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