Changeset

--- a/CHANGES	Mon Mar 28 11:08:18 2022 +0100
+++ b/CHANGES	Mon Mar 28 11:08:53 2022 +0100
@@ -1,3 +1,17 @@
+TRUNK
+=====
+
+## New
+
+### Administration
+
+- Add 'watch log' command to follow live debug logs at runtime (even if disabled)
+
+### Networking
+
+- Honour 'weight' parameter during SRV record selection
+- Support for RFC 8305 "Happy Eyeballs" to improve IPv4/IPv6 connectivity
+
 0.12.0
 ======
 

--- a/net/connect.lua	Mon Mar 28 11:08:18 2022 +0100
+++ b/net/connect.lua	Mon Mar 28 11:08:53 2022 +0100
@@ -1,6 +1,7 @@
 local server = require "net.server";
 local log = require "util.logger".init("net.connect");
 local new_id = require "util.id".short;
+local timer = require "util.timer";
 
 -- TODO #1246 Happy Eyeballs
 -- FIXME RFC 6724
@@ -28,16 +29,17 @@
 
 local function attempt_connection(p)
 	p:log("debug", "Checking for targets...");
-	if p.conn then
-		pending_connections_map[p.conn] = nil;
-		p.conn = nil;
-	end
-	p.target_resolver:next(function (conn_type, ip, port, extra)
+	p.target_resolver:next(function (conn_type, ip, port, extra, more_targets_available)
 		if not conn_type then
 			-- No more targets to try
 			p:log("debug", "No more connection targets to try", p.target_resolver.last_error);
-			if p.listeners.onfail then
-				p.listeners.onfail(p.data, p.last_error or p.target_resolver.last_error or "unable to resolve service");
+			if next(p.conns) == nil then
+				p:log("debug", "No more targets, no pending connections. Connection failed.");
+				if p.listeners.onfail then
+					p.listeners.onfail(p.data, p.last_error or p.target_resolver.last_error or "unable to resolve service");
+				end
+			else
+				p:log("debug", "One or more connection attempts are still pending. Waiting for now.");
 			end
 			return;
 		end
@@ -49,8 +51,16 @@
 			p.last_error = err or "unknown reason";
 			return attempt_connection(p);
 		end
-		p.conn = conn;
+		p.conns[conn] = true;
 		pending_connections_map[conn] = p;
+		if more_targets_available then
+			timer.add_task(0.250, function ()
+				if not p.connected then
+					p:log("debug", "Still not connected, making parallel connection attempt...");
+					attempt_connection(p);
+				end
+			end);
+		end
 	end);
 end
 
@@ -62,6 +72,13 @@
 		return;
 	end
 	pending_connections_map[conn] = nil;
+	if p.connected then
+		-- We already succeeded in connecting
+		p.conns[conn] = nil;
+		conn:close();
+		return;
+	end
+	p.connected = true;
 	p:log("debug", "Successfully connected");
 	conn:setlistener(p.listeners, p.data);
 	return p.listeners.onconnect(conn);
@@ -73,9 +90,17 @@
 		log("warn", "Failed connection, but unexpected!");
 		return;
 	end
+	p.conns[conn] = nil;
 	p.last_error = reason or "unknown reason";
 	p:log("debug", "Connection attempt failed: %s", p.last_error);
-	attempt_connection(p);
+	if p.connected then
+		p:log("debug", "Connection already established, ignoring failure");
+	elseif next(p.conns) == nil then
+		p:log("debug", "No pending connection attempts, and not yet connected");
+		attempt_connection(p);
+	else
+		p:log("debug", "Other attempts are still pending, ignoring failure");
+	end
 end
 
 local function connect(target_resolver, listeners, options, data)
@@ -85,6 +110,7 @@
 		listeners = assert(listeners);
 		options = options or {};
 		data = data;
+		conns = {};
 	}, pending_connection_mt);
 
 	p:log("debug", "Starting connection process");

--- a/net/resolvers/basic.lua	Mon Mar 28 11:08:18 2022 +0100
+++ b/net/resolvers/basic.lua	Mon Mar 28 11:08:53 2022 +0100
@@ -2,13 +2,59 @@
 local inet_pton = require "util.net".pton;
 local inet_ntop = require "util.net".ntop;
 local idna_to_ascii = require "util.encodings".idna.to_ascii;
-local unpack = table.unpack or unpack; -- luacheck: ignore 113
+local promise = require "util.promise";
+local t_move = require "util.table".move;
 
 local methods = {};
 local resolver_mt = { __index = methods };
 
 -- FIXME RFC 6724
 
+local function do_dns_lookup(self, dns_resolver, record_type, name)
+	return promise.new(function (resolve, reject)
+		local ipv = (record_type == "A" and "4") or (record_type == "AAAA" and "6") or nil;
+		if ipv and self.extra["use_ipv"..ipv] == false then
+			return reject(("IPv%s disabled - %s lookup skipped"):format(ipv, record_type));
+		elseif record_type == "TLSA" and self.extra.use_dane ~= true then
+			return reject("DANE disabled - TLSA lookup skipped");
+		end
+		dns_resolver:lookup(function (answer, err)
+			if not answer then
+				return reject(err);
+			elseif answer.bogus then
+				return reject(("Validation error in %s lookup"):format(record_type));
+			elseif answer.status and #answer == 0 then
+				return reject(("%s in %s lookup"):format(answer.status, record_type));
+			end
+
+			local targets = { secure = answer.secure };
+			for _, record in ipairs(answer) do
+				if ipv then
+					table.insert(targets, { self.conn_type..ipv, record[record_type:lower()], self.port, self.extra });
+				else
+					table.insert(targets, record[record_type:lower()]);
+				end
+			end
+			return resolve(targets);
+		end, name, record_type, "IN");
+	end);
+end
+
+local function merge_targets(ipv4_targets, ipv6_targets)
+	local result = { secure = ipv4_targets.secure and ipv6_targets.secure };
+	local common_length = math.min(#ipv4_targets, #ipv6_targets);
+	for i = 1, common_length do
+		table.insert(result, ipv6_targets[i]);
+		table.insert(result, ipv4_targets[i]);
+	end
+	if common_length < #ipv4_targets then
+		t_move(ipv4_targets, common_length+1, #ipv4_targets, common_length+1, result);
+	elseif common_length < #ipv6_targets then
+		t_move(ipv6_targets, common_length+1, #ipv6_targets, common_length+1, result);
+	end
+	return result;
+end
+
 -- Find the next target to connect to, and
 -- pass it to cb()
 function methods:next(cb)
@@ -18,7 +64,7 @@
 			return;
 		end
 		local next_target = table.remove(self.targets, 1);
-		cb(unpack(next_target, 1, 4));
+		cb(next_target[1], next_target[2], next_target[3], next_target[4], not not self.targets[1]);
 		return;
 	end
 
@@ -28,91 +74,45 @@
 		return;
 	end
 
-	local secure = true;
-	local tlsa = {};
-	local targets = {};
-	local n = 3;
-	local function ready()
-		n = n - 1;
-		if n > 0 then return; end
-		self.targets = targets;
+	-- Resolve DNS to target list
+	local dns_resolver = adns.resolver();
+
+	local dns_lookups = {
+		ipv4 = do_dns_lookup(self, dns_resolver, "A", self.hostname);
+		ipv6 = do_dns_lookup(self, dns_resolver, "AAAA", self.hostname);
+		tlsa = do_dns_lookup(self, dns_resolver, "TLSA", ("_%d._%s.%s"):format(self.port, self.conn_type, self.hostname));
+	};
+
+	promise.all_settled(dns_lookups):next(function (dns_results)
+		-- Combine targets, assign to self.targets, self:next(cb)
+		local have_ipv4 = dns_results.ipv4.status == "fulfilled";
+		local have_ipv6 = dns_results.ipv6.status == "fulfilled";
+
+		if have_ipv4 and have_ipv6 then
+			self.targets = merge_targets(dns_results.ipv4.value, dns_results.ipv6.value);
+		elseif have_ipv4 then
+			self.targets = dns_results.ipv4.value;
+		elseif have_ipv6 then
+			self.targets = dns_results.ipv6.value;
+		else
+			self.targets = {};
+		end
+
 		if self.extra and self.extra.use_dane then
-			if secure and tlsa[1] then
-				self.extra.tlsa = tlsa;
+			if self.targets.secure and dns_results.tlsa.status == "fulfilled" then
+				self.extra.tlsa = dns_results.tlsa.value;
 				self.extra.dane_hostname = self.hostname;
 			else
 				self.extra.tlsa = nil;
 				self.extra.dane_hostname = nil;
 			end
 		end
+
 		self:next(cb);
-	end
-
-	-- Resolve DNS to target list
-	local dns_resolver = adns.resolver();
-
-	if not self.extra or self.extra.use_ipv4 ~= false then
-		dns_resolver:lookup(function (answer, err)
-			if answer then
-				secure = secure and answer.secure;
-				for _, record in ipairs(answer) do
-					table.insert(targets, { self.conn_type.."4", record.a, self.port, self.extra });
-				end
-				if answer.bogus then
-					self.last_error = "Validation error in A lookup";
-				elseif answer.status then
-					self.last_error = answer.status .. " in A lookup";
-				end
-			else
-				self.last_error = err;
-			end
-			ready();
-		end, self.hostname, "A", "IN");
-	else
-		ready();
-	end
-
-	if not self.extra or self.extra.use_ipv6 ~= false then
-		dns_resolver:lookup(function (answer, err)
-			if answer then
-				secure = secure and answer.secure;
-				for _, record in ipairs(answer) do
-					table.insert(targets, { self.conn_type.."6", record.aaaa, self.port, self.extra });
-				end
-				if answer.bogus then
-					self.last_error = "Validation error in AAAA lookup";
-				elseif answer.status then
-					self.last_error = answer.status .. " in AAAA lookup";
-				end
-			else
-				self.last_error = err;
-			end
-			ready();
-		end, self.hostname, "AAAA", "IN");
-	else
-		ready();
-	end
-
-	if self.extra and self.extra.use_dane == true then
-		dns_resolver:lookup(function (answer, err)
-			if answer then
-				secure = secure and answer.secure;
-				for _, record in ipairs(answer) do
-					table.insert(tlsa, record.tlsa);
-				end
-				if answer.bogus then
-					self.last_error = "Validation error in TLSA lookup";
-				elseif answer.status then
-					self.last_error = answer.status .. " in TLSA lookup";
-				end
-			else
-				self.last_error = err;
-			end
-			ready();
-		end, ("_%d._tcp.%s"):format(self.port, self.hostname), "TLSA", "IN");
-	else
-		ready();
-	end
+	end):catch(function (err)
+		self.last_error = err;
+		self.targets = {};
+	end);
 end
 
 local function new(hostname, port, conn_type, extra)
@@ -137,7 +137,7 @@
 		hostname = ascii_host;
 		port = port;
 		conn_type = conn_type;
-		extra = extra;
+		extra = extra or {};
 		targets = targets;
 	}, resolver_mt);
 end

--- a/net/resolvers/service.lua	Mon Mar 28 11:08:18 2022 +0100
+++ b/net/resolvers/service.lua	Mon Mar 28 11:08:53 2022 +0100
@@ -2,23 +2,78 @@
 local basic = require "net.resolvers.basic";
 local inet_pton = require "util.net".pton;
 local idna_to_ascii = require "util.encodings".idna.to_ascii;
-local unpack = table.unpack or unpack; -- luacheck: ignore 113
 
 local methods = {};
 local resolver_mt = { __index = methods };
 
+local function new_target_selector(rrset)
+	local rr_count = rrset and #rrset;
+	if not rr_count or rr_count == 0 then
+		rrset = nil;
+	else
+		table.sort(rrset, function (a, b) return a.srv.priority < b.srv.priority end);
+	end
+	local rrset_pos = 1;
+	local priority_bucket, bucket_total_weight, bucket_len, bucket_used;
+	return function ()
+		if not rrset then return; end
+
+		if not priority_bucket or bucket_used >= bucket_len then
+			if rrset_pos > rr_count then return; end -- Used up all records
+
+			-- Going to start on a new priority now. Gather up all the next
+			-- records with the same priority and add them to priority_bucket
+			priority_bucket, bucket_total_weight, bucket_len, bucket_used = {}, 0, 0, 0;
+			local current_priority;
+			repeat
+				local curr_record = rrset[rrset_pos].srv;
+				if not current_priority then
+					current_priority = curr_record.priority;
+				elseif current_priority ~= curr_record.priority then
+					break;
+				end
+				table.insert(priority_bucket, curr_record);
+				bucket_total_weight = bucket_total_weight + curr_record.weight;
+				bucket_len = bucket_len + 1;
+				rrset_pos = rrset_pos + 1;
+			until rrset_pos > rr_count;
+		end
+
+		bucket_used = bucket_used + 1;
+		local n, running_total = math.random(0, bucket_total_weight), 0;
+		local target_record;
+		for i = 1, bucket_len do
+			local candidate = priority_bucket[i];
+			if candidate then
+				running_total = running_total + candidate.weight;
+				if running_total >= n then
+					target_record = candidate;
+					bucket_total_weight = bucket_total_weight - candidate.weight;
+					priority_bucket[i] = nil;
+					break;
+				end
+			end
+		end
+		return target_record;
+	end;
+end
+
 -- Find the next target to connect to, and
 -- pass it to cb()
 function methods:next(cb)
-	if self.targets then
-		if not self.resolver then
-			if #self.targets == 0 then
+	if self.resolver or self._get_next_target then
+		if not self.resolver then -- Do we have a basic resolver currently?
+			-- We don't, so fetch a new SRV target, create a new basic resolver for it
+			local next_srv_target = self._get_next_target and self._get_next_target();
+			if not next_srv_target then
+				-- No more SRV targets left
 				cb(nil);
 				return;
 			end
-			local next_target = table.remove(self.targets, 1);
-			self.resolver = basic.new(unpack(next_target, 1, 4));
+			-- Create a new basic resolver for this SRV target
+			self.resolver = basic.new(next_srv_target.target, next_srv_target.port, self.conn_type, self.extra);
 		end
+		-- Look up the next (basic) target from the current target's resolver
 		self.resolver:next(function (...)
 			if self.resolver then
 				self.last_error = self.resolver.last_error;
@@ -31,6 +86,9 @@
 			end
 		end);
 		return;
+	elseif self.in_progress then
+		cb(nil);
+		return;
 	end
 
 	if not self.hostname then
@@ -39,9 +97,9 @@
 		return;
 	end
 
-	local targets = {};
+	self.in_progress = true;
+
 	local function ready()
-		self.targets = targets;
 		self:next(cb);
 	end
 
@@ -63,7 +121,7 @@
 
 			if #answer == 0 then
 				if self.extra and self.extra.default_port then
-					table.insert(targets, { self.hostname, self.extra.default_port, self.conn_type, self.extra });
+					self.resolver = basic.new(self.hostname, self.extra.default_port, self.conn_type, self.extra);
 				else
 					self.last_error = "zero SRV records found";
 				end
@@ -77,10 +135,7 @@
 				return;
 			end
 
-			table.sort(answer, function (a, b) return a.srv.priority < b.srv.priority end);
-			for _, record in ipairs(answer) do
-				table.insert(targets, { record.srv.target, record.srv.port, self.conn_type, self.extra });
-			end
+			self._get_next_target = new_target_selector(answer);
 		else
 			self.last_error = err;
 		end

--- a/plugins/adhoc/adhoc.lib.lua	Mon Mar 28 11:08:18 2022 +0100
+++ b/plugins/adhoc/adhoc.lib.lua	Mon Mar 28 11:08:53 2022 +0100
@@ -34,6 +34,8 @@
 	local cmdtag = stanza.tags[1]
 	local sessionid = cmdtag.attr.sessionid or uuid.generate();
 	local dataIn = {
+		origin = origin;
+		stanza = stanza;
 		to = stanza.attr.to;
 		from = stanza.attr.from;
 		action = cmdtag.attr.action or "execute";

--- a/plugins/adhoc/mod_adhoc.lua	Mon Mar 28 11:08:18 2022 +0100
+++ b/plugins/adhoc/mod_adhoc.lua	Mon Mar 28 11:08:53 2022 +0100
@@ -79,12 +79,12 @@
 		    or (command.permission == "global_admin" and not global_admin)
 		    or (command.permission == "local_user" and hostname ~= module.host) then
 			origin.send(st.error_reply(stanza, "auth", "forbidden", "You don't have permission to execute this command"):up()
-			    :add_child(commands[node]:cmdtag("canceled")
+			    :add_child(command:cmdtag("canceled")
 				:tag("note", {type="error"}):text("You don't have permission to execute this command")));
 			return true
 		end
 		-- User has permission now execute the command
-		adhoc_handle_cmd(commands[node], origin, stanza);
+		adhoc_handle_cmd(command, origin, stanza);
 		return true;
 	end
 end, 500);

--- a/plugins/mod_admin_shell.lua	Mon Mar 28 11:08:18 2022 +0100
+++ b/plugins/mod_admin_shell.lua	Mon Mar 28 11:08:53 2022 +0100
@@ -36,6 +36,7 @@
 local serialize_config = serialization.new ({ fatal = false, unquoted = true});
 local time = require "util.time";
 local promise = require "util.promise";
+local logger = require "util.logger";
 
 local t_insert = table.insert;
 local t_concat = table.concat;
@@ -83,8 +84,8 @@
 	self.data.print("Error: "..tostring(err));
 end
 
-local function send_repl_output(session, line)
-	return session.send(st.stanza("repl-output"):text(tostring(line)));
+local function send_repl_output(session, line, attr)
+	return session.send(st.stanza("repl-output", attr):text(tostring(line)));
 end
 
 function console:new_session(admin_session)
@@ -99,8 +100,14 @@
 			end
 			return send_repl_output(admin_session, table.concat(t, "\t"));
 		end;
+		write = function (t)
+			return send_repl_output(admin_session, t, { eol = "0" });
+		end;
 		serialize = tostring;
 		disconnect = function () admin_session:close(); end;
+		is_connected = function ()
+			return not not admin_session.conn;
+		end
 	};
 	session.env = setmetatable({}, default_env_mt);
 
@@ -1583,6 +1590,26 @@
 	return true;
 end
 
+def_env.watch = {};
+
+function def_env.watch:log()
+	local writing = false;
+	local sink = logger.add_simple_sink(function (source, level, message)
+		if writing then return; end
+		writing = true;
+		self.session.print(source, level, message);
+		writing = false;
+	end);
+
+	while self.session.is_connected() do
+		async.sleep(3);
+	end
+	if not logger.remove_sink(sink) then
+		module:log("warn", "Unable to remove watch:log() sink");
+	end
+end
+
+
 def_env.debug = {};
 
 function def_env.debug:logevents(host)

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/spec/net_resolvers_service_spec.lua	Mon Mar 28 11:08:53 2022 +0100
@@ -0,0 +1,241 @@
+local set = require "util.set";
+
+insulate("net.resolvers.service", function ()
+	local adns = {
+		resolver = function ()
+			return {
+				lookup = function (_, cb, qname, qtype, qclass)
+					if qname == "_xmpp-server._tcp.example.com"
+					   and (qtype or "SRV") == "SRV"
+					   and (qclass or "IN") == "IN" then
+						cb({
+							{ -- 60+35+60
+								srv = { target = "xmpp0-a.example.com", port = 5228, priority = 0, weight = 60 };
+							};
+							{
+								srv = { target = "xmpp0-b.example.com", port = 5216, priority = 0, weight = 35 };
+							};
+							{
+								srv = { target = "xmpp0-c.example.com", port = 5200, priority = 0, weight = 0 };
+							};
+							{
+								srv = { target = "xmpp0-d.example.com", port = 5256, priority = 0, weight = 120 };
+							};
+
+							{
+								srv = { target = "xmpp1-a.example.com", port = 5273, priority = 1, weight = 30 };
+							};
+							{
+								srv = { target = "xmpp1-b.example.com", port = 5274, priority = 1, weight = 30 };
+							};
+
+							{
+								srv = { target = "xmpp2.example.com", port = 5275, priority = 2, weight = 0 };
+							};
+						});
+					elseif qname == "_xmpp-server._tcp.single.example.com"
+					   and (qtype or "SRV") == "SRV"
+					   and (qclass or "IN") == "IN" then
+						cb({
+							{
+								srv = { target = "xmpp0-a.example.com", port = 5269, priority = 0, weight = 0 };
+							};
+						});
+					elseif qname == "_xmpp-server._tcp.half.example.com"
+					   and (qtype or "SRV") == "SRV"
+					   and (qclass or "IN") == "IN" then
+						cb({
+							{
+								srv = { target = "xmpp0-a.example.com", port = 5269, priority = 0, weight = 0 };
+							};
+							{
+								srv = { target = "xmpp0-b.example.com", port = 5270, priority = 0, weight = 1 };
+							};
+						});
+					elseif qtype == "A" then
+						local l = qname:match("%-(%a)%.example.com$") or "1";
+						local d = ("%d"):format(l:byte())
+						cb({
+							{
+								a = "127.0.0."..d;
+							};
+						});
+					elseif qtype == "AAAA" then
+						local l = qname:match("%-(%a)%.example.com$") or "1";
+						local d = ("%04d"):format(l:byte())
+						cb({
+							{
+								aaaa = "fdeb:9619:649e:c7d9::"..d;
+							};
+						});
+					else
+						cb(nil);
+					end
+				end;
+			};
+		end;
+	};
+	package.loaded["net.adns"] = mock(adns);
+	local resolver = require "net.resolvers.service";
+	math.randomseed(os.time());
+	it("works for 99% of deployments", function ()
+		-- Most deployments only have a single SRV record, let's make
+		-- sure that works okay
+
+		local expected_targets = set.new({
+			-- xmpp0-a
+			"tcp4  127.0.0.97  5269";
+			"tcp6  fdeb:9619:649e:c7d9::0097  5269";
+		});
+		local received_targets = set.new({});
+
+		local r = resolver.new("single.example.com", "xmpp-server");
+		local done = false;
+		local function handle_target(...)
+			if ... == nil then
+				done = true;
+				-- No more targets
+				return;
+			end
+			received_targets:add(table.concat({ ... }, "  ", 1, 3));
+		end
+		r:next(handle_target);
+		while not done do
+			r:next(handle_target);
+		end
+
+		-- We should have received all expected targets, and no unexpected
+		-- ones:
+		assert.truthy(set.xor(received_targets, expected_targets):empty());
+	end);
+
+	it("supports A/AAAA fallback", function ()
+		-- Many deployments don't have any SRV records, so we should
+		-- fall back to A/AAAA records instead when that is the case
+
+		local expected_targets = set.new({
+			-- xmpp0-a
+			"tcp4  127.0.0.97  5269";
+			"tcp6  fdeb:9619:649e:c7d9::0097  5269";
+		});
+		local received_targets = set.new({});
+
+		local r = resolver.new("xmpp0-a.example.com", "xmpp-server", "tcp", { default_port = 5269 });
+		local done = false;
+		local function handle_target(...)
+			if ... == nil then
+				done = true;
+				-- No more targets
+				return;
+			end
+			received_targets:add(table.concat({ ... }, "  ", 1, 3));
+		end
+		r:next(handle_target);
+		while not done do
+			r:next(handle_target);
+		end
+
+		-- We should have received all expected targets, and no unexpected
+		-- ones:
+		assert.truthy(set.xor(received_targets, expected_targets):empty());
+	end);
+
+
+	it("works", function ()
+		local expected_targets = set.new({
+			-- xmpp0-a
+			"tcp4  127.0.0.97  5228";
+			"tcp6  fdeb:9619:649e:c7d9::0097  5228";
+			"tcp4  127.0.0.97  5273";
+			"tcp6  fdeb:9619:649e:c7d9::0097  5273";
+
+			-- xmpp0-b
+			"tcp4  127.0.0.98  5274";
+			"tcp6  fdeb:9619:649e:c7d9::0098  5274";
+			"tcp4  127.0.0.98  5216";
+			"tcp6  fdeb:9619:649e:c7d9::0098  5216";
+
+			-- xmpp0-c
+			"tcp4  127.0.0.99  5200";
+			"tcp6  fdeb:9619:649e:c7d9::0099  5200";
+
+			-- xmpp0-d
+			"tcp4  127.0.0.100  5256";
+			"tcp6  fdeb:9619:649e:c7d9::0100  5256";
+
+			-- xmpp2
+			"tcp4  127.0.0.49  5275";
+			"tcp6  fdeb:9619:649e:c7d9::0049  5275";
+
+		});
+		local received_targets = set.new({});
+
+		local r = resolver.new("example.com", "xmpp-server");
+		local done = false;
+		local function handle_target(...)
+			if ... == nil then
+				done = true;
+				-- No more targets
+				return;
+			end
+			received_targets:add(table.concat({ ... }, "  ", 1, 3));
+		end
+		r:next(handle_target);
+		while not done do
+			r:next(handle_target);
+		end
+
+		-- We should have received all expected targets, and no unexpected
+		-- ones:
+		assert.truthy(set.xor(received_targets, expected_targets):empty());
+	end);
+
+	it("balances across weights correctly #slow", function ()
+		-- This mimics many repeated connections to 'example.com' (mock
+		-- records defined above), and records the port number of the
+		-- first target. Therefore it (should) only return priority
+		-- 0 records, and the input data is constructed such that the
+		-- last two digits of the port number represent the percentage
+		-- of times that record should (on average) be picked first.
+
+		-- To prevent random test failures, we test across a handful
+		-- of fixed (randomly selected) seeds.
+		for _, seed in ipairs({ 8401877, 3943829, 7830992 }) do
+			math.randomseed(seed);
+
+			local results = {};
+			local function run()
+				local run_results = {};
+				local r = resolver.new("example.com", "xmpp-server");
+				local function record_target(...)
+					if ... == nil then
+						-- No more targets
+						return;
+					end
+					run_results = { ... };
+				end
+				r:next(record_target);
+				return run_results[3];
+			end
+
+			for _ = 1, 1000 do
+				local port = run();
+				results[port] = (results[port] or 0) + 1;
+			end
+
+			local ports = {};
+			for port in pairs(results) do
+				table.insert(ports, port);
+			end
+			table.sort(ports);
+			for _, port in ipairs(ports) do
+				--print("PORT", port, tostring((results[port]/1000) * 100).."% hits (expected "..tostring(port-5200).."%)");
+				local hit_pct = (results[port]/1000) * 100;
+				local expected_pct = port - 5200;
+				--print(hit_pct, expected_pct, math.abs(hit_pct - expected_pct));
+				assert.is_true(math.abs(hit_pct - expected_pct) < 5);
+			end
+			--print("---");
+		end
+	end);
+end);

--- a/spec/util_poll_spec.lua	Mon Mar 28 11:08:18 2022 +0100
+++ b/spec/util_poll_spec.lua	Mon Mar 28 11:08:53 2022 +0100
@@ -1,6 +1,35 @@
-describe("util.poll", function ()
-	it("loads", function ()
-		require "util.poll"
+describe("util.poll", function()
+	local poll;
+	setup(function()
+		poll = require "util.poll";
+	end);
+	it("loads", function()
+		assert.is_table(poll);
+		assert.is_function(poll.new);
+		assert.is_string(poll.api);
 	end);
+	describe("new", function()
+		local p;
+		setup(function()
+			p = poll.new();
+		end)
+		it("times out", function ()
+			local fd, err = p:wait(0);
+			assert.falsy(fd);
+			assert.equal("timeout", err);
+		end);
+		it("works", function()
+			-- stdout should be writable, right?
+			assert.truthy(p:add(1, false, true));
+			local fd, r, w = p:wait(1);
+			assert.is_number(fd);
+			assert.is_boolean(r);
+			assert.is_boolean(w);
+			assert.equal(1, fd);
+			assert.falsy(r);
+			assert.truthy(w);
+			assert.truthy(p:del(1));
+		end);
+	end)
 end);
 

--- a/spec/util_table_spec.lua	Mon Mar 28 11:08:18 2022 +0100
+++ b/spec/util_table_spec.lua	Mon Mar 28 11:08:53 2022 +0100
@@ -12,6 +12,17 @@
 			assert.same({ "lorem", "ipsum", "dolor", "sit", "amet", n = 5 }, u_table.pack("lorem", "ipsum", "dolor", "sit", "amet"));
 		end);
 	end);
+
+	describe("move()", function ()
+		it("works", function ()
+			local t1 = { "apple", "banana", "carrot" };
+			local t2 = { "cat", "donkey", "elephant" };
+			local t3 = {};
+			u_table.move(t1, 1, 3, 1, t3);
+			u_table.move(t2, 1, 3, 3, t3);
+			assert.same({ "apple", "banana", "cat", "donkey", "elephant" }, t3);
+		end);
+	end);
 end);
 
 

--- a/util-src/table.c	Mon Mar 28 11:08:18 2022 +0100
+++ b/util-src/table.c	Mon Mar 28 11:08:53 2022 +0100
@@ -1,11 +1,21 @@
 #include <lua.h>
 #include <lauxlib.h>
 
+#ifndef LUA_MAXINTEGER
+#include <stdint.h>
+#define LUA_MAXINTEGER PTRDIFF_MAX
+#endif
+
+#if (LUA_VERSION_NUM > 501)
+#define lua_equal(L, A, B) lua_compare(L, A, B, LUA_OPEQ)
+#endif
+
 static int Lcreate_table(lua_State *L) {
 	lua_createtable(L, luaL_checkinteger(L, 1), luaL_checkinteger(L, 2));
 	return 1;
 }
 
+/* COMPAT: w/ Lua pre-5.4 */
 static int Lpack(lua_State *L) {
 	unsigned int n_args = lua_gettop(L);
 	lua_createtable(L, n_args, 1);
@@ -20,6 +30,40 @@
 	return 1;
 }
 
+/* COMPAT: w/ Lua pre-5.4 */
+static int Lmove (lua_State *L) {
+	lua_Integer f = luaL_checkinteger(L, 2);
+	lua_Integer e = luaL_checkinteger(L, 3);
+	lua_Integer t = luaL_checkinteger(L, 4);
+
+	int tt = !lua_isnoneornil(L, 5) ? 5 : 1;  /* destination table */
+	luaL_checktype(L, 1, LUA_TTABLE);
+	luaL_checktype(L, tt, LUA_TTABLE);
+
+	if (e >= f) {  /* otherwise, nothing to move */
+		lua_Integer n, i;
+		luaL_argcheck(L, f > 0 || e < LUA_MAXINTEGER + f, 3,
+		  "too many elements to move");
+		n = e - f + 1;  /* number of elements to move */
+		luaL_argcheck(L, t <= LUA_MAXINTEGER - n + 1, 4,
+		"destination wrap around");
+		if (t > e || t <= f || (tt != 1 && !lua_equal(L, 1, tt))) {
+			for (i = 0; i < n; i++) {
+				lua_rawgeti(L, 1, f + i);
+				lua_rawseti(L, tt, t + i);
+			}
+		} else {
+			for (i = n - 1; i >= 0; i--) {
+				lua_rawgeti(L, 1, f + i);
+				lua_rawseti(L, tt, t + i);
+			}
+		}
+	}
+
+	lua_pushvalue(L, tt);  /* return destination table */
+	return 1;
+}
+
 int luaopen_util_table(lua_State *L) {
 #if (LUA_VERSION_NUM > 501)
 	luaL_checkversion(L);
@@ -29,5 +73,7 @@
 	lua_setfield(L, -2, "create");
 	lua_pushcfunction(L, Lpack);
 	lua_setfield(L, -2, "pack");
+	lua_pushcfunction(L, Lmove);
+	lua_setfield(L, -2, "move");
 	return 1;
 }

--- a/util/array.lua	Mon Mar 28 11:08:18 2022 +0100
+++ b/util/array.lua	Mon Mar 28 11:08:53 2022 +0100
@@ -8,6 +8,7 @@
 
 local t_insert, t_sort, t_remove, t_concat
     = table.insert, table.sort, table.remove, table.concat;
+local t_move = require "util.table".move;
 
 local setmetatable = setmetatable;
 local getmetatable = getmetatable;
@@ -137,13 +138,11 @@
 		return outa;
 	end
 
-	for idx = 1, 1+j-i do
-		outa[idx] = ina[i+(idx-1)];
-	end
+
+	t_move(ina, i, j, 1, outa);
 	if ina == outa then
-		for idx = 2+j-i, #outa do
-			outa[idx] = nil;
-		end
+		-- Clear (nil) remainder of range
+		t_move(ina, #outa+1, #outa*2, 2+j-i, ina);
 	end
 	return outa;
 end
@@ -209,10 +208,7 @@
 end
 
 function array_methods:append(ina)
-	local len, len2 = #self, #ina;
-	for i = 1, len2 do
-		self[len+i] = ina[i];
-	end
+	t_move(ina, 1, #ina, #self+1, self);
 	return self;
 end
 

--- a/util/logger.lua	Mon Mar 28 11:08:18 2022 +0100
+++ b/util/logger.lua	Mon Mar 28 11:08:53 2022 +0100
@@ -10,6 +10,7 @@
 local pairs = pairs;
 local ipairs = ipairs;
 local require = require;
+local t_remove = table.remove;
 
 local _ENV = nil;
 -- luacheck: std none
@@ -78,6 +79,20 @@
 	for _, level in ipairs(levels or {"debug", "info", "warn", "error"}) do
 		add_level_sink(level, sink_function);
 	end
+	return sink_function;
+end
+
+local function remove_sink(sink_function)
+	local removed;
+	for level, sinks in pairs(level_sinks) do
+		for i = #sinks, 1, -1 do
+			if sinks[i] == sink_function then
+				t_remove(sinks, i);
+				removed = true;
+			end
+		end
+	end
+	return removed;
 end
 
 return {
@@ -87,4 +102,5 @@
 	add_level_sink = add_level_sink;
 	add_simple_sink = add_simple_sink;
 	new = make_logger;
+	remove_sink = remove_sink;
 };

--- a/util/prosodyctl/shell.lua	Mon Mar 28 11:08:18 2022 +0100
+++ b/util/prosodyctl/shell.lua	Mon Mar 28 11:08:53 2022 +0100
@@ -89,11 +89,15 @@
 		local errors = 0; -- TODO This is weird, but works for now.
 		client.events.add_handler("received", function(stanza)
 			if stanza.name == "repl-output" or stanza.name == "repl-result" then
+				local dest = io.stdout;
 				if stanza.attr.type == "error" then
 					errors = errors + 1;
-					io.stderr:write(stanza:get_text(), "\n");
+					dest = io.stderr;
+				end
+				if stanza.attr.eol == "0" then
+					dest:write(stanza:get_text());
 				else
-					print(stanza:get_text());
+					dest:write(stanza:get_text(), "\n");
 				end
 			end
 			if stanza.name == "repl-result" then

--- a/util/stanza.lua	Mon Mar 28 11:08:18 2022 +0100
+++ b/util/stanza.lua	Mon Mar 28 11:08:53 2022 +0100
@@ -21,6 +21,8 @@
 local s_gsub        =   string.gsub;
 local s_sub         =    string.sub;
 local s_find        =   string.find;
+local t_move        =    table.move or require "util.table".move;
+local t_create = require"util.table".create;
 
 local valid_utf8 = require "util.encodings".utf8.valid;
 
@@ -275,25 +277,33 @@
 end
 
 local function _clone(stanza, only_top)
-	local attr, tags = {}, {};
+	local attr = {};
 	for k,v in pairs(stanza.attr) do attr[k] = v; end
 	local old_namespaces, namespaces = stanza.namespaces;
 	if old_namespaces then
 		namespaces = {};
 		for k,v in pairs(old_namespaces) do namespaces[k] = v; end
 	end
-	local new = { name = stanza.name, attr = attr, namespaces = namespaces, tags = tags };
+	local tags, new;
+	if only_top then
+		tags = {};
+		new = { name = stanza.name, attr = attr, namespaces = namespaces, tags = tags };
+	else
+		tags = t_create(#stanza.tags, 0);
+		new = t_create(#stanza, 4);
+		new.name = stanza.name;
+		new.attr = attr;
+		new.namespaces = namespaces;
+		new.tags = tags;
+	end
+
+	setmetatable(new, stanza_mt);
 	if not only_top then
-		for i=1,#stanza do
-			local child = stanza[i];
-			if child.name then
-				child = _clone(child);
-				t_insert(tags, child);
-			end
-			t_insert(new, child);
-		end
+		t_move(stanza, 1, #stanza, 1, new);
+		t_move(stanza.tags, 1, #stanza.tags, 1, tags);
+		new:maptags(_clone);
 	end
-	return setmetatable(new, stanza_mt);
+	return new;
 end
 
 local function clone(stanza, only_top)