--- a/plugins/muc/mod_muc.lua	Sun Oct 20 20:58:19 2019 +0200
+++ b/plugins/muc/mod_muc.lua	Sun Oct 20 21:58:16 2019 +0200
@@ -86,6 +86,12 @@
 room_mt.get_registered_jid = register.get_registered_jid;
 room_mt.handle_register_iq = register.handle_register_iq;
 
+local presence_broadcast = module:require "muc/presence_broadcast";
+room_mt.get_presence_broadcast = presence_broadcast.get;
+room_mt.set_presence_broadcast = presence_broadcast.set;
+room_mt.get_valid_broadcast_roles = presence_broadcast.get_valid_broadcast_roles;
+
+
 local jid_split = require "util.jid".split;
 local jid_bare = require "util.jid".bare;
 local st = require "util.stanza";
@@ -263,6 +269,7 @@
 	room:set_changesubject(module:get_option_boolean("muc_room_default_change_subject", room:get_changesubject()));
 	room:set_historylength(module:get_option_number("muc_room_default_history_length", room:get_historylength()));
 	room:set_language(lang or module:get_option_string("muc_room_default_language"));
+	room:set_presence_broadcast(module:get_option("muc_room_default_presence_broadcast", room:get_presence_broadcast()));
 end
 
 function create_room(room_jid, config)

--- a/plugins/muc/muc.lib.lua	Sun Oct 20 20:58:19 2019 +0200
+++ b/plugins/muc/muc.lib.lua	Sun Oct 20 21:58:16 2019 +0200
@@ -218,13 +218,13 @@
 
 -- Broadcasts an occupant's presence to the whole room
 -- Takes the x element that goes into the stanzas
-function room_mt:publicise_occupant_status(occupant, x, nick, actor, reason)
+function room_mt:publicise_occupant_status(occupant, x, nick, actor, reason, prev_role, force_unavailable)
 	local base_x = x.base or x;
 	-- Build real jid and (optionally) occupant jid template presences
 	local base_presence do
 		-- Try to use main jid's presence
 		local pr = occupant:get_presence();
-		if pr and (occupant.role ~= nil or pr.attr.type == "unavailable") then
+		if pr and (occupant.role ~= nil or pr.attr.type == "unavailable") and not force_unavailable then
 			base_presence = st.clone(pr);
 		else -- user is leaving but didn't send a leave presence. make one for them
 			base_presence = st.presence {from = occupant.nick; type = "unavailable";};
@@ -280,6 +280,8 @@
 		self_p = st.clone(base_presence):add_child(self_x);
 	end
 
+	local broadcast_roles = self:get_presence_broadcast();
+
 	-- General populace
 	for occupant_nick, n_occupant in self:each_occupant() do
 		if occupant_nick ~= occupant.nick then
@@ -291,7 +293,13 @@
 			else
 				pr = get_anon_p();
 			end
-			self:route_to_occupant(n_occupant, pr);
+			if broadcast_roles[occupant.role or "none"] or force_unavailable then
+				self:route_to_occupant(n_occupant, pr);
+			elseif prev_role and broadcast_roles[prev_role] then
+				pr.attr.type = 'unavailable';
+				self:route_to_occupant(n_occupant, pr);
+			end
+
 		end
 	end
 
@@ -315,6 +323,7 @@
 	local to_bare = jid_bare(to);
 	local is_anonymous = false;
 	local whois = self:get_whois();
+	local broadcast_roles = self:get_presence_broadcast();
 	if whois ~= "anyone" then
 		local affiliation = self:get_affiliation(to);
 		if affiliation ~= "admin" and affiliation ~= "owner" then
@@ -331,7 +340,9 @@
 			local pres = st.clone(occupant:get_presence());
 			pres.attr.to = to;
 			pres:add_child(x);
-			self:route_stanza(pres);
+			if to_bare == occupant.bare_jid or broadcast_roles[occupant.role or "none"] then
+				self:route_stanza(pres);
+			end
 		end
 	end
 end
@@ -1442,9 +1453,11 @@
 	if not role then
 		x:tag("status", {code = "307"}):up();
 	end
+
+	local prev_role = occupant.role;
 	occupant.role = role;
 	self:save_occupant(occupant);
-	self:publicise_occupant_status(occupant, x, nil, actor, reason);
+	self:publicise_occupant_status(occupant, x, nil, actor, reason, prev_role);
 	if role == nil then
 		module:fire_event("muc-occupant-left", {
 				room = self;

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/plugins/muc/presence_broadcast.lib.lua	Sun Oct 20 21:58:16 2019 +0200
@@ -0,0 +1,87 @@
+-- Prosody IM
+-- Copyright (C) 2008-2010 Matthew Wild
+-- Copyright (C) 2008-2010 Waqas Hussain
+-- Copyright (C) 2014 Daurnimator
+--
+-- This project is MIT/X11 licensed. Please see the
+-- COPYING file in the source package for more information.
+--
+
+local st = require "util.stanza";
+
+local valid_roles = { "visitor", "participant", "moderator" };
+local default_broadcast = {
+	none = true;
+	visitor = true;
+	participant = true;
+	moderator = true;
+};
+
+local function get_presence_broadcast(room)
+	return room._data.presence_broadcast or default_broadcast;
+end
+
+local function set_presence_broadcast(room, broadcast_roles)
+	broadcast_roles = broadcast_roles or default_broadcast;
+
+	-- Ensure that unavailable presence is always sent when role changes to none
+	broadcast_roles.none = true;
+
+	local changed = false;
+	local old_broadcast_roles = get_presence_broadcast(room);
+	for _, role in ipairs(valid_roles) do
+		if old_broadcast_roles[role] ~= broadcast_roles[role] then
+			changed = true;
+		end
+	end
+
+	if not changed then return false; end
+
+	room._data.presence_broadcast = broadcast_roles;
+
+	for _, occupant in room:each_occupant() do
+		local x = st.stanza("x", {xmlns = "http://jabber.org/protocol/muc#user";});
+		local role = occupant.role or "none";
+		if broadcast_roles[role] and not old_broadcast_roles[role] then
+			-- Presence broadcast is now enabled, so announce existing user
+			room:publicise_occupant_status(occupant, x);
+		elseif old_broadcast_roles[role] and not broadcast_roles[role] then
+			-- Presence broadcast is now disabled, so mark existing user as unavailable
+			room:publicise_occupant_status(occupant, x, nil, nil, nil, nil, true);
+		end
+	end
+
+	return true;
+end
+
+module:hook("muc-config-form", function(event)
+	local values = {};
+	for role, value in pairs(get_presence_broadcast(event.room)) do
+		if value then
+			values[#values + 1] = role;
+		end
+	end
+
+	table.insert(event.form, {
+		name = "muc#roomconfig_presencebroadcast";
+		type = "list-multi";
+		label = "Roles for which Presence is Broadcasted";
+		value = values;
+		options = valid_roles;
+	});
+end, 70-7);
+
+module:hook("muc-config-submitted/muc#roomconfig_presencebroadcast", function(event)
+	local broadcast_roles = {};
+	for _, role in ipairs(event.value) do
+		broadcast_roles[role] = true;
+	end
+	if set_presence_broadcast(event.room, broadcast_roles) then
+		event.status_codes["104"] = true;
+	end
+end);
+
+return {
+	get = get_presence_broadcast;
+	set = set_presence_broadcast;
+};