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, CTLFLAG_RW, 0,
 129     "TCP Host cache");
 130
 131 VNET_DEFINE(int, tcp_use_hostcache) = 1;
 132 #define V_tcp_use_hostcache  VNET(tcp_use_hostcache)
 133 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, enable, CTLFLAG_VNET | CTLFLAG_RW,
 134     &VNET_NAME(tcp_use_hostcache), 0,
 135     "Enable the TCP hostcache");
 136
 137 SYSCTL_UINT(_net_inet_tcp_hostcache, OID_AUTO, cachelimit, CTLFLAG_VNET | CTLFLAG_RDTUN,
 138     &VNET_NAME(tcp_hostcache.cache_limit), 0,
 139     "Overall entry limit for hostcache");
 140
 141 SYSCTL_UINT(_net_inet_tcp_hostcache, OID_AUTO, hashsize, CTLFLAG_VNET | CTLFLAG_RDTUN,
 142     &VNET_NAME(tcp_hostcache.hashsize), 0,
 143     "Size of TCP hostcache hashtable");
 144
 145 SYSCTL_UINT(_net_inet_tcp_hostcache, OID_AUTO, bucketlimit,
 146     CTLFLAG_VNET | CTLFLAG_RDTUN, &VNET_NAME(tcp_hostcache.bucket_limit), 0,
 147     "Per-bucket hash limit for hostcache");
 148
 149 SYSCTL_UINT(_net_inet_tcp_hostcache, OID_AUTO, count, CTLFLAG_VNET | CTLFLAG_RD,
 150      &VNET_NAME(tcp_hostcache.cache_count), 0,
 151     "Current number of entries in hostcache");
 152
 153 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, expire, CTLFLAG_VNET | CTLFLAG_RW,
 154     &VNET_NAME(tcp_hostcache.expire), 0,
 155     "Expire time of TCP hostcache entries");
 156
 157 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, prune, CTLFLAG_VNET | CTLFLAG_RW,
 158     &VNET_NAME(tcp_hostcache.prune), 0,
 159     "Time between purge runs");
 160
 161 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, purge, CTLFLAG_VNET | CTLFLAG_RW,
 162     &VNET_NAME(tcp_hostcache.purgeall), 0,
 163     "Expire all entires on next purge run");
 164
 165 SYSCTL_PROC(_net_inet_tcp_hostcache, OID_AUTO, list,
 166     CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_SKIP, 0, 0,
 167     sysctl_tcp_hc_list, "A", "List of all hostcache entries");
 168
 169 SYSCTL_PROC(_net_inet_tcp_hostcache, OID_AUTO, purgenow,
 170     CTLTYPE_INT | CTLFLAG_RW, NULL, 0,
 171     sysctl_tcp_hc_purgenow, "I", "Immediately purge all entries");
 172
 173 static MALLOC_DEFINE(M_HOSTCACHE, "hostcache", "TCP hostcache");
 174
 175 #define HOSTCACHE_HASH(ip) \
 176         (((ip)->s_addr ^ ((ip)->s_addr >> 7) ^ ((ip)->s_addr >> 17)) &  \
 177           V_tcp_hostcache.hashmask)
 178
 179 /* XXX: What is the recommended hash to get good entropy for IPv6 addresses? */
 180 #define HOSTCACHE_HASH6(ip6)                            \
 181         (((ip6)->s6_addr32[0] ^                         \
 182           (ip6)->s6_addr32[1] ^                         \
 183           (ip6)->s6_addr32[2] ^                         \
 184           (ip6)->s6_addr32[3]) &                        \
 185          V_tcp_hostcache.hashmask)
 186
 187 #define THC_LOCK(lp)            mtx_lock(lp)
 188 #define THC_UNLOCK(lp)          mtx_unlock(lp)
 189
 190 void
 191 tcp_hc_init(void)
 192 {
 193         u_int cache_limit;
 194         int i;
 195
 196         /*
 197          * Initialize hostcache structures.
 198          */
 199         atomic_store_int(&V_tcp_hostcache.cache_count, 0);
 200         V_tcp_hostcache.hashsize = TCP_HOSTCACHE_HASHSIZE;
 201         V_tcp_hostcache.bucket_limit = TCP_HOSTCACHE_BUCKETLIMIT;
 202         V_tcp_hostcache.expire = TCP_HOSTCACHE_EXPIRE;
 203         V_tcp_hostcache.prune = TCP_HOSTCACHE_PRUNE;
 204
 205         TUNABLE_INT_FETCH("net.inet.tcp.hostcache.hashsize",
 206             &V_tcp_hostcache.hashsize);
 207         if (!powerof2(V_tcp_hostcache.hashsize)) {
 208                 printf("WARNING: hostcache hash size is not a power of 2.\n");
 209                 V_tcp_hostcache.hashsize = TCP_HOSTCACHE_HASHSIZE; /* default */
 210         }
 211         V_tcp_hostcache.hashmask = V_tcp_hostcache.hashsize - 1;
 212
 213         TUNABLE_INT_FETCH("net.inet.tcp.hostcache.bucketlimit",
 214             &V_tcp_hostcache.bucket_limit);
 215
 216         cache_limit = V_tcp_hostcache.hashsize * V_tcp_hostcache.bucket_limit;
 217         V_tcp_hostcache.cache_limit = cache_limit;
 218         TUNABLE_INT_FETCH("net.inet.tcp.hostcache.cachelimit",
 219             &V_tcp_hostcache.cache_limit);
 220         if (V_tcp_hostcache.cache_limit > cache_limit)
 221                 V_tcp_hostcache.cache_limit = cache_limit;
 222
 223         /*
 224          * Allocate the hash table.
 225          */
 226         V_tcp_hostcache.hashbase = (struct hc_head *)
 227             malloc(V_tcp_hostcache.hashsize * sizeof(struct hc_head),
 228                    M_HOSTCACHE, M_WAITOK | M_ZERO);
 229
 230         /*
 231          * Initialize the hash buckets.
 232          */
 233         for (i = 0; i < V_tcp_hostcache.hashsize; i++) {
 234                 TAILQ_INIT(&V_tcp_hostcache.hashbase[i].hch_bucket);
 235                 V_tcp_hostcache.hashbase[i].hch_length = 0;
 236                 mtx_init(&V_tcp_hostcache.hashbase[i].hch_mtx, "tcp_hc_entry",
 237                           NULL, MTX_DEF);
 238         }
 239
 240         /*
 241          * Allocate the hostcache entries.
 242          */
 243         V_tcp_hostcache.zone =
 244             uma_zcreate("hostcache", sizeof(struct hc_metrics),
 245             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
 246         uma_zone_set_max(V_tcp_hostcache.zone, V_tcp_hostcache.cache_limit);
 247
 248         /*
 249          * Set up periodic cache cleanup.
 250          */
 251         callout_init(&V_tcp_hc_callout, 1);
 252         callout_reset(&V_tcp_hc_callout, V_tcp_hostcache.prune * hz,
 253             tcp_hc_purge, curvnet);
 254 }
 255
 256 #ifdef VIMAGE
 257 void
 258 tcp_hc_destroy(void)
 259 {
 260         int i;
 261
 262         callout_drain(&V_tcp_hc_callout);
 263
 264         /* Purge all hc entries. */
 265         tcp_hc_purge_internal(1);
 266
 267         /* Free the uma zone and the allocated hash table. */
 268         uma_zdestroy(V_tcp_hostcache.zone);
 269
 270         for (i = 0; i < V_tcp_hostcache.hashsize; i++)
 271                 mtx_destroy(&V_tcp_hostcache.hashbase[i].hch_mtx);
 272         free(V_tcp_hostcache.hashbase, M_HOSTCACHE);
 273 }
 274 #endif
 275
 276 /*
 277  * Internal function: look up an entry in the hostcache or return NULL.
 278  *
 279  * If an entry has been returned, the caller becomes responsible for
 280  * unlocking the bucket row after he is done reading/modifying the entry.
 281  */
 282 static struct hc_metrics *
 283 tcp_hc_lookup(struct in_conninfo *inc)
 284 {
 285         int hash;
 286         struct hc_head *hc_head;
 287         struct hc_metrics *hc_entry;
 288
 289         if (!V_tcp_use_hostcache)
 290                 return NULL;
 291
 292         KASSERT(inc != NULL, ("tcp_hc_lookup with NULL in_conninfo pointer"));
 293
 294         /*
 295          * Hash the foreign ip address.
 296          */
 297         if (inc->inc_flags & INC_ISIPV6)
 298                 hash = HOSTCACHE_HASH6(&inc->inc6_faddr);
 299         else
 300                 hash = HOSTCACHE_HASH(&inc->inc_faddr);
 301
 302         hc_head = &V_tcp_hostcache.hashbase[hash];
 303
 304         /*
 305          * Acquire lock for this bucket row; we release the lock if we don't
 306          * find an entry, otherwise the caller has to unlock after he is
 307          * done.
 308          */
 309         THC_LOCK(&hc_head->hch_mtx);
 310
 311         /*
 312          * Iterate through entries in bucket row looking for a match.
 313          */
 314         TAILQ_FOREACH(hc_entry, &hc_head->hch_bucket, rmx_q) {
 315                 if (inc->inc_flags & INC_ISIPV6) {
 316                         /* XXX: check ip6_zoneid */
 317                         if (memcmp(&inc->inc6_faddr, &hc_entry->ip6,
 318                             sizeof(inc->inc6_faddr)) == 0)
 319                                 return hc_entry;
 320                 } else {
 321                         if (memcmp(&inc->inc_faddr, &hc_entry->ip4,
 322                             sizeof(inc->inc_faddr)) == 0)
 323                                 return hc_entry;
 324                 }
 325         }
 326
 327         /*
 328          * We were unsuccessful and didn't find anything.
 329          */
 330         THC_UNLOCK(&hc_head->hch_mtx);
 331         return NULL;
 332 }
 333
 334 /*
 335  * Internal function: insert an entry into the hostcache or return NULL if
 336  * unable to allocate a new one.
 337  *
 338  * If an entry has been returned, the caller becomes responsible for
 339  * unlocking the bucket row after he is done reading/modifying the entry.
 340  */
 341 static struct hc_metrics *
 342 tcp_hc_insert(struct in_conninfo *inc)
 343 {
 344         int hash;
 345         struct hc_head *hc_head;
 346         struct hc_metrics *hc_entry;
 347
 348         if (!V_tcp_use_hostcache)
 349                 return NULL;
 350
 351         KASSERT(inc != NULL, ("tcp_hc_insert with NULL in_conninfo pointer"));
 352
 353         /*
 354          * Hash the foreign ip address.
 355          */
 356         if (inc->inc_flags & INC_ISIPV6)
 357                 hash = HOSTCACHE_HASH6(&inc->inc6_faddr);
 358         else
 359                 hash = HOSTCACHE_HASH(&inc->inc_faddr);
 360
 361         hc_head = &V_tcp_hostcache.hashbase[hash];
 362
 363         /*
 364          * Acquire lock for this bucket row; we release the lock if we don't
 365          * find an entry, otherwise the caller has to unlock after he is
 366          * done.
 367          */
 368         THC_LOCK(&hc_head->hch_mtx);
 369
 370         /*
 371          * If the bucket limit is reached, reuse the least-used element.
 372          */
 373         if (hc_head->hch_length >= V_tcp_hostcache.bucket_limit ||
 374             atomic_load_int(&V_tcp_hostcache.cache_count) >= V_tcp_hostcache.cache_limit) {
 375                 hc_entry = TAILQ_LAST(&hc_head->hch_bucket, hc_qhead);
 376                 /*
 377                  * At first we were dropping the last element, just to
 378                  * reacquire it in the next two lines again, which isn't very
 379                  * efficient.  Instead just reuse the least used element.
 380                  * We may drop something that is still "in-use" but we can be
 381                  * "lossy".
 382                  * Just give up if this bucket row is empty and we don't have
 383                  * anything to replace.
 384                  */
 385                 if (hc_entry == NULL) {
 386                         THC_UNLOCK(&hc_head->hch_mtx);
 387                         return NULL;
 388                 }
 389                 TAILQ_REMOVE(&hc_head->hch_bucket, hc_entry, rmx_q);
 390                 V_tcp_hostcache.hashbase[hash].hch_length--;
 391                 atomic_subtract_int(&V_tcp_hostcache.cache_count, 1);
 392                 TCPSTAT_INC(tcps_hc_bucketoverflow);
 393 #if 0
 394                 uma_zfree(V_tcp_hostcache.zone, hc_entry);
 395 #endif
 396         } else {
 397                 /*
 398                  * Allocate a new entry, or balk if not possible.
 399                  */
 400                 hc_entry = uma_zalloc(V_tcp_hostcache.zone, M_NOWAIT);
 401                 if (hc_entry == NULL) {
 402                         THC_UNLOCK(&hc_head->hch_mtx);
 403                         return NULL;
 404                 }
 405         }
 406
 407         /*
 408          * Initialize basic information of hostcache entry.
 409          */
 410         bzero(hc_entry, sizeof(*hc_entry));
 411         if (inc->inc_flags & INC_ISIPV6) {
 412                 hc_entry->ip6 = inc->inc6_faddr;
 413                 hc_entry->ip6_zoneid = inc->inc6_zoneid;
 414         } else
 415                 hc_entry->ip4 = inc->inc_faddr;
 416         hc_entry->rmx_head = hc_head;
 417         hc_entry->rmx_expire = V_tcp_hostcache.expire;
 418
 419         /*
 420          * Put it upfront.
 421          */
 422         TAILQ_INSERT_HEAD(&hc_head->hch_bucket, hc_entry, rmx_q);
 423         V_tcp_hostcache.hashbase[hash].hch_length++;
 424         atomic_add_int(&V_tcp_hostcache.cache_count, 1);
 425         TCPSTAT_INC(tcps_hc_added);
 426
 427         return hc_entry;
 428 }
 429
 430 /*
 431  * External function: look up an entry in the hostcache and fill out the
 432  * supplied TCP metrics structure.  Fills in NULL when no entry was found or
 433  * a value is not set.
 434  */
 435 void
 436 tcp_hc_get(struct in_conninfo *inc, struct hc_metrics_lite *hc_metrics_lite)
 437 {
 438         struct hc_metrics *hc_entry;
 439
 440         if (!V_tcp_use_hostcache) {
 441                 bzero(hc_metrics_lite, sizeof(*hc_metrics_lite));
 442                 return;
 443         }
 444
 445         /*
 446          * Find the right bucket.
 447          */
 448         hc_entry = tcp_hc_lookup(inc);
 449
 450         /*
 451          * If we don't have an existing object.
 452          */
 453         if (hc_entry == NULL) {
 454                 bzero(hc_metrics_lite, sizeof(*hc_metrics_lite));
 455                 return;
 456         }
 457         hc_entry->rmx_hits++;
 458         hc_entry->rmx_expire = V_tcp_hostcache.expire; /* start over again */
 459
 460         hc_metrics_lite->rmx_mtu = hc_entry->rmx_mtu;
 461         hc_metrics_lite->rmx_ssthresh = hc_entry->rmx_ssthresh;
 462         hc_metrics_lite->rmx_rtt = hc_entry->rmx_rtt;
 463         hc_metrics_lite->rmx_rttvar = hc_entry->rmx_rttvar;
 464         hc_metrics_lite->rmx_cwnd = hc_entry->rmx_cwnd;
 465         hc_metrics_lite->rmx_sendpipe = hc_entry->rmx_sendpipe;
 466         hc_metrics_lite->rmx_recvpipe = hc_entry->rmx_recvpipe;
 467
 468         /*
 469          * Unlock bucket row.
 470          */
 471         THC_UNLOCK(&hc_entry->rmx_head->hch_mtx);
 472 }
 473
 474 /*
 475  * External function: look up an entry in the hostcache and return the
 476  * discovered path MTU.  Returns 0 if no entry is found or value is not
 477  * set.
 478  */
 479 uint32_t
 480 tcp_hc_getmtu(struct in_conninfo *inc)
 481 {
 482         struct hc_metrics *hc_entry;
 483         uint32_t mtu;
 484
 485         if (!V_tcp_use_hostcache)
 486                 return 0;
 487
 488         hc_entry = tcp_hc_lookup(inc);
 489         if (hc_entry == NULL) {
 490                 return 0;
 491         }
 492         hc_entry->rmx_hits++;
 493         hc_entry->rmx_expire = V_tcp_hostcache.expire; /* start over again */
 494
 495         mtu = hc_entry->rmx_mtu;
 496         THC_UNLOCK(&hc_entry->rmx_head->hch_mtx);
 497         return mtu;
 498 }
 499
 500 /*
 501  * External function: update the MTU value of an entry in the hostcache.
 502  * Creates a new entry if none was found.
 503  */
 504 void
 505 tcp_hc_updatemtu(struct in_conninfo *inc, uint32_t mtu)
 506 {
 507         struct hc_metrics *hc_entry;
 508
 509         if (!V_tcp_use_hostcache)
 510                 return;
 511
 512         /*
 513          * Find the right bucket.
 514          */
 515         hc_entry = tcp_hc_lookup(inc);
 516
 517         /*
 518          * If we don't have an existing object, try to insert a new one.
 519          */
 520         if (hc_entry == NULL) {
 521                 hc_entry = tcp_hc_insert(inc);
 522                 if (hc_entry == NULL)
 523                         return;
 524         }
 525         hc_entry->rmx_updates++;
 526         hc_entry->rmx_expire = V_tcp_hostcache.expire; /* start over again */
 527
 528         hc_entry->rmx_mtu = mtu;
 529
 530         /*
 531          * Put it upfront so we find it faster next time.
 532          */
 533         TAILQ_REMOVE(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q);
 534         TAILQ_INSERT_HEAD(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q);
 535
 536         /*
 537          * Unlock bucket row.
 538          */
 539         THC_UNLOCK(&hc_entry->rmx_head->hch_mtx);
 540 }
 541
 542 /*
 543  * External function: update the TCP metrics of an entry in the hostcache.
 544  * Creates a new entry if none was found.
 545  */
 546 void
 547 tcp_hc_update(struct in_conninfo *inc, struct hc_metrics_lite *hcml)
 548 {
 549         struct hc_metrics *hc_entry;
 550
 551         if (!V_tcp_use_hostcache)
 552                 return;
 553
 554         hc_entry = tcp_hc_lookup(inc);
 555         if (hc_entry == NULL) {
 556                 hc_entry = tcp_hc_insert(inc);
 557                 if (hc_entry == NULL)
 558                         return;
 559         }
 560         hc_entry->rmx_updates++;
 561         hc_entry->rmx_expire = V_tcp_hostcache.expire; /* start over again */
 562
 563         if (hcml->rmx_rtt != 0) {
 564                 if (hc_entry->rmx_rtt == 0)
 565                         hc_entry->rmx_rtt = hcml->rmx_rtt;
 566                 else
 567                         hc_entry->rmx_rtt = ((uint64_t)hc_entry->rmx_rtt +
 568                             (uint64_t)hcml->rmx_rtt) / 2;
 569                 TCPSTAT_INC(tcps_cachedrtt);
 570         }
 571         if (hcml->rmx_rttvar != 0) {
 572                 if (hc_entry->rmx_rttvar == 0)
 573                         hc_entry->rmx_rttvar = hcml->rmx_rttvar;
 574                 else
 575                         hc_entry->rmx_rttvar = ((uint64_t)hc_entry->rmx_rttvar +
 576                             (uint64_t)hcml->rmx_rttvar) / 2;
 577                 TCPSTAT_INC(tcps_cachedrttvar);
 578         }
 579         if (hcml->rmx_ssthresh != 0) {
 580                 if (hc_entry->rmx_ssthresh == 0)
 581                         hc_entry->rmx_ssthresh = hcml->rmx_ssthresh;
 582                 else
 583                         hc_entry->rmx_ssthresh =
 584                             (hc_entry->rmx_ssthresh + hcml->rmx_ssthresh) / 2;
 585                 TCPSTAT_INC(tcps_cachedssthresh);
 586         }
 587         if (hcml->rmx_cwnd != 0) {
 588                 if (hc_entry->rmx_cwnd == 0)
 589                         hc_entry->rmx_cwnd = hcml->rmx_cwnd;
 590                 else
 591                         hc_entry->rmx_cwnd = ((uint64_t)hc_entry->rmx_cwnd +
 592                             (uint64_t)hcml->rmx_cwnd) / 2;
 593                 /* TCPSTAT_INC(tcps_cachedcwnd); */
 594         }
 595         if (hcml->rmx_sendpipe != 0) {
 596                 if (hc_entry->rmx_sendpipe == 0)
 597                         hc_entry->rmx_sendpipe = hcml->rmx_sendpipe;
 598                 else
 599                         hc_entry->rmx_sendpipe =
 600                             ((uint64_t)hc_entry->rmx_sendpipe +
 601                             (uint64_t)hcml->rmx_sendpipe) /2;
 602                 /* TCPSTAT_INC(tcps_cachedsendpipe); */
 603         }
 604         if (hcml->rmx_recvpipe != 0) {
 605                 if (hc_entry->rmx_recvpipe == 0)
 606                         hc_entry->rmx_recvpipe = hcml->rmx_recvpipe;
 607                 else
 608                         hc_entry->rmx_recvpipe =
 609                             ((uint64_t)hc_entry->rmx_recvpipe +
 610                             (uint64_t)hcml->rmx_recvpipe) /2;
 611                 /* TCPSTAT_INC(tcps_cachedrecvpipe); */
 612         }
 613
 614         TAILQ_REMOVE(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q);
 615         TAILQ_INSERT_HEAD(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q);
 616         THC_UNLOCK(&hc_entry->rmx_head->hch_mtx);
 617 }
 618
 619 /*
 620  * Sysctl function: prints the list and values of all hostcache entries in
 621  * unsorted order.
 622  */
 623 static int
 624 sysctl_tcp_hc_list(SYSCTL_HANDLER_ARGS)
 625 {
 626         const int linesize = 128;
 627         struct sbuf sb;
 628         int i, error, len;
 629         struct hc_metrics *hc_entry;
 630         char ip4buf[INET_ADDRSTRLEN];
 631 #ifdef INET6
 632         char ip6buf[INET6_ADDRSTRLEN];
 633 #endif
 634
 635         if (jailed_without_vnet(curthread->td_ucred) != 0)
 636                 return (EPERM);
 637
 638         /* Optimize Buffer length query by sbin/sysctl */
 639         if (req->oldptr == NULL) {
 640                 len = (atomic_load_int(&V_tcp_hostcache.cache_count) + 1) *
 641                         linesize;
 642                 return (SYSCTL_OUT(req, NULL, len));
 643         }
 644
 645         error = sysctl_wire_old_buffer(req, 0);
 646         if (error != 0) {
 647                 return(error);
 648         }
 649
 650         /* Use a buffer sized for one full bucket */
 651         sbuf_new_for_sysctl(&sb, NULL, V_tcp_hostcache.bucket_limit *
 652                 linesize, req);
 653
 654         sbuf_printf(&sb,
 655                 "\nIP address        MTU  SSTRESH      RTT   RTTVAR "
 656                 "    CWND SENDPIPE RECVPIPE HITS  UPD  EXP\n");
 657         sbuf_drain(&sb);
 658
 659 #define msec(u) (((u) + 500) / 1000)
 660         for (i = 0; i < V_tcp_hostcache.hashsize; i++) {
 661                 THC_LOCK(&V_tcp_hostcache.hashbase[i].hch_mtx);
 662                 TAILQ_FOREACH(hc_entry, &V_tcp_hostcache.hashbase[i].hch_bucket,
 663                               rmx_q) {
 664                         sbuf_printf(&sb,
 665                             "%-15s %5u %8u %6lums %6lums %8u %8u %8u %4lu "
 666                             "%4lu %4i\n",
 667                             hc_entry->ip4.s_addr ?
 668                                 inet_ntoa_r(hc_entry->ip4, ip4buf) :
 669 #ifdef INET6
 670                                 ip6_sprintf(ip6buf, &hc_entry->ip6),
 671 #else
 672                                 "IPv6?",
 673 #endif
 674                             hc_entry->rmx_mtu,
 675                             hc_entry->rmx_ssthresh,
 676                             msec((u_long)hc_entry->rmx_rtt *
 677                                 (RTM_RTTUNIT / (hz * TCP_RTT_SCALE))),
 678                             msec((u_long)hc_entry->rmx_rttvar *
 679                                 (RTM_RTTUNIT / (hz * TCP_RTTVAR_SCALE))),
 680                             hc_entry->rmx_cwnd,
 681                             hc_entry->rmx_sendpipe,
 682                             hc_entry->rmx_recvpipe,
 683                             hc_entry->rmx_hits,
 684                             hc_entry->rmx_updates,
 685                             hc_entry->rmx_expire);
 686                 }
 687                 THC_UNLOCK(&V_tcp_hostcache.hashbase[i].hch_mtx);
 688                 sbuf_drain(&sb);
 689         }
 690 #undef msec
 691         error = sbuf_finish(&sb);
 692         sbuf_delete(&sb);
 693         return(error);
 694 }
 695
 696 /*
 697  * Caller has to make sure the curvnet is set properly.
 698  */
 699 static void
 700 tcp_hc_purge_internal(int all)
 701 {
 702         struct hc_metrics *hc_entry, *hc_next;
 703         int i;
 704
 705         for (i = 0; i < V_tcp_hostcache.hashsize; i++) {
 706                 THC_LOCK(&V_tcp_hostcache.hashbase[i].hch_mtx);
 707                 TAILQ_FOREACH_SAFE(hc_entry,
 708                     &V_tcp_hostcache.hashbase[i].hch_bucket, rmx_q, hc_next) {
 709                         if (all || hc_entry->rmx_expire <= 0) {
 710                                 TAILQ_REMOVE(&V_tcp_hostcache.hashbase[i].hch_bucket,
 711                                               hc_entry, rmx_q);
 712                                 uma_zfree(V_tcp_hostcache.zone, hc_entry);
 713                                 V_tcp_hostcache.hashbase[i].hch_length--;
 714                                 atomic_subtract_int(&V_tcp_hostcache.cache_count, 1);
 715                         } else
 716                                 hc_entry->rmx_expire -= V_tcp_hostcache.prune;
 717                 }
 718                 THC_UNLOCK(&V_tcp_hostcache.hashbase[i].hch_mtx);
 719         }
 720 }
 721
 722 /*
 723  * Expire and purge (old|all) entries in the tcp_hostcache.  Runs
 724  * periodically from the callout.
 725  */
 726 static void
 727 tcp_hc_purge(void *arg)
 728 {
 729         CURVNET_SET((struct vnet *) arg);
 730         int all = 0;
 731
 732         if (V_tcp_hostcache.purgeall) {
 733                 all = 1;
 734                 V_tcp_hostcache.purgeall = 0;
 735         }
 736
 737         tcp_hc_purge_internal(all);
 738
 739         callout_reset(&V_tcp_hc_callout, V_tcp_hostcache.prune * hz,
 740             tcp_hc_purge, arg);
 741         CURVNET_RESTORE();
 742 }
 743
 744 /*
 745  * Expire and purge all entries in hostcache immediately.
 746  */
 747 static int
 748 sysctl_tcp_hc_purgenow(SYSCTL_HANDLER_ARGS)
 749 {
 750         int error, val;
 751
 752         val = 0;
 753         error = sysctl_handle_int(oidp, &val, 0, req);
 754         if (error || !req->newptr)
 755                 return (error);
 756
 757         tcp_hc_purge_internal(1);
 758
 759         callout_reset(&V_tcp_hc_callout, V_tcp_hostcache.prune * hz,
 760             tcp_hc_purge, curvnet);
 761
 762         return (0);
 763 }