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/*
compress.c
Author: Tatu Ylonen <ylo@cs.hut.fi>
Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
All rights reserved
Created: Wed Oct 25 22:12:46 1995 ylo
Interface to packet compression for ssh.
*/
#include "includes.h"
RCSID("$Id: compress.c,v 1.1 1999/09/26 20:53:34 deraadt Exp $");
#include "ssh.h"
#include "buffer.h"
#include "zlib.h"
static z_stream incoming_stream;
static z_stream outgoing_stream;
/* Initializes compression; level is compression level from 1 to 9 (as in
gzip). */
void buffer_compress_init(int level)
{
debug("Enabling compression at level %d.", level);
if (level < 1 || level > 9)
fatal("Bad compression level %d.", level);
inflateInit(&incoming_stream);
deflateInit(&outgoing_stream, level);
}
/* Frees any data structures allocated for compression. */
void buffer_compress_uninit()
{
debug("compress outgoing: raw data %lu, compressed %lu, factor %.2f",
outgoing_stream.total_in, outgoing_stream.total_out,
outgoing_stream.total_in == 0 ? 0.0 :
(double)outgoing_stream.total_out / outgoing_stream.total_in);
debug("compress incoming: raw data %lu, compressed %lu, factor %.2f",
incoming_stream.total_out, incoming_stream.total_in,
incoming_stream.total_out == 0 ? 0.0 :
(double)incoming_stream.total_in / incoming_stream.total_out);
inflateEnd(&incoming_stream);
deflateEnd(&outgoing_stream);
}
/* Compresses the contents of input_buffer into output_buffer. All
packets compressed using this function will form a single
compressed data stream; however, data will be flushed at the end of
every call so that each output_buffer can be decompressed
independently (but in the appropriate order since they together
form a single compression stream) by the receiver. This appends
the compressed data to the output buffer. */
void buffer_compress(Buffer *input_buffer, Buffer *output_buffer)
{
char buf[4096];
int status;
/* This case is not handled below. */
if (buffer_len(input_buffer) == 0)
return;
/* Input is the contents of the input buffer. */
outgoing_stream.next_in = buffer_ptr(input_buffer);
outgoing_stream.avail_in = buffer_len(input_buffer);
/* Loop compressing until deflate() returns with avail_out != 0. */
do
{
/* Set up fixed-size output buffer. */
outgoing_stream.next_out = buf;
outgoing_stream.avail_out = sizeof(buf);
/* Compress as much data into the buffer as possible. */
status = deflate(&outgoing_stream, Z_PARTIAL_FLUSH);
switch (status)
{
case Z_OK:
/* Append compressed data to output_buffer. */
buffer_append(output_buffer, buf,
sizeof(buf) - outgoing_stream.avail_out);
break;
case Z_STREAM_END:
fatal("buffer_compress: deflate returned Z_STREAM_END");
/*NOTREACHED*/
case Z_STREAM_ERROR:
fatal("buffer_compress: deflate returned Z_STREAM_ERROR");
/*NOTREACHED*/
case Z_BUF_ERROR:
fatal("buffer_compress: deflate returned Z_BUF_ERROR");
/*NOTREACHED*/
default:
fatal("buffer_compress: deflate returned %d", status);
/*NOTREACHED*/
}
}
while (outgoing_stream.avail_out == 0);
}
/* Uncompresses the contents of input_buffer into output_buffer. All
packets uncompressed using this function will form a single
compressed data stream; however, data will be flushed at the end of
every call so that each output_buffer. This must be called for the
same size units that the buffer_compress was called, and in the
same order that buffers compressed with that. This appends the
uncompressed data to the output buffer. */
void buffer_uncompress(Buffer *input_buffer, Buffer *output_buffer)
{
char buf[4096];
int status;
incoming_stream.next_in = buffer_ptr(input_buffer);
incoming_stream.avail_in = buffer_len(input_buffer);
incoming_stream.next_out = buf;
incoming_stream.avail_out = sizeof(buf);
for (;;)
{
status = inflate(&incoming_stream, Z_PARTIAL_FLUSH);
switch (status)
{
case Z_OK:
buffer_append(output_buffer, buf,
sizeof(buf) - incoming_stream.avail_out);
incoming_stream.next_out = buf;
incoming_stream.avail_out = sizeof(buf);
break;
case Z_STREAM_END:
fatal("buffer_uncompress: inflate returned Z_STREAM_END");
/*NOTREACHED*/
case Z_DATA_ERROR:
fatal("buffer_uncompress: inflate returned Z_DATA_ERROR");
/*NOTREACHED*/
case Z_STREAM_ERROR:
fatal("buffer_uncompress: inflate returned Z_STREAM_ERROR");
/*NOTREACHED*/
case Z_BUF_ERROR:
/* Comments in zlib.h say that we should keep calling inflate()
until we get an error. This appears to be the error that we
get. */
return;
case Z_MEM_ERROR:
fatal("buffer_uncompress: inflate returned Z_MEM_ERROR");
/*NOTREACHED*/
default:
fatal("buffer_uncompress: inflate returned %d", status);
}
}
}
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