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, bandwidth, max
  36  * MTU, 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/socket.h>
  77 #include <sys/socketvar.h>
  78 #include <sys/sysctl.h>
  79
  80 #include <net/if.h>
  81 #include <net/route.h>
  82 #include <net/vnet.h>
  83
  84 #include <netinet/in.h>
  85 #include <netinet/in_systm.h>
  86 #include <netinet/ip.h>
  87 #include <netinet/in_var.h>
  88 #include <netinet/in_pcb.h>
  89 #include <netinet/ip_var.h>
  90 #ifdef INET6
  91 #include <netinet/ip6.h>
  92 #include <netinet6/ip6_var.h>
  93 #endif
  94 #include <netinet/tcp.h>
  95 #include <netinet/tcp_var.h>
  96 #include <netinet/tcp_hostcache.h>
  97 #ifdef INET6
  98 #include <netinet6/tcp6_var.h>
  99 #endif
 100
 101 #include <vm/uma.h>
 102
 103 /* Arbitrary values */
 104 #define TCP_HOSTCACHE_HASHSIZE          512
 105 #define TCP_HOSTCACHE_BUCKETLIMIT       30
 106 #define TCP_HOSTCACHE_EXPIRE            60*60   /* one hour */
 107 #define TCP_HOSTCACHE_PRUNE             5*60    /* every 5 minutes */
 108
 109 static VNET_DEFINE(struct tcp_hostcache, tcp_hostcache);
 110 static VNET_DEFINE(struct callout, tcp_hc_callout);
 111
 112 #define V_tcp_hostcache         VNET(tcp_hostcache)
 113 #define V_tcp_hc_callout        VNET(tcp_hc_callout)
 114
 115 static struct hc_metrics *tcp_hc_lookup(struct in_conninfo *);
 116 static struct hc_metrics *tcp_hc_insert(struct in_conninfo *);
 117 static int sysctl_tcp_hc_list(SYSCTL_HANDLER_ARGS);
 118 static void tcp_hc_purge(void *);
 119
 120 SYSCTL_NODE(_net_inet_tcp, OID_AUTO, hostcache, CTLFLAG_RW, 0,
 121     "TCP Host cache");
 122
 123 SYSCTL_VNET_INT(_net_inet_tcp_hostcache, OID_AUTO, cachelimit, CTLFLAG_RDTUN,
 124     &VNET_NAME(tcp_hostcache.cache_limit), 0,
 125     "Overall entry limit for hostcache");
 126
 127 SYSCTL_VNET_INT(_net_inet_tcp_hostcache, OID_AUTO, hashsize, CTLFLAG_RDTUN,
 128     &VNET_NAME(tcp_hostcache.hashsize), 0,
 129     "Size of TCP hostcache hashtable");
 130
 131 SYSCTL_VNET_INT(_net_inet_tcp_hostcache, OID_AUTO, bucketlimit,
 132     CTLFLAG_RDTUN, &VNET_NAME(tcp_hostcache.bucket_limit), 0,
 133     "Per-bucket hash limit for hostcache");
 134
 135 SYSCTL_VNET_INT(_net_inet_tcp_hostcache, OID_AUTO, count, CTLFLAG_RD,
 136      &VNET_NAME(tcp_hostcache.cache_count), 0,
 137     "Current number of entries in hostcache");
 138
 139 SYSCTL_VNET_INT(_net_inet_tcp_hostcache, OID_AUTO, expire, CTLFLAG_RW,
 140     &VNET_NAME(tcp_hostcache.expire), 0,
 141     "Expire time of TCP hostcache entries");
 142
 143 SYSCTL_VNET_INT(_net_inet_tcp_hostcache, OID_AUTO, prune, CTLFLAG_RW,
 144     &VNET_NAME(tcp_hostcache.prune), 0,
 145     "Time between purge runs");
 146
 147 SYSCTL_VNET_INT(_net_inet_tcp_hostcache, OID_AUTO, purge, CTLFLAG_RW,
 148     &VNET_NAME(tcp_hostcache.purgeall), 0,
 149     "Expire all entires on next purge run");
 150
 151 SYSCTL_PROC(_net_inet_tcp_hostcache, OID_AUTO, list,
 152     CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_SKIP, 0, 0,
 153     sysctl_tcp_hc_list, "A", "List of all hostcache entries");
 154
 155
 156 static MALLOC_DEFINE(M_HOSTCACHE, "hostcache", "TCP hostcache");
 157
 158 #define HOSTCACHE_HASH(ip) \
 159         (((ip)->s_addr ^ ((ip)->s_addr >> 7) ^ ((ip)->s_addr >> 17)) &  \
 160           V_tcp_hostcache.hashmask)
 161
 162 /* XXX: What is the recommended hash to get good entropy for IPv6 addresses? */
 163 #define HOSTCACHE_HASH6(ip6)                            \
 164         (((ip6)->s6_addr32[0] ^                         \
 165           (ip6)->s6_addr32[1] ^                         \
 166           (ip6)->s6_addr32[2] ^                         \
 167           (ip6)->s6_addr32[3]) &                        \
 168          V_tcp_hostcache.hashmask)
 169
 170 #define THC_LOCK(lp)            mtx_lock(lp)
 171 #define THC_UNLOCK(lp)          mtx_unlock(lp)
 172
 173 void
 174 tcp_hc_init(void)
 175 {
 176         int i;
 177
 178         /*
 179          * Initialize hostcache structures.
 180          */
 181         V_tcp_hostcache.cache_count = 0;
 182         V_tcp_hostcache.hashsize = TCP_HOSTCACHE_HASHSIZE;
 183         V_tcp_hostcache.bucket_limit = TCP_HOSTCACHE_BUCKETLIMIT;
 184         V_tcp_hostcache.cache_limit =
 185             V_tcp_hostcache.hashsize * V_tcp_hostcache.bucket_limit;
 186         V_tcp_hostcache.expire = TCP_HOSTCACHE_EXPIRE;
 187         V_tcp_hostcache.prune = TCP_HOSTCACHE_PRUNE;
 188
 189         TUNABLE_INT_FETCH("net.inet.tcp.hostcache.hashsize",
 190             &V_tcp_hostcache.hashsize);
 191         TUNABLE_INT_FETCH("net.inet.tcp.hostcache.cachelimit",
 192             &V_tcp_hostcache.cache_limit);
 193         TUNABLE_INT_FETCH("net.inet.tcp.hostcache.bucketlimit",
 194             &V_tcp_hostcache.bucket_limit);
 195         if (!powerof2(V_tcp_hostcache.hashsize)) {
 196                 printf("WARNING: hostcache hash size is not a power of 2.\n");
 197                 V_tcp_hostcache.hashsize = TCP_HOSTCACHE_HASHSIZE; /* default */
 198         }
 199         V_tcp_hostcache.hashmask = V_tcp_hostcache.hashsize - 1;
 200
 201         /*
 202          * Allocate the hash table.
 203          */
 204         V_tcp_hostcache.hashbase = (struct hc_head *)
 205             malloc(V_tcp_hostcache.hashsize * sizeof(struct hc_head),
 206                    M_HOSTCACHE, M_WAITOK | M_ZERO);
 207
 208         /*
 209          * Initialize the hash buckets.
 210          */
 211         for (i = 0; i < V_tcp_hostcache.hashsize; i++) {
 212                 TAILQ_INIT(&V_tcp_hostcache.hashbase[i].hch_bucket);
 213                 V_tcp_hostcache.hashbase[i].hch_length = 0;
 214                 mtx_init(&V_tcp_hostcache.hashbase[i].hch_mtx, "tcp_hc_entry",
 215                           NULL, MTX_DEF);
 216         }
 217
 218         /*
 219          * Allocate the hostcache entries.
 220          */
 221         V_tcp_hostcache.zone =
 222             uma_zcreate("hostcache", sizeof(struct hc_metrics),
 223             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
 224         uma_zone_set_max(V_tcp_hostcache.zone, V_tcp_hostcache.cache_limit);
 225
 226         /*
 227          * Set up periodic cache cleanup.
 228          */
 229         callout_init(&V_tcp_hc_callout, CALLOUT_MPSAFE);
 230         callout_reset(&V_tcp_hc_callout, V_tcp_hostcache.prune * hz,
 231             tcp_hc_purge, curvnet);
 232 }
 233
 234 #ifdef VIMAGE
 235 void
 236 tcp_hc_destroy(void)
 237 {
 238
 239         /* XXX TODO walk the hashtable and free all entries  */
 240
 241         callout_drain(&V_tcp_hc_callout);
 242 }
 243 #endif
 244
 245 /*
 246  * Internal function: look up an entry in the hostcache or return NULL.
 247  *
 248  * If an entry has been returned, the caller becomes responsible for
 249  * unlocking the bucket row after he is done reading/modifying the entry.
 250  */
 251 static struct hc_metrics *
 252 tcp_hc_lookup(struct in_conninfo *inc)
 253 {
 254         int hash;
 255         struct hc_head *hc_head;
 256         struct hc_metrics *hc_entry;
 257
 258         KASSERT(inc != NULL, ("tcp_hc_lookup with NULL in_conninfo pointer"));
 259
 260         /*
 261          * Hash the foreign ip address.
 262          */
 263         if (inc->inc_flags & INC_ISIPV6)
 264                 hash = HOSTCACHE_HASH6(&inc->inc6_faddr);
 265         else
 266                 hash = HOSTCACHE_HASH(&inc->inc_faddr);
 267
 268         hc_head = &V_tcp_hostcache.hashbase[hash];
 269
 270         /*
 271          * Acquire lock for this bucket row; we release the lock if we don't
 272          * find an entry, otherwise the caller has to unlock after he is
 273          * done.
 274          */
 275         THC_LOCK(&hc_head->hch_mtx);
 276
 277         /*
 278          * Iterate through entries in bucket row looking for a match.
 279          */
 280         TAILQ_FOREACH(hc_entry, &hc_head->hch_bucket, rmx_q) {
 281                 if (inc->inc_flags & INC_ISIPV6) {
 282                         if (memcmp(&inc->inc6_faddr, &hc_entry->ip6,
 283                             sizeof(inc->inc6_faddr)) == 0)
 284                                 return hc_entry;
 285                 } else {
 286                         if (memcmp(&inc->inc_faddr, &hc_entry->ip4,
 287                             sizeof(inc->inc_faddr)) == 0)
 288                                 return hc_entry;
 289                 }
 290         }
 291
 292         /*
 293          * We were unsuccessful and didn't find anything.
 294          */
 295         THC_UNLOCK(&hc_head->hch_mtx);
 296         return NULL;
 297 }
 298
 299 /*
 300  * Internal function: insert an entry into the hostcache or return NULL if
 301  * unable to allocate a new one.
 302  *
 303  * If an entry has been returned, the caller becomes responsible for
 304  * unlocking the bucket row after he is done reading/modifying the entry.
 305  */
 306 static struct hc_metrics *
 307 tcp_hc_insert(struct in_conninfo *inc)
 308 {
 309         int hash;
 310         struct hc_head *hc_head;
 311         struct hc_metrics *hc_entry;
 312
 313         KASSERT(inc != NULL, ("tcp_hc_insert with NULL in_conninfo pointer"));
 314
 315         /*
 316          * Hash the foreign ip address.
 317          */
 318         if (inc->inc_flags & INC_ISIPV6)
 319                 hash = HOSTCACHE_HASH6(&inc->inc6_faddr);
 320         else
 321                 hash = HOSTCACHE_HASH(&inc->inc_faddr);
 322
 323         hc_head = &V_tcp_hostcache.hashbase[hash];
 324
 325         /*
 326          * Acquire lock for this bucket row; we release the lock if we don't
 327          * find an entry, otherwise the caller has to unlock after he is
 328          * done.
 329          */
 330         THC_LOCK(&hc_head->hch_mtx);
 331
 332         /*
 333          * If the bucket limit is reached, reuse the least-used element.
 334          */
 335         if (hc_head->hch_length >= V_tcp_hostcache.bucket_limit ||
 336             V_tcp_hostcache.cache_count >= V_tcp_hostcache.cache_limit) {
 337                 hc_entry = TAILQ_LAST(&hc_head->hch_bucket, hc_qhead);
 338                 /*
 339                  * At first we were dropping the last element, just to
 340                  * reacquire it in the next two lines again, which isn't very
 341                  * efficient.  Instead just reuse the least used element.
 342                  * We may drop something that is still "in-use" but we can be
 343                  * "lossy".
 344                  * Just give up if this bucket row is empty and we don't have
 345                  * anything to replace.
 346                  */
 347                 if (hc_entry == NULL) {
 348                         THC_UNLOCK(&hc_head->hch_mtx);
 349                         return NULL;
 350                 }
 351                 TAILQ_REMOVE(&hc_head->hch_bucket, hc_entry, rmx_q);
 352                 V_tcp_hostcache.hashbase[hash].hch_length--;
 353                 V_tcp_hostcache.cache_count--;
 354                 TCPSTAT_INC(tcps_hc_bucketoverflow);
 355 #if 0
 356                 uma_zfree(V_tcp_hostcache.zone, hc_entry);
 357 #endif
 358         } else {
 359                 /*
 360                  * Allocate a new entry, or balk if not possible.
 361                  */
 362                 hc_entry = uma_zalloc(V_tcp_hostcache.zone, M_NOWAIT);
 363                 if (hc_entry == NULL) {
 364                         THC_UNLOCK(&hc_head->hch_mtx);
 365                         return NULL;
 366                 }
 367         }
 368
 369         /*
 370          * Initialize basic information of hostcache entry.
 371          */
 372         bzero(hc_entry, sizeof(*hc_entry));
 373         if (inc->inc_flags & INC_ISIPV6)
 374                 bcopy(&inc->inc6_faddr, &hc_entry->ip6, sizeof(hc_entry->ip6));
 375         else
 376                 hc_entry->ip4 = inc->inc_faddr;
 377         hc_entry->rmx_head = hc_head;
 378         hc_entry->rmx_expire = V_tcp_hostcache.expire;
 379
 380         /*
 381          * Put it upfront.
 382          */
 383         TAILQ_INSERT_HEAD(&hc_head->hch_bucket, hc_entry, rmx_q);
 384         V_tcp_hostcache.hashbase[hash].hch_length++;
 385         V_tcp_hostcache.cache_count++;
 386         TCPSTAT_INC(tcps_hc_added);
 387
 388         return hc_entry;
 389 }
 390
 391 /*
 392  * External function: look up an entry in the hostcache and fill out the
 393  * supplied TCP metrics structure.  Fills in NULL when no entry was found or
 394  * a value is not set.
 395  */
 396 void
 397 tcp_hc_get(struct in_conninfo *inc, struct hc_metrics_lite *hc_metrics_lite)
 398 {
 399         struct hc_metrics *hc_entry;
 400
 401         /*
 402          * Find the right bucket.
 403          */
 404         hc_entry = tcp_hc_lookup(inc);
 405
 406         /*
 407          * If we don't have an existing object.
 408          */
 409         if (hc_entry == NULL) {
 410                 bzero(hc_metrics_lite, sizeof(*hc_metrics_lite));
 411                 return;
 412         }
 413         hc_entry->rmx_hits++;
 414         hc_entry->rmx_expire = V_tcp_hostcache.expire; /* start over again */
 415
 416         hc_metrics_lite->rmx_mtu = hc_entry->rmx_mtu;
 417         hc_metrics_lite->rmx_ssthresh = hc_entry->rmx_ssthresh;
 418         hc_metrics_lite->rmx_rtt = hc_entry->rmx_rtt;
 419         hc_metrics_lite->rmx_rttvar = hc_entry->rmx_rttvar;
 420         hc_metrics_lite->rmx_bandwidth = hc_entry->rmx_bandwidth;
 421         hc_metrics_lite->rmx_cwnd = hc_entry->rmx_cwnd;
 422         hc_metrics_lite->rmx_sendpipe = hc_entry->rmx_sendpipe;
 423         hc_metrics_lite->rmx_recvpipe = hc_entry->rmx_recvpipe;
 424
 425         /*
 426          * Unlock bucket row.
 427          */
 428         THC_UNLOCK(&hc_entry->rmx_head->hch_mtx);
 429 }
 430
 431 /*
 432  * External function: look up an entry in the hostcache and return the
 433  * discovered path MTU.  Returns NULL if no entry is found or value is not
 434  * set.
 435  */
 436 u_long
 437 tcp_hc_getmtu(struct in_conninfo *inc)
 438 {
 439         struct hc_metrics *hc_entry;
 440         u_long mtu;
 441
 442         hc_entry = tcp_hc_lookup(inc);
 443         if (hc_entry == NULL) {
 444                 return 0;
 445         }
 446         hc_entry->rmx_hits++;
 447         hc_entry->rmx_expire = V_tcp_hostcache.expire; /* start over again */
 448
 449         mtu = hc_entry->rmx_mtu;
 450         THC_UNLOCK(&hc_entry->rmx_head->hch_mtx);
 451         return mtu;
 452 }
 453
 454 /*
 455  * External function: update the MTU value of an entry in the hostcache.
 456  * Creates a new entry if none was found.
 457  */
 458 void
 459 tcp_hc_updatemtu(struct in_conninfo *inc, u_long mtu)
 460 {
 461         struct hc_metrics *hc_entry;
 462
 463         /*
 464          * Find the right bucket.
 465          */
 466         hc_entry = tcp_hc_lookup(inc);
 467
 468         /*
 469          * If we don't have an existing object, try to insert a new one.
 470          */
 471         if (hc_entry == NULL) {
 472                 hc_entry = tcp_hc_insert(inc);
 473                 if (hc_entry == NULL)
 474                         return;
 475         }
 476         hc_entry->rmx_updates++;
 477         hc_entry->rmx_expire = V_tcp_hostcache.expire; /* start over again */
 478
 479         hc_entry->rmx_mtu = mtu;
 480
 481         /*
 482          * Put it upfront so we find it faster next time.
 483          */
 484         TAILQ_REMOVE(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q);
 485         TAILQ_INSERT_HEAD(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q);
 486
 487         /*
 488          * Unlock bucket row.
 489          */
 490         THC_UNLOCK(&hc_entry->rmx_head->hch_mtx);
 491 }
 492
 493 /*
 494  * External function: update the TCP metrics of an entry in the hostcache.
 495  * Creates a new entry if none was found.
 496  */
 497 void
 498 tcp_hc_update(struct in_conninfo *inc, struct hc_metrics_lite *hcml)
 499 {
 500         struct hc_metrics *hc_entry;
 501
 502         hc_entry = tcp_hc_lookup(inc);
 503         if (hc_entry == NULL) {
 504                 hc_entry = tcp_hc_insert(inc);
 505                 if (hc_entry == NULL)
 506                         return;
 507         }
 508         hc_entry->rmx_updates++;
 509         hc_entry->rmx_expire = V_tcp_hostcache.expire; /* start over again */
 510
 511         if (hcml->rmx_rtt != 0) {
 512                 if (hc_entry->rmx_rtt == 0)
 513                         hc_entry->rmx_rtt = hcml->rmx_rtt;
 514                 else
 515                         hc_entry->rmx_rtt =
 516                             (hc_entry->rmx_rtt + hcml->rmx_rtt) / 2;
 517                 TCPSTAT_INC(tcps_cachedrtt);
 518         }
 519         if (hcml->rmx_rttvar != 0) {
 520                 if (hc_entry->rmx_rttvar == 0)
 521                         hc_entry->rmx_rttvar = hcml->rmx_rttvar;
 522                 else
 523                         hc_entry->rmx_rttvar =
 524                             (hc_entry->rmx_rttvar + hcml->rmx_rttvar) / 2;
 525                 TCPSTAT_INC(tcps_cachedrttvar);
 526         }
 527         if (hcml->rmx_ssthresh != 0) {
 528                 if (hc_entry->rmx_ssthresh == 0)
 529                         hc_entry->rmx_ssthresh = hcml->rmx_ssthresh;
 530                 else
 531                         hc_entry->rmx_ssthresh =
 532                             (hc_entry->rmx_ssthresh + hcml->rmx_ssthresh) / 2;
 533                 TCPSTAT_INC(tcps_cachedssthresh);
 534         }
 535         if (hcml->rmx_bandwidth != 0) {
 536                 if (hc_entry->rmx_bandwidth == 0)
 537                         hc_entry->rmx_bandwidth = hcml->rmx_bandwidth;
 538                 else
 539                         hc_entry->rmx_bandwidth =
 540                             (hc_entry->rmx_bandwidth + hcml->rmx_bandwidth) / 2;
 541                 /* TCPSTAT_INC(tcps_cachedbandwidth); */
 542         }
 543         if (hcml->rmx_cwnd != 0) {
 544                 if (hc_entry->rmx_cwnd == 0)
 545                         hc_entry->rmx_cwnd = hcml->rmx_cwnd;
 546                 else
 547                         hc_entry->rmx_cwnd =
 548                             (hc_entry->rmx_cwnd + hcml->rmx_cwnd) / 2;
 549                 /* TCPSTAT_INC(tcps_cachedcwnd); */
 550         }
 551         if (hcml->rmx_sendpipe != 0) {
 552                 if (hc_entry->rmx_sendpipe == 0)
 553                         hc_entry->rmx_sendpipe = hcml->rmx_sendpipe;
 554                 else
 555                         hc_entry->rmx_sendpipe =
 556                             (hc_entry->rmx_sendpipe + hcml->rmx_sendpipe) /2;
 557                 /* TCPSTAT_INC(tcps_cachedsendpipe); */
 558         }
 559         if (hcml->rmx_recvpipe != 0) {
 560                 if (hc_entry->rmx_recvpipe == 0)
 561                         hc_entry->rmx_recvpipe = hcml->rmx_recvpipe;
 562                 else
 563                         hc_entry->rmx_recvpipe =
 564                             (hc_entry->rmx_recvpipe + hcml->rmx_recvpipe) /2;
 565                 /* TCPSTAT_INC(tcps_cachedrecvpipe); */
 566         }
 567
 568         TAILQ_REMOVE(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q);
 569         TAILQ_INSERT_HEAD(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q);
 570         THC_UNLOCK(&hc_entry->rmx_head->hch_mtx);
 571 }
 572
 573 /*
 574  * Sysctl function: prints the list and values of all hostcache entries in
 575  * unsorted order.
 576  */
 577 static int
 578 sysctl_tcp_hc_list(SYSCTL_HANDLER_ARGS)
 579 {
 580         int bufsize;
 581         int linesize = 128;
 582         char *p, *buf;
 583         int len, i, error;
 584         struct hc_metrics *hc_entry;
 585 #ifdef INET6
 586         char ip6buf[INET6_ADDRSTRLEN];
 587 #endif
 588
 589         bufsize = linesize * (V_tcp_hostcache.cache_count + 1);
 590
 591         p = buf = (char *)malloc(bufsize, M_TEMP, M_WAITOK|M_ZERO);
 592
 593         len = snprintf(p, linesize,
 594                 "\nIP address        MTU  SSTRESH      RTT   RTTVAR BANDWIDTH "
 595                 "    CWND SENDPIPE RECVPIPE HITS  UPD  EXP\n");
 596         p += len;
 597
 598 #define msec(u) (((u) + 500) / 1000)
 599         for (i = 0; i < V_tcp_hostcache.hashsize; i++) {
 600                 THC_LOCK(&V_tcp_hostcache.hashbase[i].hch_mtx);
 601                 TAILQ_FOREACH(hc_entry, &V_tcp_hostcache.hashbase[i].hch_bucket,
 602                               rmx_q) {
 603                         len = snprintf(p, linesize,
 604                             "%-15s %5lu %8lu %6lums %6lums %9lu %8lu %8lu %8lu "
 605                             "%4lu %4lu %4i\n",
 606                             hc_entry->ip4.s_addr ? inet_ntoa(hc_entry->ip4) :
 607 #ifdef INET6
 608                                 ip6_sprintf(ip6buf, &hc_entry->ip6),
 609 #else
 610                                 "IPv6?",
 611 #endif
 612                             hc_entry->rmx_mtu,
 613                             hc_entry->rmx_ssthresh,
 614                             msec(hc_entry->rmx_rtt *
 615                                 (RTM_RTTUNIT / (hz * TCP_RTT_SCALE))),
 616                             msec(hc_entry->rmx_rttvar *
 617                                 (RTM_RTTUNIT / (hz * TCP_RTT_SCALE))),
 618                             hc_entry->rmx_bandwidth * 8,
 619                             hc_entry->rmx_cwnd,
 620                             hc_entry->rmx_sendpipe,
 621                             hc_entry->rmx_recvpipe,
 622                             hc_entry->rmx_hits,
 623                             hc_entry->rmx_updates,
 624                             hc_entry->rmx_expire);
 625                         p += len;
 626                 }
 627                 THC_UNLOCK(&V_tcp_hostcache.hashbase[i].hch_mtx);
 628         }
 629 #undef msec
 630         error = SYSCTL_OUT(req, buf, p - buf);
 631         free(buf, M_TEMP);
 632         return(error);
 633 }
 634
 635 /*
 636  * Expire and purge (old|all) entries in the tcp_hostcache.  Runs
 637  * periodically from the callout.
 638  */
 639 static void
 640 tcp_hc_purge(void *arg)
 641 {
 642         CURVNET_SET((struct vnet *) arg);
 643         struct hc_metrics *hc_entry, *hc_next;
 644         int all = 0;
 645         int i;
 646
 647         if (V_tcp_hostcache.purgeall) {
 648                 all = 1;
 649                 V_tcp_hostcache.purgeall = 0;
 650         }
 651
 652         for (i = 0; i < V_tcp_hostcache.hashsize; i++) {
 653                 THC_LOCK(&V_tcp_hostcache.hashbase[i].hch_mtx);
 654                 TAILQ_FOREACH_SAFE(hc_entry,
 655                     &V_tcp_hostcache.hashbase[i].hch_bucket, rmx_q, hc_next) {
 656                         if (all || hc_entry->rmx_expire <= 0) {
 657                                 TAILQ_REMOVE(&V_tcp_hostcache.hashbase[i].hch_bucket,
 658                                               hc_entry, rmx_q);
 659                                 uma_zfree(V_tcp_hostcache.zone, hc_entry);
 660                                 V_tcp_hostcache.hashbase[i].hch_length--;
 661                                 V_tcp_hostcache.cache_count--;
 662                         } else
 663                                 hc_entry->rmx_expire -= V_tcp_hostcache.prune;
 664                 }
 665                 THC_UNLOCK(&V_tcp_hostcache.hashbase[i].hch_mtx);
 666         }
 667
 668         callout_reset(&V_tcp_hc_callout, V_tcp_hostcache.prune * hz,
 669             tcp_hc_purge, arg);
 670         CURVNET_RESTORE();
 671 }