1 /* 2 * Copyright (c) 1982, 1986 Regents of the University of California. 3 * All rights reserved. 4 * 5 * %sccs.include.redist.c% 6 * 7 * @(#)tcp.h 7.7 (Berkeley) 06/28/90 8 */ 9 10 typedef u_long tcp_seq; 11 /* 12 * TCP header. 13 * Per RFC 793, September, 1981. 14 */ 15 struct tcphdr { 16 u_short th_sport; /* source port */ 17 u_short th_dport; /* destination port */ 18 tcp_seq th_seq; /* sequence number */ 19 tcp_seq th_ack; /* acknowledgement number */ 20 #if BYTE_ORDER == LITTLE_ENDIAN 21 u_char th_x2:4, /* (unused) */ 22 th_off:4; /* data offset */ 23 #endif 24 #if BYTE_ORDER == BIG_ENDIAN 25 u_char th_off:4, /* data offset */ 26 th_x2:4; /* (unused) */ 27 #endif 28 u_char th_flags; 29 #define TH_FIN 0x01 30 #define TH_SYN 0x02 31 #define TH_RST 0x04 32 #define TH_PUSH 0x08 33 #define TH_ACK 0x10 34 #define TH_URG 0x20 35 u_short th_win; /* window */ 36 u_short th_sum; /* checksum */ 37 u_short th_urp; /* urgent pointer */ 38 }; 39 40 #define TCPOPT_EOL 0 41 #define TCPOPT_NOP 1 42 #define TCPOPT_MAXSEG 2 43 44 /* 45 * Default maximum segment size for TCP. 46 * With an IP MSS of 576, this is 536, 47 * but 512 is probably more convenient. 48 * This should be defined as MIN(512, IP_MSS - sizeof (struct tcpiphdr)). 49 */ 50 #define TCP_MSS 512 51 52 #define TCP_MAXWIN 65535 /* largest value for window */ 53 54 /* 55 * User-settable options (used with setsockopt). 56 */ 57 #define TCP_NODELAY 0x01 /* don't delay send to coalesce packets */ 58 #define TCP_MAXSEG 0x02 /* set maximum segment size */ 59