FreeBSD/Linux Kernel Cross Reference
sys/netinet/tcp.h

     /*-
      * SPDX-License-Identifier: BSD-3-Clause
      *
      * Copyright (c) 1982, 1986, 1993
      *      The Regents of the University of California.  All rights reserved.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     *      @(#)tcp.h       8.1 (Berkeley) 6/10/93
     * $FreeBSD$
     */
    
    #ifndef _NETINET_TCP_H_
    #define _NETINET_TCP_H_
    
    #include <sys/cdefs.h>
    #include <sys/types.h>
    
    #if __BSD_VISIBLE
    
    typedef u_int32_t tcp_seq;
    
    #define tcp6_seq        tcp_seq /* for KAME src sync over BSD*'s */
    #define tcp6hdr         tcphdr  /* for KAME src sync over BSD*'s */
    
    /*
     * TCP header.
     * Per RFC 793, September, 1981.
     */
    struct tcphdr {
            u_short th_sport;               /* source port */
            u_short th_dport;               /* destination port */
            tcp_seq th_seq;                 /* sequence number */
            tcp_seq th_ack;                 /* acknowledgement number */
    #if BYTE_ORDER == LITTLE_ENDIAN
            u_char  th_x2:4,                /* upper 4 (reserved) flags */
                    th_off:4;               /* data offset */
    #endif
    #if BYTE_ORDER == BIG_ENDIAN
            u_char  th_off:4,               /* data offset */
                    th_x2:4;                /* upper 4 (reserved) flags */
    #endif
            u_char  th_flags;
    #define TH_FIN  0x01
    #define TH_SYN  0x02
    #define TH_RST  0x04
    #define TH_PUSH 0x08
    #define TH_ACK  0x10
    #define TH_URG  0x20
    #define TH_ECE  0x40
    #define TH_CWR  0x80
    #define TH_AE   0x100                   /* maps into th_x2 */
    #define TH_RES3 0x200
    #define TH_RES2 0x400
    #define TH_RES1 0x800
    #define TH_FLAGS        (TH_FIN|TH_SYN|TH_RST|TH_PUSH|TH_ACK|TH_URG|TH_ECE|TH_CWR)
    #define PRINT_TH_FLAGS  "\2\1FIN\2SYN\3RST\4PUSH\5ACK\6URG\7ECE\10CWR\11AE"
    
            u_short th_win;                 /* window */
            u_short th_sum;                 /* checksum */
            u_short th_urp;                 /* urgent pointer */
    };
    
    #define PADTCPOLEN(len)         ((((len) / 4) + !!((len) % 4)) * 4)
    
    #define TCPOPT_EOL              0
    #define    TCPOLEN_EOL                  1
    #define TCPOPT_PAD              0               /* padding after EOL */
    #define    TCPOLEN_PAD                  1
    #define TCPOPT_NOP              1
    #define    TCPOLEN_NOP                  1
    #define TCPOPT_MAXSEG           2
    #define    TCPOLEN_MAXSEG               4
    #define TCPOPT_WINDOW           3
    #define    TCPOLEN_WINDOW               3
    #define TCPOPT_SACK_PERMITTED   4
    #define    TCPOLEN_SACK_PERMITTED       2
   #define TCPOPT_SACK             5
   #define    TCPOLEN_SACKHDR              2
   #define    TCPOLEN_SACK                 8       /* 2*sizeof(tcp_seq) */
   #define TCPOPT_TIMESTAMP        8
   #define    TCPOLEN_TIMESTAMP            10
   #define    TCPOLEN_TSTAMP_APPA          (TCPOLEN_TIMESTAMP+2) /* appendix A */
   #define TCPOPT_SIGNATURE        19              /* Keyed MD5: RFC 2385 */
   #define    TCPOLEN_SIGNATURE            18
   #define TCPOPT_FAST_OPEN        34
   #define    TCPOLEN_FAST_OPEN_EMPTY      2
   
   #define MAX_TCPOPTLEN           40      /* Absolute maximum TCP options len */
   
   /* Miscellaneous constants */
   #define MAX_SACK_BLKS   6       /* Max # SACK blocks stored at receiver side */
   #define TCP_MAX_SACK    4       /* MAX # SACKs sent in any segment */
   
   /*
    * The default maximum segment size (MSS) to be used for new TCP connections
    * when path MTU discovery is not enabled.
    *
    * RFC879 derives the default MSS from the largest datagram size hosts are
    * minimally required to handle directly or through IP reassembly minus the
    * size of the IP and TCP header.  With IPv6 the minimum MTU is specified
    * in RFC2460.
    *
    * For IPv4 the MSS is 576 - sizeof(struct tcpiphdr)
    * For IPv6 the MSS is IPV6_MMTU - sizeof(struct ip6_hdr) - sizeof(struct tcphdr)
    *
    * We use explicit numerical definition here to avoid header pollution.
    */
   #define TCP_MSS         536
   #define TCP6_MSS        1220
   
   /*
    * Limit the lowest MSS we accept for path MTU discovery and the TCP SYN MSS
    * option.  Allowing low values of MSS can consume significant resources and
    * be used to mount a resource exhaustion attack.
    * Connections requesting lower MSS values will be rounded up to this value
    * and the IP_DF flag will be cleared to allow fragmentation along the path.
    *
    * See tcp_subr.c tcp_minmss SYSCTL declaration for more comments.  Setting
    * it to "" disables the minmss check.
    *
    * The default value is fine for TCP across the Internet's smallest official
    * link MTU (256 bytes for AX.25 packet radio).  However, a connection is very
    * unlikely to come across such low MTU interfaces these days (anno domini 2003).
    */
   #define TCP_MINMSS 216
   
   #define TCP_MAXWIN      65535   /* largest value for (unscaled) window */
   #define TTCP_CLIENT_SND_WND     4096    /* dflt send window for T/TCP client */
   
   #define TCP_MAX_WINSHIFT        14      /* maximum window shift */
   
   #define TCP_MAXBURST            4       /* maximum segments in a burst */
   
   #define TCP_MAXHLEN     (0xf<<2)        /* max length of header in bytes */
   #define TCP_MAXOLEN     (TCP_MAXHLEN - sizeof(struct tcphdr))
                                           /* max space left for options */
   
   #define TCP_FASTOPEN_MIN_COOKIE_LEN     4       /* Per RFC7413 */
   #define TCP_FASTOPEN_MAX_COOKIE_LEN     16      /* Per RFC7413 */
   #define TCP_FASTOPEN_PSK_LEN            16      /* Same as TCP_FASTOPEN_KEY_LEN */
   #endif /* __BSD_VISIBLE */
   
   /*
    * User-settable options (used with setsockopt).  These are discrete
    * values and are not masked together.  Some values appear to be
    * bitmasks for historical reasons.
    */
   #define TCP_NODELAY     1       /* don't delay send to coalesce packets */
   #if __BSD_VISIBLE
   #define TCP_MAXSEG      2       /* set maximum segment size */
   #define TCP_NOPUSH      4       /* don't push last block of write */
   #define TCP_NOOPT       8       /* don't use TCP options */
   #define TCP_MD5SIG      16      /* use MD5 digests (RFC2385) */
   #define TCP_INFO        32      /* retrieve tcp_info structure */
   #define TCP_STATS       33      /* retrieve stats blob structure */
   #define TCP_LOG         34      /* configure event logging for connection */
   #define TCP_LOGBUF      35      /* retrieve event log for connection */
   #define TCP_LOGID       36      /* configure log ID to correlate connections */
   #define TCP_LOGDUMP     37      /* dump connection log events to device */
   #define TCP_LOGDUMPID   38      /* dump events from connections with same ID to
                                      device */
   #define TCP_TXTLS_ENABLE 39     /* TLS framing and encryption for transmit */
   #define TCP_TXTLS_MODE  40      /* Transmit TLS mode */
   #define TCP_RXTLS_ENABLE 41     /* TLS framing and encryption for receive */
   #define TCP_RXTLS_MODE  42      /* Receive TLS mode */
   #define TCP_IWND_NB     43      /* Override initial window (units: bytes) */
   #define TCP_IWND_NSEG   44      /* Override initial window (units: MSS segs) */
   #define TCP_LOGID_CNT   46      /* get number of connections with the same ID */
   #define TCP_LOG_TAG     47      /* configure tag for grouping logs */
   #define TCP_USER_LOG    48      /* userspace log event */
   #define TCP_CONGESTION  64      /* get/set congestion control algorithm */
   #define TCP_CCALGOOPT   65      /* get/set cc algorithm specific options */
   #define TCP_MAXUNACKTIME 68     /* maximum time without making progress (sec) */
   #define TCP_MAXPEAKRATE 69      /* maximum peak rate allowed (kbps) */
   #define TCP_IDLE_REDUCE 70      /* Reduce cwnd on idle input */
   #define TCP_REMOTE_UDP_ENCAPS_PORT 71   /* Enable TCP over UDP tunneling via the specified port */
   #define TCP_DELACK      72      /* socket option for delayed ack */
   #define TCP_FIN_IS_RST 73       /* A fin from the peer is treated has a RST */
   #define TCP_LOG_LIMIT  74       /* Limit to number of records in tcp-log */
   #define TCP_SHARED_CWND_ALLOWED 75      /* Use of a shared cwnd is allowed */
   #define TCP_PROC_ACCOUNTING 76  /* Do accounting on tcp cpu usage and counts */
   #define TCP_USE_CMP_ACKS 77     /* The transport can handle the Compressed mbuf acks */
   #define TCP_PERF_INFO   78      /* retrieve accounting counters */
   #define TCP_LRD         79      /* toggle Lost Retransmission Detection for A/B testing */
   #define TCP_KEEPINIT    128     /* N, time to establish connection */
   #define TCP_KEEPIDLE    256     /* L,N,X start keeplives after this period */
   #define TCP_KEEPINTVL   512     /* L,N interval between keepalives */
   #define TCP_KEEPCNT     1024    /* L,N number of keepalives before close */
   #define TCP_FASTOPEN    1025    /* enable TFO / was created via TFO */
   #define TCP_PCAP_OUT    2048    /* number of output packets to keep */
   #define TCP_PCAP_IN     4096    /* number of input packets to keep */
   #define TCP_FUNCTION_BLK 8192   /* Set the tcp function pointers to the specified stack */
   #define TCP_FUNCTION_ALIAS 8193 /* Get the current tcp function pointer name alias */
   /* Options for Rack and BBR */
   #define TCP_REUSPORT_LB_NUMA   1026     /* set listen socket numa domain */
   #define TCP_RACK_MBUF_QUEUE   1050 /* Do we allow mbuf queuing if supported */
   #define TCP_RACK_PROP         1051 /* RACK proportional rate reduction (bool) */
   #define TCP_RACK_TLP_REDUCE   1052 /* RACK TLP cwnd reduction (bool) */
   #define TCP_RACK_PACE_REDUCE  1053 /* RACK Pacingv reduction factor (divisor) */
   #define TCP_RACK_PACE_MAX_SEG 1054 /* Max TSO size we will send  */
   #define TCP_RACK_PACE_ALWAYS  1055 /* Use the always pace method */
   #define TCP_RACK_PROP_RATE    1056 /* The proportional reduction rate */
   #define TCP_RACK_PRR_SENDALOT 1057 /* Allow PRR to send more than one seg */
   #define TCP_RACK_MIN_TO       1058 /* Minimum time between rack t-o's in ms */
   #define TCP_RACK_EARLY_RECOV  1059 /* Should recovery happen early (bool) */
   #define TCP_RACK_EARLY_SEG    1060 /* If early recovery max segments */
   #define TCP_RACK_REORD_THRESH 1061 /* RACK reorder threshold (shift amount) */
   #define TCP_RACK_REORD_FADE   1062 /* Does reordering fade after ms time */
   #define TCP_RACK_TLP_THRESH   1063 /* RACK TLP theshold i.e. srtt+(srtt/N) */
   #define TCP_RACK_PKT_DELAY    1064 /* RACK added ms i.e. rack-rtt + reord + N */
   #define TCP_RACK_TLP_INC_VAR  1065 /* Does TLP include rtt variance in t-o */
   #define TCP_BBR_IWINTSO       1067 /* Initial TSO window for BBRs first sends */
   #define TCP_BBR_RECFORCE      1068 /* Enter recovery force out a segment disregard pacer no longer valid */
   #define TCP_BBR_STARTUP_PG    1069 /* Startup pacing gain */
   #define TCP_BBR_DRAIN_PG      1070 /* Drain pacing gain */
   #define TCP_BBR_RWND_IS_APP   1071 /* Rwnd limited is considered app limited */
   #define TCP_BBR_PROBE_RTT_INT 1072 /* How long in useconds between probe-rtt */
   #define TCP_BBR_ONE_RETRAN    1073 /* Is only one segment allowed out during retran */
   #define TCP_BBR_STARTUP_LOSS_EXIT 1074  /* Do we exit a loss during startup if not 20% incr */
   #define TCP_BBR_USE_LOWGAIN   1075 /* lower the gain in PROBE_BW enable */
   #define TCP_BBR_LOWGAIN_THRESH 1076 /* Unused after 2.3 morphs to TSLIMITS >= 2.3 */
   #define TCP_BBR_TSLIMITS 1076      /* Do we use experimental Timestamp limiting for our algo */
   #define TCP_BBR_LOWGAIN_HALF  1077 /* Unused after 2.3 */
   #define TCP_BBR_PACE_OH        1077 /* Reused in 4.2 for pacing overhead setting */
   #define TCP_BBR_LOWGAIN_FD    1078 /* Unused after 2.3 */
   #define TCP_BBR_HOLD_TARGET 1078        /* For 4.3 on */
   #define TCP_BBR_USEDEL_RATE   1079 /* Enable use of delivery rate for loss recovery */
   #define TCP_BBR_MIN_RTO       1080 /* Min RTO in milliseconds */
   #define TCP_BBR_MAX_RTO       1081 /* Max RTO in milliseconds */
   #define TCP_BBR_REC_OVER_HPTS 1082 /* Recovery override htps settings 0/1/3 */
   #define TCP_BBR_UNLIMITED     1083 /* Not used before 2.3 and morphs to algorithm >= 2.3 */
   #define TCP_BBR_ALGORITHM     1083 /* What measurement algo does BBR use netflix=0, google=1 */
   #define TCP_BBR_DRAIN_INC_EXTRA 1084 /* Does the 3/4 drain target include the extra gain */
   #define TCP_BBR_STARTUP_EXIT_EPOCH 1085 /* what epoch gets us out of startup */
   #define TCP_BBR_PACE_PER_SEC   1086
   #define TCP_BBR_PACE_DEL_TAR   1087
   #define TCP_BBR_PACE_SEG_MAX   1088
   #define TCP_BBR_PACE_SEG_MIN   1089
   #define TCP_BBR_PACE_CROSS     1090
   #define TCP_RACK_IDLE_REDUCE_HIGH 1092  /* Reduce the highest cwnd seen to IW on idle */
   #define TCP_RACK_MIN_PACE      1093     /* Do we enforce rack min pace time */
   #define TCP_RACK_MIN_PACE_SEG  1094     /* If so what is the seg threshould */
   #define TCP_RACK_GP_INCREASE   1094     /* After 4.1 its the GP increase in older rack */
   #define TCP_RACK_TLP_USE       1095
   #define TCP_BBR_ACK_COMP_ALG   1096     /* Not used */
   #define TCP_BBR_TMR_PACE_OH    1096     /* Recycled in 4.2 */
   #define TCP_BBR_EXTRA_GAIN     1097
   #define TCP_RACK_DO_DETECTION  1097     /* Recycle of extra gain for rack, attack detection */
   #define TCP_BBR_RACK_RTT_USE   1098     /* what RTT should we use 0, 1, or 2? */
   #define TCP_BBR_RETRAN_WTSO    1099
   #define TCP_DATA_AFTER_CLOSE   1100
   #define TCP_BBR_PROBE_RTT_GAIN 1101
   #define TCP_BBR_PROBE_RTT_LEN  1102
   #define TCP_BBR_SEND_IWND_IN_TSO 1103   /* Do we burst out whole iwin size chunks at start? */
   #define TCP_BBR_USE_RACK_RR      1104   /* Do we use the rack rapid recovery for pacing rxt's */
   #define TCP_BBR_USE_RACK_CHEAT TCP_BBR_USE_RACK_RR /* Compat. */
   #define TCP_BBR_HDWR_PACE      1105     /* Enable/disable hardware pacing */
   #define TCP_BBR_UTTER_MAX_TSO  1106     /* Do we enforce an utter max TSO size */
   #define TCP_BBR_EXTRA_STATE    1107     /* Special exit-persist catch up */
   #define TCP_BBR_FLOOR_MIN_TSO  1108     /* The min tso size */
   #define TCP_BBR_MIN_TOPACEOUT  1109     /* Do we suspend pacing until */
   #define TCP_BBR_TSTMP_RAISES   1110     /* Can a timestamp measurement raise the b/w */
   #define TCP_BBR_POLICER_DETECT 1111     /* Turn on/off google mode policer detection */
   #define TCP_BBR_RACK_INIT_RATE 1112     /* Set an initial pacing rate for when we have no b/w in kbits per sec */
   #define TCP_RACK_RR_CONF        1113 /* Rack rapid recovery configuration control*/
   #define TCP_RACK_CHEAT_NOT_CONF_RATE TCP_RACK_RR_CONF
   #define TCP_RACK_GP_INCREASE_CA   1114  /* GP increase for Congestion Avoidance */
   #define TCP_RACK_GP_INCREASE_SS   1115  /* GP increase for Slow Start */
   #define TCP_RACK_GP_INCREASE_REC  1116  /* GP increase for Recovery */
   #define TCP_RACK_FORCE_MSEG     1117    /* Override to use the user set max-seg value */
   #define TCP_RACK_PACE_RATE_CA  1118 /* Pacing rate for Congestion Avoidance */
   #define TCP_RACK_PACE_RATE_SS  1119 /* Pacing rate for Slow Start */
   #define TCP_RACK_PACE_RATE_REC  1120 /* Pacing rate for Recovery */
   #define TCP_NO_PRR              1122 /* If pacing, don't use prr  */
   #define TCP_RACK_NONRXT_CFG_RATE 1123 /* In recovery does a non-rxt use the cfg rate */
   #define TCP_SHARED_CWND_ENABLE   1124   /* Use a shared cwnd if allowed */
   #define TCP_TIMELY_DYN_ADJ       1125 /* Do we attempt dynamic multipler adjustment with timely. */
   #define TCP_RACK_NO_PUSH_AT_MAX 1126 /* For timely do not push if we are over max rtt */
   #define TCP_RACK_PACE_TO_FILL 1127 /* If we are not in recovery, always pace to fill the cwnd in 1 RTT */
   #define TCP_SHARED_CWND_TIME_LIMIT 1128 /* we should limit to low time values the scwnd life */
   #define TCP_RACK_PROFILE 1129   /* Select a profile that sets multiple options */
   #define TCP_HDWR_RATE_CAP 1130 /* Allow hardware rates to cap pacing rate */
   #define TCP_PACING_RATE_CAP 1131 /* Highest rate allowed in pacing in bytes per second (uint64_t) */
   #define TCP_HDWR_UP_ONLY 1132   /* Allow the pacing rate to climb but not descend (with the exception of fill-cw */
   #define TCP_RACK_ABC_VAL 1133   /* Set a local ABC value different then the system default */
   #define TCP_REC_ABC_VAL 1134    /* Do we use the ABC value for recovery or the override one from sysctl  */
   #define TCP_RACK_MEASURE_CNT 1135 /* How many measurements are required in GP pacing */
   #define TCP_DEFER_OPTIONS 1136 /* Defer options until the proper number of measurements occur, does not defer TCP_RACK_MEASURE_CNT */
   #define TCP_FAST_RSM_HACK 1137 /* Do we do the broken thing where we don't twiddle the TLP bits properly in fast_rsm_output? */
   #define TCP_RACK_PACING_BETA 1138       /* Changing the beta for pacing */
   #define TCP_RACK_PACING_BETA_ECN 1139   /* Changing the beta for ecn with pacing */
   #define TCP_RACK_TIMER_SLOP 1140        /* Set or get the timer slop used */
   #define TCP_RACK_DSACK_OPT 1141         /* How do we setup rack timer DSACK options bit 1/2 */
   #define TCP_RACK_ENABLE_HYSTART 1142    /* Do we allow hystart in the CC modules */
   /* Start of reserved space for third-party user-settable options. */
   #define TCP_VENDOR      SO_VENDOR
   
   #define TCP_CA_NAME_MAX 16      /* max congestion control name length */
   
   #define TCPI_OPT_TIMESTAMPS     0x01
   #define TCPI_OPT_SACK           0x02
   #define TCPI_OPT_WSCALE         0x04
   #define TCPI_OPT_ECN            0x08
   #define TCPI_OPT_TOE            0x10
   #define TCPI_OPT_TFO            0x20
   
   /* Maximum length of log ID. */
   #define TCP_LOG_ID_LEN  64
   
   /*
    * The TCP_INFO socket option comes from the Linux 2.6 TCP API, and permits
    * the caller to query certain information about the state of a TCP
    * connection.  We provide an overlapping set of fields with the Linux
    * implementation, but since this is a fixed size structure, room has been
    * left for growth.  In order to maximize potential future compatibility with
    * the Linux API, the same variable names and order have been adopted, and
    * padding left to make room for omitted fields in case they are added later.
    *
    * XXX: This is currently an unstable ABI/API, in that it is expected to
    * change.
    */
   struct tcp_info {
           u_int8_t        tcpi_state;             /* TCP FSM state. */
           u_int8_t        __tcpi_ca_state;
           u_int8_t        __tcpi_retransmits;
           u_int8_t        __tcpi_probes;
           u_int8_t        __tcpi_backoff;
           u_int8_t        tcpi_options;           /* Options enabled on conn. */
           u_int8_t        tcpi_snd_wscale:4,      /* RFC1323 send shift value. */
                           tcpi_rcv_wscale:4;      /* RFC1323 recv shift value. */
   
           u_int32_t       tcpi_rto;               /* Retransmission timeout (usec). */
           u_int32_t       __tcpi_ato;
           u_int32_t       tcpi_snd_mss;           /* Max segment size for send. */
           u_int32_t       tcpi_rcv_mss;           /* Max segment size for receive. */
   
           u_int32_t       __tcpi_unacked;
           u_int32_t       __tcpi_sacked;
           u_int32_t       __tcpi_lost;
           u_int32_t       __tcpi_retrans;
           u_int32_t       __tcpi_fackets;
   
           /* Times; measurements in usecs. */
           u_int32_t       __tcpi_last_data_sent;
           u_int32_t       __tcpi_last_ack_sent;   /* Also unimpl. on Linux? */
           u_int32_t       tcpi_last_data_recv;    /* Time since last recv data. */
           u_int32_t       __tcpi_last_ack_recv;
   
           /* Metrics; variable units. */
           u_int32_t       __tcpi_pmtu;
           u_int32_t       __tcpi_rcv_ssthresh;
           u_int32_t       tcpi_rtt;               /* Smoothed RTT in usecs. */
           u_int32_t       tcpi_rttvar;            /* RTT variance in usecs. */
           u_int32_t       tcpi_snd_ssthresh;      /* Slow start threshold. */
           u_int32_t       tcpi_snd_cwnd;          /* Send congestion window. */
           u_int32_t       __tcpi_advmss;
           u_int32_t       __tcpi_reordering;
   
           u_int32_t       __tcpi_rcv_rtt;
           u_int32_t       tcpi_rcv_space;         /* Advertised recv window. */
   
           /* FreeBSD extensions to tcp_info. */
           u_int32_t       tcpi_snd_wnd;           /* Advertised send window. */
           u_int32_t       tcpi_snd_bwnd;          /* No longer used. */
           u_int32_t       tcpi_snd_nxt;           /* Next egress seqno */
           u_int32_t       tcpi_rcv_nxt;           /* Next ingress seqno */
           u_int32_t       tcpi_toe_tid;           /* HWTID for TOE endpoints */
           u_int32_t       tcpi_snd_rexmitpack;    /* Retransmitted packets */
           u_int32_t       tcpi_rcv_ooopack;       /* Out-of-order packets */
           u_int32_t       tcpi_snd_zerowin;       /* Zero-sized windows sent */
   
           /* Accurate ECN counters. */
           u_int32_t       tcpi_delivered_ce;
           u_int32_t       tcpi_received_ce;               /* # of CE marks received */
           u_int32_t       __tcpi_delivered_e1_bytes;
           u_int32_t       __tcpi_delivered_e0_bytes;
           u_int32_t       __tcpi_delivered_ce_bytes;
           u_int32_t       __tcpi_received_e1_bytes;
           u_int32_t       __tcpi_received_e0_bytes;
           u_int32_t       __tcpi_received_ce_bytes;
   
           /* Padding to grow without breaking ABI. */
           u_int32_t       __tcpi_pad[19];         /* Padding. */
   };
   
   /*
    * If this structure is provided when setting the TCP_FASTOPEN socket
    * option, and the enable member is non-zero, a subsequent connect will use
    * pre-shared key (PSK) mode using the provided key.
    */
   struct tcp_fastopen {
           int enable;
           uint8_t psk[TCP_FASTOPEN_PSK_LEN];
   };
   #endif
   #define TCP_FUNCTION_NAME_LEN_MAX 32
   
   struct tcp_function_set {
           char function_set_name[TCP_FUNCTION_NAME_LEN_MAX];
           uint32_t pcbcnt;
   };
   
   /* TLS modes for TCP_TXTLS_MODE */
   #define TCP_TLS_MODE_NONE       0
   #define TCP_TLS_MODE_SW         1
   #define TCP_TLS_MODE_IFNET      2
   #define TCP_TLS_MODE_TOE        3
   
   /*
    * TCP Control message types
    */
   #define TLS_SET_RECORD_TYPE     1
   #define TLS_GET_RECORD          2
   
   /*
    * TCP specific variables of interest for tp->t_stats stats(9) accounting.
    */
   #define VOI_TCP_TXPB            0 /* Transmit payload bytes */
   #define VOI_TCP_RETXPB          1 /* Retransmit payload bytes */
   #define VOI_TCP_FRWIN           2 /* Foreign receive window */
   #define VOI_TCP_LCWIN           3 /* Local congesiton window */
   #define VOI_TCP_RTT             4 /* Round trip time */
   #define VOI_TCP_CSIG            5 /* Congestion signal */
   #define VOI_TCP_GPUT            6 /* Goodput */
   #define VOI_TCP_CALCFRWINDIFF   7 /* Congestion avoidance LCWIN - FRWIN */
   #define VOI_TCP_GPUT_ND         8 /* Goodput normalised delta */
   #define VOI_TCP_ACKLEN          9 /* Average ACKed bytes per ACK */
   
   #define TCP_REUSPORT_LB_NUMA_NODOM      (-2) /* remove numa binding */
   #define TCP_REUSPORT_LB_NUMA_CURDOM     (-1) /* bind to current domain */
   
   #endif /* !_NETINET_TCP_H_ */

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