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-- 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 new_ip = require"util.ip".new_ip;
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};
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