trunk/src/hash.c

/*
 *  ircd-hybrid: an advanced, lightweight Internet Relay Chat Daemon (ircd)
 *
 *  Copyright (c) 1997-2016 ircd-hybrid development team
 *
 *  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 2 of the License, 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301
 *  USA
 */

/*! \file hash.c
 * \brief Hash table management.
 * \version $Id$
 */

#include "stdinc.h"
#include "list.h"
#include "conf.h"
#include "channel.h"
#include "channel_mode.h"
#include "client.h"
#include "modules.h"
#include "hash.h"
#include "id.h"
#include "resv.h"
#include "rng_mt.h"
#include "userhost.h"
#include "irc_string.h"
#include "ircd.h"
#include "numeric.h"
#include "send.h"
#include "memory.h"
#include "mempool.h"
#include "dbuf.h"
#include "user.h"


static unsigned int hashf_xor_key;

/* The actual hash tables, They MUST be of the same HASHSIZE, variable
 * size tables could be supported but the rehash routine should also
 * rebuild the transformation maps, I kept the tables of equal size
 * so that I can use one hash function.
 */
static struct Client *idTable[HASHSIZE];
static struct Client *clientTable[HASHSIZE];
static struct Channel *channelTable[HASHSIZE];
static struct UserHost *userhostTable[HASHSIZE];


/* hash_init()
 *
 * inputs       - NONE
 * output       - NONE
 * side effects - Initialize the maps used by hash
 *                functions and clear the tables
 */
void
hash_init(void)
{
  do
    hashf_xor_key = genrand_int32() % 256;  /* better than nothing --adx */
  while (!hashf_xor_key);
}

/*
 * New hash function based on the Fowler/Noll/Vo (FNV) algorithm from
 * http://www.isthe.com/chongo/tech/comp/fnv/
 *
 * Here, we use the FNV-1 method, which gives slightly better results
 * than FNV-1a.   -Michael
 */
unsigned int
strhash(const char *name)
{
  const unsigned char *p = (const unsigned char *)name;
  unsigned int hval = FNV1_32_INIT;

  if (EmptyString(p))
    return 0;

  for (; *p; ++p)
  {
    hval += (hval << 1) + (hval <<  4) + (hval << 7) +
            (hval << 8) + (hval << 24);
    hval ^= (ToLower(*p) ^ hashf_xor_key);
  }

  return (hval >> FNV1_32_BITS) ^ (hval & ((1 << FNV1_32_BITS) - 1));
}

/************************** 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.
 */

/* hash_add_client()
 *
 * inputs       - pointer to client
 * output       - NONE
 * side effects - Adds a client's name in the proper hash linked
 *                list, can't fail, client_p must have a non-null
 *                name or expect a coredump, the name is infact
 *                taken from client_p->name
 */
void
hash_add_client(struct Client *client_p)
{
  const unsigned int hashv = strhash(client_p->name);

  client_p->hnext = clientTable[hashv];
  clientTable[hashv] = client_p;
}

/* hash_add_channel()
 *
 * inputs       - pointer to channel
 * output       - NONE
 * side effects - Adds a channel's name in the proper hash linked
 *                list, can't fail. chptr must have a non-null name
 *                or expect a coredump. As before the name is taken
 *                from chptr->name, we do hash its entire lenght
 *                since this proved to be statistically faster
 */
void
hash_add_channel(struct Channel *chptr)
{
  const unsigned int hashv = strhash(chptr->name);

  chptr->hnextch = channelTable[hashv];
  channelTable[hashv] = chptr;
}

void
hash_add_userhost(struct UserHost *userhost)
{
  const unsigned int hashv = strhash(userhost->host);

  userhost->next = userhostTable[hashv];
  userhostTable[hashv] = userhost;
}

void
hash_add_id(struct Client *client_p)
{
  const unsigned int hashv = strhash(client_p->id);

  client_p->idhnext = idTable[hashv];
  idTable[hashv] = client_p;
}

/* hash_del_id()
 *
 * inputs       - pointer to client
 * output       - NONE
 * side effects - Removes an ID from the hash linked list
 */
void
hash_del_id(struct Client *client_p)
{
  const unsigned int hashv = strhash(client_p->id);
  struct Client *tmp = idTable[hashv];

  if (tmp)
  {
    if (tmp == client_p)
    {
      idTable[hashv] = client_p->idhnext;
      client_p->idhnext = client_p;
    }
    else
    {
      while (tmp->idhnext != client_p)
        if ((tmp = tmp->idhnext) == NULL)
          return;

      tmp->idhnext = tmp->idhnext->idhnext;
      client_p->idhnext = client_p;
    }
  }
}

/* hash_del_client()
 *
 * inputs       - pointer to client
 * output       - NONE
 * side effects - Removes a Client's name from the hash linked list
 */
void
hash_del_client(struct Client *client_p)
{
  const unsigned int hashv = strhash(client_p->name);
  struct Client *tmp = clientTable[hashv];

  if (tmp)
  {
    if (tmp == client_p)
    {
      clientTable[hashv] = client_p->hnext;
      client_p->hnext = client_p;
    }
    else
    {
      while (tmp->hnext != client_p)
        if ((tmp = tmp->hnext) == NULL)
          return;

      tmp->hnext = tmp->hnext->hnext;
      client_p->hnext = client_p;
    }
  }
}

/* hash_del_userhost()
 *
 * inputs       - pointer to userhost
 * output       - NONE
 * side effects - Removes a userhost from the hash linked list
 */
void
hash_del_userhost(struct UserHost *userhost)
{
  const unsigned int hashv = strhash(userhost->host);
  struct UserHost *tmp = userhostTable[hashv];

  if (tmp)
  {
    if (tmp == userhost)
    {
      userhostTable[hashv] = userhost->next;
      userhost->next = userhost;
    }
    else
    {
      while (tmp->next != userhost)
        if ((tmp = tmp->next) == NULL)
          return;

      tmp->next = tmp->next->next;
      userhost->next = userhost;
    }
  }
}

/* hash_del_channel()
 *
 * inputs       - pointer to client
 * output       - NONE
 * side effects - Removes the channel's name from the corresponding
 *                hash linked list
 */
void
hash_del_channel(struct Channel *chptr)
{
  const unsigned int hashv = strhash(chptr->name);
  struct Channel *tmp = channelTable[hashv];

  if (tmp)
  {
    if (tmp == chptr)
    {
      channelTable[hashv] = chptr->hnextch;
      chptr->hnextch = chptr;
    }
    else
    {
      while (tmp->hnextch != chptr)
        if ((tmp = tmp->hnextch) == NULL)
          return;

      tmp->hnextch = tmp->hnextch->hnextch;
      chptr->hnextch = chptr;
    }
  }
}

/* hash_find_client()
 *
 * inputs       - pointer to name
 * output       - NONE
 * side effects - New semantics: finds a client whose name is 'name'
 *                if can't find one returns NULL. If it finds one moves
 *                it to the top of the list and returns it.
 */
struct Client *
hash_find_client(const char *name)
{
  const unsigned int hashv = strhash(name);
  struct Client *client_p;

  if ((client_p = clientTable[hashv]))
  {
    if (irccmp(name, client_p->name))
    {
      struct Client *prev;

      while (prev = client_p, (client_p = client_p->hnext))
      {
        if (!irccmp(name, client_p->name))
        {
          prev->hnext = client_p->hnext;
          client_p->hnext = clientTable[hashv];
          clientTable[hashv] = client_p;
          break;
        }
      }
    }
  }

  return client_p;
}

struct Client *
hash_find_id(const char *name)
{
  const unsigned int hashv = strhash(name);
  struct Client *client_p;

  if ((client_p = idTable[hashv]))
  {
    if (strcmp(name, client_p->id))
    {
      struct Client *prev;

      while (prev = client_p, (client_p = client_p->idhnext))
      {
        if (!strcmp(name, client_p->id))
        {
          prev->idhnext = client_p->idhnext;
          client_p->idhnext = idTable[hashv];
          idTable[hashv] = client_p;
          break;
        }
      }
    }
  }

  return client_p;
}

struct Client *
hash_find_server(const char *name)
{
  const unsigned int hashv = strhash(name);
  struct Client *client_p = NULL;

  if (IsDigit(*name) && strlen(name) == IRC_MAXSID)
    return hash_find_id(name);

  if ((client_p = clientTable[hashv]))
  {
    if ((!IsServer(client_p) && !IsMe(client_p)) ||
        irccmp(name, client_p->name))
    {
      struct Client *prev;

      while (prev = client_p, (client_p = client_p->hnext))
      {
        if ((IsServer(client_p) || IsMe(client_p)) &&
            !irccmp(name, client_p->name))
        {
          prev->hnext = client_p->hnext;
          client_p->hnext = clientTable[hashv];
          clientTable[hashv] = client_p;
          break;
        }
      }
    }
  }

  return client_p;
}

/* hash_find_channel()
 *
 * inputs       - pointer to name
 * output       - NONE
 * side effects - New semantics: finds a channel whose name is 'name',
 *                if can't find one returns NULL, if can find it moves
 *                it to the top of the list and returns it.
 */
struct Channel *
hash_find_channel(const char *name)
{
  const unsigned int hashv = strhash(name);
  struct Channel *chptr = NULL;

  if ((chptr = channelTable[hashv]))
  {
    if (irccmp(name, chptr->name))
    {
      struct Channel *prev;

      while (prev = chptr, (chptr = chptr->hnextch))
      {
        if (!irccmp(name, chptr->name))
        {
          prev->hnextch = chptr->hnextch;
          chptr->hnextch = channelTable[hashv];
          channelTable[hashv] = chptr;
          break;
        }
      }
    }
  }

  return chptr;
}

struct UserHost *
hash_find_userhost(const char *host)
{
  const unsigned int hashv = strhash(host);
  struct UserHost *userhost;

  if ((userhost = userhostTable[hashv]))
  {
    if (irccmp(host, userhost->host))
    {
      struct UserHost *prev;

      while (prev = userhost, (userhost = userhost->next))
      {
        if (!irccmp(host, userhost->host))
        {
          prev->next = userhost->next;
          userhost->next = userhostTable[hashv];
          userhostTable[hashv] = userhost;
          break;
        }
      }
    }
  }

  return userhost;
}

/* hash_get_bucket(int type, unsigned int hashv)
 *
 * inputs       - hash value (must be between 0 and HASHSIZE - 1)
 * output       - NONE
 * returns      - pointer to first channel in channelTable[hashv]
 *                if that exists;
 *                NULL if there is no channel in that place;
 *                NULL if hashv is an invalid number.
 * side effects - NONE
 */
void *
hash_get_bucket(int type, unsigned int hashv)
{
  assert(hashv < HASHSIZE);

  if (hashv >= HASHSIZE)
    return NULL;

  switch (type)
  {
    case HASH_TYPE_ID:
      return idTable[hashv];
      break;
    case HASH_TYPE_CHANNEL:
      return channelTable[hashv];
      break;
    case HASH_TYPE_CLIENT:
      return clientTable[hashv];
      break;
    case HASH_TYPE_USERHOST:
      return userhostTable[hashv];
      break;
    default:
      assert(0);
  }

  return NULL;
}

/*
 * Safe list code.
 *
 * The idea is really quite simple. As the link lists pointed to in
 * each "bucket" of the channel hash table are traversed atomically
 * there is no locking needed. Overall, yes, inconsistent reported
 * state can still happen, but normally this isn't a big deal.
 * I don't like sticking the code into hash.c but oh well. Moreover,
 * if a hash isn't used in future, oops.
 *
 * - Dianora
 */

/* exceeding_sendq()
 *
 * inputs       - pointer to client to check
 * output       - 1 if client is in danger of blowing its sendq
 *                0 if it is not.
 * side effects -
 *
 * Sendq limit is fairly conservative at 1/2 (In original anyway)
 */
static int
exceeding_sendq(const struct Client *to)
{
  if (dbuf_length(&to->connection->buf_sendq) > (get_sendq(&to->connection->confs) / 2))
    return 1;
  else
    return 0;
}

void
free_list_task(struct Client *source_p)
{
  struct ListTask *const lt = source_p->connection->list_task;
  dlink_node *node = NULL, *node_next = NULL;

  dlinkDelete(&lt->node, &listing_client_list);

  DLINK_FOREACH_SAFE(node, node_next, lt->show_mask.head)
  {
    xfree(node->data);
    free_dlink_node(node);
  }

  DLINK_FOREACH_SAFE(node, node_next, lt->hide_mask.head)
  {
    xfree(node->data);
    free_dlink_node(node);
  }

  xfree(lt);
  source_p->connection->list_task = NULL;
}

/* list_allow_channel()
 *
 * inputs       - channel name
 *              - pointer to a list task
 * output       - 1 if the channel is to be displayed
 *                0 otherwise
 * side effects -
 */
static int
list_allow_channel(const char *name, const struct ListTask *lt)
{
  const dlink_node *node = NULL;

  DLINK_FOREACH(node, lt->show_mask.head)
    if (match(node->data, name) != 0)
      return 0;

  DLINK_FOREACH(node, lt->hide_mask.head)
    if (match(node->data, name) == 0)
      return 0;

  return 1;
}

/* list_one_channel()
 *
 * inputs       - client pointer to return result to
 *              - pointer to channel to list
 *              - pointer to ListTask structure
 * output       - none
 * side effects -
 */
static void
list_one_channel(struct Client *source_p, struct Channel *chptr)
{
  const struct ListTask *const lt = source_p->connection->list_task;
  char listbuf[MODEBUFLEN] = "";
  char modebuf[MODEBUFLEN] = "";
  char parabuf[MODEBUFLEN] = "";

  if (SecretChannel(chptr) &&
      !(HasUMode(source_p, UMODE_ADMIN) || IsMember(source_p, chptr)))
    return;

  if (dlink_list_length(&chptr->members) < lt->users_min ||
      dlink_list_length(&chptr->members) > lt->users_max ||
      (chptr->creationtime != 0 &&
       ((unsigned int)chptr->creationtime < lt->created_min ||
        (unsigned int)chptr->creationtime > lt->created_max)) ||
      (unsigned int)chptr->topic_time < lt->topicts_min ||
      (chptr->topic_time ? (unsigned int)chptr->topic_time : UINT_MAX) >
      lt->topicts_max)
    return;

  if (lt->topic[0] && match(lt->topic, chptr->topic))
    return;

  if (!list_allow_channel(chptr->name, lt))
    return;

  channel_modes(chptr, source_p, modebuf, parabuf);

  if (chptr->topic[0])
    snprintf(listbuf, sizeof(listbuf), "[%s] ", modebuf);
  else
    snprintf(listbuf, sizeof(listbuf), "[%s]",  modebuf);

  sendto_one_numeric(source_p, &me, RPL_LIST, chptr->name,
                     dlink_list_length(&chptr->members),
                     listbuf, chptr->topic);
}

/* safe_list_channels()
 *
 * inputs       - pointer to client requesting list
 * output       - 0/1
 * side effects - safely list all channels to source_p
 *
 * Walk the channel buckets, ensure all pointers in a bucket are
 * traversed before blocking on a sendq. This means, no locking is needed.
 *
 * - Dianora
 */
void
safe_list_channels(struct Client *source_p, int only_unmasked_channels)
{
  struct ListTask *const lt = source_p->connection->list_task;
  struct Channel *chptr = NULL;

  if (!only_unmasked_channels)
  {
    for (unsigned int i = lt->hash_index; i < HASHSIZE; ++i)
    {
      if (exceeding_sendq(source_p))
      {
        lt->hash_index = i;
        return;  /* Still more to do */
      }

      for (chptr = channelTable[i]; chptr; chptr = chptr->hnextch)
        list_one_channel(source_p, chptr);
    }
  }
  else
  {
    dlink_node *node = NULL;

    DLINK_FOREACH(node, lt->show_mask.head)
      if ((chptr = hash_find_channel(node->data)))
        list_one_channel(source_p, chptr);
  }

  free_list_task(source_p);
  sendto_one_numeric(source_p, &me, RPL_LISTEND);
}
Revision:	7032
Committed:	Sun Jan 3 14:34:39 2016 UTC (9 years, 7 months ago) by michael
Content type:	text/x-csrc
File size:	16163 byte(s)
Log Message:	- Renamed MyCalloc to xcalloc
#	Content
1	/*
2	* ircd-hybrid: an advanced, lightweight Internet Relay Chat Daemon (ircd)
3	*
4	* Copyright (c) 1997-2016 ircd-hybrid development team
5	*
6	* This program is free software; you can redistribute it and/or modify
7	* it under the terms of the GNU General Public License as published by
8	* the Free Software Foundation; either version 2 of the License, or
9	* (at your option) any later version.
10	*
11	* This program is distributed in the hope that it will be useful,
12	* but WITHOUT ANY WARRANTY; without even the implied warranty of
13	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14	* GNU General Public License for more details.
15	*
16	* You should have received a copy of the GNU General Public License
17	* along with this program; if not, write to the Free Software
18	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301
19	* USA
20	*/
21
22	/*! \file hash.c
23	* \brief Hash table management.
24	* \version $Id$
25	*/
26
27	#include "stdinc.h"
28	#include "list.h"
29	#include "conf.h"
30	#include "channel.h"
31	#include "channel_mode.h"
32	#include "client.h"
33	#include "modules.h"
34	#include "hash.h"
35	#include "id.h"
36	#include "resv.h"
37	#include "rng_mt.h"
38	#include "userhost.h"
39	#include "irc_string.h"
40	#include "ircd.h"
41	#include "numeric.h"
42	#include "send.h"
43	#include "memory.h"
44	#include "mempool.h"
45	#include "dbuf.h"
46	#include "user.h"
47
48
49	static unsigned int hashf_xor_key;
50
51	/* The actual hash tables, They MUST be of the same HASHSIZE, variable
52	* size tables could be supported but the rehash routine should also
53	* rebuild the transformation maps, I kept the tables of equal size
54	* so that I can use one hash function.
55	*/
56	static struct Client *idTable[HASHSIZE];
57	static struct Client *clientTable[HASHSIZE];
58	static struct Channel *channelTable[HASHSIZE];
59	static struct UserHost *userhostTable[HASHSIZE];
60
61
62	/* hash_init()
63	*
64	* inputs - NONE
65	* output - NONE
66	* side effects - Initialize the maps used by hash
67	* functions and clear the tables
68	*/
69	void
70	hash_init(void)
71	{
72	do
73	hashf_xor_key = genrand_int32() % 256; /* better than nothing --adx */
74	while (!hashf_xor_key);
75	}
76
77	/*
78	* New hash function based on the Fowler/Noll/Vo (FNV) algorithm from
79	* http://www.isthe.com/chongo/tech/comp/fnv/
80	*
81	* Here, we use the FNV-1 method, which gives slightly better results
82	* than FNV-1a. -Michael
83	*/
84	unsigned int
85	strhash(const char *name)
86	{
87	const unsigned char p = (const unsigned char )name;
88	unsigned int hval = FNV1_32_INIT;
89
90	if (EmptyString(p))
91	return 0;
92
93	for (; *p; ++p)
94	{
95	hval += (hval << 1) + (hval << 4) + (hval << 7) +
96	(hval << 8) + (hval << 24);
97	hval ^= (ToLower(*p) ^ hashf_xor_key);
98	}
99
100	return (hval >> FNV1_32_BITS) ^ (hval & ((1 << FNV1_32_BITS) - 1));
101	}
102
103	/************************ Externally visible functions ******************/
104
105	/* Optimization note: in these functions I supposed that the CSE optimization
106	* (Common Subexpression Elimination) does its work decently, this means that
107	* I avoided introducing new variables to do the work myself and I did let
108	* the optimizer play with more free registers, actual tests proved this
109	* solution to be faster than doing things like tmp2=tmp->hnext... and then
110	* use tmp2 myself which would have given less freedom to the optimizer.
111	*/
112
113	/* hash_add_client()
114	*
115	* inputs - pointer to client
116	* output - NONE
117	* side effects - Adds a client's name in the proper hash linked
118	* list, can't fail, client_p must have a non-null
119	* name or expect a coredump, the name is infact
120	* taken from client_p->name
121	*/
122	void
123	hash_add_client(struct Client *client_p)
124	{
125	const unsigned int hashv = strhash(client_p->name);
126
127	client_p->hnext = clientTable[hashv];
128	clientTable[hashv] = client_p;
129	}
130
131	/* hash_add_channel()
132	*
133	* inputs - pointer to channel
134	* output - NONE
135	* side effects - Adds a channel's name in the proper hash linked
136	* list, can't fail. chptr must have a non-null name
137	* or expect a coredump. As before the name is taken
138	* from chptr->name, we do hash its entire lenght
139	* since this proved to be statistically faster
140	*/
141	void
142	hash_add_channel(struct Channel *chptr)
143	{
144	const unsigned int hashv = strhash(chptr->name);
145
146	chptr->hnextch = channelTable[hashv];
147	channelTable[hashv] = chptr;
148	}
149
150	void
151	hash_add_userhost(struct UserHost *userhost)
152	{
153	const unsigned int hashv = strhash(userhost->host);
154
155	userhost->next = userhostTable[hashv];
156	userhostTable[hashv] = userhost;
157	}
158
159	void
160	hash_add_id(struct Client *client_p)
161	{
162	const unsigned int hashv = strhash(client_p->id);
163
164	client_p->idhnext = idTable[hashv];
165	idTable[hashv] = client_p;
166	}
167
168	/* hash_del_id()
169	*
170	* inputs - pointer to client
171	* output - NONE
172	* side effects - Removes an ID from the hash linked list
173	*/
174	void
175	hash_del_id(struct Client *client_p)
176	{
177	const unsigned int hashv = strhash(client_p->id);
178	struct Client *tmp = idTable[hashv];
179
180	if (tmp)
181	{
182	if (tmp == client_p)
183	{
184	idTable[hashv] = client_p->idhnext;
185	client_p->idhnext = client_p;
186	}
187	else
188	{
189	while (tmp->idhnext != client_p)
190	if ((tmp = tmp->idhnext) == NULL)
191	return;
192
193	tmp->idhnext = tmp->idhnext->idhnext;
194	client_p->idhnext = client_p;
195	}
196	}
197	}
198
199	/* hash_del_client()
200	*
201	* inputs - pointer to client
202	* output - NONE
203	* side effects - Removes a Client's name from the hash linked list
204	*/
205	void
206	hash_del_client(struct Client *client_p)
207	{
208	const unsigned int hashv = strhash(client_p->name);
209	struct Client *tmp = clientTable[hashv];
210
211	if (tmp)
212	{
213	if (tmp == client_p)
214	{
215	clientTable[hashv] = client_p->hnext;
216	client_p->hnext = client_p;
217	}
218	else
219	{
220	while (tmp->hnext != client_p)
221	if ((tmp = tmp->hnext) == NULL)
222	return;
223
224	tmp->hnext = tmp->hnext->hnext;
225	client_p->hnext = client_p;
226	}
227	}
228	}
229
230	/* hash_del_userhost()
231	*
232	* inputs - pointer to userhost
233	* output - NONE
234	* side effects - Removes a userhost from the hash linked list
235	*/
236	void
237	hash_del_userhost(struct UserHost *userhost)
238	{
239	const unsigned int hashv = strhash(userhost->host);
240	struct UserHost *tmp = userhostTable[hashv];
241
242	if (tmp)
243	{
244	if (tmp == userhost)
245	{
246	userhostTable[hashv] = userhost->next;
247	userhost->next = userhost;
248	}
249	else
250	{
251	while (tmp->next != userhost)
252	if ((tmp = tmp->next) == NULL)
253	return;
254
255	tmp->next = tmp->next->next;
256	userhost->next = userhost;
257	}
258	}
259	}
260
261	/* hash_del_channel()
262	*
263	* inputs - pointer to client
264	* output - NONE
265	* side effects - Removes the channel's name from the corresponding
266	* hash linked list
267	*/
268	void
269	hash_del_channel(struct Channel *chptr)
270	{
271	const unsigned int hashv = strhash(chptr->name);
272	struct Channel *tmp = channelTable[hashv];
273
274	if (tmp)
275	{
276	if (tmp == chptr)
277	{
278	channelTable[hashv] = chptr->hnextch;
279	chptr->hnextch = chptr;
280	}
281	else
282	{
283	while (tmp->hnextch != chptr)
284	if ((tmp = tmp->hnextch) == NULL)
285	return;
286
287	tmp->hnextch = tmp->hnextch->hnextch;
288	chptr->hnextch = chptr;
289	}
290	}
291	}
292
293	/* hash_find_client()
294	*
295	* inputs - pointer to name
296	* output - NONE
297	* side effects - New semantics: finds a client whose name is 'name'
298	* if can't find one returns NULL. If it finds one moves
299	* it to the top of the list and returns it.
300	*/
301	struct Client *
302	hash_find_client(const char *name)
303	{
304	const unsigned int hashv = strhash(name);
305	struct Client *client_p;
306
307	if ((client_p = clientTable[hashv]))
308	{
309	if (irccmp(name, client_p->name))
310	{
311	struct Client *prev;
312
313	while (prev = client_p, (client_p = client_p->hnext))
314	{
315	if (!irccmp(name, client_p->name))
316	{
317	prev->hnext = client_p->hnext;
318	client_p->hnext = clientTable[hashv];
319	clientTable[hashv] = client_p;
320	break;
321	}
322	}
323	}
324	}
325
326	return client_p;
327	}
328
329	struct Client *
330	hash_find_id(const char *name)
331	{
332	const unsigned int hashv = strhash(name);
333	struct Client *client_p;
334
335	if ((client_p = idTable[hashv]))
336	{
337	if (strcmp(name, client_p->id))
338	{
339	struct Client *prev;
340
341	while (prev = client_p, (client_p = client_p->idhnext))
342	{
343	if (!strcmp(name, client_p->id))
344	{
345	prev->idhnext = client_p->idhnext;
346	client_p->idhnext = idTable[hashv];
347	idTable[hashv] = client_p;
348	break;
349	}
350	}
351	}
352	}
353
354	return client_p;
355	}
356
357	struct Client *
358	hash_find_server(const char *name)
359	{
360	const unsigned int hashv = strhash(name);
361	struct Client *client_p = NULL;
362
363	if (IsDigit(*name) && strlen(name) == IRC_MAXSID)
364	return hash_find_id(name);
365
366	if ((client_p = clientTable[hashv]))
367	{
368	if ((!IsServer(client_p) && !IsMe(client_p)) \|\|
369	irccmp(name, client_p->name))
370	{
371	struct Client *prev;
372
373	while (prev = client_p, (client_p = client_p->hnext))
374	{
375	if ((IsServer(client_p) \|\| IsMe(client_p)) &&
376	!irccmp(name, client_p->name))
377	{
378	prev->hnext = client_p->hnext;
379	client_p->hnext = clientTable[hashv];
380	clientTable[hashv] = client_p;
381	break;
382	}
383	}
384	}
385	}
386
387	return client_p;
388	}
389
390	/* hash_find_channel()
391	*
392	* inputs - pointer to name
393	* output - NONE
394	* side effects - New semantics: finds a channel whose name is 'name',
395	* if can't find one returns NULL, if can find it moves
396	* it to the top of the list and returns it.
397	*/
398	struct Channel *
399	hash_find_channel(const char *name)
400	{
401	const unsigned int hashv = strhash(name);
402	struct Channel *chptr = NULL;
403
404	if ((chptr = channelTable[hashv]))
405	{
406	if (irccmp(name, chptr->name))
407	{
408	struct Channel *prev;
409
410	while (prev = chptr, (chptr = chptr->hnextch))
411	{
412	if (!irccmp(name, chptr->name))
413	{
414	prev->hnextch = chptr->hnextch;
415	chptr->hnextch = channelTable[hashv];
416	channelTable[hashv] = chptr;
417	break;
418	}
419	}
420	}
421	}
422
423	return chptr;
424	}
425
426	struct UserHost *
427	hash_find_userhost(const char *host)
428	{
429	const unsigned int hashv = strhash(host);
430	struct UserHost *userhost;
431
432	if ((userhost = userhostTable[hashv]))
433	{
434	if (irccmp(host, userhost->host))
435	{
436	struct UserHost *prev;
437
438	while (prev = userhost, (userhost = userhost->next))
439	{
440	if (!irccmp(host, userhost->host))
441	{
442	prev->next = userhost->next;
443	userhost->next = userhostTable[hashv];
444	userhostTable[hashv] = userhost;
445	break;
446	}
447	}
448	}
449	}
450
451	return userhost;
452	}
453
454	/* hash_get_bucket(int type, unsigned int hashv)
455	*
456	* inputs - hash value (must be between 0 and HASHSIZE - 1)
457	* output - NONE
458	* returns - pointer to first channel in channelTable[hashv]
459	* if that exists;
460	* NULL if there is no channel in that place;
461	* NULL if hashv is an invalid number.
462	* side effects - NONE
463	*/
464	void *
465	hash_get_bucket(int type, unsigned int hashv)
466	{
467	assert(hashv < HASHSIZE);
468
469	if (hashv >= HASHSIZE)
470	return NULL;
471
472	switch (type)
473	{
474	case HASH_TYPE_ID:
475	return idTable[hashv];
476	break;
477	case HASH_TYPE_CHANNEL:
478	return channelTable[hashv];
479	break;
480	case HASH_TYPE_CLIENT:
481	return clientTable[hashv];
482	break;
483	case HASH_TYPE_USERHOST:
484	return userhostTable[hashv];
485	break;
486	default:
487	assert(0);
488	}
489
490	return NULL;
491	}
492
493	/*
494	* Safe list code.
495	*
496	* The idea is really quite simple. As the link lists pointed to in
497	* each "bucket" of the channel hash table are traversed atomically
498	* there is no locking needed. Overall, yes, inconsistent reported
499	* state can still happen, but normally this isn't a big deal.
500	* I don't like sticking the code into hash.c but oh well. Moreover,
501	* if a hash isn't used in future, oops.
502	*
503	* - Dianora
504	*/
505
506	/* exceeding_sendq()
507	*
508	* inputs - pointer to client to check
509	* output - 1 if client is in danger of blowing its sendq
510	* 0 if it is not.
511	* side effects -
512	*
513	* Sendq limit is fairly conservative at 1/2 (In original anyway)
514	*/
515	static int
516	exceeding_sendq(const struct Client *to)
517	{
518	if (dbuf_length(&to->connection->buf_sendq) > (get_sendq(&to->connection->confs) / 2))
519	return 1;
520	else
521	return 0;
522	}
523
524	void
525	free_list_task(struct Client *source_p)
526	{
527	struct ListTask *const lt = source_p->connection->list_task;
528	dlink_node node = NULL, node_next = NULL;
529
530	dlinkDelete(&lt->node, &listing_client_list);
531
532	DLINK_FOREACH_SAFE(node, node_next, lt->show_mask.head)
533	{
534	xfree(node->data);
535	free_dlink_node(node);
536	}
537
538	DLINK_FOREACH_SAFE(node, node_next, lt->hide_mask.head)
539	{
540	xfree(node->data);
541	free_dlink_node(node);
542	}
543
544	xfree(lt);
545	source_p->connection->list_task = NULL;
546	}
547
548	/* list_allow_channel()
549	*
550	* inputs - channel name
551	* - pointer to a list task
552	* output - 1 if the channel is to be displayed
553	* 0 otherwise
554	* side effects -
555	*/
556	static int
557	list_allow_channel(const char name, const struct ListTask lt)
558	{
559	const dlink_node *node = NULL;
560
561	DLINK_FOREACH(node, lt->show_mask.head)
562	if (match(node->data, name) != 0)
563	return 0;
564
565	DLINK_FOREACH(node, lt->hide_mask.head)
566	if (match(node->data, name) == 0)
567	return 0;
568
569	return 1;
570	}
571
572	/* list_one_channel()
573	*
574	* inputs - client pointer to return result to
575	* - pointer to channel to list
576	* - pointer to ListTask structure
577	* output - none
578	* side effects -
579	*/
580	static void
581	list_one_channel(struct Client source_p, struct Channel chptr)
582	{
583	const struct ListTask *const lt = source_p->connection->list_task;
584	char listbuf[MODEBUFLEN] = "";
585	char modebuf[MODEBUFLEN] = "";
586	char parabuf[MODEBUFLEN] = "";
587
588	if (SecretChannel(chptr) &&
589	!(HasUMode(source_p, UMODE_ADMIN) \|\| IsMember(source_p, chptr)))
590	return;
591
592	if (dlink_list_length(&chptr->members) < lt->users_min \|\|
593	dlink_list_length(&chptr->members) > lt->users_max \|\|
594	(chptr->creationtime != 0 &&
595	((unsigned int)chptr->creationtime < lt->created_min \|\|
596	(unsigned int)chptr->creationtime > lt->created_max)) \|\|
597	(unsigned int)chptr->topic_time < lt->topicts_min \|\|
598	(chptr->topic_time ? (unsigned int)chptr->topic_time : UINT_MAX) >
599	lt->topicts_max)
600	return;
601
602	if (lt->topic[0] && match(lt->topic, chptr->topic))
603	return;
604
605	if (!list_allow_channel(chptr->name, lt))
606	return;
607
608	channel_modes(chptr, source_p, modebuf, parabuf);
609
610	if (chptr->topic[0])
611	snprintf(listbuf, sizeof(listbuf), "[%s] ", modebuf);
612	else
613	snprintf(listbuf, sizeof(listbuf), "[%s]", modebuf);
614
615	sendto_one_numeric(source_p, &me, RPL_LIST, chptr->name,
616	dlink_list_length(&chptr->members),
617	listbuf, chptr->topic);
618	}
619
620	/* safe_list_channels()
621	*
622	* inputs - pointer to client requesting list
623	* output - 0/1
624	* side effects - safely list all channels to source_p
625	*
626	* Walk the channel buckets, ensure all pointers in a bucket are
627	* traversed before blocking on a sendq. This means, no locking is needed.
628	*
629	* - Dianora
630	*/
631	void
632	safe_list_channels(struct Client *source_p, int only_unmasked_channels)
633	{
634	struct ListTask *const lt = source_p->connection->list_task;
635	struct Channel *chptr = NULL;
636
637	if (!only_unmasked_channels)
638	{
639	for (unsigned int i = lt->hash_index; i < HASHSIZE; ++i)
640	{
641	if (exceeding_sendq(source_p))
642	{
643	lt->hash_index = i;
644	return; /* Still more to do */
645	}
646
647	for (chptr = channelTable[i]; chptr; chptr = chptr->hnextch)
648	list_one_channel(source_p, chptr);
649	}
650	}
651	else
652	{
653	dlink_node *node = NULL;
654
655	DLINK_FOREACH(node, lt->show_mask.head)
656	if ((chptr = hash_find_channel(node->data)))
657	list_one_channel(source_p, chptr);
658	}
659
660	free_list_task(source_p);
661	sendto_one_numeric(source_p, &me, RPL_LISTEND);
662	}