bufaux.c revision 98941
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 $"); 41 42#include <openssl/bn.h> 43#include "bufaux.h" 44#include "xmalloc.h" 45#include "getput.h" 46#include "log.h" 47 48/* 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 */ 52void 53buffer_put_bignum(Buffer *buffer, BIGNUM *value) 54{ 55 int bits = BN_num_bits(value); 56 int bin_size = (bits + 7) / 8; 57 u_char *buf = xmalloc(bin_size); 58 int oi; 59 char msg[2]; 60 61 /* 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. */ 71 buffer_append(buffer, (char *)buf, oi); 72 73 memset(buf, 0, bin_size); 74 xfree(buf); 75} 76 77/* 78 * Retrieves an BIGNUM from the buffer. 79 */ 80void 81buffer_get_bignum(Buffer *buffer, BIGNUM *value) 82{ 83 int bits, bytes; 84 u_char buf[2], *bin; 85 86 /* 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"); 93 bin = buffer_ptr(buffer); 94 BN_bin2bn(bin, bytes, value); 95 buffer_consume(buffer, bytes); 96} 97 98/* 99 * Stores an BIGNUM in the buffer in SSH2 format. 100 */ 101void 102buffer_put_bignum2(Buffer *buffer, BIGNUM *value) 103{ 104 int bytes = BN_num_bytes(value) + 1; 105 u_char *buf = xmalloc(bytes); 106 int oi; 107 int hasnohigh = 0; 108 buf[0] = '\0'; 109 /* Get the value of in binary */ 110 oi = BN_bn2bin(value, buf+1); 111 if (oi != bytes-1) 112 fatal("buffer_put_bignum: BN_bn2bin() failed: oi %d != bin_size %d", 113 oi, bytes); 114 hasnohigh = (buf[1] & 0x80) ? 0 : 1; 115 if (value->neg) { 116 /**XXX should be two's-complement */ 117 int i, carry; 118 u_char *uc = buf; 119 log("negativ!"); 120 for (i = bytes-1, carry = 1; i>=0; i--) { 121 uc[i] ^= 0xff; 122 if (carry) 123 carry = !++uc[i]; 124 } 125 } 126 buffer_put_string(buffer, buf+hasnohigh, bytes-hasnohigh); 127 memset(buf, 0, bytes); 128 xfree(buf); 129} 130 131void 132buffer_get_bignum2(Buffer *buffer, BIGNUM *value) 133{ 134 /**XXX should be two's-complement */ 135 int len; 136 u_char *bin = buffer_get_string(buffer, (u_int *)&len); 137 BN_bin2bn(bin, len, value); 138 xfree(bin); 139} 140/* 141 * Returns integers from the buffer (msb first). 142 */ 143 144u_short 145buffer_get_short(Buffer *buffer) 146{ 147 u_char buf[2]; 148 buffer_get(buffer, (char *) buf, 2); 149 return GET_16BIT(buf); 150} 151 152u_int 153buffer_get_int(Buffer *buffer) 154{ 155 u_char buf[4]; 156 buffer_get(buffer, (char *) buf, 4); 157 return GET_32BIT(buf); 158} 159 160#ifdef HAVE_U_INT64_T 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#endif 169 170/* 171 * Stores integers in the buffer, msb first. 172 */ 173void 174buffer_put_short(Buffer *buffer, u_short value) 175{ 176 char buf[2]; 177 PUT_16BIT(buf, value); 178 buffer_append(buffer, buf, 2); 179} 180 181void 182buffer_put_int(Buffer *buffer, u_int value) 183{ 184 char buf[4]; 185 PUT_32BIT(buf, value); 186 buffer_append(buffer, buf, 4); 187} 188 189#ifdef HAVE_U_INT64_T 190void 191buffer_put_int64(Buffer *buffer, u_int64_t value) 192{ 193 char buf[8]; 194 PUT_64BIT(buf, value); 195 buffer_append(buffer, buf, 8); 196} 197#endif 198 199/* 200 * Returns an arbitrary binary string from the buffer. The string cannot 201 * be longer than 256k. The returned value points to memory allocated 202 * with xmalloc; it is the responsibility of the calling function to free 203 * the data. If length_ptr is non-NULL, the length of the returned data 204 * will be stored there. A null character will be automatically appended 205 * to the returned string, and is not counted in length. 206 */ 207void * 208buffer_get_string(Buffer *buffer, u_int *length_ptr) 209{ 210 u_int len; 211 u_char *value; 212 /* Get the length. */ 213 len = buffer_get_int(buffer); 214 if (len > 256 * 1024) 215 fatal("buffer_get_string: bad string length %d", len); 216 /* Allocate space for the string. Add one byte for a null character. */ 217 value = xmalloc(len + 1); 218 /* Get the string. */ 219 buffer_get(buffer, value, len); 220 /* Append a null character to make processing easier. */ 221 value[len] = 0; 222 /* Optionally return the length of the string. */ 223 if (length_ptr) 224 *length_ptr = len; 225 return value; 226} 227 228/* 229 * Stores and arbitrary binary string in the buffer. 230 */ 231void 232buffer_put_string(Buffer *buffer, const void *buf, u_int len) 233{ 234 buffer_put_int(buffer, len); 235 buffer_append(buffer, buf, len); 236} 237void 238buffer_put_cstring(Buffer *buffer, const char *s) 239{ 240 if (s == NULL) 241 fatal("buffer_put_cstring: s == NULL"); 242 buffer_put_string(buffer, s, strlen(s)); 243} 244 245/* 246 * Returns a character from the buffer (0 - 255). 247 */ 248int 249buffer_get_char(Buffer *buffer) 250{ 251 char ch; 252 buffer_get(buffer, &ch, 1); 253 return (u_char) ch; 254} 255 256/* 257 * Stores a character in the buffer. 258 */ 259void 260buffer_put_char(Buffer *buffer, int value) 261{ 262 char ch = value; 263 buffer_append(buffer, &ch, 1); 264} 265