1 /* $OpenBSD: compress.c,v 1.26 2010/09/08 04:13:31 deraadt Exp $ */ 2 /* 3 * Author: Tatu Ylonen <ylo (at) cs.hut.fi> 4 * Copyright (c) 1995 Tatu Ylonen <ylo (at) cs.hut.fi>, Espoo, Finland 5 * All rights reserved 6 * Interface to packet compression for ssh. 7 * 8 * As far as I am concerned, the code I have written for this software 9 * can be used freely for any purpose. Any derived versions of this 10 * software must be clearly marked as such, and if the derived work is 11 * incompatible with the protocol description in the RFC file, it must be 12 * called by a name other than "ssh" or "Secure Shell". 13 */ 14 15 #include "includes.h" 16 17 #include <sys/types.h> 18 19 #include <stdarg.h> 20 21 #include "log.h" 22 #include "buffer.h" 23 #include "compress.h" 24 25 #include <zlib.h> 26 27 z_stream incoming_stream; 28 z_stream outgoing_stream; 29 static int compress_init_send_called = 0; 30 static int compress_init_recv_called = 0; 31 static int inflate_failed = 0; 32 static int deflate_failed = 0; 33 34 /* 35 * Initializes compression; level is compression level from 1 to 9 36 * (as in gzip). 37 */ 38 39 void 40 buffer_compress_init_send(int level) 41 { 42 if (compress_init_send_called == 1) 43 deflateEnd(&outgoing_stream); 44 compress_init_send_called = 1; 45 debug("Enabling compression at level %d.", level); 46 if (level < 1 || level > 9) 47 fatal("Bad compression level %d.", level); 48 deflateInit(&outgoing_stream, level); 49 } 50 void 51 buffer_compress_init_recv(void) 52 { 53 if (compress_init_recv_called == 1) 54 inflateEnd(&incoming_stream); 55 compress_init_recv_called = 1; 56 inflateInit(&incoming_stream); 57 } 58 59 /* Frees any data structures allocated for compression. */ 60 61 void 62 buffer_compress_uninit(void) 63 { 64 debug("compress outgoing: raw data %llu, compressed %llu, factor %.2f", 65 (unsigned long long)outgoing_stream.total_in, 66 (unsigned long long)outgoing_stream.total_out, 67 outgoing_stream.total_in == 0 ? 0.0 : 68 (double) outgoing_stream.total_out / outgoing_stream.total_in); 69 debug("compress incoming: raw data %llu, compressed %llu, factor %.2f", 70 (unsigned long long)incoming_stream.total_out, 71 (unsigned long long)incoming_stream.total_in, 72 incoming_stream.total_out == 0 ? 0.0 : 73 (double) incoming_stream.total_in / incoming_stream.total_out); 74 if (compress_init_recv_called == 1 && inflate_failed == 0) 75 inflateEnd(&incoming_stream); 76 if (compress_init_send_called == 1 && deflate_failed == 0) 77 deflateEnd(&outgoing_stream); 78 } 79 80 /* 81 * Compresses the contents of input_buffer into output_buffer. All packets 82 * compressed using this function will form a single compressed data stream; 83 * however, data will be flushed at the end of every call so that each 84 * output_buffer can be decompressed independently (but in the appropriate 85 * order since they together form a single compression stream) by the 86 * receiver. This appends the compressed data to the output buffer. 87 */ 88 89 void 90 buffer_compress(Buffer * input_buffer, Buffer * output_buffer) 91 { 92 u_char buf[4096]; 93 int status; 94 95 /* This case is not handled below. */ 96 if (buffer_len(input_buffer) == 0) 97 return; 98 99 /* Input is the contents of the input buffer. */ 100 outgoing_stream.next_in = buffer_ptr(input_buffer); 101 outgoing_stream.avail_in = buffer_len(input_buffer); 102 103 /* Loop compressing until deflate() returns with avail_out != 0. */ 104 do { 105 /* Set up fixed-size output buffer. */ 106 outgoing_stream.next_out = buf; 107 outgoing_stream.avail_out = sizeof(buf); 108 109 /* Compress as much data into the buffer as possible. */ 110 status = deflate(&outgoing_stream, Z_PARTIAL_FLUSH); 111 switch (status) { 112 case Z_OK: 113 /* Append compressed data to output_buffer. */ 114 buffer_append(output_buffer, buf, 115 sizeof(buf) - outgoing_stream.avail_out); 116 break; 117 default: 118 deflate_failed = 1; 119 fatal("buffer_compress: deflate returned %d", status); 120 /* NOTREACHED */ 121 } 122 } while (outgoing_stream.avail_out == 0); 123 } 124 125 /* 126 * Uncompresses the contents of input_buffer into output_buffer. All packets 127 * uncompressed using this function will form a single compressed data 128 * stream; however, data will be flushed at the end of every call so that 129 * each output_buffer. This must be called for the same size units that the 130 * buffer_compress was called, and in the same order that buffers compressed 131 * with that. This appends the uncompressed data to the output buffer. 132 */ 133 134 void 135 buffer_uncompress(Buffer * input_buffer, Buffer * output_buffer) 136 { 137 u_char buf[4096]; 138 int status; 139 140 incoming_stream.next_in = buffer_ptr(input_buffer); 141 incoming_stream.avail_in = buffer_len(input_buffer); 142 143 for (;;) { 144 /* Set up fixed-size output buffer. */ 145 incoming_stream.next_out = buf; 146 incoming_stream.avail_out = sizeof(buf); 147 148 status = inflate(&incoming_stream, Z_PARTIAL_FLUSH); 149 switch (status) { 150 case Z_OK: 151 buffer_append(output_buffer, buf, 152 sizeof(buf) - incoming_stream.avail_out); 153 break; 154 case Z_BUF_ERROR: 155 /* 156 * Comments in zlib.h say that we should keep calling 157 * inflate() until we get an error. This appears to 158 * be the error that we get. 159 */ 160 return; 161 default: 162 inflate_failed = 1; 163 fatal("buffer_uncompress: inflate returned %d", status); 164 /* NOTREACHED */ 165 } 166 } 167 } 168
