bufaux.c revision 65674 
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"
40RCSID("$OpenBSD: bufaux.c,v 1.13 2000/09/07 20:27:50 deraadt Exp $");
41RCSID("$FreeBSD: head/crypto/openssh/bufaux.c 65674 2000-09-10 09:35:38Z kris $");
42
43#include "ssh.h"
44#include <openssl/bn.h>
45#include "bufaux.h"
46#include "xmalloc.h"
47#include "getput.h"
48
49/*
50 * Stores an BIGNUM in the buffer with a 2-byte msb first bit count, followed
51 * by (bits+7)/8 bytes of binary data, msb first.
52 */
53void
54buffer_put_bignum(Buffer *buffer, BIGNUM *value)
55{
56	int bits = BN_num_bits(value);
57	int bin_size = (bits + 7) / 8;
58	char unsigned *buf = xmalloc(bin_size);
59	int oi;
60	char msg[2];
61
62	/* Get the value of in binary */
63	oi = BN_bn2bin(value, buf);
64	if (oi != bin_size)
65		fatal("buffer_put_bignum: BN_bn2bin() failed: oi %d != bin_size %d",
66		      oi, bin_size);
67
68	/* Store the number of bits in the buffer in two bytes, msb first. */
69	PUT_16BIT(msg, bits);
70	buffer_append(buffer, msg, 2);
71	/* Store the binary data. */
72	buffer_append(buffer, (char *)buf, oi);
73
74	memset(buf, 0, bin_size);
75	xfree(buf);
76}
77
78/*
79 * Retrieves an BIGNUM from the buffer.
80 */
81int
82buffer_get_bignum(Buffer *buffer, BIGNUM *value)
83{
84	int bits, bytes;
85	unsigned char buf[2], *bin;
86
87	/* Get the number for bits. */
88	buffer_get(buffer, (char *) buf, 2);
89	bits = GET_16BIT(buf);
90	/* Compute the number of binary bytes that follow. */
91	bytes = (bits + 7) / 8;
92	if (buffer_len(buffer) < bytes)
93		fatal("buffer_get_bignum: input buffer too small");
94	bin = (unsigned char*) buffer_ptr(buffer);
95	BN_bin2bn(bin, bytes, value);
96	buffer_consume(buffer, bytes);
97
98	return 2 + bytes;
99}
100
101/*
102 * Stores an BIGNUM in the buffer in SSH2 format.
103 */
104void
105buffer_put_bignum2(Buffer *buffer, BIGNUM *value)
106{
107	int bytes = BN_num_bytes(value) + 1;
108	unsigned char *buf = xmalloc(bytes);
109	int oi;
110	int hasnohigh = 0;
111	buf[0] = '\0';
112	/* Get the value of in binary */
113	oi = BN_bn2bin(value, buf+1);
114	if (oi != bytes-1)
115		fatal("buffer_put_bignum: BN_bn2bin() failed: oi %d != bin_size %d",
116		      oi, bytes);
117	hasnohigh = (buf[1] & 0x80) ? 0 : 1;
118	if (value->neg) {
119		/**XXX should be two's-complement */
120		int i, carry;
121		unsigned char *uc = buf;
122		log("negativ!");
123		for(i = bytes-1, carry = 1; i>=0; i--) {
124			uc[i] ^= 0xff;
125			if(carry)
126				carry = !++uc[i];
127		}
128	}
129	buffer_put_string(buffer, buf+hasnohigh, bytes-hasnohigh);
130	memset(buf, 0, bytes);
131	xfree(buf);
132}
133
134int
135buffer_get_bignum2(Buffer *buffer, BIGNUM *value)
136{
137	/**XXX should be two's-complement */
138	int len;
139	unsigned char *bin = (unsigned char *)buffer_get_string(buffer, (unsigned int *)&len);
140	BN_bin2bn(bin, len, value);
141	xfree(bin);
142	return len;
143}
144
145/*
146 * Returns an integer from the buffer (4 bytes, msb first).
147 */
148unsigned int
149buffer_get_int(Buffer *buffer)
150{
151	unsigned char buf[4];
152	buffer_get(buffer, (char *) buf, 4);
153	return GET_32BIT(buf);
154}
155
156/*
157 * Stores an integer in the buffer in 4 bytes, msb first.
158 */
159void
160buffer_put_int(Buffer *buffer, unsigned int value)
161{
162	char buf[4];
163	PUT_32BIT(buf, value);
164	buffer_append(buffer, buf, 4);
165}
166
167/*
168 * Returns an arbitrary binary string from the buffer.  The string cannot
169 * be longer than 256k.  The returned value points to memory allocated
170 * with xmalloc; it is the responsibility of the calling function to free
171 * the data.  If length_ptr is non-NULL, the length of the returned data
172 * will be stored there.  A null character will be automatically appended
173 * to the returned string, and is not counted in length.
174 */
175char *
176buffer_get_string(Buffer *buffer, unsigned int *length_ptr)
177{
178	unsigned int len;
179	char *value;
180	/* Get the length. */
181	len = buffer_get_int(buffer);
182	if (len > 256 * 1024)
183		fatal("Received packet with bad string length %d", len);
184	/* Allocate space for the string.  Add one byte for a null character. */
185	value = xmalloc(len + 1);
186	/* Get the string. */
187	buffer_get(buffer, value, len);
188	/* Append a null character to make processing easier. */
189	value[len] = 0;
190	/* Optionally return the length of the string. */
191	if (length_ptr)
192		*length_ptr = len;
193	return value;
194}
195
196/*
197 * Stores and arbitrary binary string in the buffer.
198 */
199void
200buffer_put_string(Buffer *buffer, const void *buf, unsigned int len)
201{
202	buffer_put_int(buffer, len);
203	buffer_append(buffer, buf, len);
204}
205void
206buffer_put_cstring(Buffer *buffer, const char *s)
207{
208	buffer_put_string(buffer, s, strlen(s));
209}
210
211/*
212 * Returns a character from the buffer (0 - 255).
213 */
214int
215buffer_get_char(Buffer *buffer)
216{
217	char ch;
218	buffer_get(buffer, &ch, 1);
219	return (unsigned char) ch;
220}
221
222/*
223 * Stores a character in the buffer.
224 */
225void
226buffer_put_char(Buffer *buffer, int value)
227{
228	char ch = value;
229	buffer_append(buffer, &ch, 1);
230}
231