1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
|
/*
*
* bufaux.c
*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
*
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
* All rights reserved
*
* Created: Wed Mar 29 02:24:47 1995 ylo
*
* Auxiliary functions for storing and retrieving various data types to/from
* Buffers.
*
* SSH2 packet format added by Markus Friedl
*
*/
#include "includes.h"
RCSID("$OpenBSD: bufaux.c,v 1.12 2000/06/20 01:39:39 markus Exp $");
#include "ssh.h"
#include <openssl/bn.h>
#include "bufaux.h"
#include "xmalloc.h"
#include "getput.h"
/*
* Stores an BIGNUM in the buffer with a 2-byte msb first bit count, followed
* by (bits+7)/8 bytes of binary data, msb first.
*/
void
buffer_put_bignum(Buffer *buffer, BIGNUM *value)
{
int bits = BN_num_bits(value);
int bin_size = (bits + 7) / 8;
char unsigned *buf = xmalloc(bin_size);
int oi;
char msg[2];
/* Get the value of in binary */
oi = BN_bn2bin(value, buf);
if (oi != bin_size)
fatal("buffer_put_bignum: BN_bn2bin() failed: oi %d != bin_size %d",
oi, bin_size);
/* Store the number of bits in the buffer in two bytes, msb first. */
PUT_16BIT(msg, bits);
buffer_append(buffer, msg, 2);
/* Store the binary data. */
buffer_append(buffer, (char *)buf, oi);
memset(buf, 0, bin_size);
xfree(buf);
}
/*
* Retrieves an BIGNUM from the buffer.
*/
int
buffer_get_bignum(Buffer *buffer, BIGNUM *value)
{
int bits, bytes;
unsigned char buf[2], *bin;
/* Get the number for bits. */
buffer_get(buffer, (char *) buf, 2);
bits = GET_16BIT(buf);
/* Compute the number of binary bytes that follow. */
bytes = (bits + 7) / 8;
if (buffer_len(buffer) < bytes)
fatal("buffer_get_bignum: input buffer too small");
bin = (unsigned char*) buffer_ptr(buffer);
BN_bin2bn(bin, bytes, value);
buffer_consume(buffer, bytes);
return 2 + bytes;
}
/*
* Stores an BIGNUM in the buffer in SSH2 format.
*/
void
buffer_put_bignum2(Buffer *buffer, BIGNUM *value)
{
int bytes = BN_num_bytes(value) + 1;
unsigned char *buf = xmalloc(bytes);
int oi;
int hasnohigh = 0;
buf[0] = '\0';
/* Get the value of in binary */
oi = BN_bn2bin(value, buf+1);
if (oi != bytes-1)
fatal("buffer_put_bignum: BN_bn2bin() failed: oi %d != bin_size %d",
oi, bytes);
hasnohigh = (buf[1] & 0x80) ? 0 : 1;
if (value->neg) {
/**XXX should be two's-complement */
int i, carry;
unsigned char *uc = buf;
log("negativ!");
for(i = bytes-1, carry = 1; i>=0; i--) {
uc[i] ^= 0xff;
if(carry)
carry = !++uc[i];
}
}
buffer_put_string(buffer, buf+hasnohigh, bytes-hasnohigh);
memset(buf, 0, bytes);
xfree(buf);
}
int
buffer_get_bignum2(Buffer *buffer, BIGNUM *value)
{
/**XXX should be two's-complement */
int len;
unsigned char *bin = (unsigned char *)buffer_get_string(buffer, (unsigned int *)&len);
BN_bin2bn(bin, len, value);
xfree(bin);
return len;
}
/*
* Returns an integer from the buffer (4 bytes, msb first).
*/
unsigned int
buffer_get_int(Buffer *buffer)
{
unsigned char buf[4];
buffer_get(buffer, (char *) buf, 4);
return GET_32BIT(buf);
}
/*
* Stores an integer in the buffer in 4 bytes, msb first.
*/
void
buffer_put_int(Buffer *buffer, unsigned int value)
{
char buf[4];
PUT_32BIT(buf, value);
buffer_append(buffer, buf, 4);
}
/*
* Returns an arbitrary binary string from the buffer. The string cannot
* be longer than 256k. The returned value points to memory allocated
* with xmalloc; it is the responsibility of the calling function to free
* the data. If length_ptr is non-NULL, the length of the returned data
* will be stored there. A null character will be automatically appended
* to the returned string, and is not counted in length.
*/
char *
buffer_get_string(Buffer *buffer, unsigned int *length_ptr)
{
unsigned int len;
char *value;
/* Get the length. */
len = buffer_get_int(buffer);
if (len > 256 * 1024)
fatal("Received packet with bad string length %d", len);
/* Allocate space for the string. Add one byte for a null character. */
value = xmalloc(len + 1);
/* Get the string. */
buffer_get(buffer, value, len);
/* Append a null character to make processing easier. */
value[len] = 0;
/* Optionally return the length of the string. */
if (length_ptr)
*length_ptr = len;
return value;
}
/*
* Stores and arbitrary binary string in the buffer.
*/
void
buffer_put_string(Buffer *buffer, const void *buf, unsigned int len)
{
buffer_put_int(buffer, len);
buffer_append(buffer, buf, len);
}
void
buffer_put_cstring(Buffer *buffer, const char *s)
{
buffer_put_string(buffer, s, strlen(s));
}
/*
* Returns a character from the buffer (0 - 255).
*/
int
buffer_get_char(Buffer *buffer)
{
char ch;
buffer_get(buffer, &ch, 1);
return (unsigned char) ch;
}
/*
* Stores a character in the buffer.
*/
void
buffer_put_char(Buffer *buffer, int value)
{
char ch = value;
buffer_append(buffer, &ch, 1);
}
|
