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 #pragma ident "%Z%%M% %I% %E% SMI" 18 19 #include "log.h" 20 #include "buffer.h" 21 #include "zlib.h" 22 #include "compress.h" 23 24 z_stream incoming_stream; 25 z_stream outgoing_stream; 26 static int compress_init_send_called = 0; 27 static int compress_init_recv_called = 0; 28 static int inflate_failed = 0; 29 static int deflate_failed = 0; 30 31 /* 32 * Initializes compression; level is compression level from 1 to 9 33 * (as in gzip). 34 */ 35 36 void 37 buffer_compress_init_send(int level) 38 { 39 if (compress_init_send_called == 1) 40 deflateEnd(&outgoing_stream); 41 compress_init_send_called = 1; 42 debug("Enabling compression at level %d.", level); 43 if (level < 1 || level > 9) 44 fatal("Bad compression level %d.", level); 45 deflateInit(&outgoing_stream, level); 46 } 47 void 48 buffer_compress_init_recv(void) 49 { 50 if (compress_init_recv_called == 1) 51 inflateEnd(&incoming_stream); 52 compress_init_recv_called = 1; 53 inflateInit(&incoming_stream); 54 } 55 56 /* Frees any data structures allocated for compression. */ 57 58 void 59 buffer_compress_uninit(void) 60 { 61 debug("compress outgoing: raw data %lu, compressed %lu, factor %.2f", 62 outgoing_stream.total_in, outgoing_stream.total_out, 63 outgoing_stream.total_in == 0 ? 0.0 : 64 (double) outgoing_stream.total_out / outgoing_stream.total_in); 65 debug("compress incoming: raw data %lu, compressed %lu, factor %.2f", 66 incoming_stream.total_out, incoming_stream.total_in, 67 incoming_stream.total_out == 0 ? 0.0 : 68 (double) incoming_stream.total_in / incoming_stream.total_out); 69 if (compress_init_recv_called == 1 && inflate_failed == 0) 70 inflateEnd(&incoming_stream); 71 if (compress_init_send_called == 1 && deflate_failed == 0) 72 deflateEnd(&outgoing_stream); 73 } 74 75 /* 76 * Compresses the contents of input_buffer into output_buffer. All packets 77 * compressed using this function will form a single compressed data stream; 78 * however, data will be flushed at the end of every call so that each 79 * output_buffer can be decompressed independently (but in the appropriate 80 * order since they together form a single compression stream) by the 81 * receiver. This appends the compressed data to the output buffer. 82 */ 83 84 void 85 buffer_compress(Buffer * input_buffer, Buffer * output_buffer) 86 { 87 u_char buf[4096]; 88 int status; 89 90 /* This case is not handled below. */ 91 if (buffer_len(input_buffer) == 0) 92 return; 93 94 /* Input is the contents of the input buffer. */ 95 outgoing_stream.next_in = buffer_ptr(input_buffer); 96 outgoing_stream.avail_in = buffer_len(input_buffer); 97 98 /* Loop compressing until deflate() returns with avail_out != 0. */ 99 do { 100 /* Set up fixed-size output buffer. */ 101 outgoing_stream.next_out = buf; 102 outgoing_stream.avail_out = sizeof(buf); 103 104 /* Compress as much data into the buffer as possible. */ 105 status = deflate(&outgoing_stream, Z_PARTIAL_FLUSH); 106 switch (status) { 107 case Z_OK: 108 /* Append compressed data to output_buffer. */ 109 buffer_append(output_buffer, buf, 110 sizeof(buf) - outgoing_stream.avail_out); 111 break; 112 default: 113 deflate_failed = 1; 114 fatal("buffer_compress: deflate returned %d", status); 115 /* NOTREACHED */ 116 } 117 } while (outgoing_stream.avail_out == 0); 118 } 119 120 /* 121 * Uncompresses the contents of input_buffer into output_buffer. All packets 122 * uncompressed using this function will form a single compressed data 123 * stream; however, data will be flushed at the end of every call so that 124 * each output_buffer. This must be called for the same size units that the 125 * buffer_compress was called, and in the same order that buffers compressed 126 * with that. This appends the uncompressed data to the output buffer. 127 */ 128 129 void 130 buffer_uncompress(Buffer * input_buffer, Buffer * output_buffer) 131 { 132 u_char buf[4096]; 133 int status; 134 135 incoming_stream.next_in = buffer_ptr(input_buffer); 136 incoming_stream.avail_in = buffer_len(input_buffer); 137 138 for (;;) { 139 /* Set up fixed-size output buffer. */ 140 incoming_stream.next_out = buf; 141 incoming_stream.avail_out = sizeof(buf); 142 143 status = inflate(&incoming_stream, Z_PARTIAL_FLUSH); 144 switch (status) { 145 case Z_OK: 146 buffer_append(output_buffer, buf, 147 sizeof(buf) - incoming_stream.avail_out); 148 break; 149 case Z_BUF_ERROR: 150 /* 151 * Comments in zlib.h say that we should keep calling 152 * inflate() until we get an error. This appears to 153 * be the error that we get. 154 */ 155 return; 156 default: 157 inflate_failed = 1; 158 fatal("buffer_uncompress: inflate returned %d", status); 159 /* NOTREACHED */ 160 } 161 } 162 } 163