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Damien Millerd4a8b7e1999-10-27 13:42:43 +10001/*
Damien Miller95def091999-11-25 00:26:21 +11002 * Author: Tatu Ylonen <ylo@cs.hut.fi>
Damien Miller95def091999-11-25 00:26:21 +11003 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
4 * All rights reserved
Damien Miller95def091999-11-25 00:26:21 +11005 * Auxiliary functions for storing and retrieving various data types to/from
6 * Buffers.
7 *
Damien Millere4340be2000-09-16 13:29:08 +11008 * 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".
Damien Millerb38eff82000-04-01 11:09:21 +100013 *
Damien Millere4340be2000-09-16 13:29:08 +110014 *
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.
Damien Miller95def091999-11-25 00:26:21 +110037 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +100038
39#include "includes.h"
Damien Millere4340be2000-09-16 13:29:08 +110040RCSID("$OpenBSD: bufaux.c,v 1.13 2000/09/07 20:27:50 deraadt Exp $");
Damien Millerd4a8b7e1999-10-27 13:42:43 +100041
42#include "ssh.h"
43#include <openssl/bn.h>
Damien Millerd4a8b7e1999-10-27 13:42:43 +100044#include "bufaux.h"
45#include "xmalloc.h"
46#include "getput.h"
47
Damien Miller95def091999-11-25 00:26:21 +110048/*
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 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +100052void
53buffer_put_bignum(Buffer *buffer, BIGNUM *value)
54{
Damien Miller95def091999-11-25 00:26:21 +110055 int bits = BN_num_bits(value);
56 int bin_size = (bits + 7) / 8;
Damien Miller7684ee12000-03-17 23:40:15 +110057 char unsigned *buf = xmalloc(bin_size);
Damien Miller95def091999-11-25 00:26:21 +110058 int oi;
59 char msg[2];
Damien Millerd4a8b7e1999-10-27 13:42:43 +100060
Damien Miller95def091999-11-25 00:26:21 +110061 /* 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. */
Damien Miller7684ee12000-03-17 23:40:15 +110071 buffer_append(buffer, (char *)buf, oi);
Damien Miller5428f641999-11-25 11:54:57 +110072
Damien Miller95def091999-11-25 00:26:21 +110073 memset(buf, 0, bin_size);
74 xfree(buf);
Damien Millerd4a8b7e1999-10-27 13:42:43 +100075}
76
Damien Miller95def091999-11-25 00:26:21 +110077/*
78 * Retrieves an BIGNUM from the buffer.
79 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +100080int
81buffer_get_bignum(Buffer *buffer, BIGNUM *value)
82{
Damien Miller95def091999-11-25 00:26:21 +110083 int bits, bytes;
84 unsigned char buf[2], *bin;
Damien Millerd4a8b7e1999-10-27 13:42:43 +100085
Damien Miller95def091999-11-25 00:26:21 +110086 /* 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");
Damien Miller7684ee12000-03-17 23:40:15 +110093 bin = (unsigned char*) buffer_ptr(buffer);
Damien Miller95def091999-11-25 00:26:21 +110094 BN_bin2bn(bin, bytes, value);
95 buffer_consume(buffer, bytes);
Damien Millerd4a8b7e1999-10-27 13:42:43 +100096
Damien Miller95def091999-11-25 00:26:21 +110097 return 2 + bytes;
Damien Millerd4a8b7e1999-10-27 13:42:43 +100098}
99
Damien Miller95def091999-11-25 00:26:21 +1100100/*
Damien Millerb38eff82000-04-01 11:09:21 +1000101 * Stores an BIGNUM in the buffer in SSH2 format.
102 */
103void
104buffer_put_bignum2(Buffer *buffer, BIGNUM *value)
105{
106 int bytes = BN_num_bytes(value) + 1;
107 unsigned 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 unsigned 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
133int
134buffer_get_bignum2(Buffer *buffer, BIGNUM *value)
135{
136 /**XXX should be two's-complement */
137 int len;
138 unsigned char *bin = (unsigned char *)buffer_get_string(buffer, (unsigned int *)&len);
139 BN_bin2bn(bin, len, value);
140 xfree(bin);
141 return len;
142}
143
144/*
Damien Miller95def091999-11-25 00:26:21 +1100145 * Returns an integer from the buffer (4 bytes, msb first).
146 */
Damien Miller5f056372000-04-16 12:31:48 +1000147unsigned int
Damien Miller95def091999-11-25 00:26:21 +1100148buffer_get_int(Buffer *buffer)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000149{
Damien Miller95def091999-11-25 00:26:21 +1100150 unsigned char buf[4];
151 buffer_get(buffer, (char *) buf, 4);
152 return GET_32BIT(buf);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000153}
154
Damien Miller95def091999-11-25 00:26:21 +1100155/*
156 * Stores an integer in the buffer in 4 bytes, msb first.
157 */
Damien Miller5f056372000-04-16 12:31:48 +1000158void
Damien Miller95def091999-11-25 00:26:21 +1100159buffer_put_int(Buffer *buffer, unsigned int value)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000160{
Damien Miller95def091999-11-25 00:26:21 +1100161 char buf[4];
162 PUT_32BIT(buf, value);
163 buffer_append(buffer, buf, 4);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000164}
165
Damien Miller95def091999-11-25 00:26:21 +1100166/*
167 * Returns an arbitrary binary string from the buffer. The string cannot
168 * be longer than 256k. The returned value points to memory allocated
169 * with xmalloc; it is the responsibility of the calling function to free
170 * the data. If length_ptr is non-NULL, the length of the returned data
171 * will be stored there. A null character will be automatically appended
172 * to the returned string, and is not counted in length.
173 */
174char *
175buffer_get_string(Buffer *buffer, unsigned int *length_ptr)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000176{
Damien Miller95def091999-11-25 00:26:21 +1100177 unsigned int len;
178 char *value;
179 /* Get the length. */
180 len = buffer_get_int(buffer);
181 if (len > 256 * 1024)
182 fatal("Received packet with bad string length %d", len);
183 /* Allocate space for the string. Add one byte for a null character. */
184 value = xmalloc(len + 1);
185 /* Get the string. */
186 buffer_get(buffer, value, len);
187 /* Append a null character to make processing easier. */
188 value[len] = 0;
189 /* Optionally return the length of the string. */
190 if (length_ptr)
191 *length_ptr = len;
192 return value;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000193}
194
Damien Miller95def091999-11-25 00:26:21 +1100195/*
196 * Stores and arbitrary binary string in the buffer.
197 */
Damien Miller5f056372000-04-16 12:31:48 +1000198void
Damien Miller95def091999-11-25 00:26:21 +1100199buffer_put_string(Buffer *buffer, const void *buf, unsigned int len)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000200{
Damien Miller95def091999-11-25 00:26:21 +1100201 buffer_put_int(buffer, len);
202 buffer_append(buffer, buf, len);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000203}
Damien Miller5f056372000-04-16 12:31:48 +1000204void
Damien Millerb38eff82000-04-01 11:09:21 +1000205buffer_put_cstring(Buffer *buffer, const char *s)
206{
207 buffer_put_string(buffer, s, strlen(s));
208}
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000209
Damien Miller95def091999-11-25 00:26:21 +1100210/*
211 * Returns a character from the buffer (0 - 255).
212 */
Damien Miller5f056372000-04-16 12:31:48 +1000213int
Damien Miller95def091999-11-25 00:26:21 +1100214buffer_get_char(Buffer *buffer)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000215{
Damien Miller95def091999-11-25 00:26:21 +1100216 char ch;
217 buffer_get(buffer, &ch, 1);
218 return (unsigned char) ch;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000219}
220
Damien Miller95def091999-11-25 00:26:21 +1100221/*
222 * Stores a character in the buffer.
223 */
Damien Miller5f056372000-04-16 12:31:48 +1000224void
Damien Miller95def091999-11-25 00:26:21 +1100225buffer_put_char(Buffer *buffer, int value)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000226{
Damien Miller95def091999-11-25 00:26:21 +1100227 char ch = value;
228 buffer_append(buffer, &ch, 1);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000229}