crypto/openssh/compress.c

   1 /*
   2  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   3  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   4  *                    All rights reserved
   5  * Interface to packet compression for ssh.
   6  *
   7  * As far as I am concerned, the code I have written for this software
   8  * can be used freely for any purpose.  Any derived versions of this
   9  * software must be clearly marked as such, and if the derived work is
  10  * incompatible with the protocol description in the RFC file, it must be
  11  * called by a name other than "ssh" or "Secure Shell".
  12  */
  13
  14 #include "includes.h"
  15 RCSID("$OpenBSD: compress.c,v 1.19 2002/03/18 17:31:54 provos Exp $");
  16
  17 #include "log.h"
  18 #include "buffer.h"
  19 #include "zlib.h"
  20 #include "compress.h"
  21
  22 z_stream incoming_stream;
  23 z_stream outgoing_stream;
  24 static int compress_init_send_called = 0;
  25 static int compress_init_recv_called = 0;
  26 static int inflate_failed = 0;
  27 static int deflate_failed = 0;
  28
  29 /*
  30  * Initializes compression; level is compression level from 1 to 9
  31  * (as in gzip).
  32  */
  33
  34 void
  35 buffer_compress_init_send(int level)
  36 {
  37         if (compress_init_send_called == 1)
  38                 deflateEnd(&outgoing_stream);
  39         compress_init_send_called = 1;
  40         debug("Enabling compression at level %d.", level);
  41         if (level < 1 || level > 9)
  42                 fatal("Bad compression level %d.", level);
  43         deflateInit(&outgoing_stream, level);
  44 }
  45 void
  46 buffer_compress_init_recv(void)
  47 {
  48         if (compress_init_recv_called == 1)
  49                 inflateEnd(&incoming_stream);
  50         compress_init_recv_called = 1;
  51         inflateInit(&incoming_stream);
  52 }
  53
  54 /* Frees any data structures allocated for compression. */
  55
  56 void
  57 buffer_compress_uninit(void)
  58 {
  59         debug("compress outgoing: raw data %lu, compressed %lu, factor %.2f",
  60             outgoing_stream.total_in, outgoing_stream.total_out,
  61             outgoing_stream.total_in == 0 ? 0.0 :
  62             (double) outgoing_stream.total_out / outgoing_stream.total_in);
  63         debug("compress incoming: raw data %lu, compressed %lu, factor %.2f",
  64             incoming_stream.total_out, incoming_stream.total_in,
  65             incoming_stream.total_out == 0 ? 0.0 :
  66             (double) incoming_stream.total_in / incoming_stream.total_out);
  67         if (compress_init_recv_called == 1 && inflate_failed == 0)
  68                 inflateEnd(&incoming_stream);
  69         if (compress_init_send_called == 1 && deflate_failed == 0)
  70                 deflateEnd(&outgoing_stream);
  71 }
  72
  73 /*
  74  * Compresses the contents of input_buffer into output_buffer.  All packets
  75  * compressed using this function will form a single compressed data stream;
  76  * however, data will be flushed at the end of every call so that each
  77  * output_buffer can be decompressed independently (but in the appropriate
  78  * order since they together form a single compression stream) by the
  79  * receiver.  This appends the compressed data to the output buffer.
  80  */
  81
  82 void
  83 buffer_compress(Buffer * input_buffer, Buffer * output_buffer)
  84 {
  85         u_char buf[4096];
  86         int status;
  87
  88         /* This case is not handled below. */
  89         if (buffer_len(input_buffer) == 0)
  90                 return;
  91
  92         /* Input is the contents of the input buffer. */
  93         outgoing_stream.next_in = buffer_ptr(input_buffer);
  94         outgoing_stream.avail_in = buffer_len(input_buffer);
  95
  96         /* Loop compressing until deflate() returns with avail_out != 0. */
  97         do {
  98                 /* Set up fixed-size output buffer. */
  99                 outgoing_stream.next_out = buf;
 100                 outgoing_stream.avail_out = sizeof(buf);
 101
 102                 /* Compress as much data into the buffer as possible. */
 103                 status = deflate(&outgoing_stream, Z_PARTIAL_FLUSH);
 104                 switch (status) {
 105                 case Z_OK:
 106                         /* Append compressed data to output_buffer. */
 107                         buffer_append(output_buffer, buf,
 108                             sizeof(buf) - outgoing_stream.avail_out);
 109                         break;
 110                 default:
 111                         deflate_failed = 1;
 112                         fatal("buffer_compress: deflate returned %d", status);
 113                         /* NOTREACHED */
 114                 }
 115         } while (outgoing_stream.avail_out == 0);
 116 }
 117
 118 /*
 119  * Uncompresses the contents of input_buffer into output_buffer.  All packets
 120  * uncompressed using this function will form a single compressed data
 121  * stream; however, data will be flushed at the end of every call so that
 122  * each output_buffer.  This must be called for the same size units that the
 123  * buffer_compress was called, and in the same order that buffers compressed
 124  * with that.  This appends the uncompressed data to the output buffer.
 125  */
 126
 127 void
 128 buffer_uncompress(Buffer * input_buffer, Buffer * output_buffer)
 129 {
 130         u_char buf[4096];
 131         int status;
 132
 133         incoming_stream.next_in = buffer_ptr(input_buffer);
 134         incoming_stream.avail_in = buffer_len(input_buffer);
 135
 136         for (;;) {
 137                 /* Set up fixed-size output buffer. */
 138                 incoming_stream.next_out = buf;
 139                 incoming_stream.avail_out = sizeof(buf);
 140
 141                 status = inflate(&incoming_stream, Z_PARTIAL_FLUSH);
 142                 switch (status) {
 143                 case Z_OK:
 144                         buffer_append(output_buffer, buf,
 145                             sizeof(buf) - incoming_stream.avail_out);
 146                         break;
 147                 case Z_BUF_ERROR:
 148                         /*
 149                          * Comments in zlib.h say that we should keep calling
 150                          * inflate() until we get an error.  This appears to
 151                          * be the error that we get.
 152                          */
 153                         return;
 154                 default:
 155                         inflate_failed = 1;
 156                         fatal("buffer_uncompress: inflate returned %d", status);
 157                         /* NOTREACHED */
 158                 }
 159         }
 160 }