2 * IRC - Internet Relay Chat, ircd/hash.c
3 * Copyright (C) 1998 Andrea Cocito, completely rewritten version.
4 * Previous version was Copyright (C) 1991 Darren Reed, the concept
5 * of linked lists for each hash bucket and the move-to-head
6 * optimization has been borrowed from there.
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 1, or (at your option)
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
27 #include "ircd_alloc.h"
28 #include "ircd_chattr.h"
30 #include "ircd_reply.h"
31 #include "ircd_string.h"
41 /* #include <assert.h> -- Now using assert in ircd_log.h */
48 * @brief Hash table management.
51 * This file used to use some very complicated hash function. Now it
52 * uses CRC-32, but effectively remaps each input byte according to a
53 * table initialized at startup.
56 /** Hash table for clients. */
57 static struct Client *clientTable[HASHSIZE];
58 /** Hash table for channels. */
59 static struct Channel *channelTable[HASHSIZE];
60 /** CRC-32 update table. */
61 static uint32_t crc32hash[256];
63 /** Initialize the map used by the hash function. */
66 unsigned int ii, jj, rand, poly;
68 /* First calculate a normal CRC-32 table. */
69 for (ii = 0, poly = 0xedb88320; ii < 256; ii++)
72 for (jj = 0; jj < 8; jj++)
73 rand = (rand & 1) ? poly ^ (rand >> 1) : rand >> 1;
77 /* Now reorder the hash table. */
78 for (ii = 0, rand = 0; ii < 256; ii++)
82 poly = ii + rand % (256 - ii);
84 crc32hash[ii] = crc32hash[poly];
90 /** Output type of hash function. */
91 typedef unsigned int HASHREGS;
93 /** Calculate hash value for a string.
94 * @param[in] n String to hash.
95 * @return Hash value for string.
97 static HASHREGS strhash(const char *n)
99 HASHREGS hash = crc32hash[ToLower(*n++) & 255];
101 hash = (hash >> 8) ^ crc32hash[(hash ^ ToLower(*n++)) & 255];
102 return hash % HASHSIZE;
105 /************************** Externally visible functions ********************/
107 /* Optimization note: in these functions I supposed that the CSE optimization
108 * (Common Subexpression Elimination) does its work decently, this means that
109 * I avoided introducing new variables to do the work myself and I did let
110 * the optimizer play with more free registers, actual tests proved this
111 * solution to be faster than doing things like tmp2=tmp->hnext... and then
112 * use tmp2 myself which would have given less freedom to the optimizer.
115 /** Prepend a client to the appropriate hash bucket.
116 * @param[in] cptr Client to add to hash table.
119 int hAddClient(struct Client *cptr)
121 HASHREGS hashv = strhash(cli_name(cptr));
123 cli_hnext(cptr) = clientTable[hashv];
124 clientTable[hashv] = cptr;
129 /** Prepend a channel to the appropriate hash bucket.
130 * @param[in] chptr Channel to add to hash table.
133 int hAddChannel(struct Channel *chptr)
135 HASHREGS hashv = strhash(chptr->chname);
137 chptr->hnext = channelTable[hashv];
138 channelTable[hashv] = chptr;
143 /** Remove a client from its hash bucket.
144 * @param[in] cptr Client to remove from hash table.
145 * @return Zero if the client is found and removed, -1 if not found.
147 int hRemClient(struct Client *cptr)
149 HASHREGS hashv = strhash(cli_name(cptr));
150 struct Client *tmp = clientTable[hashv];
153 clientTable[hashv] = cli_hnext(cptr);
154 cli_hnext(cptr) = cptr;
159 if (cli_hnext(tmp) == cptr) {
160 cli_hnext(tmp) = cli_hnext(cli_hnext(tmp));
161 cli_hnext(cptr) = cptr;
164 tmp = cli_hnext(tmp);
169 /** Rename a client in the hash table.
170 * @param[in] cptr Client whose nickname is changing.
171 * @param[in] newname New nickname for client.
174 int hChangeClient(struct Client *cptr, const char *newname)
176 HASHREGS newhash = strhash(newname);
181 cli_hnext(cptr) = clientTable[newhash];
182 clientTable[newhash] = cptr;
186 /** Remove a channel from its hash bucket.
187 * @param[in] chptr Channel to remove from hash table.
188 * @return Zero if the channel is found and removed, -1 if not found.
190 int hRemChannel(struct Channel *chptr)
192 HASHREGS hashv = strhash(chptr->chname);
193 struct Channel *tmp = channelTable[hashv];
196 channelTable[hashv] = chptr->hnext;
197 chptr->hnext = chptr;
202 if (tmp->hnext == chptr) {
203 tmp->hnext = tmp->hnext->hnext;
204 chptr->hnext = chptr;
213 /** Find a client by name, filtered by status mask.
214 * If a client is found, it is moved to the top of its hash bucket.
215 * @param[in] name Client name to search for.
216 * @param[in] TMask Bitmask of status bits, any of which are needed to match.
217 * @return Matching client, or NULL if none.
219 struct Client* hSeekClient(const char *name, int TMask)
221 HASHREGS hashv = strhash(name);
222 struct Client *cptr = clientTable[hashv];
225 if (0 == (cli_status(cptr) & TMask) || 0 != ircd_strcmp(name, cli_name(cptr))) {
227 while (prev = cptr, cptr = cli_hnext(cptr)) {
228 if ((cli_status(cptr) & TMask) && (0 == ircd_strcmp(name, cli_name(cptr)))) {
229 cli_hnext(prev) = cli_hnext(cptr);
230 cli_hnext(cptr) = clientTable[hashv];
231 clientTable[hashv] = cptr;
240 /** Find a channel by name.
241 * If a channel is found, it is moved to the top of its hash bucket.
242 * @param[in] name Channel name to search for.
243 * @return Matching channel, or NULL if none.
245 struct Channel* hSeekChannel(const char *name)
247 HASHREGS hashv = strhash(name);
248 struct Channel *chptr = channelTable[hashv];
251 if (0 != ircd_strcmp(name, chptr->chname)) {
252 struct Channel* prev;
253 while (prev = chptr, chptr = chptr->hnext) {
254 if (0 == ircd_strcmp(name, chptr->chname)) {
255 prev->hnext = chptr->hnext;
256 chptr->hnext = channelTable[hashv];
257 channelTable[hashv] = chptr;
267 /* I will add some useful(?) statistics here one of these days,
268 but not for DEBUGMODE: just to let the admins play with it,
269 coders are able to SIGCORE the server and look into what goes
272 /** Report hash table statistics to a client.
273 * @param[in] cptr Client that sent us this message.
274 * @param[in] sptr Client that originated the message.
275 * @param[in] parc Number of arguments.
276 * @param[in] parv Argument array.
279 int m_hash(struct Client *cptr, struct Client *sptr, int parc, char *parv[])
288 sendcmdto_one(&me, CMD_NOTICE, sptr, "%C :Hash Table Statistics", sptr);
290 for (i = 0; i < HASHSIZE; ++i) {
291 if ((cl = clientTable[i])) {
294 for ( ; cl; cl = cli_hnext(cl))
302 sendcmdto_one(&me, CMD_NOTICE, sptr, "%C :Client: entries: %d buckets: %d "
303 "max chain: %d", sptr, count, buckets, max_chain);
309 for (i = 0; i < HASHSIZE; ++i) {
310 if ((ch = channelTable[i])) {
313 for ( ; ch; ch = ch->hnext)
321 sendcmdto_one(&me, CMD_NOTICE, sptr, "%C :Channel: entries: %d buckets: %d "
322 "max chain: %d", sptr, count, buckets, max_chain);
326 /* Nick jupe utilities, these are in a static hash table with entry/bucket
327 ratio of one, collision shift up and roll in a circular fashion, the
328 lowest 12 bits of the hash value are used, deletion is not supported,
329 only addition, test for existence and cleanup of the table are.. */
331 /** Number of bits in jupe hash value. */
332 #define JUPEHASHBITS 12 /* 4096 entries, 64 nick jupes allowed */
333 /** Size of jupe hash table. */
334 #define JUPEHASHSIZE (1<<JUPEHASHBITS)
335 /** Bitmask to select into jupe hash table. */
336 #define JUPEHASHMASK (JUPEHASHSIZE-1)
337 /** Maximum number of jupes allowed. */
338 #define JUPEMAX (1<<(JUPEHASHBITS-6))
340 /** Hash table for jupes. */
341 static char jupeTable[JUPEHASHSIZE][NICKLEN + 1]; /* About 40k */
342 /** Count of jupes. */
343 static int jupesCount;
345 /** Check whether a nickname is juped.
346 * @param[in] nick Nickname to check.
347 * @return Non-zero of the nickname is juped, zero if not.
349 int isNickJuped(const char *nick)
354 for (pos = strhash(nick); (pos &= JUPEHASHMASK), jupeTable[pos][0]; pos++) {
355 if (0 == ircd_strcmp(nick, jupeTable[pos]))
359 return 0; /* A bogus pointer is NOT a juped nick, right ? :) */
362 /** Add a comma-separated list of nick jupes.
363 * @param[in] nicks List of nicks to jupe, separated by commas.
364 * @return Zero on success, non-zero on error.
366 int addNickJupes(const char *nicks)
368 static char temp[BUFSIZE + 1];
375 ircd_strncpy(temp, nicks, BUFSIZE);
376 temp[BUFSIZE] = '\0';
378 for (one = ircd_strtok(&p, temp, ","); one; one = ircd_strtok(&p, NULL, ","))
385 if (!jupeTable[pos][0])
387 if (jupesCount == JUPEMAX)
388 return 1; /* Error: Jupe table is full ! */
390 ircd_strncpy(jupeTable[pos], one, NICKLEN);
391 jupeTable[pos][NICKLEN] = '\000'; /* Better safe than sorry :) */
394 if (0 == ircd_strcmp(one, jupeTable[pos]))
403 /** Empty the table of juped nicknames. */
404 void clearNickJupes(void)
408 for (i = 0; i < JUPEHASHSIZE; i++)
409 jupeTable[i][0] = '\000';
412 /** Report all nick jupes to a user.
413 * @param[in] to Client requesting statistics.
414 * @param[in] sd Stats descriptor for request (ignored).
415 * @param[in] param Extra parameter from user (ignored).
418 stats_nickjupes(struct Client* to, const struct StatDesc* sd, char* param)
421 for (i = 0; i < JUPEHASHSIZE; i++)
423 send_reply(to, RPL_STATSJLINE, jupeTable[i]);
426 /** Send more channels to a client in mid-LIST.
427 * @param[in] cptr Client to send the list to.
429 void list_next_channels(struct Client *cptr)
431 struct ListingArgs *args;
432 struct Channel *chptr;
434 /* Walk consecutive buckets until we hit the end. */
435 for (args = cli_listing(cptr); args->bucket < HASHSIZE; args->bucket++)
437 /* Send all the matching channels in the bucket. */
438 for (chptr = channelTable[args->bucket]; chptr; chptr = chptr->hnext)
440 if (chptr->users > args->min_users
441 && chptr->users < args->max_users
442 && chptr->creationtime > args->min_time
443 && chptr->creationtime < args->max_time
444 && (!args->wildcard[0] || (args->flags & LISTARG_NEGATEWILDCARD) ||
445 (!match(args->wildcard, chptr->chname)))
446 && (!(args->flags & LISTARG_NEGATEWILDCARD) ||
447 match(args->wildcard, chptr->chname))
448 && (!(args->flags & LISTARG_TOPICLIMITS)
450 && chptr->topic_time > args->min_topic_time
451 && chptr->topic_time < args->max_topic_time))
452 && ((args->flags & LISTARG_SHOWSECRET)
453 || ShowChannel(cptr, chptr)))
455 if (args->flags & LISTARG_SHOWMODES) {
456 char modebuf[MODEBUFLEN];
457 char parabuf[MODEBUFLEN];
459 modebuf[0] = modebuf[1] = parabuf[0] = '\0';
460 channel_modes(cptr, modebuf, parabuf, sizeof(parabuf), chptr, NULL);
461 send_reply(cptr, RPL_LIST | SND_EXPLICIT, "%s %u %s %s :%s",
462 chptr->chname, chptr->users, modebuf, parabuf, chptr->topic);
464 send_reply(cptr, RPL_LIST, chptr->chname, chptr->users, chptr->topic);
468 /* If, at the end of the bucket, client sendq is more than half
470 if (MsgQLength(&cli_sendQ(cptr)) > cli_max_sendq(cptr) / 2)
474 /* If we did all buckets, clean the client and send RPL_LISTEND. */
475 if (args->bucket >= HASHSIZE)
477 MyFree(cli_listing(cptr));
478 cli_listing(cptr) = NULL;
479 send_reply(cptr, RPL_LISTEND);