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/* $OpenBSD: bufaux.c,v 1.57 2014/04/16 23:22:45 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"
/*
* Returns integers from the buffer (msb first).
*/
int
buffer_get_short_ret(u_short *ret, Buffer *buffer)
{
u_char buf[2];
if (buffer_get_ret(buffer, (char *) buf, 2) == -1)
return (-1);
*ret = get_u16(buf);
return (0);
}
u_short
buffer_get_short(Buffer *buffer)
{
u_short ret;
if (buffer_get_short_ret(&ret, buffer) == -1)
fatal("buffer_get_short: buffer error");
return (ret);
}
int
buffer_get_int_ret(u_int *ret, Buffer *buffer)
{
u_char buf[4];
if (buffer_get_ret(buffer, (char *) buf, 4) == -1)
return (-1);
if (ret != NULL)
*ret = get_u32(buf);
return (0);
}
u_int
buffer_get_int(Buffer *buffer)
{
u_int ret;
if (buffer_get_int_ret(&ret, buffer) == -1)
fatal("buffer_get_int: buffer error");
return (ret);
}
int
buffer_get_int64_ret(u_int64_t *ret, Buffer *buffer)
{
u_char buf[8];
if (buffer_get_ret(buffer, (char *) buf, 8) == -1)
return (-1);
if (ret != NULL)
*ret = get_u64(buf);
return (0);
}
u_int64_t
buffer_get_int64(Buffer *buffer)
{
u_int64_t ret;
if (buffer_get_int64_ret(&ret, buffer) == -1)
fatal("buffer_get_int: buffer error");
return (ret);
}
/*
* Stores integers in the buffer, msb first.
*/
void
buffer_put_short(Buffer *buffer, u_short value)
{
char buf[2];
put_u16(buf, value);
buffer_append(buffer, buf, 2);
}
void
buffer_put_int(Buffer *buffer, u_int value)
{
char buf[4];
put_u32(buf, value);
buffer_append(buffer, buf, 4);
}
void
buffer_put_int64(Buffer *buffer, u_int64_t value)
{
char buf[8];
put_u64(buf, value);
buffer_append(buffer, buf, 8);
}
/*
* Returns an arbitrary binary string from the buffer. The string cannot
* be longer than 256k. The returned value points to memory allocated
* with xmalloc; it is the responsibility of the calling function to free
* the data. If length_ptr is non-NULL, the length of the returned data
* will be stored there. A null character will be automatically appended
* to the returned string, and is not counted in length.
*/
void *
buffer_get_string_ret(Buffer *buffer, u_int *length_ptr)
{
u_char *value;
u_int len;
/* Get the length. */
if (buffer_get_int_ret(&len, buffer) != 0) {
error("buffer_get_string_ret: cannot extract length");
return (NULL);
}
if (len > 256 * 1024) {
error("buffer_get_string_ret: bad string length %u", len);
return (NULL);
}
/* Allocate space for the string. Add one byte for a null character. */
value = xmalloc(len + 1);
/* Get the string. */
if (buffer_get_ret(buffer, value, len) == -1) {
error("buffer_get_string_ret: buffer_get failed");
free(value);
return (NULL);
}
/* Append a null character to make processing easier. */
value[len] = '\0';
/* Optionally return the length of the string. */
if (length_ptr)
*length_ptr = len;
return (value);
}
void *
buffer_get_string(Buffer *buffer, u_int *length_ptr)
{
void *ret;
if ((ret = buffer_get_string_ret(buffer, length_ptr)) == NULL)
fatal("buffer_get_string: buffer error");
return (ret);
}
char *
buffer_get_cstring_ret(Buffer *buffer, u_int *length_ptr)
{
u_int length;
char *cp, *ret = buffer_get_string_ret(buffer, &length);
if (ret == NULL)
return NULL;
if ((cp = memchr(ret, '\0', length)) != NULL) {
/* XXX allow \0 at end-of-string for a while, remove later */
if (cp == ret + length - 1)
error("buffer_get_cstring_ret: string contains \\0");
else {
explicit_bzero(ret, length);
free(ret);
return NULL;
}
}
if (length_ptr != NULL)
*length_ptr = length;
return ret;
}
char *
buffer_get_cstring(Buffer *buffer, u_int *length_ptr)
{
char *ret;
if ((ret = buffer_get_cstring_ret(buffer, length_ptr)) == NULL)
fatal("buffer_get_cstring: buffer error");
return ret;
}
void *
buffer_get_string_ptr_ret(Buffer *buffer, u_int *length_ptr)
{
void *ptr;
u_int len;
if (buffer_get_int_ret(&len, buffer) != 0)
return NULL;
if (len > 256 * 1024) {
error("buffer_get_string_ptr: bad string length %u", len);
return NULL;
}
ptr = buffer_ptr(buffer);
buffer_consume(buffer, len);
if (length_ptr)
*length_ptr = len;
return (ptr);
}
void *
buffer_get_string_ptr(Buffer *buffer, u_int *length_ptr)
{
void *ret;
if ((ret = buffer_get_string_ptr_ret(buffer, length_ptr)) == NULL)
fatal("buffer_get_string_ptr: buffer error");
return (ret);
}
/*
* Stores and arbitrary binary string in the buffer.
*/
void
buffer_put_string(Buffer *buffer, const void *buf, u_int len)
{
buffer_put_int(buffer, len);
buffer_append(buffer, buf, len);
}
void
buffer_put_cstring(Buffer *buffer, const char *s)
{
if (s == NULL)
fatal("buffer_put_cstring: s == NULL");
buffer_put_string(buffer, s, strlen(s));
}
/*
* Returns a character from the buffer (0 - 255).
*/
int
buffer_get_char_ret(u_char *ret, Buffer *buffer)
{
if (buffer_get_ret(buffer, ret, 1) == -1) {
error("buffer_get_char_ret: buffer_get_ret failed");
return (-1);
}
return (0);
}
int
buffer_get_char(Buffer *buffer)
{
u_char ch;
if (buffer_get_char_ret(&ch, buffer) == -1)
fatal("buffer_get_char: buffer error");
return ch;
}
/*
* Stores a character in the buffer.
*/
void
buffer_put_char(Buffer *buffer, int value)
{
char ch = value;
buffer_append(buffer, &ch, 1);
}
/* Pseudo bignum functions */
void *
buffer_get_bignum2_as_string_ret(Buffer *buffer, u_int *length_ptr)
{
u_int len;
u_char *bin, *p, *ret;
if ((p = bin = buffer_get_string_ret(buffer, &len)) == NULL) {
error("%s: invalid bignum", __func__);
return NULL;
}
if (len > 0 && (bin[0] & 0x80)) {
error("%s: negative numbers not supported", __func__);
free(bin);
return NULL;
}
if (len > 8 * 1024) {
error("%s: cannot handle BN of size %d", __func__, len);
free(bin);
return NULL;
}
/* Skip zero prefix on numbers with the MSB set */
if (len > 1 && bin[0] == 0x00 && (bin[1] & 0x80) != 0) {
p++;
len--;
}
ret = xmalloc(len);
memcpy(ret, p, len);
explicit_bzero(p, len);
free(bin);
return ret;
}
void *
buffer_get_bignum2_as_string(Buffer *buffer, u_int *l)
{
void *ret = buffer_get_bignum2_as_string_ret(buffer, l);
if (ret == NULL)
fatal("%s: buffer error", __func__);
return ret;
}
/*
* Stores a string using the bignum encoding rules (\0 pad if MSB set).
*/
void
buffer_put_bignum2_from_string(Buffer *buffer, const u_char *s, u_int l)
{
u_char *buf, *p;
int pad = 0;
if (l > 8 * 1024)
fatal("%s: length %u too long", __func__, l);
/* Skip leading zero bytes */
for (; l > 0 && *s == 0; l--, s++)
;
p = buf = xmalloc(l + 1);
/*
* If most significant bit is set then prepend a zero byte to
* avoid interpretation as a negative number.
*/
if (l > 0 && (s[0] & 0x80) != 0) {
*p++ = '\0';
pad = 1;
}
memcpy(p, s, l);
buffer_put_string(buffer, buf, l + pad);
explicit_bzero(buf, l + pad);
free(buf);
}
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