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/*
*
* bufaux.c
*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
*
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
* All rights reserved
*
* Created: Wed Mar 29 02:24:47 1995 ylo
*
* Auxiliary functions for storing and retrieving various data types to/from
* Buffers.
*
* SSH2 packet format added by Markus Friedl
*
*/
#include "includes.h"
RCSID("$Id: bufaux.c,v 1.12 2000/04/16 02:31:50 damien Exp $");
#include "ssh.h"
#include <openssl/bn.h>
#include "bufaux.h"
#include "xmalloc.h"
#include "getput.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.
*/
void
buffer_put_bignum(Buffer *buffer, BIGNUM *value)
{
int bits = BN_num_bits(value);
int bin_size = (bits + 7) / 8;
char unsigned *buf = xmalloc(bin_size);
int oi;
char msg[2];
/* Get the value of in binary */
oi = BN_bn2bin(value, buf);
if (oi != bin_size)
fatal("buffer_put_bignum: BN_bn2bin() failed: oi %d != bin_size %d",
oi, bin_size);
/* Store the number of bits in the buffer in two bytes, msb first. */
PUT_16BIT(msg, bits);
buffer_append(buffer, msg, 2);
/* Store the binary data. */
buffer_append(buffer, (char *)buf, oi);
memset(buf, 0, bin_size);
xfree(buf);
}
/*
* Retrieves an BIGNUM from the buffer.
*/
int
buffer_get_bignum(Buffer *buffer, BIGNUM *value)
{
int bits, bytes;
unsigned char buf[2], *bin;
/* Get the number for bits. */
buffer_get(buffer, (char *) buf, 2);
bits = GET_16BIT(buf);
/* Compute the number of binary bytes that follow. */
bytes = (bits + 7) / 8;
if (buffer_len(buffer) < bytes)
fatal("buffer_get_bignum: input buffer too small");
bin = (unsigned char*) buffer_ptr(buffer);
BN_bin2bn(bin, bytes, value);
buffer_consume(buffer, bytes);
return 2 + bytes;
}
/*
* Stores an BIGNUM in the buffer in SSH2 format.
*/
void
buffer_put_bignum2(Buffer *buffer, BIGNUM *value)
{
int bytes = BN_num_bytes(value) + 1;
unsigned char *buf = xmalloc(bytes);
int oi;
int hasnohigh = 0;
buf[0] = '\0';
/* Get the value of in binary */
oi = BN_bn2bin(value, buf+1);
if (oi != bytes-1)
fatal("buffer_put_bignum: BN_bn2bin() failed: oi %d != bin_size %d",
oi, bytes);
hasnohigh = (buf[1] & 0x80) ? 0 : 1;
if (value->neg) {
/**XXX should be two's-complement */
int i, carry;
unsigned char *uc = buf;
log("negativ!");
for(i = bytes-1, carry = 1; i>=0; i--) {
uc[i] ^= 0xff;
if(carry)
carry = !++uc[i];
}
}
buffer_put_string(buffer, buf+hasnohigh, bytes-hasnohigh);
memset(buf, 0, bytes);
xfree(buf);
}
int
buffer_get_bignum2(Buffer *buffer, BIGNUM *value)
{
/**XXX should be two's-complement */
int len;
unsigned char *bin = (unsigned char *)buffer_get_string(buffer, (unsigned int *)&len);
BN_bin2bn(bin, len, value);
xfree(bin);
return len;
}
/*
* Returns an integer from the buffer (4 bytes, msb first).
*/
unsigned int
buffer_get_int(Buffer *buffer)
{
unsigned char buf[4];
buffer_get(buffer, (char *) buf, 4);
return GET_32BIT(buf);
}
/*
* Stores an integer in the buffer in 4 bytes, msb first.
*/
void
buffer_put_int(Buffer *buffer, unsigned int value)
{
char buf[4];
PUT_32BIT(buf, value);
buffer_append(buffer, buf, 4);
}
/*
* 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.
*/
char *
buffer_get_string(Buffer *buffer, unsigned int *length_ptr)
{
unsigned int len;
char *value;
/* Get the length. */
len = buffer_get_int(buffer);
if (len > 256 * 1024)
fatal("Received packet with bad string length %d", len);
/* Allocate space for the string. Add one byte for a null character. */
value = xmalloc(len + 1);
/* Get the string. */
buffer_get(buffer, value, len);
/* 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;
}
/*
* Stores and arbitrary binary string in the buffer.
*/
void
buffer_put_string(Buffer *buffer, const void *buf, unsigned int len)
{
buffer_put_int(buffer, len);
buffer_append(buffer, buf, len);
}
void
buffer_put_cstring(Buffer *buffer, const char *s)
{
buffer_put_string(buffer, s, strlen(s));
}
/*
* Returns a character from the buffer (0 - 255).
*/
int
buffer_get_char(Buffer *buffer)
{
char ch;
buffer_get(buffer, &ch, 1);
return (unsigned char) ch;
}
/*
* Stores a character in the buffer.
*/
void
buffer_put_char(Buffer *buffer, int value)
{
char ch = value;
buffer_append(buffer, &ch, 1);
}
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