xnu-7195.101.1.tar.gz

[apple/xnu.git] / bsd / netinet / tcp_timer.h

diff --git a/bsd/netinet/tcp_timer.h b/bsd/netinet/tcp_timer.h
index 213e87a395f241ca9960ee70324097ff4def978b..8d09d9cb627280dc73c344c41625c7a30b4382ae 100644 (file)
--- a/bsd/netinet/tcp_timer.h
+++ b/bsd/netinet/tcp_timer.h
@@ -1,8 +1,8 @@
 /*
 /*

- * Copyright (c) 2000-2010 Apple Computer, Inc. All rights reserved.
+ * Copyright (c) 2000-2014 Apple Computer, Inc. All rights reserved.

  *
  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
  *
  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@

- * 
+ *

  * This file contains Original Code and/or Modifications of Original Code
  * as defined in and that are subject to the Apple Public Source License
  * Version 2.0 (the 'License'). You may not use this file except in
  * This file contains Original Code and/or Modifications of Original Code
  * as defined in and that are subject to the Apple Public Source License
  * Version 2.0 (the 'License'). You may not use this file except in


@@ -11,10 +11,10 @@
  * unlawful or unlicensed copies of an Apple operating system, or to
  * circumvent, violate, or enable the circumvention or violation of, any
  * terms of an Apple operating system software license agreement.
  * unlawful or unlicensed copies of an Apple operating system, or to
  * circumvent, violate, or enable the circumvention or violation of, any
  * terms of an Apple operating system software license agreement.

- * 
+ *

  * Please obtain a copy of the License at
  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  * Please obtain a copy of the License at
  * http://www.opensource.apple.com/apsl/ and read it before using this file.

- * 
+ *

  * The Original Code and all software distributed under the License are
  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  * The Original Code and all software distributed under the License are
  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,


@@ -22,7 +22,7 @@
  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  * Please see the License for the specific language governing rights and
  * limitations under the License.
  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  * Please see the License for the specific language governing rights and
  * limitations under the License.

- * 
+ *

  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  */
 /*
  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  */
 /*


@@ -65,27 +65,23 @@
 #define _NETINET_TCP_TIMER_H_
 #include <sys/appleapiopts.h>
 
 #define _NETINET_TCP_TIMER_H_
 #include <sys/appleapiopts.h>
 

-#ifdef KERNEL
+#ifdef BSD_KERNEL_PRIVATE

 #include <kern/thread_call.h>
 #include <kern/thread_call.h>

-#endif /* KERNEL */
-
-/*
- * Definitions of the TCP timers.
- */
-#define        TCPT_NTIMERS    5
+#endif /* BSD_KERNEL_PRIVATE */

 
 /* Keep the external definition the same for binary compatibility */
 
 /* Keep the external definition the same for binary compatibility */

-#define TCPT_NTIMERS_EXT       4
-
-#define        TCPT_REXMT      0               /* retransmit */
-#define        TCPT_PERSIST    1               /* retransmit persistence */
-#define        TCPT_KEEP       2               /* keep alive */
-#define        TCPT_2MSL       3               /* 2*msl quiet time timer */
-#define        TCPT_DELACK     4               /* delayed ack timer */
-#define        TCPT_MAX        4
-#define        TCPT_NONE       (TCPT_MAX + 1)  
+#define TCPT_NTIMERS_EXT        4

 
 /*
 
 /*

+ * Definitions of the TCP timers.
+ *
+ * The TCPT_PTO timer is used for probing for a tail loss in a send window.
+ * If this probe gets acknowledged using SACK, it will allow the connection
+ * to enter fast-recovery instead of hitting a retransmit timeout. A probe
+ * timeout will send the last unacknowledged segment to generate more acks
+ * with SACK information which can be used for fast-retransmiting the lost
+ * packets. This will fire in the order of 10ms.
+ *

  * The TCPT_REXMT timer is used to force retransmissions.
  * The TCP has the TCPT_REXMT timer set whenever segments
  * have been sent for which ACKs are expected but not yet
  * The TCPT_REXMT timer is used to force retransmissions.
  * The TCP has the TCPT_REXMT timer set whenever segments
  * have been sent for which ACKs are expected but not yet


@@ -96,9 +92,12 @@
  * we retransmit one unacknowledged segment, and do a backoff
  * on the retransmit timer.
  *
  * we retransmit one unacknowledged segment, and do a backoff
  * on the retransmit timer.
  *

+ * The TCPT_DELACK timer is used for transmitting delayed acknowledgements
+ * if an acknowledgement was delayed in anticipation of a new segment.
+ *

  * The TCPT_PERSIST timer is used to keep window size information
  * flowing even if the window goes shut.  If all previous transmissions
  * The TCPT_PERSIST timer is used to keep window size information
  * flowing even if the window goes shut.  If all previous transmissions

- * have been acknowledged (so that there are no retransmissions in progress),
+ * have been acknowledged(so that there are no retransmissions in progress),

  * and the window is too small to bother sending anything, then we start
  * the TCPT_PERSIST timer.  When it expires, if the window is nonzero,
  * we go to transmit state.  Otherwise, at intervals send a single byte
  * and the window is too small to bother sending anything, then we start
  * the TCPT_PERSIST timer.  When it expires, if the window is nonzero,
  * we go to transmit state.  Otherwise, at intervals send a single byte


@@ -109,166 +108,227 @@
  * a window update from the peer.
  *
  * The TCPT_KEEP timer is used to keep connections alive.  If an
  * a window update from the peer.
  *
  * The TCPT_KEEP timer is used to keep connections alive.  If an

- * connection is idle (no segments received) for TCPTV_KEEP_INIT amount of time,
- * but not yet established, then we drop the connection.  Once the connection
- * is established, if the connection is idle for TCPTV_KEEP_IDLE time
- * (and keepalives have been enabled on the socket), we begin to probe
- * the connection.  We force the peer to send us a segment by sending:
+ * connection is idle (no segments received) for TCPTV_KEEP_INIT amount
+ * of time, but not yet established, then we drop the connection.
+ * Once the connection is established, if the connection is idle for
+ * TCPTV_KEEP_IDLE time (and keepalives have been enabled on the socket),
+ * we begin to probe the connection.  We force the peer to send us a
+ * segment by sending:

  *     <SEQ=SND.UNA-1><ACK=RCV.NXT><CTL=ACK>
  * This segment is (deliberately) outside the window, and should elicit
  * an ack segment in response from the peer.  If, despite the TCPT_KEEP
  *     <SEQ=SND.UNA-1><ACK=RCV.NXT><CTL=ACK>
  * This segment is (deliberately) outside the window, and should elicit
  * an ack segment in response from the peer.  If, despite the TCPT_KEEP

- * initiated segments we cannot elicit a response from a peer in TCPT_MAXIDLE
- * amount of time probing, then we drop the connection.
+ * initiated segments we cannot elicit a response from a peer in
+ * TCPT_MAXIDLE amount of time probing, then we drop the connection.
+ *
+ * The TCPT_2MSL timer is used for keeping the conenction in Time-wait state
+ * before fully closing it so that the connection 4-tuple can be reused.
+ */
+#ifdef BSD_KERNEL_PRIVATE
+
+#define TCPT_PTO        0       /* Probe timeout */
+#define TCPT_DELAYFR    1       /* Delay recovery if there is reordering */
+#define TCPT_REXMT      2       /* retransmit */
+#define TCPT_DELACK     3       /* delayed ack */
+#define TCPT_PERSIST    4       /* retransmit persistence */
+#define TCPT_KEEP       5       /* keep alive */
+#define TCPT_2MSL       6       /* 2*msl quiet time timer */
+#if MPTCP
+#define TCPT_JACK_RXMT  7       /* retransmit timer for join ack */
+#define TCPT_CELLICON   8       /* Timer to check for cell-activity */
+#define TCPT_MAX        8
+#else /* MPTCP */
+#define TCPT_MAX        6
+#endif /* !MPTCP */
+
+#define TCPT_NONE       (TCPT_MAX + 1)
+#define TCPT_NTIMERS    (TCPT_MAX + 1)
+
+/* External definitions */
+#define TCPT_REXMT_EXT          0
+#define TCPT_PERSIST_EXT        1
+#define TCPT_KEEP_EXT           2
+#define TCPT_2MSL_EXT           3
+#define TCPT_DELACK_EXT         4
+
+#else /* !BSD_KERNEL_PRIVATE */
+#define TCPT_REXMT      0               /* retransmit */
+#define TCPT_PERSIST    1               /* retransmit persistence */
+#define TCPT_KEEP       2               /* keep alive */
+#define TCPT_2MSL       3               /* 2*msl quiet time timer */
+#define TCPT_DELACK     4               /* delayed ack timer */
+#if MPTCP
+#define TCPT_JACK_RXMT  5       /* retransmit timer for join ack */
+#define TCPT_MAX        5
+#else /* MPTCP */
+#define TCPT_MAX        4
+#endif /* !MPTCP */
+#define TCPT_NONE       (TCPT_MAX + 1)
+#define TCPT_NTIMERS    (TCPT_MAX + 1)
+
+#endif /* BSD_KERNEL_PRIVATE */
+
+#ifdef BSD_KERNEL_PRIVATE
+/*
+ * Time constants.

  */
  */

+#define TCPTV_MSL       ( 15*TCP_RETRANSHZ)     /* max seg lifetime */
+#define TCPTV_SRTTBASE  0       /* base roundtrip time; if 0, no idea yet */
+#define TCPTV_RTOBASE   (  1*TCP_RETRANSHZ)     /* assumed RTO if no info */
+#define TCPTV_SRTTDFLT  (  1*TCP_RETRANSHZ)     /* assumed RTT if no info */
+#define TCPTV_PERSMIN   (  5*TCP_RETRANSHZ)     /* retransmit persistence */
+#define TCPTV_PERSMAX   ( 60*TCP_RETRANSHZ)     /* maximum persist interval */
+
+extern int tcptv_persmin_val;
+
+#define TCPTV_KEEP_INIT ( 75*TCP_RETRANSHZ)     /* connect keep alive */
+#define TCPTV_KEEP_IDLE (120*60*TCP_RETRANSHZ)  /* time before probing */
+#define TCPTV_KEEPINTVL ( 75*TCP_RETRANSHZ)     /* default probe interval */
+#define TCPTV_KEEPCNT   8                       /* max probes before drop */

 
 

-#ifdef PRIVATE
+#define TCPTV_REXMTMAX  ( 64*TCP_RETRANSHZ )    /* max REXMT value */
+#define TCPTV_REXMTMIN  ( TCP_RETRANSHZ/33 )    /* min REXMT for non-local connections */

 
 /*
 
 /*

- * Time constants.
+ * Window for counting received bytes to see if ack-stretching
+ * can start (default 100 ms)

  */
  */

-#define        TCPTV_MSL       ( 15*TCP_RETRANSHZ)             /* max seg lifetime (hah!) */
-#define        TCPTV_SRTTBASE  0                       /* base roundtrip time;
-                                                  if  0, no idea yet */
-#define        TCPTV_RTOBASE   (  1*TCP_RETRANSHZ)             /* assumed RTO if no info */
-#define        TCPTV_SRTTDFLT  (  1*TCP_RETRANSHZ)             /* assumed RTT if no info */
-
-#define        TCPTV_PERSMIN   (  5*TCP_RETRANSHZ)             /* retransmit persistence */
-#define        TCPTV_PERSMAX   ( 60*TCP_RETRANSHZ)             /* maximum persist interval */
-
-#define        TCPTV_KEEP_INIT ( 75*TCP_RETRANSHZ)             /* initial connect keep alive */
-#define        TCPTV_KEEP_IDLE (120*60*TCP_RETRANSHZ)  /* dflt time before probing */
-#define        TCPTV_KEEPINTVL ( 75*TCP_RETRANSHZ)             /* default probe interval */
-#define        TCPTV_KEEPCNT   8                       /* max probes before drop */
-
-#define        TCPTV_REXMTMAX  ( 64*TCP_RETRANSHZ )    /* max allowable REXMT value */
-#define        TCPTV_REXMTMIN  ( TCP_RETRANSHZ/33 )    /* min REXMT for non-local connections */
-#define TCPTV_UNACKWIN ( TCP_RETRANSHZ/10 )    /* Window for counting rcv bytes to see if 
-                                                  ack-stretching can start (default 100 ms) */
-#define TCPTV_MAXRCVIDLE (TCP_RETRANSHZ/5 )    /* Receiver idle time, avoid ack-stretching after that*/
-#define TCPTV_RCVBUFIDLE (TCP_RETRANSHZ/2)     /* Receiver idle time, for rcv socket buffer resizing */
-
-/* No ack stretching during slow-start, until we see some packets.
- * By the time the receiver gets 512 packets, the senders cwnd 
- * should open by a few hundred packets consdering the 
+#define TCPTV_UNACKWIN  ( TCP_RETRANSHZ/10 )
+
+/* Receiver idle time, avoid ack-stretching after this idle time */
+#define TCPTV_MAXRCVIDLE (TCP_RETRANSHZ/5 )
+
+/*
+ * No ack stretching during slow-start, until we see some packets.
+ * By the time the receiver gets 512 packets, the senders cwnd
+ * should open by a few hundred packets consdering the

  * slow-start progression.
  */
 #define TCP_RCV_SS_PKTCOUNT     512
 
  * slow-start progression.
  */
 #define TCP_RCV_SS_PKTCOUNT     512
 

-#define TCPTV_TWTRUNC  8                       /* RTO factor to truncate TW */
+#define TCPTV_TWTRUNC   8               /* RTO factor to truncate TW */

 
 

-#define        TCP_LINGERTIME  120                     /* linger at most 2 minutes */
+#define TCP_LINGERTIME  120             /* linger at most 2 minutes */

 
 

-#define        TCP_MAXRXTSHIFT 12                      /* maximum retransmits */
+#define TCP_MAXRXTSHIFT 12              /* maximum retransmits */

 
 

-#ifdef TCPTIMERS
+#ifdef  TCPTIMERS

 static char *tcptimers[] =
 static char *tcptimers[] =

-    { "REXMT", "PERSIST", "KEEP", "2MSL" , "DELACK"};
-#endif
+{ "REXMT", "PERSIST", "KEEP", "2MSL", "DELACK"};
+#endif /* TCPTIMERS */

 
 

-#ifdef KERNEL
-
-/* We consider persist, keep and 2msl as slow timers which can be coalesced
- * at a higher granularity (500 ms). Rexmt and delayed ack are considered fast
- * timers which fire in the order of 100ms.
+/*
+ * Persist, keep, 2msl and MPTCP's join-ack timer as slow timers which can
+ * be coalesced at a higher granularity (500 ms).

  *
  *

- * The following conditional is to check if a timer is one of the slow timers. This 
- * is fast and works well for now. If we add more slow timers for any reason, 
- * we may need to change this.
+ * Rexmt and delayed ack timers are considered as fast timers which run
+ * in the order of 100ms.
+ *
+ * Probe timeout is a quick timer which will run in the order of 10ms.

  */
  */

-#define IS_TIMER_SLOW(ind) ((ind & 0x3) != 0)
+#define IS_TIMER_HZ_500MS(i)    ((i) >= TCPT_PERSIST)
+#define IS_TIMER_HZ_100MS(i)    ((i) >= TCPT_REXMT && (i) < TCPT_PERSIST)
+#define IS_TIMER_HZ_10MS(i)     ((i) < TCPT_REXMT)

 
 struct tcptimerlist;
 
 struct tcptimerentry {
 
 struct tcptimerlist;
 
 struct tcptimerentry {

-        LIST_ENTRY(tcptimerentry) le;  /* links for timer list */ 
-        uint32_t timer_start;          /* tcp clock when the timer was started */
-       uint16_t index;                 /* index of lowest timer that needs to run first */
-       uint32_t runtime;               /* deadline at which the first timer has to fire */
+       LIST_ENTRY(tcptimerentry) le;   /* links for timer list */
+       uint32_t timer_start;   /* tcp clock when the timer was started */
+       uint16_t index;         /* index of lowest timer that needs to run first */
+       uint16_t mode;          /* Bit-wise OR of timers that are active */
+       uint32_t runtime;       /* deadline at which the first timer has to fire */

 };
 
 LIST_HEAD(timerlisthead, tcptimerentry);
 
 struct tcptimerlist {
 };
 
 LIST_HEAD(timerlisthead, tcptimerentry);
 
 struct tcptimerlist {

-       struct timerlisthead lhead;     /* head of the list of timer entries */
-       lck_mtx_t *mtx;                 /* lock to protect the list */
-       lck_attr_t *mtx_attr;           /* mutex attributes */
-       lck_grp_t *mtx_grp;             /* mutex group definition */
-       lck_grp_attr_t *mtx_grp_attr;   /* mutex group attributes */
-       uint32_t fast_quantum;          /* minimum time quantum to coalesce fast timers */
-       uint32_t slow_quantum;          /* minimum time quantum to coalesce slow timers */
-       thread_call_t call;             /* call entry */
-       uint32_t runtime;               /* time at which this list is going to run */
-       uint32_t entries;               /* Number of entries on the list */
-       uint32_t maxentries;            /* Max number of entries at any time */
+       struct timerlisthead lhead;     /* head of the list */
+       lck_mtx_t *mtx;         /* lock to protect the list */
+       lck_attr_t *mtx_attr;   /* mutex attributes */
+       lck_grp_t *mtx_grp;     /* mutex group definition */
+       lck_grp_attr_t *mtx_grp_attr;   /* mutex group attributes */
+       thread_call_t call;     /* call entry */
+       uint32_t runtime;       /* time at which this list is going to run */
+       uint32_t schedtime;     /* time at which this list was scheduled */
+       uint32_t entries;       /* Number of entries on the list */
+       uint32_t maxentries;    /* Max number of entries at any time */

 
        /* Set desired mode when timer list running */
 
        /* Set desired mode when timer list running */

-       boolean_t running;              /* Set when timer list is being processed */
-#define TCP_TIMERLIST_FASTMODE 0x1
-#define TCP_TIMERLIST_SLOWMODE 0x2
-       uint32_t mode;                  /* Current mode, fast or slow */
-       uint32_t pref_mode;             /* Preferred mode set by a connection, fast or slow */
-       uint32_t pref_offset;           /* Preferred offset set by a connection */
-       uint32_t idlegen;               /* Number of times the list has been idle in fast mode */
-       struct tcptimerentry *next_te;  /* Store the next timer entry pointer to process */
-
+       boolean_t running;      /* Set when timer list is being processed */
+       boolean_t scheduled;    /* set when the timer is scheduled */
+#define TCP_TIMERLIST_10MS_MODE 0x1
+#define TCP_TIMERLIST_100MS_MODE 0x2
+#define TCP_TIMERLIST_500MS_MODE 0x4
+       uint32_t mode;          /* Current mode of the timer */
+       uint32_t pref_mode;     /* Preferred mode set by a connection */
+       uint32_t pref_offset;   /* Preferred offset set by a connection */
+       uint32_t idleruns;      /* Number of times the list has been idle in fast mode */
+       struct tcptimerentry *next_te;  /* next timer entry pointer to process */
+       u_int16_t probe_if_index; /* Interface index that needs to send probes */

 };
 
 };
 

-#define TCP_FASTMODE_IDLEGEN_MAX 20    /* Approximately 2 seconds */
+/* number of idle runs allowed for TCP timer list in fast or quick modes */
+#define TCP_FASTMODE_IDLERUN_MAX 10

 
 /*
 
 /*

- * Minimum retransmit timeout is set to 30ms. We add a slop of 
- * 200 ms to the retransmit value to account for processing 
- * variance and delayed ack. This extra 200ms will help to avoid 
- * spurious retransmits by taking into consideration the receivers 
- * that wait for delayed ack timer instead of generating an ack 
+ * Minimum retransmit timeout is set to 30ms. We add a slop of
+ * 200 ms to the retransmit value to account for processing
+ * variance and delayed ack. This extra 200ms will help to avoid
+ * spurious retransmits by taking into consideration the receivers
+ * that wait for delayed ack timer instead of generating an ack

  * for every two packets.
  *
  * On a local link, the minimum retransmit timeout is 100ms and
  * variance is set to 0. This will make the sender a little bit more
  * aggressive on local link. When the connection is not established yet,
  * there is no need to add an extra 200ms to retransmit timeout because
  * for every two packets.
  *
  * On a local link, the minimum retransmit timeout is 100ms and
  * variance is set to 0. This will make the sender a little bit more
  * aggressive on local link. When the connection is not established yet,
  * there is no need to add an extra 200ms to retransmit timeout because

- * the initial value is high (1s) and delayed ack is not a problem in 
+ * the initial value is high (1s) and delayed ack is not a problem in

  * that case.
  */
  * that case.
  */

-#define TCPTV_REXMTSLOP ( TCP_RETRANSHZ/5 )    /* rexmt slop allowed (200 ms) */
+#define TCPTV_REXMTSLOP ( TCP_RETRANSHZ/5 )     /* extra 200 ms slop */

 
 /* macro to decide when retransmit slop (described above) should be added */
 
 /* macro to decide when retransmit slop (described above) should be added */

-#define TCP_ADD_REXMTSLOP(tp) (tp->t_state >= TCPS_ESTABLISHED) 
+#define TCP_ADD_REXMTSLOP(tp) (tp->t_state >= TCPS_ESTABLISHED)

 
 

-#define        TCPT_RANGESET(tv, value, tvmin, tvmax, addslop) do { \
+#define TCPT_RANGESET(tv, value, tvmin, tvmax, addslop) do { \

        (tv) = ((addslop) ? tcp_rexmt_slop : 0) + (value); \
        if ((uint32_t)(tv) < (uint32_t)(tvmin)) \
        (tv) = ((addslop) ? tcp_rexmt_slop : 0) + (value); \
        if ((uint32_t)(tv) < (uint32_t)(tvmin)) \

-               (tv) = (tvmin); \
+               (tv) = (tvmin); \

        else if ((uint32_t)(tv) > (uint32_t)(tvmax)) \
        else if ((uint32_t)(tv) > (uint32_t)(tvmax)) \

-               (tv) = (tvmax); \
+               (tv) = (tvmax); \

 } while(0)
 
 } while(0)
 

-#define TCP_KEEPIDLE(tp) \
-       (tp->t_keepidle && (tp->t_inpcb->inp_socket->so_options & SO_KEEPALIVE) ? \
-               tp->t_keepidle : tcp_keepidle)
+#define TCP_CONN_KEEPIDLE(tp) \
+       ((tp)->t_keepidle && \
+       ((tp)->t_inpcb->inp_socket->so_options & SO_KEEPALIVE) ? \
+               (tp)->t_keepidle : (uint32_t)tcp_keepidle)
+#define TCP_CONN_KEEPINIT(tp) \
+       (((tp)->t_keepinit > 0) ? (tp)->t_keepinit : (uint32_t)tcp_keepinit)
+#define TCP_CONN_KEEPCNT(tp) \
+       (((tp)->t_keepcnt > 0) ? (tp)->t_keepcnt : (uint32_t)tcp_keepcnt)
+#define TCP_CONN_KEEPINTVL(tp) \
+       (((tp)->t_keepintvl > 0) ? (tp)->t_keepintvl : (uint32_t)tcp_keepintvl)
+#define TCP_CONN_MAXIDLE(tp) \
+       (TCP_CONN_KEEPCNT(tp) * TCP_CONN_KEEPINTVL(tp))

 
 

-/* Since we did not add rexmt slop for local connections, we should add
- * it to idle timeout. Otherwise local connections will reach idle state
- * quickly
- */

 #define TCP_IDLETIMEOUT(tp) \
        (((TCP_ADD_REXMTSLOP(tp)) ? 0 : tcp_rexmt_slop) + tp->t_rxtcur)
 
 #define TCP_IDLETIMEOUT(tp) \
        (((TCP_ADD_REXMTSLOP(tp)) ? 0 : tcp_rexmt_slop) + tp->t_rxtcur)
 

-extern int tcp_keepinit;               /* time to establish connection */
-extern int tcp_keepidle;               /* time before keepalive probes begin */
-extern int tcp_keepintvl;              /* time between keepalive probes */
-extern int tcp_maxidle;                        /* time to drop after starting probes */
-extern int tcp_delack;                 /* delayed ack timer */
+TAILQ_HEAD(tcptailq, tcpcb);
+
+extern int tcp_keepinit;        /* time to establish connection */
+extern int tcp_keepidle;        /* time before keepalive probes begin */
+extern int tcp_keepintvl;       /* time between keepalive probes */
+extern int tcp_keepcnt;         /* number of keepalives */
+extern int tcp_delack;          /* delayed ack timer */

 extern int tcp_maxpersistidle;
 extern int tcp_msl;
 extern int tcp_maxpersistidle;
 extern int tcp_msl;

-extern int tcp_ttl;                    /* time to live for TCP segs */
+extern int tcp_ttl;             /* time to live for TCP segs */

 extern int tcp_backoff[];
 extern int tcp_rexmt_slop;
 extern int tcp_backoff[];
 extern int tcp_rexmt_slop;

-extern u_int32_t tcp_max_persist_timeout;      /* Maximum persistence for Zero Window Probes */
+extern u_int32_t tcp_max_persist_timeout;       /* Maximum persistence for Zero Window Probes */

 
 #define OFFSET_FROM_START(tp, off) ((tcp_now + (off)) - (tp)->tentry.timer_start)
 
 
 #define OFFSET_FROM_START(tp, off) ((tcp_now + (off)) - (tp)->tentry.timer_start)
 

-#endif /* KERNEL */
-#endif /* PRIVATE */
+#endif /* BSD_KERNEL_PRIVATE */

 #endif /* !_NETINET_TCP_TIMER_H_ */
 #endif /* !_NETINET_TCP_TIMER_H_ */

-