144 lines
4.1 KiB
C
144 lines
4.1 KiB
C
/*
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*
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* compress.c
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*
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* Author: Tatu Ylonen <ylo@cs.hut.fi>
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*
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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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*
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* Created: Wed Oct 25 22:12:46 1995 ylo
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*
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* Interface to packet compression for ssh.
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*
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*/
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#include "includes.h"
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RCSID("$Id: compress.c,v 1.7 2000/04/14 10:30:31 markus Exp $");
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#include "ssh.h"
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#include "buffer.h"
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#include "zlib.h"
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static z_stream incoming_stream;
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static z_stream outgoing_stream;
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/*
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* Initializes compression; level is compression level from 1 to 9
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* (as in gzip).
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*/
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void
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buffer_compress_init(int level)
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{
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debug("Enabling compression at level %d.", level);
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if (level < 1 || level > 9)
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fatal("Bad compression level %d.", level);
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inflateInit(&incoming_stream);
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deflateInit(&outgoing_stream, level);
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}
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/* Frees any data structures allocated for compression. */
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void
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buffer_compress_uninit()
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{
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debug("compress outgoing: raw data %lu, compressed %lu, factor %.2f",
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outgoing_stream.total_in, outgoing_stream.total_out,
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outgoing_stream.total_in == 0 ? 0.0 :
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(double) outgoing_stream.total_out / outgoing_stream.total_in);
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debug("compress incoming: raw data %lu, compressed %lu, factor %.2f",
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incoming_stream.total_out, incoming_stream.total_in,
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incoming_stream.total_out == 0 ? 0.0 :
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(double) incoming_stream.total_in / incoming_stream.total_out);
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inflateEnd(&incoming_stream);
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deflateEnd(&outgoing_stream);
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}
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/*
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* Compresses the contents of input_buffer into output_buffer. All packets
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* compressed using this function will form a single compressed data stream;
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* however, data will be flushed at the end of every call so that each
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* output_buffer can be decompressed independently (but in the appropriate
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* order since they together form a single compression stream) by the
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* receiver. This appends the compressed data to the output buffer.
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*/
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void
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buffer_compress(Buffer * input_buffer, Buffer * output_buffer)
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{
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char buf[4096];
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int status;
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/* This case is not handled below. */
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if (buffer_len(input_buffer) == 0)
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return;
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/* Input is the contents of the input buffer. */
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outgoing_stream.next_in = (unsigned char *) buffer_ptr(input_buffer);
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outgoing_stream.avail_in = buffer_len(input_buffer);
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/* Loop compressing until deflate() returns with avail_out != 0. */
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do {
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/* Set up fixed-size output buffer. */
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outgoing_stream.next_out = (unsigned char *)buf;
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outgoing_stream.avail_out = sizeof(buf);
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/* Compress as much data into the buffer as possible. */
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status = deflate(&outgoing_stream, Z_PARTIAL_FLUSH);
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switch (status) {
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case Z_OK:
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/* Append compressed data to output_buffer. */
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buffer_append(output_buffer, buf,
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sizeof(buf) - outgoing_stream.avail_out);
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break;
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default:
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fatal("buffer_compress: deflate returned %d", status);
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/* NOTREACHED */
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}
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} while (outgoing_stream.avail_out == 0);
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}
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/*
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* Uncompresses the contents of input_buffer into output_buffer. All packets
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* uncompressed using this function will form a single compressed data
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* stream; however, data will be flushed at the end of every call so that
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* each output_buffer. This must be called for the same size units that the
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* buffer_compress was called, and in the same order that buffers compressed
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* with that. This appends the uncompressed data to the output buffer.
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*/
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void
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buffer_uncompress(Buffer * input_buffer, Buffer * output_buffer)
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{
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char buf[4096];
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int status;
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incoming_stream.next_in = (unsigned char *) buffer_ptr(input_buffer);
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incoming_stream.avail_in = buffer_len(input_buffer);
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for (;;) {
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/* Set up fixed-size output buffer. */
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incoming_stream.next_out = (unsigned char *) buf;
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incoming_stream.avail_out = sizeof(buf);
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status = inflate(&incoming_stream, Z_PARTIAL_FLUSH);
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switch (status) {
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case Z_OK:
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buffer_append(output_buffer, buf,
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sizeof(buf) - incoming_stream.avail_out);
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break;
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case Z_BUF_ERROR:
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/*
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* Comments in zlib.h say that we should keep calling
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* inflate() until we get an error. This appears to
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* be the error that we get.
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*/
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return;
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default:
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fatal("buffer_uncompress: inflate returned %d", status);
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/* NOTREACHED */
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}
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}
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}
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