--- a/tests/test.lua	Sat Oct 22 17:51:53 2011 +0200
+++ b/tests/test.lua	Sat Oct 22 17:59:33 2011 +0200
@@ -12,6 +12,7 @@
 	package.loaded["net.connlisteners"] = { get = function () return {} end };
 	dotest "util.jid"
 	dotest "util.multitable"
+	dotest "util.rfc3484"
 	dotest "net.http"
 	dotest "core.modulemanager"
 	dotest "core.stanza_router"

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tests/test_util_rfc3484.lua	Sat Oct 22 17:59:33 2011 +0200
@@ -0,0 +1,51 @@
+-- Prosody IM
+-- Copyright (C) 2011 Florian Zeitz
+--
+-- This project is MIT/X11 licensed. Please see the
+-- COPYING file in the source package for more information.
+--
+
+function source(source)
+	local new_ip = require"util.ip".new_ip;
+	assert_equal(source(new_ip("2001::1", "IPv6"), {new_ip("3ffe::1", "IPv6"), new_ip("fe80::1", "IPv6")}).addr, "3ffe::1", "prefer appropriate scope");
+	assert_equal(source(new_ip("2001::1", "IPv6"), {new_ip("fe80::1", "IPv6"), new_ip("fec0::1", "IPv6")}).addr, "fec0::1", "prefer appropriate scope");
+	assert_equal(source(new_ip("fec0::1", "IPv6"), {new_ip("fe80::1", "IPv6"), new_ip("2001::1", "IPv6")}).addr, "2001::1", "prefer appropriate scope");
+	assert_equal(source(new_ip("ff05::1", "IPv6"), {new_ip("fe80::1", "IPv6"), new_ip("fec0::1", "IPv6"), new_ip("2001::1", "IPv6")}).addr, "fec0::1", "prefer appropriate scope");
+	assert_equal(source(new_ip("2001::1", "IPv6"), {new_ip("2001::1", "IPv6"), new_ip("2002::1", "IPv6")}).addr, "2001::1", "prefer same address");
+	assert_equal(source(new_ip("fec0::1", "IPv6"), {new_ip("fec0::2", "IPv6"), new_ip("2001::1", "IPv6")}).addr, "fec0::2", "prefer appropriate scope");
+	assert_equal(source(new_ip("2001::1", "IPv6"), {new_ip("2001::2", "IPv6"), new_ip("3ffe::2", "IPv6")}).addr, "2001::2", "longest matching prefix");
+	assert_equal(source(new_ip("2002:836b:2179::1", "IPv6"), {new_ip("2002:836b:2179::d5e3:7953:13eb:22e8", "IPv6"), new_ip("2001::2", "IPv6")}).addr, "2002:836b:2179::d5e3:7953:13eb:22e8", "prefer matching label");
+end
+
+function destination(dest)
+	local order;
+	local new_ip = require"util.ip".new_ip;
+	order = dest({new_ip("2001::1", "IPv6"), new_ip("131.107.65.121", "IPv4")}, {new_ip("2001::2", "IPv6"), new_ip("fe80::1", "IPv6"), new_ip("169.254.13.78", "IPv4")})
+	assert_equal(order[1].addr, "2001::1", "prefer matching scope");
+	assert_equal(order[2].addr, "131.107.65.121", "prefer matching scope")
+
+	order = dest({new_ip("2001::1", "IPv6"), new_ip("131.107.65.121", "IPv4")}, {new_ip("fe80::1", "IPv6"), new_ip("131.107.65.117", "IPv4")})
+	assert_equal(order[1].addr, "131.107.65.121", "prefer matching scope")
+	assert_equal(order[2].addr, "2001::1", "prefer matching scope")
+
+	order = dest({new_ip("2001::1", "IPv6"), new_ip("10.1.2.3", "IPv4")}, {new_ip("2001::2", "IPv6"), new_ip("fe80::1", "IPv6"), new_ip("10.1.2.4", "IPv4")})
+	assert_equal(order[1].addr, "2001::1", "prefer higher precedence");
+	assert_equal(order[2].addr, "10.1.2.3", "prefer higher precedence");
+
+	order = dest({new_ip("2001::1", "IPv6"), new_ip("fec0::1", "IPv6"), new_ip("fe80::1", "IPv6")}, {new_ip("2001::2", "IPv6"), new_ip("fec0::1", "IPv6"), new_ip("fe80::2", "IPv6")})
+	assert_equal(order[1].addr, "fe80::1", "prefer smaller scope");
+	assert_equal(order[2].addr, "fec0::1", "prefer smaller scope");
+	assert_equal(order[3].addr, "2001::1", "prefer smaller scope");
+
+	order = dest({new_ip("2001::1", "IPv6"), new_ip("3ffe::1", "IPv6")}, {new_ip("2001::2", "IPv6"), new_ip("3f44::2", "IPv6"), new_ip("fe80::2", "IPv6")})
+	assert_equal(order[1].addr, "2001::1", "longest matching prefix");
+	assert_equal(order[2].addr, "3ffe::1", "longest matching prefix");
+
+	order = dest({new_ip("2002:836b:4179::1", "IPv6"), new_ip("2001::1", "IPv6")}, {new_ip("2002:836b:4179::2", "IPv6"), new_ip("fe80::2", "IPv6")})
+	assert_equal(order[1].addr, "2002:836b:4179::1", "prefer matching label");
+	assert_equal(order[2].addr, "2001::1", "prefer matching label");
+
+	order = dest({new_ip("2002:836b:4179::1", "IPv6"), new_ip("2001::1", "IPv6")}, {new_ip("2002:836b:4179::2", "IPv6"), new_ip("2001::2", "IPv6"), new_ip("fe80::2", "IPv6")})
+	assert_equal(order[1].addr, "2001::1", "prefer higher precedence");
+	assert_equal(order[2].addr, "2002:836b:4179::1", "prefer higher precedence");
+end

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/util/rfc3484.lua	Sat Oct 22 17:59:33 2011 +0200
@@ -0,0 +1,124 @@
+-- Prosody IM
+-- Copyright (C) 2008-2011 Florian Zeitz
+--
+-- This project is MIT/X11 licensed. Please see the
+-- COPYING file in the source package for more information.
+--
+
+local t_sort = table.sort;
+local commonPrefixLength = require"util.ip".commonPrefixLength
+local new_ip = require"util.ip".new_ip;
+
+function source(dest, candidates)
+	local function comp(ipA, ipB)
+		-- Rule 1: Prefer same address
+		if dest == ipA then
+			return true;
+		elseif dest == ipB then
+			return false;
+		end
+
+		-- Rule 2: Prefer appropriate scope
+		if ipA.scope < ipB.scope then
+			if ipA.scope < dest.scope then
+				return false;
+			else
+				return true;
+			end
+		elseif ipA.scope > ipB.scope then
+			if ipB.scope < dest.scope then
+				return true;
+			else
+				return false;
+			end
+		end
+
+		-- Rule 3: Avoid deprecated addresses
+		-- XXX: No way to determine this
+		-- Rule 4: Prefer home addresses
+		-- XXX: Mobility Address related, no way to determine this
+		-- Rule 5: Prefer outgoing interface
+		-- XXX: Interface to address relation. No way to determine this
+		-- Rule 6: Prefer matching label
+		if ipA.label == dest.label and ipB.label ~= dest.label then
+			return true;
+		elseif ipB.label == dest.label and ipA.label ~= dest.label then
+			return false;
+		end
+
+		-- Rule 7: Prefer public addresses (over temporary ones)
+		-- XXX: No way to determine this
+		-- Rule 8: Use longest matching prefix
+		if commonPrefixLength(ipA, dest) > commonPrefixLength(ipB, dest) then
+			return true;
+		else
+			return false;
+		end
+	end
+
+	t_sort(candidates, comp);
+	return candidates[1];
+end
+
+function destination(candidates, sources)
+	local t_sort = table.sort;
+	local sourceAddrs = {};
+	local function comp(ipA, ipB)
+		local ipAsource = sourceAddrs[ipA];
+		local ipBsource = sourceAddrs[ipB];
+		-- Rule 1: Avoid unusable destinations
+		-- XXX: No such information
+		-- Rule 2: Prefer matching scope
+		if ipA.scope == ipAsource.scope and ipB.scope ~= ipBsource.scope then
+			return true;
+		elseif ipA.scope ~= ipAsource.scope and ipB.scope == ipBsource.scope then
+			return false;
+		end
+
+		-- Rule 3: Avoid deprecated addresses
+		-- XXX: No way to determine this
+		-- Rule 4: Prefer home addresses
+		-- XXX: Mobility Address related, no way to determine this
+		-- Rule 5: Prefer matching label
+		if ipAsource.label == ipA.label and ipBsource.label ~= ipB.label then
+			return true;
+		elseif ipBsource.label == ipB.label and ipAsource.label ~= ipA.label then
+			return false;
+		end
+
+		-- Rule 6: Prefer higher precedence
+		if ipA.precedence > ipB.precedence then
+			return true;
+		elseif ipA.precedence < ipB.precedence then
+			return false;
+		end
+
+		-- Rule 7: Prefer native transport
+		-- XXX: No way to determine this
+		-- Rule 8: Prefer smaller scope
+		if ipA.scope < ipB.scope then
+			return true;
+		elseif ipA.scope > ipB.scope then
+			return false;
+		end
+
+		-- Rule 9: Use longest matching prefix
+		if commonPrefixLength(ipA, ipAsource) > commonPrefixLength(ipB, ipBsource) then
+			return true;
+		elseif commonPrefixLength(ipA, ipAsource) < commonPrefixLength(ipB, ipBsource) then
+			return false;
+		end
+
+		-- Rule 10: Otherwise, leave order unchanged
+		return true;
+	end
+	for _, ip in ipairs(candidates) do
+		sourceAddrs[ip] = source(ip, sources);
+	end
+
+	t_sort(candidates, comp);
+	return candidates;
+end
+
+return {source = source,
+	destination = destination};