2 -- This file is included with Prosody IM. It has modifications,
3 -- which are hereby placed in the public domain.
6 -- todo: quick (default) header generation
7 -- todo: nxdomain, error handling
8 -- todo: cache results of encodeName
11 -- reference: http://tools.ietf.org/html/rfc1035
12 -- reference: http://tools.ietf.org/html/rfc1876 (LOC)
15 local socket = require "socket";
16 local timer = require "util.timer";
18 local _, windows = pcall(require, "util.windows");
19 local is_windows = (_ and windows) or os.getenv("WINDIR");
21 local coroutine, io, math, string, table =
22 coroutine, io, math, string, table;
24 local ipairs, next, pairs, print, setmetatable, tostring, assert, error, unpack, select, type=
25 ipairs, next, pairs, print, setmetatable, tostring, assert, error, unpack, select, type;
27 local ztact = { -- public domain 20080404 lua@ztact.com
28 get = function(parent, ...)
29 local len = select('#', ...);
31 parent = parent[select(i, ...)];
32 if parent == nil then break; end
36 set = function(parent, ...)
37 local len = select('#', ...);
38 local key, value = select(len-1, ...);
39 local cutpoint, cutkey;
42 local key = select (i, ...)
43 local child = parent[key]
48 elseif next(child, next(child)) then
49 cutpoint = nil; cutkey = nil;
50 elseif cutpoint == nil then
51 cutpoint = parent; cutkey = key;
53 elseif child == nil then
60 if value == nil and cutpoint then
61 cutpoint[cutkey] = nil;
68 local get, set = ztact.get, ztact.set;
70 local default_timeout = 15;
72 -------------------------------------------------- module dns
77 -- dns type & class codes ------------------------------ dns type & class codes
80 local append = table.insert
83 local function highbyte(i) -- - - - - - - - - - - - - - - - - - - highbyte
84 return (i-(i%0x100))/0x100;
88 local function augment (t) -- - - - - - - - - - - - - - - - - - - - augment
90 for i,s in pairs(t) do
93 a[string.lower(s)] = s;
99 local function encode (t) -- - - - - - - - - - - - - - - - - - - - - encode
101 for i,s in pairs(t) do
102 local word = string.char(highbyte(i), i%0x100);
105 code[string.lower(s)] = word;
112 'A', 'NS', 'MD', 'MF', 'CNAME', 'SOA', 'MB', 'MG', 'MR', 'NULL', 'WKS',
113 'PTR', 'HINFO', 'MINFO', 'MX', 'TXT',
114 [ 28] = 'AAAA', [ 29] = 'LOC', [ 33] = 'SRV',
115 [252] = 'AXFR', [253] = 'MAILB', [254] = 'MAILA', [255] = '*' };
118 dns.classes = { 'IN', 'CS', 'CH', 'HS', [255] = '*' };
121 dns.type = augment (dns.types);
122 dns.class = augment (dns.classes);
123 dns.typecode = encode (dns.types);
124 dns.classcode = encode (dns.classes);
128 local function standardize(qname, qtype, qclass) -- - - - - - - standardize
129 if string.byte(qname, -1) ~= 0x2E then qname = qname..'.'; end
130 qname = string.lower(qname);
131 return qname, dns.type[qtype or 'A'], dns.class[qclass or 'IN'];
135 local function prune(rrs, time, soft) -- - - - - - - - - - - - - - - prune
136 time = time or socket.gettime();
137 for i,rr in pairs(rrs) do
139 -- rr.tod = rr.tod - 50 -- accelerated decripitude
140 rr.ttl = math.floor(rr.tod - time);
142 table.remove(rrs, i);
143 return prune(rrs, time, soft); -- Re-iterate
145 elseif soft == 'soft' then -- What is this? I forget!
153 -- metatables & co. ------------------------------------------ metatables & co.
157 resolver.__index = resolver;
159 resolver.timeout = default_timeout;
161 local function default_rr_tostring(rr)
162 local rr_val = rr.type and rr[rr.type:lower()];
163 if type(rr_val) ~= "string" then
164 return "<UNKNOWN RDATA TYPE>";
169 local special_tostrings = {
170 LOC = resolver.LOC_tostring;
172 return string.format('%2i %s', rr.pref, rr.mx);
176 return string.format('%5d %5d %5d %s', s.priority, s.weight, s.port, s.target);
180 local rr_metatable = {}; -- - - - - - - - - - - - - - - - - - - rr_metatable
181 function rr_metatable.__tostring(rr)
182 local rr_string = (special_tostrings[rr.type] or default_rr_tostring)(rr);
183 return string.format('%2s %-5s %6i %-28s %s', rr.class, rr.type, rr.ttl, rr.name, rr_string);
187 local rrs_metatable = {}; -- - - - - - - - - - - - - - - - - - rrs_metatable
188 function rrs_metatable.__tostring(rrs)
190 for i,rr in pairs(rrs) do
191 append(t, tostring(rr)..'\n');
193 return table.concat(t);
197 local cache_metatable = {}; -- - - - - - - - - - - - - - - - cache_metatable
198 function cache_metatable.__tostring(cache)
199 local time = socket.gettime();
201 for class,types in pairs(cache) do
202 for type,names in pairs(types) do
203 for name,rrs in pairs(names) do
205 append(t, tostring(rrs));
209 return table.concat(t);
213 function resolver:new() -- - - - - - - - - - - - - - - - - - - - - resolver
214 local r = { active = {}, cache = {}, unsorted = {} };
215 setmetatable(r, resolver);
216 setmetatable(r.cache, cache_metatable);
217 setmetatable(r.unsorted, { __mode = 'kv' });
222 -- packet layer -------------------------------------------------- packet layer
225 function dns.random(...) -- - - - - - - - - - - - - - - - - - - dns.random
226 math.randomseed(math.floor(10000*socket.gettime()) % 0x100000000);
227 dns.random = math.random;
228 return dns.random(...);
232 local function encodeHeader(o) -- - - - - - - - - - - - - - - encodeHeader
234 o.id = o.id or dns.random(0, 0xffff); -- 16b (random) id
236 o.rd = o.rd or 1; -- 1b 1 recursion desired
237 o.tc = o.tc or 0; -- 1b 1 truncated response
238 o.aa = o.aa or 0; -- 1b 1 authoritative response
239 o.opcode = o.opcode or 0; -- 4b 0 query
241 -- 2 server status request
243 o.qr = o.qr or 0; -- 1b 0 query, 1 response
245 o.rcode = o.rcode or 0; -- 4b 0 no error
252 o.z = o.z or 0; -- 3b 0 resvered
253 o.ra = o.ra or 0; -- 1b 1 recursion available
255 o.qdcount = o.qdcount or 1; -- 16b number of question RRs
256 o.ancount = o.ancount or 0; -- 16b number of answers RRs
257 o.nscount = o.nscount or 0; -- 16b number of nameservers RRs
258 o.arcount = o.arcount or 0; -- 16b number of additional RRs
260 -- string.char() rounds, so prevent roundup with -0.4999
261 local header = string.char(
262 highbyte(o.id), o.id %0x100,
263 o.rd + 2*o.tc + 4*o.aa + 8*o.opcode + 128*o.qr,
264 o.rcode + 16*o.z + 128*o.ra,
265 highbyte(o.qdcount), o.qdcount %0x100,
266 highbyte(o.ancount), o.ancount %0x100,
267 highbyte(o.nscount), o.nscount %0x100,
268 highbyte(o.arcount), o.arcount %0x100
275 local function encodeName(name) -- - - - - - - - - - - - - - - - encodeName
277 for part in string.gmatch(name, '[^.]+') do
278 append(t, string.char(string.len(part)));
281 append(t, string.char(0));
282 return table.concat(t);
286 local function encodeQuestion(qname, qtype, qclass) -- - - - encodeQuestion
287 qname = encodeName(qname);
288 qtype = dns.typecode[qtype or 'a'];
289 qclass = dns.classcode[qclass or 'in'];
290 return qname..qtype..qclass;
294 function resolver:byte(len) -- - - - - - - - - - - - - - - - - - - - - byte
296 local offset = self.offset;
297 local last = offset + len - 1;
298 if last > #self.packet then
299 error(string.format('out of bounds: %i>%i', last, #self.packet));
301 self.offset = offset + len;
302 return string.byte(self.packet, offset, last);
306 function resolver:word() -- - - - - - - - - - - - - - - - - - - - - - word
307 local b1, b2 = self:byte(2);
308 return 0x100*b1 + b2;
312 function resolver:dword () -- - - - - - - - - - - - - - - - - - - - - dword
313 local b1, b2, b3, b4 = self:byte(4);
314 --print('dword', b1, b2, b3, b4);
315 return 0x1000000*b1 + 0x10000*b2 + 0x100*b3 + b4;
319 function resolver:sub(len) -- - - - - - - - - - - - - - - - - - - - - - sub
321 local s = string.sub(self.packet, self.offset, self.offset + len - 1);
322 self.offset = self.offset + len;
327 function resolver:header(force) -- - - - - - - - - - - - - - - - - - header
328 local id = self:word();
329 --print(string.format(':header id %x', id));
330 if not self.active[id] and not force then return nil; end
332 local h = { id = id };
334 local b1, b2 = self:byte(2);
346 h.qdcount = self:word();
347 h.ancount = self:word();
348 h.nscount = self:word();
349 h.arcount = self:word();
351 for k,v in pairs(h) do h[k] = v-v%1; end
357 function resolver:name() -- - - - - - - - - - - - - - - - - - - - - - name
358 local remember, pointers = nil, 0;
359 local len = self:byte();
361 if len == 0 then return "." end -- Root label
363 if len >= 0xc0 then -- name is "compressed"
364 pointers = pointers + 1;
365 if pointers >= 20 then error('dns error: 20 pointers'); end;
366 local offset = ((len-0xc0)*0x100) + self:byte();
367 remember = remember or self.offset;
368 self.offset = offset + 1; -- +1 for lua
369 else -- name is not compressed
370 append(n, self:sub(len)..'.');
374 self.offset = remember or self.offset;
375 return table.concat(n);
379 function resolver:question() -- - - - - - - - - - - - - - - - - - question
381 q.name = self:name();
382 q.type = dns.type[self:word()];
383 q.class = dns.class[self:word()];
388 function resolver:A(rr) -- - - - - - - - - - - - - - - - - - - - - - - - A
389 local b1, b2, b3, b4 = self:byte(4);
390 rr.a = string.format('%i.%i.%i.%i', b1, b2, b3, b4);
393 function resolver:AAAA(rr)
395 for i = 1, rr.rdlength, 2 do
396 local b1, b2 = self:byte(2);
397 table.insert(addr, ("%02x%02x"):format(b1, b2));
399 addr = table.concat(addr, ":"):gsub("%f[%x]0+(%x)","%1");
401 for item in addr:gmatch(":[0:]+:") do
402 table.insert(zeros, item)
407 elseif #zeros > 1 then
408 table.sort(zeros, function(a, b) return #a > #b end);
410 rr.aaaa = addr:gsub(zeros[1], "::", 1):gsub("^0::", "::"):gsub("::0$", "::");
413 function resolver:CNAME(rr) -- - - - - - - - - - - - - - - - - - - - CNAME
414 rr.cname = self:name();
418 function resolver:MX(rr) -- - - - - - - - - - - - - - - - - - - - - - - MX
419 rr.pref = self:word();
424 function resolver:LOC_nibble_power() -- - - - - - - - - - LOC_nibble_power
425 local b = self:byte();
426 --print('nibbles', ((b-(b%0x10))/0x10), (b%0x10));
427 return ((b-(b%0x10))/0x10) * (10^(b%0x10));
431 function resolver:LOC(rr) -- - - - - - - - - - - - - - - - - - - - - - LOC
432 rr.version = self:byte();
433 if rr.version == 0 then
434 rr.loc = rr.loc or {};
435 rr.loc.size = self:LOC_nibble_power();
436 rr.loc.horiz_pre = self:LOC_nibble_power();
437 rr.loc.vert_pre = self:LOC_nibble_power();
438 rr.loc.latitude = self:dword();
439 rr.loc.longitude = self:dword();
440 rr.loc.altitude = self:dword();
445 local function LOC_tostring_degrees(f, pos, neg) -- - - - - - - - - - - - -
447 if f < 0 then pos = neg; f = -f; end
448 local deg, min, msec;
453 return string.format('%3d %2d %2.3f %s', deg, min, msec/1000, pos);
457 function resolver.LOC_tostring(rr) -- - - - - - - - - - - - - LOC_tostring
461 for k,name in pairs { 'size', 'horiz_pre', 'vert_pre', 'latitude', 'longitude', 'altitude' } do
462 append(t, string.format('%4s%-10s: %12.0f\n', '', name, rr.loc[name]));
466 append(t, string.format(
467 '%s %s %.2fm %.2fm %.2fm %.2fm',
468 LOC_tostring_degrees (rr.loc.latitude, 'N', 'S'),
469 LOC_tostring_degrees (rr.loc.longitude, 'E', 'W'),
470 (rr.loc.altitude - 10000000) / 100,
472 rr.loc.horiz_pre / 100,
473 rr.loc.vert_pre / 100
476 return table.concat(t);
480 function resolver:NS(rr) -- - - - - - - - - - - - - - - - - - - - - - - NS
485 function resolver:SOA(rr) -- - - - - - - - - - - - - - - - - - - - - - SOA
489 function resolver:SRV(rr) -- - - - - - - - - - - - - - - - - - - - - - SRV
491 rr.srv.priority = self:word();
492 rr.srv.weight = self:word();
493 rr.srv.port = self:word();
494 rr.srv.target = self:name();
497 function resolver:PTR(rr)
498 rr.ptr = self:name();
501 function resolver:TXT(rr) -- - - - - - - - - - - - - - - - - - - - - - TXT
502 rr.txt = self:sub (self:byte());
506 function resolver:rr() -- - - - - - - - - - - - - - - - - - - - - - - - rr
508 setmetatable(rr, rr_metatable);
509 rr.name = self:name(self);
510 rr.type = dns.type[self:word()] or rr.type;
511 rr.class = dns.class[self:word()] or rr.class;
512 rr.ttl = 0x10000*self:word() + self:word();
513 rr.rdlength = self:word();
516 rr.tod = self.time + 30;
518 rr.tod = self.time + rr.ttl;
521 local remember = self.offset;
522 local rr_parser = self[dns.type[rr.type]];
523 if rr_parser then rr_parser(self, rr); end
524 self.offset = remember;
525 rr.rdata = self:sub(rr.rdlength);
530 function resolver:rrs (count) -- - - - - - - - - - - - - - - - - - - - - rrs
532 for i = 1,count do append(rrs, self:rr()); end
537 function resolver:decode(packet, force) -- - - - - - - - - - - - - - decode
538 self.packet, self.offset = packet, 1;
539 local header = self:header(force);
540 if not header then return nil; end
541 local response = { header = header };
543 response.question = {};
544 local offset = self.offset;
545 for i = 1,response.header.qdcount do
546 append(response.question, self:question());
548 response.question.raw = string.sub(self.packet, offset, self.offset - 1);
551 if not self.active[response.header.id] or not self.active[response.header.id][response.question.raw] then
552 self.active[response.header.id] = nil;
557 response.answer = self:rrs(response.header.ancount);
558 response.authority = self:rrs(response.header.nscount);
559 response.additional = self:rrs(response.header.arcount);
565 -- socket layer -------------------------------------------------- socket layer
568 resolver.delays = { 1, 3 };
571 function resolver:addnameserver(address) -- - - - - - - - - - addnameserver
572 self.server = self.server or {};
573 append(self.server, address);
577 function resolver:setnameserver(address) -- - - - - - - - - - setnameserver
579 self:addnameserver(address);
583 function resolver:adddefaultnameservers() -- - - - - adddefaultnameservers
585 if windows and windows.get_nameservers then
586 for _, server in ipairs(windows.get_nameservers()) do
587 self:addnameserver(server);
590 if not self.server or #self.server == 0 then
591 -- TODO log warning about no nameservers, adding opendns servers as fallback
592 self:addnameserver("208.67.222.222");
593 self:addnameserver("208.67.220.220");
596 local resolv_conf = io.open("/etc/resolv.conf");
598 for line in resolv_conf:lines() do
599 line = line:gsub("#.*$", "")
600 :match('^%s*nameserver%s+(.*)%s*$');
602 line:gsub("%f[%d.](%d+%.%d+%.%d+%.%d+)%f[^%d.]", function (address)
603 self:addnameserver(address)
608 if not self.server or #self.server == 0 then
609 -- TODO log warning about no nameservers, adding localhost as the default nameserver
610 self:addnameserver("127.0.0.1");
616 function resolver:getsocket(servernum) -- - - - - - - - - - - - - getsocket
617 self.socket = self.socket or {};
618 self.socketset = self.socketset or {};
620 local sock = self.socket[servernum];
621 if sock then return sock; end
624 sock, err = socket.udp();
628 if self.socket_wrapper then sock = self.socket_wrapper(sock, self); end
630 -- todo: attempt to use a random port, fallback to 0
631 sock:setsockname('*', 0);
632 sock:setpeername(self.server[servernum], 53);
633 self.socket[servernum] = sock;
634 self.socketset[sock] = servernum;
638 function resolver:voidsocket(sock)
639 if self.socket[sock] then
640 self.socketset[self.socket[sock]] = nil;
641 self.socket[sock] = nil;
642 elseif self.socketset[sock] then
643 self.socket[self.socketset[sock]] = nil;
644 self.socketset[sock] = nil;
649 function resolver:socket_wrapper_set(func) -- - - - - - - socket_wrapper_set
650 self.socket_wrapper = func;
654 function resolver:closeall () -- - - - - - - - - - - - - - - - - - closeall
655 for i,sock in ipairs(self.socket) do
656 self.socket[i] = nil;
657 self.socketset[sock] = nil;
663 function resolver:remember(rr, type) -- - - - - - - - - - - - - - remember
664 --print ('remember', type, rr.class, rr.type, rr.name)
665 local qname, qtype, qclass = standardize(rr.name, rr.type, rr.class);
669 local all = get(self.cache, qclass, '*', qname);
670 --print('remember all', all);
671 if all then append(all, rr); end
674 self.cache = self.cache or setmetatable({}, cache_metatable);
675 local rrs = get(self.cache, qclass, type, qname) or
676 set(self.cache, qclass, type, qname, setmetatable({}, rrs_metatable));
679 if type == 'MX' then self.unsorted[rrs] = true; end
683 local function comp_mx(a, b) -- - - - - - - - - - - - - - - - - - - comp_mx
684 return (a.pref == b.pref) and (a.mx < b.mx) or (a.pref < b.pref);
688 function resolver:peek (qname, qtype, qclass) -- - - - - - - - - - - - peek
689 qname, qtype, qclass = standardize(qname, qtype, qclass);
690 local rrs = get(self.cache, qclass, qtype, qname);
691 if not rrs then return nil; end
692 if prune(rrs, socket.gettime()) and qtype == '*' or not next(rrs) then
693 set(self.cache, qclass, qtype, qname, nil);
696 if self.unsorted[rrs] then table.sort (rrs, comp_mx); end
701 function resolver:purge(soft) -- - - - - - - - - - - - - - - - - - - purge
702 if soft == 'soft' then
703 self.time = socket.gettime();
704 for class,types in pairs(self.cache or {}) do
705 for type,names in pairs(types) do
706 for name,rrs in pairs(names) do
707 prune(rrs, self.time, 'soft')
711 else self.cache = setmetatable({}, cache_metatable); end
715 function resolver:query(qname, qtype, qclass) -- - - - - - - - - - -- query
716 qname, qtype, qclass = standardize(qname, qtype, qclass)
718 if not self.server then self:adddefaultnameservers(); end
720 local question = encodeQuestion(qname, qtype, qclass);
721 local peek = self:peek (qname, qtype, qclass);
722 if peek then return peek; end
724 local header, id = encodeHeader();
725 --print ('query id', id, qclass, qtype, qname)
727 packet = header..question,
728 server = self.best_server,
730 retry = socket.gettime() + self.delays[1]
733 -- remember the query
734 self.active[id] = self.active[id] or {};
735 self.active[id][question] = o;
737 -- remember which coroutine wants the answer
738 local co = coroutine.running();
740 set(self.wanted, qclass, qtype, qname, co, true);
741 --set(self.yielded, co, qclass, qtype, qname, true);
744 local conn, err = self:getsocket(o.server)
750 if timer and self.timeout then
751 local num_servers = #self.server;
753 timer.add_task(self.timeout, function ()
754 if get(self.wanted, qclass, qtype, qname, co) then
755 if i < num_servers then
758 o.server = self.best_server;
759 conn, err = self:getsocket(o.server);
765 -- Tried everything, failed
766 self:cancel(qclass, qtype, qname, co, true);
773 function resolver:servfail(sock)
774 -- Resend all queries for this server
776 local num = self.socketset[sock]
778 -- Socket is dead now
779 self:voidsocket(sock);
781 -- Find all requests to the down server, and retry on the next server
782 self.time = socket.gettime();
783 for id,queries in pairs(self.active) do
784 for question,o in pairs(queries) do
785 if o.server == num then -- This request was to the broken server
786 o.server = o.server + 1 -- Use next server
787 if o.server > #self.server then
791 o.retries = (o.retries or 0) + 1;
792 if o.retries >= #self.server then
794 queries[question] = nil;
796 local _a = self:getsocket(o.server);
797 if _a then _a:send(o.packet); end
801 if next(queries) == nil then
802 self.active[id] = nil;
806 if num == self.best_server then
807 self.best_server = self.best_server + 1;
808 if self.best_server > #self.server then
809 -- Exhausted all servers, try first again
810 self.best_server = 1;
815 function resolver:settimeout(seconds)
816 self.timeout = seconds;
819 function resolver:receive(rset) -- - - - - - - - - - - - - - - - - receive
820 --print('receive'); print(self.socket);
821 self.time = socket.gettime();
822 rset = rset or self.socket;
825 for i,sock in pairs(rset) do
827 if self.socketset[sock] then
828 local packet = sock:receive();
830 response = self:decode(packet);
831 if response and self.active[response.header.id]
832 and self.active[response.header.id][response.question.raw] then
833 --print('received response');
834 --self.print(response);
836 for j,rr in pairs(response.answer) do
837 if rr.name:sub(-#response.question[1].name, -1) == response.question[1].name then
838 self:remember(rr, response.question[1].type)
843 local queries = self.active[response.header.id];
844 queries[response.question.raw] = nil;
846 if not next(queries) then self.active[response.header.id] = nil; end
847 if not next(self.active) then self:closeall(); end
849 -- was the query on the wanted list?
850 local q = response.question[1];
851 local cos = get(self.wanted, q.class, q.type, q.name);
853 for co in pairs(cos) do
854 set(self.yielded, co, q.class, q.type, q.name, nil);
855 if coroutine.status(co) == "suspended" then coroutine.resume(co); end
857 set(self.wanted, q.class, q.type, q.name, nil);
869 function resolver:feed(sock, packet, force)
870 --print('receive'); print(self.socket);
871 self.time = socket.gettime();
873 local response = self:decode(packet, force);
874 if response and self.active[response.header.id]
875 and self.active[response.header.id][response.question.raw] then
876 --print('received response');
877 --self.print(response);
879 for j,rr in pairs(response.answer) do
880 self:remember(rr, response.question[1].type);
884 local queries = self.active[response.header.id];
885 queries[response.question.raw] = nil;
886 if not next(queries) then self.active[response.header.id] = nil; end
887 if not next(self.active) then self:closeall(); end
889 -- was the query on the wanted list?
890 local q = response.question[1];
892 local cos = get(self.wanted, q.class, q.type, q.name);
894 for co in pairs(cos) do
895 set(self.yielded, co, q.class, q.type, q.name, nil);
896 if coroutine.status(co) == "suspended" then coroutine.resume(co); end
898 set(self.wanted, q.class, q.type, q.name, nil);
906 function resolver:cancel(qclass, qtype, qname, co, call_handler)
907 local cos = get(self.wanted, qclass, qtype, qname);
910 coroutine.resume(co);
916 function resolver:pulse() -- - - - - - - - - - - - - - - - - - - - - pulse
918 while self:receive() do end
919 if not next(self.active) then return nil; end
921 self.time = socket.gettime();
922 for id,queries in pairs(self.active) do
923 for question,o in pairs(queries) do
924 if self.time >= o.retry then
926 o.server = o.server + 1;
927 if o.server > #self.server then
929 o.delay = o.delay + 1;
932 if o.delay > #self.delays then
934 queries[question] = nil;
935 if not next(queries) then self.active[id] = nil; end
936 if not next(self.active) then return nil; end
938 --print('retry', o.server, o.delay);
939 local _a = self.socket[o.server];
940 if _a then _a:send(o.packet); end
941 o.retry = self.time + self.delays[o.delay];
947 if next(self.active) then return true; end
952 function resolver:lookup(qname, qtype, qclass) -- - - - - - - - - - lookup
953 self:query (qname, qtype, qclass)
954 while self:pulse() do
956 for i, s in ipairs(self.socket) do
959 socket.select(recvt, nil, 4)
962 return self:peek(qname, qtype, qclass);
965 function resolver:lookupex(handler, qname, qtype, qclass) -- - - - - - - - - - lookup
966 return self:peek(qname, qtype, qclass) or self:query(qname, qtype, qclass);
969 function resolver:tohostname(ip)
970 return dns.lookup(ip:gsub("(%d+)%.(%d+)%.(%d+)%.(%d+)", "%4.%3.%2.%1.in-addr.arpa."), "PTR");
973 --print ---------------------------------------------------------------- print
976 local hints = { -- - - - - - - - - - - - - - - - - - - - - - - - - - - hints
977 qr = { [0]='query', 'response' },
978 opcode = { [0]='query', 'inverse query', 'server status request' },
979 aa = { [0]='non-authoritative', 'authoritative' },
980 tc = { [0]='complete', 'truncated' },
981 rd = { [0]='recursion not desired', 'recursion desired' },
982 ra = { [0]='recursion not available', 'recursion available' },
983 z = { [0]='(reserved)' },
984 rcode = { [0]='no error', 'format error', 'server failure', 'name error', 'not implemented' },
991 local function hint(p, s) -- - - - - - - - - - - - - - - - - - - - - - hint
992 return (hints[s] and hints[s][p[s]]) or '';
996 function resolver.print(response) -- - - - - - - - - - - - - resolver.print
997 for s,s in pairs { 'id', 'qr', 'opcode', 'aa', 'tc', 'rd', 'ra', 'z',
998 'rcode', 'qdcount', 'ancount', 'nscount', 'arcount' } do
999 print( string.format('%-30s', 'header.'..s), response.header[s], hint(response.header, s) );
1002 for i,question in ipairs(response.question) do
1003 print(string.format ('question[%i].name ', i), question.name);
1004 print(string.format ('question[%i].type ', i), question.type);
1005 print(string.format ('question[%i].class ', i), question.class);
1008 local common = { name=1, type=1, class=1, ttl=1, rdlength=1, rdata=1 };
1010 for s,s in pairs({'answer', 'authority', 'additional'}) do
1011 for i,rr in pairs(response[s]) do
1012 for j,t in pairs({ 'name', 'type', 'class', 'ttl', 'rdlength' }) do
1013 tmp = string.format('%s[%i].%s', s, i, t);
1014 print(string.format('%-30s', tmp), rr[t], hint(rr, t));
1016 for j,t in pairs(rr) do
1017 if not common[j] then
1018 tmp = string.format('%s[%i].%s', s, i, j);
1019 print(string.format('%-30s %s', tostring(tmp), tostring(t)));
1027 -- module api ------------------------------------------------------ module api
1030 function dns.resolver () -- - - - - - - - - - - - - - - - - - - - - resolver
1031 -- this function seems to be redundant with resolver.new ()
1033 local r = { active = {}, cache = {}, unsorted = {}, wanted = {}, yielded = {}, best_server = 1 };
1034 setmetatable (r, resolver);
1035 setmetatable (r.cache, cache_metatable);
1036 setmetatable (r.unsorted, { __mode = 'kv' });
1040 local _resolver = dns.resolver();
1041 dns._resolver = _resolver;
1043 function dns.lookup(...) -- - - - - - - - - - - - - - - - - - - - - lookup
1044 return _resolver:lookup(...);
1047 function dns.tohostname(...)
1048 return _resolver:tohostname(...);
1051 function dns.purge(...) -- - - - - - - - - - - - - - - - - - - - - - purge
1052 return _resolver:purge(...);
1055 function dns.peek(...) -- - - - - - - - - - - - - - - - - - - - - - - peek
1056 return _resolver:peek(...);
1059 function dns.query(...) -- - - - - - - - - - - - - - - - - - - - - - query
1060 return _resolver:query(...);
1063 function dns.feed(...) -- - - - - - - - - - - - - - - - - - - - - - - feed
1064 return _resolver:feed(...);
1067 function dns.cancel(...) -- - - - - - - - - - - - - - - - - - - - - - cancel
1068 return _resolver:cancel(...);
1071 function dns.settimeout(...)
1072 return _resolver:settimeout(...);
1075 function dns.cache()
1076 return _resolver.cache;
1079 function dns.socket_wrapper_set(...) -- - - - - - - - - socket_wrapper_set
1080 return _resolver:socket_wrapper_set(...);