/*
  *   IRC - Internet Relay Chat, src/modules/chghost.c
  *   (C) 1999-2001 Carsten Munk (Techie/Stskeeps) <stskeeps@tspre.org>
  *
  *   See file AUTHORS in IRC package for additional names of
  *   the programmers. 
  *
  *   This program is free software; you can redistribute it and/or modify
  *   it under the terms of the GNU General Public License as published by
  *   the Free Software Foundation; either version 1, or (at your option)
  *   any later version.
  *
  *   This program is distributed in the hope that it will be useful,
  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  *   GNU General Public License for more details.
  *
  *   You should have received a copy of the GNU General Public License
  *   along with this program; if not, write to the Free Software
  *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  */
 
 #include "unrealircd.h"
 
 #define MSG_CHGHOST 	"CHGHOST"
 
 CMD_FUNC(cmd_chghost);
 void _userhost_save_current(Client *client);
 void _userhost_changed(Client *client);
 
 long CAP_CHGHOST = 0L;
 
 ModuleHeader MOD_HEADER
   = {
 	"chghost",	/* Name of module */
 	"5.0", /* Version */
 	"/chghost", /* Short description of module */
 	"UnrealIRCd Team",
 	"unrealircd-6",
     };
 
 MOD_TEST()
 {
 	MARK_AS_OFFICIAL_MODULE(modinfo);
 	EfunctionAddVoid(modinfo->handle, EFUNC_USERHOST_SAVE_CURRENT, _userhost_save_current);
 	EfunctionAddVoid(modinfo->handle, EFUNC_USERHOST_CHANGED, _userhost_changed);
 	return MOD_SUCCESS;
 }
 
 MOD_INIT()
 {
 	ClientCapabilityInfo c;
 
 	CommandAdd(modinfo->handle, MSG_CHGHOST, cmd_chghost, MAXPARA, CMD_USER|CMD_SERVER);
 	MARK_AS_OFFICIAL_MODULE(modinfo);
 
 	memset(&c, 0, sizeof(c));
 	c.name = "chghost";
 	ClientCapabilityAdd(modinfo->handle, &c, &CAP_CHGHOST);
 
 	return MOD_SUCCESS;
 }
 
 MOD_LOAD()
 {
 	return MOD_SUCCESS;
 	
 }
 
 MOD_UNLOAD()
 {
 	return MOD_SUCCESS;	
 }
 
 
 static char remember_nick[NICKLEN+1];
 static char remember_user[USERLEN+1];
 static char remember_host[HOSTLEN+1];
 
 /** Save current nick/user/host. Used later by userhost_changed(). */
 void _userhost_save_current(Client *client)
 {
 	strlcpy(remember_nick, client->name, sizeof(remember_nick));
 	strlcpy(remember_user, client->user->username, sizeof(remember_user));
 	strlcpy(remember_host, GetHost(client), sizeof(remember_host));
 }
 
 /** User/Host changed for user.
  * Note that userhost_save_current() needs to be called before this
  * to save the old username/hostname.
  * This userhost_changed() function deals with notifying local clients
  * about the user/host change by sending PART+JOIN+MODE if
  * set::allow-userhost-change force-rejoin is in use,
  * and it wills end "CAP chghost" to such capable clients.
  * It will also deal with bumping fakelag for the user since a user/host
  * change is costly, doesn't matter if it was self-induced or not.
  *
  * Please call this function for any user/host change by doing:
  * userhost_save_current(client);
  * << change username or hostname here >>
  * userhost_changed(client);
  */
 void _userhost_changed(Client *client)
 {
 	Membership *channels;
 	Member *lp;
 	Client *acptr;
 	int impact = 0;
 	char buf[512];
 	long CAP_EXTENDED_JOIN = ClientCapabilityBit("extended-join");
 
 	if (strcmp(remember_nick, client->name))
 	{
 		unreal_log(ULOG_ERROR, "main", "BUG_USERHOST_CHANGED", client,
 		           "[BUG] userhost_changed() was called but without calling userhost_save_current() first! Affected user: $client\n"
 		           "Please report above bug on https://bugs.unrealircd.org/");
 		return; /* We cannot safely process this request anymore */
 	}
 
 	/* It's perfectly acceptable to call us even if the userhost didn't change. */
 	if (!strcmp(remember_user, client->user->username) && !strcmp(remember_host, GetHost(client)))
 		return; /* Nothing to do */
 
 	/* Most of the work is only necessary for set::allow-userhost-change force-rejoin */
 	if (UHOST_ALLOWED == UHALLOW_REJOIN)
 	{
 		/* Walk through all channels of this user.. */
 		for (channels = client->user->channel; channels; channels = channels->next)
 		{
 			Channel *channel = channels->channel;
 			char *modes;
 			char partbuf[512]; /* PART */
 			char joinbuf[512]; /* JOIN */
 			char exjoinbuf[512]; /* JOIN (for CAP extended-join) */
 			char modebuf[512]; /* MODE (if any) */
 			int chanops_only = invisible_user_in_channel(client, channel);
 
 			modebuf[0] = '\0';
 
 			/* If the user is banned, don't send any rejoins, it would only be annoying */
 			if (is_banned(client, channel, BANCHK_JOIN, NULL, NULL))
 				continue;
 
 			/* Prepare buffers for PART, JOIN, MODE */
 			ircsnprintf(partbuf, sizeof(partbuf), ":%s!%s@%s PART %s :%s",
 						remember_nick, remember_user, remember_host,
 						channel->name,
 						"Changing host");
 
 			ircsnprintf(joinbuf, sizeof(joinbuf), ":%s!%s@%s JOIN %s",
 						client->name, client->user->username, GetHost(client), channel->name);
 
 			ircsnprintf(exjoinbuf, sizeof(exjoinbuf), ":%s!%s@%s JOIN %s %s :%s",
 				client->name, client->user->username, GetHost(client), channel->name,
 				IsLoggedIn(client) ? client->user->account : "*",
 				client->info);
 
 			modes = get_chmodes_for_user(client, channels->member_modes);
 			if (!BadPtr(modes))
 				ircsnprintf(modebuf, sizeof(modebuf), ":%s MODE %s %s", me.name, channel->name, modes);
 
 			for (lp = channel->members; lp; lp = lp->next)
 			{
 				acptr = lp->client;
 
 				if (acptr == client)
 					continue; /* skip self */
 
 				if (!MyConnect(acptr))
 					continue; /* only locally connected clients */
 
 				if (chanops_only && !check_channel_access_member(lp, "hoaq"))
 					continue; /* skip non-ops if requested to (used for mode +D) */
 
 				if (HasCapabilityFast(acptr, CAP_CHGHOST))
 					continue; /* we notify 'CAP chghost' users in a different way, so don't send it here. */
 
 				impact++;
 
 				/* FIXME: if a client does not have the "chghost" cap then
 				 * here we will not generate a proper new message, probably
 				 * needs to be fixed... I skipped doing it for now.
 				 */
 				sendto_one(acptr, NULL, "%s", partbuf);
 
 				if (HasCapabilityFast(acptr, CAP_EXTENDED_JOIN))
 					sendto_one(acptr, NULL, "%s", exjoinbuf);
 				else
 					sendto_one(acptr, NULL, "%s", joinbuf);
 
 				if (*modebuf)
 					sendto_one(acptr, NULL, "%s", modebuf);
 			}
 		}
 	}
 
 	/* Now deal with "CAP chghost" clients.
 	 * This only needs to be sent one per "common channel".
 	 * This would normally call sendto_common_channels_local_butone() but the user already
 	 * has the new user/host.. so we do it here..
 	 */
 	ircsnprintf(buf, sizeof(buf), ":%s!%s@%s CHGHOST %s %s",
 	            remember_nick, remember_user, remember_host,
 	            client->user->username,
 	            GetHost(client));
 	current_serial++;
 	for (channels = client->user->channel; channels; channels = channels->next)
 	{
 		for (lp = channels->channel->members; lp; lp = lp->next)
 		{
 			acptr = lp->client;
 			if (MyUser(acptr) && HasCapabilityFast(acptr, CAP_CHGHOST) &&
 			    (acptr->local->serial != current_serial) && (client != acptr))
 			{
 				/* FIXME: send mtag */
 				sendto_one(acptr, NULL, "%s", buf);
 				acptr->local->serial = current_serial;
 			}
 		}
 	}
 	
 	RunHook(HOOKTYPE_USERHOST_CHANGE, client, remember_user, remember_host);
 
 	if (MyUser(client))
 	{
 		/* We take the liberty of sending the CHGHOST to the impacted user as
 		 * well. This makes things easy for client coders.
 		 * (Note that this cannot be merged with the for loop from 15 lines up
 		 *  since the user may not be in any channels)
 		 */
 		if (HasCapabilityFast(client, CAP_CHGHOST))
 			sendto_one(client, NULL, "%s", buf);
 
 		if (MyUser(client))
 			sendnumeric(client, RPL_HOSTHIDDEN, GetHost(client));
 
 		/* A userhost change always generates the following network traffic:
 		 * server to server traffic, CAP "chghost" notifications, and
 		 * possibly PART+JOIN+MODE if force-rejoin had work to do.
 		 * We give the user a penalty so they don't flood...
 		 */
 		if (impact)
 			add_fake_lag(client, 7000); /* Resulted in rejoins and such. */
 		else
 			add_fake_lag(client, 4000); /* No rejoins */
 	}
 }
 
 /* 
  * cmd_chghost - 12/07/1999 (two months after I made SETIDENT) - Stskeeps
  * :prefix CHGHOST <nick> <new hostname>
  * parv[1] - target user
  * parv[2] - hostname
  *
 */
 
 CMD_FUNC(cmd_chghost)
 {
 	Client *target;
 
 	if (MyUser(client) && !ValidatePermissionsForPath("client:set:host",client,NULL,NULL,NULL))
 	{
 		sendnumeric(client, ERR_NOPRIVILEGES);
 		return;
 	}
 
 	if ((parc < 3) || BadPtr(parv[2]))
 	{
 		sendnumeric(client, ERR_NEEDMOREPARAMS, "CHGHOST");
 		return;
 	}
 
 	if (strlen(parv[2]) > (HOSTLEN))
 	{
 		sendnotice(client, "*** ChgName Error: Requested hostname too long -- rejected.");
 		return;
 	}
 
 	if (!valid_host(parv[2], 0))
 	{
 		sendnotice(client, "*** /ChgHost Error: A hostname may contain a-z, A-Z, 0-9, '-' & '.' - Please only use them");
 		return;
 	}
 
 	if (parv[2][0] == ':')
 	{
 		sendnotice(client, "*** A hostname cannot start with ':'");
 		return;
 	}
 
 	target = find_client(parv[1], NULL);
 	if (!MyUser(client) && !target && (target = find_server_by_uid(parv[1])))
 	{
 		/* CHGHOST for a UID that is not online.
 		 * Let's assume it may not YET be online and forward the message to
 		 * the remote server and stop processing ourselves.
 		 * That server will then handle pre-registered processing of the
 		 * CHGHOST and later communicate the host when the user actually
 		 * comes online in the UID message.
 		 */
 		sendto_one(target, recv_mtags, ":%s CHGHOST %s %s", client->id, parv[1], parv[2]);
 		return;
 	}
 
 	if (!target || !target->user)
 	{
 		sendnumeric(client, ERR_NOSUCHNICK, parv[1]);
 		return;
 	}
 
 	if (!strcmp(GetHost(target), parv[2]))
 	{
 		sendnotice(client, "*** /ChgHost Error: requested host is same as current host.");
 		return;
 	}
 
 	userhost_save_current(target);
 
 	switch (UHOST_ALLOWED)
 	{
 		case UHALLOW_NEVER:
 			if (MyUser(client))
 			{
 				sendnumeric(client, ERR_DISABLED, "CHGHOST",
 					"This command is disabled on this server");
 				return;
 			}
 			break;
 		case UHALLOW_ALWAYS:
 			break;
 		case UHALLOW_NOCHANS:
 			if (IsUser(target) && MyUser(client) && target->user->joined)
 			{
 				sendnotice(client, "*** /ChgHost can not be used while %s is on a channel", target->name);
 				return;
 			}
 			break;
 		case UHALLOW_REJOIN:
 			/* rejoin sent later when the host has been changed */
 			break;
 	}
 
 	if (!IsULine(client))
 	{
 		const char *issuer = command_issued_by_rpc(recv_mtags);
 		if (issuer)
 		{
 			unreal_log(ULOG_INFO, "chgcmds", "CHGHOST_COMMAND", client,
 				   "CHGHOST: $issuer changed the virtual hostname of $target.details to be $new_hostname",
 				   log_data_string("issuer", issuer),
 				   log_data_string("change_type", "hostname"),
 				   log_data_client("target", target),
 				   log_data_string("new_hostname", parv[2]));
 		} else {
 			unreal_log(ULOG_INFO, "chgcmds", "CHGHOST_COMMAND", client,
 				   "CHGHOST: $client changed the virtual hostname of $target.details to be $new_hostname",
 				   log_data_string("change_type", "hostname"),
 				   log_data_client("target", target),
 				   log_data_string("new_hostname", parv[2]));
 		}
 	}
 
 	target->umodes |= UMODE_HIDE;
 	target->umodes |= UMODE_SETHOST;
 
 	/* Send to other servers too, unless the client is still in the registration phase (SASL) */
 	if (IsUser(target))
 		sendto_server(client, 0, 0, recv_mtags, ":%s CHGHOST %s %s", client->id, target->id, parv[2]);
 
 	safe_strdup(target->user->virthost, parv[2]);
 	userhost_changed(target);
 }

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