1 /* 2 * Copyright (c) 1988, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * @(#)ring.c 8.2 (Berkeley) 5/30/95 34 * $FreeBSD: src/crypto/telnet/telnet/ring.c,v 1.2.8.2 2002/04/13 10:59:08 markm Exp $ 35 */ 36 37 /* 38 * This defines a structure for a ring buffer. 39 * 40 * The circular buffer has two parts: 41 *((( 42 * full: [consume, supply) 43 * empty: [supply, consume) 44 *]]] 45 * 46 */ 47 48 #include <errno.h> 49 #include <stdio.h> 50 #include <string.h> 51 52 #ifdef size_t 53 #undef size_t 54 #endif 55 56 #include <sys/types.h> 57 #ifndef FILIO_H 58 #include <sys/ioctl.h> 59 #endif 60 #include <sys/socket.h> 61 62 #include "ring.h" 63 #include "general.h" 64 65 /* Internal macros */ 66 67 #if !defined(MIN) 68 #define MIN(a,b) (((a)<(b))? (a):(b)) 69 #endif /* !defined(MIN) */ 70 71 #define ring_subtract(d,a,b) (((a)-(b) >= 0)? \ 72 (a)-(b): (((a)-(b))+(d)->size)) 73 74 #define ring_increment(d,a,c) (((a)+(c) < (d)->top)? \ 75 (a)+(c) : (((a)+(c))-(d)->size)) 76 77 #define ring_decrement(d,a,c) (((a)-(c) >= (d)->bottom)? \ 78 (a)-(c) : (((a)-(c))-(d)->size)) 79 80 81 /* 82 * The following is a clock, used to determine full, empty, etc. 83 * 84 * There is some trickiness here. Since the ring buffers are initialized 85 * to ZERO on allocation, we need to make sure, when interpreting the 86 * clock, that when the times are EQUAL, then the buffer is FULL. 87 */ 88 static u_long ring_clock = 0; 89 90 91 #define ring_empty(d) (((d)->consume == (d)->supply) && \ 92 ((d)->consumetime >= (d)->supplytime)) 93 #define ring_full(d) (((d)->supply == (d)->consume) && \ 94 ((d)->supplytime > (d)->consumetime)) 95 96 /* Buffer state transition routines */ 97 98 int 99 ring_init(Ring *ring, unsigned char *buffer, int count) 100 { 101 memset((char *)ring, 0, sizeof *ring); 102 103 ring->size = count; 104 105 ring->supply = ring->consume = ring->bottom = buffer; 106 107 ring->top = ring->bottom+ring->size; 108 109 #ifdef ENCRYPTION 110 ring->clearto = 0; 111 #endif /* ENCRYPTION */ 112 113 return 1; 114 } 115 116 /* Mark routines */ 117 118 /* 119 * Mark the most recently supplied byte. 120 */ 121 122 void 123 ring_mark(Ring *ring) 124 { 125 ring->mark = ring_decrement(ring, ring->supply, 1); 126 } 127 128 /* 129 * Is the ring pointing to the mark? 130 */ 131 132 int 133 ring_at_mark(Ring *ring) 134 { 135 if (ring->mark == ring->consume) { 136 return 1; 137 } else { 138 return 0; 139 } 140 } 141 142 /* 143 * Clear any mark set on the ring. 144 */ 145 146 void 147 ring_clear_mark(Ring *ring) 148 { 149 ring->mark = 0; 150 } 151 152 /* 153 * Add characters from current segment to ring buffer. 154 */ 155 void 156 ring_supplied(Ring *ring, int count) 157 { 158 ring->supply = ring_increment(ring, ring->supply, count); 159 ring->supplytime = ++ring_clock; 160 } 161 162 /* 163 * We have just consumed "c" bytes. 164 */ 165 void 166 ring_consumed(Ring *ring, int count) 167 { 168 if (count == 0) /* don't update anything */ 169 return; 170 171 if (ring->mark && 172 (ring_subtract(ring, ring->mark, ring->consume) < count)) { 173 ring->mark = 0; 174 } 175 #ifdef ENCRYPTION 176 if (ring->consume < ring->clearto && 177 ring->clearto <= ring->consume + count) 178 ring->clearto = 0; 179 else if (ring->consume + count > ring->top && 180 ring->bottom <= ring->clearto && 181 ring->bottom + ((ring->consume + count) - ring->top)) 182 ring->clearto = 0; 183 #endif /* ENCRYPTION */ 184 ring->consume = ring_increment(ring, ring->consume, count); 185 ring->consumetime = ++ring_clock; 186 /* 187 * Try to encourage "ring_empty_consecutive()" to be large. 188 */ 189 if (ring_empty(ring)) { 190 ring->consume = ring->supply = ring->bottom; 191 } 192 } 193 194 195 196 /* Buffer state query routines */ 197 198 199 /* Number of bytes that may be supplied */ 200 int 201 ring_empty_count(Ring *ring) 202 { 203 if (ring_empty(ring)) { /* if empty */ 204 return ring->size; 205 } else { 206 return ring_subtract(ring, ring->consume, ring->supply); 207 } 208 } 209 210 /* number of CONSECUTIVE bytes that may be supplied */ 211 int 212 ring_empty_consecutive(Ring *ring) 213 { 214 if ((ring->consume < ring->supply) || ring_empty(ring)) { 215 /* 216 * if consume is "below" supply, or empty, then 217 * return distance to the top 218 */ 219 return ring_subtract(ring, ring->top, ring->supply); 220 } else { 221 /* 222 * else, return what we may. 223 */ 224 return ring_subtract(ring, ring->consume, ring->supply); 225 } 226 } 227 228 /* Return the number of bytes that are available for consuming 229 * (but don't give more than enough to get to cross over set mark) 230 */ 231 232 int 233 ring_full_count(Ring *ring) 234 { 235 if ((ring->mark == 0) || (ring->mark == ring->consume)) { 236 if (ring_full(ring)) { 237 return ring->size; /* nothing consumed, but full */ 238 } else { 239 return ring_subtract(ring, ring->supply, ring->consume); 240 } 241 } else { 242 return ring_subtract(ring, ring->mark, ring->consume); 243 } 244 } 245 246 /* 247 * Return the number of CONSECUTIVE bytes available for consuming. 248 * However, don't return more than enough to cross over set mark. 249 */ 250 int 251 ring_full_consecutive(Ring *ring) 252 { 253 if ((ring->mark == 0) || (ring->mark == ring->consume)) { 254 if ((ring->supply < ring->consume) || ring_full(ring)) { 255 return ring_subtract(ring, ring->top, ring->consume); 256 } else { 257 return ring_subtract(ring, ring->supply, ring->consume); 258 } 259 } else { 260 if (ring->mark < ring->consume) { 261 return ring_subtract(ring, ring->top, ring->consume); 262 } else { /* Else, distance to mark */ 263 return ring_subtract(ring, ring->mark, ring->consume); 264 } 265 } 266 } 267 268 /* 269 * Move data into the "supply" portion of of the ring buffer. 270 */ 271 void 272 ring_supply_data(Ring *ring, unsigned char *buffer, int count) 273 { 274 int i; 275 276 while (count) { 277 i = MIN(count, ring_empty_consecutive(ring)); 278 memcpy(ring->supply, buffer, i); 279 ring_supplied(ring, i); 280 count -= i; 281 buffer += i; 282 } 283 } 284 285 #ifdef ENCRYPTION 286 void 287 ring_encrypt(Ring *ring, void (*encryptor)(unsigned char *, int)) 288 { 289 unsigned char *s, *c; 290 291 if (ring_empty(ring) || ring->clearto == ring->supply) 292 return; 293 294 if (!(c = ring->clearto)) 295 c = ring->consume; 296 297 s = ring->supply; 298 299 if (s <= c) { 300 (*encryptor)(c, ring->top - c); 301 (*encryptor)(ring->bottom, s - ring->bottom); 302 } else 303 (*encryptor)(c, s - c); 304 305 ring->clearto = ring->supply; 306 } 307 308 void 309 ring_clearto(Ring *ring) 310 { 311 if (!ring_empty(ring)) 312 ring->clearto = ring->supply; 313 else 314 ring->clearto = 0; 315 } 316 #endif /* ENCRYPTION */ 317