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 #define V_tcp_hostcache         VNET(tcp_hostcache)
 111
 112 static VNET_DEFINE(struct callout, tcp_hc_callout);
 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_internal(int);
 119 static void tcp_hc_purge(void *);
 120
 121 SYSCTL_NODE(_net_inet_tcp, OID_AUTO, hostcache, CTLFLAG_RW, 0,
 122     "TCP Host cache");
 123
 124 SYSCTL_VNET_INT(_net_inet_tcp_hostcache, OID_AUTO, cachelimit, CTLFLAG_RDTUN,
 125     &VNET_NAME(tcp_hostcache.cache_limit), 0,
 126     "Overall entry limit for hostcache");
 127
 128 SYSCTL_VNET_INT(_net_inet_tcp_hostcache, OID_AUTO, hashsize, CTLFLAG_RDTUN,
 129     &VNET_NAME(tcp_hostcache.hashsize), 0,
 130     "Size of TCP hostcache hashtable");
 131
 132 SYSCTL_VNET_INT(_net_inet_tcp_hostcache, OID_AUTO, bucketlimit,
 133     CTLFLAG_RDTUN, &VNET_NAME(tcp_hostcache.bucket_limit), 0,
 134     "Per-bucket hash limit for hostcache");
 135
 136 SYSCTL_VNET_INT(_net_inet_tcp_hostcache, OID_AUTO, count, CTLFLAG_RD,
 137      &VNET_NAME(tcp_hostcache.cache_count), 0,
 138     "Current number of entries in hostcache");
 139
 140 SYSCTL_VNET_INT(_net_inet_tcp_hostcache, OID_AUTO, expire, CTLFLAG_RW,
 141     &VNET_NAME(tcp_hostcache.expire), 0,
 142     "Expire time of TCP hostcache entries");
 143
 144 SYSCTL_VNET_INT(_net_inet_tcp_hostcache, OID_AUTO, prune, CTLFLAG_RW,
 145     &VNET_NAME(tcp_hostcache.prune), 0,
 146     "Time between purge runs");
 147
 148 SYSCTL_VNET_INT(_net_inet_tcp_hostcache, OID_AUTO, purge, CTLFLAG_RW,
 149     &VNET_NAME(tcp_hostcache.purgeall), 0,
 150     "Expire all entires on next purge run");
 151
 152 SYSCTL_PROC(_net_inet_tcp_hostcache, OID_AUTO, list,
 153     CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_SKIP, 0, 0,
 154     sysctl_tcp_hc_list, "A", "List of all hostcache entries");
 155
 156
 157 static MALLOC_DEFINE(M_HOSTCACHE, "hostcache", "TCP hostcache");
 158
 159 #define HOSTCACHE_HASH(ip) \
 160         (((ip)->s_addr ^ ((ip)->s_addr >> 7) ^ ((ip)->s_addr >> 17)) &  \
 161           V_tcp_hostcache.hashmask)
 162
 163 /* XXX: What is the recommended hash to get good entropy for IPv6 addresses? */
 164 #define HOSTCACHE_HASH6(ip6)                            \
 165         (((ip6)->s6_addr32[0] ^                         \
 166           (ip6)->s6_addr32[1] ^                         \
 167           (ip6)->s6_addr32[2] ^                         \
 168           (ip6)->s6_addr32[3]) &                        \
 169          V_tcp_hostcache.hashmask)
 170
 171 #define THC_LOCK(lp)            mtx_lock(lp)
 172 #define THC_UNLOCK(lp)          mtx_unlock(lp)
 173
 174 void
 175 tcp_hc_init(void)
 176 {
 177         int i;
 178
 179         /*
 180          * Initialize hostcache structures.
 181          */
 182         V_tcp_hostcache.cache_count = 0;
 183         V_tcp_hostcache.hashsize = TCP_HOSTCACHE_HASHSIZE;
 184         V_tcp_hostcache.bucket_limit = TCP_HOSTCACHE_BUCKETLIMIT;
 185         V_tcp_hostcache.cache_limit =
 186             V_tcp_hostcache.hashsize * V_tcp_hostcache.bucket_limit;
 187         V_tcp_hostcache.expire = TCP_HOSTCACHE_EXPIRE;
 188         V_tcp_hostcache.prune = TCP_HOSTCACHE_PRUNE;
 189
 190         TUNABLE_INT_FETCH("net.inet.tcp.hostcache.hashsize",
 191             &V_tcp_hostcache.hashsize);
 192         TUNABLE_INT_FETCH("net.inet.tcp.hostcache.cachelimit",
 193             &V_tcp_hostcache.cache_limit);
 194         TUNABLE_INT_FETCH("net.inet.tcp.hostcache.bucketlimit",
 195             &V_tcp_hostcache.bucket_limit);
 196         if (!powerof2(V_tcp_hostcache.hashsize)) {
 197                 printf("WARNING: hostcache hash size is not a power of 2.\n");
 198                 V_tcp_hostcache.hashsize = TCP_HOSTCACHE_HASHSIZE; /* default */
 199         }
 200         V_tcp_hostcache.hashmask = V_tcp_hostcache.hashsize - 1;
 201
 202         /*
 203          * Allocate the hash table.
 204          */
 205         V_tcp_hostcache.hashbase = (struct hc_head *)
 206             malloc(V_tcp_hostcache.hashsize * sizeof(struct hc_head),
 207                    M_HOSTCACHE, M_WAITOK | M_ZERO);
 208
 209         /*
 210          * Initialize the hash buckets.
 211          */
 212         for (i = 0; i < V_tcp_hostcache.hashsize; i++) {
 213                 TAILQ_INIT(&V_tcp_hostcache.hashbase[i].hch_bucket);
 214                 V_tcp_hostcache.hashbase[i].hch_length = 0;
 215                 mtx_init(&V_tcp_hostcache.hashbase[i].hch_mtx, "tcp_hc_entry",
 216                           NULL, MTX_DEF);
 217         }
 218
 219         /*
 220          * Allocate the hostcache entries.
 221          */
 222         V_tcp_hostcache.zone =
 223             uma_zcreate("hostcache", sizeof(struct hc_metrics),
 224             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
 225         uma_zone_set_max(V_tcp_hostcache.zone, V_tcp_hostcache.cache_limit);
 226
 227         /*
 228          * Set up periodic cache cleanup.
 229          */
 230         callout_init(&V_tcp_hc_callout, CALLOUT_MPSAFE);
 231         callout_reset(&V_tcp_hc_callout, V_tcp_hostcache.prune * hz,
 232             tcp_hc_purge, curvnet);
 233 }
 234
 235 #ifdef VIMAGE
 236 void
 237 tcp_hc_destroy(void)
 238 {
 239         int i;
 240
 241         callout_drain(&V_tcp_hc_callout);
 242
 243         /* Purge all hc entries. */
 244         tcp_hc_purge_internal(1);
 245
 246         /* Free the uma zone and the allocated hash table. */
 247         uma_zdestroy(V_tcp_hostcache.zone);
 248
 249         for (i = 0; i < V_tcp_hostcache.hashsize; i++)
 250                 mtx_destroy(&V_tcp_hostcache.hashbase[i].hch_mtx);
 251         free(V_tcp_hostcache.hashbase, M_HOSTCACHE);
 252 }
 253 #endif
 254
 255 /*
 256  * Internal function: look up an entry in the hostcache or return NULL.
 257  *
 258  * If an entry has been returned, the caller becomes responsible for
 259  * unlocking the bucket row after he is done reading/modifying the entry.
 260  */
 261 static struct hc_metrics *
 262 tcp_hc_lookup(struct in_conninfo *inc)
 263 {
 264         int hash;
 265         struct hc_head *hc_head;
 266         struct hc_metrics *hc_entry;
 267
 268         KASSERT(inc != NULL, ("tcp_hc_lookup with NULL in_conninfo pointer"));
 269
 270         /*
 271          * Hash the foreign ip address.
 272          */
 273         if (inc->inc_flags & INC_ISIPV6)
 274                 hash = HOSTCACHE_HASH6(&inc->inc6_faddr);
 275         else
 276                 hash = HOSTCACHE_HASH(&inc->inc_faddr);
 277
 278         hc_head = &V_tcp_hostcache.hashbase[hash];
 279
 280         /*
 281          * Acquire lock for this bucket row; we release the lock if we don't
 282          * find an entry, otherwise the caller has to unlock after he is
 283          * done.
 284          */
 285         THC_LOCK(&hc_head->hch_mtx);
 286
 287         /*
 288          * Iterate through entries in bucket row looking for a match.
 289          */
 290         TAILQ_FOREACH(hc_entry, &hc_head->hch_bucket, rmx_q) {
 291                 if (inc->inc_flags & INC_ISIPV6) {
 292                         if (memcmp(&inc->inc6_faddr, &hc_entry->ip6,
 293                             sizeof(inc->inc6_faddr)) == 0)
 294                                 return hc_entry;
 295                 } else {
 296                         if (memcmp(&inc->inc_faddr, &hc_entry->ip4,
 297                             sizeof(inc->inc_faddr)) == 0)
 298                                 return hc_entry;
 299                 }
 300         }
 301
 302         /*
 303          * We were unsuccessful and didn't find anything.
 304          */
 305         THC_UNLOCK(&hc_head->hch_mtx);
 306         return NULL;
 307 }
 308
 309 /*
 310  * Internal function: insert an entry into the hostcache or return NULL if
 311  * unable to allocate a new one.
 312  *
 313  * If an entry has been returned, the caller becomes responsible for
 314  * unlocking the bucket row after he is done reading/modifying the entry.
 315  */
 316 static struct hc_metrics *
 317 tcp_hc_insert(struct in_conninfo *inc)
 318 {
 319         int hash;
 320         struct hc_head *hc_head;
 321         struct hc_metrics *hc_entry;
 322
 323         KASSERT(inc != NULL, ("tcp_hc_insert with NULL in_conninfo pointer"));
 324
 325         /*
 326          * Hash the foreign ip address.
 327          */
 328         if (inc->inc_flags & INC_ISIPV6)
 329                 hash = HOSTCACHE_HASH6(&inc->inc6_faddr);
 330         else
 331                 hash = HOSTCACHE_HASH(&inc->inc_faddr);
 332
 333         hc_head = &V_tcp_hostcache.hashbase[hash];
 334
 335         /*
 336          * Acquire lock for this bucket row; we release the lock if we don't
 337          * find an entry, otherwise the caller has to unlock after he is
 338          * done.
 339          */
 340         THC_LOCK(&hc_head->hch_mtx);
 341
 342         /*
 343          * If the bucket limit is reached, reuse the least-used element.
 344          */
 345         if (hc_head->hch_length >= V_tcp_hostcache.bucket_limit ||
 346             V_tcp_hostcache.cache_count >= V_tcp_hostcache.cache_limit) {
 347                 hc_entry = TAILQ_LAST(&hc_head->hch_bucket, hc_qhead);
 348                 /*
 349                  * At first we were dropping the last element, just to
 350                  * reacquire it in the next two lines again, which isn't very
 351                  * efficient.  Instead just reuse the least used element.
 352                  * We may drop something that is still "in-use" but we can be
 353                  * "lossy".
 354                  * Just give up if this bucket row is empty and we don't have
 355                  * anything to replace.
 356                  */
 357                 if (hc_entry == NULL) {
 358                         THC_UNLOCK(&hc_head->hch_mtx);
 359                         return NULL;
 360                 }
 361                 TAILQ_REMOVE(&hc_head->hch_bucket, hc_entry, rmx_q);
 362                 V_tcp_hostcache.hashbase[hash].hch_length--;
 363                 V_tcp_hostcache.cache_count--;
 364                 TCPSTAT_INC(tcps_hc_bucketoverflow);
 365 #if 0
 366                 uma_zfree(V_tcp_hostcache.zone, hc_entry);
 367 #endif
 368         } else {
 369                 /*
 370                  * Allocate a new entry, or balk if not possible.
 371                  */
 372                 hc_entry = uma_zalloc(V_tcp_hostcache.zone, M_NOWAIT);
 373                 if (hc_entry == NULL) {
 374                         THC_UNLOCK(&hc_head->hch_mtx);
 375                         return NULL;
 376                 }
 377         }
 378
 379         /*
 380          * Initialize basic information of hostcache entry.
 381          */
 382         bzero(hc_entry, sizeof(*hc_entry));
 383         if (inc->inc_flags & INC_ISIPV6)
 384                 bcopy(&inc->inc6_faddr, &hc_entry->ip6, sizeof(hc_entry->ip6));
 385         else
 386                 hc_entry->ip4 = inc->inc_faddr;
 387         hc_entry->rmx_head = hc_head;
 388         hc_entry->rmx_expire = V_tcp_hostcache.expire;
 389
 390         /*
 391          * Put it upfront.
 392          */
 393         TAILQ_INSERT_HEAD(&hc_head->hch_bucket, hc_entry, rmx_q);
 394         V_tcp_hostcache.hashbase[hash].hch_length++;
 395         V_tcp_hostcache.cache_count++;
 396         TCPSTAT_INC(tcps_hc_added);
 397
 398         return hc_entry;
 399 }
 400
 401 /*
 402  * External function: look up an entry in the hostcache and fill out the
 403  * supplied TCP metrics structure.  Fills in NULL when no entry was found or
 404  * a value is not set.
 405  */
 406 void
 407 tcp_hc_get(struct in_conninfo *inc, struct hc_metrics_lite *hc_metrics_lite)
 408 {
 409         struct hc_metrics *hc_entry;
 410
 411         /*
 412          * Find the right bucket.
 413          */
 414         hc_entry = tcp_hc_lookup(inc);
 415
 416         /*
 417          * If we don't have an existing object.
 418          */
 419         if (hc_entry == NULL) {
 420                 bzero(hc_metrics_lite, sizeof(*hc_metrics_lite));
 421                 return;
 422         }
 423         hc_entry->rmx_hits++;
 424         hc_entry->rmx_expire = V_tcp_hostcache.expire; /* start over again */
 425
 426         hc_metrics_lite->rmx_mtu = hc_entry->rmx_mtu;
 427         hc_metrics_lite->rmx_ssthresh = hc_entry->rmx_ssthresh;
 428         hc_metrics_lite->rmx_rtt = hc_entry->rmx_rtt;
 429         hc_metrics_lite->rmx_rttvar = hc_entry->rmx_rttvar;
 430         hc_metrics_lite->rmx_bandwidth = hc_entry->rmx_bandwidth;
 431         hc_metrics_lite->rmx_cwnd = hc_entry->rmx_cwnd;
 432         hc_metrics_lite->rmx_sendpipe = hc_entry->rmx_sendpipe;
 433         hc_metrics_lite->rmx_recvpipe = hc_entry->rmx_recvpipe;
 434
 435         /*
 436          * Unlock bucket row.
 437          */
 438         THC_UNLOCK(&hc_entry->rmx_head->hch_mtx);
 439 }
 440
 441 /*
 442  * External function: look up an entry in the hostcache and return the
 443  * discovered path MTU.  Returns NULL if no entry is found or value is not
 444  * set.
 445  */
 446 u_long
 447 tcp_hc_getmtu(struct in_conninfo *inc)
 448 {
 449         struct hc_metrics *hc_entry;
 450         u_long mtu;
 451
 452         hc_entry = tcp_hc_lookup(inc);
 453         if (hc_entry == NULL) {
 454                 return 0;
 455         }
 456         hc_entry->rmx_hits++;
 457         hc_entry->rmx_expire = V_tcp_hostcache.expire; /* start over again */
 458
 459         mtu = hc_entry->rmx_mtu;
 460         THC_UNLOCK(&hc_entry->rmx_head->hch_mtx);
 461         return mtu;
 462 }
 463
 464 /*
 465  * External function: update the MTU value of an entry in the hostcache.
 466  * Creates a new entry if none was found.
 467  */
 468 void
 469 tcp_hc_updatemtu(struct in_conninfo *inc, u_long mtu)
 470 {
 471         struct hc_metrics *hc_entry;
 472
 473         /*
 474          * Find the right bucket.
 475          */
 476         hc_entry = tcp_hc_lookup(inc);
 477
 478         /*
 479          * If we don't have an existing object, try to insert a new one.
 480          */
 481         if (hc_entry == NULL) {
 482                 hc_entry = tcp_hc_insert(inc);
 483                 if (hc_entry == NULL)
 484                         return;
 485         }
 486         hc_entry->rmx_updates++;
 487         hc_entry->rmx_expire = V_tcp_hostcache.expire; /* start over again */
 488
 489         hc_entry->rmx_mtu = mtu;
 490
 491         /*
 492          * Put it upfront so we find it faster next time.
 493          */
 494         TAILQ_REMOVE(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q);
 495         TAILQ_INSERT_HEAD(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q);
 496
 497         /*
 498          * Unlock bucket row.
 499          */
 500         THC_UNLOCK(&hc_entry->rmx_head->hch_mtx);
 501 }
 502
 503 /*
 504  * External function: update the TCP metrics of an entry in the hostcache.
 505  * Creates a new entry if none was found.
 506  */
 507 void
 508 tcp_hc_update(struct in_conninfo *inc, struct hc_metrics_lite *hcml)
 509 {
 510         struct hc_metrics *hc_entry;
 511
 512         hc_entry = tcp_hc_lookup(inc);
 513         if (hc_entry == NULL) {
 514                 hc_entry = tcp_hc_insert(inc);
 515                 if (hc_entry == NULL)
 516                         return;
 517         }
 518         hc_entry->rmx_updates++;
 519         hc_entry->rmx_expire = V_tcp_hostcache.expire; /* start over again */
 520
 521         if (hcml->rmx_rtt != 0) {
 522                 if (hc_entry->rmx_rtt == 0)
 523                         hc_entry->rmx_rtt = hcml->rmx_rtt;
 524                 else
 525                         hc_entry->rmx_rtt =
 526                             (hc_entry->rmx_rtt + hcml->rmx_rtt) / 2;
 527                 TCPSTAT_INC(tcps_cachedrtt);
 528         }
 529         if (hcml->rmx_rttvar != 0) {
 530                 if (hc_entry->rmx_rttvar == 0)
 531                         hc_entry->rmx_rttvar = hcml->rmx_rttvar;
 532                 else
 533                         hc_entry->rmx_rttvar =
 534                             (hc_entry->rmx_rttvar + hcml->rmx_rttvar) / 2;
 535                 TCPSTAT_INC(tcps_cachedrttvar);
 536         }
 537         if (hcml->rmx_ssthresh != 0) {
 538                 if (hc_entry->rmx_ssthresh == 0)
 539                         hc_entry->rmx_ssthresh = hcml->rmx_ssthresh;
 540                 else
 541                         hc_entry->rmx_ssthresh =
 542                             (hc_entry->rmx_ssthresh + hcml->rmx_ssthresh) / 2;
 543                 TCPSTAT_INC(tcps_cachedssthresh);
 544         }
 545         if (hcml->rmx_bandwidth != 0) {
 546                 if (hc_entry->rmx_bandwidth == 0)
 547                         hc_entry->rmx_bandwidth = hcml->rmx_bandwidth;
 548                 else
 549                         hc_entry->rmx_bandwidth =
 550                             (hc_entry->rmx_bandwidth + hcml->rmx_bandwidth) / 2;
 551                 /* TCPSTAT_INC(tcps_cachedbandwidth); */
 552         }
 553         if (hcml->rmx_cwnd != 0) {
 554                 if (hc_entry->rmx_cwnd == 0)
 555                         hc_entry->rmx_cwnd = hcml->rmx_cwnd;
 556                 else
 557                         hc_entry->rmx_cwnd =
 558                             (hc_entry->rmx_cwnd + hcml->rmx_cwnd) / 2;
 559                 /* TCPSTAT_INC(tcps_cachedcwnd); */
 560         }
 561         if (hcml->rmx_sendpipe != 0) {
 562                 if (hc_entry->rmx_sendpipe == 0)
 563                         hc_entry->rmx_sendpipe = hcml->rmx_sendpipe;
 564                 else
 565                         hc_entry->rmx_sendpipe =
 566                             (hc_entry->rmx_sendpipe + hcml->rmx_sendpipe) /2;
 567                 /* TCPSTAT_INC(tcps_cachedsendpipe); */
 568         }
 569         if (hcml->rmx_recvpipe != 0) {
 570                 if (hc_entry->rmx_recvpipe == 0)
 571                         hc_entry->rmx_recvpipe = hcml->rmx_recvpipe;
 572                 else
 573                         hc_entry->rmx_recvpipe =
 574                             (hc_entry->rmx_recvpipe + hcml->rmx_recvpipe) /2;
 575                 /* TCPSTAT_INC(tcps_cachedrecvpipe); */
 576         }
 577
 578         TAILQ_REMOVE(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q);
 579         TAILQ_INSERT_HEAD(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q);
 580         THC_UNLOCK(&hc_entry->rmx_head->hch_mtx);
 581 }
 582
 583 /*
 584  * Sysctl function: prints the list and values of all hostcache entries in
 585  * unsorted order.
 586  */
 587 static int
 588 sysctl_tcp_hc_list(SYSCTL_HANDLER_ARGS)
 589 {
 590         int bufsize;
 591         int linesize = 128;
 592         char *p, *buf;
 593         int len, i, error;
 594         struct hc_metrics *hc_entry;
 595 #ifdef INET6
 596         char ip6buf[INET6_ADDRSTRLEN];
 597 #endif
 598
 599         bufsize = linesize * (V_tcp_hostcache.cache_count + 1);
 600
 601         p = buf = (char *)malloc(bufsize, M_TEMP, M_WAITOK|M_ZERO);
 602
 603         len = snprintf(p, linesize,
 604                 "\nIP address        MTU  SSTRESH      RTT   RTTVAR BANDWIDTH "
 605                 "    CWND SENDPIPE RECVPIPE HITS  UPD  EXP\n");
 606         p += len;
 607
 608 #define msec(u) (((u) + 500) / 1000)
 609         for (i = 0; i < V_tcp_hostcache.hashsize; i++) {
 610                 THC_LOCK(&V_tcp_hostcache.hashbase[i].hch_mtx);
 611                 TAILQ_FOREACH(hc_entry, &V_tcp_hostcache.hashbase[i].hch_bucket,
 612                               rmx_q) {
 613                         len = snprintf(p, linesize,
 614                             "%-15s %5lu %8lu %6lums %6lums %9lu %8lu %8lu %8lu "
 615                             "%4lu %4lu %4i\n",
 616                             hc_entry->ip4.s_addr ? inet_ntoa(hc_entry->ip4) :
 617 #ifdef INET6
 618                                 ip6_sprintf(ip6buf, &hc_entry->ip6),
 619 #else
 620                                 "IPv6?",
 621 #endif
 622                             hc_entry->rmx_mtu,
 623                             hc_entry->rmx_ssthresh,
 624                             msec(hc_entry->rmx_rtt *
 625                                 (RTM_RTTUNIT / (hz * TCP_RTT_SCALE))),
 626                             msec(hc_entry->rmx_rttvar *
 627                                 (RTM_RTTUNIT / (hz * TCP_RTT_SCALE))),
 628                             hc_entry->rmx_bandwidth * 8,
 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                         p += len;
 636                 }
 637                 THC_UNLOCK(&V_tcp_hostcache.hashbase[i].hch_mtx);
 638         }
 639 #undef msec
 640         error = SYSCTL_OUT(req, buf, p - buf);
 641         free(buf, M_TEMP);
 642         return(error);
 643 }
 644
 645 /*
 646  * Caller has to make sure the curvnet is set properly.
 647  */
 648 static void
 649 tcp_hc_purge_internal(int all)
 650 {
 651         struct hc_metrics *hc_entry, *hc_next;
 652         int i;
 653
 654         for (i = 0; i < V_tcp_hostcache.hashsize; i++) {
 655                 THC_LOCK(&V_tcp_hostcache.hashbase[i].hch_mtx);
 656                 TAILQ_FOREACH_SAFE(hc_entry,
 657                     &V_tcp_hostcache.hashbase[i].hch_bucket, rmx_q, hc_next) {
 658                         if (all || hc_entry->rmx_expire <= 0) {
 659                                 TAILQ_REMOVE(&V_tcp_hostcache.hashbase[i].hch_bucket,
 660                                               hc_entry, rmx_q);
 661                                 uma_zfree(V_tcp_hostcache.zone, hc_entry);
 662                                 V_tcp_hostcache.hashbase[i].hch_length--;
 663                                 V_tcp_hostcache.cache_count--;
 664                         } else
 665                                 hc_entry->rmx_expire -= V_tcp_hostcache.prune;
 666                 }
 667                 THC_UNLOCK(&V_tcp_hostcache.hashbase[i].hch_mtx);
 668         }
 669 }
 670
 671 /*
 672  * Expire and purge (old|all) entries in the tcp_hostcache.  Runs
 673  * periodically from the callout.
 674  */
 675 static void
 676 tcp_hc_purge(void *arg)
 677 {
 678         CURVNET_SET((struct vnet *) arg);
 679         int all = 0;
 680
 681         if (V_tcp_hostcache.purgeall) {
 682                 all = 1;
 683                 V_tcp_hostcache.purgeall = 0;
 684         }
 685
 686         tcp_hc_purge_internal(all);
 687
 688         callout_reset(&V_tcp_hc_callout, V_tcp_hostcache.prune * hz,
 689             tcp_hc_purge, arg);
 690         CURVNET_RESTORE();
 691 }