bufaux.c

   1 /* $OpenBSD: bufaux.c,v 1.50 2010/08/31 09:58:37 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
  58 int
  59 buffer_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
  69 u_short
  70 buffer_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
  80 int
  81 buffer_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         if (ret != NULL)
  88                 *ret = get_u32(buf);
  89         return (0);
  90 }
  91
  92 u_int
  93 buffer_get_int(Buffer *buffer)
  94 {
  95         u_int ret;
  96
  97         if (buffer_get_int_ret(&ret, buffer) == -1)
  98                 fatal("buffer_get_int: buffer error");
  99
 100         return (ret);
 101 }
 102
 103 int
 104 buffer_get_int64_ret(u_int64_t *ret, Buffer *buffer)
 105 {
 106         u_char buf[8];
 107
 108         if (buffer_get_ret(buffer, (char *) buf, 8) == -1)
 109                 return (-1);
 110         if (ret != NULL)
 111                 *ret = get_u64(buf);
 112         return (0);
 113 }
 114
 115 u_int64_t
 116 buffer_get_int64(Buffer *buffer)
 117 {
 118         u_int64_t ret;
 119
 120         if (buffer_get_int64_ret(&ret, buffer) == -1)
 121                 fatal("buffer_get_int: buffer error");
 122
 123         return (ret);
 124 }
 125
 126 /*
 127  * Stores integers in the buffer, msb first.
 128  */
 129 void
 130 buffer_put_short(Buffer *buffer, u_short value)
 131 {
 132         char buf[2];
 133
 134         put_u16(buf, value);
 135         buffer_append(buffer, buf, 2);
 136 }
 137
 138 void
 139 buffer_put_int(Buffer *buffer, u_int value)
 140 {
 141         char buf[4];
 142
 143         put_u32(buf, value);
 144         buffer_append(buffer, buf, 4);
 145 }
 146
 147 void
 148 buffer_put_int64(Buffer *buffer, u_int64_t value)
 149 {
 150         char buf[8];
 151
 152         put_u64(buf, value);
 153         buffer_append(buffer, buf, 8);
 154 }
 155
 156 /*
 157  * Returns an arbitrary binary string from the buffer.  The string cannot
 158  * be longer than 256k.  The returned value points to memory allocated
 159  * with xmalloc; it is the responsibility of the calling function to free
 160  * the data.  If length_ptr is non-NULL, the length of the returned data
 161  * will be stored there.  A null character will be automatically appended
 162  * to the returned string, and is not counted in length.
 163  */
 164 void *
 165 buffer_get_string_ret(Buffer *buffer, u_int *length_ptr)
 166 {
 167         u_char *value;
 168         u_int len;
 169
 170         /* Get the length. */
 171         if (buffer_get_int_ret(&len, buffer) != 0) {
 172                 error("buffer_get_string_ret: cannot extract length");
 173                 return (NULL);
 174         }
 175         if (len > 256 * 1024) {
 176                 error("buffer_get_string_ret: bad string length %u", len);
 177                 return (NULL);
 178         }
 179         /* Allocate space for the string.  Add one byte for a null character. */
 180         value = xmalloc(len + 1);
 181         /* Get the string. */
 182         if (buffer_get_ret(buffer, value, len) == -1) {
 183                 error("buffer_get_string_ret: buffer_get failed");
 184                 xfree(value);
 185                 return (NULL);
 186         }
 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);
 193 }
 194
 195 void *
 196 buffer_get_string(Buffer *buffer, u_int *length_ptr)
 197 {
 198         void *ret;
 199
 200         if ((ret = buffer_get_string_ret(buffer, length_ptr)) == NULL)
 201                 fatal("buffer_get_string: buffer error");
 202         return (ret);
 203 }
 204
 205 char *
 206 buffer_get_cstring_ret(Buffer *buffer, u_int *length_ptr)
 207 {
 208         u_int length;
 209         char *cp, *ret = buffer_get_string_ret(buffer, &length);
 210
 211         if (ret == NULL)
 212                 return NULL;
 213         if ((cp = memchr(ret, '\0', length)) != NULL) {
 214                 /* XXX allow \0 at end-of-string for a while, remove later */
 215                 if (cp == ret + length - 1)
 216                         error("buffer_get_cstring_ret: string contains \\0");
 217                 else {
 218                         bzero(ret, length);
 219                         xfree(ret);
 220                         return NULL;
 221                 }
 222         }
 223         if (length_ptr != NULL)
 224                 *length_ptr = length;
 225         return ret;
 226 }
 227
 228 char *
 229 buffer_get_cstring(Buffer *buffer, u_int *length_ptr)
 230 {
 231         char *ret;
 232
 233         if ((ret = buffer_get_cstring_ret(buffer, length_ptr)) == NULL)
 234                 fatal("buffer_get_cstring: buffer error");
 235         return ret;
 236 }
 237
 238 void *
 239 buffer_get_string_ptr_ret(Buffer *buffer, u_int *length_ptr)
 240 {
 241         void *ptr;
 242         u_int len;
 243
 244         if (buffer_get_int_ret(&len, buffer) != 0)
 245                 return NULL;
 246         if (len > 256 * 1024) {
 247                 error("buffer_get_string_ptr: bad string length %u", len);
 248                 return NULL;
 249         }
 250         ptr = buffer_ptr(buffer);
 251         buffer_consume(buffer, len);
 252         if (length_ptr)
 253                 *length_ptr = len;
 254         return (ptr);
 255 }
 256
 257 void *
 258 buffer_get_string_ptr(Buffer *buffer, u_int *length_ptr)
 259 {
 260         void *ret;
 261
 262         if ((ret = buffer_get_string_ptr_ret(buffer, length_ptr)) == NULL)
 263                 fatal("buffer_get_string_ptr: buffer error");
 264         return (ret);
 265 }
 266
 267 /*
 268  * Stores and arbitrary binary string in the buffer.
 269  */
 270 void
 271 buffer_put_string(Buffer *buffer, const void *buf, u_int len)
 272 {
 273         buffer_put_int(buffer, len);
 274         buffer_append(buffer, buf, len);
 275 }
 276 void
 277 buffer_put_cstring(Buffer *buffer, const char *s)
 278 {
 279         if (s == NULL)
 280                 fatal("buffer_put_cstring: s == NULL");
 281         buffer_put_string(buffer, s, strlen(s));
 282 }
 283
 284 /*
 285  * Returns a character from the buffer (0 - 255).
 286  */
 287 int
 288 buffer_get_char_ret(char *ret, Buffer *buffer)
 289 {
 290         if (buffer_get_ret(buffer, ret, 1) == -1) {
 291                 error("buffer_get_char_ret: buffer_get_ret failed");
 292                 return (-1);
 293         }
 294         return (0);
 295 }
 296
 297 int
 298 buffer_get_char(Buffer *buffer)
 299 {
 300         char ch;
 301
 302         if (buffer_get_char_ret(&ch, buffer) == -1)
 303                 fatal("buffer_get_char: buffer error");
 304         return (u_char) ch;
 305 }
 306
 307 /*
 308  * Stores a character in the buffer.
 309  */
 310 void
 311 buffer_put_char(Buffer *buffer, int value)
 312 {
 313         char ch = value;
 314
 315         buffer_append(buffer, &ch, 1);
 316 }