tcp.h revision 212653
1/*- 2 * Copyright (c) 1982, 1986, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 4. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 * @(#)tcp.h 8.1 (Berkeley) 6/10/93 30 * $FreeBSD: head/sys/netinet/tcp.h 212653 2010-09-15 10:39:30Z andre $ 31 */ 32 33#ifndef _NETINET_TCP_H_ 34#define _NETINET_TCP_H_ 35 36#include <sys/cdefs.h> 37 38#if __BSD_VISIBLE 39 40typedef u_int32_t tcp_seq; 41 42#define tcp6_seq tcp_seq /* for KAME src sync over BSD*'s */ 43#define tcp6hdr tcphdr /* for KAME src sync over BSD*'s */ 44 45/* 46 * TCP header. 47 * Per RFC 793, September, 1981. 48 */ 49struct tcphdr { 50 u_short th_sport; /* source port */ 51 u_short th_dport; /* destination port */ 52 tcp_seq th_seq; /* sequence number */ 53 tcp_seq th_ack; /* acknowledgement number */ 54#if BYTE_ORDER == LITTLE_ENDIAN 55 u_char th_x2:4, /* (unused) */ 56 th_off:4; /* data offset */ 57#endif 58#if BYTE_ORDER == BIG_ENDIAN 59 u_char th_off:4, /* data offset */ 60 th_x2:4; /* (unused) */ 61#endif 62 u_char th_flags; 63#define TH_FIN 0x01 64#define TH_SYN 0x02 65#define TH_RST 0x04 66#define TH_PUSH 0x08 67#define TH_ACK 0x10 68#define TH_URG 0x20 69#define TH_ECE 0x40 70#define TH_CWR 0x80 71#define TH_FLAGS (TH_FIN|TH_SYN|TH_RST|TH_PUSH|TH_ACK|TH_URG|TH_ECE|TH_CWR) 72#define PRINT_TH_FLAGS "\20\1FIN\2SYN\3RST\4PUSH\5ACK\6URG\7ECE\10CWR" 73 74 u_short th_win; /* window */ 75 u_short th_sum; /* checksum */ 76 u_short th_urp; /* urgent pointer */ 77}; 78 79#define TCPOPT_EOL 0 80#define TCPOLEN_EOL 1 81#define TCPOPT_PAD 0 /* padding after EOL */ 82#define TCPOLEN_PAD 1 83#define TCPOPT_NOP 1 84#define TCPOLEN_NOP 1 85#define TCPOPT_MAXSEG 2 86#define TCPOLEN_MAXSEG 4 87#define TCPOPT_WINDOW 3 88#define TCPOLEN_WINDOW 3 89#define TCPOPT_SACK_PERMITTED 4 90#define TCPOLEN_SACK_PERMITTED 2 91#define TCPOPT_SACK 5 92#define TCPOLEN_SACKHDR 2 93#define TCPOLEN_SACK 8 /* 2*sizeof(tcp_seq) */ 94#define TCPOPT_TIMESTAMP 8 95#define TCPOLEN_TIMESTAMP 10 96#define TCPOLEN_TSTAMP_APPA (TCPOLEN_TIMESTAMP+2) /* appendix A */ 97#define TCPOPT_SIGNATURE 19 /* Keyed MD5: RFC 2385 */ 98#define TCPOLEN_SIGNATURE 18 99 100/* Miscellaneous constants */ 101#define MAX_SACK_BLKS 6 /* Max # SACK blocks stored at receiver side */ 102#define TCP_MAX_SACK 4 /* MAX # SACKs sent in any segment */ 103 104 105/* 106 * The default maximum segment size (MSS) to be used for new TCP connections 107 * when path MTU discovery is not enabled. 108 * 109 * RFC879 derives the default MSS from the largest datagram size hosts are 110 * minimally required to handle directly or through IP reassembly minus the 111 * size of the IP and TCP header. With IPv6 the minimum MTU is specified 112 * in RFC2460. 113 * 114 * For IPv4 the MSS is 576 - sizeof(struct tcpiphdr) 115 * For IPv6 the MSS is IPV6_MMTU - sizeof(struct ip6_hdr) - sizeof(struct tcphdr) 116 * 117 * We use explicit numerical definition here to avoid header pollution. 118 */ 119#define TCP_MSS 536 120#define TCP6_MSS 1220 121 122/* 123 * Limit the lowest MSS we accept from path MTU discovery and the TCP SYN MSS 124 * option. Allowing too low values of MSS can consume significant amounts of 125 * resources and be used as a form of a resource exhaustion attack. 126 * Connections requesting lower MSS values will be rounded up to this value 127 * and the IP_DF flag is cleared to allow fragmentation along the path. 128 * 129 * See tcp_subr.c tcp_minmss SYSCTL declaration for more comments. Setting 130 * it to "0" disables the minmss check. 131 * 132 * The default value is fine for the smallest official link MTU (256 bytes, 133 * AX.25 packet radio) in the Internet. However it is very unlikely to come 134 * across such low MTU interfaces these days (anno domini 2003). 135 */ 136#define TCP_MINMSS 216 137 138#define TCP_MAXWIN 65535 /* largest value for (unscaled) window */ 139#define TTCP_CLIENT_SND_WND 4096 /* dflt send window for T/TCP client */ 140 141#define TCP_MAX_WINSHIFT 14 /* maximum window shift */ 142 143#define TCP_MAXBURST 4 /* maximum segments in a burst */ 144 145#define TCP_MAXHLEN (0xf<<2) /* max length of header in bytes */ 146#define TCP_MAXOLEN (TCP_MAXHLEN - sizeof(struct tcphdr)) 147 /* max space left for options */ 148#endif /* __BSD_VISIBLE */ 149 150/* 151 * User-settable options (used with setsockopt). 152 */ 153#define TCP_NODELAY 0x01 /* don't delay send to coalesce packets */ 154#if __BSD_VISIBLE 155#define TCP_MAXSEG 0x02 /* set maximum segment size */ 156#define TCP_NOPUSH 0x04 /* don't push last block of write */ 157#define TCP_NOOPT 0x08 /* don't use TCP options */ 158#define TCP_MD5SIG 0x10 /* use MD5 digests (RFC2385) */ 159#define TCP_INFO 0x20 /* retrieve tcp_info structure */ 160#define TCP_CONGESTION 0x40 /* get/set congestion control algorithm */ 161 162#define TCP_CA_NAME_MAX 16 /* max congestion control name length */ 163 164#define TCPI_OPT_TIMESTAMPS 0x01 165#define TCPI_OPT_SACK 0x02 166#define TCPI_OPT_WSCALE 0x04 167#define TCPI_OPT_ECN 0x08 168#define TCPI_OPT_TOE 0x10 169 170/* 171 * The TCP_INFO socket option comes from the Linux 2.6 TCP API, and permits 172 * the caller to query certain information about the state of a TCP 173 * connection. We provide an overlapping set of fields with the Linux 174 * implementation, but since this is a fixed size structure, room has been 175 * left for growth. In order to maximize potential future compatibility with 176 * the Linux API, the same variable names and order have been adopted, and 177 * padding left to make room for omitted fields in case they are added later. 178 * 179 * XXX: This is currently an unstable ABI/API, in that it is expected to 180 * change. 181 */ 182struct tcp_info { 183 u_int8_t tcpi_state; /* TCP FSM state. */ 184 u_int8_t __tcpi_ca_state; 185 u_int8_t __tcpi_retransmits; 186 u_int8_t __tcpi_probes; 187 u_int8_t __tcpi_backoff; 188 u_int8_t tcpi_options; /* Options enabled on conn. */ 189 u_int8_t tcpi_snd_wscale:4, /* RFC1323 send shift value. */ 190 tcpi_rcv_wscale:4; /* RFC1323 recv shift value. */ 191 192 u_int32_t tcpi_rto; /* Retransmission timeout (usec). */ 193 u_int32_t __tcpi_ato; 194 u_int32_t tcpi_snd_mss; /* Max segment size for send. */ 195 u_int32_t tcpi_rcv_mss; /* Max segment size for receive. */ 196 197 u_int32_t __tcpi_unacked; 198 u_int32_t __tcpi_sacked; 199 u_int32_t __tcpi_lost; 200 u_int32_t __tcpi_retrans; 201 u_int32_t __tcpi_fackets; 202 203 /* Times; measurements in usecs. */ 204 u_int32_t __tcpi_last_data_sent; 205 u_int32_t __tcpi_last_ack_sent; /* Also unimpl. on Linux? */ 206 u_int32_t tcpi_last_data_recv; /* Time since last recv data. */ 207 u_int32_t __tcpi_last_ack_recv; 208 209 /* Metrics; variable units. */ 210 u_int32_t __tcpi_pmtu; 211 u_int32_t __tcpi_rcv_ssthresh; 212 u_int32_t tcpi_rtt; /* Smoothed RTT in usecs. */ 213 u_int32_t tcpi_rttvar; /* RTT variance in usecs. */ 214 u_int32_t tcpi_snd_ssthresh; /* Slow start threshold. */ 215 u_int32_t tcpi_snd_cwnd; /* Send congestion window. */ 216 u_int32_t __tcpi_advmss; 217 u_int32_t __tcpi_reordering; 218 219 u_int32_t __tcpi_rcv_rtt; 220 u_int32_t tcpi_rcv_space; /* Advertised recv window. */ 221 222 /* FreeBSD extensions to tcp_info. */ 223 u_int32_t tcpi_snd_wnd; /* Advertised send window. */ 224 u_int32_t tcpi_snd_bwnd; /* Bandwidth send window. */ 225 u_int32_t tcpi_snd_nxt; /* Next egress seqno */ 226 u_int32_t tcpi_rcv_nxt; /* Next ingress seqno */ 227 u_int32_t tcpi_toe_tid; /* HWTID for TOE endpoints */ 228 229 /* Padding to grow without breaking ABI. */ 230 u_int32_t __tcpi_pad[29]; /* Padding. */ 231}; 232#endif 233 234#endif /* !_NETINET_TCP_H_ */ 235