1 /* @(#)tcp.h 1.11 88/08/19 SMI; from UCB 7.2 10/28/86 */ 2 3 /* 4 * Copyright (c) 1982, 1986 Regents of the University of California. 5 * All rights reserved. The Berkeley software License Agreement 6 * specifies the terms and conditions for redistribution. 7 */ 8 9 #ifndef _netinet_tcp_h 10 #define _netinet_tcp_h 11 12 typedef u_long tcp_seq; 13 /* 14 * TCP header. 15 * Per RFC 793, September, 1981. 16 */ 17 struct tcphdr { 18 u_short th_sport; /* source port */ 19 u_short th_dport; /* destination port */ 20 tcp_seq th_seq; /* sequence number */ 21 tcp_seq th_ack; /* acknowledgement number */ 22 #if defined(vax) || defined(i386) 23 u_char th_x2:4, /* (unused) */ 24 th_off:4; /* data offset */ 25 #endif 26 #if defined(mc68000) || defined(sparc) 27 u_char th_off:4, /* data offset */ 28 th_x2:4; /* (unused) */ 29 #endif 30 u_char th_flags; 31 #define TH_FIN 0x01 32 #define TH_SYN 0x02 33 #define TH_RST 0x04 34 #define TH_PUSH 0x08 35 #define TH_ACK 0x10 36 #define TH_URG 0x20 37 u_short th_win; /* window */ 38 u_short th_sum; /* checksum */ 39 u_short th_urp; /* urgent pointer */ 40 }; 41 42 #define TCPOPT_EOL 0 43 #define TCPOPT_NOP 1 44 #define TCPOPT_MAXSEG 2 45 46 /* 47 * Default maximum segment size for TCP. 48 * With an IP MSS of 576, this is 536, 49 * but 512 is probably more convenient. 50 */ 51 #ifdef lint 52 #define TCP_MSS 536 53 #else 54 #define TCP_MSS MIN(512, IP_MSS - sizeof (struct tcpiphdr)) 55 #endif 56 #endif /*!_netinet_tcp_h*/ 57