1 /* 2 * Copyright (c) 1982, 1986, 1993, 1995 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 * @(#)tcp_seq.h 8.3 (Berkeley) 6/21/95 34 * $FreeBSD$ 35 */ 36 37 #ifndef _NETINET_TCP_SEQ_H_ 38 #define _NETINET_TCP_SEQ_H_ 39 /* 40 * TCP sequence numbers are 32 bit integers operated 41 * on with modular arithmetic. These macros can be 42 * used to compare such integers. 43 */ 44 #define SEQ_LT(a,b) ((int)((a)-(b)) < 0) 45 #define SEQ_LEQ(a,b) ((int)((a)-(b)) <= 0) 46 #define SEQ_GT(a,b) ((int)((a)-(b)) > 0) 47 #define SEQ_GEQ(a,b) ((int)((a)-(b)) >= 0) 48 49 /* for modulo comparisons of timestamps */ 50 #define TSTMP_LT(a,b) ((int)((a)-(b)) < 0) 51 #define TSTMP_GEQ(a,b) ((int)((a)-(b)) >= 0) 52 53 /* 54 * TCP connection counts are 32 bit integers operated 55 * on with modular arithmetic. These macros can be 56 * used to compare such integers. 57 */ 58 #define CC_LT(a,b) ((int)((a)-(b)) < 0) 59 #define CC_LEQ(a,b) ((int)((a)-(b)) <= 0) 60 #define CC_GT(a,b) ((int)((a)-(b)) > 0) 61 #define CC_GEQ(a,b) ((int)((a)-(b)) >= 0) 62 63 /* Macro to increment a CC: skip 0 which has a special meaning */ 64 #define CC_INC(c) (++(c) == 0 ? ++(c) : (c)) 65 66 /* 67 * Macros to initialize tcp sequence numbers for 68 * send and receive from initial send and receive 69 * sequence numbers. 70 */ 71 #define tcp_rcvseqinit(tp) \ 72 (tp)->rcv_adv = (tp)->rcv_nxt = (tp)->irs + 1 73 74 #define tcp_sendseqinit(tp) \ 75 (tp)->snd_una = (tp)->snd_nxt = (tp)->snd_max = (tp)->snd_up = \ 76 (tp)->iss 77 78 #define TCP_PAWS_IDLE (24 * 24 * 60 * 60 * hz) 79 /* timestamp wrap-around time */ 80 81 #ifdef _KERNEL 82 extern tcp_cc tcp_ccgen; /* global connection count */ 83 84 /* 85 * Increment for tcp_iss each second. 86 * This is designed to increment at the standard 250 KB/s, 87 * but with a random component averaging 128 KB. 88 * We also increment tcp_iss by a quarter of this amount 89 * each time we use the value for a new connection. 90 * If defined, the tcp_random18() macro should produce a 91 * number in the range [0-0x3ffff] that is hard to predict. 92 */ 93 #ifndef tcp_random18 94 #define tcp_random18() ((random() >> 14) & 0x3ffff) 95 #endif 96 #define TCP_ISSINCR (122*1024 + tcp_random18()) 97 98 extern tcp_seq tcp_iss; /* tcp initial send seq # */ 99 #else 100 #define TCP_ISSINCR (250*1024) /* increment for tcp_iss each second */ 101 #endif /* _KERNEL */ 102 #endif /* _NETINET_TCP_SEQ_H_ */ 103