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 * $DragonFly: src/crypto/telnet/telnet/ring.c,v 1.2 2003/06/17 04:24:37 dillon Exp $ 36 */ 37 38 /* 39 * This defines a structure for a ring buffer. 40 * 41 * The circular buffer has two parts: 42 *((( 43 * full: [consume, supply) 44 * empty: [supply, consume) 45 *]]] 46 * 47 */ 48 49 #include <errno.h> 50 #include <stdio.h> 51 #include <string.h> 52 53 #ifdef size_t 54 #undef size_t 55 #endif 56 57 #include <sys/types.h> 58 #ifndef FILIO_H 59 #include <sys/ioctl.h> 60 #endif 61 #include <sys/socket.h> 62 63 #include "ring.h" 64 #include "general.h" 65 66 /* Internal macros */ 67 68 #if !defined(MIN) 69 #define MIN(a,b) (((a)<(b))? (a):(b)) 70 #endif /* !defined(MIN) */ 71 72 #define ring_subtract(d,a,b) (((a)-(b) >= 0)? \ 73 (a)-(b): (((a)-(b))+(d)->size)) 74 75 #define ring_increment(d,a,c) (((a)+(c) < (d)->top)? \ 76 (a)+(c) : (((a)+(c))-(d)->size)) 77 78 #define ring_decrement(d,a,c) (((a)-(c) >= (d)->bottom)? \ 79 (a)-(c) : (((a)-(c))-(d)->size)) 80 81 82 /* 83 * The following is a clock, used to determine full, empty, etc. 84 * 85 * There is some trickiness here. Since the ring buffers are initialized 86 * to ZERO on allocation, we need to make sure, when interpreting the 87 * clock, that when the times are EQUAL, then the buffer is FULL. 88 */ 89 static u_long ring_clock = 0; 90 91 92 #define ring_empty(d) (((d)->consume == (d)->supply) && \ 93 ((d)->consumetime >= (d)->supplytime)) 94 #define ring_full(d) (((d)->supply == (d)->consume) && \ 95 ((d)->supplytime > (d)->consumetime)) 96 97 /* Buffer state transition routines */ 98 99 int 100 ring_init(Ring *ring, unsigned char *buffer, int count) 101 { 102 memset((char *)ring, 0, sizeof *ring); 103 104 ring->size = count; 105 106 ring->supply = ring->consume = ring->bottom = buffer; 107 108 ring->top = ring->bottom+ring->size; 109 110 #ifdef ENCRYPTION 111 ring->clearto = 0; 112 #endif /* ENCRYPTION */ 113 114 return 1; 115 } 116 117 /* Mark routines */ 118 119 /* 120 * Mark the most recently supplied byte. 121 */ 122 123 void 124 ring_mark(Ring *ring) 125 { 126 ring->mark = ring_decrement(ring, ring->supply, 1); 127 } 128 129 /* 130 * Is the ring pointing to the mark? 131 */ 132 133 int 134 ring_at_mark(Ring *ring) 135 { 136 if (ring->mark == ring->consume) { 137 return 1; 138 } else { 139 return 0; 140 } 141 } 142 143 /* 144 * Clear any mark set on the ring. 145 */ 146 147 void 148 ring_clear_mark(Ring *ring) 149 { 150 ring->mark = 0; 151 } 152 153 /* 154 * Add characters from current segment to ring buffer. 155 */ 156 void 157 ring_supplied(Ring *ring, int count) 158 { 159 ring->supply = ring_increment(ring, ring->supply, count); 160 ring->supplytime = ++ring_clock; 161 } 162 163 /* 164 * We have just consumed "c" bytes. 165 */ 166 void 167 ring_consumed(Ring *ring, int count) 168 { 169 if (count == 0) /* don't update anything */ 170 return; 171 172 if (ring->mark && 173 (ring_subtract(ring, ring->mark, ring->consume) < count)) { 174 ring->mark = 0; 175 } 176 #ifdef ENCRYPTION 177 if (ring->consume < ring->clearto && 178 ring->clearto <= ring->consume + count) 179 ring->clearto = 0; 180 else if (ring->consume + count > ring->top && 181 ring->bottom <= ring->clearto && 182 ring->bottom + ((ring->consume + count) - ring->top)) 183 ring->clearto = 0; 184 #endif /* ENCRYPTION */ 185 ring->consume = ring_increment(ring, ring->consume, count); 186 ring->consumetime = ++ring_clock; 187 /* 188 * Try to encourage "ring_empty_consecutive()" to be large. 189 */ 190 if (ring_empty(ring)) { 191 ring->consume = ring->supply = ring->bottom; 192 } 193 } 194 195 196 197 /* Buffer state query routines */ 198 199 200 /* Number of bytes that may be supplied */ 201 int 202 ring_empty_count(Ring *ring) 203 { 204 if (ring_empty(ring)) { /* if empty */ 205 return ring->size; 206 } else { 207 return ring_subtract(ring, ring->consume, ring->supply); 208 } 209 } 210 211 /* number of CONSECUTIVE bytes that may be supplied */ 212 int 213 ring_empty_consecutive(Ring *ring) 214 { 215 if ((ring->consume < ring->supply) || ring_empty(ring)) { 216 /* 217 * if consume is "below" supply, or empty, then 218 * return distance to the top 219 */ 220 return ring_subtract(ring, ring->top, ring->supply); 221 } else { 222 /* 223 * else, return what we may. 224 */ 225 return ring_subtract(ring, ring->consume, ring->supply); 226 } 227 } 228 229 /* Return the number of bytes that are available for consuming 230 * (but don't give more than enough to get to cross over set mark) 231 */ 232 233 int 234 ring_full_count(Ring *ring) 235 { 236 if ((ring->mark == 0) || (ring->mark == ring->consume)) { 237 if (ring_full(ring)) { 238 return ring->size; /* nothing consumed, but full */ 239 } else { 240 return ring_subtract(ring, ring->supply, ring->consume); 241 } 242 } else { 243 return ring_subtract(ring, ring->mark, ring->consume); 244 } 245 } 246 247 /* 248 * Return the number of CONSECUTIVE bytes available for consuming. 249 * However, don't return more than enough to cross over set mark. 250 */ 251 int 252 ring_full_consecutive(Ring *ring) 253 { 254 if ((ring->mark == 0) || (ring->mark == ring->consume)) { 255 if ((ring->supply < ring->consume) || ring_full(ring)) { 256 return ring_subtract(ring, ring->top, ring->consume); 257 } else { 258 return ring_subtract(ring, ring->supply, ring->consume); 259 } 260 } else { 261 if (ring->mark < ring->consume) { 262 return ring_subtract(ring, ring->top, ring->consume); 263 } else { /* Else, distance to mark */ 264 return ring_subtract(ring, ring->mark, ring->consume); 265 } 266 } 267 } 268 269 /* 270 * Move data into the "supply" portion of of the ring buffer. 271 */ 272 void 273 ring_supply_data(Ring *ring, unsigned char *buffer, int count) 274 { 275 int i; 276 277 while (count) { 278 i = MIN(count, ring_empty_consecutive(ring)); 279 memcpy(ring->supply, buffer, i); 280 ring_supplied(ring, i); 281 count -= i; 282 buffer += i; 283 } 284 } 285 286 #ifdef ENCRYPTION 287 void 288 ring_encrypt(Ring *ring, void (*encryptor)(unsigned char *, int)) 289 { 290 unsigned char *s, *c; 291 292 if (ring_empty(ring) || ring->clearto == ring->supply) 293 return; 294 295 if (!(c = ring->clearto)) 296 c = ring->consume; 297 298 s = ring->supply; 299 300 if (s <= c) { 301 (*encryptor)(c, ring->top - c); 302 (*encryptor)(ring->bottom, s - ring->bottom); 303 } else 304 (*encryptor)(c, s - c); 305 306 ring->clearto = ring->supply; 307 } 308 309 void 310 ring_clearto(ring) 311 Ring *ring; 312 { 313 if (!ring_empty(ring)) 314 ring->clearto = ring->supply; 315 else 316 ring->clearto = 0; 317 } 318 #endif /* ENCRYPTION */ 319