Initial import

[ratbox-ambernet.git] / modules / core / m_nick.c

/*
 *  ircd-ratbox: A slightly useful ircd.
 *  m_nick.c: Sets a users nick.
 *
 *  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: m_nick.c 23853 2007-04-22 14:09:34Z jilles $
 */

#include "stdinc.h"
#include "client.h"
#include "hash.h"
#include "irc_string.h"
#include "ircd.h"
#include "numeric.h"
#include "s_conf.h"
#include "s_stats.h"
#include "s_user.h"
#include "hash.h"
#include "whowas.h"
#include "s_serv.h"
#include "send.h"
#include "channel.h"
#include "s_log.h"
#include "msg.h"
#include "parse.h"
#include "modules.h"
#include "common.h"
#include "packet.h"
#include "scache.h"
#include "s_newconf.h"
#include "monitor.h"

/* Give all UID nicks the same TS. This ensures nick TS is always the same on
 * all servers for each nick-user pair, also if a user with a UID nick changes
 * their nick but is collided again (the server detecting the collision will
 * not propagate the nick change further). -- jilles
 */
#define SAVE_NICKTS 100

static int mr_nick(struct Client *, struct Client *, int, const char **);
static int m_nick(struct Client *, struct Client *, int, const char **);
static int mc_nick(struct Client *, struct Client *, int, const char **);
static int ms_nick(struct Client *, struct Client *, int, const char **);
static int ms_uid(struct Client *, struct Client *, int, const char **);
static int ms_save(struct Client *, struct Client *, int, const char **);
static void save_user(struct Client *, struct Client *, struct Client *);

struct Message nick_msgtab = {
        "NICK", 0, 0, 0, MFLG_SLOW,
        {{mr_nick, 0}, {m_nick, 0}, {mc_nick, 3}, {ms_nick, 8}, mg_ignore, {m_nick, 0}}
};
struct Message uid_msgtab = {
        "UID", 0, 0, 0, MFLG_SLOW,
        {mg_ignore, mg_ignore, mg_ignore, {ms_uid, 9}, mg_ignore, mg_ignore}
};
struct Message save_msgtab = {
        "SAVE", 0, 0, 0, MFLG_SLOW,
        {mg_ignore, mg_ignore, mg_ignore, {ms_save, 3}, mg_ignore, mg_ignore}
};

mapi_clist_av1 nick_clist[] = { &nick_msgtab, &uid_msgtab, &save_msgtab, NULL };
DECLARE_MODULE_AV1(nick, NULL, NULL, nick_clist, NULL, NULL, "$Revision: 23853 $");

static int change_remote_nick(struct Client *, struct Client *, time_t, const char *, int);

static int clean_nick(const char *, int loc_client);
static int clean_username(const char *);
static int clean_host(const char *);
static int clean_uid(const char *uid);

static void set_initial_nick(struct Client *client_p, struct Client *source_p, char *nick);
static void change_local_nick(struct Client *client_p, struct Client *source_p, char *nick, int);
static int register_client(struct Client *client_p, struct Client *server, 
                           const char *nick, time_t newts, int parc, const char *parv[]);

static int perform_nick_collides(struct Client *, struct Client *,
                                 struct Client *, int, const char **, 
                                 time_t, const char *, const char *);
static int perform_nickchange_collides(struct Client *, struct Client *,
                                       struct Client *, int, const char **, 
                                       time_t, const char *);

/* mr_nick()
 *       parv[0] = sender prefix
 *       parv[1] = nickname
 */
static int
mr_nick(struct Client *client_p, struct Client *source_p, int parc, const char *parv[])
{
        struct Client *target_p;
        char nick[NICKLEN];
        char *s;

        if(parc < 2 || EmptyString(parv[1]) || (parv[1][0] == '~'))
        {
                sendto_one(source_p, form_str(ERR_NONICKNAMEGIVEN),
                           me.name, 
                           EmptyString(source_p->name) ? "*" : source_p->name);
                return 0;
        }

        /* due to the scandinavian origins, (~ being uppercase of ^) and ~
         * being disallowed as a nick char, we need to chop the first ~
         * instead of just erroring.
         */
        if((s = strchr(parv[1], '~')))
                *s = '\0';

        /* copy the nick and terminate it */
        strlcpy(nick, parv[1], sizeof(nick));

        /* check the nickname is ok */
        if(!clean_nick(nick, 1))
        {
                sendto_one(source_p, form_str(ERR_ERRONEUSNICKNAME),
                           me.name, EmptyString(parv[0]) ? "*" : parv[0], parv[1]);
                return 0;
        }

        /* check if the nick is resv'd */
        if(find_nick_resv(nick))
        {
                sendto_one(source_p, form_str(ERR_ERRONEUSNICKNAME),
                           me.name, EmptyString(source_p->name) ? "*" : source_p->name, nick);
                return 0;
        }

        if(hash_find_nd(nick))
        {
                sendto_one(source_p, form_str(ERR_UNAVAILRESOURCE),
                        me.name, 
                        EmptyString(source_p->name) ? "*" : source_p->name,
                        nick);
                return 0;
        }

        if((target_p = find_client(nick)) == NULL)
                set_initial_nick(client_p, source_p, nick);
        else if(source_p == target_p)
                strcpy(source_p->user->nick, nick);
        else
                sendto_one(source_p, form_str(ERR_NICKNAMEINUSE), me.name, "*", nick);

        return 0;
}

/* m_nick()
 *     parv[0] = sender prefix
 *     parv[1] = nickname
 */
static int
m_nick(struct Client *client_p, struct Client *source_p, int parc, const char *parv[])
{
        struct Client *target_p;
        char nick[NICKLEN];
        char *s;

        if(parc < 2 || EmptyString(parv[1]) || (parv[1][0] == '~'))
        {
                sendto_one(source_p, form_str(ERR_NONICKNAMEGIVEN),
                           me.name, source_p->name);
                return 0;
        }

        /* due to the scandinavian origins, (~ being uppercase of ^) and ~
         * being disallowed as a nick char, we need to chop the first ~
         * instead of just erroring.
         */
        if((s = strchr(parv[1], '~')))
                *s = '\0';

        /* mark end of grace period, to prevent nickflooding */
        if(!IsFloodDone(source_p))
                flood_endgrace(source_p);

        /* terminate nick to NICKLEN, we dont want clean_nick() to error! */
        strlcpy(nick, parv[1], sizeof(nick));

        /* check the nickname is ok */
        if(!clean_nick(nick, 1))
        {
                sendto_one(source_p, form_str(ERR_ERRONEUSNICKNAME),
                           me.name, parv[0], nick);
                return 0;
        }

        if(!IsExemptResv(source_p) && find_nick_resv(nick))
        {
                sendto_one(source_p, form_str(ERR_ERRONEUSNICKNAME),
                           me.name, source_p->name, nick);
                return 0;
        }

        if(hash_find_nd(nick))
        {
                sendto_one(source_p, form_str(ERR_UNAVAILRESOURCE),
                        me.name, 
                        EmptyString(source_p->name) ? "*" : source_p->name,
                        nick);
                return 0;
        }

        if((target_p = find_client(nick)))
        {
                /* If(target_p == source_p) the client is changing nicks between
                 * equivalent nicknames ie: [nick] -> {nick}
                 */
                if(target_p == source_p)
                {
                        /* check the nick isnt exactly the same */
                        if(strcmp(target_p->name, nick))
                                change_local_nick(client_p, source_p, nick, 1);

                }

                /* drop unregged client */
                else if(IsUnknown(target_p))
                {
                        exit_client(NULL, target_p, &me, "Overridden");
                        change_local_nick(client_p, source_p, nick, 1);
                }
                else
                        sendto_one(source_p, form_str(ERR_NICKNAMEINUSE), me.name, parv[0], nick);

                return 0;
        }
        else
                change_local_nick(client_p, source_p, nick, 1);

        return 0;
}

/* ms_nick()
 *      
 * server -> server nick change
 *    parv[0] = sender prefix
 *    parv[1] = nickname
 *    parv[2] = TS when nick change
 *
 * server introducing new nick
 *    parv[0] = sender prefix
 *    parv[1] = nickname
 *    parv[2] = hop count
 *    parv[3] = TS
 *    parv[4] = umode
 *    parv[5] = username
 *    parv[6] = hostname
 *    parv[7] = server
 *    parv[8] = ircname
 */
static int
mc_nick(struct Client *client_p, struct Client *source_p, int parc, const char *parv[])
{
        struct Client *target_p;
        time_t newts = 0;

        /* if nicks erroneous, or too long, kill */
        if(!clean_nick(parv[1], 0))
        {
                ServerStats->is_kill++;
                sendto_realops_flags(UMODE_DEBUG, L_ALL,
                                     "Bad Nick: %s From: %s(via %s)",
                                     parv[1], source_p->servptr->name,
                                     client_p->name);
                sendto_one(client_p, ":%s KILL %s :%s (Bad Nickname)",
                           me.name, parv[1], me.name);

                /* bad nick change, issue kill for the old nick to the rest
                 * of the network.
                 */
                kill_client_serv_butone(client_p, source_p,
                                        "%s (Bad Nickname)", me.name);
                source_p->flags |= FLAGS_KILLED;
                exit_client(client_p, source_p, &me, "Bad Nickname");
                return 0;
        }
                              
        newts = atol(parv[2]);
        target_p = find_client(parv[1]);

        /* if the nick doesnt exist, allow it and process like normal */
        if(target_p == NULL)
        {
                change_remote_nick(client_p, source_p, newts, parv[1], 1);
        }
        else if(IsUnknown(target_p))
        {
                exit_client(NULL, target_p, &me, "Overridden");
                change_remote_nick(client_p, source_p, newts, parv[1], 1);
        }
        else if(target_p == source_p)
        {
                /* client changing case of nick */
                if(strcmp(target_p->name, parv[1]))
                        change_remote_nick(client_p, source_p, newts, parv[1], 1);
        }
        /* we've got a collision! */
        else
                perform_nickchange_collides(source_p, client_p, target_p, 
                                            parc, parv, newts, parv[1]);

        return 0;
}

static int
ms_nick(struct Client *client_p, struct Client *source_p, int parc, const char *parv[])
{
        struct Client *target_p;
        time_t newts = 0;

        if(parc != 9)
        {
                sendto_realops_flags(UMODE_ALL, L_ALL,
                                "Dropping server %s due to (invalid) command 'NICK' "
                                "with %d arguments (expecting 9)",
                                client_p->name, parc);
                ilog(L_SERVER, "Excess parameters (%d) for command 'NICK' from %s.",
                        parc, client_p->name);
                exit_client(client_p, client_p, client_p,
                                "Excess parameters to NICK command");
                return 0;
        }

        /* if nicks empty, erroneous, or too long, kill */
        if(!clean_nick(parv[1], 0))
        {
                ServerStats->is_kill++;
                sendto_realops_flags(UMODE_DEBUG, L_ALL,
                                     "Bad Nick: %s From: %s(via %s)",
                                     parv[1], parv[7], client_p->name);
                sendto_one(client_p, ":%s KILL %s :%s (Bad Nickname)",
                           me.name, parv[1], me.name);
                return 0;
        }
                              
        /* invalid username or host? */
        if(!clean_username(parv[5]) || !clean_host(parv[6]))
        {
                ServerStats->is_kill++;
                sendto_realops_flags(UMODE_DEBUG, L_ALL,
                                "Bad user@host: %s@%s From: %s(via %s)",
                                parv[5], parv[6], parv[7],
                                client_p->name);
                sendto_one(client_p, ":%s KILL %s :%s (Bad user@host)",
                                me.name, parv[1], me.name);
                return 0;
        }

        /* check the length of the clients gecos */
        if(strlen(parv[8]) > REALLEN)
        {
                char *s = LOCAL_COPY(parv[8]);
                /* why exactly do we care? --fl */
                sendto_realops_flags(UMODE_ALL, L_ALL,
                                "Long realname from server %s for %s", parv[7],
                                parv[1]);

                s[REALLEN] = '\0';
                parv[8] = s;
        }

        newts = atol(parv[3]);

        target_p = find_client(parv[1]);

        /* if the nick doesnt exist, allow it and process like normal */
        if(target_p == NULL)
        {
                register_client(client_p, NULL, parv[1], newts, parc, parv);
        }
        else if(IsUnknown(target_p))
        {
                exit_client(NULL, target_p, &me, "Overridden");
                register_client(client_p, NULL, parv[1], newts, parc, parv);
        }
        else if(target_p == source_p)
        {
                /* client changing case of nick */
                if(strcmp(target_p->name, parv[1]))
                        register_client(client_p, NULL, parv[1], newts, parc, parv);
        }
        /* we've got a collision! */
        else
                perform_nick_collides(source_p, client_p, target_p, parc, parv, 
                                        newts, parv[1], NULL);

        return 0;
}

/* ms_uid()
 *     parv[1] - nickname
 *     parv[2] - hops
 *     parv[3] - TS
 *     parv[4] - umodes
 *     parv[5] - username
 *     parv[6] - hostname
 *     parv[7] - IP
 *     parv[8] - UID
 *     parv[9] - gecos
 */
static int
ms_uid(struct Client *client_p, struct Client *source_p, int parc, const char *parv[])
{
        struct Client *target_p;
        time_t newts = 0;

        newts = atol(parv[3]);

        if(parc != 10)
        {
                sendto_realops_flags(UMODE_ALL, L_ALL,
                                "Dropping server %s due to (invalid) command 'UID' "
                                "with %d arguments (expecting 10)",
                                client_p->name, parc);
                ilog(L_SERVER, "Excess parameters (%d) for command 'UID' from %s.",
                        parc, client_p->name);
                exit_client(client_p, client_p, client_p,
                                "Excess parameters to UID command");
                return 0;
        }

        /* if nicks erroneous, or too long, kill */
        if(!clean_nick(parv[1], 0))
        {
                ServerStats->is_kill++;
                sendto_realops_flags(UMODE_DEBUG, L_ALL,
                                     "Bad Nick: %s From: %s(via %s)",
                                     parv[1], source_p->name,
                                     client_p->name);
                sendto_one(client_p, ":%s KILL %s :%s (Bad Nickname)",
                           me.id, parv[8], me.name);
                return 0;
        }

        if(!clean_username(parv[5]) || !clean_host(parv[6]))
        {
                ServerStats->is_kill++;
                sendto_realops_flags(UMODE_DEBUG, L_ALL,
                                     "Bad user@host: %s@%s From: %s(via %s)",
                                     parv[5], parv[6], source_p->name,
                                     client_p->name);
                sendto_one(client_p, ":%s KILL %s :%s (Bad user@host)",
                           me.id, parv[8], me.name);
                return 0;
        }

        if(!clean_uid(parv[8]))
        {
                ServerStats->is_kill++;
                sendto_realops_flags(UMODE_DEBUG, L_ALL,
                                        "Bad UID: %s From: %s(via %s)",
                                        parv[8], source_p->name,
                                        client_p->name);
                sendto_one(client_p, ":%s KILL %s :%s (Bad UID)",
                                me.id, parv[8], me.name);
                return 0;
        }

        /* check length of clients gecos */
        if(strlen(parv[9]) > REALLEN)
        {
                char *s = LOCAL_COPY(parv[9]);
                sendto_realops_flags(UMODE_ALL, L_ALL, "Long realname from server %s for %s",
                                     parv[0], parv[1]);
                s[REALLEN] = '\0';
                parv[9] = s;
        }

        target_p = find_client(parv[1]);
        
        if(target_p == NULL)
        {
                register_client(client_p, source_p, parv[1], newts, parc, parv);
        }
        else if(IsUnknown(target_p))
        {
                exit_client(NULL, target_p, &me, "Overridden");
                register_client(client_p, source_p, parv[1], newts, parc, parv);
        }
        /* we've got a collision! */
        else
                perform_nick_collides(source_p, client_p, target_p, parc, parv,
                                        newts, parv[1], parv[8]);

        return 0;
}

/* ms_save()
 *   parv[1] - UID
 *   parv[2] - TS
 */
static int
ms_save(struct Client *client_p, struct Client *source_p, int parc, const char *parv[])
{
        struct Client *target_p;

        target_p = find_id(parv[1]);
        if (target_p == NULL)
                return 0;
        if (!IsPerson(target_p))
                sendto_realops_flags(UMODE_ALL, L_ALL,
                                "Ignored SAVE message for non-person %s from %s",
                                target_p->name, source_p->name);
        else if (IsDigit(target_p->name[0]))
                sendto_realops_flags(UMODE_DEBUG, L_ALL,
                                "Ignored noop SAVE message for %s from %s",
                                target_p->name, source_p->name);
        else if (target_p->tsinfo == atol(parv[2]))
                save_user(client_p, source_p, target_p);
        else
                sendto_realops_flags(UMODE_SKILL, L_ALL,
                                "Ignored SAVE message for %s from %s",
                                target_p->name, source_p->name);
        return 0;
}

/* clean_nick()
 *
 * input        - nickname to check
 * output       - 0 if erroneous, else 1
 * side effects - 
 */
static int
clean_nick(const char *nick, int loc_client)
{
        int len = 0;

        /* nicks cant start with a digit or -, and must have a length */
        if(*nick == '-' || *nick == '\0')
                return 0;

        if(loc_client && IsDigit(*nick))
                return 0;

        for (; *nick; nick++)
        {
                len++;
                if(!IsNickChar(*nick))
                        return 0;
        }

        /* nicklen is +1 */
        if(len >= NICKLEN)
                return 0;

        return 1;
}

/* clean_username()
 *
 * input        - username to check
 * output       - 0 if erroneous, else 0
 * side effects -
 */
static int
clean_username(const char *username)
{
        int len = 0;

        for (; *username; username++)
        {
                len++;

                if(!IsUserChar(*username))
                        return 0;
        }

        if(len > USERLEN)
                return 0;

        return 1;
}

/* clean_host()
 *
 * input        - host to check
 * output       - 0 if erroneous, else 0
 * side effects -
 */
static int
clean_host(const char *host)
{
        int len = 0;

        for (; *host; host++)
        {
                len++;

                if(!IsHostChar(*host))
                        return 0;
        }

        if(len > HOSTLEN)
                return 0;

        return 1;
}

static int
clean_uid(const char *uid)
{
        int len = 1;

        if(!IsDigit(*uid++))
                return 0;

        for(; *uid; uid++)
        {
                len++;

                if(!IsIdChar(*uid))
                        return 0;
        }

        if(len != IDLEN-1)
                return 0;

        return 1;
}

static void
set_initial_nick(struct Client *client_p, struct Client *source_p, char *nick)
{
        char buf[USERLEN + 1];

        /* This had to be copied here to avoid problems.. */
        source_p->tsinfo = CurrentTime;
        if(!EmptyString(source_p->name))
                del_from_client_hash(source_p->name, source_p);
        else
        {
                make_user(source_p);
                source_p->name = source_p->user->nick;
        }

        strcpy(source_p->user->nick, nick);
        add_to_client_hash(nick, source_p);

        /* fd_desc is long enough */
        comm_note(client_p->localClient->fd, "Nick: %s", nick);

        if(HasSentUser(source_p))
        {
                strlcpy(buf, source_p->username, sizeof(buf));

                /* got user, heres nick. */
                register_local_user(client_p, source_p, buf);

        }
}

static void
change_local_nick(struct Client *client_p, struct Client *source_p, char *nick,
                int dosend)
{
        struct Client *target_p;
        dlink_node *ptr, *next_ptr;
        int samenick;

        if (dosend)
        {
                if((source_p->localClient->last_nick_change + ConfigFileEntry.max_nick_time) < CurrentTime)
                        source_p->localClient->number_of_nick_changes = 0;

                if(ConfigFileEntry.anti_nick_flood && !IsOper(source_p) &&
                                source_p->localClient->number_of_nick_changes > ConfigFileEntry.max_nick_changes)
                {
                        sendto_one(source_p, form_str(ERR_NICKTOOFAST), 
                                        me.name, source_p->name, source_p->name, 
                                        nick, ConfigFileEntry.max_nick_time);
                        return;
                }

                source_p->localClient->last_nick_change = CurrentTime;
                source_p->localClient->number_of_nick_changes++;
        }

        samenick = irccmp(source_p->name, nick) ? 0 : 1;

        /* dont reset TS if theyre just changing case of nick */
        if(!samenick)
        {
                /* force the TS to increase -- jilles */
                if (source_p->tsinfo >= CurrentTime)
                        source_p->tsinfo++;
                else
                        source_p->tsinfo = CurrentTime;
                monitor_signoff(source_p);
                /* we only do bancache for local users -- jilles */
                if (source_p->user)
                        invalidate_bancache_user(source_p);
        }

        sendto_realops_flags(UMODE_NCHANGE, L_ALL,
                        "Nick change: From %s to %s [%s@%s]",
                        source_p->name, nick, source_p->username, source_p->host);

        /* send the nick change to the users channels */
        sendto_common_channels_local(source_p, ":%s!%s@%s NICK :%s",
                                source_p->name, source_p->username, 
                                source_p->host, nick);

        /* send the nick change to servers.. */
        if(IsPerson(source_p))
        {
                add_history(source_p, 1);

                if (dosend)
                {
                        sendto_server(client_p, NULL, CAP_TS6, NOCAPS, ":%s NICK %s :%ld",
                                        use_id(source_p), nick, (long) source_p->tsinfo);
                        sendto_server(client_p, NULL, NOCAPS, CAP_TS6, ":%s NICK %s :%ld",
                                        source_p->name, nick, (long) source_p->tsinfo);
                }
        }

        /* Finally, add to hash */
        del_from_client_hash(source_p->name, source_p);
        strcpy(source_p->user->nick, nick);
        add_to_client_hash(nick, source_p);

        if(!samenick)
                monitor_signon(source_p);

        /* Make sure everyone that has this client on its accept list
         * loses that reference. 
         */
        /* we used to call del_all_accepts() here, but theres no real reason
         * to clear a clients own list of accepted clients.  So just remove
         * them from everyone elses list --anfl
         */
        DLINK_FOREACH_SAFE(ptr, next_ptr, source_p->on_allow_list.head)
        {
                target_p = ptr->data;

                dlinkFindDestroy(source_p, &target_p->localClient->allow_list);
                dlinkDestroy(ptr, &source_p->on_allow_list);
        }

        /* fd_desc is long enough */
        comm_note(client_p->localClient->fd, "Nick: %s", nick);

        return;
}

/*
 * change_remote_nick()
 */
static int
change_remote_nick(struct Client *client_p, struct Client *source_p,
                time_t newts, const char *nick, int dosend)
{
        struct nd_entry *nd;
        int samenick = irccmp(source_p->name, nick) ? 0 : 1;

        /* client changing their nick - dont reset ts if its same */
        if(!samenick)
        {
                source_p->tsinfo = newts ? newts : CurrentTime;
                monitor_signoff(source_p);
        }

        sendto_common_channels_local(source_p, ":%s!%s@%s NICK :%s",
                                     source_p->name, source_p->username,
                                     source_p->host, nick);

        if(source_p->user)
        {
                add_history(source_p, 1);
                if (dosend)
                {
                        sendto_server(client_p, NULL, CAP_TS6, NOCAPS, ":%s NICK %s :%ld",
                                        use_id(source_p), nick, (long) source_p->tsinfo);
                        sendto_server(client_p, NULL, NOCAPS, CAP_TS6, ":%s NICK %s :%ld",
                                        source_p->name, nick, (long) source_p->tsinfo);
                }
        }

        del_from_client_hash(source_p->name, source_p);

        /* invalidate nick delay when a remote client uses the nick.. */
        if((nd = hash_find_nd(nick)))
                free_nd_entry(nd);

        strcpy(source_p->user->nick, nick);
        add_to_client_hash(nick, source_p);

        if(!samenick)
                monitor_signon(source_p);

        /* remove all accepts pointing to the client */
        del_all_accepts(source_p);

        return 0;
}

static int
perform_nick_collides(struct Client *source_p, struct Client *client_p,
                      struct Client *target_p, int parc, const char *parv[],
                      time_t newts, const char *nick, const char *uid)
{
        int sameuser;

        /* if we dont have a ts, or their TS's are the same, kill both */
        if(!newts || !target_p->tsinfo || (newts == target_p->tsinfo))
        {
                sendto_realops_flags(UMODE_ALL, L_ALL,
                                     "Nick collision on %s(%s <- %s)(both killed)",
                                     target_p->name, target_p->from->name, client_p->name);

                sendto_one_numeric(target_p, ERR_NICKCOLLISION,
                                   form_str(ERR_NICKCOLLISION), target_p->name);

                /* if the new client being introduced has a UID, we need to
                 * issue a KILL for it..
                 */
                if(uid)
                        sendto_one(client_p, ":%s KILL %s :%s (Nick collision (new))",
                                        me.id, uid, me.name);

                /* we then need to KILL the old client everywhere */
                kill_client_serv_butone(NULL, target_p,
                                        "%s (Nick collision (new))", me.name);
                ServerStats->is_kill++;

                target_p->flags |= FLAGS_KILLED;
                exit_client(client_p, target_p, &me, "Nick collision (new)");
                return 0;
        }
        /* the timestamps are different */
        else
        {
                sameuser = (target_p->user) && !irccmp(target_p->username, parv[5])
                                && !irccmp(target_p->host, parv[6]);

                if((sameuser && newts < target_p->tsinfo) ||
                   (!sameuser && newts > target_p->tsinfo))
                {
                        /* if we have a UID, then we need to issue a KILL,
                         * otherwise we do nothing and hope that the other
                         * client will collide it..
                         */
                        if(uid)
                                sendto_one(client_p,
                                        ":%s KILL %s :%s (Nick collision (new))",
                                        me.id, uid, me.name);
                        return 0;
                }
                else
                {
                        if(sameuser)
                                sendto_realops_flags(UMODE_ALL, L_ALL,
                                                     "Nick collision on %s(%s <- %s)(older killed)",
                                                     target_p->name, target_p->from->name,
                                                     client_p->name);
                        else
                                sendto_realops_flags(UMODE_ALL, L_ALL,
                                                     "Nick collision on %s(%s <- %s)(newer killed)",
                                                     target_p->name, target_p->from->name,
                                                     client_p->name);

                        ServerStats->is_kill++;
                        sendto_one_numeric(target_p, ERR_NICKCOLLISION,
                                           form_str(ERR_NICKCOLLISION), target_p->name);

                        /* now we just need to kill the existing client */
                        kill_client_serv_butone(client_p, target_p,
                                                "%s (Nick collision (new))", me.name);

                        target_p->flags |= FLAGS_KILLED;
                        (void) exit_client(client_p, target_p, &me, "Nick collision");

                        register_client(client_p, parc == 10 ? source_p : NULL,
                                        nick, newts, parc, parv);

                        return 0;
                }
        }
}


static int
perform_nickchange_collides(struct Client *source_p, struct Client *client_p,
                            struct Client *target_p, int parc, 
                            const char *parv[], time_t newts, const char *nick)
{
        int sameuser;

        /* its a client changing nick and causing a collide */
        if(!newts || !target_p->tsinfo || (newts == target_p->tsinfo) || !source_p->user)
        {
                sendto_realops_flags(UMODE_ALL, L_ALL,
                                     "Nick change collision from %s to %s(%s <- %s)(both killed)",
                                     source_p->name, target_p->name, target_p->from->name,
                                     client_p->name);

                ServerStats->is_kill++;
                sendto_one_numeric(target_p, ERR_NICKCOLLISION,
                                   form_str(ERR_NICKCOLLISION), target_p->name);

                kill_client_serv_butone(NULL, source_p, "%s (Nick change collision)", me.name);

                ServerStats->is_kill++;

                kill_client_serv_butone(NULL, target_p, "%s (Nick change collision)", me.name);

                target_p->flags |= FLAGS_KILLED;
                exit_client(NULL, target_p, &me, "Nick collision(new)");
                source_p->flags |= FLAGS_KILLED;
                exit_client(client_p, source_p, &me, "Nick collision(old)");
                return 0;
        }
        else
        {
                sameuser = !irccmp(target_p->username, source_p->username) &&
                        !irccmp(target_p->host, source_p->host);

                if((sameuser && newts < target_p->tsinfo) ||
                   (!sameuser && newts > target_p->tsinfo))
                {
                        if(sameuser)
                                sendto_realops_flags(UMODE_ALL, L_ALL,
                                                     "Nick change collision from %s to %s(%s <- %s)(older killed)",
                                                     source_p->name, target_p->name,
                                                     target_p->from->name, client_p->name);
                        else
                                sendto_realops_flags(UMODE_ALL, L_ALL,
                                                     "Nick change collision from %s to %s(%s <- %s)(newer killed)",
                                                     source_p->name, target_p->name,
                                                     target_p->from->name, client_p->name);

                        ServerStats->is_kill++;

                        sendto_one_numeric(target_p, ERR_NICKCOLLISION,
                                           form_str(ERR_NICKCOLLISION), target_p->name);

                        /* kill the client issuing the nickchange */
                        kill_client_serv_butone(client_p, source_p,
                                                "%s (Nick change collision)", me.name);

                        source_p->flags |= FLAGS_KILLED;

                        if(sameuser)
                                exit_client(client_p, source_p, &me, "Nick collision(old)");
                        else
                                exit_client(client_p, source_p, &me, "Nick collision(new)");
                        return 0;
                }
                else
                {
                        if(sameuser)
                                sendto_realops_flags(UMODE_ALL, L_ALL,
                                                     "Nick collision on %s(%s <- %s)(older killed)",
                                                     target_p->name, target_p->from->name,
                                                     client_p->name);
                        else
                                sendto_realops_flags(UMODE_ALL, L_ALL,
                                                     "Nick collision on %s(%s <- %s)(newer killed)",
                                                     target_p->name, target_p->from->name,
                                                     client_p->name);

                        sendto_one_numeric(target_p, ERR_NICKCOLLISION,
                                           form_str(ERR_NICKCOLLISION), target_p->name);

                        /* kill the client who existed before hand */
                        kill_client_serv_butone(client_p, target_p, 
                                        "%s (Nick collision)", me.name);

                        ServerStats->is_kill++;

                        target_p->flags |= FLAGS_KILLED;
                        (void) exit_client(client_p, target_p, &me, "Nick collision");
                }
        }

        change_remote_nick(client_p, source_p, newts, nick, 1);

        return 0;
}

static int
register_client(struct Client *client_p, struct Client *server, 
                const char *nick, time_t newts, int parc, const char *parv[])
{
        struct Client *source_p;
        struct User *user;
        struct nd_entry *nd;
        const char *m;
        int flag;

        source_p = make_client(client_p);
        user = make_user(source_p);

        source_p->hopcount = atoi(parv[2]);
        source_p->tsinfo = newts;

        source_p->name = source_p->user->nick;
        strcpy(source_p->user->nick, nick);
        strlcpy(source_p->username, parv[5], sizeof(source_p->username));
        strlcpy(source_p->host, parv[6], sizeof(source_p->host));

        /* nothing must be done before this point that cant be cleaned up
         * just by doing a free_client(). --fl
         */
        if(parc == 10)
        {
                strlcpy(source_p->info, parv[9], sizeof(source_p->info));
                strlcpy(source_p->sockhost, parv[7], sizeof(source_p->sockhost));
                strlcpy(source_p->id, parv[8], sizeof(source_p->id));
                add_to_id_hash(source_p->id, source_p);
        }
        else
        {
                strlcpy(source_p->info, parv[8], sizeof(source_p->info));

                if((server = find_server(NULL, parv[7])) == NULL)
                {
                        sendto_realops_flags(UMODE_ALL, L_ALL,
                                             "Ghost killed: %s on invalid server %s",
                                             source_p->name, parv[7]);
                        kill_client(client_p, source_p, "%s (Server doesn't exist)", me.name);
                        free_user(source_p->user, source_p);
                        free_client(source_p);
                        return 0;
                }

        }

        dlinkAddTail(source_p, &source_p->node, &global_client_list);

        /* server is guaranteed to exist at this point */
        source_p->servptr = server;
        dlinkAdd(source_p, &source_p->lnode, &source_p->servptr->serv->users);

        /* remove any nd entries for this nick */
        if((nd = hash_find_nd(nick)))
                free_nd_entry(nd);

        add_to_client_hash(nick, source_p);
        add_to_hostname_hash(source_p->host, source_p);
        monitor_signon(source_p);

        m = &parv[4][1];
        while(*m)
        {
                flag = user_modes_from_c_to_bitmask[(unsigned char) *m];

#ifdef ENABLE_SERVICES
                if(flag & UMODE_SERVICE)
                {
                        int hit = 0;
                        dlink_node *ptr;

                        DLINK_FOREACH(ptr, service_list.head)
                        {
                                if(!irccmp((const char *) ptr->data, source_p->servptr->name))
                                {
                                        hit++;
                                        break;
                                }
                        }

                        if(!hit)
                        {
                                m++;
                                continue;
                        }
                }
#endif

                /* increment +i count if theyre invis */
                if(!(source_p->umodes & UMODE_INVISIBLE) &&
                   (flag & UMODE_INVISIBLE))
                        Count.invisi++;

                /* increment opered count if theyre opered */
                if(!(source_p->umodes & UMODE_OPER) && (flag & UMODE_OPER))
                        Count.oper++;

                source_p->umodes |= (flag & SEND_UMODES);
                m++;
        }

        SetRemoteClient(source_p);

        if(++Count.total > Count.max_tot)
                Count.max_tot = Count.total;

        /* fake direction */
        if(source_p->servptr->from != source_p->from)
        {
                struct Client *target_p = source_p->servptr->from;

                sendto_realops_flags(UMODE_DEBUG, L_ALL,
                                     "Bad User [%s] :%s USER %s@%s %s, != %s[%s]",
                                     client_p->name, source_p->name,
                                     source_p->username, source_p->host,
                                     source_p->servptr->name, target_p->name,
                                     target_p->from->name);
                kill_client(client_p, source_p,
                            "%s (NICK from wrong direction (%s != %s))",
                            me.name, source_p->servptr->name, target_p->from->name);
                source_p->flags |= FLAGS_KILLED;
                return exit_client(source_p, source_p, &me, "USER server wrong direction");
        }

        return (introduce_client(client_p, source_p, user, nick));
}

static void
save_user(struct Client *client_p, struct Client *source_p,
                struct Client *target_p)
{
        if (!MyConnect(target_p) && (!has_id(target_p) || !IsCapable(target_p->from, CAP_SAVE)))
        {
                /* This shouldn't happen */
                /* Note we only need SAVE support in this direction */
                sendto_realops_flags(UMODE_ALL, L_ALL,
                                "Killed %s!%s@%s for nick collision detected by %s (%s does not support SAVE)",
                                target_p->name, target_p->username, target_p->host, source_p->name, target_p->from->name);
                kill_client_serv_butone(NULL, target_p, "%s (Nick collision (no SAVE support))", me.name);
                ServerStats->is_kill++;

                target_p->flags |= FLAGS_KILLED;
                (void) exit_client(NULL, target_p, &me, "Nick collision (no SAVE support)");
                return;
        }
        sendto_server(client_p, NULL, CAP_SAVE|CAP_TS6, NOCAPS, ":%s SAVE %s %ld",
                        source_p->id, target_p->id, (long)target_p->tsinfo);
        sendto_server(client_p, NULL, CAP_TS6, CAP_SAVE, ":%s NICK %s :%ld",
                        target_p->id, target_p->id, (long)SAVE_NICKTS);
        sendto_server(client_p, NULL, NOCAPS, CAP_TS6, ":%s NICK %s :%ld",
                        target_p->name, target_p->id, (long)SAVE_NICKTS);
        if (!IsMe(client_p))
                sendto_realops_flags(UMODE_SKILL, L_ALL,
                                "Received SAVE message for %s from %s",
                                target_p->name, source_p->name);
        if (MyClient(target_p))
        {
                sendto_one_numeric(target_p, RPL_SAVENICK,
                                form_str(RPL_SAVENICK), target_p->id);
                change_local_nick(target_p, target_p, target_p->id, 0);
                target_p->tsinfo = SAVE_NICKTS;
        }
        else
                change_remote_nick(target_p, target_p, SAVE_NICKTS, target_p->id, 0);
}