231 lines
6.3 KiB
C
231 lines
6.3 KiB
C
/*
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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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RCSID("$OpenBSD: bufaux.c,v 1.13 2000/09/07 20:27:50 deraadt Exp $");
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RCSID("$FreeBSD$");
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#include "ssh.h"
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#include <openssl/bn.h>
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#include "bufaux.h"
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#include "xmalloc.h"
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#include "getput.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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void
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buffer_put_bignum(Buffer *buffer, 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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char unsigned *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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fatal("buffer_put_bignum: BN_bn2bin() failed: oi %d != bin_size %d",
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oi, bin_size);
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/* Store the number of bits in the buffer in two bytes, msb first. */
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PUT_16BIT(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, (char *)buf, oi);
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memset(buf, 0, bin_size);
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xfree(buf);
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}
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/*
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* Retrieves an BIGNUM from the buffer.
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*/
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int
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buffer_get_bignum(Buffer *buffer, BIGNUM *value)
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{
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int bits, bytes;
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unsigned char buf[2], *bin;
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/* Get the number for bits. */
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buffer_get(buffer, (char *) buf, 2);
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bits = GET_16BIT(buf);
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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 (buffer_len(buffer) < bytes)
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fatal("buffer_get_bignum: input buffer too small");
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bin = (unsigned char*) buffer_ptr(buffer);
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BN_bin2bn(bin, bytes, value);
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buffer_consume(buffer, bytes);
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return 2 + bytes;
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}
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/*
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* Stores an BIGNUM in the buffer in SSH2 format.
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*/
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void
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buffer_put_bignum2(Buffer *buffer, BIGNUM *value)
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{
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int bytes = BN_num_bytes(value) + 1;
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unsigned char *buf = xmalloc(bytes);
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int oi;
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int hasnohigh = 0;
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buf[0] = '\0';
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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 != bytes-1)
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fatal("buffer_put_bignum: BN_bn2bin() failed: oi %d != bin_size %d",
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oi, bytes);
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hasnohigh = (buf[1] & 0x80) ? 0 : 1;
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if (value->neg) {
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/**XXX should be two's-complement */
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int i, carry;
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unsigned char *uc = buf;
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log("negativ!");
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for(i = bytes-1, carry = 1; i>=0; i--) {
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uc[i] ^= 0xff;
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if(carry)
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carry = !++uc[i];
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}
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}
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buffer_put_string(buffer, buf+hasnohigh, bytes-hasnohigh);
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memset(buf, 0, bytes);
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xfree(buf);
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}
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int
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buffer_get_bignum2(Buffer *buffer, BIGNUM *value)
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{
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/**XXX should be two's-complement */
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int len;
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unsigned char *bin = (unsigned char *)buffer_get_string(buffer, (unsigned int *)&len);
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BN_bin2bn(bin, len, value);
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xfree(bin);
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return len;
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}
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/*
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* Returns an integer from the buffer (4 bytes, msb first).
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*/
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unsigned int
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buffer_get_int(Buffer *buffer)
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{
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unsigned char buf[4];
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buffer_get(buffer, (char *) buf, 4);
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return GET_32BIT(buf);
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}
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/*
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* Stores an integer in the buffer in 4 bytes, msb first.
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*/
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void
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buffer_put_int(Buffer *buffer, unsigned int value)
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{
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char buf[4];
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PUT_32BIT(buf, value);
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buffer_append(buffer, buf, 4);
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}
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/*
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* Returns an arbitrary binary string from the buffer. The string cannot
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* be longer than 256k. The returned value points to memory allocated
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* with xmalloc; it is the responsibility of the calling function to free
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* the data. If length_ptr is non-NULL, the length of the returned data
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* will be stored there. A null character will be automatically appended
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* to the returned string, and is not counted in length.
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*/
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char *
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buffer_get_string(Buffer *buffer, unsigned int *length_ptr)
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{
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unsigned int len;
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char *value;
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/* Get the length. */
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len = buffer_get_int(buffer);
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if (len > 256 * 1024)
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fatal("Received packet with bad string length %d", len);
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/* Allocate space for the string. Add one byte for a null character. */
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value = xmalloc(len + 1);
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/* Get the string. */
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buffer_get(buffer, value, len);
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/* Append a null character to make processing easier. */
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value[len] = 0;
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/* Optionally return the length of the string. */
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if (length_ptr)
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*length_ptr = len;
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return value;
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}
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/*
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* Stores and arbitrary binary string in the buffer.
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*/
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void
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buffer_put_string(Buffer *buffer, const void *buf, unsigned int len)
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{
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buffer_put_int(buffer, len);
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buffer_append(buffer, buf, len);
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}
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void
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buffer_put_cstring(Buffer *buffer, const char *s)
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{
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buffer_put_string(buffer, s, strlen(s));
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}
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/*
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* Returns a character from the buffer (0 - 255).
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*/
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int
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buffer_get_char(Buffer *buffer)
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{
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char ch;
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buffer_get(buffer, &ch, 1);
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return (unsigned char) ch;
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}
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/*
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* Stores a character in the buffer.
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*/
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void
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buffer_put_char(Buffer *buffer, int value)
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{
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char ch = value;
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buffer_append(buffer, &ch, 1);
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}
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