1*23187Smckusick /* 2*23187Smckusick * Copyright (c) 1982 Regents of the University of California. 3*23187Smckusick * All rights reserved. The Berkeley software License Agreement 4*23187Smckusick * specifies the terms and conditions for redistribution. 5*23187Smckusick * 6*23187Smckusick * @(#)tcp.h 6.3 (Berkeley) 06/08/85 7*23187Smckusick */ 84573Swnj 95085Swnj typedef u_long tcp_seq; 104573Swnj /* 114899Swnj * TCP header. 124924Swnj * Per RFC 793, September, 1981. 134573Swnj */ 144899Swnj struct tcphdr { 154899Swnj u_short th_sport; /* source port */ 164899Swnj u_short th_dport; /* destination port */ 175085Swnj tcp_seq th_seq; /* sequence number */ 185085Swnj tcp_seq th_ack; /* acknowledgement number */ 199992Ssam #ifdef vax 209992Ssam u_char th_x2:4, /* (unused) */ 214899Swnj th_off:4; /* data offset */ 229992Ssam #endif 234575Swnj u_char th_flags; 245065Swnj #define TH_FIN 0x01 255065Swnj #define TH_SYN 0x02 265065Swnj #define TH_RST 0x04 275065Swnj #define TH_PUSH 0x08 285065Swnj #define TH_ACK 0x10 295065Swnj #define TH_URG 0x20 304899Swnj u_short th_win; /* window */ 314899Swnj u_short th_sum; /* checksum */ 324899Swnj u_short th_urp; /* urgent pointer */ 334499Swnj }; 345440Swnj 355440Swnj #define TCPOPT_EOL 0 365440Swnj #define TCPOPT_NOP 1 375440Swnj #define TCPOPT_MAXSEG 2 3817316Skarels 3917316Skarels /* 4017316Skarels * Default maximum segment size for TCP. 4117316Skarels * With an IP MSS of 576, this is 536, 4217316Skarels * but 512 is probably more convenient. 4317316Skarels */ 4417316Skarels #define TCP_MSS MIN(512, IP_MSS - sizeof (struct tcpiphdr)) 45