/*
  * timedban - Timed bans that are automatically unset.
  * (C) Copyright 2009-2017 Bram Matthys (Syzop) and the UnrealIRCd team.
  * License: GPLv2 or later
  *
  * This module adds an extended ban ~t:time:mask
  * Where 'time' is the time in minutes after which the ban will be removed.
  * Where 'mask' is any banmask that is normally valid.
  *
  * Note that this extended ban is rather special in the sense that
  * it permits (crazy) triple-extbans to be set, such as:
  * +b ~t:1:~q:~a:Account
  * (=a temporary 1min ban to mute a user with services account Account)
  * +e ~t:1440:~m:moderated:*!*@host
  * (=user with *!*@host may speak through +m for the next 1440m / 24h)
  *
  * The triple-extbans / double-stacking requires special routines that
  * are based on parts of the core and special recursion checks.
  * If you are looking for inspiration of coding your own extended ban
  * then look at another extended ban * module as this module is not a
  * good starting point ;)
  */
    
 #include "unrealircd.h"
 
 /* Maximum time (in minutes) for a ban */
 #define TIMEDBAN_MAX_TIME	9999
 
 /* Maximum length of a ban */
 #define MAX_LENGTH 128
 
 /* Split timeout event in <this> amount of iterations */
 #define TIMEDBAN_TIMER_ITERATION_SPLIT 4
 
 /* Call timeout event every <this> seconds.
  * NOTE: until all channels are processed it takes
  *       TIMEDBAN_TIMER_ITERATION_SPLIT * TIMEDBAN_TIMER.
  */
 #define TIMEDBAN_TIMER	2
 
 /* We allow a ban to (potentially) expire slightly before the deadline.
  * For example with TIMEDBAN_TIMER_ITERATION_SPLIT=4 and TIMEDBAN_TIMER=2
  * a 1 minute ban would expire at 56-63 seconds, rather than 60-67 seconds.
  * This is usually preferred.
  */
 #define TIMEDBAN_TIMER_DELTA ((TIMEDBAN_TIMER_ITERATION_SPLIT*TIMEDBAN_TIMER)/2)
 
 ModuleHeader MOD_HEADER
   = {
 	"extbans/timedban",
 	"1.0",
 	"ExtBan ~t: automatically removed timed bans",
 	"UnrealIRCd Team",
 	"unrealircd-6",
     };
 
 /* Forward declarations */
 const char *timedban_extban_conv_param(BanContext *b, Extban *extban);
 int timedban_extban_is_ok(BanContext *b);
 int timedban_is_banned(BanContext *b);
 void add_send_mode_param(Channel *channel, Client *from, char what, char mode, char *param);
 char *timedban_chanmsg(Client *, Client *, Channel *, char *, int);
 
 EVENT(timedban_timeout);
 
 MOD_TEST()
 {
 	return MOD_SUCCESS;
 }
 
 MOD_INIT()
 {
 	ExtbanInfo extban;
 
 	MARK_AS_OFFICIAL_MODULE(modinfo);
 
 	memset(&extban, 0, sizeof(ExtbanInfo));
 	extban.letter = 't';
 	extban.name = "time";
 	extban.options |= EXTBOPT_ACTMODIFIER; /* not really, but ours shouldn't be stacked from group 1 */
 	extban.options |= EXTBOPT_INVEX; /* also permit timed invite-only exceptions (+I) */
 	extban.conv_param = timedban_extban_conv_param;
 	extban.is_ok = timedban_extban_is_ok;
 	extban.is_banned = timedban_is_banned;
 	extban.is_banned_events = BANCHK_ALL;
 
 	if (!ExtbanAdd(modinfo->handle, extban))
 	{
 		config_error("timedban: unable to register 't' extban type!!");
 		return MOD_FAILED;
 	}
                 
 	EventAdd(modinfo->handle, "timedban_timeout", timedban_timeout, NULL, TIMEDBAN_TIMER*1000, 0);
 
 	return MOD_SUCCESS;
 }
 
 MOD_LOAD()
 {
 	return MOD_SUCCESS;
 }
 
 MOD_UNLOAD()
 {
 	return MOD_SUCCESS;
 }
 
 /** Generic helper for our conv_param extban function.
  * Mostly copied from clean_ban_mask()
  * FIXME: Figure out why we have this one at all and not use conv_param? ;)
  */
 const char *generic_clean_ban_mask(BanContext *b, Extban *extban)
 {
 	char *cp, *x;
 	static char maskbuf[512];
 	char *mask;
 
 	/* Work on a copy */
 	strlcpy(maskbuf, b->banstr, sizeof(maskbuf));
 	mask = maskbuf;
 
 	cp = strchr(mask, ' ');
 	if (cp)
 		*cp = '\0';
 
 	/* Strip any ':' at beginning since that would cause a desync */
 	for (; (*mask && (*mask == ':')); mask++);
 	if (!*mask)
 		return NULL;
 
 	/* Forbid ASCII <= 32 in all bans */
 	for (x = mask; *x; x++)
 		if (*x <= ' ')
 			return NULL;
 
 	/* Extended ban? */
 	if (is_extended_ban(mask))
 	{
 		const char *nextbanstr;
 		Extban *extban = findmod_by_bantype(mask, &nextbanstr);
 		if (!extban)
 			return NULL; /* reject unknown extban */
 		if (extban->conv_param)
 		{
 			const char *ret;
 			static char retbuf[512];
 			BanContext *newb = safe_alloc(sizeof(BanContext));
 			newb->banstr = nextbanstr;
 			newb->ban_type = b->ban_type;
 			newb->conv_options = b->conv_options;
 			newb->client = b->client;
 			newb->channel = b->channel;
 			ret = extban->conv_param(newb, extban);
 			ret = prefix_with_extban(ret, newb, extban, retbuf, sizeof(retbuf));
 			safe_free(newb);
 			return ret;
 		}
 		/* else, do some basic sanity checks and cut it off at 80 bytes */
 		if ((mask[1] != ':') || (mask[2] == '\0'))
 		    return NULL; /* require a ":<char>" after extban type */
 		if (strlen(mask) > 80)
 			mask[80] = '\0';
 		return mask;
 	}
 
 	return convert_regular_ban(mask, NULL, 0);
 }
 
 /** Convert ban to an acceptable format (or return NULL to fully reject it) */
 const char *timedban_extban_conv_param(BanContext *b, Extban *extban)
 {
 	static char retbuf[MAX_LENGTH+1];
 	char para[MAX_LENGTH+1];
 	char tmpmask[MAX_LENGTH+1];
 	char *durationstr; /**< Duration, such as '5' */
 	int duration;
 	char *matchby; /**< Matching method, such as 'n!u@h' */
 	const char *newmask; /**< Cleaned matching method, such as 'n!u@h' */
 	static int timedban_extban_conv_param_recursion = 0;
 	
 	if (timedban_extban_conv_param_recursion)
 		return NULL; /* reject: recursion detected! */
 
 	strlcpy(para, b->banstr, sizeof(para)); /* work on a copy (and truncate it) */
 	
 	/* ~t:duration:n!u@h   for direct matching
 	 * ~t:duration:~x:.... when calling another bantype
 	 */
 
 	durationstr = para;
 	matchby = strchr(para, ':');
 	if (!matchby || !matchby[1])
 		return NULL;
 	*matchby++ = '\0';
 	
 	duration = atoi(durationstr);
 
 	if ((duration <= 0) || (duration > TIMEDBAN_MAX_TIME))
 		return NULL;
 
 	strlcpy(tmpmask, matchby, sizeof(tmpmask));
 	timedban_extban_conv_param_recursion++;
 	//newmask = extban_conv_param_nuh_or_extban(tmpmask);
 	b->banstr = matchby; // this was previously 'tmpmask' but then it's a copy-copy-copy.. :D
 	newmask = generic_clean_ban_mask(b, extban);
 	timedban_extban_conv_param_recursion--;
 	if (!newmask || (strlen(newmask) <= 1))
 		return NULL;
 
 	//snprintf(retbuf, sizeof(retbuf), "~t:%d:%s", duration, newmask);
 	snprintf(retbuf, sizeof(retbuf), "%d:%s", duration, newmask);
 	return retbuf;
 }
 
 int timedban_extban_syntax(Client *client, int checkt, char *reason)
 {
 	if (MyUser(client) && (checkt == EXBCHK_PARAM))
 	{
 		sendnotice(client, "Error when setting timed ban: %s", reason);
 		sendnotice(client, " Syntax: +b ~t:duration:mask");
 		sendnotice(client, "Example: +b ~t:5:nick!user@host");
 		sendnotice(client, "Duration is the time in minutes after which the ban is removed (1-9999)");
 		sendnotice(client, "Valid masks are: nick!user@host or another extban type such as ~a, ~c, ~S, ..");
 	}
 	return 0; /* FAIL: ban rejected */
 }
 
 /** Generic helper for sub-bans, used by our "is this ban ok?" function */
 int generic_ban_is_ok(BanContext *b)
 {
 	if ((b->banstr[0] == '~') && MyUser(b->client))
 	{
 		Extban *extban;
 		const char *nextbanstr;
 
 		/* This portion is copied from clean_ban_mask() */
 		if (is_extended_ban(b->banstr) && MyUser(b->client))
 		{
 			if (RESTRICT_EXTENDEDBANS && !ValidatePermissionsForPath("immune:restrict-extendedbans",b->client,NULL,NULL,NULL))
 			{
 				if (!strcmp(RESTRICT_EXTENDEDBANS, "*"))
 				{
 					if (b->is_ok_check == EXBCHK_ACCESS_ERR)
 						sendnotice(b->client, "Setting/removing of extended bans has been disabled");
 					return 0; /* REJECT */
 				}
 				if (strchr(RESTRICT_EXTENDEDBANS, b->banstr[1]))
 				{
 					if (b->is_ok_check == EXBCHK_ACCESS_ERR)
 						sendnotice(b->client, "Setting/removing of extended bantypes '%s' has been disabled", RESTRICT_EXTENDEDBANS);
 					return 0; /* REJECT */
 				}
 			}
 			/* And next is inspired by cmd_mode */
 			extban = findmod_by_bantype(b->banstr, &nextbanstr);
 			if (extban && extban->is_ok)
 			{
 				b->banstr = nextbanstr;
 				if ((b->is_ok_check == EXBCHK_ACCESS) || (b->is_ok_check == EXBCHK_ACCESS_ERR))
 				{
 					if (!extban->is_ok(b) &&
 					    !ValidatePermissionsForPath("channel:override:mode:extban",b->client,NULL,b->channel,NULL))
 					{
 						return 0; /* REJECT */
 					}
 				} else
 				if (b->is_ok_check == EXBCHK_PARAM)
 				{
 					if (!extban->is_ok(b))
 					{
 						return 0; /* REJECT */
 					}
 				}
 			}
 		}
 	}
 	
 	/* ACCEPT:
 	 * - not an extban; OR
 	 * - extban with NULL is_ok; OR
 	 * - non-existing extban character (handled by conv_param?)
 	 */
 	return 1;
 }
 
 /** Validate ban ("is this ban ok?") */
 int timedban_extban_is_ok(BanContext *b)
 {
 	char para[MAX_LENGTH+1];
 	char tmpmask[MAX_LENGTH+1];
 	char *durationstr; /**< Duration, such as '5' */
 	int duration;
 	char *matchby; /**< Matching method, such as 'n!u@h' */
 	char *newmask; /**< Cleaned matching method, such as 'n!u@h' */
 	static int timedban_extban_is_ok_recursion = 0;
 	int res;
 
 	/* Always permit deletion */
 	if (b->what == MODE_DEL)
 		return 1;
 
 	if (timedban_extban_is_ok_recursion)
 		return 0; /* Recursion detected (~t:1:~t:....) */
 
 	strlcpy(para, b->banstr, sizeof(para)); /* work on a copy (and truncate it) */
 	
 	/* ~t:duration:n!u@h   for direct matching
 	 * ~t:duration:~x:.... when calling another bantype
 	 */
 
 	durationstr = para;
 	matchby = strchr(para, ':');
 	if (!matchby || !matchby[1])
 		return timedban_extban_syntax(b->client, b->is_ok_check, "Invalid syntax");
 	*matchby++ = '\0';
 
 	duration = atoi(durationstr);
 
 	if ((duration <= 0) || (duration > TIMEDBAN_MAX_TIME))
 		return timedban_extban_syntax(b->client, b->is_ok_check, "Invalid duration time");
 
 	strlcpy(tmpmask, matchby, sizeof(tmpmask));
 	timedban_extban_is_ok_recursion++;
 	//res = extban_is_ok_nuh_extban(b->client, b->channel, tmpmask, b->is_ok_check, b->what, b->ban_type);
 	b->banstr = tmpmask;
 	res = generic_ban_is_ok(b);
 	timedban_extban_is_ok_recursion--;
 	if (res == 0)
 	{
 		/* This could be anything ranging from:
 		 * invalid n!u@h syntax, unknown (sub)extbantype,
 		 * disabled extban type in conf, too much recursion, etc.
 		 */
 		return timedban_extban_syntax(b->client, b->is_ok_check, "Invalid matcher");
 	}
 
 	return 1; /* OK */
 }
 
 /** Check if the user is currently banned */
 int timedban_is_banned(BanContext *b)
 {
 	b->banstr = strchr(b->banstr, ':'); /* skip time argument */
 	if (!b->banstr)
 		return 0; /* invalid fmt */
 	b->banstr++; /* skip over final semicolon */
 
 	return ban_check_mask(b);
 }
 
 /** Helper to check if the ban has been expired.
  */
 int timedban_has_ban_expired(Ban *ban)
 {
 	char *banstr = ban->banstr;
 	char *p1, *p2;
 	int t;
 	time_t expire_on;
 
 	/* The caller has only performed a very light check (string starting
 	 * with ~t, in the interest of performance), so we don't know yet if
 	 * it REALLY is a timed ban. We check that first here...
 	 */
 	if (!strncmp(banstr, "~t:", 3))
 		p1 = banstr + 3;
 	else if (!strncmp(banstr, "~time:", 6))
 		p1 = banstr + 6;
 	else
 		return 0; /* not for us */
 	p2 = strchr(p1+1, ':'); /* skip time argument */
 	if (!p2)
 		return 0; /* invalid fmt */
 	*p2 = '\0'; /* danger.. must restore!! */
 	t = atoi(p1);
 	*p2 = ':'; /* restored.. */
 	
 	expire_on = ban->when + (t * 60) - TIMEDBAN_TIMER_DELTA;
 	
 	if (expire_on < TStime())
 		return 1;
 	return 0;
 }
 
 static char mbuf[512];
 static char pbuf[512];
 
 /** This removes any expired timedbans */
 EVENT(timedban_timeout)
 {
 	Channel *channel;
 	Ban *ban, *nextban;
 	static int current_iteration = 0;
 
 	if (++current_iteration >= TIMEDBAN_TIMER_ITERATION_SPLIT)
 		current_iteration = 0;
 
 	for (channel = channels; channel; channel = channel->nextch)
 	{
 		/* This is a very quick check, at the cost of it being
 		 * biased since there's always a tendency of more channel
 		 * names to start with one specific letter. But hashing
 		 * is too costly. So we stick with this. It should be
 		 * good enough. Alternative would be some channel->id value.
 		 */
 		if (((unsigned int)channel->name[1] % TIMEDBAN_TIMER_ITERATION_SPLIT) != current_iteration)
 			continue; /* not this time, maybe next */
 
 		*mbuf = *pbuf = '\0';
 		for (ban = channel->banlist; ban; ban=nextban)
 		{
 			nextban = ban->next;
 			if (!strncmp(ban->banstr, "~t", 2) && timedban_has_ban_expired(ban))
 			{
 				add_send_mode_param(channel, &me, '-',  'b', ban->banstr);
 				del_listmode(&channel->banlist, channel, ban->banstr);
 			}
 		}
 		for (ban = channel->exlist; ban; ban=nextban)
 		{
 			nextban = ban->next;
 			if (!strncmp(ban->banstr, "~t", 2) && timedban_has_ban_expired(ban))
 			{
 				add_send_mode_param(channel, &me, '-',  'e', ban->banstr);
 				del_listmode(&channel->exlist, channel, ban->banstr);
 			}
 		}
 		for (ban = channel->invexlist; ban; ban=nextban)
 		{
 			nextban = ban->next;
 			if (!strncmp(ban->banstr, "~t", 2) && timedban_has_ban_expired(ban))
 			{
 				add_send_mode_param(channel, &me, '-',  'I', ban->banstr);
 				del_listmode(&channel->invexlist, channel, ban->banstr);
 			}
 		}
 		if (*pbuf)
 		{
 			MessageTag *mtags = NULL;
 			new_message(&me, NULL, &mtags);
 			sendto_channel(channel, &me, NULL, 0, 0, SEND_LOCAL, mtags, ":%s MODE %s %s %s", me.name, channel->name, mbuf, pbuf);
 			sendto_server(NULL, 0, 0, mtags, ":%s MODE %s %s %s 0", me.id, channel->name, mbuf, pbuf);
 			free_message_tags(mtags);
 			*pbuf = 0;
 		}
 	}
 }
 
 #if MODEBUFLEN > 512
  #error "add_send_mode_param() is not made for MODEBUFLEN > 512"
 #endif
 
 void add_send_mode_param(Channel *channel, Client *from, char what, char mode, char *param) {
 	static char *modes = NULL, lastwhat;
 	static short count = 0;
 	short send = 0;
 	
 	if (!modes) modes = mbuf;
 	
 	if (!mbuf[0]) {
 		modes = mbuf;
 		*modes++ = what;
 		*modes = 0;
 		lastwhat = what;
 		*pbuf = 0;
 		count = 0;
 	}
 	if (lastwhat != what) {
 		*modes++ = what;
 		*modes = 0;
 		lastwhat = what;
 	}
 	if (strlen(pbuf) + strlen(param) + 11 < MODEBUFLEN) {
 		if (*pbuf) 
 			strcat(pbuf, " ");
 		strcat(pbuf, param);
 		*modes++ = mode;
 		*modes = 0;
 		count++;
 	}
 	else if (*pbuf) 
 		send = 1;
 
 	if (count == MAXMODEPARAMS)
 		send = 1;
 
 	if (send)
 	{
 		MessageTag *mtags = NULL;
 
 		new_message(&me, NULL, &mtags);
 		sendto_channel(channel, &me, NULL, 0, 0, SEND_LOCAL, mtags, ":%s MODE %s %s %s", me.name, channel->name, mbuf, pbuf);
 		sendto_server(NULL, 0, 0, mtags, ":%s MODE %s %s %s 0", me.id, channel->name, mbuf, pbuf);
 		free_message_tags(mtags);
 		send = 0;
 		*pbuf = 0;
 		modes = mbuf;
 		*modes++ = what;
 		lastwhat = what;
 		if (count != MAXMODEPARAMS)
 		{
 			strlcpy(pbuf, param, sizeof(pbuf));
 			*modes++ = mode;
 			count = 1;
 		} else {
 			count = 0;
 		}
 		*modes = 0;
 	}
 }

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