1 /* 2 * Copyright (c) 1982, 1986 Regents of the University of California. 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms are permitted 6 * provided that this notice is preserved and that due credit is given 7 * to the University of California at Berkeley. The name of the University 8 * may not be used to endorse or promote products derived from this 9 * software without specific prior written permission. This software 10 * is provided ``as is'' without express or implied warranty. 11 * 12 * @(#)tcp.h 7.3 (Berkeley) 12/07/87 13 */ 14 15 typedef u_long tcp_seq; 16 /* 17 * TCP header. 18 * Per RFC 793, September, 1981. 19 */ 20 struct tcphdr { 21 u_short th_sport; /* source port */ 22 u_short th_dport; /* destination port */ 23 tcp_seq th_seq; /* sequence number */ 24 tcp_seq th_ack; /* acknowledgement number */ 25 #if ENDIAN == LITTLE 26 u_char th_x2:4, /* (unused) */ 27 th_off:4; /* data offset */ 28 #endif 29 #if ENDIAN == BIG 30 u_char th_off:4, /* data offset */ 31 th_x2:4; /* (unused) */ 32 #endif 33 u_char th_flags; 34 #define TH_FIN 0x01 35 #define TH_SYN 0x02 36 #define TH_RST 0x04 37 #define TH_PUSH 0x08 38 #define TH_ACK 0x10 39 #define TH_URG 0x20 40 u_short th_win; /* window */ 41 u_short th_sum; /* checksum */ 42 u_short th_urp; /* urgent pointer */ 43 }; 44 45 #define TCPOPT_EOL 0 46 #define TCPOPT_NOP 1 47 #define TCPOPT_MAXSEG 2 48 49 /* 50 * Default maximum segment size for TCP. 51 * With an IP MSS of 576, this is 536, 52 * but 512 is probably more convenient. 53 */ 54 #ifdef lint 55 #define TCP_MSS 536 56 #else 57 #define TCP_MSS MIN(512, IP_MSS - sizeof (struct tcpiphdr)) 58 #endif 59 60 /* 61 * User-settable options (used with setsockopt). 62 */ 63 #define TCP_NODELAY 0x01 /* don't delay send to coalesce packets */ 64 #define TCP_MAXSEG 0x02 /* set maximum segment size */ 65