bufaux.c revision 204917 
1/* $OpenBSD: bufaux.c,v 1.48 2010/02/02 22:49:34 djm Exp $ */
2/*
3 * Author: Tatu Ylonen <ylo@cs.hut.fi>
4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5 *                    All rights reserved
6 * Auxiliary functions for storing and retrieving various data types to/from
7 * Buffers.
8 *
9 * As far as I am concerned, the code I have written for this software
10 * can be used freely for any purpose.  Any derived versions of this
11 * software must be clearly marked as such, and if the derived work is
12 * incompatible with the protocol description in the RFC file, it must be
13 * called by a name other than "ssh" or "Secure Shell".
14 *
15 *
16 * SSH2 packet format added by Markus Friedl
17 * Copyright (c) 2000 Markus Friedl.  All rights reserved.
18 *
19 * Redistribution and use in source and binary forms, with or without
20 * modification, are permitted provided that the following conditions
21 * are met:
22 * 1. Redistributions of source code must retain the above copyright
23 *    notice, this list of conditions and the following disclaimer.
24 * 2. Redistributions in binary form must reproduce the above copyright
25 *    notice, this list of conditions and the following disclaimer in the
26 *    documentation and/or other materials provided with the distribution.
27 *
28 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
29 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
30 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
31 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
33 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
34 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
35 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
36 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
37 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
38 */
39
40#include "includes.h"
41
42#include <sys/types.h>
43
44#include <openssl/bn.h>
45
46#include <string.h>
47#include <stdarg.h>
48
49#include "xmalloc.h"
50#include "buffer.h"
51#include "log.h"
52#include "misc.h"
53
54/*
55 * Returns integers from the buffer (msb first).
56 */
57
58int
59buffer_get_short_ret(u_short *ret, Buffer *buffer)
60{
61	u_char buf[2];
62
63	if (buffer_get_ret(buffer, (char *) buf, 2) == -1)
64		return (-1);
65	*ret = get_u16(buf);
66	return (0);
67}
68
69u_short
70buffer_get_short(Buffer *buffer)
71{
72	u_short ret;
73
74	if (buffer_get_short_ret(&ret, buffer) == -1)
75		fatal("buffer_get_short: buffer error");
76
77	return (ret);
78}
79
80int
81buffer_get_int_ret(u_int *ret, Buffer *buffer)
82{
83	u_char buf[4];
84
85	if (buffer_get_ret(buffer, (char *) buf, 4) == -1)
86		return (-1);
87	*ret = get_u32(buf);
88	return (0);
89}
90
91u_int
92buffer_get_int(Buffer *buffer)
93{
94	u_int ret;
95
96	if (buffer_get_int_ret(&ret, buffer) == -1)
97		fatal("buffer_get_int: buffer error");
98
99	return (ret);
100}
101
102int
103buffer_get_int64_ret(u_int64_t *ret, Buffer *buffer)
104{
105	u_char buf[8];
106
107	if (buffer_get_ret(buffer, (char *) buf, 8) == -1)
108		return (-1);
109	*ret = get_u64(buf);
110	return (0);
111}
112
113u_int64_t
114buffer_get_int64(Buffer *buffer)
115{
116	u_int64_t ret;
117
118	if (buffer_get_int64_ret(&ret, buffer) == -1)
119		fatal("buffer_get_int: buffer error");
120
121	return (ret);
122}
123
124/*
125 * Stores integers in the buffer, msb first.
126 */
127void
128buffer_put_short(Buffer *buffer, u_short value)
129{
130	char buf[2];
131
132	put_u16(buf, value);
133	buffer_append(buffer, buf, 2);
134}
135
136void
137buffer_put_int(Buffer *buffer, u_int value)
138{
139	char buf[4];
140
141	put_u32(buf, value);
142	buffer_append(buffer, buf, 4);
143}
144
145void
146buffer_put_int64(Buffer *buffer, u_int64_t value)
147{
148	char buf[8];
149
150	put_u64(buf, value);
151	buffer_append(buffer, buf, 8);
152}
153
154/*
155 * Returns an arbitrary binary string from the buffer.  The string cannot
156 * be longer than 256k.  The returned value points to memory allocated
157 * with xmalloc; it is the responsibility of the calling function to free
158 * the data.  If length_ptr is non-NULL, the length of the returned data
159 * will be stored there.  A null character will be automatically appended
160 * to the returned string, and is not counted in length.
161 */
162void *
163buffer_get_string_ret(Buffer *buffer, u_int *length_ptr)
164{
165	u_char *value;
166	u_int len;
167
168	/* Get the length. */
169	if (buffer_get_int_ret(&len, buffer) != 0) {
170		error("buffer_get_string_ret: cannot extract length");
171		return (NULL);
172	}
173	if (len > 256 * 1024) {
174		error("buffer_get_string_ret: bad string length %u", len);
175		return (NULL);
176	}
177	/* Allocate space for the string.  Add one byte for a null character. */
178	value = xmalloc(len + 1);
179	/* Get the string. */
180	if (buffer_get_ret(buffer, value, len) == -1) {
181		error("buffer_get_string_ret: buffer_get failed");
182		xfree(value);
183		return (NULL);
184	}
185	/* Append a null character to make processing easier. */
186	value[len] = '\0';
187	/* Optionally return the length of the string. */
188	if (length_ptr)
189		*length_ptr = len;
190	return (value);
191}
192
193void *
194buffer_get_string(Buffer *buffer, u_int *length_ptr)
195{
196	void *ret;
197
198	if ((ret = buffer_get_string_ret(buffer, length_ptr)) == NULL)
199		fatal("buffer_get_string: buffer error");
200	return (ret);
201}
202
203void *
204buffer_get_string_ptr_ret(Buffer *buffer, u_int *length_ptr)
205{
206	void *ptr;
207	u_int len;
208
209	if (buffer_get_int_ret(&len, buffer) != 0)
210		return NULL;
211	if (len > 256 * 1024) {
212		error("buffer_get_string_ptr: bad string length %u", len);
213		return NULL;
214	}
215	ptr = buffer_ptr(buffer);
216	buffer_consume(buffer, len);
217	if (length_ptr)
218		*length_ptr = len;
219	return (ptr);
220}
221
222void *
223buffer_get_string_ptr(Buffer *buffer, u_int *length_ptr)
224{
225	void *ret;
226
227	if ((ret = buffer_get_string_ptr_ret(buffer, length_ptr)) == NULL)
228		fatal("buffer_get_string_ptr: buffer error");
229	return (ret);
230}
231
232/*
233 * Stores and arbitrary binary string in the buffer.
234 */
235void
236buffer_put_string(Buffer *buffer, const void *buf, u_int len)
237{
238	buffer_put_int(buffer, len);
239	buffer_append(buffer, buf, len);
240}
241void
242buffer_put_cstring(Buffer *buffer, const char *s)
243{
244	if (s == NULL)
245		fatal("buffer_put_cstring: s == NULL");
246	buffer_put_string(buffer, s, strlen(s));
247}
248
249/*
250 * Returns a character from the buffer (0 - 255).
251 */
252int
253buffer_get_char_ret(char *ret, Buffer *buffer)
254{
255	if (buffer_get_ret(buffer, ret, 1) == -1) {
256		error("buffer_get_char_ret: buffer_get_ret failed");
257		return (-1);
258	}
259	return (0);
260}
261
262int
263buffer_get_char(Buffer *buffer)
264{
265	char ch;
266
267	if (buffer_get_char_ret(&ch, buffer) == -1)
268		fatal("buffer_get_char: buffer error");
269	return (u_char) ch;
270}
271
272/*
273 * Stores a character in the buffer.
274 */
275void
276buffer_put_char(Buffer *buffer, int value)
277{
278	char ch = value;
279
280	buffer_append(buffer, &ch, 1);
281}
282