]>
jfr.im git - irc/quakenet/snircd.git/blob - ircd/IPcheck.c
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.
20 * @brief Code to count users connected from particular IP addresses.
21 * @version $Id: IPcheck.c,v 1.40 2005/08/15 23:22:50 entrope Exp $
30 #include "ircd_alloc.h"
31 #include "ircd_events.h"
32 #include "ircd_features.h"
34 #include "ircd_string.h" /* ircd_ntoa */
35 #include "s_debug.h" /* Debug */
36 #include "s_user.h" /* TARGET_DELAY */
39 /* #include <assert.h> -- Now using assert in ircd_log.h */
42 /** Stores free target information for a particular user. */
43 struct IPTargetEntry
{
44 unsigned int count
; /**< Number of free targets targets. */
45 unsigned char targets
[MAXTARGETS
]; /**< Array of recent targets. */
48 /** Stores recent information about a particular IP address. */
49 struct IPRegistryEntry
{
50 struct IPRegistryEntry
* next
; /**< Next entry in the hash chain. */
51 struct IPTargetEntry
* target
; /**< Recent targets, if any. */
52 struct irc_in_addr addr
; /**< IP address for this user. */
53 int last_connect
; /**< Last connection attempt timestamp. */
54 unsigned short connected
; /**< Number of currently connected clients. */
55 unsigned char attempts
; /**< Number of recent connection attempts. */
58 /** Size of hash table (must be a power of two). */
59 #define IP_REGISTRY_TABLE_SIZE 0x10000
60 /** Report current time for tracking in IPRegistryEntry::last_connect. */
61 #define NOW ((unsigned short)(CurrentTime & 0xffff))
62 /** Time from \a x until now, in seconds. */
63 #define CONNECTED_SINCE(x) (NOW - (x))
65 /** Macro for easy access to configured IPcheck clone limit. */
66 #define IPCHECK_CLONE_LIMIT feature_int(FEAT_IPCHECK_CLONE_LIMIT)
67 /** Macro for easy access to configured IPcheck clone period. */
68 #define IPCHECK_CLONE_PERIOD feature_int(FEAT_IPCHECK_CLONE_PERIOD)
69 /** Macro for easy access to configured IPcheck clone delay. */
70 #define IPCHECK_CLONE_DELAY feature_int(FEAT_IPCHECK_CLONE_DELAY)
72 /** Hash table for storing IPRegistryEntry entries. */
73 static struct IPRegistryEntry
* hashTable
[IP_REGISTRY_TABLE_SIZE
];
74 /** List of allocated but unused IPRegistryEntry structs. */
75 static struct IPRegistryEntry
* freeList
;
76 /** Periodic timer to look for too-old registry entries. */
77 static struct Timer expireTimer
;
79 /** Convert IP addresses to canonical form for comparison. IPv4
80 * addresses are translated into 6to4 form; IPv6 addresses are left
82 * @param[out] out Receives canonical format for address.
83 * @param[in] in IP address to canonicalize.
85 static void ip_registry_canonicalize(struct irc_in_addr
*out
, const struct irc_in_addr
*in
)
87 if (irc_in_addr_is_ipv4(in
)) {
88 out
->in6_16
[0] = htons(0x2002);
89 out
->in6_16
[1] = in
->in6_16
[6];
90 out
->in6_16
[2] = in
->in6_16
[7];
91 out
->in6_16
[3] = out
->in6_16
[4] = out
->in6_16
[5] = 0;
92 out
->in6_16
[6] = out
->in6_16
[7] = 0;
94 memcpy(out
, in
, sizeof(*out
));
97 /** Calculate hash value for an IP address.
98 * @param[in] ip Address to hash; must be in canonical form.
99 * @return Hash value for address.
101 static unsigned int ip_registry_hash(const struct irc_in_addr
*ip
)
104 /* Only use the first 64 bits of address, since the last 64 bits
105 * tend to be under user control. */
106 res
= ip
->in6_16
[0] ^ ip
->in6_16
[1] ^ ip
->in6_16
[2] ^ ip
->in6_16
[3];
107 return res
& (IP_REGISTRY_TABLE_SIZE
- 1);
110 /** Find an IP registry entry if one exists for the IP address.
111 * If \a ip looks like an IPv6 address, only consider the first 64 bits
112 * of the address. Otherwise, only consider the final 32 bits.
113 * @param[in] ip IP address to search for.
114 * @return Matching registry entry, or NULL if none exists.
116 static struct IPRegistryEntry
* ip_registry_find(const struct irc_in_addr
*ip
)
118 struct irc_in_addr canon
;
119 struct IPRegistryEntry
* entry
;
120 ip_registry_canonicalize(&canon
, ip
);
121 entry
= hashTable
[ip_registry_hash(&canon
)];
122 for ( ; entry
; entry
= entry
->next
) {
123 int bits
= (canon
.in6_16
[0] == htons(0x2002)) ? 48 : 64;
124 if (ipmask_check(&canon
, &entry
->addr
, bits
))
130 /** Add an IP registry entry to the hash table.
131 * @param[in] entry Registry entry to add.
133 static void ip_registry_add(struct IPRegistryEntry
* entry
)
135 unsigned int bucket
= ip_registry_hash(&entry
->addr
);
136 entry
->next
= hashTable
[bucket
];
137 hashTable
[bucket
] = entry
;
140 /** Remove an IP registry entry from the hash table.
141 * @param[in] entry Registry entry to add.
143 static void ip_registry_remove(struct IPRegistryEntry
* entry
)
145 unsigned int bucket
= ip_registry_hash(&entry
->addr
);
146 if (hashTable
[bucket
] == entry
)
147 hashTable
[bucket
] = entry
->next
;
149 struct IPRegistryEntry
* prev
= hashTable
[bucket
];
150 for ( ; prev
; prev
= prev
->next
) {
151 if (prev
->next
== entry
) {
152 prev
->next
= entry
->next
;
159 /** Allocate a new IP registry entry.
160 * For members that have a sensible default value, that is used.
161 * @return Newly allocated registry entry.
163 static struct IPRegistryEntry
* ip_registry_new_entry(void)
165 struct IPRegistryEntry
* entry
= freeList
;
167 freeList
= entry
->next
;
169 entry
= (struct IPRegistryEntry
*) MyMalloc(sizeof(struct IPRegistryEntry
));
172 memset(entry
, 0, sizeof(struct IPRegistryEntry
));
173 entry
->last_connect
= NOW
; /* Seconds since last connect attempt */
174 entry
->connected
= 1; /* connected clients for this IP */
175 entry
->attempts
= 1; /* Number attempts for this IP */
179 /** Deallocate memory for \a entry.
180 * The entry itself is prepended to #freeList.
181 * @param[in] entry IP registry entry to release.
183 static void ip_registry_delete_entry(struct IPRegistryEntry
* entry
)
186 MyFree(entry
->target
);
187 entry
->next
= freeList
;
191 /** Update free target count for \a entry.
192 * @param[in,out] entry IP registry entry to update.
194 static unsigned int ip_registry_update_free_targets(struct IPRegistryEntry
* entry
)
196 unsigned int free_targets
= STARTTARGETS
;
199 free_targets
= entry
->target
->count
+ (CONNECTED_SINCE(entry
->last_connect
) / TARGET_DELAY
);
200 if (free_targets
> STARTTARGETS
)
201 free_targets
= STARTTARGETS
;
202 entry
->target
->count
= free_targets
;
207 /** Check whether all or part of \a entry needs to be expired.
208 * If the entry is at least 600 seconds stale, free the entire thing.
209 * If it is at least 120 seconds stale, expire its free targets list.
210 * @param[in] entry Registry entry to check for expiration.
212 static void ip_registry_expire_entry(struct IPRegistryEntry
* entry
)
215 * Don't touch this number, it has statistical significance
216 * XXX - blah blah blah
218 if (CONNECTED_SINCE(entry
->last_connect
) > 600) {
222 Debug((DEBUG_DNS
, "IPcheck expiring registry for %s (no clients connected).", ircd_ntoa(&entry
->addr
)));
223 ip_registry_remove(entry
);
224 ip_registry_delete_entry(entry
);
226 else if (CONNECTED_SINCE(entry
->last_connect
) > 120 && 0 != entry
->target
) {
228 * Expire storage of targets
230 MyFree(entry
->target
);
235 /** Periodic timer callback to check for expired registry entries.
236 * @param[in] ev Timer event (ignored).
238 static void ip_registry_expire(struct Event
* ev
)
241 struct IPRegistryEntry
* entry
;
242 struct IPRegistryEntry
* entry_next
;
244 assert(ET_EXPIRE
== ev_type(ev
));
245 assert(0 != ev_timer(ev
));
247 for (i
= 0; i
< IP_REGISTRY_TABLE_SIZE
; ++i
) {
248 for (entry
= hashTable
[i
]; entry
; entry
= entry_next
) {
249 entry_next
= entry
->next
;
250 if (0 == entry
->connected
)
251 ip_registry_expire_entry(entry
);
256 /** Initialize the IPcheck subsystem. */
257 void IPcheck_init(void)
259 timer_add(timer_init(&expireTimer
), ip_registry_expire
, 0, TT_PERIODIC
, 60);
262 /** Check whether a new connection from a local client should be allowed.
263 * A connection is rejected if someone from the "same" address (see
264 * ip_registry_find()) connects IPCHECK_CLONE_LIMIT times, each time
265 * separated by no more than IPCHECK_CLONE_PERIOD seconds.
266 * @param[in] addr Address of client.
267 * @param[out] next_target_out Receives time to grant another free target.
268 * @return Non-zero if the connection is permitted, zero if denied.
270 int ip_registry_check_local(const struct irc_in_addr
*addr
, time_t* next_target_out
)
272 struct IPRegistryEntry
* entry
= ip_registry_find(addr
);
273 unsigned int free_targets
= STARTTARGETS
;
276 entry
= ip_registry_new_entry();
277 ip_registry_canonicalize(&entry
->addr
, addr
);
278 ip_registry_add(entry
);
279 Debug((DEBUG_DNS
, "IPcheck added new registry for local connection from %s.", ircd_ntoa(&entry
->addr
)));
282 /* Note that this also counts server connects.
283 * It is hard and not interesting, to change that.
284 * Refuse connection if it would overflow the counter.
286 if (0 == ++entry
->connected
)
291 if (CONNECTED_SINCE(entry
->last_connect
) > IPCHECK_CLONE_PERIOD
)
294 free_targets
= ip_registry_update_free_targets(entry
);
295 entry
->last_connect
= NOW
;
297 if (0 == ++entry
->attempts
) /* Check for overflow */
300 if (entry
->attempts
< IPCHECK_CLONE_LIMIT
) {
302 *next_target_out
= CurrentTime
- (TARGET_DELAY
* free_targets
- 1);
304 else if ((CurrentTime
- cli_since(&me
)) > IPCHECK_CLONE_DELAY
) {
306 * Don't refuse connection when we just rebooted the server
309 assert(entry
->connected
> 0);
311 Debug((DEBUG_DNS
, "IPcheck refusing local connection from %s: too fast.", ircd_ntoa(&entry
->addr
)));
315 Debug((DEBUG_DNS
, "IPcheck accepting local connection from %s.", ircd_ntoa(&entry
->addr
)));
319 /** Check whether a connection from a remote client should be allowed.
320 * This is much more relaxed than ip_registry_check_local(): The only
321 * cause for rejection is when the IPRegistryEntry::connected counter
323 * @param[in] cptr Client that has connected.
324 * @param[in] is_burst Non-zero if client was introduced during a burst.
325 * @return Non-zero if the client should be accepted, zero if they must be killed.
327 int ip_registry_check_remote(struct Client
* cptr
, int is_burst
)
329 struct IPRegistryEntry
* entry
;
332 * Mark that we did add/update an IPregistry entry
335 if (!irc_in_addr_valid(&cli_ip(cptr
))) {
336 Debug((DEBUG_DNS
, "IPcheck accepting remote connection from invalid %s.", ircd_ntoa(&cli_ip(cptr
))));
339 entry
= ip_registry_find(&cli_ip(cptr
));
341 entry
= ip_registry_new_entry();
342 ip_registry_canonicalize(&entry
->addr
, &cli_ip(cptr
));
345 ip_registry_add(entry
);
346 Debug((DEBUG_DNS
, "IPcheck added new registry for remote connection from %s.", ircd_ntoa(&entry
->addr
)));
349 /* Avoid overflowing the connection counter. */
350 if (0 == ++entry
->connected
) {
351 Debug((DEBUG_DNS
, "IPcheck refusing remote connection from %s: counter overflow.", ircd_ntoa(&entry
->addr
)));
354 if (CONNECTED_SINCE(entry
->last_connect
) > IPCHECK_CLONE_PERIOD
)
357 if (0 == ++entry
->attempts
) {
363 ip_registry_update_free_targets(entry
);
364 entry
->last_connect
= NOW
;
366 Debug((DEBUG_DNS
, "IPcheck counting remote connection from %s.", ircd_ntoa(&entry
->addr
)));
370 /** Handle a client being rejected during connection through no fault
371 * of their own. This "undoes" the effect of ip_registry_check_local()
372 * so the client's address is not penalized for the failure.
373 * @param[in] addr Address of rejected client.
375 void ip_registry_connect_fail(const struct irc_in_addr
*addr
)
377 struct IPRegistryEntry
* entry
= ip_registry_find(addr
);
378 if (entry
&& 0 == --entry
->attempts
) {
379 Debug((DEBUG_DNS
, "IPcheck noting local connection failure for %s.", ircd_ntoa(&entry
->addr
)));
384 /** Handle a client that has successfully connected.
385 * This copies free target information to \a cptr from his address's
386 * registry entry and sends him a NOTICE describing the parameters for
388 * @param[in,out] cptr Client that has successfully connected.
390 void ip_registry_connect_succeeded(struct Client
*cptr
)
393 unsigned int free_targets
= STARTTARGETS
;
394 struct IPRegistryEntry
* entry
= ip_registry_find(&cli_ip(cptr
));
398 memcpy(cli_targets(cptr
), entry
->target
->targets
, MAXTARGETS
);
399 free_targets
= entry
->target
->count
;
402 Debug((DEBUG_DNS
, "IPcheck noting local connection success for %s.", ircd_ntoa(&entry
->addr
)));
403 sendcmdto_one(&me
, CMD_NOTICE
, cptr
, "%C :on %u ca %u(%u) ft %u(%u)%s",
404 cptr
, entry
->connected
, entry
->attempts
, IPCHECK_CLONE_LIMIT
,
405 free_targets
, STARTTARGETS
, tr
);
408 /** Handle a client that decided to disconnect (or was killed after
409 * completing his connection). This updates the free target
410 * information for his IP registry entry.
411 * @param[in] cptr Client that has exited.
413 void ip_registry_disconnect(struct Client
*cptr
)
415 struct IPRegistryEntry
* entry
= ip_registry_find(&cli_ip(cptr
));
416 if (!irc_in_addr_valid(&cli_ip(cptr
))) {
417 Debug((DEBUG_DNS
, "IPcheck noting dicconnect from invalid %s.", ircd_ntoa(&cli_ip(cptr
))));
421 assert(entry
->connected
> 0);
422 Debug((DEBUG_DNS
, "IPcheck noting disconnect from %s.", ircd_ntoa(&entry
->addr
)));
424 * If this was the last one, set `last_connect' to disconnect time (used for expiration)
426 if (0 == --entry
->connected
) {
427 if (CONNECTED_SINCE(entry
->last_connect
) > IPCHECK_CLONE_LIMIT
* IPCHECK_CLONE_PERIOD
) {
429 * Otherwise we'd penalize for this old value if the client reconnects within 20 seconds
433 ip_registry_update_free_targets(entry
);
434 entry
->last_connect
= NOW
;
436 if (MyConnect(cptr
)) {
437 unsigned int free_targets
;
439 * Copy the clients targets
441 if (0 == entry
->target
) {
442 entry
->target
= (struct IPTargetEntry
*) MyMalloc(sizeof(struct IPTargetEntry
));
443 entry
->target
->count
= STARTTARGETS
;
445 assert(0 != entry
->target
);
447 memcpy(entry
->target
->targets
, cli_targets(cptr
), MAXTARGETS
);
449 * This calculation can be pretty unfair towards large multi-user hosts, but
450 * there is "nothing" we can do without also allowing spam bots to send more
451 * messages or by drastically increasing the amount of memory used in the IPregistry.
453 * The problem is that when a client disconnects, leaving no free targets, then
454 * the next client from that IP number has to pay for it (getting no free targets).
455 * But ALSO the next client, and the next client, and the next client etc - until
456 * another client disconnects that DOES leave free targets. The reason for this
457 * is that if there are 10 SPAM bots, and they all disconnect at once, then they
458 * ALL should get no free targets when reconnecting. We'd need to store an entry
459 * per client (instead of per IP number) to avoid this.
461 if (cli_nexttarget(cptr
) < CurrentTime
) {
463 * Number of free targets
465 free_targets
= (CurrentTime
- cli_nexttarget(cptr
)) / TARGET_DELAY
+ 1;
470 * Add bonus, this is pretty fuzzy, but it will help in some cases.
472 if ((CurrentTime
- cli_firsttime(cptr
)) > 600)
474 * Was longer then 10 minutes online?
476 free_targets
+= (CurrentTime
- cli_firsttime(cptr
) - 600) / TARGET_DELAY
;
478 * Finally, store smallest value for Judgment Day
480 if (free_targets
< entry
->target
->count
)
481 entry
->target
->count
= free_targets
;
485 /** Find number of clients from a particular IP address.
486 * @param[in] addr Address to look up.
487 * @return Number of clients known to be connected from that address.
489 int ip_registry_count(const struct irc_in_addr
*addr
)
491 struct IPRegistryEntry
* entry
= ip_registry_find(addr
);
492 return (entry
) ? entry
->connected
: 0;
495 /** Check whether a client is allowed to connect locally.
496 * @param[in] a Address of client.
497 * @param[out] next_target_out Receives time to grant another free target.
498 * @return Non-zero if the connection is permitted, zero if denied.
500 int IPcheck_local_connect(const struct irc_in_addr
*a
, time_t* next_target_out
)
502 assert(0 != next_target_out
);
503 return ip_registry_check_local(a
, next_target_out
);
506 /** Check whether a client is allowed to connect remotely.
507 * @param[in] cptr Client that has connected.
508 * @param[in] is_burst Non-zero if client was introduced during a burst.
509 * @return Non-zero if the client should be accepted, zero if they must be killed.
511 int IPcheck_remote_connect(struct Client
*cptr
, int is_burst
)
514 assert(!IsIPChecked(cptr
));
515 return ip_registry_check_remote(cptr
, is_burst
);
518 /** Handle a client being rejected during connection through no fault
519 * of their own. This "undoes" the effect of ip_registry_check_local()
520 * so the client's address is not penalized for the failure.
521 * @param[in] cptr Client who has been rejected.
523 void IPcheck_connect_fail(const struct Client
*cptr
)
525 assert(IsIPChecked(cptr
));
526 ip_registry_connect_fail(&cli_ip(cptr
));
529 /** Handle a client that has successfully connected.
530 * This copies free target information to \a cptr from his address's
531 * registry entry and sends him a NOTICE describing the parameters for
533 * @param[in,out] cptr Client that has successfully connected.
535 void IPcheck_connect_succeeded(struct Client
*cptr
)
538 assert(IsIPChecked(cptr
));
539 ip_registry_connect_succeeded(cptr
);
542 /** Handle a client that decided to disconnect (or was killed after
543 * completing his connection). This updates the free target
544 * information for his IP registry entry.
545 * @param[in] cptr Client that has exited.
547 void IPcheck_disconnect(struct Client
*cptr
)
550 assert(IsIPChecked(cptr
));
551 ip_registry_disconnect(cptr
);
554 /** Find number of clones of a client.
555 * @param[in] cptr Client whose address to look up.
556 * @return Number of clients known to be connected from that address.
558 unsigned short IPcheck_nr(struct Client
*cptr
)
561 return ip_registry_count(&cli_ip(cptr
));