SSH2 format. | |
102 | */ | |
103 | void | |
104 | buffer_put_bignum2(Buffer *buffer, BIGNUM *value) | |
105 | { | |
106 | int bytes = BN_num_bytes(value) + 1; | |
107 | u_char *buf = xmalloc(bytes); | |
108 | int oi; | |
109 | int hasnohigh = 0; | |
110 | buf[0] = '\0'; | |
111 | /* Get the value of in binary */ | |
112 | oi = BN_bn2bin(value, buf+1); | |
113 | if (oi != bytes-1) | |
114 | fatal("buffer_put_bignum: BN_bn2bin() failed: oi %d != bin_size %d", | |
115 | oi, bytes); | |
116 | hasnohigh = (buf[1] & 0x80) ? 0 : 1; | |
117 | if (value->neg) { | |
118 | /**XXX should be two's-complement */ | |
119 | int i, carry; | |
120 | u_char *uc = buf; | |
121 | log("negativ!"); | |
122 | for(i = bytes-1, carry = 1; i>=0; i--) { | |
123 | uc[i] ^= 0xff; | |
124 | if(carry) | |
125 | carry = !++uc[i]; | |
126 | } | |
127 | } | |
128 | buffer_put_string(buffer, buf+hasnohigh, bytes-hasnohigh); | |
129 | memset(buf, 0, bytes); | |
130 | xfree(buf); | |
131 | } | |
132 | ||
133 | int | |
134 | buffer_get_bignum2(Buffer *buffer, BIGNUM *value) | |
135 | { | |
136 | /**XXX should be two's-complement */ | |
137 | int len; | |
138 | u_char *bin = (u_char *)buffer_get_string(buffer, (u_int *)&len); | |
139 | BN_bin2bn(bin, len, value); | |
140 | xfree(bin); | |
141 | return len; | |
142 | } | |
143 | ||
144 | /* | |
145 | * Returns an integer from the buffer (4 bytes, msb first). | |
146 | */ | |
147 | u_int | |
148 | buffer_get_int(Buffer *buffer) | |
149 | { | |
150 | u_char buf[4]; | |
151 | buffer_get(buffer, (char *) buf, 4); | |
152 | return GET_32BIT(buf); | |
153 | } | |
154 | ||
155 | u_int64_t | |
156 | buffer_get_int64(Buffer *buffer) | |
157 | { | |
158 | u_char buf[8]; | |
159 | buffer_get(buffer, (char *) buf, 8); | |
160 | return GET_64BIT(buf); | |
161 | } | |
162 | ||
163 | /* | |
164 | * Stores an integer in the buffer in 4 bytes, msb first. | |
165 | */ | |
166 | void | |
167 | buffer_put_int(Buffer *buffer, u_int value) | |
168 | { | |
169 | char buf[4]; | |
170 | PUT_32BIT(buf, value); | |
171 | buffer_append(buffer, buf, 4); | |
172 | } | |
173 | ||
174 | void | |
175 | buffer_put_int64(Buffer *buffer, u_int64_t value) | |
176 | { | |
177 | char buf[8]; | |
178 | PUT_64BIT(buf, value); | |
179 | buffer_append(buffer, buf, 8); | |
180 | } | |
181 | ||
182 | /* | |
183 | * Returns an arbitrary binary string from the buffer. The string cannot | |
184 | * be longer than 256k. The returned value points to memory allocated | |
185 | * with xmalloc; it is the responsibility of the calling function to free | |
186 | * the data. If length_ptr is non-NULL, the length of the returned data | |
187 | * will be stored there. A null character will be automatically appended | |
188 | * to the returned string, and is not counted in length. | |
189 | */ | |
190 | char * | |
191 | buffer_get_string(Buffer *buffer, u_int *length_ptr) | |
192 | { | |
193 | u_int len; | |
194 | char *value; | |
195 | /* Get the length. */ | |
196 | len = buffer_get_int(buffer); | |
197 | if (len > 256 * 1024) | |
198 | fatal("Received packet with bad string length %d", len); | |
199 | /* Allocate space for the string. Add one byte for a null character. */ | |
200 | value = xmalloc(len + 1); | |
201 | /* Get the string. */ | |
202 | buffer_get(buffer, value, len); | |
203 | /* Append a null character to make processing easier. */ | |
204 | value[len] = 0; | |
205 | /* Optionally return the length of the string. */ | |
206 | if (length_ptr) | |
207 | *length_ptr = len; | |
208 | return value; | |
209 | } | |
210 | ||
211 | /* | |
212 | * Stores and arbitrary binary string in the buffer. | |
213 | */ | |
214 | void | |
215 | buffer_put_string(Buffer *buffer, const void *buf, u_int len) | |
216 | { | |
217 | buffer_put_int(buffer, len); | |
218 | buffer_append(buffer, buf, len); | |
219 | } | |
220 | void | |
221 | buffer_put_cstring(Buffer *buffer, const char *s) | |
222 | { | |
223 | buffer_put_string(buffer, s, strlen(s)); | |
224 | } | |
225 | ||
226 | /* | |
227 | * Returns a character from the buffer (0 - 255). | |
228 | */ | |
229 | int | |
230 | buffer_get_char(Buffer *buffer) | |
231 | { | |
232 | char ch; | |
233 | buffer_get(buffer, &ch, 1); | |
234 | return (u_char) ch; | |
235 | } | |
236 | ||
237 | /* | |
238 | * Stores a character in the buffer. | |
239 | */ | |
240 | void | |
241 | buffer_put_char(Buffer *buffer, int value) | |
242 | { | |
243 | char ch = value; | |
244 | buffer_append(buffer, &ch, 1); | |
245 | } |