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.
25 #include "numnicks.h" /* NumNick, NumServ (GODMODE) */
26 #include "ircd_alloc.h"
27 #include "s_bsd.h" /* SetIPChecked */
28 #include "s_debug.h" /* Debug */
29 #include "s_user.h" /* TARGET_DELAY */
33 #include <stdio.h> /* NULL ... bleah */
36 struct IPTargetEntry {
38 unsigned char targets[MAXTARGETS];
41 struct IPRegistryEntry {
42 struct IPRegistryEntry* next;
43 struct IPTargetEntry* target;
45 unsigned short last_connect;
46 unsigned char connected;
47 unsigned char attempts;
51 * Hash table for IPv4 address registry
53 * Hash table size must be a power of 2
54 * Use 64K hash table to conserve memory
56 #define IP_REGISTRY_TABLE_SIZE 0x10000
57 #define MASK_16 0xffff
59 #define NOW ((unsigned short)(CurrentTime & MASK_16))
60 #define CONNECTED_SINCE(x) (NOW - (x))
62 #define IPCHECK_CLONE_LIMIT 2
63 #define IPCHECK_CLONE_PERIOD 20
64 #define IPCHECK_CLONE_DELAY 600
67 static struct IPRegistryEntry* hashTable[IP_REGISTRY_TABLE_SIZE];
68 static struct IPRegistryEntry* freeList = 0;
70 static unsigned int ip_registry_hash(unsigned int ip)
72 return ((ip >> 16) ^ ip) & (IP_REGISTRY_TABLE_SIZE - 1);
75 static struct IPRegistryEntry* ip_registry_find(unsigned int ip)
77 struct IPRegistryEntry* entry = hashTable[ip_registry_hash(ip)];
78 for ( ; entry; entry = entry->next) {
79 if (entry->addr == ip)
85 static void ip_registry_add(struct IPRegistryEntry* entry)
87 unsigned int bucket = ip_registry_hash(entry->addr);
88 entry->next = hashTable[bucket];
89 hashTable[bucket] = entry;
92 static void ip_registry_remove(struct IPRegistryEntry* entry)
94 unsigned int bucket = ip_registry_hash(entry->addr);
95 if (hashTable[bucket] == entry)
96 hashTable[bucket] = entry->next;
98 struct IPRegistryEntry* prev = hashTable[bucket];
99 for ( ; prev; prev = prev->next) {
100 if (prev->next == entry) {
101 prev->next = entry->next;
108 static struct IPRegistryEntry* ip_registry_new_entry()
110 struct IPRegistryEntry* entry = freeList;
112 freeList = entry->next;
114 entry = (struct IPRegistryEntry*) MyMalloc(sizeof(struct IPRegistryEntry));
117 memset(entry, 0, sizeof(struct IPRegistryEntry));
118 entry->last_connect = NOW; /* Seconds since last connect attempt */
119 entry->connected = 1; /* connected clients for this IP */
120 entry->attempts = 1; /* Number attempts for this IP */
124 static void ip_registry_delete_entry(struct IPRegistryEntry* entry)
127 MyFree(entry->target);
128 entry->next = freeList;
132 static unsigned int ip_registry_update_free_targets(struct IPRegistryEntry* entry)
134 unsigned int free_targets = STARTTARGETS;
137 free_targets = entry->target->count + (CONNECTED_SINCE(entry->last_connect) / TARGET_DELAY);
138 if (free_targets > STARTTARGETS)
139 free_targets = STARTTARGETS;
140 entry->target->count = free_targets;
145 static void ip_registry_expire_entry(struct IPRegistryEntry* entry)
148 * Don't touch this number, it has statistical significance
149 * XXX - blah blah blah
151 if (CONNECTED_SINCE(entry->last_connect) > 600) {
155 ip_registry_remove(entry);
156 ip_registry_delete_entry(entry);
158 else if (CONNECTED_SINCE(entry->last_connect) > 120 && 0 != entry->target) {
160 * Expire storage of targets
162 MyFree(entry->target);
170 static void ip_registry_expire()
173 struct IPRegistryEntry* entry;
174 struct IPRegistryEntry* entry_next;
176 for (i = 0; i < IP_REGISTRY_TABLE_SIZE; ++i) {
177 for (entry = hashTable[i]; entry; entry = entry_next) {
178 entry_next = entry->next;
179 if (0 == entry->connected)
180 ip_registry_expire_entry(entry);
186 * IPcheck_local_connect
189 * A new connection was accept()-ed with IP number `cptr->ip.s_addr'.
192 * Update the IPcheck registry.
194 * 1 : You're allowed to connect.
195 * 0 : You're not allowed to connect.
199 * A connection should be rejected when a connection from the same IP number was
200 * received IPCHECK_CLONE_LIMIT times before this connect attempt, with
201 * reconnect intervals of IPCHECK_CLONE_PERIOD seconds or less.
203 * Free target inheritance:
205 * When the client is accepted, then the number of Free Targets
206 * of the cptr is set to the value stored in the found IPregistry
207 * structure, or left at STARTTARGETS. This can be done by changing
208 * cptr->nexttarget to be `now - (TARGET_DELAY * (FREE_TARGETS - 1))',
209 * where FREE_TARGETS may range from 0 till STARTTARGETS.
211 int ip_registry_check_local(unsigned int addr, time_t* next_target_out)
213 struct IPRegistryEntry* entry = ip_registry_find(addr);
214 unsigned int free_targets = STARTTARGETS;
217 entry = ip_registry_new_entry();
218 entry->addr = addr; /* The IP number of registry entry */
219 ip_registry_add(entry);
222 /* Note that this also connects server connects.
223 * It is hard and not interesting, to change that.
225 * Don't allow more then 255 connects from one IP number, ever
227 if (0 == ++entry->connected)
230 if (CONNECTED_SINCE(entry->last_connect) > IPCHECK_CLONE_PERIOD)
233 free_targets = ip_registry_update_free_targets(entry);
234 entry->last_connect = NOW;
236 if (0 == ++entry->attempts) /* Check for overflow */
239 if (entry->attempts < IPCHECK_CLONE_LIMIT) {
241 *next_target_out = CurrentTime - (TARGET_DELAY * free_targets - 1);
243 else if ((CurrentTime - me.since) > IPCHECK_CLONE_DELAY) {
245 * Don't refuse connection when we just rebooted the server
257 * IPcheck_remote_connect
260 * A remote client connected to Undernet, with IP number `cptr->ip.s_addr'
261 * and hostname `hostname'.
264 * Update the IPcheck registry.
265 * Return 0 on failure, 1 on success.
267 int ip_registry_check_remote(struct Client* cptr, int is_burst)
269 struct IPRegistryEntry* entry = ip_registry_find(cptr->ip.s_addr);
272 * Mark that we did add/update an IPregistry entry
276 entry = ip_registry_new_entry();
277 entry->addr = cptr->ip.s_addr;
280 ip_registry_add(entry);
283 if (0 == ++entry->connected) {
285 * Don't allow more then 255 connects from one IP number, ever
289 if (CONNECTED_SINCE(entry->last_connect) > IPCHECK_CLONE_PERIOD)
292 if (0 == ++entry->attempts) {
298 ip_registry_update_free_targets(entry);
299 entry->last_connect = NOW;
306 * IPcheck_connect_fail
309 * This local client failed to connect due to legal reasons.
312 * Neutralize the effect of calling IPcheck_local_connect, in such
313 * a way that the client won't be penalized when trying to reconnect
316 void ip_registry_connect_fail(unsigned int addr)
318 struct IPRegistryEntry* entry = ip_registry_find(addr);
324 * IPcheck_connect_succeeded
327 * A client succeeded to finish the registration.
329 * Finish IPcheck registration of a successfully, locally connected client.
331 void ip_registry_connect_succeeded(struct Client *cptr)
334 unsigned int free_targets = STARTTARGETS;
335 struct IPRegistryEntry* entry = ip_registry_find(cptr->ip.s_addr);
338 Debug((DEBUG_ERROR, "Missing registry entry for: %s", cptr->sock_ip));
342 memcpy(cptr->targets, entry->target->targets, MAXTARGETS);
343 free_targets = entry->target->count;
346 sendto_one(cptr, ":%s NOTICE %s :on %u ca %u(%u) ft %u(%u)%s",
347 me.name, cptr->name, entry->connected, entry->attempts,
348 IPCHECK_CLONE_LIMIT, free_targets, STARTTARGETS, tr);
355 * A local client disconnected or a remote client left Undernet.
358 * Update the IPcheck registry.
359 * Remove all expired IPregistry structures from the hash bucket
360 * that belongs to this clients IP number.
362 void ip_registry_disconnect(struct Client *cptr)
364 struct IPRegistryEntry* entry = ip_registry_find(cptr->ip.s_addr);
367 * trying to find an entry for a server causes this to happen,
368 * servers should never have FLAGS_IPCHECK set
373 * If this was the last one, set `last_connect' to disconnect time (used for expiration)
375 if (0 == --entry->connected) {
376 if (CONNECTED_SINCE(entry->last_connect) > IPCHECK_CLONE_LIMIT * IPCHECK_CLONE_PERIOD) {
378 * Otherwise we'd penetalize for this old value if the client reconnects within 20 seconds
382 ip_registry_update_free_targets(entry);
383 entry->last_connect = NOW;
385 if (MyConnect(cptr)) {
386 unsigned int free_targets;
388 * Copy the clients targets
390 if (0 == entry->target) {
391 entry->target = (struct IPTargetEntry*) MyMalloc(sizeof(struct IPTargetEntry));
392 entry->target->count = STARTTARGETS;
394 assert(0 != entry->target);
396 memcpy(entry->target->targets, cptr->targets, MAXTARGETS);
398 * This calculation can be pretty unfair towards large multi-user hosts, but
399 * there is "nothing" we can do without also allowing spam bots to send more
400 * messages or by drastically increasing the ammount of memory used in the IPregistry.
402 * The problem is that when a client disconnects, leaving no free targets, then
403 * the next client from that IP number has to pay for it (getting no free targets).
404 * But ALSO the next client, and the next client, and the next client etc - until
405 * another client disconnects that DOES leave free targets. The reason for this
406 * is that if there are 10 SPAM bots, and they all disconnect at once, then they
407 * ALL should get no free targets when reconnecting. We'd need to store an entry
408 * per client (instead of per IP number) to avoid this.
410 if (cptr->nexttarget < CurrentTime) {
412 * Number of free targets
414 free_targets = (CurrentTime - cptr->nexttarget) / TARGET_DELAY + 1;
419 * Add bonus, this is pretty fuzzy, but it will help in some cases.
421 if ((CurrentTime - cptr->firsttime) > 600)
423 * Was longer then 10 minutes online?
425 free_targets += (CurrentTime - cptr->firsttime - 600) / TARGET_DELAY;
427 * Finally, store smallest value for Judgement Day
429 if (free_targets < entry->target->count)
430 entry->target->count = free_targets;
437 * Returns number of clients with the same IP number
439 int ip_registry_count(unsigned int addr)
441 struct IPRegistryEntry* entry = ip_registry_find(addr);
442 return (entry) ? entry->connected : 0;
446 * IPcheck_local_connect
449 * A new connection was accept()-ed with IP number `cptr->ip.s_addr'.
452 * Update the IPcheck registry.
454 * 1 : You're allowed to connect.
455 * 0 : You're not allowed to connect.
459 * A connection should be rejected when a connection from the same IP number was
460 * received IPCHECK_CLONE_LIMIT times before this connect attempt, with
461 * reconnect intervals of IPCHECK_CLONE_PERIOD seconds or less.
463 * Free target inheritance:
465 * When the client is accepted, then the number of Free Targets
466 * of the cptr is set to the value stored in the found IPregistry
467 * structure, or left at STARTTARGETS. This can be done by changing
468 * cptr->nexttarget to be `now - (TARGET_DELAY * (FREE_TARGETS - 1))',
469 * where FREE_TARGETS may range from 0 till STARTTARGETS.
471 int IPcheck_local_connect(struct in_addr a, time_t* next_target_out)
473 assert(0 != next_target_out);
474 return ip_registry_check_local(a.s_addr, next_target_out);
478 * IPcheck_remote_connect
481 * A remote client connected to Undernet, with IP number `cptr->ip.s_addr'
482 * and hostname `hostname'.
485 * Update the IPcheck registry.
486 * Return 0 on failure, 1 on success.
488 int IPcheck_remote_connect(struct Client *cptr, int is_burst)
491 return ip_registry_check_remote(cptr, is_burst);
495 * IPcheck_connect_fail
498 * This local client failed to connect due to legal reasons.
501 * Neutralize the effect of calling IPcheck_local_connect, in such
502 * a way that the client won't be penalized when trying to reconnect
505 void IPcheck_connect_fail(struct in_addr a)
507 ip_registry_connect_fail(a.s_addr);
511 * IPcheck_connect_succeeded
514 * A client succeeded to finish the registration.
516 * Finish IPcheck registration of a successfully, locally connected client.
518 void IPcheck_connect_succeeded(struct Client *cptr)
521 ip_registry_connect_succeeded(cptr);
528 * A local client disconnected or a remote client left Undernet.
531 * Update the IPcheck registry.
532 * Remove all expired IPregistry structures from the hash bucket
533 * that belongs to this clients IP number.
535 void IPcheck_disconnect(struct Client *cptr)
538 ip_registry_disconnect(cptr);
544 * Returns number of clients with the same IP number
546 unsigned short IPcheck_nr(struct Client *cptr)
549 return ip_registry_count(cptr->ip.s_addr);
552 void IPcheck_expire()
554 static time_t next_expire = 0;
555 if (next_expire < CurrentTime) {
556 ip_registry_expire();
557 next_expire = CurrentTime + 60;