[svn] Fix some cases where the size argument to strlcpy()

[irc/rqf/shadowircd.git] / src / channel.c

/*
 *  ircd-ratbox: A slightly useful ircd.
 *  channel.c: Controls channels.
 *
 * Copyright (C) 1990 Jarkko Oikarinen and University of Oulu, Co Center 
 * Copyright (C) 1996-2002 Hybrid Development Team 
 * Copyright (C) 2002-2005 ircd-ratbox 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307
 *  USA
 *
 *  $Id: channel.c 3173 2007-01-31 23:57:18Z jilles $
 */

#include "stdinc.h"
#include "tools.h"
#include "channel.h"
#include "client.h"
#include "common.h"
#include "hash.h"
#include "hook.h"
#include "irc_string.h"
#include "sprintf_irc.h"
#include "ircd.h"
#include "numeric.h"
#include "s_serv.h"             /* captab */
#include "s_user.h"
#include "send.h"
#include "whowas.h"
#include "s_conf.h"             /* ConfigFileEntry, ConfigChannel */
#include "s_newconf.h"
#include "event.h"
#include "memory.h"
#include "balloc.h"
#include "s_log.h"

extern dlink_list global_channel_list;

extern struct config_channel_entry ConfigChannel;
extern BlockHeap *channel_heap;
extern BlockHeap *ban_heap;
extern BlockHeap *topic_heap;
extern BlockHeap *member_heap;

static int channel_capabs[] = { CAP_EX, CAP_IE,
        CAP_SERVICE,
        CAP_TS6
};

#define NCHCAPS         (sizeof(channel_capabs)/sizeof(int))
#define NCHCAP_COMBOS   (1 << NCHCAPS)

static struct ChCapCombo chcap_combos[NCHCAP_COMBOS];

static void free_topic(struct Channel *chptr);

static int h_can_join;

/* init_channels()
 *
 * input        -
 * output       -
 * side effects - initialises the various blockheaps
 */
void
init_channels(void)
{
        channel_heap = BlockHeapCreate(sizeof(struct Channel), CHANNEL_HEAP_SIZE);
        ban_heap = BlockHeapCreate(sizeof(struct Ban), BAN_HEAP_SIZE);
        topic_heap = BlockHeapCreate(TOPICLEN + 1 + USERHOST_REPLYLEN, TOPIC_HEAP_SIZE);
        member_heap = BlockHeapCreate(sizeof(struct membership), MEMBER_HEAP_SIZE);

        h_can_join = register_hook("can_join");
}

/*
 * allocate_channel - Allocates a channel
 */
struct Channel *
allocate_channel(const char *chname)
{
        struct Channel *chptr;
        chptr = BlockHeapAlloc(channel_heap);
        DupNString(chptr->chname, chname, CHANNELLEN);
        return (chptr);
}

void
free_channel(struct Channel *chptr)
{
        MyFree(chptr->chname);
        BlockHeapFree(channel_heap, chptr);
}

struct Ban *
allocate_ban(const char *banstr, const char *who)
{
        struct Ban *bptr;
        bptr = BlockHeapAlloc(ban_heap);
        DupNString(bptr->banstr, banstr, BANLEN);
        DupNString(bptr->who, who, BANLEN);

        return (bptr);
}

void
free_ban(struct Ban *bptr)
{
        MyFree(bptr->banstr);
        MyFree(bptr->who);
        BlockHeapFree(ban_heap, bptr);
}


/* find_channel_membership()
 *
 * input        - channel to find them in, client to find
 * output       - membership of client in channel, else NULL
 * side effects -
 */
struct membership *
find_channel_membership(struct Channel *chptr, struct Client *client_p)
{
        struct membership *msptr;
        dlink_node *ptr;

        if(!IsClient(client_p))
                return NULL;

        /* Pick the most efficient list to use to be nice to things like
         * CHANSERV which could be in a large number of channels
         */
        if(dlink_list_length(&chptr->members) < dlink_list_length(&client_p->user->channel))
        {
                DLINK_FOREACH(ptr, chptr->members.head)
                {
                        msptr = ptr->data;

                        if(msptr->client_p == client_p)
                                return msptr;
                }
        }
        else
        {
                DLINK_FOREACH(ptr, client_p->user->channel.head)
                {
                        msptr = ptr->data;

                        if(msptr->chptr == chptr)
                                return msptr;
                }
        }

        return NULL;
}

/* find_channel_status()
 *
 * input        - membership to get status for, whether we can combine flags
 * output       - flags of user on channel
 * side effects -
 */
const char *
find_channel_status(struct membership *msptr, int combine)
{
        static char buffer[3];
        char *p;

        p = buffer;

        if(is_chanop(msptr))
        {
                if(!combine)
                        return "@";
                *p++ = '@';
        }

        if(is_voiced(msptr))
                *p++ = '+';

        *p = '\0';
        return buffer;
}

/* add_user_to_channel()
 *
 * input        - channel to add client to, client to add, channel flags
 * output       - 
 * side effects - user is added to channel
 */
void
add_user_to_channel(struct Channel *chptr, struct Client *client_p, int flags)
{
        struct membership *msptr;

        s_assert(client_p->user != NULL);
        if(client_p->user == NULL)
                return;

        msptr = BlockHeapAlloc(member_heap);

        msptr->chptr = chptr;
        msptr->client_p = client_p;
        msptr->flags = flags;

        dlinkAdd(msptr, &msptr->usernode, &client_p->user->channel);
        dlinkAdd(msptr, &msptr->channode, &chptr->members);

        if(MyClient(client_p))
                dlinkAdd(msptr, &msptr->locchannode, &chptr->locmembers);
}

/* remove_user_from_channel()
 *
 * input        - membership pointer to remove from channel
 * output       -
 * side effects - membership (thus user) is removed from channel
 */
void
remove_user_from_channel(struct membership *msptr)
{
        struct Client *client_p;
        struct Channel *chptr;
        s_assert(msptr != NULL);
        if(msptr == NULL)
                return;

        client_p = msptr->client_p;
        chptr = msptr->chptr;

        dlinkDelete(&msptr->usernode, &client_p->user->channel);
        dlinkDelete(&msptr->channode, &chptr->members);

        if(client_p->servptr == &me)
                dlinkDelete(&msptr->locchannode, &chptr->locmembers);

        chptr->users_last = CurrentTime;

        if(!(chptr->mode.mode & MODE_PERMANENT) && dlink_list_length(&chptr->members) <= 0)
                destroy_channel(chptr);

        BlockHeapFree(member_heap, msptr);

        return;
}

/* remove_user_from_channels()
 *
 * input        - user to remove from all channels
 * output       -
 * side effects - user is removed from all channels
 */
void
remove_user_from_channels(struct Client *client_p)
{
        struct Channel *chptr;
        struct membership *msptr;
        dlink_node *ptr;
        dlink_node *next_ptr;

        if(client_p == NULL)
                return;

        DLINK_FOREACH_SAFE(ptr, next_ptr, client_p->user->channel.head)
        {
                msptr = ptr->data;
                chptr = msptr->chptr;

                dlinkDelete(&msptr->channode, &chptr->members);

                if(client_p->servptr == &me)
                        dlinkDelete(&msptr->locchannode, &chptr->locmembers);

                chptr->users_last = CurrentTime;

                if(!(chptr->mode.mode & MODE_PERMANENT) && dlink_list_length(&chptr->members) <= 0)
                        destroy_channel(chptr);

                BlockHeapFree(member_heap, msptr);
        }

        client_p->user->channel.head = client_p->user->channel.tail = NULL;
        client_p->user->channel.length = 0;
}

/* invalidate_bancache_user()
 *
 * input        - user to invalidate ban cache for
 * output       -
 * side effects - ban cache is invalidated for all memberships of that user
 *                to be used after a nick change
 */
void
invalidate_bancache_user(struct Client *client_p)
{
        struct membership *msptr;
        dlink_node *ptr;

        if(client_p == NULL)
                return;

        DLINK_FOREACH(ptr, client_p->user->channel.head)
        {
                msptr = ptr->data;
                msptr->bants = 0;
                msptr->flags &= ~CHFL_BANNED;
        }
}

/* check_channel_name()
 *
 * input        - channel name
 * output       - 1 if valid channel name, else 0
 * side effects -
 */
int
check_channel_name(const char *name)
{
        s_assert(name != NULL);
        if(name == NULL)
                return 0;

        for (; *name; ++name)
        {
                if(!IsChanChar(*name))
                        return 0;
        }

        return 1;
}

/* free_channel_list()
 *
 * input        - dlink list to free
 * output       -
 * side effects - list of b/e/I modes is cleared
 */
void
free_channel_list(dlink_list * list)
{
        dlink_node *ptr;
        dlink_node *next_ptr;
        struct Ban *actualBan;

        DLINK_FOREACH_SAFE(ptr, next_ptr, list->head)
        {
                actualBan = ptr->data;
                free_ban(actualBan);
        }

        list->head = list->tail = NULL;
        list->length = 0;
}

/* destroy_channel()
 *
 * input        - channel to destroy
 * output       -
 * side effects - channel is obliterated
 */
void
destroy_channel(struct Channel *chptr)
{
        dlink_node *ptr, *next_ptr;

        DLINK_FOREACH_SAFE(ptr, next_ptr, chptr->invites.head)
        {
                del_invite(chptr, ptr->data);
        }

        /* free all bans/exceptions/denies */
        free_channel_list(&chptr->banlist);
        free_channel_list(&chptr->exceptlist);
        free_channel_list(&chptr->invexlist);

        /* Free the topic */
        free_topic(chptr);

        dlinkDelete(&chptr->node, &global_channel_list);
        del_from_channel_hash(chptr->chname, chptr);
        free_channel(chptr);
}

/* channel_pub_or_secret()
 *
 * input        - channel
 * output       - "=" if public, "@" if secret, else "*"
 * side effects -
 */
static const char *
channel_pub_or_secret(struct Channel *chptr)
{
        if(PubChannel(chptr))
                return ("=");
        else if(SecretChannel(chptr))
                return ("@");
        return ("*");
}

/* channel_member_names()
 *
 * input        - channel to list, client to list to, show endofnames
 * output       -
 * side effects - client is given list of users on channel
 */
void
channel_member_names(struct Channel *chptr, struct Client *client_p, int show_eon)
{
        struct membership *msptr;
        struct Client *target_p;
        dlink_node *ptr;
        char lbuf[BUFSIZE];
        char *t;
        int mlen;
        int tlen;
        int cur_len;
        int is_member;
        int stack = IsCapable(client_p, CLICAP_MULTI_PREFIX);

        if(ShowChannel(client_p, chptr))
        {
                is_member = IsMember(client_p, chptr);

                cur_len = mlen = ircsprintf(lbuf, form_str(RPL_NAMREPLY),
                                            me.name, client_p->name,
                                            channel_pub_or_secret(chptr), chptr->chname);

                t = lbuf + cur_len;

                DLINK_FOREACH(ptr, chptr->members.head)
                {
                        msptr = ptr->data;
                        target_p = msptr->client_p;

                        if(IsInvisible(target_p) && !is_member)
                                continue;

                        /* space, possible "@+" prefix */
                        if(cur_len + strlen(target_p->name) + 3 >= BUFSIZE - 3)
                        {
                                *(t - 1) = '\0';
                                sendto_one(client_p, "%s", lbuf);
                                cur_len = mlen;
                                t = lbuf + mlen;
                        }

                        tlen = ircsprintf(t, "%s%s ", find_channel_status(msptr, stack),
                                          target_p->name);

                        cur_len += tlen;
                        t += tlen;
                }

                /* The old behaviour here was to always output our buffer,
                 * even if there are no clients we can show.  This happens
                 * when a client does "NAMES" with no parameters, and all
                 * the clients on a -sp channel are +i.  I dont see a good
                 * reason for keeping that behaviour, as it just wastes
                 * bandwidth.  --anfl
                 */
                if(cur_len != mlen)
                {
                        *(t - 1) = '\0';
                        sendto_one(client_p, "%s", lbuf);
                }
        }

        if(show_eon)
                sendto_one(client_p, form_str(RPL_ENDOFNAMES),
                           me.name, client_p->name, chptr->chname);
}

/* del_invite()
 *
 * input        - channel to remove invite from, client to remove
 * output       -
 * side effects - user is removed from invite list, if exists
 */
void
del_invite(struct Channel *chptr, struct Client *who)
{
        dlinkFindDestroy(who, &chptr->invites);
        dlinkFindDestroy(chptr, &who->user->invited);
}

/* is_banned()
 *
 * input        - channel to check bans for, user to check bans against
 *                optional prebuilt buffers
 * output       - 1 if banned, else 0
 * side effects -
 */
int
is_banned(struct Channel *chptr, struct Client *who, struct membership *msptr,
          const char *s, const char *s2)
{
        char src_host[NICKLEN + USERLEN + HOSTLEN + 6];
        char src_iphost[NICKLEN + USERLEN + HOSTLEN + 6];
        char src_althost[NICKLEN + USERLEN + HOSTLEN + 6];
        char *s3 = NULL;
        dlink_node *ptr;
        struct Ban *actualBan = NULL;
        struct Ban *actualExcept = NULL;

        if(!MyClient(who))
                return 0;

        /* if the buffers havent been built, do it here */
        if(s == NULL)
        {
                ircsprintf(src_host, "%s!%s@%s", who->name, who->username, who->host);
                ircsprintf(src_iphost, "%s!%s@%s", who->name, who->username, who->sockhost);

                s = src_host;
                s2 = src_iphost;
        }
        if(who->localClient->mangledhost != NULL)
        {
                /* if host mangling mode enabled, also check their real host */
                if(!strcmp(who->host, who->localClient->mangledhost))
                {
                        ircsprintf(src_althost, "%s!%s@%s", who->name, who->username, who->orighost);
                        s3 = src_althost;
                }
                /* if host mangling mode not enabled and no other spoof,
                 * also check the mangled form of their host */
                else if (!IsDynSpoof(who))
                {
                        ircsprintf(src_althost, "%s!%s@%s", who->name, who->username, who->localClient->mangledhost);
                        s3 = src_althost;
                }
        }

        DLINK_FOREACH(ptr, chptr->banlist.head)
        {
                actualBan = ptr->data;
                if(match(actualBan->banstr, s) ||
                   match(actualBan->banstr, s2) ||
                   match_cidr(actualBan->banstr, s2) ||
                   match_extban(actualBan->banstr, who, chptr, CHFL_BAN) ||
                   (s3 != NULL && match(actualBan->banstr, s3)))
                        break;
                else
                        actualBan = NULL;
        }

        if((actualBan != NULL) && ConfigChannel.use_except)
        {
                DLINK_FOREACH(ptr, chptr->exceptlist.head)
                {
                        actualExcept = ptr->data;

                        /* theyre exempted.. */
                        if(match(actualExcept->banstr, s) ||
                           match(actualExcept->banstr, s2) ||
                           match_cidr(actualExcept->banstr, s2) ||
                           match_extban(actualExcept->banstr, who, chptr, CHFL_EXCEPTION) ||
                           (s3 != NULL && match(actualExcept->banstr, s3)))
                        {
                                /* cache the fact theyre not banned */
                                if(msptr != NULL)
                                {
                                        msptr->bants = chptr->bants;
                                        msptr->flags &= ~CHFL_BANNED;
                                }

                                return CHFL_EXCEPTION;
                        }
                }
        }

        /* cache the banned/not banned status */
        if(msptr != NULL)
        {
                msptr->bants = chptr->bants;

                if(actualBan != NULL)
                {
                        msptr->flags |= CHFL_BANNED;
                        return CHFL_BAN;
                }
                else
                {
                        msptr->flags &= ~CHFL_BANNED;
                        return 0;
                }
        }

        return ((actualBan ? CHFL_BAN : 0));
}

/* is_quieted()
 *
 * input        - channel to check bans for, user to check bans against
 *                optional prebuilt buffers
 * output       - 1 if banned, else 0
 * side effects -
 */
int
is_quieted(struct Channel *chptr, struct Client *who, struct membership *msptr,
           const char *s, const char *s2)
{
        char src_host[NICKLEN + USERLEN + HOSTLEN + 6];
        char src_iphost[NICKLEN + USERLEN + HOSTLEN + 6];
        char src_althost[NICKLEN + USERLEN + HOSTLEN + 6];
        char *s3 = NULL;
        dlink_node *ptr;
        struct Ban *actualBan = NULL;
        struct Ban *actualExcept = NULL;

        if(!MyClient(who))
                return 0;

        /* if the buffers havent been built, do it here */
        if(s == NULL)
        {
                ircsprintf(src_host, "%s!%s@%s", who->name, who->username, who->host);
                ircsprintf(src_iphost, "%s!%s@%s", who->name, who->username, who->sockhost);

                s = src_host;
                s2 = src_iphost;
        }
        if(who->localClient->mangledhost != NULL)
        {
                /* if host mangling mode enabled, also check their real host */
                if(!strcmp(who->host, who->localClient->mangledhost))
                {
                        ircsprintf(src_althost, "%s!%s@%s", who->name, who->username, who->orighost);
                        s3 = src_althost;
                }
                /* if host mangling mode not enabled and no other spoof,
                 * also check the mangled form of their host */
                else if (!IsDynSpoof(who))
                {
                        ircsprintf(src_althost, "%s!%s@%s", who->name, who->username, who->localClient->mangledhost);
                        s3 = src_althost;
                }
        }

        DLINK_FOREACH(ptr, chptr->quietlist.head)
        {
                actualBan = ptr->data;
                if(match(actualBan->banstr, s) ||
                   match(actualBan->banstr, s2) ||
                   match_cidr(actualBan->banstr, s2) ||
                   match_extban(actualBan->banstr, who, chptr, CHFL_QUIET) ||
                   (s3 != NULL && match(actualBan->banstr, s3)))
                        break;
                else
                        actualBan = NULL;
        }

        if((actualBan != NULL) && ConfigChannel.use_except)
        {
                DLINK_FOREACH(ptr, chptr->exceptlist.head)
                {
                        actualExcept = ptr->data;

                        /* theyre exempted.. */
                        if(match(actualExcept->banstr, s) ||
                           match(actualExcept->banstr, s2) ||
                           match_cidr(actualExcept->banstr, s2) ||
                           match_extban(actualExcept->banstr, who, chptr, CHFL_EXCEPTION) ||
                           (s3 != NULL && match(actualExcept->banstr, s3)))
                        {
                                /* cache the fact theyre not banned */
                                if(msptr != NULL)
                                {
                                        msptr->bants = chptr->bants;
                                        msptr->flags &= ~CHFL_BANNED;
                                }

                                return CHFL_EXCEPTION;
                        }
                }
        }

        /* cache the banned/not banned status */
        if(msptr != NULL)
        {
                msptr->bants = chptr->bants;

                if(actualBan != NULL)
                {
                        msptr->flags |= CHFL_BANNED;
                        return CHFL_BAN;
                }
                else
                {
                        msptr->flags &= ~CHFL_BANNED;
                        return 0;
                }
        }

        return ((actualBan ? CHFL_BAN : 0));
}

/* can_join()
 *
 * input        - client to check, channel to check for, key
 * output       - reason for not being able to join, else 0
 * side effects -
 */
int
can_join(struct Client *source_p, struct Channel *chptr, char *key)
{
        dlink_node *lp;
        dlink_node *ptr;
        struct Ban *invex = NULL;
        char src_host[NICKLEN + USERLEN + HOSTLEN + 6];
        char src_iphost[NICKLEN + USERLEN + HOSTLEN + 6];
        char src_althost[NICKLEN + USERLEN + HOSTLEN + 6];
        int use_althost = 0;
        hook_data_channel moduledata;

        s_assert(source_p->localClient != NULL);

        ircsprintf(src_host, "%s!%s@%s", source_p->name, source_p->username, source_p->host);
        ircsprintf(src_iphost, "%s!%s@%s", source_p->name, source_p->username, source_p->sockhost);
        if(source_p->localClient->mangledhost != NULL)
        {
                /* if host mangling mode enabled, also check their real host */
                if(!strcmp(source_p->host, source_p->localClient->mangledhost))
                {
                        ircsprintf(src_althost, "%s!%s@%s", source_p->name, source_p->username, source_p->orighost);
                        use_althost = 1;
                }
                /* if host mangling mode not enabled and no other spoof,
                 * also check the mangled form of their host */
                else if (!IsDynSpoof(source_p))
                {
                        ircsprintf(src_althost, "%s!%s@%s", source_p->name, source_p->username, source_p->localClient->mangledhost);
                        use_althost = 1;
                }
        }

        if((is_banned(chptr, source_p, NULL, src_host, src_iphost)) == CHFL_BAN)
                return (ERR_BANNEDFROMCHAN);

        if(chptr->mode.mode & MODE_INVITEONLY)
        {
                DLINK_FOREACH(lp, source_p->user->invited.head)
                {
                        if(lp->data == chptr)
                                break;
                }
                if(lp == NULL)
                {
                        if(!ConfigChannel.use_invex)
                                return (ERR_INVITEONLYCHAN);
                        DLINK_FOREACH(ptr, chptr->invexlist.head)
                        {
                                invex = ptr->data;
                                if(match(invex->banstr, src_host)
                                   || match(invex->banstr, src_iphost)
                                   || match_cidr(invex->banstr, src_iphost)
                                   || match_extban(invex->banstr, source_p, chptr, CHFL_INVEX)
                                   || (use_althost && match(invex->banstr, src_althost)))
                                        break;
                        }
                        if(ptr == NULL)
                                return (ERR_INVITEONLYCHAN);
                }
        }

        if(*chptr->mode.key && (EmptyString(key) || irccmp(chptr->mode.key, key)))
                return (ERR_BADCHANNELKEY);

        if(chptr->mode.limit &&
           dlink_list_length(&chptr->members) >= (unsigned long) chptr->mode.limit)
                return (ERR_CHANNELISFULL);

        if(chptr->mode.mode & MODE_REGONLY && EmptyString(source_p->user->suser))
                return ERR_NEEDREGGEDNICK;

        /* join throttling stuff --nenolod */
        if(chptr->mode.join_num > 0 && chptr->mode.join_time > 0)
        {
                if ((CurrentTime - chptr->join_delta <= 
                        chptr->mode.join_time) && (chptr->join_count >=
                        chptr->mode.join_num))
                        return ERR_THROTTLE;
        }

        moduledata.client = source_p;
        moduledata.chptr = chptr;
        moduledata.approved = 0;

        call_hook(h_can_join, &moduledata);

        return moduledata.approved;
}

/* can_send()
 *
 * input        - user to check in channel, membership pointer
 * output       - whether can explicitly send or not, else CAN_SEND_NONOP
 * side effects -
 */
int
can_send(struct Channel *chptr, struct Client *source_p, struct membership *msptr)
{
        if(IsServer(source_p) || IsService(source_p))
                return CAN_SEND_OPV;

        if(MyClient(source_p) && hash_find_resv(chptr->chname) &&
           !IsOper(source_p) && !IsExemptResv(source_p))
                return CAN_SEND_NO;

        if(msptr == NULL)
        {
                msptr = find_channel_membership(chptr, source_p);

                if(msptr == NULL)
                {
                        /* if its +m or +n and theyre not in the channel,
                         * they cant send.  we dont check bans here because
                         * theres no possibility of caching them --fl
                         */
                        if(chptr->mode.mode & MODE_NOPRIVMSGS || chptr->mode.mode & MODE_MODERATED)
                                return CAN_SEND_NO;
                        else
                                return CAN_SEND_NONOP;
                }
        }

        if(is_chanop_voiced(msptr))
                return CAN_SEND_OPV;

        if(chptr->mode.mode & MODE_MODERATED)
                return CAN_SEND_NO;

        if(MyClient(source_p))
        {
                /* cached can_send */
                if(msptr->bants == chptr->bants)
                {
                        if(can_send_banned(msptr))
                                return CAN_SEND_NO;
                }
                else if(is_banned(chptr, source_p, msptr, NULL, NULL) == CHFL_BAN
                        || is_quieted(chptr, source_p, msptr, NULL, NULL) == CHFL_BAN)
                        return CAN_SEND_NO;
        }

        return CAN_SEND_NONOP;
}

/* find_bannickchange_channel()
 * Input: client to check
 * Output: channel preventing nick change
 */
struct Channel *
find_bannickchange_channel(struct Client *client_p)
{
        struct Channel *chptr;
        struct membership *msptr;
        dlink_node *ptr;
        char src_host[NICKLEN + USERLEN + HOSTLEN + 6];
        char src_iphost[NICKLEN + USERLEN + HOSTLEN + 6];

        if (!MyClient(client_p))
                return NULL;

        ircsprintf(src_host, "%s!%s@%s", client_p->name, client_p->username, client_p->host);
        ircsprintf(src_iphost, "%s!%s@%s", client_p->name, client_p->username, client_p->sockhost);

        DLINK_FOREACH(ptr, client_p->user->channel.head)
        {
                msptr = ptr->data;
                chptr = msptr->chptr;
                if (is_chanop_voiced(msptr))
                        continue;
                /* cached can_send */
                if (msptr->bants == chptr->bants)
                {
                        if (can_send_banned(msptr))
                                return chptr;
                }
                else if (is_banned(chptr, client_p, msptr, src_host, src_iphost) == CHFL_BAN
                        || is_quieted(chptr, client_p, msptr, src_host, src_iphost) == CHFL_BAN)
                        return chptr;
        }
        return NULL;
}

/* void check_spambot_warning(struct Client *source_p)
 * Input: Client to check, channel name or NULL if this is a part.
 * Output: none
 * Side-effects: Updates the client's oper_warn_count_down, warns the
 *    IRC operators if necessary, and updates join_leave_countdown as
 *    needed.
 */
void
check_spambot_warning(struct Client *source_p, const char *name)
{
        int t_delta;
        int decrement_count;
        if((GlobalSetOptions.spam_num &&
            (source_p->localClient->join_leave_count >= GlobalSetOptions.spam_num)))
        {
                if(source_p->localClient->oper_warn_count_down > 0)
                        source_p->localClient->oper_warn_count_down--;
                else
                        source_p->localClient->oper_warn_count_down = 0;
                if(source_p->localClient->oper_warn_count_down == 0)
                {
                        /* Its already known as a possible spambot */
                        if(name != NULL)
                                sendto_realops_snomask(SNO_BOTS, L_ALL,
                                                     "User %s (%s@%s) trying to join %s is a possible spambot",
                                                     source_p->name,
                                                     source_p->username, source_p->orighost, name);
                        else
                                sendto_realops_snomask(SNO_BOTS, L_ALL,
                                                     "User %s (%s@%s) is a possible spambot",
                                                     source_p->name,
                                                     source_p->username, source_p->orighost);
                        source_p->localClient->oper_warn_count_down = OPER_SPAM_COUNTDOWN;
                }
        }
        else
        {
                if((t_delta =
                    (CurrentTime - source_p->localClient->last_leave_time)) >
                   JOIN_LEAVE_COUNT_EXPIRE_TIME)
                {
                        decrement_count = (t_delta / JOIN_LEAVE_COUNT_EXPIRE_TIME);
                        if(decrement_count > source_p->localClient->join_leave_count)
                                source_p->localClient->join_leave_count = 0;
                        else
                                source_p->localClient->join_leave_count -= decrement_count;
                }
                else
                {
                        if((CurrentTime -
                            (source_p->localClient->last_join_time)) < GlobalSetOptions.spam_time)
                        {
                                /* oh, its a possible spambot */
                                source_p->localClient->join_leave_count++;
                        }
                }
                if(name != NULL)
                        source_p->localClient->last_join_time = CurrentTime;
                else
                        source_p->localClient->last_leave_time = CurrentTime;
        }
}

/* check_splitmode()
 *
 * input        -
 * output       -
 * side effects - compares usercount and servercount against their split
 *                values and adjusts splitmode accordingly
 */
void
check_splitmode(void *unused)
{
        if(splitchecking && (ConfigChannel.no_join_on_split || ConfigChannel.no_create_on_split))
        {
                /* not split, we're being asked to check now because someone
                 * has left
                 */
                if(!splitmode)
                {
                        if(eob_count < split_servers || Count.total < split_users)
                        {
                                splitmode = 1;
                                sendto_realops_snomask(SNO_GENERAL, L_ALL,
                                                     "Network split, activating splitmode");
                                eventAddIsh("check_splitmode", check_splitmode, NULL, 2);
                        }
                }
                /* in splitmode, check whether its finished */
                else if(eob_count >= split_servers && Count.total >= split_users)
                {
                        splitmode = 0;

                        sendto_realops_snomask(SNO_GENERAL, L_ALL,
                                             "Network rejoined, deactivating splitmode");

                        eventDelete(check_splitmode, NULL);
                }
        }
}


/* allocate_topic()
 *
 * input        - channel to allocate topic for
 * output       - 1 on success, else 0
 * side effects - channel gets a topic allocated
 */
static void
allocate_topic(struct Channel *chptr)
{
        void *ptr;

        if(chptr == NULL)
                return;

        ptr = BlockHeapAlloc(topic_heap);

        /* Basically we allocate one large block for the topic and
         * the topic info.  We then split it up into two and shove it
         * in the chptr 
         */
        chptr->topic = ptr;
        chptr->topic_info = (char *) ptr + TOPICLEN + 1;
        *chptr->topic = '\0';
        *chptr->topic_info = '\0';
}

/* free_topic()
 *
 * input        - channel which has topic to free
 * output       -
 * side effects - channels topic is free'd
 */
static void
free_topic(struct Channel *chptr)
{
        void *ptr;

        if(chptr == NULL || chptr->topic == NULL)
                return;

        /* This is safe for now - If you change allocate_topic you
         * MUST change this as well
         */
        ptr = chptr->topic;
        BlockHeapFree(topic_heap, ptr);
        chptr->topic = NULL;
        chptr->topic_info = NULL;
}

/* set_channel_topic()
 *
 * input        - channel, topic to set, topic info and topic ts
 * output       -
 * side effects - channels topic, topic info and TS are set.
 */
void
set_channel_topic(struct Channel *chptr, const char *topic, const char *topic_info, time_t topicts)
{
        if(strlen(topic) > 0)
        {
                if(chptr->topic == NULL)
                        allocate_topic(chptr);
                strlcpy(chptr->topic, topic, TOPICLEN + 1);
                strlcpy(chptr->topic_info, topic_info, USERHOST_REPLYLEN);
                chptr->topic_time = topicts;
        }
        else
        {
                if(chptr->topic != NULL)
                        free_topic(chptr);
                chptr->topic_time = 0;
        }
}

static const struct mode_letter
{
        const unsigned int mode;
        const unsigned char letter;
} flags[] =
{
        {MODE_INVITEONLY, 'i'},
        {MODE_MODERATED, 'm'},
        {MODE_NOPRIVMSGS, 'n'},
        {MODE_PRIVATE, 'p'},
        {MODE_SECRET, 's'},
        {MODE_TOPICLIMIT, 't'},
        {MODE_NOCOLOR, 'c'},
        {MODE_FREEINVITE, 'g'},
        {MODE_OPMODERATE, 'z'},
        {MODE_EXLIMIT, 'L'},
        {MODE_PERMANENT, 'P'},
        {MODE_FREETARGET, 'F'},
        {MODE_DISFORWARD, 'Q'},
        {MODE_REGONLY, 'r'},
        {0, '\0'}
};

/* channel_modes()
 *
 * inputs       - pointer to channel
 *              - pointer to client
 * output       - NONE
 * side effects - write the "simple" list of channel modes for channel
 * chptr onto buffer mbuf with the parameters in pbuf.
 *
 * Stolen from ShadowIRCd 4 --nenolod
 */
const char *
channel_modes(struct Channel *chptr, struct Client *client_p)
{
        int i;
        char buf1[BUFSIZE];
        char buf2[BUFSIZE];
        static char final[BUFSIZE];
        char *mbuf = buf1;
        char *pbuf = buf2;

        *mbuf++ = '+';
        *pbuf = '\0';

        for (i = 0; flags[i].mode; ++i)
                if(chptr->mode.mode & flags[i].mode)
                        *mbuf++ = flags[i].letter;

        if(chptr->mode.limit)
        {
                *mbuf++ = 'l';

                if(IsMember(client_p, chptr) || IsServer(client_p) || IsMe(client_p))
                        pbuf += ircsprintf(pbuf, "%d ", chptr->mode.limit);
        }

        if(*chptr->mode.key)
        {
                *mbuf++ = 'k';

                if(*pbuf || IsMember(client_p, chptr) || IsServer(client_p) || IsMe(client_p))
                        pbuf += ircsprintf(pbuf, "%s ", chptr->mode.key);
        }

        if(chptr->mode.join_num)
        {
                *mbuf++ = 'j';

                if(*pbuf || IsMember(client_p, chptr) || IsServer(client_p) || IsMe(client_p))
                        pbuf += ircsprintf(pbuf, "%d:%d ", chptr->mode.join_num,
                                           chptr->mode.join_time);
        }

        if(*chptr->mode.forward && (ConfigChannel.use_forward || IsServer(client_p) || IsMe(client_p)))
        {
                *mbuf++ = 'f';

                if(*pbuf || IsMember(client_p, chptr) || IsServer(client_p) || IsMe(client_p))
                        pbuf += ircsprintf(pbuf, "%s ", chptr->mode.forward);
        }

        *mbuf = '\0';

        ircsprintf(final, "%s %s", buf1, buf2);
        return final;
}

/* Now lets do some stuff to keep track of what combinations of
 * servers exist...
 * Note that the number of combinations doubles each time you add
 * something to this list. Each one is only quick if no servers use that
 * combination, but if the numbers get too high here MODE will get too
 * slow. I suggest if you get more than 7 here, you consider getting rid
 * of some and merging or something. If it wasn't for irc+cs we would
 * probably not even need to bother about most of these, but unfortunately
 * we do. -A1kmm
 */

/* void init_chcap_usage_counts(void)
 *
 * Inputs       - none
 * Output       - none
 * Side-effects - Initialises the usage counts to zero. Fills in the
 *                chcap_yes and chcap_no combination tables.
 */
void
init_chcap_usage_counts(void)
{
        unsigned long m, c, y, n;

        memset(chcap_combos, 0, sizeof(chcap_combos));

        /* For every possible combination */
        for (m = 0; m < NCHCAP_COMBOS; m++)
        {
                /* Check each capab */
                for (c = y = n = 0; c < NCHCAPS; c++)
                {
                        if((m & (1 << c)) == 0)
                                n |= channel_capabs[c];
                        else
                                y |= channel_capabs[c];
                }
                chcap_combos[m].cap_yes = y;
                chcap_combos[m].cap_no = n;
        }
}

/* void set_chcap_usage_counts(struct Client *serv_p)
 * Input: serv_p; The client whose capabs to register.
 * Output: none
 * Side-effects: Increments the usage counts for the correct capab
 *               combination.
 */
void
set_chcap_usage_counts(struct Client *serv_p)
{
        int n;

        for (n = 0; n < NCHCAP_COMBOS; n++)
        {
                if(IsCapable(serv_p, chcap_combos[n].cap_yes) &&
                   NotCapable(serv_p, chcap_combos[n].cap_no))
                {
                        chcap_combos[n].count++;
                        return;
                }
        }

        /* This should be impossible -A1kmm. */
        s_assert(0);
}

/* void set_chcap_usage_counts(struct Client *serv_p)
 *
 * Inputs       - serv_p; The client whose capabs to register.
 * Output       - none
 * Side-effects - Decrements the usage counts for the correct capab
 *                combination.
 */
void
unset_chcap_usage_counts(struct Client *serv_p)
{
        int n;

        for (n = 0; n < NCHCAP_COMBOS; n++)
        {
                if(IsCapable(serv_p, chcap_combos[n].cap_yes) &&
                   NotCapable(serv_p, chcap_combos[n].cap_no))
                {
                        /* Hopefully capabs can't change dynamically or anything... */
                        s_assert(chcap_combos[n].count > 0);

                        if(chcap_combos[n].count > 0)
                                chcap_combos[n].count--;
                        return;
                }
        }

        /* This should be impossible -A1kmm. */
        s_assert(0);
}

/* void send_cap_mode_changes(struct Client *client_p,
 *                        struct Client *source_p,
 *                        struct Channel *chptr, int cap, int nocap)
 * Input: The client sending(client_p), the source client(source_p),
 *        the channel to send mode changes for(chptr)
 * Output: None.
 * Side-effects: Sends the appropriate mode changes to capable servers.
 *
 * Reverted back to my original design, except that we now keep a count
 * of the number of servers which each combination as an optimisation, so
 * the capabs combinations which are not needed are not worked out. -A1kmm
 */
void
send_cap_mode_changes(struct Client *client_p, struct Client *source_p,
                      struct Channel *chptr, struct ChModeChange mode_changes[], int mode_count)
{
        static char modebuf[BUFSIZE];
        static char parabuf[BUFSIZE];
        int i, mbl, pbl, nc, mc, preflen, len;
        char *pbuf;
        const char *arg;
        int dir;
        int j;
        int cap;
        int nocap;
        int arglen;

        /* Now send to servers... */
        for (j = 0; j < NCHCAP_COMBOS; j++)
        {
                if(chcap_combos[j].count == 0)
                        continue;

                mc = 0;
                nc = 0;
                pbl = 0;
                parabuf[0] = 0;
                pbuf = parabuf;
                dir = MODE_QUERY;

                cap = chcap_combos[j].cap_yes;
                nocap = chcap_combos[j].cap_no;

                if(cap & CAP_TS6)
                        mbl = preflen = ircsprintf(modebuf, ":%s TMODE %ld %s ",
                                                   use_id(source_p), (long) chptr->channelts,
                                                   chptr->chname);
                else
                        mbl = preflen = ircsprintf(modebuf, ":%s MODE %s ",
                                                   source_p->name, chptr->chname);

                /* loop the list of - modes we have */
                for (i = 0; i < mode_count; i++)
                {
                        /* if they dont support the cap we need, or they do support a cap they
                         * cant have, then dont add it to the modebuf.. that way they wont see
                         * the mode
                         */
                        if((mode_changes[i].letter == 0) ||
                           ((cap & mode_changes[i].caps) != mode_changes[i].caps)
                           || ((nocap & mode_changes[i].nocaps) != mode_changes[i].nocaps))
                                continue;

                        if((cap & CAP_TS6) && !EmptyString(mode_changes[i].id))
                                arg = mode_changes[i].id;
                        else
                                arg = mode_changes[i].arg;

                        if(arg)
                        {
                                arglen = strlen(arg);

                                /* dont even think about it! --fl */
                                if(arglen > MODEBUFLEN - 5)
                                        continue;
                        }

                        /* if we're creeping past the buf size, we need to send it and make
                         * another line for the other modes
                         * XXX - this could give away server topology with uids being
                         * different lengths, but not much we can do, except possibly break
                         * them as if they were the longest of the nick or uid at all times,
                         * which even then won't work as we don't always know the uid -A1kmm.
                         */
                        if(arg && ((mc == MAXMODEPARAMSSERV) ||
                                   ((mbl + pbl + arglen + 4) > (BUFSIZE - 3))))
                        {
                                if(nc != 0)
                                        sendto_server(client_p, chptr, cap, nocap,
                                                      "%s %s", modebuf, parabuf);
                                nc = 0;
                                mc = 0;

                                mbl = preflen;
                                pbl = 0;
                                pbuf = parabuf;
                                parabuf[0] = 0;
                                dir = MODE_QUERY;
                        }

                        if(dir != mode_changes[i].dir)
                        {
                                modebuf[mbl++] = (mode_changes[i].dir == MODE_ADD) ? '+' : '-';
                                dir = mode_changes[i].dir;
                        }

                        modebuf[mbl++] = mode_changes[i].letter;
                        modebuf[mbl] = 0;
                        nc++;

                        if(arg != NULL)
                        {
                                len = ircsprintf(pbuf, "%s ", arg);
                                pbuf += len;
                                pbl += len;
                                mc++;
                        }
                }

                if(pbl && parabuf[pbl - 1] == ' ')
                        parabuf[pbl - 1] = 0;

                if(nc != 0)
                        sendto_server(client_p, chptr, cap, nocap, "%s %s", modebuf, parabuf);
        }
}