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/* $OpenBSD: bufbn.c,v 1.11 2014/02/27 08:25:09 djm Exp $*/
/*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
* All rights reserved
* Auxiliary functions for storing and retrieving various data types to/from
* Buffers.
*
* As far as I am concerned, the code I have written for this software
* can be used freely for any purpose. Any derived versions of this
* software must be clearly marked as such, and if the derived work is
* incompatible with the protocol description in the RFC file, it must be
* called by a name other than "ssh" or "Secure Shell".
*
*
* SSH2 packet format added by Markus Friedl
* Copyright (c) 2000 Markus Friedl. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "includes.h"
#include <sys/types.h>
#include <openssl/bn.h>
#include <string.h>
#include <stdarg.h>
#include <stdlib.h>
#include "xmalloc.h"
#include "buffer.h"
#include "log.h"
#include "misc.h"
/*
* Stores an BIGNUM in the buffer with a 2-byte msb first bit count, followed
* by (bits+7)/8 bytes of binary data, msb first.
*/
int
buffer_put_bignum_ret(Buffer *buffer, const BIGNUM *value)
{
int bits = BN_num_bits(value);
int bin_size = (bits + 7) / 8;
u_char *buf = xmalloc(bin_size);
int oi;
char msg[2];
/* Get the value of in binary */
oi = BN_bn2bin(value, buf);
if (oi != bin_size) {
error("buffer_put_bignum_ret: BN_bn2bin() failed: oi %d != bin_size %d",
oi, bin_size);
free(buf);
return (-1);
}
/* Store the number of bits in the buffer in two bytes, msb first. */
put_u16(msg, bits);
buffer_append(buffer, msg, 2);
/* Store the binary data. */
buffer_append(buffer, buf, oi);
explicit_bzero(buf, bin_size);
free(buf);
return (0);
}
void
buffer_put_bignum(Buffer *buffer, const BIGNUM *value)
{
if (buffer_put_bignum_ret(buffer, value) == -1)
fatal("buffer_put_bignum: buffer error");
}
/*
* Retrieves a BIGNUM from the buffer.
*/
int
buffer_get_bignum_ret(Buffer *buffer, BIGNUM *value)
{
u_int bits, bytes;
u_char buf[2], *bin;
/* Get the number of bits. */
if (buffer_get_ret(buffer, (char *) buf, 2) == -1) {
error("buffer_get_bignum_ret: invalid length");
return (-1);
}
bits = get_u16(buf);
if (bits > 65535-7) {
error("buffer_get_bignum_ret: cannot handle BN of size %d",
bits);
return (-1);
}
/* Compute the number of binary bytes that follow. */
bytes = (bits + 7) / 8;
if (bytes > 8 * 1024) {
error("buffer_get_bignum_ret: cannot handle BN of size %d", bytes);
return (-1);
}
if (buffer_len(buffer) < bytes) {
error("buffer_get_bignum_ret: input buffer too small");
return (-1);
}
bin = buffer_ptr(buffer);
if (BN_bin2bn(bin, bytes, value) == NULL) {
error("buffer_get_bignum_ret: BN_bin2bn failed");
return (-1);
}
if (buffer_consume_ret(buffer, bytes) == -1) {
error("buffer_get_bignum_ret: buffer_consume failed");
return (-1);
}
return (0);
}
void
buffer_get_bignum(Buffer *buffer, BIGNUM *value)
{
if (buffer_get_bignum_ret(buffer, value) == -1)
fatal("buffer_get_bignum: buffer error");
}
/*
* Stores a BIGNUM in the buffer in SSH2 format.
*/
int
buffer_put_bignum2_ret(Buffer *buffer, const BIGNUM *value)
{
u_int bytes;
u_char *buf;
int oi;
u_int hasnohigh = 0;
if (BN_is_zero(value)) {
buffer_put_int(buffer, 0);
return 0;
}
if (value->neg) {
error("buffer_put_bignum2_ret: negative numbers not supported");
return (-1);
}
bytes = BN_num_bytes(value) + 1; /* extra padding byte */
if (bytes < 2) {
error("buffer_put_bignum2_ret: BN too small");
return (-1);
}
buf = xmalloc(bytes);
buf[0] = 0x00;
/* Get the value of in binary */
oi = BN_bn2bin(value, buf+1);
if (oi < 0 || (u_int)oi != bytes - 1) {
error("buffer_put_bignum2_ret: BN_bn2bin() failed: "
"oi %d != bin_size %d", oi, bytes);
free(buf);
return (-1);
}
hasnohigh = (buf[1] & 0x80) ? 0 : 1;
buffer_put_string(buffer, buf+hasnohigh, bytes-hasnohigh);
explicit_bzero(buf, bytes);
free(buf);
return (0);
}
void
buffer_put_bignum2(Buffer *buffer, const BIGNUM *value)
{
if (buffer_put_bignum2_ret(buffer, value) == -1)
fatal("buffer_put_bignum2: buffer error");
}
int
buffer_get_bignum2_ret(Buffer *buffer, BIGNUM *value)
{
u_int len;
u_char *bin;
if ((bin = buffer_get_string_ret(buffer, &len)) == NULL) {
error("buffer_get_bignum2_ret: invalid bignum");
return (-1);
}
if (len > 0 && (bin[0] & 0x80)) {
error("buffer_get_bignum2_ret: negative numbers not supported");
free(bin);
return (-1);
}
if (len > 8 * 1024) {
error("buffer_get_bignum2_ret: cannot handle BN of size %d",
len);
free(bin);
return (-1);
}
if (BN_bin2bn(bin, len, value) == NULL) {
error("buffer_get_bignum2_ret: BN_bin2bn failed");
free(bin);
return (-1);
}
free(bin);
return (0);
}
void
buffer_get_bignum2(Buffer *buffer, BIGNUM *value)
{
if (buffer_get_bignum2_ret(buffer, value) == -1)
fatal("buffer_get_bignum2: buffer error");
}
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