1*17316Skarels /* tcp.h 6.2 84/11/01 */ 24573Swnj 35085Swnj typedef u_long tcp_seq; 44573Swnj /* 54899Swnj * TCP header. 64924Swnj * Per RFC 793, September, 1981. 74573Swnj */ 84899Swnj struct tcphdr { 94899Swnj u_short th_sport; /* source port */ 104899Swnj u_short th_dport; /* destination port */ 115085Swnj tcp_seq th_seq; /* sequence number */ 125085Swnj tcp_seq th_ack; /* acknowledgement number */ 139992Ssam #ifdef vax 149992Ssam u_char th_x2:4, /* (unused) */ 154899Swnj th_off:4; /* data offset */ 169992Ssam #endif 174575Swnj u_char th_flags; 185065Swnj #define TH_FIN 0x01 195065Swnj #define TH_SYN 0x02 205065Swnj #define TH_RST 0x04 215065Swnj #define TH_PUSH 0x08 225065Swnj #define TH_ACK 0x10 235065Swnj #define TH_URG 0x20 244899Swnj u_short th_win; /* window */ 254899Swnj u_short th_sum; /* checksum */ 264899Swnj u_short th_urp; /* urgent pointer */ 274499Swnj }; 285440Swnj 295440Swnj #define TCPOPT_EOL 0 305440Swnj #define TCPOPT_NOP 1 315440Swnj #define TCPOPT_MAXSEG 2 32*17316Skarels 33*17316Skarels /* 34*17316Skarels * Default maximum segment size for TCP. 35*17316Skarels * With an IP MSS of 576, this is 536, 36*17316Skarels * but 512 is probably more convenient. 37*17316Skarels */ 38*17316Skarels #define TCP_MSS MIN(512, IP_MSS - sizeof (struct tcpiphdr)) 39