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  * Copyright (c) 2021 Gleb Smirnoff <glebius@FreeBSD.org>
   6  * All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. The name of the author may not be used to endorse or promote
  17  *    products derived from this software without specific prior written
  18  *    permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  */
  32
  33 /*
  34  * The tcp_hostcache moves the tcp-specific cached metrics from the routing
  35  * table to a dedicated structure indexed by the remote IP address.  It keeps
  36  * information on the measured TCP parameters of past TCP sessions to allow
  37  * better initial start values to be used with later connections to/from the
  38  * same source.  Depending on the network parameters (delay, max MTU,
  39  * congestion window) between local and remote sites, this can lead to
  40  * significant speed-ups for new TCP connections after the first one.
  41  *
  42  * Due to the tcp_hostcache, all TCP-specific metrics information in the
  43  * routing table have been removed.  The inpcb no longer keeps a pointer to
  44  * the routing entry, and protocol-initiated route cloning has been removed
  45  * as well.  With these changes, the routing table has gone back to being
  46  * more lightwight and only carries information related to packet forwarding.
  47  *
  48  * tcp_hostcache is designed for multiple concurrent access in SMP
  49  * environments and high contention.  It is a straight hash.  Each bucket row
  50  * is protected by its own lock for modification.  Readers are protected by
  51  * SMR.  This puts certain restrictions on writers, e.g. a writer shall only
  52  * insert a fully populated entry into a row.  Writer can't reuse least used
  53  * entry if a hash is full.  Value updates for an entry shall be atomic.
  54  *
  55  * TCP stack(s) communication with tcp_hostcache() is done via KBI functions
  56  * tcp_hc_*() and the hc_metrics_lite structure.
  57  *
  58  * Since tcp_hostcache is only caching information, there are no fatal
  59  * consequences if we either can't allocate a new entry or have to drop
  60  * an existing entry, or return somewhat stale information.
  61  */
  62
  63 /*
  64  * Many thanks to jlemon for basic structure of tcp_syncache which is being
  65  * followed here.
  66  */
  67
  68 #include <sys/cdefs.h>
  69 __FBSDID("$FreeBSD$");
  70
  71 #include "opt_inet6.h"
  72
  73 #include <sys/param.h>
  74 #include <sys/systm.h>
  75 #include <sys/hash.h>
  76 #include <sys/jail.h>
  77 #include <sys/kernel.h>
  78 #include <sys/lock.h>
  79 #include <sys/mutex.h>
  80 #include <sys/malloc.h>
  81 #include <sys/proc.h>
  82 #include <sys/sbuf.h>
  83 #include <sys/smr.h>
  84 #include <sys/socket.h>
  85 #include <sys/socketvar.h>
  86 #include <sys/sysctl.h>
  87
  88 #include <net/vnet.h>
  89
  90 #include <netinet/in.h>
  91 #include <netinet/in_pcb.h>
  92 #include <netinet/tcp.h>
  93 #include <netinet/tcp_var.h>
  94
  95 #include <vm/uma.h>
  96
  97 struct hc_head {
  98         CK_SLIST_HEAD(hc_qhead, hc_metrics) hch_bucket;
  99         u_int           hch_length;
 100         struct mtx      hch_mtx;
 101 };
 102
 103 struct hc_metrics {
 104         /* housekeeping */
 105         CK_SLIST_ENTRY(hc_metrics) rmx_q;
 106         struct          in_addr ip4;    /* IP address */
 107         struct          in6_addr ip6;   /* IP6 address */
 108         uint32_t        ip6_zoneid;     /* IPv6 scope zone id */
 109         /* endpoint specific values for tcp */
 110         uint32_t        rmx_mtu;        /* MTU for this path */
 111         uint32_t        rmx_ssthresh;   /* outbound gateway buffer limit */
 112         uint32_t        rmx_rtt;        /* estimated round trip time */
 113         uint32_t        rmx_rttvar;     /* estimated rtt variance */
 114         uint32_t        rmx_cwnd;       /* congestion window */
 115         uint32_t        rmx_sendpipe;   /* outbound delay-bandwidth product */
 116         uint32_t        rmx_recvpipe;   /* inbound delay-bandwidth product */
 117         /* TCP hostcache internal data */
 118         int             rmx_expire;     /* lifetime for object */
 119 #ifdef  TCP_HC_COUNTERS
 120         u_long          rmx_hits;       /* number of hits */
 121         u_long          rmx_updates;    /* number of updates */
 122 #endif
 123 };
 124
 125 struct tcp_hostcache {
 126         struct hc_head  *hashbase;
 127         uma_zone_t      zone;
 128         smr_t           smr;
 129         u_int           hashsize;
 130         u_int           hashmask;
 131         u_int           hashsalt;
 132         u_int           bucket_limit;
 133         u_int           cache_count;
 134         u_int           cache_limit;
 135         int             expire;
 136         int             prune;
 137         int             purgeall;
 138 };
 139
 140 /* Arbitrary values */
 141 #define TCP_HOSTCACHE_HASHSIZE          512
 142 #define TCP_HOSTCACHE_BUCKETLIMIT       30
 143 #define TCP_HOSTCACHE_EXPIRE            60*60   /* one hour */
 144 #define TCP_HOSTCACHE_PRUNE             5*60    /* every 5 minutes */
 145
 146 VNET_DEFINE_STATIC(struct tcp_hostcache, tcp_hostcache);
 147 #define V_tcp_hostcache         VNET(tcp_hostcache)
 148
 149 VNET_DEFINE_STATIC(struct callout, tcp_hc_callout);
 150 #define V_tcp_hc_callout        VNET(tcp_hc_callout)
 151
 152 static struct hc_metrics *tcp_hc_lookup(struct in_conninfo *);
 153 static int sysctl_tcp_hc_list(SYSCTL_HANDLER_ARGS);
 154 static int sysctl_tcp_hc_histo(SYSCTL_HANDLER_ARGS);
 155 static int sysctl_tcp_hc_purgenow(SYSCTL_HANDLER_ARGS);
 156 static void tcp_hc_purge_internal(int);
 157 static void tcp_hc_purge(void *);
 158
 159 static SYSCTL_NODE(_net_inet_tcp, OID_AUTO, hostcache,
 160     CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
 161     "TCP Host cache");
 162
 163 VNET_DEFINE(int, tcp_use_hostcache) = 1;
 164 #define V_tcp_use_hostcache  VNET(tcp_use_hostcache)
 165 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, enable, CTLFLAG_VNET | CTLFLAG_RW,
 166     &VNET_NAME(tcp_use_hostcache), 0,
 167     "Enable the TCP hostcache");
 168
 169 SYSCTL_UINT(_net_inet_tcp_hostcache, OID_AUTO, cachelimit, CTLFLAG_VNET | CTLFLAG_RDTUN,
 170     &VNET_NAME(tcp_hostcache.cache_limit), 0,
 171     "Overall entry limit for hostcache");
 172
 173 SYSCTL_UINT(_net_inet_tcp_hostcache, OID_AUTO, hashsize, CTLFLAG_VNET | CTLFLAG_RDTUN,
 174     &VNET_NAME(tcp_hostcache.hashsize), 0,
 175     "Size of TCP hostcache hashtable");
 176
 177 SYSCTL_UINT(_net_inet_tcp_hostcache, OID_AUTO, bucketlimit,
 178     CTLFLAG_VNET | CTLFLAG_RDTUN, &VNET_NAME(tcp_hostcache.bucket_limit), 0,
 179     "Per-bucket hash limit for hostcache");
 180
 181 SYSCTL_UINT(_net_inet_tcp_hostcache, OID_AUTO, count, CTLFLAG_VNET | CTLFLAG_RD,
 182     &VNET_NAME(tcp_hostcache.cache_count), 0,
 183     "Current number of entries in hostcache");
 184
 185 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, expire, CTLFLAG_VNET | CTLFLAG_RW,
 186     &VNET_NAME(tcp_hostcache.expire), 0,
 187     "Expire time of TCP hostcache entries");
 188
 189 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, prune, CTLFLAG_VNET | CTLFLAG_RW,
 190     &VNET_NAME(tcp_hostcache.prune), 0,
 191     "Time between purge runs");
 192
 193 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, purge, CTLFLAG_VNET | CTLFLAG_RW,
 194     &VNET_NAME(tcp_hostcache.purgeall), 0,
 195     "Expire all entries on next purge run");
 196
 197 SYSCTL_PROC(_net_inet_tcp_hostcache, OID_AUTO, list,
 198     CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_SKIP | CTLFLAG_MPSAFE,
 199     0, 0, sysctl_tcp_hc_list, "A",
 200     "List of all hostcache entries");
 201
 202 SYSCTL_PROC(_net_inet_tcp_hostcache, OID_AUTO, histo,
 203     CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_SKIP | CTLFLAG_MPSAFE,
 204     0, 0, sysctl_tcp_hc_histo, "A",
 205     "Print a histogram of hostcache hashbucket utilization");
 206
 207 SYSCTL_PROC(_net_inet_tcp_hostcache, OID_AUTO, purgenow,
 208     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE,
 209     NULL, 0, sysctl_tcp_hc_purgenow, "I",
 210     "Immediately purge all entries");
 211
 212 static MALLOC_DEFINE(M_HOSTCACHE, "hostcache", "TCP hostcache");
 213
 214 /* Use jenkins_hash32(), as in other parts of the tcp stack */
 215 #define HOSTCACHE_HASH(inc)                                             \
 216         ((inc)->inc_flags & INC_ISIPV6) ?                               \
 217                 (jenkins_hash32((inc)->inc6_faddr.s6_addr32, 4,         \
 218                 V_tcp_hostcache.hashsalt) & V_tcp_hostcache.hashmask)   \
 219         :                                                               \
 220                 (jenkins_hash32(&(inc)->inc_faddr.s_addr, 1,            \
 221                 V_tcp_hostcache.hashsalt) & V_tcp_hostcache.hashmask)
 222
 223 #define THC_LOCK(h)             mtx_lock(&(h)->hch_mtx)
 224 #define THC_UNLOCK(h)           mtx_unlock(&(h)->hch_mtx)
 225
 226 void
 227 tcp_hc_init(void)
 228 {
 229         u_int cache_limit;
 230         int i;
 231
 232         /*
 233          * Initialize hostcache structures.
 234          */
 235         atomic_store_int(&V_tcp_hostcache.cache_count, 0);
 236         V_tcp_hostcache.hashsize = TCP_HOSTCACHE_HASHSIZE;
 237         V_tcp_hostcache.bucket_limit = TCP_HOSTCACHE_BUCKETLIMIT;
 238         V_tcp_hostcache.expire = TCP_HOSTCACHE_EXPIRE;
 239         V_tcp_hostcache.prune = TCP_HOSTCACHE_PRUNE;
 240         V_tcp_hostcache.hashsalt = arc4random();
 241
 242         TUNABLE_INT_FETCH("net.inet.tcp.hostcache.hashsize",
 243             &V_tcp_hostcache.hashsize);
 244         if (!powerof2(V_tcp_hostcache.hashsize)) {
 245                 printf("WARNING: hostcache hash size is not a power of 2.\n");
 246                 V_tcp_hostcache.hashsize = TCP_HOSTCACHE_HASHSIZE; /* default */
 247         }
 248         V_tcp_hostcache.hashmask = V_tcp_hostcache.hashsize - 1;
 249
 250         TUNABLE_INT_FETCH("net.inet.tcp.hostcache.bucketlimit",
 251             &V_tcp_hostcache.bucket_limit);
 252
 253         cache_limit = V_tcp_hostcache.hashsize * V_tcp_hostcache.bucket_limit;
 254         V_tcp_hostcache.cache_limit = cache_limit;
 255         TUNABLE_INT_FETCH("net.inet.tcp.hostcache.cachelimit",
 256             &V_tcp_hostcache.cache_limit);
 257         if (V_tcp_hostcache.cache_limit > cache_limit)
 258                 V_tcp_hostcache.cache_limit = cache_limit;
 259
 260         /*
 261          * Allocate the hash table.
 262          */
 263         V_tcp_hostcache.hashbase = (struct hc_head *)
 264             malloc(V_tcp_hostcache.hashsize * sizeof(struct hc_head),
 265                    M_HOSTCACHE, M_WAITOK | M_ZERO);
 266
 267         /*
 268          * Initialize the hash buckets.
 269          */
 270         for (i = 0; i < V_tcp_hostcache.hashsize; i++) {
 271                 CK_SLIST_INIT(&V_tcp_hostcache.hashbase[i].hch_bucket);
 272                 V_tcp_hostcache.hashbase[i].hch_length = 0;
 273                 mtx_init(&V_tcp_hostcache.hashbase[i].hch_mtx, "tcp_hc_entry",
 274                           NULL, MTX_DEF);
 275         }
 276
 277         /*
 278          * Allocate the hostcache entries.
 279          */
 280         V_tcp_hostcache.zone =
 281             uma_zcreate("hostcache", sizeof(struct hc_metrics),
 282             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_SMR);
 283         uma_zone_set_max(V_tcp_hostcache.zone, V_tcp_hostcache.cache_limit);
 284         V_tcp_hostcache.smr = uma_zone_get_smr(V_tcp_hostcache.zone);
 285
 286         /*
 287          * Set up periodic cache cleanup.
 288          */
 289         callout_init(&V_tcp_hc_callout, 1);
 290         callout_reset(&V_tcp_hc_callout, V_tcp_hostcache.prune * hz,
 291             tcp_hc_purge, curvnet);
 292 }
 293
 294 #ifdef VIMAGE
 295 void
 296 tcp_hc_destroy(void)
 297 {
 298         int i;
 299
 300         callout_drain(&V_tcp_hc_callout);
 301
 302         /* Purge all hc entries. */
 303         tcp_hc_purge_internal(1);
 304
 305         /* Free the uma zone and the allocated hash table. */
 306         uma_zdestroy(V_tcp_hostcache.zone);
 307
 308         for (i = 0; i < V_tcp_hostcache.hashsize; i++)
 309                 mtx_destroy(&V_tcp_hostcache.hashbase[i].hch_mtx);
 310         free(V_tcp_hostcache.hashbase, M_HOSTCACHE);
 311 }
 312 #endif
 313
 314 /*
 315  * Internal function: compare cache entry to a connection.
 316  */
 317 static bool
 318 tcp_hc_cmp(struct hc_metrics *hc_entry, struct in_conninfo *inc)
 319 {
 320
 321         if (inc->inc_flags & INC_ISIPV6) {
 322                 /* XXX: check ip6_zoneid */
 323                 if (memcmp(&inc->inc6_faddr, &hc_entry->ip6,
 324                     sizeof(inc->inc6_faddr)) == 0)
 325                         return (true);
 326         } else {
 327                 if (memcmp(&inc->inc_faddr, &hc_entry->ip4,
 328                     sizeof(inc->inc_faddr)) == 0)
 329                         return (true);
 330         }
 331
 332         return (false);
 333 }
 334
 335 /*
 336  * Internal function: look up an entry in the hostcache for read.
 337  * On success returns in SMR section.
 338  */
 339 static struct hc_metrics *
 340 tcp_hc_lookup(struct in_conninfo *inc)
 341 {
 342         struct hc_head *hc_head;
 343         struct hc_metrics *hc_entry;
 344
 345         KASSERT(inc != NULL, ("%s: NULL in_conninfo", __func__));
 346
 347         hc_head = &V_tcp_hostcache.hashbase[HOSTCACHE_HASH(inc)];
 348
 349         /*
 350          * Iterate through entries in bucket row looking for a match.
 351          */
 352         smr_enter(V_tcp_hostcache.smr);
 353         CK_SLIST_FOREACH(hc_entry, &hc_head->hch_bucket, rmx_q)
 354                 if (tcp_hc_cmp(hc_entry, inc))
 355                         break;
 356
 357         if (hc_entry != NULL) {
 358                 if (atomic_load_int(&hc_entry->rmx_expire) !=
 359                     V_tcp_hostcache.expire)
 360                         atomic_store_int(&hc_entry->rmx_expire,
 361                             V_tcp_hostcache.expire);
 362 #ifdef  TCP_HC_COUNTERS
 363                 hc_entry->rmx_hits++;
 364 #endif
 365         } else
 366                 smr_exit(V_tcp_hostcache.smr);
 367
 368         return (hc_entry);
 369 }
 370
 371 /*
 372  * External function: look up an entry in the hostcache and fill out the
 373  * supplied TCP metrics structure.  Fills in NULL when no entry was found or
 374  * a value is not set.
 375  */
 376 void
 377 tcp_hc_get(struct in_conninfo *inc, struct hc_metrics_lite *hc_metrics_lite)
 378 {
 379         struct hc_metrics *hc_entry;
 380
 381         if (!V_tcp_use_hostcache) {
 382                 bzero(hc_metrics_lite, sizeof(*hc_metrics_lite));
 383                 return;
 384         }
 385
 386         /*
 387          * Find the right bucket.
 388          */
 389         hc_entry = tcp_hc_lookup(inc);
 390
 391         /*
 392          * If we don't have an existing object.
 393          */
 394         if (hc_entry == NULL) {
 395                 bzero(hc_metrics_lite, sizeof(*hc_metrics_lite));
 396                 return;
 397         }
 398
 399         hc_metrics_lite->rmx_mtu = atomic_load_32(&hc_entry->rmx_mtu);
 400         hc_metrics_lite->rmx_ssthresh = atomic_load_32(&hc_entry->rmx_ssthresh);
 401         hc_metrics_lite->rmx_rtt = atomic_load_32(&hc_entry->rmx_rtt);
 402         hc_metrics_lite->rmx_rttvar = atomic_load_32(&hc_entry->rmx_rttvar);
 403         hc_metrics_lite->rmx_cwnd = atomic_load_32(&hc_entry->rmx_cwnd);
 404         hc_metrics_lite->rmx_sendpipe = atomic_load_32(&hc_entry->rmx_sendpipe);
 405         hc_metrics_lite->rmx_recvpipe = atomic_load_32(&hc_entry->rmx_recvpipe);
 406
 407         smr_exit(V_tcp_hostcache.smr);
 408 }
 409
 410 /*
 411  * External function: look up an entry in the hostcache and return the
 412  * discovered path MTU.  Returns 0 if no entry is found or value is not
 413  * set.
 414  */
 415 uint32_t
 416 tcp_hc_getmtu(struct in_conninfo *inc)
 417 {
 418         struct hc_metrics *hc_entry;
 419         uint32_t mtu;
 420
 421         if (!V_tcp_use_hostcache)
 422                 return (0);
 423
 424         hc_entry = tcp_hc_lookup(inc);
 425         if (hc_entry == NULL) {
 426                 return (0);
 427         }
 428
 429         mtu = atomic_load_32(&hc_entry->rmx_mtu);
 430         smr_exit(V_tcp_hostcache.smr);
 431
 432         return (mtu);
 433 }
 434
 435 /*
 436  * External function: update the MTU value of an entry in the hostcache.
 437  * Creates a new entry if none was found.
 438  */
 439 void
 440 tcp_hc_updatemtu(struct in_conninfo *inc, uint32_t mtu)
 441 {
 442         struct hc_metrics_lite hcml = { .rmx_mtu = mtu };
 443
 444         return (tcp_hc_update(inc, &hcml));
 445 }
 446
 447 /*
 448  * External function: update the TCP metrics of an entry in the hostcache.
 449  * Creates a new entry if none was found.
 450  */
 451 void
 452 tcp_hc_update(struct in_conninfo *inc, struct hc_metrics_lite *hcml)
 453 {
 454         struct hc_head *hc_head;
 455         struct hc_metrics *hc_entry, *hc_prev;
 456         uint32_t v;
 457         bool new;
 458
 459         if (!V_tcp_use_hostcache)
 460                 return;
 461
 462         hc_head = &V_tcp_hostcache.hashbase[HOSTCACHE_HASH(inc)];
 463         hc_prev = NULL;
 464
 465         THC_LOCK(hc_head);
 466         CK_SLIST_FOREACH(hc_entry, &hc_head->hch_bucket, rmx_q) {
 467                 if (tcp_hc_cmp(hc_entry, inc))
 468                         break;
 469                 if (CK_SLIST_NEXT(hc_entry, rmx_q) != NULL)
 470                         hc_prev = hc_entry;
 471         }
 472
 473         if (hc_entry != NULL) {
 474                 if (atomic_load_int(&hc_entry->rmx_expire) !=
 475                     V_tcp_hostcache.expire)
 476                         atomic_store_int(&hc_entry->rmx_expire,
 477                             V_tcp_hostcache.expire);
 478 #ifdef  TCP_HC_COUNTERS
 479                 hc_entry->rmx_updates++;
 480 #endif
 481                 new = false;
 482         } else {
 483                 /*
 484                  * Try to allocate a new entry.  If the bucket limit is
 485                  * reached, delete the least-used element, located at the end
 486                  * of the CK_SLIST.  During lookup we saved the pointer to
 487                  * the second to last element, in case if list has at least 2
 488                  * elements.  This will allow to delete last element without
 489                  * extra traversal.
 490                  *
 491                  * Give up if the row is empty.
 492                  */
 493                 if (hc_head->hch_length >= V_tcp_hostcache.bucket_limit ||
 494                     atomic_load_int(&V_tcp_hostcache.cache_count) >=
 495                     V_tcp_hostcache.cache_limit) {
 496                         if (hc_prev != NULL) {
 497                                 hc_entry = CK_SLIST_NEXT(hc_prev, rmx_q);
 498                                 KASSERT(CK_SLIST_NEXT(hc_entry, rmx_q) == NULL,
 499                                     ("%s: %p is not one to last",
 500                                     __func__, hc_prev));
 501                                 CK_SLIST_REMOVE_AFTER(hc_prev, rmx_q);
 502                         } else if ((hc_entry =
 503                             CK_SLIST_FIRST(&hc_head->hch_bucket)) != NULL) {
 504                                 KASSERT(CK_SLIST_NEXT(hc_entry, rmx_q) == NULL,
 505                                     ("%s: %p is not the only element",
 506                                     __func__, hc_entry));
 507                                 CK_SLIST_REMOVE_HEAD(&hc_head->hch_bucket,
 508                                     rmx_q);
 509                         } else {
 510                                 THC_UNLOCK(hc_head);
 511                                 return;
 512                         }
 513                         KASSERT(hc_head->hch_length > 0 &&
 514                             hc_head->hch_length <= V_tcp_hostcache.bucket_limit,
 515                             ("tcp_hostcache: bucket length violated at %p",
 516                             hc_head));
 517                         hc_head->hch_length--;
 518                         atomic_subtract_int(&V_tcp_hostcache.cache_count, 1);
 519                         TCPSTAT_INC(tcps_hc_bucketoverflow);
 520                         uma_zfree_smr(V_tcp_hostcache.zone, hc_entry);
 521                 }
 522
 523                 /*
 524                  * Allocate a new entry, or balk if not possible.
 525                  */
 526                 hc_entry = uma_zalloc_smr(V_tcp_hostcache.zone, M_NOWAIT);
 527                 if (hc_entry == NULL) {
 528                         THC_UNLOCK(hc_head);
 529                         return;
 530                 }
 531
 532                 /*
 533                  * Initialize basic information of hostcache entry.
 534                  */
 535                 bzero(hc_entry, sizeof(*hc_entry));
 536                 if (inc->inc_flags & INC_ISIPV6) {
 537                         hc_entry->ip6 = inc->inc6_faddr;
 538                         hc_entry->ip6_zoneid = inc->inc6_zoneid;
 539                 } else
 540                         hc_entry->ip4 = inc->inc_faddr;
 541                 hc_entry->rmx_expire = V_tcp_hostcache.expire;
 542                 new = true;
 543         }
 544
 545         /*
 546          * Fill in data.  Use atomics, since an existing entry is
 547          * accessible by readers in SMR section.
 548          */
 549         if (hcml->rmx_mtu != 0) {
 550                 atomic_store_32(&hc_entry->rmx_mtu, hcml->rmx_mtu);
 551         }
 552         if (hcml->rmx_rtt != 0) {
 553                 if (hc_entry->rmx_rtt == 0)
 554                         v = hcml->rmx_rtt;
 555                 else
 556                         v = ((uint64_t)hc_entry->rmx_rtt +
 557                             (uint64_t)hcml->rmx_rtt) / 2;
 558                 atomic_store_32(&hc_entry->rmx_rtt, v);
 559                 TCPSTAT_INC(tcps_cachedrtt);
 560         }
 561         if (hcml->rmx_rttvar != 0) {
 562                 if (hc_entry->rmx_rttvar == 0)
 563                         v = hcml->rmx_rttvar;
 564                 else
 565                         v = ((uint64_t)hc_entry->rmx_rttvar +
 566                             (uint64_t)hcml->rmx_rttvar) / 2;
 567                 atomic_store_32(&hc_entry->rmx_rttvar, v);
 568                 TCPSTAT_INC(tcps_cachedrttvar);
 569         }
 570         if (hcml->rmx_ssthresh != 0) {
 571                 if (hc_entry->rmx_ssthresh == 0)
 572                         v = hcml->rmx_ssthresh;
 573                 else
 574                         v = (hc_entry->rmx_ssthresh + hcml->rmx_ssthresh) / 2;
 575                 atomic_store_32(&hc_entry->rmx_ssthresh, v);
 576                 TCPSTAT_INC(tcps_cachedssthresh);
 577         }
 578         if (hcml->rmx_cwnd != 0) {
 579                 if (hc_entry->rmx_cwnd == 0)
 580                         v = hcml->rmx_cwnd;
 581                 else
 582                         v = ((uint64_t)hc_entry->rmx_cwnd +
 583                             (uint64_t)hcml->rmx_cwnd) / 2;
 584                 atomic_store_32(&hc_entry->rmx_cwnd, v);
 585                 /* TCPSTAT_INC(tcps_cachedcwnd); */
 586         }
 587         if (hcml->rmx_sendpipe != 0) {
 588                 if (hc_entry->rmx_sendpipe == 0)
 589                         v = hcml->rmx_sendpipe;
 590                 else
 591                         v = ((uint64_t)hc_entry->rmx_sendpipe +
 592                             (uint64_t)hcml->rmx_sendpipe) /2;
 593                 atomic_store_32(&hc_entry->rmx_sendpipe, v);
 594                 /* TCPSTAT_INC(tcps_cachedsendpipe); */
 595         }
 596         if (hcml->rmx_recvpipe != 0) {
 597                 if (hc_entry->rmx_recvpipe == 0)
 598                         v = hcml->rmx_recvpipe;
 599                 else
 600                         v = ((uint64_t)hc_entry->rmx_recvpipe +
 601                             (uint64_t)hcml->rmx_recvpipe) /2;
 602                 atomic_store_32(&hc_entry->rmx_recvpipe, v);
 603                 /* TCPSTAT_INC(tcps_cachedrecvpipe); */
 604         }
 605
 606         /*
 607          * Put it upfront.
 608          */
 609         if (new) {
 610                 CK_SLIST_INSERT_HEAD(&hc_head->hch_bucket, hc_entry, rmx_q);
 611                 hc_head->hch_length++;
 612                 KASSERT(hc_head->hch_length <= V_tcp_hostcache.bucket_limit,
 613                     ("tcp_hostcache: bucket length too high at %p", hc_head));
 614                 atomic_add_int(&V_tcp_hostcache.cache_count, 1);
 615                 TCPSTAT_INC(tcps_hc_added);
 616         } else if (hc_entry != CK_SLIST_FIRST(&hc_head->hch_bucket)) {
 617                 KASSERT(CK_SLIST_NEXT(hc_prev, rmx_q) == hc_entry,
 618                     ("%s: %p next is not %p", __func__, hc_prev, hc_entry));
 619                 CK_SLIST_REMOVE_AFTER(hc_prev, rmx_q);
 620                 CK_SLIST_INSERT_HEAD(&hc_head->hch_bucket, hc_entry, rmx_q);
 621         }
 622         THC_UNLOCK(hc_head);
 623 }
 624
 625 /*
 626  * Sysctl function: prints the list and values of all hostcache entries in
 627  * unsorted order.
 628  */
 629 static int
 630 sysctl_tcp_hc_list(SYSCTL_HANDLER_ARGS)
 631 {
 632         const int linesize = 128;
 633         struct sbuf sb;
 634         int i, error, len;
 635         struct hc_metrics *hc_entry;
 636         char ip4buf[INET_ADDRSTRLEN];
 637 #ifdef INET6
 638         char ip6buf[INET6_ADDRSTRLEN];
 639 #endif
 640
 641         if (jailed_without_vnet(curthread->td_ucred) != 0)
 642                 return (EPERM);
 643
 644         /* Optimize Buffer length query by sbin/sysctl */
 645         if (req->oldptr == NULL) {
 646                 len = (atomic_load_int(&V_tcp_hostcache.cache_count) + 1) *
 647                         linesize;
 648                 return (SYSCTL_OUT(req, NULL, len));
 649         }
 650
 651         error = sysctl_wire_old_buffer(req, 0);
 652         if (error != 0) {
 653                 return(error);
 654         }
 655
 656         /* Use a buffer sized for one full bucket */
 657         sbuf_new_for_sysctl(&sb, NULL, V_tcp_hostcache.bucket_limit *
 658                 linesize, req);
 659
 660         sbuf_printf(&sb,
 661                 "\nIP address        MTU  SSTRESH      RTT   RTTVAR "
 662                 "    CWND SENDPIPE RECVPIPE "
 663 #ifdef  TCP_HC_COUNTERS
 664                 "HITS  UPD  "
 665 #endif
 666                 "EXP\n");
 667         sbuf_drain(&sb);
 668
 669 #define msec(u) (((u) + 500) / 1000)
 670         for (i = 0; i < V_tcp_hostcache.hashsize; i++) {
 671                 THC_LOCK(&V_tcp_hostcache.hashbase[i]);
 672                 CK_SLIST_FOREACH(hc_entry,
 673                     &V_tcp_hostcache.hashbase[i].hch_bucket, rmx_q) {
 674                         sbuf_printf(&sb,
 675                             "%-15s %5u %8u %6lums %6lums %8u %8u %8u "
 676 #ifdef  TCP_HC_COUNTERS
 677                             "%4lu %4lu "
 678 #endif
 679                             "%4i\n",
 680                             hc_entry->ip4.s_addr ?
 681                                 inet_ntoa_r(hc_entry->ip4, ip4buf) :
 682 #ifdef INET6
 683                                 ip6_sprintf(ip6buf, &hc_entry->ip6),
 684 #else
 685                                 "IPv6?",
 686 #endif
 687                             hc_entry->rmx_mtu,
 688                             hc_entry->rmx_ssthresh,
 689                             msec((u_long)hc_entry->rmx_rtt *
 690                                 (RTM_RTTUNIT / (hz * TCP_RTT_SCALE))),
 691                             msec((u_long)hc_entry->rmx_rttvar *
 692                                 (RTM_RTTUNIT / (hz * TCP_RTTVAR_SCALE))),
 693                             hc_entry->rmx_cwnd,
 694                             hc_entry->rmx_sendpipe,
 695                             hc_entry->rmx_recvpipe,
 696 #ifdef  TCP_HC_COUNTERS
 697                             hc_entry->rmx_hits,
 698                             hc_entry->rmx_updates,
 699 #endif
 700                             hc_entry->rmx_expire);
 701                 }
 702                 THC_UNLOCK(&V_tcp_hostcache.hashbase[i]);
 703                 sbuf_drain(&sb);
 704         }
 705 #undef msec
 706         error = sbuf_finish(&sb);
 707         sbuf_delete(&sb);
 708         return(error);
 709 }
 710
 711 /*
 712  * Sysctl function: prints a histogram of the hostcache hashbucket
 713  * utilization.
 714  */
 715 static int
 716 sysctl_tcp_hc_histo(SYSCTL_HANDLER_ARGS)
 717 {
 718         const int linesize = 50;
 719         struct sbuf sb;
 720         int i, error;
 721         int *histo;
 722         u_int hch_length;
 723
 724         if (jailed_without_vnet(curthread->td_ucred) != 0)
 725                 return (EPERM);
 726
 727         histo = (int *)malloc(sizeof(int) * (V_tcp_hostcache.bucket_limit + 1),
 728                         M_TEMP, M_NOWAIT|M_ZERO);
 729         if (histo == NULL)
 730                 return(ENOMEM);
 731
 732         for (i = 0; i < V_tcp_hostcache.hashsize; i++) {
 733                 hch_length = V_tcp_hostcache.hashbase[i].hch_length;
 734                 KASSERT(hch_length <= V_tcp_hostcache.bucket_limit,
 735                     ("tcp_hostcache: bucket limit exceeded at %u: %u",
 736                     i, hch_length));
 737                 histo[hch_length]++;
 738         }
 739
 740         /* Use a buffer for 16 lines */
 741         sbuf_new_for_sysctl(&sb, NULL, 16 * linesize, req);
 742
 743         sbuf_printf(&sb, "\nLength\tCount\n");
 744         for (i = 0; i <= V_tcp_hostcache.bucket_limit; i++) {
 745                 sbuf_printf(&sb, "%u\t%u\n", i, histo[i]);
 746         }
 747         error = sbuf_finish(&sb);
 748         sbuf_delete(&sb);
 749         free(histo, M_TEMP);
 750         return(error);
 751 }
 752
 753 /*
 754  * Caller has to make sure the curvnet is set properly.
 755  */
 756 static void
 757 tcp_hc_purge_internal(int all)
 758 {
 759         struct hc_head *head;
 760         struct hc_metrics *hc_entry, *hc_next, *hc_prev;
 761         int i;
 762
 763         for (i = 0; i < V_tcp_hostcache.hashsize; i++) {
 764                 head = &V_tcp_hostcache.hashbase[i];
 765                 hc_prev = NULL;
 766                 THC_LOCK(head);
 767                 CK_SLIST_FOREACH_SAFE(hc_entry, &head->hch_bucket, rmx_q,
 768                     hc_next) {
 769                         KASSERT(head->hch_length > 0 && head->hch_length <=
 770                             V_tcp_hostcache.bucket_limit, ("tcp_hostcache: "
 771                             "bucket length out of range at %u: %u", i,
 772                             head->hch_length));
 773                         if (all ||
 774                             atomic_load_int(&hc_entry->rmx_expire) <= 0) {
 775                                 if (hc_prev != NULL) {
 776                                         KASSERT(hc_entry ==
 777                                             CK_SLIST_NEXT(hc_prev, rmx_q),
 778                                             ("%s: %p is not next to %p",
 779                                             __func__, hc_entry, hc_prev));
 780                                         CK_SLIST_REMOVE_AFTER(hc_prev, rmx_q);
 781                                 } else {
 782                                         KASSERT(hc_entry ==
 783                                             CK_SLIST_FIRST(&head->hch_bucket),
 784                                             ("%s: %p is not first",
 785                                             __func__, hc_entry));
 786                                         CK_SLIST_REMOVE_HEAD(&head->hch_bucket,
 787                                             rmx_q);
 788                                 }
 789                                 uma_zfree_smr(V_tcp_hostcache.zone, hc_entry);
 790                                 head->hch_length--;
 791                                 atomic_subtract_int(&V_tcp_hostcache.cache_count, 1);
 792                         } else {
 793                                 atomic_subtract_int(&hc_entry->rmx_expire,
 794                                     V_tcp_hostcache.prune);
 795                                 hc_prev = hc_entry;
 796                         }
 797                 }
 798                 THC_UNLOCK(head);
 799         }
 800 }
 801
 802 /*
 803  * Expire and purge (old|all) entries in the tcp_hostcache.  Runs
 804  * periodically from the callout.
 805  */
 806 static void
 807 tcp_hc_purge(void *arg)
 808 {
 809         CURVNET_SET((struct vnet *) arg);
 810         int all = 0;
 811
 812         if (V_tcp_hostcache.purgeall) {
 813                 if (V_tcp_hostcache.purgeall == 2)
 814                         V_tcp_hostcache.hashsalt = arc4random();
 815                 all = 1;
 816                 V_tcp_hostcache.purgeall = 0;
 817         }
 818
 819         tcp_hc_purge_internal(all);
 820
 821         callout_reset(&V_tcp_hc_callout, V_tcp_hostcache.prune * hz,
 822             tcp_hc_purge, arg);
 823         CURVNET_RESTORE();
 824 }
 825
 826 /*
 827  * Expire and purge all entries in hostcache immediately.
 828  */
 829 static int
 830 sysctl_tcp_hc_purgenow(SYSCTL_HANDLER_ARGS)
 831 {
 832         int error, val;
 833
 834         val = 0;
 835         error = sysctl_handle_int(oidp, &val, 0, req);
 836         if (error || !req->newptr)
 837                 return (error);
 838
 839         if (val == 2)
 840                 V_tcp_hostcache.hashsalt = arc4random();
 841         tcp_hc_purge_internal(1);
 842
 843         callout_reset(&V_tcp_hc_callout, V_tcp_hostcache.prune * hz,
 844             tcp_hc_purge, curvnet);
 845
 846         return (0);
 847 }