--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mod_isolate_host/mod_isolate_host.lua	Tue May 14 16:25:59 2013 +0100
@@ -0,0 +1,43 @@
+local jid = require "util.jid";
+local jid_bare, jid_split = jid.bare, jid.split;
+local is_admin = require "core.usermanager".is_admin;
+local set = require "util.set";
+local st = require "util.stanza";
+
+local stanza_types = set.new{"message", "presence", "iq"};
+local jid_types = set.new{"bare", "full", "host"};
+
+local except_domains = module:get_option_inherited_set("isolate_except_domains", {});
+local except_users = module:get_option_inherited_set("isolate_except_users", {});
+
+function check_stanza(event)
+	local origin, stanza = event.origin, event.stanza;
+	if origin.no_host_isolation then return; end
+	local to_user, to_host = jid_split(event.stanza.attr.to);
+	if to_host and to_host ~= origin.host and not except_domains:contains(to_host) then
+		if to_host:match("^[^.]+%.(.+)$") == origin.host then -- Permit subdomains
+			except_domains:add(to_host);
+			return;
+		end
+		module:log("warn", "Forbidding stanza from %s to %s", stanza.attr.from or origin.full_jid, stanza.attr.to);
+		origin.send(st.error_reply(stanza, "auth", "forbidden", "Communication with "..to_host.." is not available"));
+		return true;
+	end
+end
+
+for stanza_type in stanza_types do
+	for jid_type in jid_types do
+		module:hook("pre-"..stanza_type.."/"..jid_type, check_stanza);
+	end
+end
+
+function check_user_isolated(event)
+	local session = event.session;
+	local bare_jid = jid_bare(session.full_jid);
+	if is_admin(bare_jid, module.host) or except_users:contains(bare_jid) then
+		session.no_host_isolation = true;
+	end
+	module:log("debug", "%s is %sisolated", session.full_jid or "[?]", session.no_host_isolation and "" or "not ");
+end
+
+module:hook("resource-bind", check_user_isolated);