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