File

util/rfc6724.lua @ 9089:3a7a0b9f42f3

util.dataforms: Skip all fields for the 'cancel' form type XEP-0004 says: > a data form of type "cancel" SHOULD NOT contain any <field/> elements. The title and instructions don't seem to be of much value in this case either. I'm not aware of 'cancel' being used anywhere, so this should break nothing. Early return is always nice.
author Kim Alvefur <zash@zash.se>
date Fri, 03 Aug 2018 21:06:59 +0200
parent 7259:d8300985f2bb
child 12975:d10957394a3c
line wrap: on
line source

-- Prosody IM
-- Copyright (C) 2011-2013 Florian Zeitz
--
-- This project is MIT/X11 licensed. Please see the
-- COPYING file in the source package for more information.
--

-- This is used to sort destination addresses by preference
-- during S2S connections.
-- We can't hand this off to getaddrinfo, since it blocks

local ip_commonPrefixLength = require"util.ip".commonPrefixLength

local function commonPrefixLength(ipA, ipB)
	local len = ip_commonPrefixLength(ipA, ipB);
	return len < 64 and len or 64;
end

local function t_sort(t, comp)
	for i = 1, (#t - 1) do
		for j = (i + 1), #t do
			local a, b = t[i], t[j];
			if not comp(a,b) then
				t[i], t[j] = b, a;
			end
		end
	end
end

local 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 temporary addresses (over public 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

local function destination(candidates, sources)
	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};