1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1982, 1986, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the University nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 * 31 * @(#)tcp.h 8.1 (Berkeley) 6/10/93 32 * $FreeBSD$ 33 */ 34 35 #ifndef _NETINET_TCP_H_ 36 #define _NETINET_TCP_H_ 37 38 #include <sys/cdefs.h> 39 #include <sys/types.h> 40 41 #if __BSD_VISIBLE 42 43 typedef u_int32_t tcp_seq; 44 45 #define tcp6_seq tcp_seq /* for KAME src sync over BSD*'s */ 46 #define tcp6hdr tcphdr /* for KAME src sync over BSD*'s */ 47 48 /* 49 * TCP header. 50 * Per RFC 793, September, 1981. 51 */ 52 struct tcphdr { 53 u_short th_sport; /* source port */ 54 u_short th_dport; /* destination port */ 55 tcp_seq th_seq; /* sequence number */ 56 tcp_seq th_ack; /* acknowledgement number */ 57 #if BYTE_ORDER == LITTLE_ENDIAN 58 u_char th_x2:4, /* (unused) */ 59 th_off:4; /* data offset */ 60 #endif 61 #if BYTE_ORDER == BIG_ENDIAN 62 u_char th_off:4, /* data offset */ 63 th_x2:4; /* (unused) */ 64 #endif 65 u_char th_flags; 66 #define TH_FIN 0x01 67 #define TH_SYN 0x02 68 #define TH_RST 0x04 69 #define TH_PUSH 0x08 70 #define TH_ACK 0x10 71 #define TH_URG 0x20 72 #define TH_ECE 0x40 73 #define TH_CWR 0x80 74 #define TH_FLAGS (TH_FIN|TH_SYN|TH_RST|TH_PUSH|TH_ACK|TH_URG|TH_ECE|TH_CWR) 75 #define PRINT_TH_FLAGS "\20\1FIN\2SYN\3RST\4PUSH\5ACK\6URG\7ECE\10CWR" 76 77 u_short th_win; /* window */ 78 u_short th_sum; /* checksum */ 79 u_short th_urp; /* urgent pointer */ 80 }; 81 82 #define TCPOPT_EOL 0 83 #define TCPOLEN_EOL 1 84 #define TCPOPT_PAD 0 /* padding after EOL */ 85 #define TCPOLEN_PAD 1 86 #define TCPOPT_NOP 1 87 #define TCPOLEN_NOP 1 88 #define TCPOPT_MAXSEG 2 89 #define TCPOLEN_MAXSEG 4 90 #define TCPOPT_WINDOW 3 91 #define TCPOLEN_WINDOW 3 92 #define TCPOPT_SACK_PERMITTED 4 93 #define TCPOLEN_SACK_PERMITTED 2 94 #define TCPOPT_SACK 5 95 #define TCPOLEN_SACKHDR 2 96 #define TCPOLEN_SACK 8 /* 2*sizeof(tcp_seq) */ 97 #define TCPOPT_TIMESTAMP 8 98 #define TCPOLEN_TIMESTAMP 10 99 #define TCPOLEN_TSTAMP_APPA (TCPOLEN_TIMESTAMP+2) /* appendix A */ 100 #define TCPOPT_SIGNATURE 19 /* Keyed MD5: RFC 2385 */ 101 #define TCPOLEN_SIGNATURE 18 102 #define TCPOPT_FAST_OPEN 34 103 #define TCPOLEN_FAST_OPEN_EMPTY 2 104 105 /* Miscellaneous constants */ 106 #define MAX_SACK_BLKS 6 /* Max # SACK blocks stored at receiver side */ 107 #define TCP_MAX_SACK 4 /* MAX # SACKs sent in any segment */ 108 109 110 /* 111 * The default maximum segment size (MSS) to be used for new TCP connections 112 * when path MTU discovery is not enabled. 113 * 114 * RFC879 derives the default MSS from the largest datagram size hosts are 115 * minimally required to handle directly or through IP reassembly minus the 116 * size of the IP and TCP header. With IPv6 the minimum MTU is specified 117 * in RFC2460. 118 * 119 * For IPv4 the MSS is 576 - sizeof(struct tcpiphdr) 120 * For IPv6 the MSS is IPV6_MMTU - sizeof(struct ip6_hdr) - sizeof(struct tcphdr) 121 * 122 * We use explicit numerical definition here to avoid header pollution. 123 */ 124 #define TCP_MSS 536 125 #define TCP6_MSS 1220 126 127 /* 128 * Limit the lowest MSS we accept for path MTU discovery and the TCP SYN MSS 129 * option. Allowing low values of MSS can consume significant resources and 130 * be used to mount a resource exhaustion attack. 131 * Connections requesting lower MSS values will be rounded up to this value 132 * and the IP_DF flag will be cleared to allow fragmentation along the path. 133 * 134 * See tcp_subr.c tcp_minmss SYSCTL declaration for more comments. Setting 135 * it to "0" disables the minmss check. 136 * 137 * The default value is fine for TCP across the Internet's smallest official 138 * link MTU (256 bytes for AX.25 packet radio). However, a connection is very 139 * unlikely to come across such low MTU interfaces these days (anno domini 2003). 140 */ 141 #define TCP_MINMSS 216 142 143 #define TCP_MAXWIN 65535 /* largest value for (unscaled) window */ 144 #define TTCP_CLIENT_SND_WND 4096 /* dflt send window for T/TCP client */ 145 146 #define TCP_MAX_WINSHIFT 14 /* maximum window shift */ 147 148 #define TCP_MAXBURST 4 /* maximum segments in a burst */ 149 150 #define TCP_MAXHLEN (0xf<<2) /* max length of header in bytes */ 151 #define TCP_MAXOLEN (TCP_MAXHLEN - sizeof(struct tcphdr)) 152 /* max space left for options */ 153 154 #define TCP_FASTOPEN_MIN_COOKIE_LEN 4 /* Per RFC7413 */ 155 #define TCP_FASTOPEN_MAX_COOKIE_LEN 16 /* Per RFC7413 */ 156 #define TCP_FASTOPEN_PSK_LEN 16 /* Same as TCP_FASTOPEN_KEY_LEN */ 157 #endif /* __BSD_VISIBLE */ 158 159 /* 160 * User-settable options (used with setsockopt). These are discrete 161 * values and are not masked together. Some values appear to be 162 * bitmasks for historical reasons. 163 */ 164 #define TCP_NODELAY 1 /* don't delay send to coalesce packets */ 165 #if __BSD_VISIBLE 166 #define TCP_MAXSEG 2 /* set maximum segment size */ 167 #define TCP_NOPUSH 4 /* don't push last block of write */ 168 #define TCP_NOOPT 8 /* don't use TCP options */ 169 #define TCP_MD5SIG 16 /* use MD5 digests (RFC2385) */ 170 #define TCP_INFO 32 /* retrieve tcp_info structure */ 171 #define TCP_LOG 34 /* configure event logging for connection */ 172 #define TCP_LOGBUF 35 /* retrieve event log for connection */ 173 #define TCP_LOGID 36 /* configure log ID to correlate connections */ 174 #define TCP_LOGDUMP 37 /* dump connection log events to device */ 175 #define TCP_LOGDUMPID 38 /* dump events from connections with same ID to 176 device */ 177 #define TCP_CONGESTION 64 /* get/set congestion control algorithm */ 178 #define TCP_CCALGOOPT 65 /* get/set cc algorithm specific options */ 179 #define TCP_KEEPINIT 128 /* N, time to establish connection */ 180 #define TCP_KEEPIDLE 256 /* L,N,X start keeplives after this period */ 181 #define TCP_KEEPINTVL 512 /* L,N interval between keepalives */ 182 #define TCP_KEEPCNT 1024 /* L,N number of keepalives before close */ 183 #define TCP_FASTOPEN 1025 /* enable TFO / was created via TFO */ 184 #define TCP_PCAP_OUT 2048 /* number of output packets to keep */ 185 #define TCP_PCAP_IN 4096 /* number of input packets to keep */ 186 #define TCP_FUNCTION_BLK 8192 /* Set the tcp function pointers to the specified stack */ 187 /* Start of reserved space for third-party user-settable options. */ 188 #define TCP_VENDOR SO_VENDOR 189 190 #define TCP_CA_NAME_MAX 16 /* max congestion control name length */ 191 192 #define TCPI_OPT_TIMESTAMPS 0x01 193 #define TCPI_OPT_SACK 0x02 194 #define TCPI_OPT_WSCALE 0x04 195 #define TCPI_OPT_ECN 0x08 196 #define TCPI_OPT_TOE 0x10 197 198 /* Maximum length of log ID. */ 199 #define TCP_LOG_ID_LEN 64 200 201 /* 202 * The TCP_INFO socket option comes from the Linux 2.6 TCP API, and permits 203 * the caller to query certain information about the state of a TCP 204 * connection. We provide an overlapping set of fields with the Linux 205 * implementation, but since this is a fixed size structure, room has been 206 * left for growth. In order to maximize potential future compatibility with 207 * the Linux API, the same variable names and order have been adopted, and 208 * padding left to make room for omitted fields in case they are added later. 209 * 210 * XXX: This is currently an unstable ABI/API, in that it is expected to 211 * change. 212 */ 213 struct tcp_info { 214 u_int8_t tcpi_state; /* TCP FSM state. */ 215 u_int8_t __tcpi_ca_state; 216 u_int8_t __tcpi_retransmits; 217 u_int8_t __tcpi_probes; 218 u_int8_t __tcpi_backoff; 219 u_int8_t tcpi_options; /* Options enabled on conn. */ 220 u_int8_t tcpi_snd_wscale:4, /* RFC1323 send shift value. */ 221 tcpi_rcv_wscale:4; /* RFC1323 recv shift value. */ 222 223 u_int32_t tcpi_rto; /* Retransmission timeout (usec). */ 224 u_int32_t __tcpi_ato; 225 u_int32_t tcpi_snd_mss; /* Max segment size for send. */ 226 u_int32_t tcpi_rcv_mss; /* Max segment size for receive. */ 227 228 u_int32_t __tcpi_unacked; 229 u_int32_t __tcpi_sacked; 230 u_int32_t __tcpi_lost; 231 u_int32_t __tcpi_retrans; 232 u_int32_t __tcpi_fackets; 233 234 /* Times; measurements in usecs. */ 235 u_int32_t __tcpi_last_data_sent; 236 u_int32_t __tcpi_last_ack_sent; /* Also unimpl. on Linux? */ 237 u_int32_t tcpi_last_data_recv; /* Time since last recv data. */ 238 u_int32_t __tcpi_last_ack_recv; 239 240 /* Metrics; variable units. */ 241 u_int32_t __tcpi_pmtu; 242 u_int32_t __tcpi_rcv_ssthresh; 243 u_int32_t tcpi_rtt; /* Smoothed RTT in usecs. */ 244 u_int32_t tcpi_rttvar; /* RTT variance in usecs. */ 245 u_int32_t tcpi_snd_ssthresh; /* Slow start threshold. */ 246 u_int32_t tcpi_snd_cwnd; /* Send congestion window. */ 247 u_int32_t __tcpi_advmss; 248 u_int32_t __tcpi_reordering; 249 250 u_int32_t __tcpi_rcv_rtt; 251 u_int32_t tcpi_rcv_space; /* Advertised recv window. */ 252 253 /* FreeBSD extensions to tcp_info. */ 254 u_int32_t tcpi_snd_wnd; /* Advertised send window. */ 255 u_int32_t tcpi_snd_bwnd; /* No longer used. */ 256 u_int32_t tcpi_snd_nxt; /* Next egress seqno */ 257 u_int32_t tcpi_rcv_nxt; /* Next ingress seqno */ 258 u_int32_t tcpi_toe_tid; /* HWTID for TOE endpoints */ 259 u_int32_t tcpi_snd_rexmitpack; /* Retransmitted packets */ 260 u_int32_t tcpi_rcv_ooopack; /* Out-of-order packets */ 261 u_int32_t tcpi_snd_zerowin; /* Zero-sized windows sent */ 262 263 /* Padding to grow without breaking ABI. */ 264 u_int32_t __tcpi_pad[26]; /* Padding. */ 265 }; 266 267 /* 268 * If this structure is provided when setting the TCP_FASTOPEN socket 269 * option, and the enable member is non-zero, a subsequent connect will use 270 * pre-shared key (PSK) mode using the provided key. 271 */ 272 struct tcp_fastopen { 273 int enable; 274 uint8_t psk[TCP_FASTOPEN_PSK_LEN]; 275 }; 276 #endif 277 #define TCP_FUNCTION_NAME_LEN_MAX 32 278 279 struct tcp_function_set { 280 char function_set_name[TCP_FUNCTION_NAME_LEN_MAX]; 281 uint32_t pcbcnt; 282 }; 283 284 #endif /* !_NETINET_TCP_H_ */ 285