sys/netinet/tcp.h

   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 #define TCPOPT_FAST_OPEN        34
 101 #define    TCPOLEN_FAST_OPEN_EMPTY      2
 102 #define    TCPOLEN_FAST_OPEN_MIN        6
 103 #define    TCPOLEN_FAST_OPEN_MAX        18
 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 #endif /* __BSD_VISIBLE */
 154
 155 /*
 156  * User-settable options (used with setsockopt).  These are discrete
 157  * values and are not masked together.  Some values appear to be
 158  * bitmasks for historical reasons.
 159  */
 160 #define TCP_NODELAY     1       /* don't delay send to coalesce packets */
 161 #if __BSD_VISIBLE
 162 #define TCP_MAXSEG      2       /* set maximum segment size */
 163 #define TCP_NOPUSH      4       /* don't push last block of write */
 164 #define TCP_NOOPT       8       /* don't use TCP options */
 165 #define TCP_MD5SIG      16      /* use MD5 digests (RFC2385) */
 166 #define TCP_INFO        32      /* retrieve tcp_info structure */
 167 #define TCP_CONGESTION  64      /* get/set congestion control algorithm */
 168 #define TCP_CCALGOOPT   65      /* get/set cc algorithm specific options */
 169 #define TCP_KEEPINIT    128     /* N, time to establish connection */
 170 #define TCP_KEEPIDLE    256     /* L,N,X start keeplives after this period */
 171 #define TCP_KEEPINTVL   512     /* L,N interval between keepalives */
 172 #define TCP_KEEPCNT     1024    /* L,N number of keepalives before close */
 173 #define TCP_FASTOPEN    1025    /* enable TFO / was created via TFO */
 174 #define TCP_PCAP_OUT    2048    /* number of output packets to keep */
 175 #define TCP_PCAP_IN     4096    /* number of input packets to keep */
 176 #define TCP_FUNCTION_BLK 8192   /* Set the tcp function pointers to the specified stack */
 177 /* Start of reserved space for third-party user-settable options. */
 178 #define TCP_VENDOR      SO_VENDOR
 179
 180 #define TCP_CA_NAME_MAX 16      /* max congestion control name length */
 181
 182 #define TCPI_OPT_TIMESTAMPS     0x01
 183 #define TCPI_OPT_SACK           0x02
 184 #define TCPI_OPT_WSCALE         0x04
 185 #define TCPI_OPT_ECN            0x08
 186 #define TCPI_OPT_TOE            0x10
 187
 188 /*
 189  * The TCP_INFO socket option comes from the Linux 2.6 TCP API, and permits
 190  * the caller to query certain information about the state of a TCP
 191  * connection.  We provide an overlapping set of fields with the Linux
 192  * implementation, but since this is a fixed size structure, room has been
 193  * left for growth.  In order to maximize potential future compatibility with
 194  * the Linux API, the same variable names and order have been adopted, and
 195  * padding left to make room for omitted fields in case they are added later.
 196  *
 197  * XXX: This is currently an unstable ABI/API, in that it is expected to
 198  * change.
 199  */
 200 struct tcp_info {
 201         u_int8_t        tcpi_state;             /* TCP FSM state. */
 202         u_int8_t        __tcpi_ca_state;
 203         u_int8_t        __tcpi_retransmits;
 204         u_int8_t        __tcpi_probes;
 205         u_int8_t        __tcpi_backoff;
 206         u_int8_t        tcpi_options;           /* Options enabled on conn. */
 207         u_int8_t        tcpi_snd_wscale:4,      /* RFC1323 send shift value. */
 208                         tcpi_rcv_wscale:4;      /* RFC1323 recv shift value. */
 209
 210         u_int32_t       tcpi_rto;               /* Retransmission timeout (usec). */
 211         u_int32_t       __tcpi_ato;
 212         u_int32_t       tcpi_snd_mss;           /* Max segment size for send. */
 213         u_int32_t       tcpi_rcv_mss;           /* Max segment size for receive. */
 214
 215         u_int32_t       __tcpi_unacked;
 216         u_int32_t       __tcpi_sacked;
 217         u_int32_t       __tcpi_lost;
 218         u_int32_t       __tcpi_retrans;
 219         u_int32_t       __tcpi_fackets;
 220
 221         /* Times; measurements in usecs. */
 222         u_int32_t       __tcpi_last_data_sent;
 223         u_int32_t       __tcpi_last_ack_sent;   /* Also unimpl. on Linux? */
 224         u_int32_t       tcpi_last_data_recv;    /* Time since last recv data. */
 225         u_int32_t       __tcpi_last_ack_recv;
 226
 227         /* Metrics; variable units. */
 228         u_int32_t       __tcpi_pmtu;
 229         u_int32_t       __tcpi_rcv_ssthresh;
 230         u_int32_t       tcpi_rtt;               /* Smoothed RTT in usecs. */
 231         u_int32_t       tcpi_rttvar;            /* RTT variance in usecs. */
 232         u_int32_t       tcpi_snd_ssthresh;      /* Slow start threshold. */
 233         u_int32_t       tcpi_snd_cwnd;          /* Send congestion window. */
 234         u_int32_t       __tcpi_advmss;
 235         u_int32_t       __tcpi_reordering;
 236
 237         u_int32_t       __tcpi_rcv_rtt;
 238         u_int32_t       tcpi_rcv_space;         /* Advertised recv window. */
 239
 240         /* FreeBSD extensions to tcp_info. */
 241         u_int32_t       tcpi_snd_wnd;           /* Advertised send window. */
 242         u_int32_t       tcpi_snd_bwnd;          /* No longer used. */
 243         u_int32_t       tcpi_snd_nxt;           /* Next egress seqno */
 244         u_int32_t       tcpi_rcv_nxt;           /* Next ingress seqno */
 245         u_int32_t       tcpi_toe_tid;           /* HWTID for TOE endpoints */
 246         u_int32_t       tcpi_snd_rexmitpack;    /* Retransmitted packets */
 247         u_int32_t       tcpi_rcv_ooopack;       /* Out-of-order packets */
 248         u_int32_t       tcpi_snd_zerowin;       /* Zero-sized windows sent */
 249
 250         /* Padding to grow without breaking ABI. */
 251         u_int32_t       __tcpi_pad[26];         /* Padding. */
 252 };
 253 #endif
 254 #define TCP_FUNCTION_NAME_LEN_MAX 32
 255
 256 struct tcp_function_set {
 257         char function_set_name[TCP_FUNCTION_NAME_LEN_MAX];
 258         uint32_t pcbcnt;
 259 };
 260
 261 #endif /* !_NETINET_TCP_H_ */