bufaux.c revision 98684
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 1.25 2002/04/20 09:14:58 markus Exp $"); 41RCSID("$FreeBSD: head/crypto/openssh/bufaux.c 98684 2002-06-23 16:09:08Z des $"); 42 43#include <openssl/bn.h> 44#include "bufaux.h" 45#include "xmalloc.h" 46#include "getput.h" 47#include "log.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 u_char *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 */ 81void 82buffer_get_bignum(Buffer *buffer, BIGNUM *value) 83{ 84 int bits, bytes; 85 u_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 = buffer_ptr(buffer); 95 BN_bin2bn(bin, bytes, value); 96 buffer_consume(buffer, bytes); 97} 98 99/* 100 * Stores an BIGNUM in the buffer in SSH2 format. 101 */ 102void 103buffer_put_bignum2(Buffer *buffer, BIGNUM *value) 104{ 105 int bytes = BN_num_bytes(value) + 1; 106 u_char *buf = xmalloc(bytes); 107 int oi; 108 int hasnohigh = 0; 109 buf[0] = '\0'; 110 /* Get the value of in binary */ 111 oi = BN_bn2bin(value, buf+1); 112 if (oi != bytes-1) 113 fatal("buffer_put_bignum: BN_bn2bin() failed: oi %d != bin_size %d", 114 oi, bytes); 115 hasnohigh = (buf[1] & 0x80) ? 0 : 1; 116 if (value->neg) { 117 /**XXX should be two's-complement */ 118 int i, carry; 119 u_char *uc = buf; 120 log("negativ!"); 121 for (i = bytes-1, carry = 1; i>=0; i--) { 122 uc[i] ^= 0xff; 123 if (carry) 124 carry = !++uc[i]; 125 } 126 } 127 buffer_put_string(buffer, buf+hasnohigh, bytes-hasnohigh); 128 memset(buf, 0, bytes); 129 xfree(buf); 130} 131 132void 133buffer_get_bignum2(Buffer *buffer, BIGNUM *value) 134{ 135 /**XXX should be two's-complement */ 136 int len; 137 u_char *bin = buffer_get_string(buffer, (u_int *)&len); 138 BN_bin2bn(bin, len, value); 139 xfree(bin); 140} 141/* 142 * Returns integers from the buffer (msb first). 143 */ 144 145u_short 146buffer_get_short(Buffer *buffer) 147{ 148 u_char buf[2]; 149 buffer_get(buffer, (char *) buf, 2); 150 return GET_16BIT(buf); 151} 152 153u_int 154buffer_get_int(Buffer *buffer) 155{ 156 u_char buf[4]; 157 buffer_get(buffer, (char *) buf, 4); 158 return GET_32BIT(buf); 159} 160 161u_int64_t 162buffer_get_int64(Buffer *buffer) 163{ 164 u_char buf[8]; 165 buffer_get(buffer, (char *) buf, 8); 166 return GET_64BIT(buf); 167} 168 169/* 170 * Stores integers in the buffer, msb first. 171 */ 172void 173buffer_put_short(Buffer *buffer, u_short value) 174{ 175 char buf[2]; 176 PUT_16BIT(buf, value); 177 buffer_append(buffer, buf, 2); 178} 179 180void 181buffer_put_int(Buffer *buffer, u_int value) 182{ 183 char buf[4]; 184 PUT_32BIT(buf, value); 185 buffer_append(buffer, buf, 4); 186} 187 188void 189buffer_put_int64(Buffer *buffer, u_int64_t value) 190{ 191 char buf[8]; 192 PUT_64BIT(buf, value); 193 buffer_append(buffer, buf, 8); 194} 195 196/* 197 * Returns an arbitrary binary string from the buffer. The string cannot 198 * be longer than 256k. The returned value points to memory allocated 199 * with xmalloc; it is the responsibility of the calling function to free 200 * the data. If length_ptr is non-NULL, the length of the returned data 201 * will be stored there. A null character will be automatically appended 202 * to the returned string, and is not counted in length. 203 */ 204void * 205buffer_get_string(Buffer *buffer, u_int *length_ptr) 206{ 207 u_int len; 208 u_char *value; 209 /* Get the length. */ 210 len = buffer_get_int(buffer); 211 if (len > 256 * 1024) 212 fatal("buffer_get_string: bad string length %d", len); 213 /* Allocate space for the string. Add one byte for a null character. */ 214 value = xmalloc(len + 1); 215 /* Get the string. */ 216 buffer_get(buffer, value, len); 217 /* Append a null character to make processing easier. */ 218 value[len] = 0; 219 /* Optionally return the length of the string. */ 220 if (length_ptr) 221 *length_ptr = len; 222 return value; 223} 224 225/* 226 * Stores and arbitrary binary string in the buffer. 227 */ 228void 229buffer_put_string(Buffer *buffer, const void *buf, u_int len) 230{ 231 buffer_put_int(buffer, len); 232 buffer_append(buffer, buf, len); 233} 234void 235buffer_put_cstring(Buffer *buffer, const char *s) 236{ 237 if (s == NULL) 238 fatal("buffer_put_cstring: s == NULL"); 239 buffer_put_string(buffer, s, strlen(s)); 240} 241 242/* 243 * Returns a character from the buffer (0 - 255). 244 */ 245int 246buffer_get_char(Buffer *buffer) 247{ 248 char ch; 249 buffer_get(buffer, &ch, 1); 250 return (u_char) ch; 251} 252 253/* 254 * Stores a character in the buffer. 255 */ 256void 257buffer_put_char(Buffer *buffer, int value) 258{ 259 char ch = value; 260 buffer_append(buffer, &ch, 1); 261} 262