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ircu2/ircd/hash.c

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/*
* IRC - Internet Relay Chat, ircd/hash.c
* Copyright (C) 1998 Andrea Cocito, completely rewritten version.
* Previous version was Copyright (C) 1991 Darren Reed, the concept
* of linked lists for each hash bucket and the move-to-head
* optimization has been borrowed from there.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 1, or (at your option)
* any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include "config.h"
#include "hash.h"
#include "client.h"
#include "channel.h"
#include "ircd_alloc.h"
#include "ircd_chattr.h"
#include "ircd_features.h"
#include "ircd_log.h"
#include "ircd_reply.h"
#include "ircd_string.h"
#include "ircd.h"
#include "match.h"
#include "msg.h"
#include "numeric.h"
#include "random.h"
#include "send.h"
#include "struct.h"
#include "sys.h"
#include "watch.h"
/* #include <assert.h> -- Now using assert in ircd_log.h */
#include <limits.h>
#include <stdlib.h>
#include <string.h>
/** @file
* @brief Hash table management.
* @version $Id: hash.c 1841 2007-11-05 03:01:34Z entrope $
*
* This file used to use some very complicated hash function. Now it
* uses CRC-32, but effectively remaps each input byte according to a
* table initialized at startup.
*/
/** Hash table for clients. */
static struct Client *clientTable[HASHSIZE];
/** Hash table for channels. */
static struct Channel *channelTable[HASHSIZE];
/** Hash table for watches. */
static struct Watch *watchTable[HASHSIZE];
/** CRC-32 update table. */
static uint32_t crc32hash[256];
/** Initialize the map used by the hash function. */
void init_hash(void)
{
unsigned int ii, jj, rand, poly;
/* First calculate a normal CRC-32 table. */
for (ii = 0, poly = 0xedb88320; ii < 256; ii++)
{
rand = ii;
for (jj = 0; jj < 8; jj++)
rand = (rand & 1) ? poly ^ (rand >> 1) : rand >> 1;
crc32hash[ii] = rand;
}
/* Now reorder the hash table. */
for (ii = 0, rand = 0; ii < 256; ii++)
{
if (!rand)
rand = ircrandom();
poly = ii + rand % (256 - ii);
jj = crc32hash[ii];
crc32hash[ii] = crc32hash[poly];
crc32hash[poly] = jj;
rand >>= 8;
}
}
/** Output type of hash function. */
typedef unsigned int HASHREGS;
/** Calculate hash value for a string.
* @param[in] n String to hash.
* @return Hash value for string.
*/
static HASHREGS strhash(const char *n)
{
HASHREGS hash = crc32hash[ToLower(*n++) & 255];
while (*n)
hash = (hash >> 8) ^ crc32hash[(hash ^ ToLower(*n++)) & 255];
return hash % HASHSIZE;
}
/************************** Externally visible functions ********************/
/* Optimization note: in these functions I supposed that the CSE optimization
* (Common Subexpression Elimination) does its work decently, this means that
* I avoided introducing new variables to do the work myself and I did let
* the optimizer play with more free registers, actual tests proved this
* solution to be faster than doing things like tmp2=tmp->hnext... and then
* use tmp2 myself which would have given less freedom to the optimizer.
*/
/** Prepend a client to the appropriate hash bucket.
* @param[in] cptr Client to add to hash table.
* @return Zero.
*/
int hAddClient(struct Client *cptr)
{
HASHREGS hashv = strhash(cli_name(cptr));
cli_hnext(cptr) = clientTable[hashv];
clientTable[hashv] = cptr;
return 0;
}
/** Prepend a channel to the appropriate hash bucket.
* @param[in] chptr Channel to add to hash table.
* @return Zero.
*/
int hAddChannel(struct Channel *chptr)
{
HASHREGS hashv = strhash(chptr->chname);
chptr->hnext = channelTable[hashv];
channelTable[hashv] = chptr;
return 0;
}
/** Remove a client from its hash bucket.
* @param[in] cptr Client to remove from hash table.
* @return Zero if the client is found and removed, -1 if not found.
*/
int hRemClient(struct Client *cptr)
{
HASHREGS hashv = strhash(cli_name(cptr));
struct Client *tmp = clientTable[hashv];
if (tmp == cptr) {
clientTable[hashv] = cli_hnext(cptr);
cli_hnext(cptr) = cptr;
return 0;
}
while (tmp) {
if (cli_hnext(tmp) == cptr) {
cli_hnext(tmp) = cli_hnext(cli_hnext(tmp));
cli_hnext(cptr) = cptr;
return 0;
}
tmp = cli_hnext(tmp);
}
return -1;
}
/** Rename a client in the hash table.
* @param[in] cptr Client whose nickname is changing.
* @param[in] newname New nickname for client.
* @return Zero.
*/
int hChangeClient(struct Client *cptr, const char *newname)
{
HASHREGS newhash = strhash(newname);
assert(0 != cptr);
hRemClient(cptr);
cli_hnext(cptr) = clientTable[newhash];
clientTable[newhash] = cptr;
return 0;
}
/** Remove a channel from its hash bucket.
* @param[in] chptr Channel to remove from hash table.
* @return Zero if the channel is found and removed, -1 if not found.
*/
int hRemChannel(struct Channel *chptr)
{
HASHREGS hashv = strhash(chptr->chname);
struct Channel *tmp = channelTable[hashv];
if (tmp == chptr) {
channelTable[hashv] = chptr->hnext;
chptr->hnext = chptr;
return 0;
}
while (tmp) {
if (tmp->hnext == chptr) {
tmp->hnext = tmp->hnext->hnext;
chptr->hnext = chptr;
return 0;
}
tmp = tmp->hnext;
}
return -1;
}
/** Find a client by name, filtered by status mask.
* If a client is found, it is moved to the top of its hash bucket.
* @param[in] name Client name to search for.
* @param[in] TMask Bitmask of status bits, any of which are needed to match.
* @return Matching client, or NULL if none.
*/
struct Client* hSeekClient(const char *name, int TMask)
{
HASHREGS hashv = strhash(name);
struct Client *cptr = clientTable[hashv];
if (cptr) {
if (0 == (cli_status(cptr) & TMask) || 0 != ircd_strcmp(name, cli_name(cptr))) {
struct Client* prev;
while (prev = cptr, cptr = cli_hnext(cptr)) {
if ((cli_status(cptr) & TMask) && (0 == ircd_strcmp(name, cli_name(cptr)))) {
cli_hnext(prev) = cli_hnext(cptr);
cli_hnext(cptr) = clientTable[hashv];
clientTable[hashv] = cptr;
break;
}
}
}
}
return cptr;
}
/** Find a channel by name.
* If a channel is found, it is moved to the top of its hash bucket.
* @param[in] name Channel name to search for.
* @return Matching channel, or NULL if none.
*/
struct Channel* hSeekChannel(const char *name)
{
HASHREGS hashv = strhash(name);
struct Channel *chptr = channelTable[hashv];
if (chptr) {
if (0 != ircd_strcmp(name, chptr->chname)) {
struct Channel* prev;
while (prev = chptr, chptr = chptr->hnext) {
if (0 == ircd_strcmp(name, chptr->chname)) {
prev->hnext = chptr->hnext;
chptr->hnext = channelTable[hashv];
channelTable[hashv] = chptr;
break;
}
}
}
}
return chptr;
}
/* I will add some useful(?) statistics here one of these days,
but not for DEBUGMODE: just to let the admins play with it,
coders are able to SIGCORE the server and look into what goes
on themselves :-) */
/** Report hash table statistics to a client.
* @param[in] cptr Client that sent us this message.
* @param[in] sptr Client that originated the message.
* @param[in] parc Number of arguments.
* @param[in] parv Argument array.
* @return Zero.
*/
int m_hash(struct Client *cptr, struct Client *sptr, int parc, char *parv[])
{
int max_chain = 0;
int buckets = 0;
int count = 0;
struct Client* cl;
struct Channel* ch;
int i;
sendcmdto_one(&me, CMD_NOTICE, sptr, "%C :Hash Table Statistics", sptr);
for (i = 0; i < HASHSIZE; ++i) {
if ((cl = clientTable[i])) {
int len = 0;
++buckets;
for ( ; cl; cl = cli_hnext(cl))
++len;
if (len > max_chain)
max_chain = len;
count += len;
}
}
sendcmdto_one(&me, CMD_NOTICE, sptr, "%C :Client: entries: %d buckets: %d "
"max chain: %d", sptr, count, buckets, max_chain);
buckets = 0;
count = 0;
max_chain = 0;
for (i = 0; i < HASHSIZE; ++i) {
if ((ch = channelTable[i])) {
int len = 0;
++buckets;
for ( ; ch; ch = ch->hnext)
++len;
if (len > max_chain)
max_chain = len;
count += len;
}
}
sendcmdto_one(&me, CMD_NOTICE, sptr, "%C :Channel: entries: %d buckets: %d "
"max chain: %d", sptr, count, buckets, max_chain);
return 0;
}
/* Nick jupe utilities, these are in a static hash table with entry/bucket
ratio of one, collision shift up and roll in a circular fashion, the
lowest 12 bits of the hash value are used, deletion is not supported,
only addition, test for existence and cleanup of the table are.. */
/** Number of bits in jupe hash value. */
#define JUPEHASHBITS 12 /* 4096 entries, 64 nick jupes allowed */
/** Size of jupe hash table. */
#define JUPEHASHSIZE (1<<JUPEHASHBITS)
/** Bitmask to select into jupe hash table. */
#define JUPEHASHMASK (JUPEHASHSIZE-1)
/** Maximum number of jupes allowed. */
#define JUPEMAX (1<<(JUPEHASHBITS-6))
/** Hash table for jupes. */
static char jupeTable[JUPEHASHSIZE][NICKLEN + 1]; /* About 40k */
/** Count of jupes. */
static int jupesCount;
/** Check whether a nickname is juped.
* @param[in] nick Nickname to check.
* @return Non-zero of the nickname is juped, zero if not.
*/
int isNickJuped(const char *nick)
{
int pos;
if (nick && *nick) {
for (pos = strhash(nick); (pos &= JUPEHASHMASK), jupeTable[pos][0]; pos++) {
if (0 == ircd_strcmp(nick, jupeTable[pos]))
return 1;
}
}
return 0; /* A bogus pointer is NOT a juped nick, right ? :) */
}
/** Add a comma-separated list of nick jupes.
* @param[in] nicks List of nicks to jupe, separated by commas.
* @return Zero on success, non-zero on error.
*/
int addNickJupes(const char *nicks)
{
static char temp[BUFSIZE + 1];
char* one;
char* p;
int pos;
if (nicks && *nicks)
{
ircd_strncpy(temp, nicks, BUFSIZE + 1);
p = NULL;
for (one = ircd_strtok(&p, temp, ","); one; one = ircd_strtok(&p, NULL, ","))
{
if (!*one)
continue;
pos = strhash(one);
loop:
pos &= JUPEHASHMASK;
if (!jupeTable[pos][0])
{
if (jupesCount == JUPEMAX)
return 1; /* Error: Jupe table is full ! */
jupesCount++;
ircd_strncpy(jupeTable[pos], one, NICKLEN + 1);
jupeTable[pos][NICKLEN] = '\000'; /* Better safe than sorry :) */
continue;
}
if (0 == ircd_strcmp(one, jupeTable[pos]))
continue;
++pos;
goto loop;
}
}
return 0;
}
/** Empty the table of juped nicknames. */
void clearNickJupes(void)
{
int i;
jupesCount = 0;
for (i = 0; i < JUPEHASHSIZE; i++)
jupeTable[i][0] = '\000';
}
/** Report all nick jupes to a user.
* @param[in] to Client requesting statistics.
* @param[in] sd Stats descriptor for request (ignored).
* @param[in] param Extra parameter from user (ignored).
*/
void
stats_nickjupes(struct Client* to, const struct StatDesc* sd, char* param)
{
int i;
for (i = 0; i < JUPEHASHSIZE; i++)
if (jupeTable[i][0])
send_reply(to, RPL_STATSJLINE, jupeTable[i]);
}
/** Send more channels to a client in mid-LIST.
* @param[in] cptr Client to send the list to.
*/
void list_next_channels(struct Client *cptr)
{
struct ListingArgs *args;
struct Channel *chptr;
/* Walk consecutive buckets until we hit the end. */
for (args = cli_listing(cptr); args->bucket < HASHSIZE; args->bucket++)
{
/* Send all the matching channels in the bucket. */
for (chptr = channelTable[args->bucket]; chptr; chptr = chptr->hnext)
{
if (chptr->users >= args->min_users
&& chptr->users <= args->max_users
&& chptr->creationtime >= args->min_time
&& chptr->creationtime <= args->max_time
&& (!args->wildcard[0] || (args->flags & LISTARG_NEGATEWILDCARD) ||
(!match(args->wildcard, chptr->chname)))
&& (!(args->flags & LISTARG_NEGATEWILDCARD) ||
match(args->wildcard, chptr->chname))
&& (!(args->flags & LISTARG_TOPICLIMITS)
|| (chptr->topic[0]
&& chptr->topic_time >= args->min_topic_time
&& chptr->topic_time <= args->max_topic_time))
&& ((args->flags & LISTARG_SHOWSECRET)
|| (ShowChannel(cptr, chptr) || IsInvited(cptr, chptr) ||
(!EmptyString(feature_str(FEAT_LIST_PRIVATE_CHANNELS))
&& HiddenChannel(chptr)))))
{
if (!ShowChannel(cptr, chptr) && !IsInvited(cptr, chptr) &&
!(args->flags & LISTARG_SHOWSECRET)) {
send_reply(cptr, RPL_LIST, feature_str(FEAT_LIST_PRIVATE_CHANNELS),
chptr->users, "");
} else if (args->flags & LISTARG_SHOWMODES) {
char modebuf[MODEBUFLEN];
char parabuf[MODEBUFLEN];
modebuf[0] = modebuf[1] = parabuf[0] = '\0';
channel_modes(cptr, modebuf, parabuf, sizeof(parabuf), chptr, NULL);
send_reply(cptr, RPL_LIST | SND_EXPLICIT, "%s %u :[%s%s%s] %s",
chptr->chname, chptr->users, modebuf, (parabuf[0] ? " " : ""),
parabuf, chptr->topic);
} else {
send_reply(cptr, RPL_LIST, chptr->chname, chptr->users, chptr->topic);
}
}
}
/* If, at the end of the bucket, client sendq is more than half
* full, stop. */
if (MsgQLength(&cli_sendQ(cptr)) > cli_max_sendq(cptr) / 2)
break;
}
/* If we did all buckets, clean the client and send RPL_LISTEND. */
if (args->bucket >= HASHSIZE)
{
MyFree(cli_listing(cptr));
cli_listing(cptr) = NULL;
send_reply(cptr, RPL_LISTEND);
}
}
/** Prepend a watch's nick to the appropriate hash bucket.
* @param[in] wptr Watch to add to hash table.
* @return Zero.
*/
int hAddWatch(struct Watch *wptr)
{
register HASHREGS hashv = strhash(wt_nick(wptr));
wt_next(wptr) = watchTable[hashv];
watchTable[hashv] = wptr;
return 0;
}
/** Remove a watch from its hash bucket.
* @param[in] wptr Watch to remove from hash table.
* @return Zero if the watch is found and removed, -1 if not found.
*/
int hRemWatch(struct Watch *wptr)
{
HASHREGS hashv = strhash(wt_nick(wptr));
struct Watch *tmp = watchTable[hashv];
if (tmp == wptr) {
watchTable[hashv] = wt_next(wptr);
wt_next(wptr) = wptr;
return 0;
}
while (tmp) {
if (wt_next(tmp) == wptr) {
wt_next(tmp) = wt_next(wt_next(tmp));
wt_next(wptr) = wptr;
return 0;
}
tmp = wt_next(tmp);
}
return -1;
}
/** Find a watch by nick.
* If a watch's nick is found, it is moved to the top of its hash bucket.
* @param[in] nick Watch nick to search for.
* @return Matching watch, or NULL if none.
*/
struct Watch *hSeekWatch(const char *nick)
{
HASHREGS hashv = strhash(nick);
struct Watch *wptr = watchTable[hashv];
if (wptr) {
if (0 != ircd_strcmp(nick, wt_nick(wptr))) {
struct Watch* prev;
while (prev = wptr, wptr = wt_next(wptr)) {
if (0 == ircd_strcmp(nick, wt_nick(wptr))) {
wt_next(prev) = wt_next(wptr);
wt_next(wptr) = watchTable[hashv];
watchTable[hashv] = wptr;
break;
}
}
}
}
return wptr;
}
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