/* * Copyright (c) 1988, 1993 * The Regents of the University of California. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #include #ifdef __FBSDID __FBSDID("$FreeBSD: src/crypto/telnet/telnet/ring.c,v 1.2.8.2 2002/04/13 10:59:08 markm Exp $"); #endif #ifndef lint static const char sccsid[] = "@(#)ring.c 8.2 (Berkeley) 5/30/95"; #endif /* * This defines a structure for a ring buffer. * * The circular buffer has two parts: *((( * full: [consume, supply) * empty: [supply, consume) *]]] * */ #include #include #include #ifdef size_t #undef size_t #endif #include #ifndef FILIO_H #include #endif #include #include "ring.h" #include "general.h" /* Internal macros */ #if !defined(MIN) #define MIN(a,b) (((a)<(b))? (a):(b)) #endif /* !defined(MIN) */ #define ring_subtract(d,a,b) (((a)-(b) >= 0)? \ (a)-(b): (((a)-(b))+(d)->size)) #define ring_increment(d,a,c) (((a)+(c) < (d)->top)? \ (a)+(c) : (((a)+(c))-(d)->size)) #define ring_decrement(d,a,c) (((a)-(c) >= (d)->bottom)? \ (a)-(c) : (((a)-(c))-(d)->size)) /* * The following is a clock, used to determine full, empty, etc. * * There is some trickiness here. Since the ring buffers are initialized * to ZERO on allocation, we need to make sure, when interpreting the * clock, that when the times are EQUAL, then the buffer is FULL. */ static u_long ring_clock = 0; #define ring_empty(d) (((d)->consume == (d)->supply) && \ ((d)->consumetime >= (d)->supplytime)) #define ring_full(d) (((d)->supply == (d)->consume) && \ ((d)->supplytime > (d)->consumetime)) /* Buffer state transition routines */ int ring_init(Ring *ring, unsigned char *buffer, int count) { memset((char *)ring, 0, sizeof *ring); ring->size = count; ring->supply = ring->consume = ring->bottom = buffer; ring->top = ring->bottom+ring->size; #ifdef ENCRYPTION ring->clearto = 0; #endif /* ENCRYPTION */ return 1; } /* Mark routines */ /* * Mark the most recently supplied byte. */ void ring_mark(Ring *ring) { ring->mark = ring_decrement(ring, ring->supply, 1); } /* * Is the ring pointing to the mark? */ int ring_at_mark(Ring *ring) { if (ring->mark == ring->consume) { return 1; } else { return 0; } } /* * Clear any mark set on the ring. */ void ring_clear_mark(Ring *ring) { ring->mark = 0; } /* * Add characters from current segment to ring buffer. */ void ring_supplied(Ring *ring, int count) { ring->supply = ring_increment(ring, ring->supply, count); ring->supplytime = ++ring_clock; } /* * We have just consumed "c" bytes. */ void ring_consumed(Ring *ring, int count) { if (count == 0) /* don't update anything */ return; if (ring->mark && (ring_subtract(ring, ring->mark, ring->consume) < count)) { ring->mark = 0; } #ifdef ENCRYPTION if (ring->consume < ring->clearto && ring->clearto <= ring->consume + count) ring->clearto = 0; else if (ring->consume + count > ring->top && ring->bottom <= ring->clearto && ring->bottom + ((ring->consume + count) - ring->top)) ring->clearto = 0; #endif /* ENCRYPTION */ ring->consume = ring_increment(ring, ring->consume, count); ring->consumetime = ++ring_clock; /* * Try to encourage "ring_empty_consecutive()" to be large. */ if (ring_empty(ring)) { ring->consume = ring->supply = ring->bottom; } } /* Buffer state query routines */ /* Number of bytes that may be supplied */ int ring_empty_count(Ring *ring) { if (ring_empty(ring)) { /* if empty */ return ring->size; } else { return ring_subtract(ring, ring->consume, ring->supply); } } /* number of CONSECUTIVE bytes that may be supplied */ int ring_empty_consecutive(Ring *ring) { if ((ring->consume < ring->supply) || ring_empty(ring)) { /* * if consume is "below" supply, or empty, then * return distance to the top */ return ring_subtract(ring, ring->top, ring->supply); } else { /* * else, return what we may. */ return ring_subtract(ring, ring->consume, ring->supply); } } /* Return the number of bytes that are available for consuming * (but don't give more than enough to get to cross over set mark) */ int ring_full_count(Ring *ring) { if ((ring->mark == 0) || (ring->mark == ring->consume)) { if (ring_full(ring)) { return ring->size; /* nothing consumed, but full */ } else { return ring_subtract(ring, ring->supply, ring->consume); } } else { return ring_subtract(ring, ring->mark, ring->consume); } } /* * Return the number of CONSECUTIVE bytes available for consuming. * However, don't return more than enough to cross over set mark. */ int ring_full_consecutive(Ring *ring) { if ((ring->mark == 0) || (ring->mark == ring->consume)) { if ((ring->supply < ring->consume) || ring_full(ring)) { return ring_subtract(ring, ring->top, ring->consume); } else { return ring_subtract(ring, ring->supply, ring->consume); } } else { if (ring->mark < ring->consume) { return ring_subtract(ring, ring->top, ring->consume); } else { /* Else, distance to mark */ return ring_subtract(ring, ring->mark, ring->consume); } } } /* * Move data into the "supply" portion of of the ring buffer. */ void ring_supply_data(Ring *ring, unsigned char *buffer, int count) { int i; while (count) { i = MIN(count, ring_empty_consecutive(ring)); memcpy(ring->supply, buffer, i); ring_supplied(ring, i); count -= i; buffer += i; } } #ifdef ENCRYPTION void ring_encrypt(Ring *ring, void (*encryptor)(unsigned char *, int)) { unsigned char *s, *c; if (ring_empty(ring) || ring->clearto == ring->supply) return; if (!(c = ring->clearto)) c = ring->consume; s = ring->supply; if (s <= c) { (*encryptor)(c, ring->top - c); (*encryptor)(ring->bottom, s - ring->bottom); } else (*encryptor)(c, s - c); ring->clearto = ring->supply; } void ring_clearto(ring) Ring *ring; { if (!ring_empty(ring)) ring->clearto = ring->supply; else ring->clearto = 0; } #endif /* ENCRYPTION */