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8efc0c15 | 1 | /* |
6ae2364d | 2 | * |
5260325f | 3 | * bufaux.c |
6ae2364d | 4 | * |
5260325f | 5 | * Author: Tatu Ylonen <ylo@cs.hut.fi> |
6ae2364d | 6 | * |
5260325f | 7 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland |
8 | * All rights reserved | |
6ae2364d | 9 | * |
5260325f | 10 | * Created: Wed Mar 29 02:24:47 1995 ylo |
6ae2364d | 11 | * |
5260325f | 12 | * Auxiliary functions for storing and retrieving various data types to/from |
13 | * Buffers. | |
14 | * | |
7368a6c8 | 15 | * SSH2 packet format added by Markus Friedl |
16 | * | |
5260325f | 17 | */ |
8efc0c15 | 18 | |
19 | #include "includes.h" | |
20 | RCSID("$Id$"); | |
21 | ||
22 | #include "ssh.h" | |
23 | #include <openssl/bn.h> | |
24 | #include "bufaux.h" | |
25 | #include "xmalloc.h" | |
26 | #include "getput.h" | |
27 | ||
5260325f | 28 | /* |
29 | * Stores an BIGNUM in the buffer with a 2-byte msb first bit count, followed | |
30 | * by (bits+7)/8 bytes of binary data, msb first. | |
31 | */ | |
8efc0c15 | 32 | void |
33 | buffer_put_bignum(Buffer *buffer, BIGNUM *value) | |
34 | { | |
5260325f | 35 | int bits = BN_num_bits(value); |
36 | int bin_size = (bits + 7) / 8; | |
610cd5c6 | 37 | char unsigned *buf = xmalloc(bin_size); |
5260325f | 38 | int oi; |
39 | char msg[2]; | |
40 | ||
41 | /* Get the value of in binary */ | |
42 | oi = BN_bn2bin(value, buf); | |
43 | if (oi != bin_size) | |
44 | fatal("buffer_put_bignum: BN_bn2bin() failed: oi %d != bin_size %d", | |
45 | oi, bin_size); | |
46 | ||
47 | /* Store the number of bits in the buffer in two bytes, msb first. */ | |
48 | PUT_16BIT(msg, bits); | |
49 | buffer_append(buffer, msg, 2); | |
50 | /* Store the binary data. */ | |
610cd5c6 | 51 | buffer_append(buffer, (char *)buf, oi); |
aa3378df | 52 | |
5260325f | 53 | memset(buf, 0, bin_size); |
54 | xfree(buf); | |
8efc0c15 | 55 | } |
56 | ||
5260325f | 57 | /* |
58 | * Retrieves an BIGNUM from the buffer. | |
59 | */ | |
8efc0c15 | 60 | int |
61 | buffer_get_bignum(Buffer *buffer, BIGNUM *value) | |
62 | { | |
5260325f | 63 | int bits, bytes; |
64 | unsigned char buf[2], *bin; | |
65 | ||
66 | /* Get the number for bits. */ | |
67 | buffer_get(buffer, (char *) buf, 2); | |
68 | bits = GET_16BIT(buf); | |
69 | /* Compute the number of binary bytes that follow. */ | |
70 | bytes = (bits + 7) / 8; | |
71 | if (buffer_len(buffer) < bytes) | |
72 | fatal("buffer_get_bignum: input buffer too small"); | |
610cd5c6 | 73 | bin = (unsigned char*) buffer_ptr(buffer); |
5260325f | 74 | BN_bin2bn(bin, bytes, value); |
75 | buffer_consume(buffer, bytes); | |
76 | ||
77 | return 2 + bytes; | |
8efc0c15 | 78 | } |
79 | ||
7368a6c8 | 80 | /* |
81 | * Stores an BIGNUM in the buffer in SSH2 format. | |
82 | */ | |
83 | void | |
84 | buffer_put_bignum2(Buffer *buffer, BIGNUM *value) | |
85 | { | |
86 | int bytes = BN_num_bytes(value) + 1; | |
87 | unsigned char *buf = xmalloc(bytes); | |
88 | int oi; | |
89 | int hasnohigh = 0; | |
90 | buf[0] = '\0'; | |
91 | /* Get the value of in binary */ | |
92 | oi = BN_bn2bin(value, buf+1); | |
93 | if (oi != bytes-1) | |
94 | fatal("buffer_put_bignum: BN_bn2bin() failed: oi %d != bin_size %d", | |
95 | oi, bytes); | |
96 | hasnohigh = (buf[1] & 0x80) ? 0 : 1; | |
97 | if (value->neg) { | |
98 | /**XXX should be two's-complement */ | |
99 | int i, carry; | |
100 | unsigned char *uc = buf; | |
101 | log("negativ!"); | |
102 | for(i = bytes-1, carry = 1; i>=0; i--) { | |
103 | uc[i] ^= 0xff; | |
104 | if(carry) | |
105 | carry = !++uc[i]; | |
106 | } | |
107 | } | |
108 | buffer_put_string(buffer, buf+hasnohigh, bytes-hasnohigh); | |
109 | memset(buf, 0, bytes); | |
110 | xfree(buf); | |
111 | } | |
112 | ||
113 | int | |
114 | buffer_get_bignum2(Buffer *buffer, BIGNUM *value) | |
115 | { | |
116 | /**XXX should be two's-complement */ | |
117 | int len; | |
118 | unsigned char *bin = (unsigned char *)buffer_get_string(buffer, (unsigned int *)&len); | |
119 | BN_bin2bn(bin, len, value); | |
120 | xfree(bin); | |
121 | return len; | |
122 | } | |
123 | ||
5260325f | 124 | /* |
125 | * Returns an integer from the buffer (4 bytes, msb first). | |
126 | */ | |
35484284 | 127 | unsigned int |
5260325f | 128 | buffer_get_int(Buffer *buffer) |
8efc0c15 | 129 | { |
5260325f | 130 | unsigned char buf[4]; |
131 | buffer_get(buffer, (char *) buf, 4); | |
132 | return GET_32BIT(buf); | |
8efc0c15 | 133 | } |
134 | ||
5260325f | 135 | /* |
136 | * Stores an integer in the buffer in 4 bytes, msb first. | |
137 | */ | |
35484284 | 138 | void |
5260325f | 139 | buffer_put_int(Buffer *buffer, unsigned int value) |
8efc0c15 | 140 | { |
5260325f | 141 | char buf[4]; |
142 | PUT_32BIT(buf, value); | |
143 | buffer_append(buffer, buf, 4); | |
8efc0c15 | 144 | } |
145 | ||
5260325f | 146 | /* |
147 | * Returns an arbitrary binary string from the buffer. The string cannot | |
148 | * be longer than 256k. The returned value points to memory allocated | |
149 | * with xmalloc; it is the responsibility of the calling function to free | |
150 | * the data. If length_ptr is non-NULL, the length of the returned data | |
151 | * will be stored there. A null character will be automatically appended | |
152 | * to the returned string, and is not counted in length. | |
153 | */ | |
154 | char * | |
155 | buffer_get_string(Buffer *buffer, unsigned int *length_ptr) | |
8efc0c15 | 156 | { |
5260325f | 157 | unsigned int len; |
158 | char *value; | |
159 | /* Get the length. */ | |
160 | len = buffer_get_int(buffer); | |
161 | if (len > 256 * 1024) | |
162 | fatal("Received packet with bad string length %d", len); | |
163 | /* Allocate space for the string. Add one byte for a null character. */ | |
164 | value = xmalloc(len + 1); | |
165 | /* Get the string. */ | |
166 | buffer_get(buffer, value, len); | |
167 | /* Append a null character to make processing easier. */ | |
168 | value[len] = 0; | |
169 | /* Optionally return the length of the string. */ | |
170 | if (length_ptr) | |
171 | *length_ptr = len; | |
172 | return value; | |
8efc0c15 | 173 | } |
174 | ||
5260325f | 175 | /* |
176 | * Stores and arbitrary binary string in the buffer. | |
177 | */ | |
35484284 | 178 | void |
5260325f | 179 | buffer_put_string(Buffer *buffer, const void *buf, unsigned int len) |
8efc0c15 | 180 | { |
5260325f | 181 | buffer_put_int(buffer, len); |
182 | buffer_append(buffer, buf, len); | |
8efc0c15 | 183 | } |
35484284 | 184 | void |
7368a6c8 | 185 | buffer_put_cstring(Buffer *buffer, const char *s) |
186 | { | |
187 | buffer_put_string(buffer, s, strlen(s)); | |
188 | } | |
8efc0c15 | 189 | |
5260325f | 190 | /* |
191 | * Returns a character from the buffer (0 - 255). | |
192 | */ | |
35484284 | 193 | int |
5260325f | 194 | buffer_get_char(Buffer *buffer) |
8efc0c15 | 195 | { |
5260325f | 196 | char ch; |
197 | buffer_get(buffer, &ch, 1); | |
198 | return (unsigned char) ch; | |
8efc0c15 | 199 | } |
200 | ||
5260325f | 201 | /* |
202 | * Stores a character in the buffer. | |
203 | */ | |
35484284 | 204 | void |
5260325f | 205 | buffer_put_char(Buffer *buffer, int value) |
8efc0c15 | 206 | { |
5260325f | 207 | char ch = value; |
208 | buffer_append(buffer, &ch, 1); | |
8efc0c15 | 209 | } |