-- Prosody IM -- This file is included with Prosody IM. It has modifications, -- which are hereby placed in the public domain. -- public domain 20080404 lua@ztact.com -- todo: quick (default) header generation -- todo: nxdomain, error handling -- todo: cache results of encodeName -- reference: http://tools.ietf.org/html/rfc1035 -- reference: http://tools.ietf.org/html/rfc1876 (LOC) local socket = require "socket"; local ztact = require "util.ztact"; local _, windows = pcall(require, "util.windows"); local is_windows = (_ and windows) or os.getenv("WINDIR"); local coroutine, io, math, string, table = coroutine, io, math, string, table; local ipairs, next, pairs, print, setmetatable, tostring, assert, error, unpack = ipairs, next, pairs, print, setmetatable, tostring, assert, error, unpack; local get, set = ztact.get, ztact.set; -------------------------------------------------- module dns module('dns') local dns = _M; -- dns type & class codes ------------------------------ dns type & class codes local append = table.insert local function highbyte(i) -- - - - - - - - - - - - - - - - - - - highbyte return (i-(i%0x100))/0x100; end local function augment (t) -- - - - - - - - - - - - - - - - - - - - augment local a = {}; for i,s in pairs(t) do a[i] = s; a[s] = s; a[string.lower(s)] = s; end return a; end local function encode (t) -- - - - - - - - - - - - - - - - - - - - - encode local code = {}; for i,s in pairs(t) do local word = string.char(highbyte(i), i%0x100); code[i] = word; code[s] = word; code[string.lower(s)] = word; end return code; end dns.types = { 'A', 'NS', 'MD', 'MF', 'CNAME', 'SOA', 'MB', 'MG', 'MR', 'NULL', 'WKS', 'PTR', 'HINFO', 'MINFO', 'MX', 'TXT', [ 28] = 'AAAA', [ 29] = 'LOC', [ 33] = 'SRV', [252] = 'AXFR', [253] = 'MAILB', [254] = 'MAILA', [255] = '*' }; dns.classes = { 'IN', 'CS', 'CH', 'HS', [255] = '*' }; dns.type = augment (dns.types); dns.class = augment (dns.classes); dns.typecode = encode (dns.types); dns.classcode = encode (dns.classes); local function standardize(qname, qtype, qclass) -- - - - - - - standardize if string.byte(qname, -1) ~= 0x2E then qname = qname..'.'; end qname = string.lower(qname); return qname, dns.type[qtype or 'A'], dns.class[qclass or 'IN']; end local function prune(rrs, time, soft) -- - - - - - - - - - - - - - - prune time = time or socket.gettime(); for i,rr in pairs(rrs) do if rr.tod then -- rr.tod = rr.tod - 50 -- accelerated decripitude rr.ttl = math.floor(rr.tod - time); if rr.ttl <= 0 then table.remove(rrs, i); return prune(rrs, time, soft); -- Re-iterate end elseif soft == 'soft' then -- What is this? I forget! assert(rr.ttl == 0); rrs[i] = nil; end end end -- metatables & co. ------------------------------------------ metatables & co. local resolver = {}; resolver.__index = resolver; local SRV_tostring; local rr_metatable = {}; -- - - - - - - - - - - - - - - - - - - rr_metatable function rr_metatable.__tostring(rr) local s0 = string.format('%2s %-5s %6i %-28s', rr.class, rr.type, rr.ttl, rr.name); local s1 = ''; if rr.type == 'A' then s1 = ' '..rr.a; elseif rr.type == 'MX' then s1 = string.format(' %2i %s', rr.pref, rr.mx); elseif rr.type == 'CNAME' then s1 = ' '..rr.cname; elseif rr.type == 'LOC' then s1 = ' '..resolver.LOC_tostring(rr); elseif rr.type == 'NS' then s1 = ' '..rr.ns; elseif rr.type == 'SRV' then s1 = ' '..SRV_tostring(rr); elseif rr.type == 'TXT' then s1 = ' '..rr.txt; else s1 = ' '; end return s0..s1; end local rrs_metatable = {}; -- - - - - - - - - - - - - - - - - - rrs_metatable function rrs_metatable.__tostring(rrs) local t = {}; for i,rr in pairs(rrs) do append(t, tostring(rr)..'\n'); end return table.concat(t); end local cache_metatable = {}; -- - - - - - - - - - - - - - - - cache_metatable function cache_metatable.__tostring(cache) local time = socket.gettime(); local t = {}; for class,types in pairs(cache) do for type,names in pairs(types) do for name,rrs in pairs(names) do prune(rrs, time); append(t, tostring(rrs)); end end end return table.concat(t); end function resolver:new() -- - - - - - - - - - - - - - - - - - - - - resolver local r = { active = {}, cache = {}, unsorted = {} }; setmetatable(r, resolver); setmetatable(r.cache, cache_metatable); setmetatable(r.unsorted, { __mode = 'kv' }); return r; end -- packet layer -------------------------------------------------- packet layer function dns.random(...) -- - - - - - - - - - - - - - - - - - - dns.random math.randomseed(math.floor(10000*socket.gettime())); dns.random = math.random; return dns.random(...); end local function encodeHeader(o) -- - - - - - - - - - - - - - - encodeHeader o = o or {}; o.id = o.id or dns.random(0, 0xffff); -- 16b (random) id o.rd = o.rd or 1; -- 1b 1 recursion desired o.tc = o.tc or 0; -- 1b 1 truncated response o.aa = o.aa or 0; -- 1b 1 authoritative response o.opcode = o.opcode or 0; -- 4b 0 query -- 1 inverse query -- 2 server status request -- 3-15 reserved o.qr = o.qr or 0; -- 1b 0 query, 1 response o.rcode = o.rcode or 0; -- 4b 0 no error -- 1 format error -- 2 server failure -- 3 name error -- 4 not implemented -- 5 refused -- 6-15 reserved o.z = o.z or 0; -- 3b 0 resvered o.ra = o.ra or 0; -- 1b 1 recursion available o.qdcount = o.qdcount or 1; -- 16b number of question RRs o.ancount = o.ancount or 0; -- 16b number of answers RRs o.nscount = o.nscount or 0; -- 16b number of nameservers RRs o.arcount = o.arcount or 0; -- 16b number of additional RRs -- string.char() rounds, so prevent roundup with -0.4999 local header = string.char( highbyte(o.id), o.id %0x100, o.rd + 2*o.tc + 4*o.aa + 8*o.opcode + 128*o.qr, o.rcode + 16*o.z + 128*o.ra, highbyte(o.qdcount), o.qdcount %0x100, highbyte(o.ancount), o.ancount %0x100, highbyte(o.nscount), o.nscount %0x100, highbyte(o.arcount), o.arcount %0x100 ); return header, o.id; end local function encodeName(name) -- - - - - - - - - - - - - - - - encodeName local t = {}; for part in string.gmatch(name, '[^.]+') do append(t, string.char(string.len(part))); append(t, part); end append(t, string.char(0)); return table.concat(t); end local function encodeQuestion(qname, qtype, qclass) -- - - - encodeQuestion qname = encodeName(qname); qtype = dns.typecode[qtype or 'a']; qclass = dns.classcode[qclass or 'in']; return qname..qtype..qclass; end function resolver:byte(len) -- - - - - - - - - - - - - - - - - - - - - byte len = len or 1; local offset = self.offset; local last = offset + len - 1; if last > #self.packet then error(string.format('out of bounds: %i>%i', last, #self.packet)); end self.offset = offset + len; return string.byte(self.packet, offset, last); end function resolver:word() -- - - - - - - - - - - - - - - - - - - - - - word local b1, b2 = self:byte(2); return 0x100*b1 + b2; end function resolver:dword () -- - - - - - - - - - - - - - - - - - - - - dword local b1, b2, b3, b4 = self:byte(4); --print('dword', b1, b2, b3, b4); return 0x1000000*b1 + 0x10000*b2 + 0x100*b3 + b4; end function resolver:sub(len) -- - - - - - - - - - - - - - - - - - - - - - sub len = len or 1; local s = string.sub(self.packet, self.offset, self.offset + len - 1); self.offset = self.offset + len; return s; end function resolver:header(force) -- - - - - - - - - - - - - - - - - - header local id = self:word(); --print(string.format(':header id %x', id)); if not self.active[id] and not force then return nil; end local h = { id = id }; local b1, b2 = self:byte(2); h.rd = b1 %2; h.tc = b1 /2%2; h.aa = b1 /4%2; h.opcode = b1 /8%16; h.qr = b1 /128; h.rcode = b2 %16; h.z = b2 /16%8; h.ra = b2 /128; h.qdcount = self:word(); h.ancount = self:word(); h.nscount = self:word(); h.arcount = self:word(); for k,v in pairs(h) do h[k] = v-v%1; end return h; end function resolver:name() -- - - - - - - - - - - - - - - - - - - - - - name local remember, pointers = nil, 0; local len = self:byte(); local n = {}; while len > 0 do if len >= 0xc0 then -- name is "compressed" pointers = pointers + 1; if pointers >= 20 then error('dns error: 20 pointers'); end; local offset = ((len-0xc0)*0x100) + self:byte(); remember = remember or self.offset; self.offset = offset + 1; -- +1 for lua else -- name is not compressed append(n, self:sub(len)..'.'); end len = self:byte(); end self.offset = remember or self.offset; return table.concat(n); end function resolver:question() -- - - - - - - - - - - - - - - - - - question local q = {}; q.name = self:name(); q.type = dns.type[self:word()]; q.class = dns.class[self:word()]; return q; end function resolver:A(rr) -- - - - - - - - - - - - - - - - - - - - - - - - A local b1, b2, b3, b4 = self:byte(4); rr.a = string.format('%i.%i.%i.%i', b1, b2, b3, b4); end function resolver:CNAME(rr) -- - - - - - - - - - - - - - - - - - - - CNAME rr.cname = self:name(); end function resolver:MX(rr) -- - - - - - - - - - - - - - - - - - - - - - - MX rr.pref = self:word(); rr.mx = self:name(); end function resolver:LOC_nibble_power() -- - - - - - - - - - LOC_nibble_power local b = self:byte(); --print('nibbles', ((b-(b%0x10))/0x10), (b%0x10)); return ((b-(b%0x10))/0x10) * (10^(b%0x10)); end function resolver:LOC(rr) -- - - - - - - - - - - - - - - - - - - - - - LOC rr.version = self:byte(); if rr.version == 0 then rr.loc = rr.loc or {}; rr.loc.size = self:LOC_nibble_power(); rr.loc.horiz_pre = self:LOC_nibble_power(); rr.loc.vert_pre = self:LOC_nibble_power(); rr.loc.latitude = self:dword(); rr.loc.longitude = self:dword(); rr.loc.altitude = self:dword(); end end local function LOC_tostring_degrees(f, pos, neg) -- - - - - - - - - - - - - f = f - 0x80000000; if f < 0 then pos = neg; f = -f; end local deg, min, msec; msec = f%60000; f = (f-msec)/60000; min = f%60; deg = (f-min)/60; return string.format('%3d %2d %2.3f %s', deg, min, msec/1000, pos); end function resolver.LOC_tostring(rr) -- - - - - - - - - - - - - LOC_tostring local t = {}; --[[ for k,name in pairs { 'size', 'horiz_pre', 'vert_pre', 'latitude', 'longitude', 'altitude' } do append(t, string.format('%4s%-10s: %12.0f\n', '', name, rr.loc[name])); end --]] append(t, string.format( '%s %s %.2fm %.2fm %.2fm %.2fm', LOC_tostring_degrees (rr.loc.latitude, 'N', 'S'), LOC_tostring_degrees (rr.loc.longitude, 'E', 'W'), (rr.loc.altitude - 10000000) / 100, rr.loc.size / 100, rr.loc.horiz_pre / 100, rr.loc.vert_pre / 100 )); return table.concat(t); end function resolver:NS(rr) -- - - - - - - - - - - - - - - - - - - - - - - NS rr.ns = self:name(); end function resolver:SOA(rr) -- - - - - - - - - - - - - - - - - - - - - - SOA end function resolver:SRV(rr) -- - - - - - - - - - - - - - - - - - - - - - SRV rr.srv = {}; rr.srv.priority = self:word(); rr.srv.weight = self:word(); rr.srv.port = self:word(); rr.srv.target = self:name(); end function SRV_tostring(rr) -- - - - - - - - - - - - - - - - - - SRV_tostring local s = rr.srv; return string.format( '%5d %5d %5d %s', s.priority, s.weight, s.port, s.target ); end function resolver:TXT(rr) -- - - - - - - - - - - - - - - - - - - - - - TXT rr.txt = self:sub (rr.rdlength); end function resolver:rr() -- - - - - - - - - - - - - - - - - - - - - - - - rr local rr = {}; setmetatable(rr, rr_metatable); rr.name = self:name(self); rr.type = dns.type[self:word()] or rr.type; rr.class = dns.class[self:word()] or rr.class; rr.ttl = 0x10000*self:word() + self:word(); rr.rdlength = self:word(); if rr.ttl <= 0 then rr.tod = self.time + 30; else rr.tod = self.time + rr.ttl; end local remember = self.offset; local rr_parser = self[dns.type[rr.type]]; if rr_parser then rr_parser(self, rr); end self.offset = remember; rr.rdata = self:sub(rr.rdlength); return rr; end function resolver:rrs (count) -- - - - - - - - - - - - - - - - - - - - - rrs local rrs = {}; for i = 1,count do append(rrs, self:rr()); end return rrs; end function resolver:decode(packet, force) -- - - - - - - - - - - - - - decode self.packet, self.offset = packet, 1; local header = self:header(force); if not header then return nil; end local response = { header = header }; response.question = {}; local offset = self.offset; for i = 1,response.header.qdcount do append(response.question, self:question()); end response.question.raw = string.sub(self.packet, offset, self.offset - 1); if not force then if not self.active[response.header.id] or not self.active[response.header.id][response.question.raw] then return nil; end end response.answer = self:rrs(response.header.ancount); response.authority = self:rrs(response.header.nscount); response.additional = self:rrs(response.header.arcount); return response; end -- socket layer -------------------------------------------------- socket layer resolver.delays = { 1, 3 }; function resolver:addnameserver(address) -- - - - - - - - - - addnameserver self.server = self.server or {}; append(self.server, address); end function resolver:setnameserver(address) -- - - - - - - - - - setnameserver self.server = {}; self:addnameserver(address); end function resolver:adddefaultnameservers() -- - - - - adddefaultnameservers if is_windows then if windows then for _, server in ipairs(windows.get_nameservers()) do self:addnameserver(server); end end if not self.server or #self.server == 0 then -- TODO log warning about no nameservers, adding opendns servers as fallback self:addnameserver("208.67.222.222"); self:addnameserver("208.67.220.220") ; end else -- posix local resolv_conf = io.open("/etc/resolv.conf"); if resolv_conf then for line in resolv_conf:lines() do line = line:gsub("#.*$", "") :match('^%s*nameserver%s+(.*)%s*$'); if line then line:gsub("%f[%d.](%d+%.%d+%.%d+%.%d+)%f[^%d.]", function (address) self:addnameserver(address) end); end end end if not self.server or #self.server == 0 then -- TODO log warning about no nameservers, adding localhost as the default nameserver self:addnameserver("127.0.0.1"); end end end function resolver:getsocket(servernum) -- - - - - - - - - - - - - getsocket self.socket = self.socket or {}; self.socketset = self.socketset or {}; local sock = self.socket[servernum]; if sock then return sock; end sock = socket.udp(); if self.socket_wrapper then sock = self.socket_wrapper(sock, self); end sock:settimeout(0); -- todo: attempt to use a random port, fallback to 0 sock:setsockname('*', 0); sock:setpeername(self.server[servernum], 53); self.socket[servernum] = sock; self.socketset[sock] = servernum; return sock; end function resolver:voidsocket(sock) if self.socket[sock] then self.socketset[self.socket[sock]] = nil; self.socket[sock] = nil; elseif self.socketset[sock] then self.socket[self.socketset[sock]] = nil; self.socketset[sock] = nil; end end function resolver:socket_wrapper_set(func) -- - - - - - - socket_wrapper_set self.socket_wrapper = func; end function resolver:closeall () -- - - - - - - - - - - - - - - - - - closeall for i,sock in ipairs(self.socket) do self.socket[i] = nil; self.socketset[sock] = nil; sock:close(); end end function resolver:remember(rr, type) -- - - - - - - - - - - - - - remember --print ('remember', type, rr.class, rr.type, rr.name) local qname, qtype, qclass = standardize(rr.name, rr.type, rr.class); if type ~= '*' then type = qtype; local all = get(self.cache, qclass, '*', qname); --print('remember all', all); if all then append(all, rr); end end self.cache = self.cache or setmetatable({}, cache_metatable); local rrs = get(self.cache, qclass, type, qname) or set(self.cache, qclass, type, qname, setmetatable({}, rrs_metatable)); append(rrs, rr); if type == 'MX' then self.unsorted[rrs] = true; end end local function comp_mx(a, b) -- - - - - - - - - - - - - - - - - - - comp_mx return (a.pref == b.pref) and (a.mx < b.mx) or (a.pref < b.pref); end function resolver:peek (qname, qtype, qclass) -- - - - - - - - - - - - peek qname, qtype, qclass = standardize(qname, qtype, qclass); local rrs = get(self.cache, qclass, qtype, qname); if not rrs then return nil; end if prune(rrs, socket.gettime()) and qtype == '*' or not next(rrs) then set(self.cache, qclass, qtype, qname, nil); return nil; end if self.unsorted[rrs] then table.sort (rrs, comp_mx); end return rrs; end function resolver:purge(soft) -- - - - - - - - - - - - - - - - - - - purge if soft == 'soft' then self.time = socket.gettime(); for class,types in pairs(self.cache or {}) do for type,names in pairs(types) do for name,rrs in pairs(names) do prune(rrs, self.time, 'soft') end end end else self.cache = {}; end end function resolver:query(qname, qtype, qclass) -- - - - - - - - - - -- query qname, qtype, qclass = standardize(qname, qtype, qclass) if not self.server then self:adddefaultnameservers(); end local question = encodeQuestion(qname, qtype, qclass); local peek = self:peek (qname, qtype, qclass); if peek then return peek; end local header, id = encodeHeader(); --print ('query id', id, qclass, qtype, qname) local o = { packet = header..question, server = self.best_server, delay = 1, retry = socket.gettime() + self.delays[1] }; -- remember the query self.active[id] = self.active[id] or {}; self.active[id][question] = o; -- remember which coroutine wants the answer local co = coroutine.running(); if co then set(self.wanted, qclass, qtype, qname, co, true); --set(self.yielded, co, qclass, qtype, qname, true); end self:getsocket (o.server):send (o.packet) end function resolver:servfail(sock) -- Resend all queries for this server local num = self.socketset[sock] -- Socket is dead now self:voidsocket(sock); -- Find all requests to the down server, and retry on the next server self.time = socket.gettime(); for id,queries in pairs(self.active) do for question,o in pairs(queries) do if o.server == num then -- This request was to the broken server o.server = o.server + 1 -- Use next server if o.server > #self.server then o.server = 1; end o.retries = (o.retries or 0) + 1; if o.retries >= #self.server then --print('timeout'); queries[question] = nil; else local _a = self:getsocket(o.server); if _a then _a:send(o.packet); end end end end end if num == self.best_server then self.best_server = self.best_server + 1; if self.best_server > #self.server then -- Exhausted all servers, try first again self.best_server = 1; end end end function resolver:receive(rset) -- - - - - - - - - - - - - - - - - receive --print('receive'); print(self.socket); self.time = socket.gettime(); rset = rset or self.socket; local response; for i,sock in pairs(rset) do if self.socketset[sock] then local packet = sock:receive(); if packet then response = self:decode(packet); if response and self.active[response.header.id] and self.active[response.header.id][response.question.raw] then --print('received response'); --self.print(response); for j,rr in pairs(response.answer) do if rr.name:sub(-#response.question[1].name, -1) == response.question[1].name then self:remember(rr, response.question[1].type) end end -- retire the query local queries = self.active[response.header.id]; queries[response.question.raw] = nil; if not next(queries) then self.active[response.header.id] = nil; end if not next(self.active) then self:closeall(); end -- was the query on the wanted list? local q = response.question[1]; local cos = get(self.wanted, q.class, q.type, q.name); if cos then for co in pairs(cos) do set(self.yielded, co, q.class, q.type, q.name, nil); if coroutine.status(co) == "suspended" then coroutine.resume(co); end end set(self.wanted, q.class, q.type, q.name, nil); end end end end end return response; end function resolver:feed(sock, packet) --print('receive'); print(self.socket); self.time = socket.gettime(); local response = self:decode(packet); if response and self.active[response.header.id] and self.active[response.header.id][response.question.raw] then --print('received response'); --self.print(response); for j,rr in pairs(response.answer) do self:remember(rr, response.question[1].type); end -- retire the query local queries = self.active[response.header.id]; queries[response.question.raw] = nil; if not next(queries) then self.active[response.header.id] = nil; end if not next(self.active) then self:closeall(); end -- was the query on the wanted list? local q = response.question[1]; if q then local cos = get(self.wanted, q.class, q.type, q.name); if cos then for co in pairs(cos) do set(self.yielded, co, q.class, q.type, q.name, nil); if coroutine.status(co) == "suspended" then coroutine.resume(co); end end set(self.wanted, q.class, q.type, q.name, nil); end end end return response; end function resolver:cancel(data) local cos = get(self.wanted, unpack(data, 1, 3)); if cos then cos[data[4]] = nil; end end function resolver:pulse() -- - - - - - - - - - - - - - - - - - - - - pulse --print(':pulse'); while self:receive() do end if not next(self.active) then return nil; end self.time = socket.gettime(); for id,queries in pairs(self.active) do for question,o in pairs(queries) do if self.time >= o.retry then o.server = o.server + 1; if o.server > #self.server then o.server = 1; o.delay = o.delay + 1; end if o.delay > #self.delays then --print('timeout'); queries[question] = nil; if not next(queries) then self.active[id] = nil; end if not next(self.active) then return nil; end else --print('retry', o.server, o.delay); local _a = self.socket[o.server]; if _a then _a:send(o.packet); end o.retry = self.time + self.delays[o.delay]; end end end end if next(self.active) then return true; end return nil; end function resolver:lookup(qname, qtype, qclass) -- - - - - - - - - - lookup self:query (qname, qtype, qclass) while self:pulse() do socket.select(self.socket, nil, 4); end --print(self.cache); return self:peek(qname, qtype, qclass); end function resolver:lookupex(handler, qname, qtype, qclass) -- - - - - - - - - - lookup return self:peek(qname, qtype, qclass) or self:query(qname, qtype, qclass); end --print ---------------------------------------------------------------- print local hints = { -- - - - - - - - - - - - - - - - - - - - - - - - - - - hints qr = { [0]='query', 'response' }, opcode = { [0]='query', 'inverse query', 'server status request' }, aa = { [0]='non-authoritative', 'authoritative' }, tc = { [0]='complete', 'truncated' }, rd = { [0]='recursion not desired', 'recursion desired' }, ra = { [0]='recursion not available', 'recursion available' }, z = { [0]='(reserved)' }, rcode = { [0]='no error', 'format error', 'server failure', 'name error', 'not implemented' }, type = dns.type, class = dns.class }; local function hint(p, s) -- - - - - - - - - - - - - - - - - - - - - - hint return (hints[s] and hints[s][p[s]]) or ''; end function resolver.print(response) -- - - - - - - - - - - - - resolver.print for s,s in pairs { 'id', 'qr', 'opcode', 'aa', 'tc', 'rd', 'ra', 'z', 'rcode', 'qdcount', 'ancount', 'nscount', 'arcount' } do print( string.format('%-30s', 'header.'..s), response.header[s], hint(response.header, s) ); end for i,question in ipairs(response.question) do print(string.format ('question[%i].name ', i), question.name); print(string.format ('question[%i].type ', i), question.type); print(string.format ('question[%i].class ', i), question.class); end local common = { name=1, type=1, class=1, ttl=1, rdlength=1, rdata=1 }; local tmp; for s,s in pairs({'answer', 'authority', 'additional'}) do for i,rr in pairs(response[s]) do for j,t in pairs({ 'name', 'type', 'class', 'ttl', 'rdlength' }) do tmp = string.format('%s[%i].%s', s, i, t); print(string.format('%-30s', tmp), rr[t], hint(rr, t)); end for j,t in pairs(rr) do if not common[j] then tmp = string.format('%s[%i].%s', s, i, j); print(string.format('%-30s %s', tostring(tmp), tostring(t))); end end end end end -- module api ------------------------------------------------------ module api function dns.resolver () -- - - - - - - - - - - - - - - - - - - - - resolver -- this function seems to be redundant with resolver.new () local r = { active = {}, cache = {}, unsorted = {}, wanted = {}, yielded = {}, best_server = 1 }; setmetatable (r, resolver); setmetatable (r.cache, cache_metatable); setmetatable (r.unsorted, { __mode = 'kv' }); return r; end local _resolver = dns.resolver(); dns._resolver = _resolver; function dns.lookup(...) -- - - - - - - - - - - - - - - - - - - - - lookup return _resolver:lookup(...); end function dns.purge(...) -- - - - - - - - - - - - - - - - - - - - - - purge return _resolver:purge(...); end function dns.peek(...) -- - - - - - - - - - - - - - - - - - - - - - - peek return _resolver:peek(...); end function dns.query(...) -- - - - - - - - - - - - - - - - - - - - - - query return _resolver:query(...); end function dns.feed(...) -- - - - - - - - - - - - - - - - - - - - - - - feed return _resolver:feed(...); end function dns.cancel(...) -- - - - - - - - - - - - - - - - - - - - - - cancel return _resolver:cancel(...); end function dns.socket_wrapper_set(...) -- - - - - - - - - socket_wrapper_set return _resolver:socket_wrapper_set(...); end return dns;