--- /dev/null
+/*
+ * IRC - Internet Relay Chat, ircd/IPcheck.c
+ * Copyright (C) 1998 Carlo Wood ( Run @ undernet.org )
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+/** @file
+ * @brief Code to count users connected from particular IP addresses.
+ * @version $Id$
+ */
+#include "config.h"
+
+#include "IPcheck.h"
+#include "client.h"
+#include "ircd.h"
+#include "match.h"
+#include "msg.h"
+#include "ircd_alloc.h"
+#include "ircd_events.h"
+#include "ircd_features.h"
+#include "ircd_log.h"
+#include "ircd_string.h" /* ircd_ntoa */
+#include "s_debug.h" /* Debug */
+#include "s_user.h" /* TARGET_DELAY */
+#include "send.h"
+
+/* #include <assert.h> -- Now using assert in ircd_log.h */
+#include <string.h>
+
+/** Stores free target information for a particular user. */
+struct IPTargetEntry {
+ unsigned int count; /**< Number of free targets targets. */
+ unsigned char targets[MAXTARGETS]; /**< Array of recent targets. */
+};
+
+/** Stores recent information about a particular IP address. */
+struct IPRegistryEntry {
+ struct IPRegistryEntry* next; /**< Next entry in the hash chain. */
+ struct IPTargetEntry* target; /**< Recent targets, if any. */
+ struct irc_in_addr addr; /**< IP address for this user. */
+ int last_connect; /**< Last connection attempt timestamp. */
+ unsigned short connected; /**< Number of currently connected clients. */
+ unsigned char attempts; /**< Number of recent connection attempts. */
+};
+
+/** Size of hash table (must be a power of two). */
+#define IP_REGISTRY_TABLE_SIZE 0x10000
+/** Report current time for tracking in IPRegistryEntry::last_connect. */
+#define NOW ((unsigned short)(CurrentTime & 0xffff))
+/** Time from \a x until now, in seconds. */
+#define CONNECTED_SINCE(x) (NOW - (x))
+
+/** Macro for easy access to configured IPcheck clone limit. */
+#define IPCHECK_CLONE_LIMIT feature_int(FEAT_IPCHECK_CLONE_LIMIT)
+/** Macro for easy access to configured IPcheck clone period. */
+#define IPCHECK_CLONE_PERIOD feature_int(FEAT_IPCHECK_CLONE_PERIOD)
+/** Macro for easy access to configured IPcheck clone delay. */
+#define IPCHECK_CLONE_DELAY feature_int(FEAT_IPCHECK_CLONE_DELAY)
+
+/** Hash table for storing IPRegistryEntry entries. */
+static struct IPRegistryEntry* hashTable[IP_REGISTRY_TABLE_SIZE];
+/** List of allocated but unused IPRegistryEntry structs. */
+static struct IPRegistryEntry* freeList;
+/** Periodic timer to look for too-old registry entries. */
+static struct Timer expireTimer;
+
+/** Convert IP addresses to canonical form for comparison. IPv4
+ * addresses are translated into 6to4 form; IPv6 addresses are left
+ * alone.
+ * @param[out] out Receives canonical format for address.
+ * @param[in] in IP address to canonicalize.
+ */
+static void ip_registry_canonicalize(struct irc_in_addr *out, const struct irc_in_addr *in)
+{
+ if (irc_in_addr_is_ipv4(in)) {
+ out->in6_16[0] = htons(0x2002);
+ out->in6_16[1] = in->in6_16[6];
+ out->in6_16[2] = in->in6_16[7];
+ out->in6_16[3] = out->in6_16[4] = out->in6_16[5] = 0;
+ out->in6_16[6] = out->in6_16[7] = 0;
+ } else
+ memcpy(out, in, sizeof(*out));
+}
+
+/** Calculate hash value for an IP address.
+ * @param[in] ip Address to hash; must be in canonical form.
+ * @return Hash value for address.
+ */
+static unsigned int ip_registry_hash(const struct irc_in_addr *ip)
+{
+ unsigned int res;
+ /* Only use the first 64 bits of address, since the last 64 bits
+ * tend to be under user control. */
+ res = ip->in6_16[0] ^ ip->in6_16[1] ^ ip->in6_16[2] ^ ip->in6_16[3];
+ return res & (IP_REGISTRY_TABLE_SIZE - 1);
+}
+
+/** Find an IP registry entry if one exists for the IP address.
+ * If \a ip looks like an IPv6 address, only consider the first 64 bits
+ * of the address. Otherwise, only consider the final 32 bits.
+ * @param[in] ip IP address to search for.
+ * @return Matching registry entry, or NULL if none exists.
+ */
+static struct IPRegistryEntry* ip_registry_find(const struct irc_in_addr *ip)
+{
+ struct irc_in_addr canon;
+ struct IPRegistryEntry* entry;
+ ip_registry_canonicalize(&canon, ip);
+ entry = hashTable[ip_registry_hash(&canon)];
+ for ( ; entry; entry = entry->next) {
+ int bits = (canon.in6_16[0] == htons(0x2002)) ? 48 : 64;
+ if (ipmask_check(&canon, &entry->addr, bits))
+ break;
+ }
+ return entry;
+}
+
+/** Add an IP registry entry to the hash table.
+ * @param[in] entry Registry entry to add.
+ */
+static void ip_registry_add(struct IPRegistryEntry* entry)
+{
+ unsigned int bucket = ip_registry_hash(&entry->addr);
+ entry->next = hashTable[bucket];
+ hashTable[bucket] = entry;
+}
+
+/** Remove an IP registry entry from the hash table.
+ * @param[in] entry Registry entry to add.
+ */
+static void ip_registry_remove(struct IPRegistryEntry* entry)
+{
+ unsigned int bucket = ip_registry_hash(&entry->addr);
+ if (hashTable[bucket] == entry)
+ hashTable[bucket] = entry->next;
+ else {
+ struct IPRegistryEntry* prev = hashTable[bucket];
+ for ( ; prev; prev = prev->next) {
+ if (prev->next == entry) {
+ prev->next = entry->next;
+ break;
+ }
+ }
+ }
+}
+
+/** Allocate a new IP registry entry.
+ * For members that have a sensible default value, that is used.
+ * @return Newly allocated registry entry.
+ */
+static struct IPRegistryEntry* ip_registry_new_entry(void)
+{
+ struct IPRegistryEntry* entry = freeList;
+ if (entry)
+ freeList = entry->next;
+ else
+ entry = (struct IPRegistryEntry*) MyMalloc(sizeof(struct IPRegistryEntry));
+
+ assert(0 != entry);
+ memset(entry, 0, sizeof(struct IPRegistryEntry));
+ entry->last_connect = NOW; /* Seconds since last connect attempt */
+ entry->connected = 1; /* connected clients for this IP */
+ entry->attempts = 1; /* Number attempts for this IP */
+ return entry;
+}
+
+/** Deallocate memory for \a entry.
+ * The entry itself is prepended to #freeList.
+ * @param[in] entry IP registry entry to release.
+ */
+static void ip_registry_delete_entry(struct IPRegistryEntry* entry)
+{
+ if (entry->target)
+ MyFree(entry->target);
+ entry->next = freeList;
+ freeList = entry;
+}
+
+/** Update free target count for \a entry.
+ * @param[in,out] entry IP registry entry to update.
+ */
+static unsigned int ip_registry_update_free_targets(struct IPRegistryEntry* entry)
+{
+ unsigned int free_targets = STARTTARGETS;
+
+ if (entry->target) {
+ free_targets = entry->target->count + (CONNECTED_SINCE(entry->last_connect) / TARGET_DELAY);
+ if (free_targets > STARTTARGETS)
+ free_targets = STARTTARGETS;
+ entry->target->count = free_targets;
+ }
+ return free_targets;
+}
+
+/** Check whether all or part of \a entry needs to be expired.
+ * If the entry is at least 600 seconds stale, free the entire thing.
+ * If it is at least 120 seconds stale, expire its free targets list.
+ * @param[in] entry Registry entry to check for expiration.
+ */
+static void ip_registry_expire_entry(struct IPRegistryEntry* entry)
+{
+ /*
+ * Don't touch this number, it has statistical significance
+ * XXX - blah blah blah
+ */
+ if (CONNECTED_SINCE(entry->last_connect) > 600) {
+ /*
+ * expired
+ */
+ Debug((DEBUG_DNS, "IPcheck expiring registry for %s (no clients connected).", ircd_ntoa(&entry->addr)));
+ ip_registry_remove(entry);
+ ip_registry_delete_entry(entry);
+ }
+ else if (CONNECTED_SINCE(entry->last_connect) > 120 && 0 != entry->target) {
+ /*
+ * Expire storage of targets
+ */
+ MyFree(entry->target);
+ entry->target = 0;
+ }
+}
+
+/** Periodic timer callback to check for expired registry entries.
+ * @param[in] ev Timer event (ignored).
+ */
+static void ip_registry_expire(struct Event* ev)
+{
+ int i;
+ struct IPRegistryEntry* entry;
+ struct IPRegistryEntry* entry_next;
+
+ assert(ET_EXPIRE == ev_type(ev));
+ assert(0 != ev_timer(ev));
+
+ for (i = 0; i < IP_REGISTRY_TABLE_SIZE; ++i) {
+ for (entry = hashTable[i]; entry; entry = entry_next) {
+ entry_next = entry->next;
+ if (0 == entry->connected)
+ ip_registry_expire_entry(entry);
+ }
+ }
+}
+
+/** Initialize the IPcheck subsystem. */
+void IPcheck_init(void)
+{
+ timer_add(timer_init(&expireTimer), ip_registry_expire, 0, TT_PERIODIC, 60);
+}
+
+/** Check whether a new connection from a local client should be allowed.
+ * A connection is rejected if someone from the "same" address (see
+ * ip_registry_find()) connects IPCHECK_CLONE_LIMIT times, each time
+ * separated by no more than IPCHECK_CLONE_PERIOD seconds.
+ * @param[in] addr Address of client.
+ * @param[out] next_target_out Receives time to grant another free target.
+ * @return Non-zero if the connection is permitted, zero if denied.
+ */
+int ip_registry_check_local(const struct irc_in_addr *addr, time_t* next_target_out)
+{
+ struct IPRegistryEntry* entry = ip_registry_find(addr);
+ unsigned int free_targets = STARTTARGETS;
+
+ if (0 == entry) {
+ entry = ip_registry_new_entry();
+ ip_registry_canonicalize(&entry->addr, addr);
+ ip_registry_add(entry);
+ Debug((DEBUG_DNS, "IPcheck added new registry for local connection from %s.", ircd_ntoa(&entry->addr)));
+ return 1;
+ }
+ /* Note that this also counts server connects.
+ * It is hard and not interesting, to change that.
+ * Refuse connection if it would overflow the counter.
+ */
+ if (0 == ++entry->connected)
+ {
+ entry->connected--;
+ Debug((DEBUG_DNS, "IPcheck refusing local connection from %s: counter overflow.", ircd_ntoa(&entry->addr)));
+ return 0;
+ }
+
+ if (CONNECTED_SINCE(entry->last_connect) > IPCHECK_CLONE_PERIOD)
+ entry->attempts = 0;
+
+ free_targets = ip_registry_update_free_targets(entry);
+ entry->last_connect = NOW;
+
+ if (0 == ++entry->attempts) /* Check for overflow */
+ --entry->attempts;
+
+ if (entry->attempts < IPCHECK_CLONE_LIMIT) {
+ if (next_target_out)
+ *next_target_out = CurrentTime - (TARGET_DELAY * free_targets - 1);
+ }
+ else if ((CurrentTime - cli_since(&me)) > IPCHECK_CLONE_DELAY) {
+ /*
+ * Don't refuse connection when we just rebooted the server
+ */
+#ifndef NOTHROTTLE
+ assert(entry->connected > 0);
+ --entry->connected;
+ Debug((DEBUG_DNS, "IPcheck refusing local connection from %s: too fast.", ircd_ntoa(&entry->addr)));
+ return 0;
+#endif
+ }
+ Debug((DEBUG_DNS, "IPcheck accepting local connection from %s.", ircd_ntoa(&entry->addr)));
+ return 1;
+}
+
+/** Check whether a connection from a remote client should be allowed.
+ * This is much more relaxed than ip_registry_check_local(): The only
+ * cause for rejection is when the IPRegistryEntry::connected counter
+ * would overflow.
+ * @param[in] cptr Client that has connected.
+ * @param[in] is_burst Non-zero if client was introduced during a burst.
+ * @return Non-zero if the client should be accepted, zero if they must be killed.
+ */
+int ip_registry_check_remote(struct Client* cptr, int is_burst)
+{
+ struct IPRegistryEntry* entry;
+
+ /*
+ * Mark that we did add/update an IPregistry entry
+ */
+ SetIPChecked(cptr);
+ if (!irc_in_addr_valid(&cli_ip(cptr))) {
+ Debug((DEBUG_DNS, "IPcheck accepting remote connection from invalid %s.", ircd_ntoa(&cli_ip(cptr))));
+ return 1;
+ }
+ entry = ip_registry_find(&cli_ip(cptr));
+ if (0 == entry) {
+ entry = ip_registry_new_entry();
+ ip_registry_canonicalize(&entry->addr, &cli_ip(cptr));
+ if (is_burst)
+ entry->attempts = 0;
+ ip_registry_add(entry);
+ Debug((DEBUG_DNS, "IPcheck added new registry for remote connection from %s.", ircd_ntoa(&entry->addr)));
+ return 1;
+ }
+ /* Avoid overflowing the connection counter. */
+ if (0 == ++entry->connected) {
+ Debug((DEBUG_DNS, "IPcheck refusing remote connection from %s: counter overflow.", ircd_ntoa(&entry->addr)));
+ return 0;
+ }
+ if (CONNECTED_SINCE(entry->last_connect) > IPCHECK_CLONE_PERIOD)
+ entry->attempts = 0;
+ if (!is_burst) {
+ if (0 == ++entry->attempts) {
+ /*
+ * Check for overflow
+ */
+ --entry->attempts;
+ }
+ ip_registry_update_free_targets(entry);
+ entry->last_connect = NOW;
+ }
+ Debug((DEBUG_DNS, "IPcheck counting remote connection from %s.", ircd_ntoa(&entry->addr)));
+ return 1;
+}
+
+/** Handle a client being rejected during connection through no fault
+ * of their own. This "undoes" the effect of ip_registry_check_local()
+ * so the client's address is not penalized for the failure.
+ * @param[in] addr Address of rejected client.
+ * @param[in] disconnect If true, also count the client as disconnecting.
+ */
+void ip_registry_connect_fail(const struct irc_in_addr *addr, int disconnect)
+{
+ struct IPRegistryEntry* entry = ip_registry_find(addr);
+ if (entry) {
+ if (0 == --entry->attempts) {
+ Debug((DEBUG_DNS, "IPcheck noting local connection failure for %s.", ircd_ntoa(&entry->addr)));
+ ++entry->attempts;
+ }
+ if (disconnect) {
+ assert(entry->connected > 0);
+ entry->connected--;
+ }
+ }
+}
+
+/** Handle a client that has successfully connected.
+ * This copies free target information to \a cptr from his address's
+ * registry entry and sends him a NOTICE describing the parameters for
+ * the entry.
+ * @param[in,out] cptr Client that has successfully connected.
+ */
+void ip_registry_connect_succeeded(struct Client *cptr)
+{
+ const char* tr = "";
+ unsigned int free_targets = STARTTARGETS;
+ struct IPRegistryEntry* entry = ip_registry_find(&cli_ip(cptr));
+
+ assert(entry);
+ if (entry->target) {
+ memcpy(cli_targets(cptr), entry->target->targets, MAXTARGETS);
+ free_targets = entry->target->count;
+ tr = " tr";
+ }
+ Debug((DEBUG_DNS, "IPcheck noting local connection success for %s.", ircd_ntoa(&entry->addr)));
+ sendcmdto_one(&me, CMD_NOTICE, cptr, "%C :on %u ca %u(%u) ft %u(%u)%s",
+ cptr, entry->connected, entry->attempts, IPCHECK_CLONE_LIMIT,
+ free_targets, STARTTARGETS, tr);
+}
+
+/** Handle a client that decided to disconnect (or was killed after
+ * completing his connection). This updates the free target
+ * information for his IP registry entry.
+ * @param[in] cptr Client that has exited.
+ */
+void ip_registry_disconnect(struct Client *cptr)
+{
+ struct IPRegistryEntry* entry = ip_registry_find(&cli_ip(cptr));
+ if (!irc_in_addr_valid(&cli_ip(cptr))) {
+ Debug((DEBUG_DNS, "IPcheck noting dicconnect from invalid %s.", ircd_ntoa(&cli_ip(cptr))));
+ return;
+ }
+ assert(entry);
+ assert(entry->connected > 0);
+ Debug((DEBUG_DNS, "IPcheck noting disconnect from %s.", ircd_ntoa(&entry->addr)));
+ /*
+ * If this was the last one, set `last_connect' to disconnect time (used for expiration)
+ */
+ if (0 == --entry->connected) {
+ if (CONNECTED_SINCE(entry->last_connect) > IPCHECK_CLONE_LIMIT * IPCHECK_CLONE_PERIOD) {
+ /*
+ * Otherwise we'd penalize for this old value if the client reconnects within 20 seconds
+ */
+ entry->attempts = 0;
+ }
+ ip_registry_update_free_targets(entry);
+ entry->last_connect = NOW;
+ }
+ if (MyConnect(cptr)) {
+ unsigned int free_targets;
+ /*
+ * Copy the clients targets
+ */
+ if (0 == entry->target) {
+ entry->target = (struct IPTargetEntry*) MyMalloc(sizeof(struct IPTargetEntry));
+ entry->target->count = STARTTARGETS;
+ }
+ assert(0 != entry->target);
+
+ memcpy(entry->target->targets, cli_targets(cptr), MAXTARGETS);
+ /*
+ * This calculation can be pretty unfair towards large multi-user hosts, but
+ * there is "nothing" we can do without also allowing spam bots to send more
+ * messages or by drastically increasing the amount of memory used in the IPregistry.
+ *
+ * The problem is that when a client disconnects, leaving no free targets, then
+ * the next client from that IP number has to pay for it (getting no free targets).
+ * But ALSO the next client, and the next client, and the next client etc - until
+ * another client disconnects that DOES leave free targets. The reason for this
+ * is that if there are 10 SPAM bots, and they all disconnect at once, then they
+ * ALL should get no free targets when reconnecting. We'd need to store an entry
+ * per client (instead of per IP number) to avoid this.
+ */
+ if (cli_nexttarget(cptr) < CurrentTime) {
+ /*
+ * Number of free targets
+ */
+ free_targets = (CurrentTime - cli_nexttarget(cptr)) / TARGET_DELAY + 1;
+ }
+ else
+ free_targets = 0;
+ /*
+ * Add bonus, this is pretty fuzzy, but it will help in some cases.
+ */
+ if ((CurrentTime - cli_firsttime(cptr)) > 600)
+ /*
+ * Was longer then 10 minutes online?
+ */
+ free_targets += (CurrentTime - cli_firsttime(cptr) - 600) / TARGET_DELAY;
+ /*
+ * Finally, store smallest value for Judgment Day
+ */
+ if (free_targets < entry->target->count)
+ entry->target->count = free_targets;
+ }
+}
+
+/** Find number of clients from a particular IP address.
+ * @param[in] addr Address to look up.
+ * @return Number of clients known to be connected from that address.
+ */
+int ip_registry_count(const struct irc_in_addr *addr)
+{
+ struct IPRegistryEntry* entry = ip_registry_find(addr);
+ return (entry) ? entry->connected : 0;
+}
+
+/** Check whether a client is allowed to connect locally.
+ * @param[in] a Address of client.
+ * @param[out] next_target_out Receives time to grant another free target.
+ * @return Non-zero if the connection is permitted, zero if denied.
+ */
+int IPcheck_local_connect(const struct irc_in_addr *a, time_t* next_target_out)
+{
+ assert(0 != next_target_out);
+ return ip_registry_check_local(a, next_target_out);
+}
+
+/** Check whether a client is allowed to connect remotely.
+ * @param[in] cptr Client that has connected.
+ * @param[in] is_burst Non-zero if client was introduced during a burst.
+ * @return Non-zero if the client should be accepted, zero if they must be killed.
+ */
+int IPcheck_remote_connect(struct Client *cptr, int is_burst)
+{
+ assert(0 != cptr);
+ assert(!IsIPChecked(cptr));
+ return ip_registry_check_remote(cptr, is_burst);
+}
+
+/** Handle a client being rejected during connection through no fault
+ * of their own. This "undoes" the effect of ip_registry_check_local()
+ * so the client's address is not penalized for the failure.
+ * @param[in] cptr Client who has been rejected.
+ * @param[in] disconnect If true, also count the client as disconnecting.
+ */
+void IPcheck_connect_fail(const struct Client *cptr, int disconnect)
+{
+ assert(IsIPChecked(cptr));
+ ip_registry_connect_fail(&cli_ip(cptr), disconnect);
+}
+
+/** Handle a client that has successfully connected.
+ * This copies free target information to \a cptr from his address's
+ * registry entry and sends him a NOTICE describing the parameters for
+ * the entry.
+ * @param[in,out] cptr Client that has successfully connected.
+ */
+void IPcheck_connect_succeeded(struct Client *cptr)
+{
+ assert(0 != cptr);
+ assert(IsIPChecked(cptr));
+ ip_registry_connect_succeeded(cptr);
+}
+
+/** Handle a client that decided to disconnect (or was killed after
+ * completing his connection). This updates the free target
+ * information for his IP registry entry.
+ * @param[in] cptr Client that has exited.
+ */
+void IPcheck_disconnect(struct Client *cptr)
+{
+ assert(0 != cptr);
+ assert(IsIPChecked(cptr));
+ ip_registry_disconnect(cptr);
+}
+
+/** Find number of clones of a client.
+ * @param[in] cptr Client whose address to look up.
+ * @return Number of clients known to be connected from that address.
+ */
+unsigned short IPcheck_nr(struct Client *cptr)
+{
+ assert(0 != cptr);
+ return ip_registry_count(&cli_ip(cptr));
+}
projects / ircu2.10.12-pk.git / blobdiff