tcp_hostcache.c

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    1 /*-
    2  * Copyright (c) 2002 Andre Oppermann, Internet Business Solutions AG
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  * 3. The name of the author may not be used to endorse or promote
   14  *    products derived from this software without specific prior written
   15  *    permission.
   16  *
   17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   27  * SUCH DAMAGE.
   28  */
   29 
   30 /*
   31  * The tcp_hostcache moves the tcp-specific cached metrics from the routing
   32  * table to a dedicated structure indexed by the remote IP address.  It keeps
   33  * information on the measured TCP parameters of past TCP sessions to allow
   34  * better initial start values to be used with later connections to/from the
   35  * same source.  Depending on the network parameters (delay, max MTU,
   36  * congestion window) between local and remote sites, this can lead to
   37  * significant speed-ups for new TCP connections after the first one.
   38  *
   39  * Due to the tcp_hostcache, all TCP-specific metrics information in the
   40  * routing table have been removed.  The inpcb no longer keeps a pointer to
   41  * the routing entry, and protocol-initiated route cloning has been removed
   42  * as well.  With these changes, the routing table has gone back to being
   43  * more lightwight and only carries information related to packet forwarding.
   44  *
   45  * tcp_hostcache is designed for multiple concurrent access in SMP
   46  * environments and high contention.  All bucket rows have their own lock and
   47  * thus multiple lookups and modifies can be done at the same time as long as
   48  * they are in different bucket rows.  If a request for insertion of a new
   49  * record can't be satisfied, it simply returns an empty structure.  Nobody
   50  * and nothing outside of tcp_hostcache.c will ever point directly to any
   51  * entry in the tcp_hostcache.  All communication is done in an
   52  * object-oriented way and only functions of tcp_hostcache will manipulate
   53  * hostcache entries.  Otherwise, we are unable to achieve good behaviour in
   54  * concurrent access situations.  Since tcp_hostcache is only caching
   55  * information, there are no fatal consequences if we either can't satisfy
   56  * any particular request or have to drop/overwrite an existing entry because
   57  * of bucket limit memory constrains.
   58  */
   59 
   60 /*
   61  * Many thanks to jlemon for basic structure of tcp_syncache which is being
   62  * followed here.
   63  */
   64 
   65 #include <sys/cdefs.h>
   66 __FBSDID("$FreeBSD: releng/11.2/sys/netinet/tcp_hostcache.c 315456 2017-03-17 14:54:10Z vangyzen $");
   67 
   68 #include "opt_inet6.h"
   69 
   70 #include <sys/param.h>
   71 #include <sys/systm.h>
   72 #include <sys/jail.h>
   73 #include <sys/kernel.h>
   74 #include <sys/lock.h>
   75 #include <sys/mutex.h>
   76 #include <sys/malloc.h>
   77 #include <sys/proc.h>
   78 #include <sys/sbuf.h>
   79 #include <sys/socket.h>
   80 #include <sys/socketvar.h>
   81 #include <sys/sysctl.h>
   82 
   83 #include <net/if.h>
   84 #include <net/if_var.h>
   85 #include <net/route.h>
   86 #include <net/vnet.h>
   87 
   88 #include <netinet/in.h>
   89 #include <netinet/in_systm.h>
   90 #include <netinet/ip.h>
   91 #include <netinet/in_var.h>
   92 #include <netinet/in_pcb.h>
   93 #include <netinet/ip_var.h>
   94 #ifdef INET6
   95 #include <netinet/ip6.h>
   96 #include <netinet6/ip6_var.h>
   97 #endif
   98 #include <netinet/tcp.h>
   99 #include <netinet/tcp_var.h>
  100 #include <netinet/tcp_hostcache.h>
  101 #ifdef INET6
  102 #include <netinet6/tcp6_var.h>
  103 #endif
  104 
  105 #include <vm/uma.h>
  106 
  107 /* Arbitrary values */
  108 #define TCP_HOSTCACHE_HASHSIZE          512
  109 #define TCP_HOSTCACHE_BUCKETLIMIT       30
  110 #define TCP_HOSTCACHE_EXPIRE            60*60   /* one hour */
  111 #define TCP_HOSTCACHE_PRUNE             5*60    /* every 5 minutes */
  112 
  113 static VNET_DEFINE(struct tcp_hostcache, tcp_hostcache);
  114 #define V_tcp_hostcache         VNET(tcp_hostcache)
  115 
  116 static VNET_DEFINE(struct callout, tcp_hc_callout);
  117 #define V_tcp_hc_callout        VNET(tcp_hc_callout)
  118 
  119 static struct hc_metrics *tcp_hc_lookup(struct in_conninfo *);
  120 static struct hc_metrics *tcp_hc_insert(struct in_conninfo *);
  121 static int sysctl_tcp_hc_list(SYSCTL_HANDLER_ARGS);
  122 static int sysctl_tcp_hc_purgenow(SYSCTL_HANDLER_ARGS);
  123 static void tcp_hc_purge_internal(int);
  124 static void tcp_hc_purge(void *);
  125 
  126 static SYSCTL_NODE(_net_inet_tcp, OID_AUTO, hostcache, CTLFLAG_RW, 0,
  127     "TCP Host cache");
  128 
  129 VNET_DEFINE(int, tcp_use_hostcache) = 1;
  130 #define V_tcp_use_hostcache  VNET(tcp_use_hostcache)
  131 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, enable, CTLFLAG_VNET | CTLFLAG_RW,
  132     &VNET_NAME(tcp_use_hostcache), 0,
  133     "Enable the TCP hostcache");
  134 
  135 SYSCTL_UINT(_net_inet_tcp_hostcache, OID_AUTO, cachelimit, CTLFLAG_VNET | CTLFLAG_RDTUN,
  136     &VNET_NAME(tcp_hostcache.cache_limit), 0,
  137     "Overall entry limit for hostcache");
  138 
  139 SYSCTL_UINT(_net_inet_tcp_hostcache, OID_AUTO, hashsize, CTLFLAG_VNET | CTLFLAG_RDTUN,
  140     &VNET_NAME(tcp_hostcache.hashsize), 0,
  141     "Size of TCP hostcache hashtable");
  142 
  143 SYSCTL_UINT(_net_inet_tcp_hostcache, OID_AUTO, bucketlimit,
  144     CTLFLAG_VNET | CTLFLAG_RDTUN, &VNET_NAME(tcp_hostcache.bucket_limit), 0,
  145     "Per-bucket hash limit for hostcache");
  146 
  147 SYSCTL_UINT(_net_inet_tcp_hostcache, OID_AUTO, count, CTLFLAG_VNET | CTLFLAG_RD,
  148      &VNET_NAME(tcp_hostcache.cache_count), 0,
  149     "Current number of entries in hostcache");
  150 
  151 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, expire, CTLFLAG_VNET | CTLFLAG_RW,
  152     &VNET_NAME(tcp_hostcache.expire), 0,
  153     "Expire time of TCP hostcache entries");
  154 
  155 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, prune, CTLFLAG_VNET | CTLFLAG_RW,
  156     &VNET_NAME(tcp_hostcache.prune), 0,
  157     "Time between purge runs");
  158 
  159 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, purge, CTLFLAG_VNET | CTLFLAG_RW,
  160     &VNET_NAME(tcp_hostcache.purgeall), 0,
  161     "Expire all entires on next purge run");
  162 
  163 SYSCTL_PROC(_net_inet_tcp_hostcache, OID_AUTO, list,
  164     CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_SKIP, 0, 0,
  165     sysctl_tcp_hc_list, "A", "List of all hostcache entries");
  166 
  167 SYSCTL_PROC(_net_inet_tcp_hostcache, OID_AUTO, purgenow,
  168     CTLTYPE_INT | CTLFLAG_RW, NULL, 0,
  169     sysctl_tcp_hc_purgenow, "I", "Immediately purge all entries");
  170 
  171 static MALLOC_DEFINE(M_HOSTCACHE, "hostcache", "TCP hostcache");
  172 
  173 #define HOSTCACHE_HASH(ip) \
  174         (((ip)->s_addr ^ ((ip)->s_addr >> 7) ^ ((ip)->s_addr >> 17)) &  \
  175           V_tcp_hostcache.hashmask)
  176 
  177 /* XXX: What is the recommended hash to get good entropy for IPv6 addresses? */
  178 #define HOSTCACHE_HASH6(ip6)                            \
  179         (((ip6)->s6_addr32[0] ^                         \
  180           (ip6)->s6_addr32[1] ^                         \
  181           (ip6)->s6_addr32[2] ^                         \
  182           (ip6)->s6_addr32[3]) &                        \
  183          V_tcp_hostcache.hashmask)
  184 
  185 #define THC_LOCK(lp)            mtx_lock(lp)
  186 #define THC_UNLOCK(lp)          mtx_unlock(lp)
  187 
  188 void
  189 tcp_hc_init(void)
  190 {
  191         u_int cache_limit;
  192         int i;
  193 
  194         /*
  195          * Initialize hostcache structures.
  196          */
  197         V_tcp_hostcache.cache_count = 0;
  198         V_tcp_hostcache.hashsize = TCP_HOSTCACHE_HASHSIZE;
  199         V_tcp_hostcache.bucket_limit = TCP_HOSTCACHE_BUCKETLIMIT;
  200         V_tcp_hostcache.expire = TCP_HOSTCACHE_EXPIRE;
  201         V_tcp_hostcache.prune = TCP_HOSTCACHE_PRUNE;
  202 
  203         TUNABLE_INT_FETCH("net.inet.tcp.hostcache.hashsize",
  204             &V_tcp_hostcache.hashsize);
  205         if (!powerof2(V_tcp_hostcache.hashsize)) {
  206                 printf("WARNING: hostcache hash size is not a power of 2.\n");
  207                 V_tcp_hostcache.hashsize = TCP_HOSTCACHE_HASHSIZE; /* default */
  208         }
  209         V_tcp_hostcache.hashmask = V_tcp_hostcache.hashsize - 1;
  210 
  211         TUNABLE_INT_FETCH("net.inet.tcp.hostcache.bucketlimit",
  212             &V_tcp_hostcache.bucket_limit);
  213 
  214         cache_limit = V_tcp_hostcache.hashsize * V_tcp_hostcache.bucket_limit;
  215         V_tcp_hostcache.cache_limit = cache_limit;
  216         TUNABLE_INT_FETCH("net.inet.tcp.hostcache.cachelimit",
  217             &V_tcp_hostcache.cache_limit);
  218         if (V_tcp_hostcache.cache_limit > cache_limit)
  219                 V_tcp_hostcache.cache_limit = cache_limit;
  220 
  221         /*
  222          * Allocate the hash table.
  223          */
  224         V_tcp_hostcache.hashbase = (struct hc_head *)
  225             malloc(V_tcp_hostcache.hashsize * sizeof(struct hc_head),
  226                    M_HOSTCACHE, M_WAITOK | M_ZERO);
  227 
  228         /*
  229          * Initialize the hash buckets.
  230          */
  231         for (i = 0; i < V_tcp_hostcache.hashsize; i++) {
  232                 TAILQ_INIT(&V_tcp_hostcache.hashbase[i].hch_bucket);
  233                 V_tcp_hostcache.hashbase[i].hch_length = 0;
  234                 mtx_init(&V_tcp_hostcache.hashbase[i].hch_mtx, "tcp_hc_entry",
  235                           NULL, MTX_DEF);
  236         }
  237 
  238         /*
  239          * Allocate the hostcache entries.
  240          */
  241         V_tcp_hostcache.zone =
  242             uma_zcreate("hostcache", sizeof(struct hc_metrics),
  243             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
  244         uma_zone_set_max(V_tcp_hostcache.zone, V_tcp_hostcache.cache_limit);
  245 
  246         /*
  247          * Set up periodic cache cleanup.
  248          */
  249         callout_init(&V_tcp_hc_callout, 1);
  250         callout_reset(&V_tcp_hc_callout, V_tcp_hostcache.prune * hz,
  251             tcp_hc_purge, curvnet);
  252 }
  253 
  254 #ifdef VIMAGE
  255 void
  256 tcp_hc_destroy(void)
  257 {
  258         int i;
  259 
  260         callout_drain(&V_tcp_hc_callout);
  261 
  262         /* Purge all hc entries. */
  263         tcp_hc_purge_internal(1);
  264 
  265         /* Free the uma zone and the allocated hash table. */
  266         uma_zdestroy(V_tcp_hostcache.zone);
  267 
  268         for (i = 0; i < V_tcp_hostcache.hashsize; i++)
  269                 mtx_destroy(&V_tcp_hostcache.hashbase[i].hch_mtx);
  270         free(V_tcp_hostcache.hashbase, M_HOSTCACHE);
  271 }
  272 #endif
  273 
  274 /*
  275  * Internal function: look up an entry in the hostcache or return NULL.
  276  *
  277  * If an entry has been returned, the caller becomes responsible for
  278  * unlocking the bucket row after he is done reading/modifying the entry.
  279  */
  280 static struct hc_metrics *
  281 tcp_hc_lookup(struct in_conninfo *inc)
  282 {
  283         int hash;
  284         struct hc_head *hc_head;
  285         struct hc_metrics *hc_entry;
  286 
  287         if (!V_tcp_use_hostcache)
  288                 return NULL;
  289 
  290         KASSERT(inc != NULL, ("tcp_hc_lookup with NULL in_conninfo pointer"));
  291 
  292         /*
  293          * Hash the foreign ip address.
  294          */
  295         if (inc->inc_flags & INC_ISIPV6)
  296                 hash = HOSTCACHE_HASH6(&inc->inc6_faddr);
  297         else
  298                 hash = HOSTCACHE_HASH(&inc->inc_faddr);
  299 
  300         hc_head = &V_tcp_hostcache.hashbase[hash];
  301 
  302         /*
  303          * Acquire lock for this bucket row; we release the lock if we don't
  304          * find an entry, otherwise the caller has to unlock after he is
  305          * done.
  306          */
  307         THC_LOCK(&hc_head->hch_mtx);
  308 
  309         /*
  310          * Iterate through entries in bucket row looking for a match.
  311          */
  312         TAILQ_FOREACH(hc_entry, &hc_head->hch_bucket, rmx_q) {
  313                 if (inc->inc_flags & INC_ISIPV6) {
  314                         /* XXX: check ip6_zoneid */
  315                         if (memcmp(&inc->inc6_faddr, &hc_entry->ip6,
  316                             sizeof(inc->inc6_faddr)) == 0)
  317                                 return hc_entry;
  318                 } else {
  319                         if (memcmp(&inc->inc_faddr, &hc_entry->ip4,
  320                             sizeof(inc->inc_faddr)) == 0)
  321                                 return hc_entry;
  322                 }
  323         }
  324 
  325         /*
  326          * We were unsuccessful and didn't find anything.
  327          */
  328         THC_UNLOCK(&hc_head->hch_mtx);
  329         return NULL;
  330 }
  331 
  332 /*
  333  * Internal function: insert an entry into the hostcache or return NULL if
  334  * unable to allocate a new one.
  335  *
  336  * If an entry has been returned, the caller becomes responsible for
  337  * unlocking the bucket row after he is done reading/modifying the entry.
  338  */
  339 static struct hc_metrics *
  340 tcp_hc_insert(struct in_conninfo *inc)
  341 {
  342         int hash;
  343         struct hc_head *hc_head;
  344         struct hc_metrics *hc_entry;
  345 
  346         if (!V_tcp_use_hostcache)
  347                 return NULL;
  348 
  349         KASSERT(inc != NULL, ("tcp_hc_insert with NULL in_conninfo pointer"));
  350 
  351         /*
  352          * Hash the foreign ip address.
  353          */
  354         if (inc->inc_flags & INC_ISIPV6)
  355                 hash = HOSTCACHE_HASH6(&inc->inc6_faddr);
  356         else
  357                 hash = HOSTCACHE_HASH(&inc->inc_faddr);
  358 
  359         hc_head = &V_tcp_hostcache.hashbase[hash];
  360 
  361         /*
  362          * Acquire lock for this bucket row; we release the lock if we don't
  363          * find an entry, otherwise the caller has to unlock after he is
  364          * done.
  365          */
  366         THC_LOCK(&hc_head->hch_mtx);
  367 
  368         /*
  369          * If the bucket limit is reached, reuse the least-used element.
  370          */
  371         if (hc_head->hch_length >= V_tcp_hostcache.bucket_limit ||
  372             V_tcp_hostcache.cache_count >= V_tcp_hostcache.cache_limit) {
  373                 hc_entry = TAILQ_LAST(&hc_head->hch_bucket, hc_qhead);
  374                 /*
  375                  * At first we were dropping the last element, just to
  376                  * reacquire it in the next two lines again, which isn't very
  377                  * efficient.  Instead just reuse the least used element.
  378                  * We may drop something that is still "in-use" but we can be
  379                  * "lossy".
  380                  * Just give up if this bucket row is empty and we don't have
  381                  * anything to replace.
  382                  */
  383                 if (hc_entry == NULL) {
  384                         THC_UNLOCK(&hc_head->hch_mtx);
  385                         return NULL;
  386                 }
  387                 TAILQ_REMOVE(&hc_head->hch_bucket, hc_entry, rmx_q);
  388                 V_tcp_hostcache.hashbase[hash].hch_length--;
  389                 V_tcp_hostcache.cache_count--;
  390                 TCPSTAT_INC(tcps_hc_bucketoverflow);
  391 #if 0
  392                 uma_zfree(V_tcp_hostcache.zone, hc_entry);
  393 #endif
  394         } else {
  395                 /*
  396                  * Allocate a new entry, or balk if not possible.
  397                  */
  398                 hc_entry = uma_zalloc(V_tcp_hostcache.zone, M_NOWAIT);
  399                 if (hc_entry == NULL) {
  400                         THC_UNLOCK(&hc_head->hch_mtx);
  401                         return NULL;
  402                 }
  403         }
  404 
  405         /*
  406          * Initialize basic information of hostcache entry.
  407          */
  408         bzero(hc_entry, sizeof(*hc_entry));
  409         if (inc->inc_flags & INC_ISIPV6) {
  410                 hc_entry->ip6 = inc->inc6_faddr;
  411                 hc_entry->ip6_zoneid = inc->inc6_zoneid;
  412         } else
  413                 hc_entry->ip4 = inc->inc_faddr;
  414         hc_entry->rmx_head = hc_head;
  415         hc_entry->rmx_expire = V_tcp_hostcache.expire;
  416 
  417         /*
  418          * Put it upfront.
  419          */
  420         TAILQ_INSERT_HEAD(&hc_head->hch_bucket, hc_entry, rmx_q);
  421         V_tcp_hostcache.hashbase[hash].hch_length++;
  422         V_tcp_hostcache.cache_count++;
  423         TCPSTAT_INC(tcps_hc_added);
  424 
  425         return hc_entry;
  426 }
  427 
  428 /*
  429  * External function: look up an entry in the hostcache and fill out the
  430  * supplied TCP metrics structure.  Fills in NULL when no entry was found or
  431  * a value is not set.
  432  */
  433 void
  434 tcp_hc_get(struct in_conninfo *inc, struct hc_metrics_lite *hc_metrics_lite)
  435 {
  436         struct hc_metrics *hc_entry;
  437 
  438         if (!V_tcp_use_hostcache)
  439                 return;
  440 
  441         /*
  442          * Find the right bucket.
  443          */
  444         hc_entry = tcp_hc_lookup(inc);
  445 
  446         /*
  447          * If we don't have an existing object.
  448          */
  449         if (hc_entry == NULL) {
  450                 bzero(hc_metrics_lite, sizeof(*hc_metrics_lite));
  451                 return;
  452         }
  453         hc_entry->rmx_hits++;
  454         hc_entry->rmx_expire = V_tcp_hostcache.expire; /* start over again */
  455 
  456         hc_metrics_lite->rmx_mtu = hc_entry->rmx_mtu;
  457         hc_metrics_lite->rmx_ssthresh = hc_entry->rmx_ssthresh;
  458         hc_metrics_lite->rmx_rtt = hc_entry->rmx_rtt;
  459         hc_metrics_lite->rmx_rttvar = hc_entry->rmx_rttvar;
  460         hc_metrics_lite->rmx_cwnd = hc_entry->rmx_cwnd;
  461         hc_metrics_lite->rmx_sendpipe = hc_entry->rmx_sendpipe;
  462         hc_metrics_lite->rmx_recvpipe = hc_entry->rmx_recvpipe;
  463 
  464         /*
  465          * Unlock bucket row.
  466          */
  467         THC_UNLOCK(&hc_entry->rmx_head->hch_mtx);
  468 }
  469 
  470 /*
  471  * External function: look up an entry in the hostcache and return the
  472  * discovered path MTU.  Returns 0 if no entry is found or value is not
  473  * set.
  474  */
  475 u_long
  476 tcp_hc_getmtu(struct in_conninfo *inc)
  477 {
  478         struct hc_metrics *hc_entry;
  479         u_long mtu;
  480 
  481         if (!V_tcp_use_hostcache)
  482                 return 0;
  483 
  484         hc_entry = tcp_hc_lookup(inc);
  485         if (hc_entry == NULL) {
  486                 return 0;
  487         }
  488         hc_entry->rmx_hits++;
  489         hc_entry->rmx_expire = V_tcp_hostcache.expire; /* start over again */
  490 
  491         mtu = hc_entry->rmx_mtu;
  492         THC_UNLOCK(&hc_entry->rmx_head->hch_mtx);
  493         return mtu;
  494 }
  495 
  496 /*
  497  * External function: update the MTU value of an entry in the hostcache.
  498  * Creates a new entry if none was found.
  499  */
  500 void
  501 tcp_hc_updatemtu(struct in_conninfo *inc, u_long mtu)
  502 {
  503         struct hc_metrics *hc_entry;
  504 
  505         if (!V_tcp_use_hostcache)
  506                 return;
  507 
  508         /*
  509          * Find the right bucket.
  510          */
  511         hc_entry = tcp_hc_lookup(inc);
  512 
  513         /*
  514          * If we don't have an existing object, try to insert a new one.
  515          */
  516         if (hc_entry == NULL) {
  517                 hc_entry = tcp_hc_insert(inc);
  518                 if (hc_entry == NULL)
  519                         return;
  520         }
  521         hc_entry->rmx_updates++;
  522         hc_entry->rmx_expire = V_tcp_hostcache.expire; /* start over again */
  523 
  524         hc_entry->rmx_mtu = mtu;
  525 
  526         /*
  527          * Put it upfront so we find it faster next time.
  528          */
  529         TAILQ_REMOVE(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q);
  530         TAILQ_INSERT_HEAD(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q);
  531 
  532         /*
  533          * Unlock bucket row.
  534          */
  535         THC_UNLOCK(&hc_entry->rmx_head->hch_mtx);
  536 }
  537 
  538 /*
  539  * External function: update the TCP metrics of an entry in the hostcache.
  540  * Creates a new entry if none was found.
  541  */
  542 void
  543 tcp_hc_update(struct in_conninfo *inc, struct hc_metrics_lite *hcml)
  544 {
  545         struct hc_metrics *hc_entry;
  546 
  547         if (!V_tcp_use_hostcache)
  548                 return;
  549 
  550         hc_entry = tcp_hc_lookup(inc);
  551         if (hc_entry == NULL) {
  552                 hc_entry = tcp_hc_insert(inc);
  553                 if (hc_entry == NULL)
  554                         return;
  555         }
  556         hc_entry->rmx_updates++;
  557         hc_entry->rmx_expire = V_tcp_hostcache.expire; /* start over again */
  558 
  559         if (hcml->rmx_rtt != 0) {
  560                 if (hc_entry->rmx_rtt == 0)
  561                         hc_entry->rmx_rtt = hcml->rmx_rtt;
  562                 else
  563                         hc_entry->rmx_rtt =
  564                             (hc_entry->rmx_rtt + hcml->rmx_rtt) / 2;
  565                 TCPSTAT_INC(tcps_cachedrtt);
  566         }
  567         if (hcml->rmx_rttvar != 0) {
  568                 if (hc_entry->rmx_rttvar == 0)
  569                         hc_entry->rmx_rttvar = hcml->rmx_rttvar;
  570                 else
  571                         hc_entry->rmx_rttvar =
  572                             (hc_entry->rmx_rttvar + hcml->rmx_rttvar) / 2;
  573                 TCPSTAT_INC(tcps_cachedrttvar);
  574         }
  575         if (hcml->rmx_ssthresh != 0) {
  576                 if (hc_entry->rmx_ssthresh == 0)
  577                         hc_entry->rmx_ssthresh = hcml->rmx_ssthresh;
  578                 else
  579                         hc_entry->rmx_ssthresh =
  580                             (hc_entry->rmx_ssthresh + hcml->rmx_ssthresh) / 2;
  581                 TCPSTAT_INC(tcps_cachedssthresh);
  582         }
  583         if (hcml->rmx_cwnd != 0) {
  584                 if (hc_entry->rmx_cwnd == 0)
  585                         hc_entry->rmx_cwnd = hcml->rmx_cwnd;
  586                 else
  587                         hc_entry->rmx_cwnd =
  588                             (hc_entry->rmx_cwnd + hcml->rmx_cwnd) / 2;
  589                 /* TCPSTAT_INC(tcps_cachedcwnd); */
  590         }
  591         if (hcml->rmx_sendpipe != 0) {
  592                 if (hc_entry->rmx_sendpipe == 0)
  593                         hc_entry->rmx_sendpipe = hcml->rmx_sendpipe;
  594                 else
  595                         hc_entry->rmx_sendpipe =
  596                             (hc_entry->rmx_sendpipe + hcml->rmx_sendpipe) /2;
  597                 /* TCPSTAT_INC(tcps_cachedsendpipe); */
  598         }
  599         if (hcml->rmx_recvpipe != 0) {
  600                 if (hc_entry->rmx_recvpipe == 0)
  601                         hc_entry->rmx_recvpipe = hcml->rmx_recvpipe;
  602                 else
  603                         hc_entry->rmx_recvpipe =
  604                             (hc_entry->rmx_recvpipe + hcml->rmx_recvpipe) /2;
  605                 /* TCPSTAT_INC(tcps_cachedrecvpipe); */
  606         }
  607 
  608         TAILQ_REMOVE(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q);
  609         TAILQ_INSERT_HEAD(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q);
  610         THC_UNLOCK(&hc_entry->rmx_head->hch_mtx);
  611 }
  612 
  613 /*
  614  * Sysctl function: prints the list and values of all hostcache entries in
  615  * unsorted order.
  616  */
  617 static int
  618 sysctl_tcp_hc_list(SYSCTL_HANDLER_ARGS)
  619 {
  620         const int linesize = 128;
  621         struct sbuf sb;
  622         int i, error;
  623         struct hc_metrics *hc_entry;
  624         char ip4buf[INET_ADDRSTRLEN];
  625 #ifdef INET6
  626         char ip6buf[INET6_ADDRSTRLEN];
  627 #endif
  628 
  629         if (jailed_without_vnet(curthread->td_ucred) != 0)
  630                 return (EPERM);
  631 
  632         sbuf_new(&sb, NULL, linesize * (V_tcp_hostcache.cache_count + 1),
  633                 SBUF_INCLUDENUL);
  634 
  635         sbuf_printf(&sb,
  636                 "\nIP address        MTU  SSTRESH      RTT   RTTVAR "
  637                 "    CWND SENDPIPE RECVPIPE HITS  UPD  EXP\n");
  638 
  639 #define msec(u) (((u) + 500) / 1000)
  640         for (i = 0; i < V_tcp_hostcache.hashsize; i++) {
  641                 THC_LOCK(&V_tcp_hostcache.hashbase[i].hch_mtx);
  642                 TAILQ_FOREACH(hc_entry, &V_tcp_hostcache.hashbase[i].hch_bucket,
  643                               rmx_q) {
  644                         sbuf_printf(&sb,
  645                             "%-15s %5lu %8lu %6lums %6lums %8lu %8lu %8lu %4lu "
  646                             "%4lu %4i\n",
  647                             hc_entry->ip4.s_addr ?
  648                                 inet_ntoa_r(hc_entry->ip4, ip4buf) :
  649 #ifdef INET6
  650                                 ip6_sprintf(ip6buf, &hc_entry->ip6),
  651 #else
  652                                 "IPv6?",
  653 #endif
  654                             hc_entry->rmx_mtu,
  655                             hc_entry->rmx_ssthresh,
  656                             msec(hc_entry->rmx_rtt *
  657                                 (RTM_RTTUNIT / (hz * TCP_RTT_SCALE))),
  658                             msec(hc_entry->rmx_rttvar *
  659                                 (RTM_RTTUNIT / (hz * TCP_RTTVAR_SCALE))),
  660                             hc_entry->rmx_cwnd,
  661                             hc_entry->rmx_sendpipe,
  662                             hc_entry->rmx_recvpipe,
  663                             hc_entry->rmx_hits,
  664                             hc_entry->rmx_updates,
  665                             hc_entry->rmx_expire);
  666                 }
  667                 THC_UNLOCK(&V_tcp_hostcache.hashbase[i].hch_mtx);
  668         }
  669 #undef msec
  670         error = sbuf_finish(&sb);
  671         if (error == 0)
  672                 error = SYSCTL_OUT(req, sbuf_data(&sb), sbuf_len(&sb));
  673         sbuf_delete(&sb);
  674         return(error);
  675 }
  676 
  677 /*
  678  * Caller has to make sure the curvnet is set properly.
  679  */
  680 static void
  681 tcp_hc_purge_internal(int all)
  682 {
  683         struct hc_metrics *hc_entry, *hc_next;
  684         int i;
  685 
  686         for (i = 0; i < V_tcp_hostcache.hashsize; i++) {
  687                 THC_LOCK(&V_tcp_hostcache.hashbase[i].hch_mtx);
  688                 TAILQ_FOREACH_SAFE(hc_entry,
  689                     &V_tcp_hostcache.hashbase[i].hch_bucket, rmx_q, hc_next) {
  690                         if (all || hc_entry->rmx_expire <= 0) {
  691                                 TAILQ_REMOVE(&V_tcp_hostcache.hashbase[i].hch_bucket,
  692                                               hc_entry, rmx_q);
  693                                 uma_zfree(V_tcp_hostcache.zone, hc_entry);
  694                                 V_tcp_hostcache.hashbase[i].hch_length--;
  695                                 V_tcp_hostcache.cache_count--;
  696                         } else
  697                                 hc_entry->rmx_expire -= V_tcp_hostcache.prune;
  698                 }
  699                 THC_UNLOCK(&V_tcp_hostcache.hashbase[i].hch_mtx);
  700         }
  701 }
  702 
  703 /*
  704  * Expire and purge (old|all) entries in the tcp_hostcache.  Runs
  705  * periodically from the callout.
  706  */
  707 static void
  708 tcp_hc_purge(void *arg)
  709 {
  710         CURVNET_SET((struct vnet *) arg);
  711         int all = 0;
  712 
  713         if (V_tcp_hostcache.purgeall) {
  714                 all = 1;
  715                 V_tcp_hostcache.purgeall = 0;
  716         }
  717 
  718         tcp_hc_purge_internal(all);
  719 
  720         callout_reset(&V_tcp_hc_callout, V_tcp_hostcache.prune * hz,
  721             tcp_hc_purge, arg);
  722         CURVNET_RESTORE();
  723 }
  724 
  725 /*
  726  * Expire and purge all entries in hostcache immediately.
  727  */
  728 static int
  729 sysctl_tcp_hc_purgenow(SYSCTL_HANDLER_ARGS)
  730 {
  731         int error, val;
  732 
  733         val = 0;
  734         error = sysctl_handle_int(oidp, &val, 0, req);
  735         if (error || !req->newptr)
  736                 return (error);
  737 
  738         tcp_hc_purge_internal(1);
  739 
  740         callout_reset(&V_tcp_hc_callout, V_tcp_hostcache.prune * hz,
  741             tcp_hc_purge, curvnet);
  742 
  743         return (0);
  744 }
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FreeBSD/Linux Kernel Cross Reference sys/netinet/tcp_hostcache.c

FreeBSD/Linux Kernel Cross Reference
sys/netinet/tcp_hostcache.c
