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  * $FreeBSD$
  30  */
  31
  32 /*
  33  * The tcp_hostcache moves the tcp specific cached metrics from the routing
  34  * table into a dedicated structure indexed by the remote IP address. It
  35  * keeps information on the measured tcp parameters of past tcp sessions
  36  * to have better initial start values for following connections from the
  37  * same source. Depending on the network parameters (delay, bandwidth, max
  38  * MTU, congestion window) between local and remote site this can lead to
  39  * significant speedups for new tcp connections after the first one.
  40  *
  41  * Due to this new tcp_hostcache all tcp specific metrics information in
  42  * the routing table has been removed. The INPCB no longer keeps a pointer
  43  * to the routing entry and protocol initiated route cloning has been
  44  * removed as well. With these changes the routing table has gone back
  45  * to being more lightwight and only carries information related to packet
  46  * forwarding.
  47  *
  48  * Tcp_hostcache is designed for multiple concurrent access in SMP
  49  * environments and high contention. All bucket rows have their own
  50  * lock and thus multiple lookups and modifies can be done at the same
  51  * time as long as they are in different bucket rows. If a request for
  52  * insertion of a new record can't be satisfied it simply returns an
  53  * empty structure. Nobody and nothing shall ever point directly to
  54  * any entry in tcp_hostcache. All communication is done in an object
  55  * oriented way and only funtions of tcp_hostcache will manipulate hostcache
  56  * entries. Otherwise we are unable to achieve good behaviour in concurrent
  57  * access situations. Since tcp_hostcache is only caching information there
  58  * are no fatal consequences if we either can't satisfy any particular request
  59  * or have to drop/overwrite an existing entry because of bucket limit
  60  * memory constrains.
  61  */
  62
  63 /*
  64  * Many thanks to jlemon for basic structure of tcp_syncache which is being
  65  * followed here.
  66  */
  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
  82 #include <netinet/in.h>
  83 #include <netinet/in_systm.h>
  84 #include <netinet/ip.h>
  85 #include <netinet/in_var.h>
  86 #include <netinet/in_pcb.h>
  87 #include <netinet/ip_var.h>
  88 #ifdef INET6
  89 #include <netinet/ip6.h>
  90 #include <netinet6/ip6_var.h>
  91 #endif
  92 #include <netinet/tcp.h>
  93 #include <netinet/tcp_var.h>
  94 #ifdef INET6
  95 #include <netinet6/tcp6_var.h>
  96 #endif
  97
  98 #include <vm/uma.h>
  99
 100
 101 TAILQ_HEAD(hc_qhead, hc_metrics);
 102
 103 struct hc_head {
 104         struct hc_qhead hch_bucket;
 105         u_int           hch_length;
 106         struct mtx      hch_mtx;
 107 };
 108
 109 struct hc_metrics {
 110         /* housekeeping */
 111         TAILQ_ENTRY(hc_metrics) rmx_q;
 112         struct  hc_head *rmx_head; /* head of bucket tail queue */
 113         struct  in_addr ip4;    /* IP address */
 114         struct  in6_addr ip6;   /* IP6 address */
 115         /* endpoint specific values for tcp */
 116         u_long  rmx_mtu;        /* MTU for this path */
 117         u_long  rmx_ssthresh;   /* outbound gateway buffer limit */
 118         u_long  rmx_rtt;        /* estimated round trip time */
 119         u_long  rmx_rttvar;     /* estimated rtt variance */
 120         u_long  rmx_bandwidth;  /* estimated bandwidth */
 121         u_long  rmx_cwnd;       /* congestion window */
 122         u_long  rmx_sendpipe;   /* outbound delay-bandwidth product */
 123         u_long  rmx_recvpipe;   /* inbound delay-bandwidth product */
 124         /* tcp hostcache internal data */
 125         int     rmx_expire;     /* lifetime for object */
 126         u_long  rmx_hits;       /* number of hits */
 127         u_long  rmx_updates;    /* number of updates */
 128 };
 129
 130 /* Arbitrary values */
 131 #define TCP_HOSTCACHE_HASHSIZE          512
 132 #define TCP_HOSTCACHE_BUCKETLIMIT       30
 133 #define TCP_HOSTCACHE_EXPIRE            60*60   /* one hour */
 134 #define TCP_HOSTCACHE_PRUNE             5*60    /* every 5 minutes */
 135
 136 struct tcp_hostcache {
 137         struct  hc_head *hashbase;
 138         uma_zone_t zone;
 139         u_int   hashsize;
 140         u_int   hashmask;
 141         u_int   bucket_limit;
 142         u_int   cache_count;
 143         u_int   cache_limit;
 144         int     expire;
 145         int     purgeall;
 146 };
 147 static struct tcp_hostcache tcp_hostcache;
 148
 149 static struct callout tcp_hc_callout;
 150
 151 static struct hc_metrics *tcp_hc_lookup(struct in_conninfo *);
 152 static struct hc_metrics *tcp_hc_insert(struct in_conninfo *);
 153 static int sysctl_tcp_hc_list(SYSCTL_HANDLER_ARGS);
 154 static void tcp_hc_purge(void *);
 155
 156 SYSCTL_NODE(_net_inet_tcp, OID_AUTO, hostcache, CTLFLAG_RW, 0, "TCP Host cache");
 157
 158 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, cachelimit, CTLFLAG_RDTUN,
 159     &tcp_hostcache.cache_limit, 0, "Overall entry limit for hostcache");
 160
 161 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, hashsize, CTLFLAG_RDTUN,
 162     &tcp_hostcache.hashsize, 0, "Size of TCP hostcache hashtable");
 163
 164 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, bucketlimit, CTLFLAG_RDTUN,
 165     &tcp_hostcache.bucket_limit, 0, "Per-bucket hash limit for hostcache");
 166
 167 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, count, CTLFLAG_RD,
 168     &tcp_hostcache.cache_count, 0, "Current number of entries in hostcache");
 169
 170 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, expire, CTLFLAG_RW,
 171     &tcp_hostcache.expire, 0, "Expire time of TCP hostcache entries");
 172
 173 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, purge, CTLFLAG_RW,
 174     &tcp_hostcache.purgeall, 0, "Expire all entires on next purge run");
 175
 176 SYSCTL_PROC(_net_inet_tcp_hostcache, OID_AUTO, list,
 177     CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_SKIP, 0, 0,
 178     sysctl_tcp_hc_list, "A", "List of all hostcache entries");
 179
 180
 181 static MALLOC_DEFINE(M_HOSTCACHE, "hostcache", "TCP hostcache");
 182
 183 #define HOSTCACHE_HASH(ip) \
 184         (((ip)->s_addr ^ ((ip)->s_addr >> 7) ^ ((ip)->s_addr >> 17)) &  \
 185           tcp_hostcache.hashmask)
 186
 187 /* XXX: What is the recommended hash to get good entropy for IPv6 addresses? */
 188 #define HOSTCACHE_HASH6(ip6)                            \
 189         (((ip6)->s6_addr32[0] ^                         \
 190           (ip6)->s6_addr32[1] ^                         \
 191           (ip6)->s6_addr32[2] ^                         \
 192           (ip6)->s6_addr32[3]) &                        \
 193          tcp_hostcache.hashmask)
 194
 195 #define THC_LOCK(lp)            mtx_lock(lp)
 196 #define THC_UNLOCK(lp)          mtx_unlock(lp)
 197
 198 void
 199 tcp_hc_init(void)
 200 {
 201         int i;
 202
 203         /*
 204          * Initialize hostcache structures
 205          */
 206         tcp_hostcache.cache_count = 0;
 207         tcp_hostcache.hashsize = TCP_HOSTCACHE_HASHSIZE;
 208         tcp_hostcache.bucket_limit = TCP_HOSTCACHE_BUCKETLIMIT;
 209         tcp_hostcache.cache_limit =
 210             tcp_hostcache.hashsize * tcp_hostcache.bucket_limit;
 211         tcp_hostcache.expire = TCP_HOSTCACHE_EXPIRE;
 212
 213         TUNABLE_INT_FETCH("net.inet.tcp.hostcache.hashsize",
 214             &tcp_hostcache.hashsize);
 215         TUNABLE_INT_FETCH("net.inet.tcp.hostcache.cachelimit",
 216             &tcp_hostcache.cache_limit);
 217         TUNABLE_INT_FETCH("net.inet.tcp.hostcache.bucketlimit",
 218             &tcp_hostcache.bucket_limit);
 219         if (!powerof2(tcp_hostcache.hashsize)) {
 220                 printf("WARNING: hostcache hash size is not a power of 2.\n");
 221                 tcp_hostcache.hashsize = 512;   /* safe default */
 222         }
 223         tcp_hostcache.hashmask = tcp_hostcache.hashsize - 1;
 224
 225         /*
 226          * Allocate the hash table
 227          */
 228         tcp_hostcache.hashbase = (struct hc_head *)
 229             malloc(tcp_hostcache.hashsize * sizeof(struct hc_head),
 230                    M_HOSTCACHE, M_WAITOK | M_ZERO);
 231
 232         /*
 233          * Initialize the hash buckets
 234          */
 235         for (i = 0; i < tcp_hostcache.hashsize; i++) {
 236                 TAILQ_INIT(&tcp_hostcache.hashbase[i].hch_bucket);
 237                 tcp_hostcache.hashbase[i].hch_length = 0;
 238                 mtx_init(&tcp_hostcache.hashbase[i].hch_mtx, "tcp_hc_entry",
 239                           NULL, MTX_DEF);
 240         }
 241
 242         /*
 243          * Allocate the hostcache entries.
 244          */
 245         tcp_hostcache.zone = uma_zcreate("hostcache", sizeof(struct hc_metrics),
 246             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
 247         uma_zone_set_max(tcp_hostcache.zone, tcp_hostcache.cache_limit);
 248
 249         /*
 250          * Set up periodic cache cleanup.
 251          */
 252         callout_init(&tcp_hc_callout, CALLOUT_MPSAFE);
 253         callout_reset(&tcp_hc_callout, TCP_HOSTCACHE_PRUNE * hz, tcp_hc_purge, 0);
 254 }
 255
 256 /*
 257  * Internal function: lookup an entry in the hostcache or return NULL.
 258  *
 259  * If an entry has been returned, the caller becomes responsible for
 260  * unlocking the bucket row after he is done reading/modifying the entry.
 261  */
 262 static struct hc_metrics *
 263 tcp_hc_lookup(struct in_conninfo *inc)
 264 {
 265         int hash;
 266         struct hc_head *hc_head;
 267         struct hc_metrics *hc_entry;
 268
 269         KASSERT(inc != NULL, ("tcp_hc_lookup with NULL in_conninfo pointer"));
 270
 271         /*
 272          * Hash the foreign ip address.
 273          */
 274         if (inc->inc_isipv6)
 275                 hash = HOSTCACHE_HASH6(&inc->inc6_faddr);
 276         else
 277                 hash = HOSTCACHE_HASH(&inc->inc_faddr);
 278
 279         hc_head = &tcp_hostcache.hashbase[hash];
 280
 281         /*
 282          * aquire lock for this bucket row
 283          * we release the lock if we don't find an entry,
 284          * otherwise the caller has to unlock after he is done
 285          */
 286         THC_LOCK(&hc_head->hch_mtx);
 287
 288         /*
 289          * circle through entries in bucket row looking for a match
 290          */
 291         TAILQ_FOREACH(hc_entry, &hc_head->hch_bucket, rmx_q) {
 292                 if (inc->inc_isipv6) {
 293                         if (memcmp(&inc->inc6_faddr, &hc_entry->ip6,
 294                             sizeof(inc->inc6_faddr)) == 0)
 295                                 return hc_entry;
 296                 } else {
 297                         if (memcmp(&inc->inc_faddr, &hc_entry->ip4,
 298                             sizeof(inc->inc_faddr)) == 0)
 299                                 return hc_entry;
 300                 }
 301         }
 302
 303         /*
 304          * We were unsuccessful and didn't find anything
 305          */
 306         THC_UNLOCK(&hc_head->hch_mtx);
 307         return NULL;
 308 }
 309
 310 /*
 311  * Internal function: insert an entry into the hostcache or return NULL
 312  * if unable to allocate a new one.
 313  *
 314  * If an entry has been returned, the caller becomes responsible for
 315  * unlocking the bucket row after he is done reading/modifying the entry.
 316  */
 317 static struct hc_metrics *
 318 tcp_hc_insert(struct in_conninfo *inc)
 319 {
 320         int hash;
 321         struct hc_head *hc_head;
 322         struct hc_metrics *hc_entry;
 323
 324         KASSERT(inc != NULL, ("tcp_hc_insert with NULL in_conninfo pointer"));
 325
 326         /*
 327          * Hash the foreign ip address
 328          */
 329         if (inc->inc_isipv6)
 330                 hash = HOSTCACHE_HASH6(&inc->inc6_faddr);
 331         else
 332                 hash = HOSTCACHE_HASH(&inc->inc_faddr);
 333
 334         hc_head = &tcp_hostcache.hashbase[hash];
 335
 336         /*
 337          * aquire lock for this bucket row
 338          * we release the lock if we don't find an entry,
 339          * otherwise the caller has to unlock after he is done
 340          */
 341         THC_LOCK(&hc_head->hch_mtx);
 342
 343         /*
 344          * If the bucket limit is reached reuse the least used element
 345          */
 346         if (hc_head->hch_length >= tcp_hostcache.bucket_limit ||
 347             tcp_hostcache.cache_count >= tcp_hostcache.cache_limit) {
 348                 hc_entry = TAILQ_LAST(&hc_head->hch_bucket, hc_qhead);
 349                 /*
 350                  * At first we were dropping the last element, just to
 351                  * reaquire it in the next two lines again which ain't
 352                  * very efficient. Instead just reuse the least used element.
 353                  * Maybe we drop something that is still "in-use" but we can
 354                  * be "lossy".
 355                  */
 356                 TAILQ_REMOVE(&hc_head->hch_bucket, hc_entry, rmx_q);
 357                 tcp_hostcache.hashbase[hash].hch_length--;
 358                 tcp_hostcache.cache_count--;
 359                 tcpstat.tcps_hc_bucketoverflow++;
 360 #if 0
 361                 uma_zfree(tcp_hostcache.zone, hc_entry);
 362 #endif
 363         } else {
 364                 /*
 365                  * Allocate a new entry, or balk if not possible
 366                  */
 367                 hc_entry = uma_zalloc(tcp_hostcache.zone, M_NOWAIT);
 368                 if (hc_entry == NULL) {
 369                         THC_UNLOCK(&hc_head->hch_mtx);
 370                         return NULL;
 371                 }
 372         }
 373
 374         /*
 375          * Initialize basic information of hostcache entry
 376          */
 377         bzero(hc_entry, sizeof(*hc_entry));
 378         if (inc->inc_isipv6)
 379                 bcopy(&inc->inc6_faddr, &hc_entry->ip6, sizeof(hc_entry->ip6));
 380         else
 381                 hc_entry->ip4 = inc->inc_faddr;
 382         hc_entry->rmx_head = hc_head;
 383         hc_entry->rmx_expire = tcp_hostcache.expire;
 384
 385         /*
 386          * Put it upfront
 387          */
 388         TAILQ_INSERT_HEAD(&hc_head->hch_bucket, hc_entry, rmx_q);
 389         tcp_hostcache.hashbase[hash].hch_length++;
 390         tcp_hostcache.cache_count++;
 391         tcpstat.tcps_hc_added++;
 392
 393         return hc_entry;
 394 }
 395
 396 /*
 397  * External function: lookup an entry in the hostcache and fill out the
 398  * supplied tcp metrics structure.  Fills in null when no entry was found
 399  * or a value is not set.
 400  */
 401 void
 402 tcp_hc_get(struct in_conninfo *inc, struct hc_metrics_lite *hc_metrics_lite)
 403 {
 404         struct hc_metrics *hc_entry;
 405
 406         /*
 407          * Find the right bucket
 408          */
 409         hc_entry = tcp_hc_lookup(inc);
 410
 411         /*
 412          * If we don't have an existing object
 413          */
 414         if (hc_entry == NULL) {
 415                 bzero(hc_metrics_lite, sizeof(*hc_metrics_lite));
 416                 return;
 417         }
 418         hc_entry->rmx_hits++;
 419         hc_entry->rmx_expire = tcp_hostcache.expire; /* start over again */
 420
 421         hc_metrics_lite->rmx_mtu = hc_entry->rmx_mtu;
 422         hc_metrics_lite->rmx_ssthresh = hc_entry->rmx_ssthresh;
 423         hc_metrics_lite->rmx_rtt = hc_entry->rmx_rtt;
 424         hc_metrics_lite->rmx_rttvar = hc_entry->rmx_rttvar;
 425         hc_metrics_lite->rmx_bandwidth = hc_entry->rmx_bandwidth;
 426         hc_metrics_lite->rmx_cwnd = hc_entry->rmx_cwnd;
 427         hc_metrics_lite->rmx_sendpipe = hc_entry->rmx_sendpipe;
 428         hc_metrics_lite->rmx_recvpipe = hc_entry->rmx_recvpipe;
 429
 430         /*
 431          * unlock bucket row
 432          */
 433         THC_UNLOCK(&hc_entry->rmx_head->hch_mtx);
 434 }
 435
 436 /*
 437  * External function: lookup an entry in the hostcache and return the
 438  * discovered path mtu.  Returns null if no entry is found or value is not
 439  * set.
 440  */
 441 u_long
 442 tcp_hc_getmtu(struct in_conninfo *inc)
 443 {
 444         struct hc_metrics *hc_entry;
 445         u_long mtu;
 446
 447         hc_entry = tcp_hc_lookup(inc);
 448         if (hc_entry == NULL) {
 449                 return 0;
 450         }
 451         hc_entry->rmx_hits++;
 452         hc_entry->rmx_expire = tcp_hostcache.expire; /* start over again */
 453
 454         mtu = hc_entry->rmx_mtu;
 455         THC_UNLOCK(&hc_entry->rmx_head->hch_mtx);
 456         return mtu;
 457 }
 458
 459 /*
 460  * External function: update the mtu value of an entry in the hostcache.
 461  * Creates a new entry if none was found.
 462  */
 463 void
 464 tcp_hc_updatemtu(struct in_conninfo *inc, u_long mtu)
 465 {
 466         struct hc_metrics *hc_entry;
 467
 468         /*
 469          * Find the right bucket
 470          */
 471         hc_entry = tcp_hc_lookup(inc);
 472
 473         /*
 474          * If we don't have an existing object try to insert a new one
 475          */
 476         if (hc_entry == NULL) {
 477                 hc_entry = tcp_hc_insert(inc);
 478                 if (hc_entry == NULL)
 479                         return;
 480         }
 481         hc_entry->rmx_updates++;
 482         hc_entry->rmx_expire = tcp_hostcache.expire; /* start over again */
 483
 484         hc_entry->rmx_mtu = mtu;
 485
 486         /*
 487          * put it upfront so we find it faster next time
 488          */
 489         TAILQ_REMOVE(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q);
 490         TAILQ_INSERT_HEAD(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q);
 491
 492         /*
 493          * unlock bucket row
 494          */
 495         THC_UNLOCK(&hc_entry->rmx_head->hch_mtx);
 496 }
 497
 498 /*
 499  * External function: update the tcp metrics of an entry in the hostcache.
 500  * Creates a new entry if none was found.
 501  */
 502 void
 503 tcp_hc_update(struct in_conninfo *inc, struct hc_metrics_lite *hcml)
 504 {
 505         struct hc_metrics *hc_entry;
 506
 507         hc_entry = tcp_hc_lookup(inc);
 508         if (hc_entry == NULL) {
 509                 hc_entry = tcp_hc_insert(inc);
 510                 if (hc_entry == NULL)
 511                         return;
 512         }
 513         hc_entry->rmx_updates++;
 514         hc_entry->rmx_expire = tcp_hostcache.expire; /* start over again */
 515
 516         if (hcml->rmx_rtt != 0) {
 517                 if (hc_entry->rmx_rtt == 0)
 518                         hc_entry->rmx_rtt = hcml->rmx_rtt;
 519                 else
 520                         hc_entry->rmx_rtt =
 521                             (hc_entry->rmx_rtt + hcml->rmx_rtt) / 2;
 522                 tcpstat.tcps_cachedrtt++;
 523         }
 524         if (hcml->rmx_rttvar != 0) {
 525                 if (hc_entry->rmx_rttvar == 0)
 526                         hc_entry->rmx_rttvar = hcml->rmx_rttvar;
 527                 else
 528                         hc_entry->rmx_rttvar =
 529                             (hc_entry->rmx_rttvar + hcml->rmx_rttvar) / 2;
 530                 tcpstat.tcps_cachedrttvar++;
 531         }
 532         if (hcml->rmx_ssthresh != 0) {
 533                 if (hc_entry->rmx_ssthresh == 0)
 534                         hc_entry->rmx_ssthresh = hcml->rmx_ssthresh;
 535                 else
 536                         hc_entry->rmx_ssthresh =
 537                             (hc_entry->rmx_ssthresh + hcml->rmx_ssthresh) / 2;
 538                 tcpstat.tcps_cachedssthresh++;
 539         }
 540         if (hcml->rmx_bandwidth != 0) {
 541                 if (hc_entry->rmx_bandwidth == 0)
 542                         hc_entry->rmx_bandwidth = hcml->rmx_bandwidth;
 543                 else
 544                         hc_entry->rmx_bandwidth =
 545                             (hc_entry->rmx_bandwidth + hcml->rmx_bandwidth) / 2;
 546                 /* tcpstat.tcps_cachedbandwidth++; */
 547         }
 548         if (hcml->rmx_cwnd != 0) {
 549                 if (hc_entry->rmx_cwnd == 0)
 550                         hc_entry->rmx_cwnd = hcml->rmx_cwnd;
 551                 else
 552                         hc_entry->rmx_cwnd =
 553                             (hc_entry->rmx_cwnd + hcml->rmx_cwnd) / 2;
 554                 /* tcpstat.tcps_cachedcwnd++; */
 555         }
 556         if (hcml->rmx_sendpipe != 0) {
 557                 if (hc_entry->rmx_sendpipe == 0)
 558                         hc_entry->rmx_sendpipe = hcml->rmx_sendpipe;
 559                 else
 560                         hc_entry->rmx_sendpipe =
 561                             (hc_entry->rmx_sendpipe + hcml->rmx_sendpipe) /2;
 562                 /* tcpstat.tcps_cachedsendpipe++; */
 563         }
 564         if (hcml->rmx_recvpipe != 0) {
 565                 if (hc_entry->rmx_recvpipe == 0)
 566                         hc_entry->rmx_recvpipe = hcml->rmx_recvpipe;
 567                 else
 568                         hc_entry->rmx_recvpipe =
 569                             (hc_entry->rmx_recvpipe + hcml->rmx_recvpipe) /2;
 570                 /* tcpstat.tcps_cachedrecvpipe++; */
 571         }
 572
 573         TAILQ_REMOVE(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q);
 574         TAILQ_INSERT_HEAD(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q);
 575         THC_UNLOCK(&hc_entry->rmx_head->hch_mtx);
 576 }
 577
 578 /*
 579  * Sysctl function: prints the list and values of all hostcache entries in
 580  * unsorted order.
 581  */
 582 static int
 583 sysctl_tcp_hc_list(SYSCTL_HANDLER_ARGS)
 584 {
 585         int bufsize;
 586         int linesize = 128;
 587         char *p, *buf;
 588         int len, i, error;
 589         struct hc_metrics *hc_entry;
 590 #ifdef INET6
 591         char ip6buf[INET6_ADDRSTRLEN];
 592 #endif
 593
 594         bufsize = linesize * (tcp_hostcache.cache_count + 1);
 595
 596         p = buf = (char *)malloc(bufsize, M_TEMP, M_WAITOK|M_ZERO);
 597
 598         len = snprintf(p, linesize,
 599                 "\nIP address        MTU  SSTRESH      RTT   RTTVAR BANDWIDTH "
 600                 "    CWND SENDPIPE RECVPIPE HITS  UPD  EXP\n");
 601         p += len;
 602
 603 #define msec(u) (((u) + 500) / 1000)
 604         for (i = 0; i < tcp_hostcache.hashsize; i++) {
 605                 THC_LOCK(&tcp_hostcache.hashbase[i].hch_mtx);
 606                 TAILQ_FOREACH(hc_entry, &tcp_hostcache.hashbase[i].hch_bucket,
 607                               rmx_q) {
 608                         len = snprintf(p, linesize,
 609                             "%-15s %5lu %8lu %6lums %6lums %9lu %8lu %8lu %8lu "
 610                             "%4lu %4lu %4i\n",
 611                             hc_entry->ip4.s_addr ? inet_ntoa(hc_entry->ip4) :
 612 #ifdef INET6
 613                                 ip6_sprintf(ip6buf, &hc_entry->ip6),
 614 #else
 615                                 "IPv6?",
 616 #endif
 617                             hc_entry->rmx_mtu,
 618                             hc_entry->rmx_ssthresh,
 619                             msec(hc_entry->rmx_rtt *
 620                                 (RTM_RTTUNIT / (hz * TCP_RTT_SCALE))),
 621                             msec(hc_entry->rmx_rttvar *
 622                                 (RTM_RTTUNIT / (hz * TCP_RTT_SCALE))),
 623                             hc_entry->rmx_bandwidth * 8,
 624                             hc_entry->rmx_cwnd,
 625                             hc_entry->rmx_sendpipe,
 626                             hc_entry->rmx_recvpipe,
 627                             hc_entry->rmx_hits,
 628                             hc_entry->rmx_updates,
 629                             hc_entry->rmx_expire);
 630                         p += len;
 631                 }
 632                 THC_UNLOCK(&tcp_hostcache.hashbase[i].hch_mtx);
 633         }
 634 #undef msec
 635         error = SYSCTL_OUT(req, buf, p - buf);
 636         free(buf, M_TEMP);
 637         return(error);
 638 }
 639
 640 /*
 641  * Expire and purge (old|all) entries in the tcp_hostcache.  Runs periodically
 642  * from the callout.
 643  */
 644 static void
 645 tcp_hc_purge(void *arg)
 646 {
 647         struct hc_metrics *hc_entry, *hc_next;
 648         int all = (intptr_t)arg;
 649         int i;
 650
 651         if (tcp_hostcache.purgeall) {
 652                 all = 1;
 653                 tcp_hostcache.purgeall = 0;
 654         }
 655
 656         for (i = 0; i < tcp_hostcache.hashsize; i++) {
 657                 THC_LOCK(&tcp_hostcache.hashbase[i].hch_mtx);
 658                 TAILQ_FOREACH_SAFE(hc_entry, &tcp_hostcache.hashbase[i].hch_bucket,
 659                               rmx_q, hc_next) {
 660                         if (all || hc_entry->rmx_expire <= 0) {
 661                                 TAILQ_REMOVE(&tcp_hostcache.hashbase[i].hch_bucket,
 662                                               hc_entry, rmx_q);
 663                                 uma_zfree(tcp_hostcache.zone, hc_entry);
 664                                 tcp_hostcache.hashbase[i].hch_length--;
 665                                 tcp_hostcache.cache_count--;
 666                         } else
 667                                 hc_entry->rmx_expire -= TCP_HOSTCACHE_PRUNE;
 668                 }
 669                 THC_UNLOCK(&tcp_hostcache.hashbase[i].hch_mtx);
 670         }
 671         callout_reset(&tcp_hc_callout, TCP_HOSTCACHE_PRUNE * hz, tcp_hc_purge, 0);
 672 }