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-rw-r--r--util/rfc6724.lua142
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diff --git a/util/rfc6724.lua b/util/rfc6724.lua
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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};