2 * IRC - Internet Relay Chat, ircd/whowas.c
3 * Copyright (C) 1990 Markku Savela
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 1, 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.
19 * --- avalon --- 6th April 1992
20 * rewritten to scrap linked lists and use a table of structures which
21 * is referenced like a circular loop. Should be faster and more efficient.
23 * --- comstud --- 25th March 1997
24 * Everything rewritten from scratch. Avalon's code was bad. My version
25 * is faster and more efficient. No more hangs on /squits and you can
26 * safely raise NICKNAMEHISTORYLENGTH to a higher value without hurting
29 * --- comstud --- 5th August 1997
30 * Fixed for Undernet..
32 * --- Run --- 27th August 1997
33 * Speeded up the code, added comments.
42 #include "ircd_alloc.h"
43 #include "ircd_chattr.h"
44 #include "ircd_features.h"
45 #include "ircd_string.h"
63 struct Whowas *ww_list; /* list of whowas structures */
64 struct Whowas *ww_tail; /* tail of list for getting structures */
65 unsigned int ww_alloc; /* alloc count */
66 } wwList = { 0, 0, 0 };
68 struct Whowas* whowashash[WW_MAX];
71 * Since the introduction of numeric nicks (at least for upstream messages,
72 * like MODE +o <nick>, KICK #chan <nick>, KILL <nick> etc), there is no
73 * real important reason for a nick history anymore.
74 * Nevertheless, there are two reason why we might want to keep it:
75 * 1) The /WHOWAS command, which is often usefull to catch harrashing
76 * users or abusers in general.
77 * 2) Clients still use the normal nicks in the client-server protocol,
78 * and it might be considered a nice feature that here we still have
80 * Note however that BOTH reasons make it redundant to keep a whowas history
81 * for users that split off.
83 * The rewrite of comstud was many to safe cpu during net.breaks and therefore
84 * a bit redundant imho (Run).
86 * But - it was written anyway. So lets look at the structure of the
89 * We still have a static table of 'struct Whowas' structures in which we add
90 * new nicks (plus info) as in a rotating buffer. We keep a global pointer
91 * `whowas_next' that points to the next entry to be overwritten - or to
92 * the oldest entry in the table (which is the same).
94 * Each entry keeps pointers for two doubly linked lists (thus four pointers):
95 * A list of the entries that have the same hash value ('hashv list'), and
96 * a list of the entries that have the same online pointer (`online list').
97 * Note that the last list (pointers) is only updated as long as online points
98 * to the corresponding client: As soon as the client signs off, this list
99 * is not anymore maintained (and hopefully not used anymore either ;).
101 * So now we have two ways of accessing this database:
102 * 1) Given a <nick> we can calculate a hashv and then whowashash[hashv] will
103 * point to the start of the 'hash list': all entries with the same hashv.
104 * We'll have to search this list to find the entry with the correct <nick>.
105 * Once we found the correct whowas entry, we have a pointer to the
106 * corresponding client - if still online - for nich chasing purposes.
107 * Note that the same nick can occur multiple times in the whowas history,
108 * each of these having the same hash value of course. While a /WHOWAS on
109 * just a nick will return all entries, nick chasing will only find the
110 * first in the list. Because new entries are added at the start of the
111 * 'hash list' we will always find the youngest entry, which is what we want.
112 * 2) Given an online client we have a pointer to the first whowas entry
113 * of the linked list of whowas entries that all belong to this client.
114 * We ONLY need this to reset all `online' pointers when this client
119 * Note that following:
121 * a) We *only* (need to) change the 'hash list' and the 'online' list
123 * b) There we always ADD an entry to the BEGINNING of the 'hash list'
124 * and the 'online list': *new* entries are at the start of the lists.
125 * The oldest entries are at the end of the lists.
126 * c) We always REMOVE the oldest entry we have (whowas_next), this means
127 * that this is always an entry that is at the *end* of the 'hash list'
128 * and 'online list' that it is a part of: the next pointer will
130 * d) The previous pointer is *only* used to update the next pointer of the
131 * previous entry, therefore we could better use a pointer to this
132 * next pointer: That is faster - saves us a 'if' test (it will never be
133 * NULL because the last added entry will point to the pointer that
134 * points to the start of the list) and we won't need special code to
135 * update the list start pointers.
137 * I incorporated these considerations into the code below.
144 * Clean up a whowas structure
146 static struct Whowas *
147 whowas_clean(struct Whowas *ww)
152 Debug((DEBUG_LIST, "Cleaning whowas structure for %s", ww->name));
154 if (ww->online) { /* unlink from client */
155 if (ww->cnext) /* shouldn't happen, but I'm not confident of that */
156 ww->cnext->cprevnextp = ww->cprevnextp;
157 *ww->cprevnextp = ww->cnext;
160 if (ww->hnext) /* now unlink from hash table */
161 ww->hnext->hprevnextp = ww->hprevnextp;
162 *ww->hprevnextp = ww->hnext;
164 if (ww->wnext) /* unlink from whowas linked list... */
165 ww->wnext->wprev = ww->wprev;
167 ww->wprev->wnext = ww->wnext;
169 if (wwList.ww_tail == ww) /* update tail pointer appropriately */
170 wwList.ww_tail = ww->wprev;
176 MyFree(ww->username);
178 MyFree(ww->hostname);
180 MyFree(ww->servername);
182 MyFree(ww->realname);
191 * Free a struct Whowas...
194 whowas_free(struct Whowas *ww)
199 Debug((DEBUG_LIST, "Destroying whowas structure for %s", ww->name));
209 * Initializes a given whowas structure
211 static struct Whowas *
212 whowas_init(struct Whowas *ww)
238 * Returns a whowas structure to use
240 static struct Whowas *
243 if (wwList.ww_alloc >= feature_int(FEAT_NICKNAMEHISTORYLENGTH))
244 return whowas_init(whowas_clean(wwList.ww_tail));
246 wwList.ww_alloc++; /* going to allocate a new one... */
247 return whowas_init((struct Whowas *) MyMalloc(sizeof(struct Whowas)));
257 Debug((DEBUG_LIST, "whowas_realloc() called with alloc count %d, "
258 "history length %d, tail pointer %p", wwList.ww_alloc,
259 feature_int(FEAT_NICKNAMEHISTORYLENGTH), wwList.ww_tail));
261 while (wwList.ww_alloc > feature_int(FEAT_NICKNAMEHISTORYLENGTH)) {
262 if (!wwList.ww_tail) { /* list is empty... */
263 Debug((DEBUG_LIST, "whowas list emptied with alloc count %d",
268 whowas_free(wwList.ww_tail); /* free oldest element of whowas list */
275 * Add a client (cptr) that just changed nick (still_on == true), or
276 * just signed off (still_on == false) to the `whowas' table.
278 * If the entry used was already in use, then this entry is
281 void add_history(struct Client *cptr, int still_on)
285 if (!(ww = whowas_alloc()))
286 return; /* couldn't get a structure */
288 ww->hashv = hash_whowas_name(cli_name(cptr)); /* initialize struct */
289 ww->logoff = CurrentTime;
290 DupString(ww->name, cli_name(cptr));
291 DupString(ww->username, cli_user(cptr)->username);
292 DupString(ww->hostname, cli_user(cptr)->host);
293 DupString(ww->servername, cli_name(cli_user(cptr)->server));
294 DupString(ww->realname, cli_info(cptr));
295 if (cli_user(cptr)->away)
296 DupString(ww->away, cli_user(cptr)->away);
298 if (still_on) { /* user changed nicknames... */
300 if ((ww->cnext = cli_whowas(cptr)))
301 ww->cnext->cprevnextp = &ww->cnext;
302 ww->cprevnextp = &(cli_whowas(cptr));
303 cli_whowas(cptr) = ww;
304 } else /* user quit */
307 /* link new whowas structure to list */
308 ww->wnext = wwList.ww_list;
310 wwList.ww_list->wprev = ww;
313 if (!wwList.ww_tail) /* update the tail pointer... */
316 /* Now link it into the hash table */
317 if ((ww->hnext = whowashash[ww->hashv]))
318 ww->hnext->hprevnextp = &ww->hnext;
319 ww->hprevnextp = &whowashash[ww->hashv];
320 whowashash[ww->hashv] = ww;
326 * Client `cptr' signed off: Set all `online' pointers
327 * corresponding to this client to NULL.
329 void off_history(const struct Client *cptr)
333 for (temp = cli_whowas(cptr); temp; temp = temp->cnext)
340 * Return a pointer to a client that had nick `nick' not more then
341 * `timelimit' seconds ago, if still on line. Otherwise return NULL.
343 * This function is used for "nick chasing"; since the use of numeric
344 * nicks for "upstream" messages in ircu2.10, this is only used for
345 * looking up non-existing nicks in client->server messages.
347 struct Client *get_history(const char *nick, time_t timelimit)
349 struct Whowas *temp = whowashash[hash_whowas_name(nick)];
350 timelimit = CurrentTime - timelimit;
352 for (; temp; temp = temp->hnext)
353 if (0 == ircd_strcmp(nick, temp->name) && temp->logoff > timelimit)
359 void count_whowas_memory(int *wwu, size_t *wwum, int *wwa, size_t *wwam)
371 for (tmp = wwList.ww_list; tmp; tmp = tmp->wnext) {
373 um += (strlen(tmp->name) + 1);
374 um += (strlen(tmp->username) + 1);
375 um += (strlen(tmp->hostname) + 1);
376 um += (strlen(tmp->servername) + 1);
379 am += (strlen(tmp->away) + 1);
389 void initwhowas(void)
393 for (i = 0; i < WW_MAX; i++)
397 unsigned int hash_whowas_name(const char *name)
399 unsigned int hash = 0;
400 unsigned int hash2 = 0;
405 lower = ToLower(*name);
406 hash = (hash << 1) + lower;
407 hash2 = (hash2 >> 1) + lower;
411 return ((hash & WW_MAX_INITIAL_MASK) << BITS_PER_COL) +
412 (hash2 & BITS_PER_COL_MASK);