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.
40 #include "ircd_alloc.h"
41 #include "ircd_chattr.h"
42 #include "ircd_features.h"
44 #include "ircd_string.h"
55 /* #include <assert.h> -- Now using assert in ircd_log.h */
60 /** Keeps track of whowas least-recently-used list. */
62 struct Whowas *ww_list; /**< list of whowas structures */
63 struct Whowas *ww_tail; /**< tail of list for getting structures */
64 unsigned int ww_alloc; /**< alloc count */
65 } wwList = { 0, 0, 0 };
67 /** Hash table of Whowas entries by nickname. */
68 struct Whowas* whowashash[WW_MAX];
71 * @brief Manipulation functions for the whowas list.
74 * Since the introduction of numeric nicks (at least for upstream messages,
75 * like MODE +o <nick>, KICK #chan <nick>, KILL <nick> etc), there is no
76 * real important reason for a nick history anymore.
77 * Nevertheless, there are two reason why we might want to keep it:
78 * @li The /WHOWAS command, which is often useful to catch harassing
79 * users or abusers in general.
80 * @li Clients still use the normal nicks in the client-server protocol,
81 * and it might be considered a nice feature that here we still have
84 * Note however that BOTH reasons make it redundant to keep a whowas history
85 * for users that split off.
87 * The rewrite of comstud was many to safe cpu during net.breaks and therefore
88 * a bit redundant imho (Run).
90 * But - it was written anyway. So lets look at the structure of the
93 * We still have a static table of 'struct Whowas' structures in which we add
94 * new nicks (plus info) as in a rotating buffer. We keep a global pointer
95 * `whowas_next' that points to the next entry to be overwritten - or to
96 * the oldest entry in the table (which is the same).
98 * Each entry keeps pointers for two doubly linked lists (thus four pointers):
99 * A list of the entries that have the same hash value ('hashv list'), and
100 * a list of the entries that have the same online pointer (`online list').
101 * Note that the last list (pointers) is only updated as long as online points
102 * to the corresponding client: As soon as the client signs off, this list
103 * is not anymore maintained (and hopefully not used anymore either ;).
105 * So now we have two ways of accessing this database:
106 * @li Given a <nick> we can calculate a hashv and then whowashash[hashv] will
107 * point to the start of the 'hash list': all entries with the same hashv.
108 * We'll have to search this list to find the entry with the correct <nick>.
109 * Once we found the correct whowas entry, we have a pointer to the
110 * corresponding client - if still online - for nick chasing purposes.
111 * Note that the same nick can occur multiple times in the whowas history,
112 * each of these having the same hash value of course. While a /WHOWAS on
113 * just a nick will return all entries, nick chasing will only find the
114 * first in the list. Because new entries are added at the start of the
115 * 'hash list' we will always find the youngest entry, which is what we want.
116 * @li Given an online client we have a pointer to the first whowas entry
117 * of the linked list of whowas entries that all belong to this client.
118 * We ONLY need this to reset all `online' pointers when this client
123 * Note that following:
125 * @li We *only* (need to) change the 'hash list' and the 'online' list
127 * @li There we always ADD an entry to the BEGINNING of the 'hash list'
128 * and the 'online list': *new* entries are at the start of the lists.
129 * The oldest entries are at the end of the lists.
130 * @li We always REMOVE the oldest entry we have (whowas_next), this means
131 * that this is always an entry that is at the *end* of the 'hash list'
132 * and 'online list' that it is a part of: the next pointer will
134 * @li The previous pointer is *only* used to update the next pointer of the
135 * previous entry, therefore we could better use a pointer to this
136 * next pointer: That is faster - saves us a 'if' test (it will never be
137 * NULL because the last added entry will point to the pointer that
138 * points to the start of the list) and we won't need special code to
139 * update the list start pointers.
141 * I incorporated these considerations into the code below.
146 /** Unlink a Whowas structure and free everything inside it.
147 * @param[in,out] ww The whowas record to free.
148 * @return The pointer \a ww.
150 static struct Whowas *
151 whowas_clean(struct Whowas *ww)
156 Debug((DEBUG_LIST, "Cleaning whowas structure for %s", ww->name));
158 if (ww->online) { /* unlink from client */
159 if (ww->cnext) /* shouldn't happen, but I'm not confident of that */
160 ww->cnext->cprevnextp = ww->cprevnextp;
161 *ww->cprevnextp = ww->cnext;
164 if (ww->hnext) /* now unlink from hash table */
165 ww->hnext->hprevnextp = ww->hprevnextp;
166 *ww->hprevnextp = ww->hnext;
168 if (ww->wnext) /* unlink from whowas linked list... */
169 ww->wnext->wprev = ww->wprev;
171 ww->wprev->wnext = ww->wnext;
173 if (wwList.ww_tail == ww) /* update tail pointer appropriately */
174 wwList.ww_tail = ww->wprev;
180 MyFree(ww->username);
182 MyFree(ww->hostname);
184 MyFree(ww->realhost);
186 MyFree(ww->servername);
188 MyFree(ww->realname);
195 /** Clean and free a whowas record.
196 * @param[in] ww Whowas record to free.
199 whowas_free(struct Whowas *ww)
204 Debug((DEBUG_LIST, "Destroying whowas structure for %s", ww->name));
212 /** Return a fresh Whowas record.
213 * If the total number of records is smaller than determined by
214 * FEAT_NICKNAMEHISTORYLENGTH, allocate a new one. Otherwise,
215 * reuse the oldest record in use.
216 * @return A pointer to a clean Whowas.
218 static struct Whowas *
223 if (wwList.ww_alloc >= feature_int(FEAT_NICKNAMEHISTORYLENGTH)) {
224 /* reclaim the oldest whowas entry */
225 ww = whowas_clean(wwList.ww_tail);
227 /* allocate a new one */
229 ww = (struct Whowas *) MyMalloc(sizeof(struct Whowas));
233 memset(ww, 0, sizeof(*ww));
237 /** If necessary, trim the whowas list.
238 * This function trims the whowas list until it contains no more than
239 * FEAT_NICKNAMEHISTORYLENGTH records.
244 Debug((DEBUG_LIST, "whowas_realloc() called with alloc count %d, "
245 "history length %d, tail pointer %p", wwList.ww_alloc,
246 feature_int(FEAT_NICKNAMEHISTORYLENGTH), wwList.ww_tail));
248 while (wwList.ww_alloc > feature_int(FEAT_NICKNAMEHISTORYLENGTH)) {
249 if (!wwList.ww_tail) { /* list is empty... */
250 Debug((DEBUG_LIST, "whowas list emptied with alloc count %d",
255 whowas_free(wwList.ww_tail); /* free oldest element of whowas list */
259 /** Add a client to the whowas list.
260 * @param[in] cptr Client to add.
261 * @param[in] still_on If non-zero, link the record to the client's personal history.
263 void add_history(struct Client *cptr, int still_on)
267 if (!(ww = whowas_alloc()))
268 return; /* couldn't get a structure */
270 ww->hashv = hash_whowas_name(cli_name(cptr)); /* initialize struct */
271 ww->logoff = CurrentTime;
272 DupString(ww->name, cli_name(cptr));
273 DupString(ww->username, cli_user(cptr)->username);
274 DupString(ww->hostname, cli_user(cptr)->host);
275 if (HasHiddenHost(cptr))
276 DupString(ww->realhost, cli_user(cptr)->realhost);
277 DupString(ww->servername, cli_name(cli_user(cptr)->server));
278 DupString(ww->realname, cli_info(cptr));
279 if (cli_user(cptr)->away)
280 DupString(ww->away, cli_user(cptr)->away);
282 if (still_on) { /* user changed nicknames... */
284 if ((ww->cnext = cli_whowas(cptr)))
285 ww->cnext->cprevnextp = &ww->cnext;
286 ww->cprevnextp = &(cli_whowas(cptr));
287 cli_whowas(cptr) = ww;
288 } else /* user quit */
291 /* link new whowas structure to list */
292 ww->wnext = wwList.ww_list;
294 wwList.ww_list->wprev = ww;
297 if (!wwList.ww_tail) /* update the tail pointer... */
300 /* Now link it into the hash table */
301 if ((ww->hnext = whowashash[ww->hashv]))
302 ww->hnext->hprevnextp = &ww->hnext;
303 ww->hprevnextp = &whowashash[ww->hashv];
304 whowashash[ww->hashv] = ww;
307 /** Clear all Whowas::online pointers that point to a client.
308 * @param[in] cptr Client who is going offline.
310 void off_history(const struct Client *cptr)
314 for (temp = cli_whowas(cptr); temp; temp = temp->cnext)
318 /** Find a client who has recently used a particular nickname.
319 * @param[in] nick Nickname to find.
320 * @param[in] timelimit Maximum age for entry.
321 * @return User's online client, or NULL if none is found.
323 struct Client *get_history(const char *nick, time_t timelimit)
325 struct Whowas *temp = whowashash[hash_whowas_name(nick)];
326 timelimit = CurrentTime - timelimit;
328 for (; temp; temp = temp->hnext)
329 if (0 == ircd_strcmp(nick, temp->name) && temp->logoff > timelimit)
335 /** Count memory used by whowas list.
336 * @param[out] wwu Number of entries in whowas list.
337 * @param[out] wwum Total number of bytes used by nickname, username,
338 * hostname and servername fields.
339 * @param[out] wwa Number of away strings in whowas list.
340 * @param[out] wwam Total number of bytes used by away strings.
342 void count_whowas_memory(int *wwu, size_t *wwum, int *wwa, size_t *wwam)
354 for (tmp = wwList.ww_list; tmp; tmp = tmp->wnext) {
356 um += (strlen(tmp->name) + 1);
357 um += (strlen(tmp->username) + 1);
358 um += (strlen(tmp->hostname) + 1);
359 um += (strlen(tmp->servername) + 1);
362 am += (strlen(tmp->away) + 1);
371 /** Initialize whowas table. */
372 void initwhowas(void)
376 for (i = 0; i < WW_MAX; i++)
380 /** Calculate a hash value for a string.
381 * @param[in] name Nickname to calculate hash over.
382 * @return Calculated hash value.
384 unsigned int hash_whowas_name(const char *name)
386 unsigned int hash = 0;
387 unsigned int hash2 = 0;
392 lower = ToLower(*name);
393 hash = (hash << 1) + lower;
394 hash2 = (hash2 >> 1) + lower;
398 return ((hash & WW_MAX_INITIAL_MASK) << BITS_PER_COL) +
399 (hash2 & BITS_PER_COL_MASK);