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/*
* gzip.c - hooks for compression of packets
*
* This file is part of the SSH Library
*
* Copyright (c) 2003 by Aris Adamantiadis
* Copyright (c) 2009 by Andreas Schneider <mail@cynapses.org>
*
* The SSH Library is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2.1 of the License, or (at your
* option) any later version.
*
* The SSH Library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
* License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with the SSH Library; see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
* MA 02111-1307, USA.
*/
#include "config.h"
#include <string.h>
#include <stdlib.h>
#include <zlib.h>
#include "libssh/priv.h"
#include "libssh/buffer.h"
#include "libssh/crypto.h"
#include "libssh/session.h"
#define BLOCKSIZE 4092
static z_stream *initcompress(ssh_session session, int level) {
z_stream *stream = NULL;
int status;
stream = malloc(sizeof(z_stream));
if (stream == NULL) {
return NULL;
}
memset(stream, 0, sizeof(z_stream));
status = deflateInit(stream, level);
if (status != Z_OK) {
SAFE_FREE(stream);
ssh_set_error(session, SSH_FATAL,
"status %d inititalising zlib deflate", status);
return NULL;
}
return stream;
}
static ssh_buffer gzip_compress(ssh_session session,ssh_buffer source,int level){
z_stream *zout = session->current_crypto->compress_out_ctx;
void *in_ptr = buffer_get_rest(source);
unsigned long in_size = buffer_get_rest_len(source);
ssh_buffer dest = NULL;
unsigned char out_buf[BLOCKSIZE] = {0};
unsigned long len;
int status;
if(zout == NULL) {
zout = session->current_crypto->compress_out_ctx = initcompress(session, level);
if (zout == NULL) {
return NULL;
}
}
dest = ssh_buffer_new();
if (dest == NULL) {
return NULL;
}
zout->next_out = out_buf;
zout->next_in = in_ptr;
zout->avail_in = in_size;
do {
zout->avail_out = BLOCKSIZE;
status = deflate(zout, Z_PARTIAL_FLUSH);
if (status != Z_OK) {
ssh_buffer_free(dest);
ssh_set_error(session, SSH_FATAL,
"status %d deflating zlib packet", status);
return NULL;
}
len = BLOCKSIZE - zout->avail_out;
if (buffer_add_data(dest, out_buf, len) < 0) {
ssh_buffer_free(dest);
return NULL;
}
zout->next_out = out_buf;
} while (zout->avail_out == 0);
return dest;
}
int compress_buffer(ssh_session session, ssh_buffer buf) {
ssh_buffer dest = NULL;
dest = gzip_compress(session, buf, session->opts.compressionlevel);
if (dest == NULL) {
return -1;
}
if (buffer_reinit(buf) < 0) {
ssh_buffer_free(dest);
return -1;
}
if (buffer_add_data(buf, buffer_get_rest(dest), buffer_get_rest_len(dest)) < 0) {
ssh_buffer_free(dest);
return -1;
}
ssh_buffer_free(dest);
return 0;
}
/* decompression */
static z_stream *initdecompress(ssh_session session) {
z_stream *stream = NULL;
int status;
stream = malloc(sizeof(z_stream));
if (stream == NULL) {
return NULL;
}
memset(stream,0,sizeof(z_stream));
status = inflateInit(stream);
if (status != Z_OK) {
SAFE_FREE(stream);
ssh_set_error(session, SSH_FATAL,
"Status = %d initiating inflate context!", status);
return NULL;
}
return stream;
}
static ssh_buffer gzip_decompress(ssh_session session, ssh_buffer source, size_t maxlen) {
z_stream *zin = session->current_crypto->compress_in_ctx;
void *in_ptr = buffer_get_rest(source);
unsigned long in_size = buffer_get_rest_len(source);
unsigned char out_buf[BLOCKSIZE] = {0};
ssh_buffer dest = NULL;
unsigned long len;
int status;
if (zin == NULL) {
zin = session->current_crypto->compress_in_ctx = initdecompress(session);
if (zin == NULL) {
return NULL;
}
}
dest = ssh_buffer_new();
if (dest == NULL) {
return NULL;
}
zin->next_out = out_buf;
zin->next_in = in_ptr;
zin->avail_in = in_size;
do {
zin->avail_out = BLOCKSIZE;
status = inflate(zin, Z_PARTIAL_FLUSH);
if (status != Z_OK && status != Z_BUF_ERROR) {
ssh_set_error(session, SSH_FATAL,
"status %d inflating zlib packet", status);
ssh_buffer_free(dest);
return NULL;
}
len = BLOCKSIZE - zin->avail_out;
if (buffer_add_data(dest,out_buf,len) < 0) {
ssh_buffer_free(dest);
return NULL;
}
if (buffer_get_rest_len(dest) > maxlen){
/* Size of packet exceeded, avoid a denial of service attack */
ssh_buffer_free(dest);
return NULL;
}
zin->next_out = out_buf;
} while (zin->avail_out == 0);
return dest;
}
int decompress_buffer(ssh_session session,ssh_buffer buf, size_t maxlen){
ssh_buffer dest = NULL;
dest = gzip_decompress(session,buf, maxlen);
if (dest == NULL) {
return -1;
}
if (buffer_reinit(buf) < 0) {
ssh_buffer_free(dest);
return -1;
}
if (buffer_add_data(buf, buffer_get_rest(dest), buffer_get_rest_len(dest)) < 0) {
ssh_buffer_free(dest);
return -1;
}
ssh_buffer_free(dest);
return 0;
}
/* vim: set ts=2 sw=2 et cindent: */
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