sys/netinet/tcp_hostcache.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-3-Clause
   3  *
   4  * Copyright (c) 2002 Andre Oppermann, Internet Business Solutions AG
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. The name of the author may not be used to endorse or promote
  16  *    products derived from this software without specific prior written
  17  *    permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  */
  31
  32 /*
  33  * The tcp_hostcache moves the tcp-specific cached metrics from the routing
  34  * table to a dedicated structure indexed by the remote IP address.  It keeps
  35  * information on the measured TCP parameters of past TCP sessions to allow
  36  * better initial start values to be used with later connections to/from the
  37  * same source.  Depending on the network parameters (delay, max MTU,
  38  * congestion window) between local and remote sites, this can lead to
  39  * significant speed-ups for new TCP connections after the first one.
  40  *
  41  * Due to the tcp_hostcache, all TCP-specific metrics information in the
  42  * routing table have been removed.  The inpcb no longer keeps a pointer to
  43  * the routing entry, and protocol-initiated route cloning has been removed
  44  * as well.  With these changes, the routing table has gone back to being
  45  * more lightwight and only carries information related to packet forwarding.
  46  *
  47  * tcp_hostcache is designed for multiple concurrent access in SMP
  48  * environments and high contention.  All bucket rows have their own lock and
  49  * thus multiple lookups and modifies can be done at the same time as long as
  50  * they are in different bucket rows.  If a request for insertion of a new
  51  * record can't be satisfied, it simply returns an empty structure.  Nobody
  52  * and nothing outside of tcp_hostcache.c will ever point directly to any
  53  * entry in the tcp_hostcache.  All communication is done in an
  54  * object-oriented way and only functions of tcp_hostcache will manipulate
  55  * hostcache entries.  Otherwise, we are unable to achieve good behaviour in
  56  * concurrent access situations.  Since tcp_hostcache is only caching
  57  * information, there are no fatal consequences if we either can't satisfy
  58  * any particular request or have to drop/overwrite an existing entry because
  59  * of bucket limit memory constrains.
  60  */
  61
  62 /*
  63  * Many thanks to jlemon for basic structure of tcp_syncache which is being
  64  * followed here.
  65  */
  66
  67 #include <sys/cdefs.h>
  68 __FBSDID("$FreeBSD$");
  69
  70 #include "opt_inet6.h"
  71
  72 #include <sys/param.h>
  73 #include <sys/systm.h>
  74 #include <sys/jail.h>
  75 #include <sys/kernel.h>
  76 #include <sys/lock.h>
  77 #include <sys/mutex.h>
  78 #include <sys/malloc.h>
  79 #include <sys/proc.h>
  80 #include <sys/sbuf.h>
  81 #include <sys/socket.h>
  82 #include <sys/socketvar.h>
  83 #include <sys/sysctl.h>
  84
  85 #include <net/if.h>
  86 #include <net/if_var.h>
  87 #include <net/route.h>
  88 #include <net/vnet.h>
  89
  90 #include <netinet/in.h>
  91 #include <netinet/in_systm.h>
  92 #include <netinet/ip.h>
  93 #include <netinet/in_var.h>
  94 #include <netinet/in_pcb.h>
  95 #include <netinet/ip_var.h>
  96 #ifdef INET6
  97 #include <netinet/ip6.h>
  98 #include <netinet6/ip6_var.h>
  99 #endif
 100 #include <netinet/tcp.h>
 101 #include <netinet/tcp_var.h>
 102 #include <netinet/tcp_hostcache.h>
 103 #ifdef INET6
 104 #include <netinet6/tcp6_var.h>
 105 #endif
 106
 107 #include <vm/uma.h>
 108
 109 /* Arbitrary values */
 110 #define TCP_HOSTCACHE_HASHSIZE          512
 111 #define TCP_HOSTCACHE_BUCKETLIMIT       30
 112 #define TCP_HOSTCACHE_EXPIRE            60*60   /* one hour */
 113 #define TCP_HOSTCACHE_PRUNE             5*60    /* every 5 minutes */
 114
 115 VNET_DEFINE_STATIC(struct tcp_hostcache, tcp_hostcache);
 116 #define V_tcp_hostcache         VNET(tcp_hostcache)
 117
 118 VNET_DEFINE_STATIC(struct callout, tcp_hc_callout);
 119 #define V_tcp_hc_callout        VNET(tcp_hc_callout)
 120
 121 static struct hc_metrics *tcp_hc_lookup(struct in_conninfo *);
 122 static struct hc_metrics *tcp_hc_insert(struct in_conninfo *);
 123 static int sysctl_tcp_hc_list(SYSCTL_HANDLER_ARGS);
 124 static int sysctl_tcp_hc_purgenow(SYSCTL_HANDLER_ARGS);
 125 static void tcp_hc_purge_internal(int);
 126 static void tcp_hc_purge(void *);
 127
 128 static SYSCTL_NODE(_net_inet_tcp, OID_AUTO, hostcache,
 129     CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
 130     "TCP Host cache");
 131
 132 VNET_DEFINE(int, tcp_use_hostcache) = 1;
 133 #define V_tcp_use_hostcache  VNET(tcp_use_hostcache)
 134 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, enable, CTLFLAG_VNET | CTLFLAG_RW,
 135     &VNET_NAME(tcp_use_hostcache), 0,
 136     "Enable the TCP hostcache");
 137
 138 SYSCTL_UINT(_net_inet_tcp_hostcache, OID_AUTO, cachelimit, CTLFLAG_VNET | CTLFLAG_RDTUN,
 139     &VNET_NAME(tcp_hostcache.cache_limit), 0,
 140     "Overall entry limit for hostcache");
 141
 142 SYSCTL_UINT(_net_inet_tcp_hostcache, OID_AUTO, hashsize, CTLFLAG_VNET | CTLFLAG_RDTUN,
 143     &VNET_NAME(tcp_hostcache.hashsize), 0,
 144     "Size of TCP hostcache hashtable");
 145
 146 SYSCTL_UINT(_net_inet_tcp_hostcache, OID_AUTO, bucketlimit,
 147     CTLFLAG_VNET | CTLFLAG_RDTUN, &VNET_NAME(tcp_hostcache.bucket_limit), 0,
 148     "Per-bucket hash limit for hostcache");
 149
 150 SYSCTL_UINT(_net_inet_tcp_hostcache, OID_AUTO, count, CTLFLAG_VNET | CTLFLAG_RD,
 151      &VNET_NAME(tcp_hostcache.cache_count), 0,
 152     "Current number of entries in hostcache");
 153
 154 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, expire, CTLFLAG_VNET | CTLFLAG_RW,
 155     &VNET_NAME(tcp_hostcache.expire), 0,
 156     "Expire time of TCP hostcache entries");
 157
 158 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, prune, CTLFLAG_VNET | CTLFLAG_RW,
 159     &VNET_NAME(tcp_hostcache.prune), 0,
 160     "Time between purge runs");
 161
 162 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, purge, CTLFLAG_VNET | CTLFLAG_RW,
 163     &VNET_NAME(tcp_hostcache.purgeall), 0,
 164     "Expire all entires on next purge run");
 165
 166 SYSCTL_PROC(_net_inet_tcp_hostcache, OID_AUTO, list,
 167     CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_SKIP | CTLFLAG_MPSAFE,
 168     0, 0, sysctl_tcp_hc_list, "A",
 169     "List of all hostcache entries");
 170
 171 SYSCTL_PROC(_net_inet_tcp_hostcache, OID_AUTO, purgenow,
 172     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE,
 173     NULL, 0, sysctl_tcp_hc_purgenow, "I",
 174     "Immediately purge all entries");
 175
 176 static MALLOC_DEFINE(M_HOSTCACHE, "hostcache", "TCP hostcache");
 177
 178 #define HOSTCACHE_HASH(ip) \
 179         (((ip)->s_addr ^ ((ip)->s_addr >> 7) ^ ((ip)->s_addr >> 17)) &  \
 180           V_tcp_hostcache.hashmask)
 181
 182 /* XXX: What is the recommended hash to get good entropy for IPv6 addresses? */
 183 #define HOSTCACHE_HASH6(ip6)                            \
 184         (((ip6)->s6_addr32[0] ^                         \
 185           (ip6)->s6_addr32[1] ^                         \
 186           (ip6)->s6_addr32[2] ^                         \
 187           (ip6)->s6_addr32[3]) &                        \
 188          V_tcp_hostcache.hashmask)
 189
 190 #define THC_LOCK(lp)            mtx_lock(lp)
 191 #define THC_UNLOCK(lp)          mtx_unlock(lp)
 192
 193 void
 194 tcp_hc_init(void)
 195 {
 196         u_int cache_limit;
 197         int i;
 198
 199         /*
 200          * Initialize hostcache structures.
 201          */
 202         V_tcp_hostcache.cache_count = 0;
 203         V_tcp_hostcache.hashsize = TCP_HOSTCACHE_HASHSIZE;
 204         V_tcp_hostcache.bucket_limit = TCP_HOSTCACHE_BUCKETLIMIT;
 205         V_tcp_hostcache.expire = TCP_HOSTCACHE_EXPIRE;
 206         V_tcp_hostcache.prune = TCP_HOSTCACHE_PRUNE;
 207
 208         TUNABLE_INT_FETCH("net.inet.tcp.hostcache.hashsize",
 209             &V_tcp_hostcache.hashsize);
 210         if (!powerof2(V_tcp_hostcache.hashsize)) {
 211                 printf("WARNING: hostcache hash size is not a power of 2.\n");
 212                 V_tcp_hostcache.hashsize = TCP_HOSTCACHE_HASHSIZE; /* default */
 213         }
 214         V_tcp_hostcache.hashmask = V_tcp_hostcache.hashsize - 1;
 215
 216         TUNABLE_INT_FETCH("net.inet.tcp.hostcache.bucketlimit",
 217             &V_tcp_hostcache.bucket_limit);
 218
 219         cache_limit = V_tcp_hostcache.hashsize * V_tcp_hostcache.bucket_limit;
 220         V_tcp_hostcache.cache_limit = cache_limit;
 221         TUNABLE_INT_FETCH("net.inet.tcp.hostcache.cachelimit",
 222             &V_tcp_hostcache.cache_limit);
 223         if (V_tcp_hostcache.cache_limit > cache_limit)
 224                 V_tcp_hostcache.cache_limit = cache_limit;
 225
 226         /*
 227          * Allocate the hash table.
 228          */
 229         V_tcp_hostcache.hashbase = (struct hc_head *)
 230             malloc(V_tcp_hostcache.hashsize * sizeof(struct hc_head),
 231                    M_HOSTCACHE, M_WAITOK | M_ZERO);
 232
 233         /*
 234          * Initialize the hash buckets.
 235          */
 236         for (i = 0; i < V_tcp_hostcache.hashsize; i++) {
 237                 TAILQ_INIT(&V_tcp_hostcache.hashbase[i].hch_bucket);
 238                 V_tcp_hostcache.hashbase[i].hch_length = 0;
 239                 mtx_init(&V_tcp_hostcache.hashbase[i].hch_mtx, "tcp_hc_entry",
 240                           NULL, MTX_DEF);
 241         }
 242
 243         /*
 244          * Allocate the hostcache entries.
 245          */
 246         V_tcp_hostcache.zone =
 247             uma_zcreate("hostcache", sizeof(struct hc_metrics),
 248             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
 249         uma_zone_set_max(V_tcp_hostcache.zone, V_tcp_hostcache.cache_limit);
 250
 251         /*
 252          * Set up periodic cache cleanup.
 253          */
 254         callout_init(&V_tcp_hc_callout, 1);
 255         callout_reset(&V_tcp_hc_callout, V_tcp_hostcache.prune * hz,
 256             tcp_hc_purge, curvnet);
 257 }
 258
 259 #ifdef VIMAGE
 260 void
 261 tcp_hc_destroy(void)
 262 {
 263         int i;
 264
 265         callout_drain(&V_tcp_hc_callout);
 266
 267         /* Purge all hc entries. */
 268         tcp_hc_purge_internal(1);
 269
 270         /* Free the uma zone and the allocated hash table. */
 271         uma_zdestroy(V_tcp_hostcache.zone);
 272
 273         for (i = 0; i < V_tcp_hostcache.hashsize; i++)
 274                 mtx_destroy(&V_tcp_hostcache.hashbase[i].hch_mtx);
 275         free(V_tcp_hostcache.hashbase, M_HOSTCACHE);
 276 }
 277 #endif
 278
 279 /*
 280  * Internal function: look up an entry in the hostcache or return NULL.
 281  *
 282  * If an entry has been returned, the caller becomes responsible for
 283  * unlocking the bucket row after he is done reading/modifying the entry.
 284  */
 285 static struct hc_metrics *
 286 tcp_hc_lookup(struct in_conninfo *inc)
 287 {
 288         int hash;
 289         struct hc_head *hc_head;
 290         struct hc_metrics *hc_entry;
 291
 292         if (!V_tcp_use_hostcache)
 293                 return NULL;
 294
 295         KASSERT(inc != NULL, ("tcp_hc_lookup with NULL in_conninfo pointer"));
 296
 297         /*
 298          * Hash the foreign ip address.
 299          */
 300         if (inc->inc_flags & INC_ISIPV6)
 301                 hash = HOSTCACHE_HASH6(&inc->inc6_faddr);
 302         else
 303                 hash = HOSTCACHE_HASH(&inc->inc_faddr);
 304
 305         hc_head = &V_tcp_hostcache.hashbase[hash];
 306
 307         /*
 308          * Acquire lock for this bucket row; we release the lock if we don't
 309          * find an entry, otherwise the caller has to unlock after he is
 310          * done.
 311          */
 312         THC_LOCK(&hc_head->hch_mtx);
 313
 314         /*
 315          * Iterate through entries in bucket row looking for a match.
 316          */
 317         TAILQ_FOREACH(hc_entry, &hc_head->hch_bucket, rmx_q) {
 318                 if (inc->inc_flags & INC_ISIPV6) {
 319                         /* XXX: check ip6_zoneid */
 320                         if (memcmp(&inc->inc6_faddr, &hc_entry->ip6,
 321                             sizeof(inc->inc6_faddr)) == 0)
 322                                 return hc_entry;
 323                 } else {
 324                         if (memcmp(&inc->inc_faddr, &hc_entry->ip4,
 325                             sizeof(inc->inc_faddr)) == 0)
 326                                 return hc_entry;
 327                 }
 328         }
 329
 330         /*
 331          * We were unsuccessful and didn't find anything.
 332          */
 333         THC_UNLOCK(&hc_head->hch_mtx);
 334         return NULL;
 335 }
 336
 337 /*
 338  * Internal function: insert an entry into the hostcache or return NULL if
 339  * unable to allocate a new one.
 340  *
 341  * If an entry has been returned, the caller becomes responsible for
 342  * unlocking the bucket row after he is done reading/modifying the entry.
 343  */
 344 static struct hc_metrics *
 345 tcp_hc_insert(struct in_conninfo *inc)
 346 {
 347         int hash;
 348         struct hc_head *hc_head;
 349         struct hc_metrics *hc_entry;
 350
 351         if (!V_tcp_use_hostcache)
 352                 return NULL;
 353
 354         KASSERT(inc != NULL, ("tcp_hc_insert with NULL in_conninfo pointer"));
 355
 356         /*
 357          * Hash the foreign ip address.
 358          */
 359         if (inc->inc_flags & INC_ISIPV6)
 360                 hash = HOSTCACHE_HASH6(&inc->inc6_faddr);
 361         else
 362                 hash = HOSTCACHE_HASH(&inc->inc_faddr);
 363
 364         hc_head = &V_tcp_hostcache.hashbase[hash];
 365
 366         /*
 367          * Acquire lock for this bucket row; we release the lock if we don't
 368          * find an entry, otherwise the caller has to unlock after he is
 369          * done.
 370          */
 371         THC_LOCK(&hc_head->hch_mtx);
 372
 373         /*
 374          * If the bucket limit is reached, reuse the least-used element.
 375          */
 376         if (hc_head->hch_length >= V_tcp_hostcache.bucket_limit ||
 377             V_tcp_hostcache.cache_count >= V_tcp_hostcache.cache_limit) {
 378                 hc_entry = TAILQ_LAST(&hc_head->hch_bucket, hc_qhead);
 379                 /*
 380                  * At first we were dropping the last element, just to
 381                  * reacquire it in the next two lines again, which isn't very
 382                  * efficient.  Instead just reuse the least used element.
 383                  * We may drop something that is still "in-use" but we can be
 384                  * "lossy".
 385                  * Just give up if this bucket row is empty and we don't have
 386                  * anything to replace.
 387                  */
 388                 if (hc_entry == NULL) {
 389                         THC_UNLOCK(&hc_head->hch_mtx);
 390                         return NULL;
 391                 }
 392                 TAILQ_REMOVE(&hc_head->hch_bucket, hc_entry, rmx_q);
 393                 V_tcp_hostcache.hashbase[hash].hch_length--;
 394                 V_tcp_hostcache.cache_count--;
 395                 TCPSTAT_INC(tcps_hc_bucketoverflow);
 396 #if 0
 397                 uma_zfree(V_tcp_hostcache.zone, hc_entry);
 398 #endif
 399         } else {
 400                 /*
 401                  * Allocate a new entry, or balk if not possible.
 402                  */
 403                 hc_entry = uma_zalloc(V_tcp_hostcache.zone, M_NOWAIT);
 404                 if (hc_entry == NULL) {
 405                         THC_UNLOCK(&hc_head->hch_mtx);
 406                         return NULL;
 407                 }
 408         }
 409
 410         /*
 411          * Initialize basic information of hostcache entry.
 412          */
 413         bzero(hc_entry, sizeof(*hc_entry));
 414         if (inc->inc_flags & INC_ISIPV6) {
 415                 hc_entry->ip6 = inc->inc6_faddr;
 416                 hc_entry->ip6_zoneid = inc->inc6_zoneid;
 417         } else
 418                 hc_entry->ip4 = inc->inc_faddr;
 419         hc_entry->rmx_head = hc_head;
 420         hc_entry->rmx_expire = V_tcp_hostcache.expire;
 421
 422         /*
 423          * Put it upfront.
 424          */
 425         TAILQ_INSERT_HEAD(&hc_head->hch_bucket, hc_entry, rmx_q);
 426         V_tcp_hostcache.hashbase[hash].hch_length++;
 427         V_tcp_hostcache.cache_count++;
 428         TCPSTAT_INC(tcps_hc_added);
 429
 430         return hc_entry;
 431 }
 432
 433 /*
 434  * External function: look up an entry in the hostcache and fill out the
 435  * supplied TCP metrics structure.  Fills in NULL when no entry was found or
 436  * a value is not set.
 437  */
 438 void
 439 tcp_hc_get(struct in_conninfo *inc, struct hc_metrics_lite *hc_metrics_lite)
 440 {
 441         struct hc_metrics *hc_entry;
 442
 443         if (!V_tcp_use_hostcache) {
 444                 bzero(hc_metrics_lite, sizeof(*hc_metrics_lite));
 445                 return;
 446         }
 447
 448         /*
 449          * Find the right bucket.
 450          */
 451         hc_entry = tcp_hc_lookup(inc);
 452
 453         /*
 454          * If we don't have an existing object.
 455          */
 456         if (hc_entry == NULL) {
 457                 bzero(hc_metrics_lite, sizeof(*hc_metrics_lite));
 458                 return;
 459         }
 460         hc_entry->rmx_hits++;
 461         hc_entry->rmx_expire = V_tcp_hostcache.expire; /* start over again */
 462
 463         hc_metrics_lite->rmx_mtu = hc_entry->rmx_mtu;
 464         hc_metrics_lite->rmx_ssthresh = hc_entry->rmx_ssthresh;
 465         hc_metrics_lite->rmx_rtt = hc_entry->rmx_rtt;
 466         hc_metrics_lite->rmx_rttvar = hc_entry->rmx_rttvar;
 467         hc_metrics_lite->rmx_cwnd = hc_entry->rmx_cwnd;
 468         hc_metrics_lite->rmx_sendpipe = hc_entry->rmx_sendpipe;
 469         hc_metrics_lite->rmx_recvpipe = hc_entry->rmx_recvpipe;
 470
 471         /*
 472          * Unlock bucket row.
 473          */
 474         THC_UNLOCK(&hc_entry->rmx_head->hch_mtx);
 475 }
 476
 477 /*
 478  * External function: look up an entry in the hostcache and return the
 479  * discovered path MTU.  Returns 0 if no entry is found or value is not
 480  * set.
 481  */
 482 uint32_t
 483 tcp_hc_getmtu(struct in_conninfo *inc)
 484 {
 485         struct hc_metrics *hc_entry;
 486         uint32_t mtu;
 487
 488         if (!V_tcp_use_hostcache)
 489                 return 0;
 490
 491         hc_entry = tcp_hc_lookup(inc);
 492         if (hc_entry == NULL) {
 493                 return 0;
 494         }
 495         hc_entry->rmx_hits++;
 496         hc_entry->rmx_expire = V_tcp_hostcache.expire; /* start over again */
 497
 498         mtu = hc_entry->rmx_mtu;
 499         THC_UNLOCK(&hc_entry->rmx_head->hch_mtx);
 500         return mtu;
 501 }
 502
 503 /*
 504  * External function: update the MTU value of an entry in the hostcache.
 505  * Creates a new entry if none was found.
 506  */
 507 void
 508 tcp_hc_updatemtu(struct in_conninfo *inc, uint32_t mtu)
 509 {
 510         struct hc_metrics *hc_entry;
 511
 512         if (!V_tcp_use_hostcache)
 513                 return;
 514
 515         /*
 516          * Find the right bucket.
 517          */
 518         hc_entry = tcp_hc_lookup(inc);
 519
 520         /*
 521          * If we don't have an existing object, try to insert a new one.
 522          */
 523         if (hc_entry == NULL) {
 524                 hc_entry = tcp_hc_insert(inc);
 525                 if (hc_entry == NULL)
 526                         return;
 527         }
 528         hc_entry->rmx_updates++;
 529         hc_entry->rmx_expire = V_tcp_hostcache.expire; /* start over again */
 530
 531         hc_entry->rmx_mtu = mtu;
 532
 533         /*
 534          * Put it upfront so we find it faster next time.
 535          */
 536         TAILQ_REMOVE(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q);
 537         TAILQ_INSERT_HEAD(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q);
 538
 539         /*
 540          * Unlock bucket row.
 541          */
 542         THC_UNLOCK(&hc_entry->rmx_head->hch_mtx);
 543 }
 544
 545 /*
 546  * External function: update the TCP metrics of an entry in the hostcache.
 547  * Creates a new entry if none was found.
 548  */
 549 void
 550 tcp_hc_update(struct in_conninfo *inc, struct hc_metrics_lite *hcml)
 551 {
 552         struct hc_metrics *hc_entry;
 553
 554         if (!V_tcp_use_hostcache)
 555                 return;
 556
 557         hc_entry = tcp_hc_lookup(inc);
 558         if (hc_entry == NULL) {
 559                 hc_entry = tcp_hc_insert(inc);
 560                 if (hc_entry == NULL)
 561                         return;
 562         }
 563         hc_entry->rmx_updates++;
 564         hc_entry->rmx_expire = V_tcp_hostcache.expire; /* start over again */
 565
 566         if (hcml->rmx_rtt != 0) {
 567                 if (hc_entry->rmx_rtt == 0)
 568                         hc_entry->rmx_rtt = hcml->rmx_rtt;
 569                 else
 570                         hc_entry->rmx_rtt = ((uint64_t)hc_entry->rmx_rtt +
 571                             (uint64_t)hcml->rmx_rtt) / 2;
 572                 TCPSTAT_INC(tcps_cachedrtt);
 573         }
 574         if (hcml->rmx_rttvar != 0) {
 575                 if (hc_entry->rmx_rttvar == 0)
 576                         hc_entry->rmx_rttvar = hcml->rmx_rttvar;
 577                 else
 578                         hc_entry->rmx_rttvar = ((uint64_t)hc_entry->rmx_rttvar +
 579                             (uint64_t)hcml->rmx_rttvar) / 2;
 580                 TCPSTAT_INC(tcps_cachedrttvar);
 581         }
 582         if (hcml->rmx_ssthresh != 0) {
 583                 if (hc_entry->rmx_ssthresh == 0)
 584                         hc_entry->rmx_ssthresh = hcml->rmx_ssthresh;
 585                 else
 586                         hc_entry->rmx_ssthresh =
 587                             (hc_entry->rmx_ssthresh + hcml->rmx_ssthresh) / 2;
 588                 TCPSTAT_INC(tcps_cachedssthresh);
 589         }
 590         if (hcml->rmx_cwnd != 0) {
 591                 if (hc_entry->rmx_cwnd == 0)
 592                         hc_entry->rmx_cwnd = hcml->rmx_cwnd;
 593                 else
 594                         hc_entry->rmx_cwnd = ((uint64_t)hc_entry->rmx_cwnd +
 595                             (uint64_t)hcml->rmx_cwnd) / 2;
 596                 /* TCPSTAT_INC(tcps_cachedcwnd); */
 597         }
 598         if (hcml->rmx_sendpipe != 0) {
 599                 if (hc_entry->rmx_sendpipe == 0)
 600                         hc_entry->rmx_sendpipe = hcml->rmx_sendpipe;
 601                 else
 602                         hc_entry->rmx_sendpipe =
 603                             ((uint64_t)hc_entry->rmx_sendpipe +
 604                             (uint64_t)hcml->rmx_sendpipe) /2;
 605                 /* TCPSTAT_INC(tcps_cachedsendpipe); */
 606         }
 607         if (hcml->rmx_recvpipe != 0) {
 608                 if (hc_entry->rmx_recvpipe == 0)
 609                         hc_entry->rmx_recvpipe = hcml->rmx_recvpipe;
 610                 else
 611                         hc_entry->rmx_recvpipe =
 612                             ((uint64_t)hc_entry->rmx_recvpipe +
 613                             (uint64_t)hcml->rmx_recvpipe) /2;
 614                 /* TCPSTAT_INC(tcps_cachedrecvpipe); */
 615         }
 616
 617         TAILQ_REMOVE(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q);
 618         TAILQ_INSERT_HEAD(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q);
 619         THC_UNLOCK(&hc_entry->rmx_head->hch_mtx);
 620 }
 621
 622 /*
 623  * Sysctl function: prints the list and values of all hostcache entries in
 624  * unsorted order.
 625  */
 626 static int
 627 sysctl_tcp_hc_list(SYSCTL_HANDLER_ARGS)
 628 {
 629         const int linesize = 128;
 630         struct sbuf sb;
 631         int i, error;
 632         struct hc_metrics *hc_entry;
 633         char ip4buf[INET_ADDRSTRLEN];
 634 #ifdef INET6
 635         char ip6buf[INET6_ADDRSTRLEN];
 636 #endif
 637
 638         if (jailed_without_vnet(curthread->td_ucred) != 0)
 639                 return (EPERM);
 640
 641         sbuf_new(&sb, NULL, linesize * (V_tcp_hostcache.cache_count + 1),
 642                 SBUF_INCLUDENUL);
 643
 644         sbuf_printf(&sb,
 645                 "\nIP address        MTU  SSTRESH      RTT   RTTVAR "
 646                 "    CWND SENDPIPE RECVPIPE HITS  UPD  EXP\n");
 647
 648 #define msec(u) (((u) + 500) / 1000)
 649         for (i = 0; i < V_tcp_hostcache.hashsize; i++) {
 650                 THC_LOCK(&V_tcp_hostcache.hashbase[i].hch_mtx);
 651                 TAILQ_FOREACH(hc_entry, &V_tcp_hostcache.hashbase[i].hch_bucket,
 652                               rmx_q) {
 653                         sbuf_printf(&sb,
 654                             "%-15s %5u %8u %6lums %6lums %8u %8u %8u %4lu "
 655                             "%4lu %4i\n",
 656                             hc_entry->ip4.s_addr ?
 657                                 inet_ntoa_r(hc_entry->ip4, ip4buf) :
 658 #ifdef INET6
 659                                 ip6_sprintf(ip6buf, &hc_entry->ip6),
 660 #else
 661                                 "IPv6?",
 662 #endif
 663                             hc_entry->rmx_mtu,
 664                             hc_entry->rmx_ssthresh,
 665                             msec((u_long)hc_entry->rmx_rtt *
 666                                 (RTM_RTTUNIT / (hz * TCP_RTT_SCALE))),
 667                             msec((u_long)hc_entry->rmx_rttvar *
 668                                 (RTM_RTTUNIT / (hz * TCP_RTTVAR_SCALE))),
 669                             hc_entry->rmx_cwnd,
 670                             hc_entry->rmx_sendpipe,
 671                             hc_entry->rmx_recvpipe,
 672                             hc_entry->rmx_hits,
 673                             hc_entry->rmx_updates,
 674                             hc_entry->rmx_expire);
 675                 }
 676                 THC_UNLOCK(&V_tcp_hostcache.hashbase[i].hch_mtx);
 677         }
 678 #undef msec
 679         error = sbuf_finish(&sb);
 680         if (error == 0)
 681                 error = SYSCTL_OUT(req, sbuf_data(&sb), sbuf_len(&sb));
 682         sbuf_delete(&sb);
 683         return(error);
 684 }
 685
 686 /*
 687  * Caller has to make sure the curvnet is set properly.
 688  */
 689 static void
 690 tcp_hc_purge_internal(int all)
 691 {
 692         struct hc_metrics *hc_entry, *hc_next;
 693         int i;
 694
 695         for (i = 0; i < V_tcp_hostcache.hashsize; i++) {
 696                 THC_LOCK(&V_tcp_hostcache.hashbase[i].hch_mtx);
 697                 TAILQ_FOREACH_SAFE(hc_entry,
 698                     &V_tcp_hostcache.hashbase[i].hch_bucket, rmx_q, hc_next) {
 699                         if (all || hc_entry->rmx_expire <= 0) {
 700                                 TAILQ_REMOVE(&V_tcp_hostcache.hashbase[i].hch_bucket,
 701                                               hc_entry, rmx_q);
 702                                 uma_zfree(V_tcp_hostcache.zone, hc_entry);
 703                                 V_tcp_hostcache.hashbase[i].hch_length--;
 704                                 V_tcp_hostcache.cache_count--;
 705                         } else
 706                                 hc_entry->rmx_expire -= V_tcp_hostcache.prune;
 707                 }
 708                 THC_UNLOCK(&V_tcp_hostcache.hashbase[i].hch_mtx);
 709         }
 710 }
 711
 712 /*
 713  * Expire and purge (old|all) entries in the tcp_hostcache.  Runs
 714  * periodically from the callout.
 715  */
 716 static void
 717 tcp_hc_purge(void *arg)
 718 {
 719         CURVNET_SET((struct vnet *) arg);
 720         int all = 0;
 721
 722         if (V_tcp_hostcache.purgeall) {
 723                 all = 1;
 724                 V_tcp_hostcache.purgeall = 0;
 725         }
 726
 727         tcp_hc_purge_internal(all);
 728
 729         callout_reset(&V_tcp_hc_callout, V_tcp_hostcache.prune * hz,
 730             tcp_hc_purge, arg);
 731         CURVNET_RESTORE();
 732 }
 733
 734 /*
 735  * Expire and purge all entries in hostcache immediately.
 736  */
 737 static int
 738 sysctl_tcp_hc_purgenow(SYSCTL_HANDLER_ARGS)
 739 {
 740         int error, val;
 741
 742         val = 0;
 743         error = sysctl_handle_int(oidp, &val, 0, req);
 744         if (error || !req->newptr)
 745                 return (error);
 746
 747         tcp_hc_purge_internal(1);
 748
 749         callout_reset(&V_tcp_hc_callout, V_tcp_hostcache.prune * hz,
 750             tcp_hc_purge, curvnet);
 751
 752         return (0);
 753 }