/*- * Copyright (c) 2002 Andre Oppermann, Internet Business Solutions AG * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. The name of the author may not be used to endorse or promote * products derived from this software without specific prior written * permission. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ /* * The tcp_hostcache moves the tcp-specific cached metrics from the routing * table to a dedicated structure indexed by the remote IP address. It keeps * information on the measured TCP parameters of past TCP sessions to allow * better initial start values to be used with later connections to/from the * same source. Depending on the network parameters (delay, bandwidth, max * MTU, congestion window) between local and remote sites, this can lead to * significant speed-ups for new TCP connections after the first one. * * Due to the tcp_hostcache, all TCP-specific metrics information in the * routing table has been removed. The inpcb no longer keeps a pointer to * the routing entry, and protocol-initiated route cloning has been removed * as well. With these changes, the routing table has gone back to being * more lightwight and only carries information related to packet forwarding. * * tcp_hostcache is designed for multiple concurrent access in SMP * environments and high contention. All bucket rows have their own lock and * thus multiple lookups and modifies can be done at the same time as long as * they are in different bucket rows. If a request for insertion of a new * record can't be satisfied, it simply returns an empty structure. Nobody * and nothing outside of tcp_hostcache.c will ever point directly to any * entry in the tcp_hostcache. All communication is done in an * object-oriented way and only functions of tcp_hostcache will manipulate * hostcache entries. Otherwise, we are unable to achieve good behaviour in * concurrent access situations. Since tcp_hostcache is only caching * information, there are no fatal consequences if we either can't satisfy * any particular request or have to drop/overwrite an existing entry because * of bucket limit memory constrains. */ /* * Many thanks to jlemon for basic structure of tcp_syncache which is being * followed here. */ #include __FBSDID("$FreeBSD$"); #include "opt_inet6.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef INET6 #include #include #endif #include #include #ifdef INET6 #include #endif #include TAILQ_HEAD(hc_qhead, hc_metrics); struct hc_head { struct hc_qhead hch_bucket; u_int hch_length; struct mtx hch_mtx; }; struct hc_metrics { /* housekeeping */ TAILQ_ENTRY(hc_metrics) rmx_q; struct hc_head *rmx_head; /* head of bucket tail queue */ struct in_addr ip4; /* IP address */ struct in6_addr ip6; /* IP6 address */ /* endpoint specific values for TCP */ u_long rmx_mtu; /* MTU for this path */ u_long rmx_ssthresh; /* outbound gateway buffer limit */ u_long rmx_rtt; /* estimated round trip time */ u_long rmx_rttvar; /* estimated rtt variance */ u_long rmx_bandwidth; /* estimated bandwidth */ u_long rmx_cwnd; /* congestion window */ u_long rmx_sendpipe; /* outbound delay-bandwidth product */ u_long rmx_recvpipe; /* inbound delay-bandwidth product */ /* TCP hostcache internal data */ int rmx_expire; /* lifetime for object */ u_long rmx_hits; /* number of hits */ u_long rmx_updates; /* number of updates */ }; /* Arbitrary values */ #define TCP_HOSTCACHE_HASHSIZE 512 #define TCP_HOSTCACHE_BUCKETLIMIT 30 #define TCP_HOSTCACHE_EXPIRE 60*60 /* one hour */ #define TCP_HOSTCACHE_PRUNE 5*60 /* every 5 minutes */ struct tcp_hostcache { struct hc_head *hashbase; uma_zone_t zone; u_int hashsize; u_int hashmask; u_int bucket_limit; u_int cache_count; u_int cache_limit; int expire; int prune; int purgeall; }; static struct tcp_hostcache tcp_hostcache; static struct callout tcp_hc_callout; static struct hc_metrics *tcp_hc_lookup(struct in_conninfo *); static struct hc_metrics *tcp_hc_insert(struct in_conninfo *); static int sysctl_tcp_hc_list(SYSCTL_HANDLER_ARGS); static void tcp_hc_purge(void *); SYSCTL_NODE(_net_inet_tcp, OID_AUTO, hostcache, CTLFLAG_RW, 0, "TCP Host cache"); SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, cachelimit, CTLFLAG_RDTUN, &tcp_hostcache.cache_limit, 0, "Overall entry limit for hostcache"); SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, hashsize, CTLFLAG_RDTUN, &tcp_hostcache.hashsize, 0, "Size of TCP hostcache hashtable"); SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, bucketlimit, CTLFLAG_RDTUN, &tcp_hostcache.bucket_limit, 0, "Per-bucket hash limit for hostcache"); SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, count, CTLFLAG_RD, &tcp_hostcache.cache_count, 0, "Current number of entries in hostcache"); SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, expire, CTLFLAG_RW, &tcp_hostcache.expire, 0, "Expire time of TCP hostcache entries"); SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, prune, CTLFLAG_RW, &tcp_hostcache.prune, 0, "Time between purge runs"); SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, purge, CTLFLAG_RW, &tcp_hostcache.purgeall, 0, "Expire all entires on next purge run"); SYSCTL_PROC(_net_inet_tcp_hostcache, OID_AUTO, list, CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_SKIP, 0, 0, sysctl_tcp_hc_list, "A", "List of all hostcache entries"); static MALLOC_DEFINE(M_HOSTCACHE, "hostcache", "TCP hostcache"); #define HOSTCACHE_HASH(ip) \ (((ip)->s_addr ^ ((ip)->s_addr >> 7) ^ ((ip)->s_addr >> 17)) & \ tcp_hostcache.hashmask) /* XXX: What is the recommended hash to get good entropy for IPv6 addresses? */ #define HOSTCACHE_HASH6(ip6) \ (((ip6)->s6_addr32[0] ^ \ (ip6)->s6_addr32[1] ^ \ (ip6)->s6_addr32[2] ^ \ (ip6)->s6_addr32[3]) & \ tcp_hostcache.hashmask) #define THC_LOCK(lp) mtx_lock(lp) #define THC_UNLOCK(lp) mtx_unlock(lp) void tcp_hc_init(void) { int i; /* * Initialize hostcache structures. */ tcp_hostcache.cache_count = 0; tcp_hostcache.hashsize = TCP_HOSTCACHE_HASHSIZE; tcp_hostcache.bucket_limit = TCP_HOSTCACHE_BUCKETLIMIT; tcp_hostcache.cache_limit = tcp_hostcache.hashsize * tcp_hostcache.bucket_limit; tcp_hostcache.expire = TCP_HOSTCACHE_EXPIRE; tcp_hostcache.prune = TCP_HOSTCACHE_PRUNE; TUNABLE_INT_FETCH("net.inet.tcp.hostcache.hashsize", &tcp_hostcache.hashsize); TUNABLE_INT_FETCH("net.inet.tcp.hostcache.cachelimit", &tcp_hostcache.cache_limit); TUNABLE_INT_FETCH("net.inet.tcp.hostcache.bucketlimit", &tcp_hostcache.bucket_limit); if (!powerof2(tcp_hostcache.hashsize)) { printf("WARNING: hostcache hash size is not a power of 2.\n"); tcp_hostcache.hashsize = TCP_HOSTCACHE_HASHSIZE; /* default */ } tcp_hostcache.hashmask = tcp_hostcache.hashsize - 1; /* * Allocate the hash table. */ tcp_hostcache.hashbase = (struct hc_head *) malloc(tcp_hostcache.hashsize * sizeof(struct hc_head), M_HOSTCACHE, M_WAITOK | M_ZERO); /* * Initialize the hash buckets. */ for (i = 0; i < tcp_hostcache.hashsize; i++) { TAILQ_INIT(&tcp_hostcache.hashbase[i].hch_bucket); tcp_hostcache.hashbase[i].hch_length = 0; mtx_init(&tcp_hostcache.hashbase[i].hch_mtx, "tcp_hc_entry", NULL, MTX_DEF); } /* * Allocate the hostcache entries. */ tcp_hostcache.zone = uma_zcreate("hostcache", sizeof(struct hc_metrics), NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); uma_zone_set_max(tcp_hostcache.zone, tcp_hostcache.cache_limit); /* * Set up periodic cache cleanup. */ callout_init(&tcp_hc_callout, CALLOUT_MPSAFE); callout_reset(&tcp_hc_callout, tcp_hostcache.prune * hz, tcp_hc_purge, 0); } /* * Internal function: look up an entry in the hostcache or return NULL. * * If an entry has been returned, the caller becomes responsible for * unlocking the bucket row after he is done reading/modifying the entry. */ static struct hc_metrics * tcp_hc_lookup(struct in_conninfo *inc) { int hash; struct hc_head *hc_head; struct hc_metrics *hc_entry; KASSERT(inc != NULL, ("tcp_hc_lookup with NULL in_conninfo pointer")); /* * Hash the foreign ip address. */ if (inc->inc_flags & INC_ISIPV6) hash = HOSTCACHE_HASH6(&inc->inc6_faddr); else hash = HOSTCACHE_HASH(&inc->inc_faddr); hc_head = &tcp_hostcache.hashbase[hash]; /* * Acquire lock for this bucket row; we release the lock if we don't * find an entry, otherwise the caller has to unlock after he is * done. */ THC_LOCK(&hc_head->hch_mtx); /* * Iterate through entries in bucket row looking for a match. */ TAILQ_FOREACH(hc_entry, &hc_head->hch_bucket, rmx_q) { if (inc->inc_flags & INC_ISIPV6) { if (memcmp(&inc->inc6_faddr, &hc_entry->ip6, sizeof(inc->inc6_faddr)) == 0) return hc_entry; } else { if (memcmp(&inc->inc_faddr, &hc_entry->ip4, sizeof(inc->inc_faddr)) == 0) return hc_entry; } } /* * We were unsuccessful and didn't find anything. */ THC_UNLOCK(&hc_head->hch_mtx); return NULL; } /* * Internal function: insert an entry into the hostcache or return NULL if * unable to allocate a new one. * * If an entry has been returned, the caller becomes responsible for * unlocking the bucket row after he is done reading/modifying the entry. */ static struct hc_metrics * tcp_hc_insert(struct in_conninfo *inc) { int hash; struct hc_head *hc_head; struct hc_metrics *hc_entry; KASSERT(inc != NULL, ("tcp_hc_insert with NULL in_conninfo pointer")); /* * Hash the foreign ip address. */ if (inc->inc_flags & INC_ISIPV6) hash = HOSTCACHE_HASH6(&inc->inc6_faddr); else hash = HOSTCACHE_HASH(&inc->inc_faddr); hc_head = &tcp_hostcache.hashbase[hash]; /* * Acquire lock for this bucket row; we release the lock if we don't * find an entry, otherwise the caller has to unlock after he is * done. */ THC_LOCK(&hc_head->hch_mtx); /* * If the bucket limit is reached, reuse the least-used element. */ if (hc_head->hch_length >= tcp_hostcache.bucket_limit || tcp_hostcache.cache_count >= tcp_hostcache.cache_limit) { hc_entry = TAILQ_LAST(&hc_head->hch_bucket, hc_qhead); /* * At first we were dropping the last element, just to * reacquire it in the next two lines again, which isn't very * efficient. Instead just reuse the least used element. * We may drop something that is still "in-use" but we can be * "lossy". * Just give up if this bucket row is empty and we don't have * anything to replace. */ if (hc_entry == NULL) { THC_UNLOCK(&hc_head->hch_mtx); return NULL; } TAILQ_REMOVE(&hc_head->hch_bucket, hc_entry, rmx_q); tcp_hostcache.hashbase[hash].hch_length--; tcp_hostcache.cache_count--; tcpstat.tcps_hc_bucketoverflow++; #if 0 uma_zfree(tcp_hostcache.zone, hc_entry); #endif } else { /* * Allocate a new entry, or balk if not possible. */ hc_entry = uma_zalloc(tcp_hostcache.zone, M_NOWAIT); if (hc_entry == NULL) { THC_UNLOCK(&hc_head->hch_mtx); return NULL; } } /* * Initialize basic information of hostcache entry. */ bzero(hc_entry, sizeof(*hc_entry)); if (inc->inc_flags & INC_ISIPV6) bcopy(&inc->inc6_faddr, &hc_entry->ip6, sizeof(hc_entry->ip6)); else hc_entry->ip4 = inc->inc_faddr; hc_entry->rmx_head = hc_head; hc_entry->rmx_expire = tcp_hostcache.expire; /* * Put it upfront. */ TAILQ_INSERT_HEAD(&hc_head->hch_bucket, hc_entry, rmx_q); tcp_hostcache.hashbase[hash].hch_length++; tcp_hostcache.cache_count++; tcpstat.tcps_hc_added++; return hc_entry; } /* * External function: look up an entry in the hostcache and fill out the * supplied TCP metrics structure. Fills in NULL when no entry was found or * a value is not set. */ void tcp_hc_get(struct in_conninfo *inc, struct hc_metrics_lite *hc_metrics_lite) { struct hc_metrics *hc_entry; /* * Find the right bucket. */ hc_entry = tcp_hc_lookup(inc); /* * If we don't have an existing object. */ if (hc_entry == NULL) { bzero(hc_metrics_lite, sizeof(*hc_metrics_lite)); return; } hc_entry->rmx_hits++; hc_entry->rmx_expire = tcp_hostcache.expire; /* start over again */ hc_metrics_lite->rmx_mtu = hc_entry->rmx_mtu; hc_metrics_lite->rmx_ssthresh = hc_entry->rmx_ssthresh; hc_metrics_lite->rmx_rtt = hc_entry->rmx_rtt; hc_metrics_lite->rmx_rttvar = hc_entry->rmx_rttvar; hc_metrics_lite->rmx_bandwidth = hc_entry->rmx_bandwidth; hc_metrics_lite->rmx_cwnd = hc_entry->rmx_cwnd; hc_metrics_lite->rmx_sendpipe = hc_entry->rmx_sendpipe; hc_metrics_lite->rmx_recvpipe = hc_entry->rmx_recvpipe; /* * Unlock bucket row. */ THC_UNLOCK(&hc_entry->rmx_head->hch_mtx); } /* * External function: look up an entry in the hostcache and return the * discovered path MTU. Returns NULL if no entry is found or value is not * set. */ u_long tcp_hc_getmtu(struct in_conninfo *inc) { struct hc_metrics *hc_entry; u_long mtu; hc_entry = tcp_hc_lookup(inc); if (hc_entry == NULL) { return 0; } hc_entry->rmx_hits++; hc_entry->rmx_expire = tcp_hostcache.expire; /* start over again */ mtu = hc_entry->rmx_mtu; THC_UNLOCK(&hc_entry->rmx_head->hch_mtx); return mtu; } /* * External function: update the MTU value of an entry in the hostcache. * Creates a new entry if none was found. */ void tcp_hc_updatemtu(struct in_conninfo *inc, u_long mtu) { struct hc_metrics *hc_entry; /* * Find the right bucket. */ hc_entry = tcp_hc_lookup(inc); /* * If we don't have an existing object, try to insert a new one. */ if (hc_entry == NULL) { hc_entry = tcp_hc_insert(inc); if (hc_entry == NULL) return; } hc_entry->rmx_updates++; hc_entry->rmx_expire = tcp_hostcache.expire; /* start over again */ hc_entry->rmx_mtu = mtu; /* * Put it upfront so we find it faster next time. */ TAILQ_REMOVE(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q); TAILQ_INSERT_HEAD(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q); /* * Unlock bucket row. */ THC_UNLOCK(&hc_entry->rmx_head->hch_mtx); } /* * External function: update the TCP metrics of an entry in the hostcache. * Creates a new entry if none was found. */ void tcp_hc_update(struct in_conninfo *inc, struct hc_metrics_lite *hcml) { struct hc_metrics *hc_entry; hc_entry = tcp_hc_lookup(inc); if (hc_entry == NULL) { hc_entry = tcp_hc_insert(inc); if (hc_entry == NULL) return; } hc_entry->rmx_updates++; hc_entry->rmx_expire = tcp_hostcache.expire; /* start over again */ if (hcml->rmx_rtt != 0) { if (hc_entry->rmx_rtt == 0) hc_entry->rmx_rtt = hcml->rmx_rtt; else hc_entry->rmx_rtt = (hc_entry->rmx_rtt + hcml->rmx_rtt) / 2; tcpstat.tcps_cachedrtt++; } if (hcml->rmx_rttvar != 0) { if (hc_entry->rmx_rttvar == 0) hc_entry->rmx_rttvar = hcml->rmx_rttvar; else hc_entry->rmx_rttvar = (hc_entry->rmx_rttvar + hcml->rmx_rttvar) / 2; tcpstat.tcps_cachedrttvar++; } if (hcml->rmx_ssthresh != 0) { if (hc_entry->rmx_ssthresh == 0) hc_entry->rmx_ssthresh = hcml->rmx_ssthresh; else hc_entry->rmx_ssthresh = (hc_entry->rmx_ssthresh + hcml->rmx_ssthresh) / 2; tcpstat.tcps_cachedssthresh++; } if (hcml->rmx_bandwidth != 0) { if (hc_entry->rmx_bandwidth == 0) hc_entry->rmx_bandwidth = hcml->rmx_bandwidth; else hc_entry->rmx_bandwidth = (hc_entry->rmx_bandwidth + hcml->rmx_bandwidth) / 2; /* tcpstat.tcps_cachedbandwidth++; */ } if (hcml->rmx_cwnd != 0) { if (hc_entry->rmx_cwnd == 0) hc_entry->rmx_cwnd = hcml->rmx_cwnd; else hc_entry->rmx_cwnd = (hc_entry->rmx_cwnd + hcml->rmx_cwnd) / 2; /* tcpstat.tcps_cachedcwnd++; */ } if (hcml->rmx_sendpipe != 0) { if (hc_entry->rmx_sendpipe == 0) hc_entry->rmx_sendpipe = hcml->rmx_sendpipe; else hc_entry->rmx_sendpipe = (hc_entry->rmx_sendpipe + hcml->rmx_sendpipe) /2; /* tcpstat.tcps_cachedsendpipe++; */ } if (hcml->rmx_recvpipe != 0) { if (hc_entry->rmx_recvpipe == 0) hc_entry->rmx_recvpipe = hcml->rmx_recvpipe; else hc_entry->rmx_recvpipe = (hc_entry->rmx_recvpipe + hcml->rmx_recvpipe) /2; /* tcpstat.tcps_cachedrecvpipe++; */ } TAILQ_REMOVE(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q); TAILQ_INSERT_HEAD(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q); THC_UNLOCK(&hc_entry->rmx_head->hch_mtx); } /* * Sysctl function: prints the list and values of all hostcache entries in * unsorted order. */ static int sysctl_tcp_hc_list(SYSCTL_HANDLER_ARGS) { int bufsize; int linesize = 128; char *p, *buf; int len, i, error; struct hc_metrics *hc_entry; #ifdef INET6 char ip6buf[INET6_ADDRSTRLEN]; #endif bufsize = linesize * (tcp_hostcache.cache_count + 1); p = buf = (char *)malloc(bufsize, M_TEMP, M_WAITOK|M_ZERO); len = snprintf(p, linesize, "\nIP address MTU SSTRESH RTT RTTVAR BANDWIDTH " " CWND SENDPIPE RECVPIPE HITS UPD EXP\n"); p += len; #define msec(u) (((u) + 500) / 1000) for (i = 0; i < tcp_hostcache.hashsize; i++) { THC_LOCK(&tcp_hostcache.hashbase[i].hch_mtx); TAILQ_FOREACH(hc_entry, &tcp_hostcache.hashbase[i].hch_bucket, rmx_q) { len = snprintf(p, linesize, "%-15s %5lu %8lu %6lums %6lums %9lu %8lu %8lu %8lu " "%4lu %4lu %4i\n", hc_entry->ip4.s_addr ? inet_ntoa(hc_entry->ip4) : #ifdef INET6 ip6_sprintf(ip6buf, &hc_entry->ip6), #else "IPv6?", #endif hc_entry->rmx_mtu, hc_entry->rmx_ssthresh, msec(hc_entry->rmx_rtt * (RTM_RTTUNIT / (hz * TCP_RTT_SCALE))), msec(hc_entry->rmx_rttvar * (RTM_RTTUNIT / (hz * TCP_RTT_SCALE))), hc_entry->rmx_bandwidth * 8, hc_entry->rmx_cwnd, hc_entry->rmx_sendpipe, hc_entry->rmx_recvpipe, hc_entry->rmx_hits, hc_entry->rmx_updates, hc_entry->rmx_expire); p += len; } THC_UNLOCK(&tcp_hostcache.hashbase[i].hch_mtx); } #undef msec error = SYSCTL_OUT(req, buf, p - buf); free(buf, M_TEMP); return(error); } /* * Expire and purge (old|all) entries in the tcp_hostcache. Runs * periodically from the callout. */ static void tcp_hc_purge(void *arg) { struct hc_metrics *hc_entry, *hc_next; int all = (intptr_t)arg; int i; if (tcp_hostcache.purgeall) { all = 1; tcp_hostcache.purgeall = 0; } for (i = 0; i < tcp_hostcache.hashsize; i++) { THC_LOCK(&tcp_hostcache.hashbase[i].hch_mtx); TAILQ_FOREACH_SAFE(hc_entry, &tcp_hostcache.hashbase[i].hch_bucket, rmx_q, hc_next) { if (all || hc_entry->rmx_expire <= 0) { TAILQ_REMOVE(&tcp_hostcache.hashbase[i].hch_bucket, hc_entry, rmx_q); uma_zfree(tcp_hostcache.zone, hc_entry); tcp_hostcache.hashbase[i].hch_length--; tcp_hostcache.cache_count--; } else hc_entry->rmx_expire -= tcp_hostcache.prune; } THC_UNLOCK(&tcp_hostcache.hashbase[i].hch_mtx); } callout_reset(&tcp_hc_callout, tcp_hostcache.prune * hz, tcp_hc_purge, 0); }