sys/netinet/tcp_hostcache.c

   1 /*-
   2  * Copyright (c) 2002 Andre Oppermann, Internet Business Solutions AG
   3  * 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  * 3. The name of the author may not be used to endorse or promote
  14  *    products derived from this software without specific prior written
  15  *    permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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
  30 /*
  31  * The tcp_hostcache moves the tcp-specific cached metrics from the routing
  32  * table to a dedicated structure indexed by the remote IP address.  It keeps
  33  * information on the measured TCP parameters of past TCP sessions to allow
  34  * better initial start values to be used with later connections to/from the
  35  * same source.  Depending on the network parameters (delay, max MTU,
  36  * congestion window) between local and remote sites, this can lead to
  37  * significant speed-ups for new TCP connections after the first one.
  38  *
  39  * Due to the tcp_hostcache, all TCP-specific metrics information in the
  40  * routing table have been removed.  The inpcb no longer keeps a pointer to
  41  * the routing entry, and protocol-initiated route cloning has been removed
  42  * as well.  With these changes, the routing table has gone back to being
  43  * more lightwight and only carries information related to packet forwarding.
  44  *
  45  * tcp_hostcache is designed for multiple concurrent access in SMP
  46  * environments and high contention.  All bucket rows have their own lock and
  47  * thus multiple lookups and modifies can be done at the same time as long as
  48  * they are in different bucket rows.  If a request for insertion of a new
  49  * record can't be satisfied, it simply returns an empty structure.  Nobody
  50  * and nothing outside of tcp_hostcache.c will ever point directly to any
  51  * entry in the tcp_hostcache.  All communication is done in an
  52  * object-oriented way and only functions of tcp_hostcache will manipulate
  53  * hostcache entries.  Otherwise, we are unable to achieve good behaviour in
  54  * concurrent access situations.  Since tcp_hostcache is only caching
  55  * information, there are no fatal consequences if we either can't satisfy
  56  * any particular request or have to drop/overwrite an existing entry because
  57  * of bucket limit memory constrains.
  58  */
  59
  60 /*
  61  * Many thanks to jlemon for basic structure of tcp_syncache which is being
  62  * followed here.
  63  */
  64
  65 #include <sys/cdefs.h>
  66 __FBSDID("$FreeBSD$");
  67
  68 #include "opt_inet6.h"
  69
  70 #include <sys/param.h>
  71 #include <sys/systm.h>
  72 #include <sys/kernel.h>
  73 #include <sys/lock.h>
  74 #include <sys/mutex.h>
  75 #include <sys/malloc.h>
  76 #include <sys/sbuf.h>
  77 #include <sys/socket.h>
  78 #include <sys/socketvar.h>
  79 #include <sys/sysctl.h>
  80
  81 #include <net/if.h>
  82 #include <net/if_var.h>
  83 #include <net/route.h>
  84 #include <net/vnet.h>
  85
  86 #include <netinet/in.h>
  87 #include <netinet/in_systm.h>
  88 #include <netinet/ip.h>
  89 #include <netinet/in_var.h>
  90 #include <netinet/in_pcb.h>
  91 #include <netinet/ip_var.h>
  92 #ifdef INET6
  93 #include <netinet/ip6.h>
  94 #include <netinet6/ip6_var.h>
  95 #endif
  96 #include <netinet/tcp.h>
  97 #include <netinet/tcp_var.h>
  98 #include <netinet/tcp_hostcache.h>
  99 #ifdef INET6
 100 #include <netinet6/tcp6_var.h>
 101 #endif
 102
 103 #include <vm/uma.h>
 104
 105 /* Arbitrary values */
 106 #define TCP_HOSTCACHE_HASHSIZE          512
 107 #define TCP_HOSTCACHE_BUCKETLIMIT       30
 108 #define TCP_HOSTCACHE_EXPIRE            60*60   /* one hour */
 109 #define TCP_HOSTCACHE_PRUNE             5*60    /* every 5 minutes */
 110
 111 static VNET_DEFINE(struct tcp_hostcache, tcp_hostcache);
 112 #define V_tcp_hostcache         VNET(tcp_hostcache)
 113
 114 static VNET_DEFINE(struct callout, tcp_hc_callout);
 115 #define V_tcp_hc_callout        VNET(tcp_hc_callout)
 116
 117 static struct hc_metrics *tcp_hc_lookup(struct in_conninfo *);
 118 static struct hc_metrics *tcp_hc_insert(struct in_conninfo *);
 119 static int sysctl_tcp_hc_list(SYSCTL_HANDLER_ARGS);
 120 static int sysctl_tcp_hc_purgenow(SYSCTL_HANDLER_ARGS);
 121 static void tcp_hc_purge_internal(int);
 122 static void tcp_hc_purge(void *);
 123
 124 static SYSCTL_NODE(_net_inet_tcp, OID_AUTO, hostcache, CTLFLAG_RW, 0,
 125     "TCP Host cache");
 126
 127 SYSCTL_UINT(_net_inet_tcp_hostcache, OID_AUTO, cachelimit, CTLFLAG_VNET | CTLFLAG_RDTUN,
 128     &VNET_NAME(tcp_hostcache.cache_limit), 0,
 129     "Overall entry limit for hostcache");
 130
 131 SYSCTL_UINT(_net_inet_tcp_hostcache, OID_AUTO, hashsize, CTLFLAG_VNET | CTLFLAG_RDTUN,
 132     &VNET_NAME(tcp_hostcache.hashsize), 0,
 133     "Size of TCP hostcache hashtable");
 134
 135 SYSCTL_UINT(_net_inet_tcp_hostcache, OID_AUTO, bucketlimit,
 136     CTLFLAG_VNET | CTLFLAG_RDTUN, &VNET_NAME(tcp_hostcache.bucket_limit), 0,
 137     "Per-bucket hash limit for hostcache");
 138
 139 SYSCTL_UINT(_net_inet_tcp_hostcache, OID_AUTO, count, CTLFLAG_VNET | CTLFLAG_RD,
 140      &VNET_NAME(tcp_hostcache.cache_count), 0,
 141     "Current number of entries in hostcache");
 142
 143 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, expire, CTLFLAG_VNET | CTLFLAG_RW,
 144     &VNET_NAME(tcp_hostcache.expire), 0,
 145     "Expire time of TCP hostcache entries");
 146
 147 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, prune, CTLFLAG_VNET | CTLFLAG_RW,
 148     &VNET_NAME(tcp_hostcache.prune), 0,
 149     "Time between purge runs");
 150
 151 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, purge, CTLFLAG_VNET | CTLFLAG_RW,
 152     &VNET_NAME(tcp_hostcache.purgeall), 0,
 153     "Expire all entires on next purge run");
 154
 155 SYSCTL_PROC(_net_inet_tcp_hostcache, OID_AUTO, list,
 156     CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_SKIP, 0, 0,
 157     sysctl_tcp_hc_list, "A", "List of all hostcache entries");
 158
 159 SYSCTL_PROC(_net_inet_tcp_hostcache, OID_AUTO, purgenow,
 160     CTLTYPE_INT | CTLFLAG_RW, NULL, 0,
 161     sysctl_tcp_hc_purgenow, "I", "Immediately purge all entries");
 162
 163 static MALLOC_DEFINE(M_HOSTCACHE, "hostcache", "TCP hostcache");
 164
 165 #define HOSTCACHE_HASH(ip) \
 166         (((ip)->s_addr ^ ((ip)->s_addr >> 7) ^ ((ip)->s_addr >> 17)) &  \
 167           V_tcp_hostcache.hashmask)
 168
 169 /* XXX: What is the recommended hash to get good entropy for IPv6 addresses? */
 170 #define HOSTCACHE_HASH6(ip6)                            \
 171         (((ip6)->s6_addr32[0] ^                         \
 172           (ip6)->s6_addr32[1] ^                         \
 173           (ip6)->s6_addr32[2] ^                         \
 174           (ip6)->s6_addr32[3]) &                        \
 175          V_tcp_hostcache.hashmask)
 176
 177 #define THC_LOCK(lp)            mtx_lock(lp)
 178 #define THC_UNLOCK(lp)          mtx_unlock(lp)
 179
 180 void
 181 tcp_hc_init(void)
 182 {
 183         u_int cache_limit;
 184         int i;
 185
 186         /*
 187          * Initialize hostcache structures.
 188          */
 189         V_tcp_hostcache.cache_count = 0;
 190         V_tcp_hostcache.hashsize = TCP_HOSTCACHE_HASHSIZE;
 191         V_tcp_hostcache.bucket_limit = TCP_HOSTCACHE_BUCKETLIMIT;
 192         V_tcp_hostcache.expire = TCP_HOSTCACHE_EXPIRE;
 193         V_tcp_hostcache.prune = TCP_HOSTCACHE_PRUNE;
 194
 195         TUNABLE_INT_FETCH("net.inet.tcp.hostcache.hashsize",
 196             &V_tcp_hostcache.hashsize);
 197         if (!powerof2(V_tcp_hostcache.hashsize)) {
 198                 printf("WARNING: hostcache hash size is not a power of 2.\n");
 199                 V_tcp_hostcache.hashsize = TCP_HOSTCACHE_HASHSIZE; /* default */
 200         }
 201         V_tcp_hostcache.hashmask = V_tcp_hostcache.hashsize - 1;
 202
 203         TUNABLE_INT_FETCH("net.inet.tcp.hostcache.bucketlimit",
 204             &V_tcp_hostcache.bucket_limit);
 205
 206         cache_limit = V_tcp_hostcache.hashsize * V_tcp_hostcache.bucket_limit;
 207         V_tcp_hostcache.cache_limit = cache_limit;
 208         TUNABLE_INT_FETCH("net.inet.tcp.hostcache.cachelimit",
 209             &V_tcp_hostcache.cache_limit);
 210         if (V_tcp_hostcache.cache_limit > cache_limit)
 211                 V_tcp_hostcache.cache_limit = cache_limit;
 212
 213         /*
 214          * Allocate the hash table.
 215          */
 216         V_tcp_hostcache.hashbase = (struct hc_head *)
 217             malloc(V_tcp_hostcache.hashsize * sizeof(struct hc_head),
 218                    M_HOSTCACHE, M_WAITOK | M_ZERO);
 219
 220         /*
 221          * Initialize the hash buckets.
 222          */
 223         for (i = 0; i < V_tcp_hostcache.hashsize; i++) {
 224                 TAILQ_INIT(&V_tcp_hostcache.hashbase[i].hch_bucket);
 225                 V_tcp_hostcache.hashbase[i].hch_length = 0;
 226                 mtx_init(&V_tcp_hostcache.hashbase[i].hch_mtx, "tcp_hc_entry",
 227                           NULL, MTX_DEF);
 228         }
 229
 230         /*
 231          * Allocate the hostcache entries.
 232          */
 233         V_tcp_hostcache.zone =
 234             uma_zcreate("hostcache", sizeof(struct hc_metrics),
 235             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
 236         uma_zone_set_max(V_tcp_hostcache.zone, V_tcp_hostcache.cache_limit);
 237
 238         /*
 239          * Set up periodic cache cleanup.
 240          */
 241         callout_init(&V_tcp_hc_callout, 1);
 242         callout_reset(&V_tcp_hc_callout, V_tcp_hostcache.prune * hz,
 243             tcp_hc_purge, curvnet);
 244 }
 245
 246 #ifdef VIMAGE
 247 void
 248 tcp_hc_destroy(void)
 249 {
 250         int i;
 251
 252         callout_drain(&V_tcp_hc_callout);
 253
 254         /* Purge all hc entries. */
 255         tcp_hc_purge_internal(1);
 256
 257         /* Free the uma zone and the allocated hash table. */
 258         uma_zdestroy(V_tcp_hostcache.zone);
 259
 260         for (i = 0; i < V_tcp_hostcache.hashsize; i++)
 261                 mtx_destroy(&V_tcp_hostcache.hashbase[i].hch_mtx);
 262         free(V_tcp_hostcache.hashbase, M_HOSTCACHE);
 263 }
 264 #endif
 265
 266 /*
 267  * Internal function: look up an entry in the hostcache or return NULL.
 268  *
 269  * If an entry has been returned, the caller becomes responsible for
 270  * unlocking the bucket row after he is done reading/modifying the entry.
 271  */
 272 static struct hc_metrics *
 273 tcp_hc_lookup(struct in_conninfo *inc)
 274 {
 275         int hash;
 276         struct hc_head *hc_head;
 277         struct hc_metrics *hc_entry;
 278
 279         KASSERT(inc != NULL, ("tcp_hc_lookup with NULL in_conninfo pointer"));
 280
 281         /*
 282          * Hash the foreign ip address.
 283          */
 284         if (inc->inc_flags & INC_ISIPV6)
 285                 hash = HOSTCACHE_HASH6(&inc->inc6_faddr);
 286         else
 287                 hash = HOSTCACHE_HASH(&inc->inc_faddr);
 288
 289         hc_head = &V_tcp_hostcache.hashbase[hash];
 290
 291         /*
 292          * Acquire lock for this bucket row; we release the lock if we don't
 293          * find an entry, otherwise the caller has to unlock after he is
 294          * done.
 295          */
 296         THC_LOCK(&hc_head->hch_mtx);
 297
 298         /*
 299          * Iterate through entries in bucket row looking for a match.
 300          */
 301         TAILQ_FOREACH(hc_entry, &hc_head->hch_bucket, rmx_q) {
 302                 if (inc->inc_flags & INC_ISIPV6) {
 303                         /* XXX: check ip6_zoneid */
 304                         if (memcmp(&inc->inc6_faddr, &hc_entry->ip6,
 305                             sizeof(inc->inc6_faddr)) == 0)
 306                                 return hc_entry;
 307                 } else {
 308                         if (memcmp(&inc->inc_faddr, &hc_entry->ip4,
 309                             sizeof(inc->inc_faddr)) == 0)
 310                                 return hc_entry;
 311                 }
 312         }
 313
 314         /*
 315          * We were unsuccessful and didn't find anything.
 316          */
 317         THC_UNLOCK(&hc_head->hch_mtx);
 318         return NULL;
 319 }
 320
 321 /*
 322  * Internal function: insert an entry into the hostcache or return NULL if
 323  * unable to allocate a new one.
 324  *
 325  * If an entry has been returned, the caller becomes responsible for
 326  * unlocking the bucket row after he is done reading/modifying the entry.
 327  */
 328 static struct hc_metrics *
 329 tcp_hc_insert(struct in_conninfo *inc)
 330 {
 331         int hash;
 332         struct hc_head *hc_head;
 333         struct hc_metrics *hc_entry;
 334
 335         KASSERT(inc != NULL, ("tcp_hc_insert with NULL in_conninfo pointer"));
 336
 337         /*
 338          * Hash the foreign ip address.
 339          */
 340         if (inc->inc_flags & INC_ISIPV6)
 341                 hash = HOSTCACHE_HASH6(&inc->inc6_faddr);
 342         else
 343                 hash = HOSTCACHE_HASH(&inc->inc_faddr);
 344
 345         hc_head = &V_tcp_hostcache.hashbase[hash];
 346
 347         /*
 348          * Acquire lock for this bucket row; we release the lock if we don't
 349          * find an entry, otherwise the caller has to unlock after he is
 350          * done.
 351          */
 352         THC_LOCK(&hc_head->hch_mtx);
 353
 354         /*
 355          * If the bucket limit is reached, reuse the least-used element.
 356          */
 357         if (hc_head->hch_length >= V_tcp_hostcache.bucket_limit ||
 358             V_tcp_hostcache.cache_count >= V_tcp_hostcache.cache_limit) {
 359                 hc_entry = TAILQ_LAST(&hc_head->hch_bucket, hc_qhead);
 360                 /*
 361                  * At first we were dropping the last element, just to
 362                  * reacquire it in the next two lines again, which isn't very
 363                  * efficient.  Instead just reuse the least used element.
 364                  * We may drop something that is still "in-use" but we can be
 365                  * "lossy".
 366                  * Just give up if this bucket row is empty and we don't have
 367                  * anything to replace.
 368                  */
 369                 if (hc_entry == NULL) {
 370                         THC_UNLOCK(&hc_head->hch_mtx);
 371                         return NULL;
 372                 }
 373                 TAILQ_REMOVE(&hc_head->hch_bucket, hc_entry, rmx_q);
 374                 V_tcp_hostcache.hashbase[hash].hch_length--;
 375                 V_tcp_hostcache.cache_count--;
 376                 TCPSTAT_INC(tcps_hc_bucketoverflow);
 377 #if 0
 378                 uma_zfree(V_tcp_hostcache.zone, hc_entry);
 379 #endif
 380         } else {
 381                 /*
 382                  * Allocate a new entry, or balk if not possible.
 383                  */
 384                 hc_entry = uma_zalloc(V_tcp_hostcache.zone, M_NOWAIT);
 385                 if (hc_entry == NULL) {
 386                         THC_UNLOCK(&hc_head->hch_mtx);
 387                         return NULL;
 388                 }
 389         }
 390
 391         /*
 392          * Initialize basic information of hostcache entry.
 393          */
 394         bzero(hc_entry, sizeof(*hc_entry));
 395         if (inc->inc_flags & INC_ISIPV6) {
 396                 hc_entry->ip6 = inc->inc6_faddr;
 397                 hc_entry->ip6_zoneid = inc->inc6_zoneid;
 398         } else
 399                 hc_entry->ip4 = inc->inc_faddr;
 400         hc_entry->rmx_head = hc_head;
 401         hc_entry->rmx_expire = V_tcp_hostcache.expire;
 402
 403         /*
 404          * Put it upfront.
 405          */
 406         TAILQ_INSERT_HEAD(&hc_head->hch_bucket, hc_entry, rmx_q);
 407         V_tcp_hostcache.hashbase[hash].hch_length++;
 408         V_tcp_hostcache.cache_count++;
 409         TCPSTAT_INC(tcps_hc_added);
 410
 411         return hc_entry;
 412 }
 413
 414 /*
 415  * External function: look up an entry in the hostcache and fill out the
 416  * supplied TCP metrics structure.  Fills in NULL when no entry was found or
 417  * a value is not set.
 418  */
 419 void
 420 tcp_hc_get(struct in_conninfo *inc, struct hc_metrics_lite *hc_metrics_lite)
 421 {
 422         struct hc_metrics *hc_entry;
 423
 424         /*
 425          * Find the right bucket.
 426          */
 427         hc_entry = tcp_hc_lookup(inc);
 428
 429         /*
 430          * If we don't have an existing object.
 431          */
 432         if (hc_entry == NULL) {
 433                 bzero(hc_metrics_lite, sizeof(*hc_metrics_lite));
 434                 return;
 435         }
 436         hc_entry->rmx_hits++;
 437         hc_entry->rmx_expire = V_tcp_hostcache.expire; /* start over again */
 438
 439         hc_metrics_lite->rmx_mtu = hc_entry->rmx_mtu;
 440         hc_metrics_lite->rmx_ssthresh = hc_entry->rmx_ssthresh;
 441         hc_metrics_lite->rmx_rtt = hc_entry->rmx_rtt;
 442         hc_metrics_lite->rmx_rttvar = hc_entry->rmx_rttvar;
 443         hc_metrics_lite->rmx_cwnd = hc_entry->rmx_cwnd;
 444         hc_metrics_lite->rmx_sendpipe = hc_entry->rmx_sendpipe;
 445         hc_metrics_lite->rmx_recvpipe = hc_entry->rmx_recvpipe;
 446
 447         /*
 448          * Unlock bucket row.
 449          */
 450         THC_UNLOCK(&hc_entry->rmx_head->hch_mtx);
 451 }
 452
 453 /*
 454  * External function: look up an entry in the hostcache and return the
 455  * discovered path MTU.  Returns NULL if no entry is found or value is not
 456  * set.
 457  */
 458 u_long
 459 tcp_hc_getmtu(struct in_conninfo *inc)
 460 {
 461         struct hc_metrics *hc_entry;
 462         u_long mtu;
 463
 464         hc_entry = tcp_hc_lookup(inc);
 465         if (hc_entry == NULL) {
 466                 return 0;
 467         }
 468         hc_entry->rmx_hits++;
 469         hc_entry->rmx_expire = V_tcp_hostcache.expire; /* start over again */
 470
 471         mtu = hc_entry->rmx_mtu;
 472         THC_UNLOCK(&hc_entry->rmx_head->hch_mtx);
 473         return mtu;
 474 }
 475
 476 /*
 477  * External function: update the MTU value of an entry in the hostcache.
 478  * Creates a new entry if none was found.
 479  */
 480 void
 481 tcp_hc_updatemtu(struct in_conninfo *inc, u_long mtu)
 482 {
 483         struct hc_metrics *hc_entry;
 484
 485         /*
 486          * Find the right bucket.
 487          */
 488         hc_entry = tcp_hc_lookup(inc);
 489
 490         /*
 491          * If we don't have an existing object, try to insert a new one.
 492          */
 493         if (hc_entry == NULL) {
 494                 hc_entry = tcp_hc_insert(inc);
 495                 if (hc_entry == NULL)
 496                         return;
 497         }
 498         hc_entry->rmx_updates++;
 499         hc_entry->rmx_expire = V_tcp_hostcache.expire; /* start over again */
 500
 501         hc_entry->rmx_mtu = mtu;
 502
 503         /*
 504          * Put it upfront so we find it faster next time.
 505          */
 506         TAILQ_REMOVE(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q);
 507         TAILQ_INSERT_HEAD(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q);
 508
 509         /*
 510          * Unlock bucket row.
 511          */
 512         THC_UNLOCK(&hc_entry->rmx_head->hch_mtx);
 513 }
 514
 515 /*
 516  * External function: update the TCP metrics of an entry in the hostcache.
 517  * Creates a new entry if none was found.
 518  */
 519 void
 520 tcp_hc_update(struct in_conninfo *inc, struct hc_metrics_lite *hcml)
 521 {
 522         struct hc_metrics *hc_entry;
 523
 524         hc_entry = tcp_hc_lookup(inc);
 525         if (hc_entry == NULL) {
 526                 hc_entry = tcp_hc_insert(inc);
 527                 if (hc_entry == NULL)
 528                         return;
 529         }
 530         hc_entry->rmx_updates++;
 531         hc_entry->rmx_expire = V_tcp_hostcache.expire; /* start over again */
 532
 533         if (hcml->rmx_rtt != 0) {
 534                 if (hc_entry->rmx_rtt == 0)
 535                         hc_entry->rmx_rtt = hcml->rmx_rtt;
 536                 else
 537                         hc_entry->rmx_rtt =
 538                             (hc_entry->rmx_rtt + hcml->rmx_rtt) / 2;
 539                 TCPSTAT_INC(tcps_cachedrtt);
 540         }
 541         if (hcml->rmx_rttvar != 0) {
 542                 if (hc_entry->rmx_rttvar == 0)
 543                         hc_entry->rmx_rttvar = hcml->rmx_rttvar;
 544                 else
 545                         hc_entry->rmx_rttvar =
 546                             (hc_entry->rmx_rttvar + hcml->rmx_rttvar) / 2;
 547                 TCPSTAT_INC(tcps_cachedrttvar);
 548         }
 549         if (hcml->rmx_ssthresh != 0) {
 550                 if (hc_entry->rmx_ssthresh == 0)
 551                         hc_entry->rmx_ssthresh = hcml->rmx_ssthresh;
 552                 else
 553                         hc_entry->rmx_ssthresh =
 554                             (hc_entry->rmx_ssthresh + hcml->rmx_ssthresh) / 2;
 555                 TCPSTAT_INC(tcps_cachedssthresh);
 556         }
 557         if (hcml->rmx_cwnd != 0) {
 558                 if (hc_entry->rmx_cwnd == 0)
 559                         hc_entry->rmx_cwnd = hcml->rmx_cwnd;
 560                 else
 561                         hc_entry->rmx_cwnd =
 562                             (hc_entry->rmx_cwnd + hcml->rmx_cwnd) / 2;
 563                 /* TCPSTAT_INC(tcps_cachedcwnd); */
 564         }
 565         if (hcml->rmx_sendpipe != 0) {
 566                 if (hc_entry->rmx_sendpipe == 0)
 567                         hc_entry->rmx_sendpipe = hcml->rmx_sendpipe;
 568                 else
 569                         hc_entry->rmx_sendpipe =
 570                             (hc_entry->rmx_sendpipe + hcml->rmx_sendpipe) /2;
 571                 /* TCPSTAT_INC(tcps_cachedsendpipe); */
 572         }
 573         if (hcml->rmx_recvpipe != 0) {
 574                 if (hc_entry->rmx_recvpipe == 0)
 575                         hc_entry->rmx_recvpipe = hcml->rmx_recvpipe;
 576                 else
 577                         hc_entry->rmx_recvpipe =
 578                             (hc_entry->rmx_recvpipe + hcml->rmx_recvpipe) /2;
 579                 /* TCPSTAT_INC(tcps_cachedrecvpipe); */
 580         }
 581
 582         TAILQ_REMOVE(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q);
 583         TAILQ_INSERT_HEAD(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q);
 584         THC_UNLOCK(&hc_entry->rmx_head->hch_mtx);
 585 }
 586
 587 /*
 588  * Sysctl function: prints the list and values of all hostcache entries in
 589  * unsorted order.
 590  */
 591 static int
 592 sysctl_tcp_hc_list(SYSCTL_HANDLER_ARGS)
 593 {
 594         const int linesize = 128;
 595         struct sbuf sb;
 596         int i, error;
 597         struct hc_metrics *hc_entry;
 598 #ifdef INET6
 599         char ip6buf[INET6_ADDRSTRLEN];
 600 #endif
 601
 602         sbuf_new(&sb, NULL, linesize * (V_tcp_hostcache.cache_count + 1),
 603                 SBUF_INCLUDENUL);
 604
 605         sbuf_printf(&sb,
 606                 "\nIP address        MTU  SSTRESH      RTT   RTTVAR "
 607                 "    CWND SENDPIPE RECVPIPE HITS  UPD  EXP\n");
 608
 609 #define msec(u) (((u) + 500) / 1000)
 610         for (i = 0; i < V_tcp_hostcache.hashsize; i++) {
 611                 THC_LOCK(&V_tcp_hostcache.hashbase[i].hch_mtx);
 612                 TAILQ_FOREACH(hc_entry, &V_tcp_hostcache.hashbase[i].hch_bucket,
 613                               rmx_q) {
 614                         sbuf_printf(&sb,
 615                             "%-15s %5lu %8lu %6lums %6lums %8lu %8lu %8lu %4lu "
 616                             "%4lu %4i\n",
 617                             hc_entry->ip4.s_addr ? inet_ntoa(hc_entry->ip4) :
 618 #ifdef INET6
 619                                 ip6_sprintf(ip6buf, &hc_entry->ip6),
 620 #else
 621                                 "IPv6?",
 622 #endif
 623                             hc_entry->rmx_mtu,
 624                             hc_entry->rmx_ssthresh,
 625                             msec(hc_entry->rmx_rtt *
 626                                 (RTM_RTTUNIT / (hz * TCP_RTT_SCALE))),
 627                             msec(hc_entry->rmx_rttvar *
 628                                 (RTM_RTTUNIT / (hz * TCP_RTTVAR_SCALE))),
 629                             hc_entry->rmx_cwnd,
 630                             hc_entry->rmx_sendpipe,
 631                             hc_entry->rmx_recvpipe,
 632                             hc_entry->rmx_hits,
 633                             hc_entry->rmx_updates,
 634                             hc_entry->rmx_expire);
 635                 }
 636                 THC_UNLOCK(&V_tcp_hostcache.hashbase[i].hch_mtx);
 637         }
 638 #undef msec
 639         error = sbuf_finish(&sb);
 640         if (error == 0)
 641                 error = SYSCTL_OUT(req, sbuf_data(&sb), sbuf_len(&sb));
 642         sbuf_delete(&sb);
 643         return(error);
 644 }
 645
 646 /*
 647  * Caller has to make sure the curvnet is set properly.
 648  */
 649 static void
 650 tcp_hc_purge_internal(int all)
 651 {
 652         struct hc_metrics *hc_entry, *hc_next;
 653         int i;
 654
 655         for (i = 0; i < V_tcp_hostcache.hashsize; i++) {
 656                 THC_LOCK(&V_tcp_hostcache.hashbase[i].hch_mtx);
 657                 TAILQ_FOREACH_SAFE(hc_entry,
 658                     &V_tcp_hostcache.hashbase[i].hch_bucket, rmx_q, hc_next) {
 659                         if (all || hc_entry->rmx_expire <= 0) {
 660                                 TAILQ_REMOVE(&V_tcp_hostcache.hashbase[i].hch_bucket,
 661                                               hc_entry, rmx_q);
 662                                 uma_zfree(V_tcp_hostcache.zone, hc_entry);
 663                                 V_tcp_hostcache.hashbase[i].hch_length--;
 664                                 V_tcp_hostcache.cache_count--;
 665                         } else
 666                                 hc_entry->rmx_expire -= V_tcp_hostcache.prune;
 667                 }
 668                 THC_UNLOCK(&V_tcp_hostcache.hashbase[i].hch_mtx);
 669         }
 670 }
 671
 672 /*
 673  * Expire and purge (old|all) entries in the tcp_hostcache.  Runs
 674  * periodically from the callout.
 675  */
 676 static void
 677 tcp_hc_purge(void *arg)
 678 {
 679         CURVNET_SET((struct vnet *) arg);
 680         int all = 0;
 681
 682         if (V_tcp_hostcache.purgeall) {
 683                 all = 1;
 684                 V_tcp_hostcache.purgeall = 0;
 685         }
 686
 687         tcp_hc_purge_internal(all);
 688
 689         callout_reset(&V_tcp_hc_callout, V_tcp_hostcache.prune * hz,
 690             tcp_hc_purge, arg);
 691         CURVNET_RESTORE();
 692 }
 693
 694 /*
 695  * Expire and purge all entries in hostcache immediately.
 696  */
 697 static int
 698 sysctl_tcp_hc_purgenow(SYSCTL_HANDLER_ARGS)
 699 {
 700         int error, val;
 701
 702         val = 0;
 703         error = sysctl_handle_int(oidp, &val, 0, req);
 704         if (error || !req->newptr)
 705                 return (error);
 706
 707         tcp_hc_purge_internal(1);
 708
 709         callout_reset(&V_tcp_hc_callout, V_tcp_hostcache.prune * hz,
 710             tcp_hc_purge, curvnet);
 711
 712         return (0);
 713 }