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 34 #if 0 35 #ifndef lint 36 static const char sccsid[] = "@(#)ring.c 8.2 (Berkeley) 5/30/95"; 37 #endif 38 #endif 39 #include <sys/cdefs.h> 40 __FBSDID("$FreeBSD$"); 41 42 /* 43 * This defines a structure for a ring buffer. 44 * 45 * The circular buffer has two parts: 46 *((( 47 * full: [consume, supply) 48 * empty: [supply, consume) 49 *]]] 50 * 51 */ 52 53 #include <errno.h> 54 #include <stdio.h> 55 #include <string.h> 56 57 #ifdef size_t 58 #undef size_t 59 #endif 60 61 #include <sys/types.h> 62 #ifndef FILIO_H 63 #include <sys/ioctl.h> 64 #endif 65 #include <sys/socket.h> 66 67 #include "ring.h" 68 #include "general.h" 69 70 /* Internal macros */ 71 72 #if !defined(MIN) 73 #define MIN(a,b) (((a)<(b))? (a):(b)) 74 #endif /* !defined(MIN) */ 75 76 #define ring_subtract(d,a,b) (((a)-(b) >= 0)? \ 77 (a)-(b): (((a)-(b))+(d)->size)) 78 79 #define ring_increment(d,a,c) (((a)+(c) < (d)->top)? \ 80 (a)+(c) : (((a)+(c))-(d)->size)) 81 82 #define ring_decrement(d,a,c) (((a)-(c) >= (d)->bottom)? \ 83 (a)-(c) : (((a)-(c))-(d)->size)) 84 85 86 /* 87 * The following is a clock, used to determine full, empty, etc. 88 * 89 * There is some trickiness here. Since the ring buffers are initialized 90 * to ZERO on allocation, we need to make sure, when interpreting the 91 * clock, that when the times are EQUAL, then the buffer is FULL. 92 */ 93 static u_long ring_clock = 0; 94 95 96 #define ring_empty(d) (((d)->consume == (d)->supply) && \ 97 ((d)->consumetime >= (d)->supplytime)) 98 #define ring_full(d) (((d)->supply == (d)->consume) && \ 99 ((d)->supplytime > (d)->consumetime)) 100 101 /* Buffer state transition routines */ 102 103 int 104 ring_init(Ring *ring, unsigned char *buffer, int count) 105 { 106 memset((char *)ring, 0, sizeof *ring); 107 108 ring->size = count; 109 110 ring->supply = ring->consume = ring->bottom = buffer; 111 112 ring->top = ring->bottom+ring->size; 113 114 #ifdef ENCRYPTION 115 ring->clearto = 0; 116 #endif /* ENCRYPTION */ 117 118 return 1; 119 } 120 121 /* Mark routines */ 122 123 /* 124 * Mark the most recently supplied byte. 125 */ 126 127 void 128 ring_mark(Ring *ring) 129 { 130 ring->mark = ring_decrement(ring, ring->supply, 1); 131 } 132 133 /* 134 * Is the ring pointing to the mark? 135 */ 136 137 int 138 ring_at_mark(Ring *ring) 139 { 140 if (ring->mark == ring->consume) { 141 return 1; 142 } else { 143 return 0; 144 } 145 } 146 147 /* 148 * Clear any mark set on the ring. 149 */ 150 151 void 152 ring_clear_mark(Ring *ring) 153 { 154 ring->mark = 0; 155 } 156 157 /* 158 * Add characters from current segment to ring buffer. 159 */ 160 void 161 ring_supplied(Ring *ring, int count) 162 { 163 ring->supply = ring_increment(ring, ring->supply, count); 164 ring->supplytime = ++ring_clock; 165 } 166 167 /* 168 * We have just consumed "c" bytes. 169 */ 170 void 171 ring_consumed(Ring *ring, int count) 172 { 173 if (count == 0) /* don't update anything */ 174 return; 175 176 if (ring->mark && 177 (ring_subtract(ring, ring->mark, ring->consume) < count)) { 178 ring->mark = 0; 179 } 180 #ifdef ENCRYPTION 181 if (ring->consume < ring->clearto && 182 ring->clearto <= ring->consume + count) 183 ring->clearto = 0; 184 else if (ring->consume + count > ring->top && 185 ring->bottom <= ring->clearto && 186 ring->bottom + ((ring->consume + count) - ring->top)) 187 ring->clearto = 0; 188 #endif /* ENCRYPTION */ 189 ring->consume = ring_increment(ring, ring->consume, count); 190 ring->consumetime = ++ring_clock; 191 /* 192 * Try to encourage "ring_empty_consecutive()" to be large. 193 */ 194 if (ring_empty(ring)) { 195 ring->consume = ring->supply = ring->bottom; 196 } 197 } 198 199 200 201 /* Buffer state query routines */ 202 203 204 /* Number of bytes that may be supplied */ 205 int 206 ring_empty_count(Ring *ring) 207 { 208 if (ring_empty(ring)) { /* if empty */ 209 return ring->size; 210 } else { 211 return ring_subtract(ring, ring->consume, ring->supply); 212 } 213 } 214 215 /* number of CONSECUTIVE bytes that may be supplied */ 216 int 217 ring_empty_consecutive(Ring *ring) 218 { 219 if ((ring->consume < ring->supply) || ring_empty(ring)) { 220 /* 221 * if consume is "below" supply, or empty, then 222 * return distance to the top 223 */ 224 return ring_subtract(ring, ring->top, ring->supply); 225 } else { 226 /* 227 * else, return what we may. 228 */ 229 return ring_subtract(ring, ring->consume, ring->supply); 230 } 231 } 232 233 /* Return the number of bytes that are available for consuming 234 * (but don't give more than enough to get to cross over set mark) 235 */ 236 237 int 238 ring_full_count(Ring *ring) 239 { 240 if ((ring->mark == 0) || (ring->mark == ring->consume)) { 241 if (ring_full(ring)) { 242 return ring->size; /* nothing consumed, but full */ 243 } else { 244 return ring_subtract(ring, ring->supply, ring->consume); 245 } 246 } else { 247 return ring_subtract(ring, ring->mark, ring->consume); 248 } 249 } 250 251 /* 252 * Return the number of CONSECUTIVE bytes available for consuming. 253 * However, don't return more than enough to cross over set mark. 254 */ 255 int 256 ring_full_consecutive(Ring *ring) 257 { 258 if ((ring->mark == 0) || (ring->mark == ring->consume)) { 259 if ((ring->supply < ring->consume) || ring_full(ring)) { 260 return ring_subtract(ring, ring->top, ring->consume); 261 } else { 262 return ring_subtract(ring, ring->supply, ring->consume); 263 } 264 } else { 265 if (ring->mark < ring->consume) { 266 return ring_subtract(ring, ring->top, ring->consume); 267 } else { /* Else, distance to mark */ 268 return ring_subtract(ring, ring->mark, ring->consume); 269 } 270 } 271 } 272 273 /* 274 * Move data into the "supply" portion of of the ring buffer. 275 */ 276 void 277 ring_supply_data(Ring *ring, unsigned char *buffer, int count) 278 { 279 int i; 280 281 while (count) { 282 i = MIN(count, ring_empty_consecutive(ring)); 283 memcpy(ring->supply, buffer, i); 284 ring_supplied(ring, i); 285 count -= i; 286 buffer += i; 287 } 288 } 289 290 #ifdef ENCRYPTION 291 void 292 ring_encrypt(Ring *ring, void (*encryptor)(unsigned char *, int)) 293 { 294 unsigned char *s, *c; 295 296 if (ring_empty(ring) || ring->clearto == ring->supply) 297 return; 298 299 if (!(c = ring->clearto)) 300 c = ring->consume; 301 302 s = ring->supply; 303 304 if (s <= c) { 305 (*encryptor)(c, ring->top - c); 306 (*encryptor)(ring->bottom, s - ring->bottom); 307 } else 308 (*encryptor)(c, s - c); 309 310 ring->clearto = ring->supply; 311 } 312 313 void 314 ring_clearto(ring) 315 Ring *ring; 316 { 317 if (!ring_empty(ring)) 318 ring->clearto = ring->supply; 319 else 320 ring->clearto = 0; 321 } 322 #endif /* ENCRYPTION */ 323