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 * $FreeBSD$ 31 */ 32 33 #ifndef _NETINET_TCP_H_ 34 #define _NETINET_TCP_H_ 35 36 #include <sys/cdefs.h> 37 #include <sys/types.h> 38 39 #if __BSD_VISIBLE 40 41 typedef u_int32_t tcp_seq; 42 43 #define tcp6_seq tcp_seq /* for KAME src sync over BSD*'s */ 44 #define tcp6hdr tcphdr /* for KAME src sync over BSD*'s */ 45 46 /* 47 * TCP header. 48 * Per RFC 793, September, 1981. 49 */ 50 struct tcphdr { 51 u_short th_sport; /* source port */ 52 u_short th_dport; /* destination port */ 53 tcp_seq th_seq; /* sequence number */ 54 tcp_seq th_ack; /* acknowledgement number */ 55 #if BYTE_ORDER == LITTLE_ENDIAN 56 u_char th_x2:4, /* (unused) */ 57 th_off:4; /* data offset */ 58 #endif 59 #if BYTE_ORDER == BIG_ENDIAN 60 u_char th_off:4, /* data offset */ 61 th_x2:4; /* (unused) */ 62 #endif 63 u_char th_flags; 64 #define TH_FIN 0x01 65 #define TH_SYN 0x02 66 #define TH_RST 0x04 67 #define TH_PUSH 0x08 68 #define TH_ACK 0x10 69 #define TH_URG 0x20 70 #define TH_ECE 0x40 71 #define TH_CWR 0x80 72 #define TH_FLAGS (TH_FIN|TH_SYN|TH_RST|TH_PUSH|TH_ACK|TH_URG|TH_ECE|TH_CWR) 73 #define PRINT_TH_FLAGS "\20\1FIN\2SYN\3RST\4PUSH\5ACK\6URG\7ECE\10CWR" 74 75 u_short th_win; /* window */ 76 u_short th_sum; /* checksum */ 77 u_short th_urp; /* urgent pointer */ 78 }; 79 80 #define TCPOPT_EOL 0 81 #define TCPOLEN_EOL 1 82 #define TCPOPT_PAD 0 /* padding after EOL */ 83 #define TCPOLEN_PAD 1 84 #define TCPOPT_NOP 1 85 #define TCPOLEN_NOP 1 86 #define TCPOPT_MAXSEG 2 87 #define TCPOLEN_MAXSEG 4 88 #define TCPOPT_WINDOW 3 89 #define TCPOLEN_WINDOW 3 90 #define TCPOPT_SACK_PERMITTED 4 91 #define TCPOLEN_SACK_PERMITTED 2 92 #define TCPOPT_SACK 5 93 #define TCPOLEN_SACKHDR 2 94 #define TCPOLEN_SACK 8 /* 2*sizeof(tcp_seq) */ 95 #define TCPOPT_TIMESTAMP 8 96 #define TCPOLEN_TIMESTAMP 10 97 #define TCPOLEN_TSTAMP_APPA (TCPOLEN_TIMESTAMP+2) /* appendix A */ 98 #define TCPOPT_SIGNATURE 19 /* Keyed MD5: RFC 2385 */ 99 #define TCPOLEN_SIGNATURE 18 100 101 /* Miscellaneous constants */ 102 #define MAX_SACK_BLKS 6 /* Max # SACK blocks stored at receiver side */ 103 #define TCP_MAX_SACK 4 /* MAX # SACKs sent in any segment */ 104 105 106 /* 107 * The default maximum segment size (MSS) to be used for new TCP connections 108 * when path MTU discovery is not enabled. 109 * 110 * RFC879 derives the default MSS from the largest datagram size hosts are 111 * minimally required to handle directly or through IP reassembly minus the 112 * size of the IP and TCP header. With IPv6 the minimum MTU is specified 113 * in RFC2460. 114 * 115 * For IPv4 the MSS is 576 - sizeof(struct tcpiphdr) 116 * For IPv6 the MSS is IPV6_MMTU - sizeof(struct ip6_hdr) - sizeof(struct tcphdr) 117 * 118 * We use explicit numerical definition here to avoid header pollution. 119 */ 120 #define TCP_MSS 536 121 #define TCP6_MSS 1220 122 123 /* 124 * Limit the lowest MSS we accept for path MTU discovery and the TCP SYN MSS 125 * option. Allowing low values of MSS can consume significant resources and 126 * be used to mount a resource exhaustion attack. 127 * Connections requesting lower MSS values will be rounded up to this value 128 * and the IP_DF flag will be cleared to allow fragmentation along the path. 129 * 130 * See tcp_subr.c tcp_minmss SYSCTL declaration for more comments. Setting 131 * it to "0" disables the minmss check. 132 * 133 * The default value is fine for TCP across the Internet's smallest official 134 * link MTU (256 bytes for AX.25 packet radio). However, a connection is very 135 * unlikely to come across such low MTU interfaces these days (anno domini 2003). 136 */ 137 #define TCP_MINMSS 216 138 139 #define TCP_MAXWIN 65535 /* largest value for (unscaled) window */ 140 #define TTCP_CLIENT_SND_WND 4096 /* dflt send window for T/TCP client */ 141 142 #define TCP_MAX_WINSHIFT 14 /* maximum window shift */ 143 144 #define TCP_MAXBURST 4 /* maximum segments in a burst */ 145 146 #define TCP_MAXHLEN (0xf<<2) /* max length of header in bytes */ 147 #define TCP_MAXOLEN (TCP_MAXHLEN - sizeof(struct tcphdr)) 148 /* max space left for options */ 149 #endif /* __BSD_VISIBLE */ 150 151 /* 152 * User-settable options (used with setsockopt). These are discrete 153 * values and are not masked together. Some values appear to be 154 * bitmasks for historical reasons. 155 */ 156 #define TCP_NODELAY 1 /* don't delay send to coalesce packets */ 157 #if __BSD_VISIBLE 158 #define TCP_MAXSEG 2 /* set maximum segment size */ 159 #define TCP_NOPUSH 4 /* don't push last block of write */ 160 #define TCP_NOOPT 8 /* don't use TCP options */ 161 #define TCP_MD5SIG 16 /* use MD5 digests (RFC2385) */ 162 #define TCP_INFO 32 /* retrieve tcp_info structure */ 163 #define TCP_CONGESTION 64 /* get/set congestion control algorithm */ 164 #define TCP_KEEPINIT 128 /* N, time to establish connection */ 165 #define TCP_KEEPIDLE 256 /* L,N,X start keeplives after this period */ 166 #define TCP_KEEPINTVL 512 /* L,N interval between keepalives */ 167 #define TCP_KEEPCNT 1024 /* L,N number of keepalives before close */ 168 #define TCP_PCAP_OUT 2048 /* number of output packets to keep */ 169 #define TCP_PCAP_IN 4096 /* number of input packets to keep */ 170 171 /* Start of reserved space for third-party user-settable options. */ 172 #define TCP_VENDOR SO_VENDOR 173 174 #define TCP_CA_NAME_MAX 16 /* max congestion control name length */ 175 176 #define TCPI_OPT_TIMESTAMPS 0x01 177 #define TCPI_OPT_SACK 0x02 178 #define TCPI_OPT_WSCALE 0x04 179 #define TCPI_OPT_ECN 0x08 180 #define TCPI_OPT_TOE 0x10 181 182 /* 183 * The TCP_INFO socket option comes from the Linux 2.6 TCP API, and permits 184 * the caller to query certain information about the state of a TCP 185 * connection. We provide an overlapping set of fields with the Linux 186 * implementation, but since this is a fixed size structure, room has been 187 * left for growth. In order to maximize potential future compatibility with 188 * the Linux API, the same variable names and order have been adopted, and 189 * padding left to make room for omitted fields in case they are added later. 190 * 191 * XXX: This is currently an unstable ABI/API, in that it is expected to 192 * change. 193 */ 194 struct tcp_info { 195 u_int8_t tcpi_state; /* TCP FSM state. */ 196 u_int8_t __tcpi_ca_state; 197 u_int8_t __tcpi_retransmits; 198 u_int8_t __tcpi_probes; 199 u_int8_t __tcpi_backoff; 200 u_int8_t tcpi_options; /* Options enabled on conn. */ 201 u_int8_t tcpi_snd_wscale:4, /* RFC1323 send shift value. */ 202 tcpi_rcv_wscale:4; /* RFC1323 recv shift value. */ 203 204 u_int32_t tcpi_rto; /* Retransmission timeout (usec). */ 205 u_int32_t __tcpi_ato; 206 u_int32_t tcpi_snd_mss; /* Max segment size for send. */ 207 u_int32_t tcpi_rcv_mss; /* Max segment size for receive. */ 208 209 u_int32_t __tcpi_unacked; 210 u_int32_t __tcpi_sacked; 211 u_int32_t __tcpi_lost; 212 u_int32_t __tcpi_retrans; 213 u_int32_t __tcpi_fackets; 214 215 /* Times; measurements in usecs. */ 216 u_int32_t __tcpi_last_data_sent; 217 u_int32_t __tcpi_last_ack_sent; /* Also unimpl. on Linux? */ 218 u_int32_t tcpi_last_data_recv; /* Time since last recv data. */ 219 u_int32_t __tcpi_last_ack_recv; 220 221 /* Metrics; variable units. */ 222 u_int32_t __tcpi_pmtu; 223 u_int32_t __tcpi_rcv_ssthresh; 224 u_int32_t tcpi_rtt; /* Smoothed RTT in usecs. */ 225 u_int32_t tcpi_rttvar; /* RTT variance in usecs. */ 226 u_int32_t tcpi_snd_ssthresh; /* Slow start threshold. */ 227 u_int32_t tcpi_snd_cwnd; /* Send congestion window. */ 228 u_int32_t __tcpi_advmss; 229 u_int32_t __tcpi_reordering; 230 231 u_int32_t __tcpi_rcv_rtt; 232 u_int32_t tcpi_rcv_space; /* Advertised recv window. */ 233 234 /* FreeBSD extensions to tcp_info. */ 235 u_int32_t tcpi_snd_wnd; /* Advertised send window. */ 236 u_int32_t tcpi_snd_bwnd; /* No longer used. */ 237 u_int32_t tcpi_snd_nxt; /* Next egress seqno */ 238 u_int32_t tcpi_rcv_nxt; /* Next ingress seqno */ 239 u_int32_t tcpi_toe_tid; /* HWTID for TOE endpoints */ 240 u_int32_t tcpi_snd_rexmitpack; /* Retransmitted packets */ 241 u_int32_t tcpi_rcv_ooopack; /* Out-of-order packets */ 242 u_int32_t tcpi_snd_zerowin; /* Zero-sized windows sent */ 243 244 /* Padding to grow without breaking ABI. */ 245 u_int32_t __tcpi_pad[26]; /* Padding. */ 246 }; 247 #endif 248 249 #endif /* !_NETINET_TCP_H_ */ 250