2 * IRC - Internet Relay Chat, ircd/IPcheck.c
3 * Copyright (C) 1998 Carlo Wood ( Run @ undernet.org )
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2, or (at your option)
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
22 * This file should be edited in a window with a width of 141 characters
29 #include "numnicks.h" /* NumNick, NumServ (GODMODE) */
30 #include "ircd_alloc.h"
31 #include "s_debug.h" /* Debug */
32 #include "s_user.h" /* TARGET_DELAY */
38 struct IPTargetEntry {
40 unsigned char targets[MAXTARGETS];
43 struct IPRegistryEntry {
44 struct IPRegistryEntry* next;
45 struct IPTargetEntry* target;
48 unsigned short connected;
49 unsigned char attempts;
53 * Hash table for IPv4 address registry
55 * Hash table size must be a power of 2
56 * Use 64K hash table to conserve memory
58 #define IP_REGISTRY_TABLE_SIZE 0x10000
59 #define MASK_16 0xffff
61 #define NOW ((unsigned short)(CurrentTime & MASK_16))
62 #define CONNECTED_SINCE(x) (NOW - (x))
64 #define IPCHECK_CLONE_LIMIT 4
65 #define IPCHECK_CLONE_PERIOD 40
66 #define IPCHECK_CLONE_DELAY 600
69 static struct IPRegistryEntry* hashTable[IP_REGISTRY_TABLE_SIZE];
70 static struct IPRegistryEntry* freeList = 0;
72 static unsigned int ip_registry_hash(unsigned int ip)
74 return ((ip >> 16) ^ ip) & (IP_REGISTRY_TABLE_SIZE - 1);
77 static struct IPRegistryEntry* ip_registry_find(unsigned int ip)
79 struct IPRegistryEntry* entry = hashTable[ip_registry_hash(ip)];
80 for ( ; entry; entry = entry->next) {
81 if (entry->addr == ip)
87 static void ip_registry_add(struct IPRegistryEntry* entry)
89 unsigned int bucket = ip_registry_hash(entry->addr);
90 entry->next = hashTable[bucket];
91 hashTable[bucket] = entry;
94 static void ip_registry_remove(struct IPRegistryEntry* entry)
96 unsigned int bucket = ip_registry_hash(entry->addr);
97 if (hashTable[bucket] == entry)
98 hashTable[bucket] = entry->next;
100 struct IPRegistryEntry* prev = hashTable[bucket];
101 for ( ; prev; prev = prev->next) {
102 if (prev->next == entry) {
103 prev->next = entry->next;
110 static struct IPRegistryEntry* ip_registry_new_entry()
112 struct IPRegistryEntry* entry = freeList;
114 freeList = entry->next;
116 entry = (struct IPRegistryEntry*) MyMalloc(sizeof(struct IPRegistryEntry));
119 memset(entry, 0, sizeof(struct IPRegistryEntry));
120 entry->last_connect = NOW; /* Seconds since last connect attempt */
121 entry->connected = 1; /* connected clients for this IP */
122 entry->attempts = 1; /* Number attempts for this IP */
126 static void ip_registry_delete_entry(struct IPRegistryEntry* entry)
129 MyFree(entry->target);
130 entry->next = freeList;
134 static unsigned int ip_registry_update_free_targets(struct IPRegistryEntry* entry)
136 unsigned int free_targets = STARTTARGETS;
139 free_targets = entry->target->count + (CONNECTED_SINCE(entry->last_connect) / TARGET_DELAY);
140 if (free_targets > STARTTARGETS)
141 free_targets = STARTTARGETS;
142 entry->target->count = free_targets;
147 static void ip_registry_expire_entry(struct IPRegistryEntry* entry)
150 * Don't touch this number, it has statistical significance
151 * XXX - blah blah blah
153 if (CONNECTED_SINCE(entry->last_connect) > 600) {
157 ip_registry_remove(entry);
158 ip_registry_delete_entry(entry);
160 else if (CONNECTED_SINCE(entry->last_connect) > 120 && 0 != entry->target) {
162 * Expire storage of targets
164 MyFree(entry->target);
172 static void ip_registry_expire()
175 struct IPRegistryEntry* entry;
176 struct IPRegistryEntry* entry_next;
178 for (i = 0; i < IP_REGISTRY_TABLE_SIZE; ++i) {
179 for (entry = hashTable[i]; entry; entry = entry_next) {
180 entry_next = entry->next;
181 if (0 == entry->connected)
182 ip_registry_expire_entry(entry);
188 * IPcheck_local_connect
191 * A new connection was accept()-ed with IP number `cptr->ip.s_addr'.
194 * Update the IPcheck registry.
196 * 1 : You're allowed to connect.
197 * 0 : You're not allowed to connect.
201 * A connection should be rejected when a connection from the same IP number was
202 * received IPCHECK_CLONE_LIMIT times before this connect attempt, with
203 * reconnect intervals of IPCHECK_CLONE_PERIOD seconds or less.
205 * Free target inheritance:
207 * When the client is accepted, then the number of Free Targets
208 * of the cptr is set to the value stored in the found IPregistry
209 * structure, or left at STARTTARGETS. This can be done by changing
210 * cptr->nexttarget to be `now - (TARGET_DELAY * (FREE_TARGETS - 1))',
211 * where FREE_TARGETS may range from 0 till STARTTARGETS.
213 int ip_registry_check_local(unsigned int addr, time_t* next_target_out)
215 struct IPRegistryEntry* entry = ip_registry_find(addr);
216 unsigned int free_targets = STARTTARGETS;
219 entry = ip_registry_new_entry();
220 entry->addr = addr; /* The IP number of registry entry */
221 ip_registry_add(entry);
224 /* Note that this also connects server connects.
225 * It is hard and not interesting, to change that.
227 * Don't allow more then 255 connects from one IP number, ever
229 if (0 == ++entry->connected)
232 if (CONNECTED_SINCE(entry->last_connect) > IPCHECK_CLONE_PERIOD)
235 free_targets = ip_registry_update_free_targets(entry);
236 entry->last_connect = NOW;
238 if (0 == ++entry->attempts) /* Check for overflow */
241 if (entry->attempts < IPCHECK_CLONE_LIMIT) {
243 *next_target_out = CurrentTime - (TARGET_DELAY * free_targets - 1);
245 else if ((CurrentTime - me.since) > IPCHECK_CLONE_DELAY) {
247 * Don't refuse connection when we just rebooted the server
260 * IPcheck_remote_connect
263 * A remote client connected to Undernet, with IP number `cptr->ip.s_addr'
264 * and hostname `hostname'.
267 * Update the IPcheck registry.
268 * Return 0 on failure, 1 on success.
270 int ip_registry_check_remote(struct Client* cptr, int is_burst)
272 struct IPRegistryEntry* entry = ip_registry_find(cptr->ip.s_addr);
275 * Mark that we did add/update an IPregistry entry
279 entry = ip_registry_new_entry();
280 entry->addr = cptr->ip.s_addr;
283 ip_registry_add(entry);
286 if (0 == ++entry->connected) {
288 * Don't allow more then 255 connects from one IP number, ever
292 if (CONNECTED_SINCE(entry->last_connect) > IPCHECK_CLONE_PERIOD)
295 if (0 == ++entry->attempts) {
301 ip_registry_update_free_targets(entry);
302 entry->last_connect = NOW;
310 * IPcheck_connect_fail
313 * This local client failed to connect due to legal reasons.
316 * Neutralize the effect of calling IPcheck_local_connect, in such
317 * a way that the client won't be penalized when trying to reconnect
320 void ip_registry_connect_fail(unsigned int addr)
322 struct IPRegistryEntry* entry = ip_registry_find(addr);
328 * IPcheck_connect_succeeded
331 * A client succeeded to finish the registration.
333 * Finish IPcheck registration of a successfully, locally connected client.
335 void ip_registry_connect_succeeded(struct Client *cptr)
338 unsigned int free_targets = STARTTARGETS;
339 struct IPRegistryEntry* entry = ip_registry_find(cptr->ip.s_addr);
342 Debug((DEBUG_ERROR, "Missing registry entry for: %s", cptr->sock_ip));
346 memcpy(cptr->targets, entry->target->targets, MAXTARGETS);
347 free_targets = entry->target->count;
350 sendcmdto_one(&me, CMD_NOTICE, cptr, ":on %u ca %u(%u) ft %u(%u)%s",
351 entry->connected, entry->attempts, IPCHECK_CLONE_LIMIT,
352 free_targets, STARTTARGETS, tr);
359 * A local client disconnected or a remote client left Undernet.
362 * Update the IPcheck registry.
363 * Remove all expired IPregistry structures from the hash bucket
364 * that belongs to this clients IP number.
366 void ip_registry_disconnect(struct Client *cptr)
368 struct IPRegistryEntry* entry = ip_registry_find(cptr->ip.s_addr);
371 * trying to find an entry for a server causes this to happen,
372 * servers should never have FLAGS_IPCHECK set
377 * If this was the last one, set `last_connect' to disconnect time (used for expiration)
379 if (0 == --entry->connected) {
380 if (CONNECTED_SINCE(entry->last_connect) > IPCHECK_CLONE_LIMIT * IPCHECK_CLONE_PERIOD) {
382 * Otherwise we'd penetalize for this old value if the client reconnects within 20 seconds
386 ip_registry_update_free_targets(entry);
387 entry->last_connect = NOW;
389 if (MyConnect(cptr)) {
390 unsigned int free_targets;
392 * Copy the clients targets
394 if (0 == entry->target) {
395 entry->target = (struct IPTargetEntry*) MyMalloc(sizeof(struct IPTargetEntry));
396 entry->target->count = STARTTARGETS;
398 assert(0 != entry->target);
400 memcpy(entry->target->targets, cptr->targets, MAXTARGETS);
402 * This calculation can be pretty unfair towards large multi-user hosts, but
403 * there is "nothing" we can do without also allowing spam bots to send more
404 * messages or by drastically increasing the ammount of memory used in the IPregistry.
406 * The problem is that when a client disconnects, leaving no free targets, then
407 * the next client from that IP number has to pay for it (getting no free targets).
408 * But ALSO the next client, and the next client, and the next client etc - until
409 * another client disconnects that DOES leave free targets. The reason for this
410 * is that if there are 10 SPAM bots, and they all disconnect at once, then they
411 * ALL should get no free targets when reconnecting. We'd need to store an entry
412 * per client (instead of per IP number) to avoid this.
414 if (cptr->nexttarget < CurrentTime) {
416 * Number of free targets
418 free_targets = (CurrentTime - cptr->nexttarget) / TARGET_DELAY + 1;
423 * Add bonus, this is pretty fuzzy, but it will help in some cases.
425 if ((CurrentTime - cptr->firsttime) > 600)
427 * Was longer then 10 minutes online?
429 free_targets += (CurrentTime - cptr->firsttime - 600) / TARGET_DELAY;
431 * Finally, store smallest value for Judgement Day
433 if (free_targets < entry->target->count)
434 entry->target->count = free_targets;
441 * Returns number of clients with the same IP number
443 int ip_registry_count(unsigned int addr)
445 struct IPRegistryEntry* entry = ip_registry_find(addr);
446 return (entry) ? entry->connected : 0;
450 * IPcheck_local_connect
453 * A new connection was accept()-ed with IP number `cptr->ip.s_addr'.
456 * Update the IPcheck registry.
458 * 1 : You're allowed to connect.
459 * 0 : You're not allowed to connect.
463 * A connection should be rejected when a connection from the same IP number was
464 * received IPCHECK_CLONE_LIMIT times before this connect attempt, with
465 * reconnect intervals of IPCHECK_CLONE_PERIOD seconds or less.
467 * Free target inheritance:
469 * When the client is accepted, then the number of Free Targets
470 * of the cptr is set to the value stored in the found IPregistry
471 * structure, or left at STARTTARGETS. This can be done by changing
472 * cptr->nexttarget to be `now - (TARGET_DELAY * (FREE_TARGETS - 1))',
473 * where FREE_TARGETS may range from 0 till STARTTARGETS.
475 int IPcheck_local_connect(struct in_addr a, time_t* next_target_out)
477 assert(0 != next_target_out);
478 return ip_registry_check_local(a.s_addr, next_target_out);
482 * IPcheck_remote_connect
485 * A remote client connected to Undernet, with IP number `cptr->ip.s_addr'
486 * and hostname `hostname'.
489 * Update the IPcheck registry.
490 * Return 0 on failure, 1 on success.
492 int IPcheck_remote_connect(struct Client *cptr, int is_burst)
495 return ip_registry_check_remote(cptr, is_burst);
499 * IPcheck_connect_fail
502 * This local client failed to connect due to legal reasons.
505 * Neutralize the effect of calling IPcheck_local_connect, in such
506 * a way that the client won't be penalized when trying to reconnect
509 void IPcheck_connect_fail(struct in_addr a)
511 ip_registry_connect_fail(a.s_addr);
515 * IPcheck_connect_succeeded
518 * A client succeeded to finish the registration.
520 * Finish IPcheck registration of a successfully, locally connected client.
522 void IPcheck_connect_succeeded(struct Client *cptr)
525 ip_registry_connect_succeeded(cptr);
532 * A local client disconnected or a remote client left Undernet.
535 * Update the IPcheck registry.
536 * Remove all expired IPregistry structures from the hash bucket
537 * that belongs to this clients IP number.
539 void IPcheck_disconnect(struct Client *cptr)
542 ip_registry_disconnect(cptr);
548 * Returns number of clients with the same IP number
550 unsigned short IPcheck_nr(struct Client *cptr)
553 return ip_registry_count(cptr->ip.s_addr);
556 void IPcheck_expire()
558 static time_t next_expire = 0;
559 if (next_expire < CurrentTime) {
560 ip_registry_expire();
561 next_expire = CurrentTime + 60;