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Diffstat (limited to 'compress.c')
| -rw-r--r-- | compress.c | 160 |
1 files changed, 160 insertions, 0 deletions
diff --git a/compress.c b/compress.c new file mode 100644 index 00000000..c3267f73 --- /dev/null +++ b/compress.c @@ -0,0 +1,160 @@ +/* + +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 1999/10/27 03:42:44 damien 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); + } + } +} + |