net/dns.lua

   1 -- Prosody IM
   2 -- This file is included with Prosody IM. It has modifications,
   3 -- which are hereby placed in the public domain.
   4
   5
   6 -- todo: quick (default) header generation
   7 -- todo: nxdomain, error handling
   8 -- todo: cache results of encodeName
   9
  10
  11 -- reference: http://tools.ietf.org/html/rfc1035
  12 -- reference: http://tools.ietf.org/html/rfc1876 (LOC)
  13
  14
  15 local socket = require "socket";
  16 local timer = require "util.timer";
  17
  18 local _, windows = pcall(require, "util.windows");
  19 local is_windows = (_ and windows) or os.getenv("WINDIR");
  20
  21 local coroutine, io, math, string, table =
  22       coroutine, io, math, string, table;
  23
  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;
  26
  27 local ztact = { -- public domain 20080404 lua@ztact.com
  28         get = function(parent, ...)
  29                 local len = select('#', ...);
  30                 for i=1,len do
  31                         parent = parent[select(i, ...)];
  32                         if parent == nil then break; end
  33                 end
  34                 return parent;
  35         end;
  36         set = function(parent, ...)
  37                 local len = select('#', ...);
  38                 local key, value = select(len-1, ...);
  39                 local cutpoint, cutkey;
  40
  41                 for i=1,len-2 do
  42                         local key = select (i, ...)
  43                         local child = parent[key]
  44
  45                         if value == nil then
  46                                 if child == nil then
  47                                         return;
  48                                 elseif next(child, next(child)) then
  49                                         cutpoint = nil; cutkey = nil;
  50                                 elseif cutpoint == nil then
  51                                         cutpoint = parent; cutkey = key;
  52                                 end
  53                         elseif child == nil then
  54                                 child = {};
  55                                 parent[key] = child;
  56                         end
  57                         parent = child
  58                 end
  59
  60                 if value == nil and cutpoint then
  61                         cutpoint[cutkey] = nil;
  62                 else
  63                         parent[key] = value;
  64                         return value;
  65                 end
  66         end;
  67 };
  68 local get, set = ztact.get, ztact.set;
  69
  70 local default_timeout = 15;
  71
  72 -------------------------------------------------- module dns
  73 module('dns')
  74 local dns = _M;
  75
  76
  77 -- dns type & class codes ------------------------------ dns type & class codes
  78
  79
  80 local append = table.insert
  81
  82
  83 local function highbyte(i)    -- - - - - - - - - - - - - - - - - - -  highbyte
  84         return (i-(i%0x100))/0x100;
  85 end
  86
  87
  88 local function augment (t)    -- - - - - - - - - - - - - - - - - - - -  augment
  89         local a = {};
  90         for i,s in pairs(t) do
  91                 a[i] = s;
  92                 a[s] = s;
  93                 a[string.lower(s)] = s;
  94         end
  95         return a;
  96 end
  97
  98
  99 local function encode (t)    -- - - - - - - - - - - - - - - - - - - - -  encode
 100         local code = {};
 101         for i,s in pairs(t) do
 102                 local word = string.char(highbyte(i), i%0x100);
 103                 code[i] = word;
 104                 code[s] = word;
 105                 code[string.lower(s)] = word;
 106         end
 107         return code;
 108 end
 109
 110
 111 dns.types = {
 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] = '*' };
 116
 117
 118 dns.classes = { 'IN', 'CS', 'CH', 'HS', [255] = '*' };
 119
 120
 121 dns.type      = augment (dns.types);
 122 dns.class     = augment (dns.classes);
 123 dns.typecode  = encode  (dns.types);
 124 dns.classcode = encode  (dns.classes);
 125
 126
 127
 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'];
 132 end
 133
 134
 135 local function prune(rrs, time, soft)    -- - - - - - - - - - - - - - -  prune
 136         time = time or socket.gettime();
 137         for i,rr in ipairs(rrs) do
 138                 if rr.tod then
 139                         -- rr.tod = rr.tod - 50    -- accelerated decripitude
 140                         rr.ttl = math.floor(rr.tod - time);
 141                         if rr.ttl <= 0 then
 142                                 rrs[rr[rr.type:lower()]] = nil;
 143                                 table.remove(rrs, i);
 144                                 return prune(rrs, time, soft); -- Re-iterate
 145                         end
 146                 elseif soft == 'soft' then    -- What is this?  I forget!
 147                         assert(rr.ttl == 0);
 148                         rrs[rr[rr.type:lower()]] = nil;
 149                         table.remove(rrs, i);
 150                 end
 151         end
 152 end
 153
 154
 155 -- metatables & co. ------------------------------------------ metatables & co.
 156
 157
 158 local resolver = {};
 159 resolver.__index = resolver;
 160
 161 resolver.timeout = default_timeout;
 162
 163 local function default_rr_tostring(rr)
 164         local rr_val = rr.type and rr[rr.type:lower()];
 165         if type(rr_val) ~= "string" then
 166                 return "<UNKNOWN RDATA TYPE>";
 167         end
 168         return rr_val;
 169 end
 170
 171 local special_tostrings = {
 172         LOC = resolver.LOC_tostring;
 173         MX  = function (rr)
 174                 return string.format('%2i %s', rr.pref, rr.mx);
 175         end;
 176         SRV = function (rr)
 177                 local s = rr.srv;
 178                 return string.format('%5d %5d %5d %s', s.priority, s.weight, s.port, s.target);
 179         end;
 180 };
 181
 182 local rr_metatable = {};   -- - - - - - - - - - - - - - - - - - -  rr_metatable
 183 function rr_metatable.__tostring(rr)
 184         local rr_string = (special_tostrings[rr.type] or default_rr_tostring)(rr);
 185         return string.format('%2s %-5s %6i %-28s %s', rr.class, rr.type, rr.ttl, rr.name, rr_string);
 186 end
 187
 188
 189 local rrs_metatable = {};    -- - - - - - - - - - - - - - - - - -  rrs_metatable
 190 function rrs_metatable.__tostring(rrs)
 191         local t = {};
 192         for i,rr in ipairs(rrs) do
 193                 append(t, tostring(rr)..'\n');
 194         end
 195         return table.concat(t);
 196 end
 197
 198
 199 local cache_metatable = {};    -- - - - - - - - - - - - - - - -  cache_metatable
 200 function cache_metatable.__tostring(cache)
 201         local time = socket.gettime();
 202         local t = {};
 203         for class,types in pairs(cache) do
 204                 for type,names in pairs(types) do
 205                         for name,rrs in pairs(names) do
 206                                 prune(rrs, time);
 207                                 append(t, tostring(rrs));
 208                         end
 209                 end
 210         end
 211         return table.concat(t);
 212 end
 213
 214
 215 function resolver:new()    -- - - - - - - - - - - - - - - - - - - - - resolver
 216         local r = { active = {}, cache = {}, unsorted = {} };
 217         setmetatable(r, resolver);
 218         setmetatable(r.cache, cache_metatable);
 219         setmetatable(r.unsorted, { __mode = 'kv' });
 220         return r;
 221 end
 222
 223
 224 -- packet layer -------------------------------------------------- packet layer
 225
 226
 227 function dns.random(...)    -- - - - - - - - - - - - - - - - - - -  dns.random
 228         math.randomseed(math.floor(10000*socket.gettime()) % 0x100000000);
 229         dns.random = math.random;
 230         return dns.random(...);
 231 end
 232
 233
 234 local function encodeHeader(o)    -- - - - - - - - - - - - - - -  encodeHeader
 235         o = o or {};
 236         o.id = o.id or dns.random(0, 0xffff); -- 16b    (random) id
 237
 238         o.rd = o.rd or 1;               --  1b  1 recursion desired
 239         o.tc = o.tc or 0;               --  1b  1 truncated response
 240         o.aa = o.aa or 0;               --  1b  1 authoritative response
 241         o.opcode = o.opcode or 0;       --  4b  0 query
 242                                 --  1 inverse query
 243                                 --      2 server status request
 244                                 --      3-15 reserved
 245         o.qr = o.qr or 0;               --  1b  0 query, 1 response
 246
 247         o.rcode = o.rcode or 0; --  4b  0 no error
 248                                 --      1 format error
 249                                 --      2 server failure
 250                                 --      3 name error
 251                                 --      4 not implemented
 252                                 --      5 refused
 253                                 --      6-15 reserved
 254         o.z = o.z  or 0;                --  3b  0 resvered
 255         o.ra = o.ra or 0;               --  1b  1 recursion available
 256
 257         o.qdcount = o.qdcount or 1;     -- 16b  number of question RRs
 258         o.ancount = o.ancount or 0;     -- 16b  number of answers RRs
 259         o.nscount = o.nscount or 0;     -- 16b  number of nameservers RRs
 260         o.arcount = o.arcount or 0;     -- 16b  number of additional RRs
 261
 262         -- string.char() rounds, so prevent roundup with -0.4999
 263         local header = string.char(
 264                 highbyte(o.id), o.id %0x100,
 265                 o.rd + 2*o.tc + 4*o.aa + 8*o.opcode + 128*o.qr,
 266                 o.rcode + 16*o.z + 128*o.ra,
 267                 highbyte(o.qdcount),  o.qdcount %0x100,
 268                 highbyte(o.ancount),  o.ancount %0x100,
 269                 highbyte(o.nscount),  o.nscount %0x100,
 270                 highbyte(o.arcount),  o.arcount %0x100
 271         );
 272
 273         return header, o.id;
 274 end
 275
 276
 277 local function encodeName(name)    -- - - - - - - - - - - - - - - - encodeName
 278         local t = {};
 279         for part in string.gmatch(name, '[^.]+') do
 280                 append(t, string.char(string.len(part)));
 281                 append(t, part);
 282         end
 283         append(t, string.char(0));
 284         return table.concat(t);
 285 end
 286
 287
 288 local function encodeQuestion(qname, qtype, qclass)    -- - - - encodeQuestion
 289         qname  = encodeName(qname);
 290         qtype  = dns.typecode[qtype or 'a'];
 291         qclass = dns.classcode[qclass or 'in'];
 292         return qname..qtype..qclass;
 293 end
 294
 295
 296 function resolver:byte(len)    -- - - - - - - - - - - - - - - - - - - - - byte
 297         len = len or 1;
 298         local offset = self.offset;
 299         local last = offset + len - 1;
 300         if last > #self.packet then
 301                 error(string.format('out of bounds: %i>%i', last, #self.packet));
 302         end
 303         self.offset = offset + len;
 304         return string.byte(self.packet, offset, last);
 305 end
 306
 307
 308 function resolver:word()    -- - - - - - - - - - - - - - - - - - - - - -  word
 309         local b1, b2 = self:byte(2);
 310         return 0x100*b1 + b2;
 311 end
 312
 313
 314 function resolver:dword ()    -- - - - - - - - - - - - - - - - - - - - -  dword
 315         local b1, b2, b3, b4 = self:byte(4);
 316         --print('dword', b1, b2, b3, b4);
 317         return 0x1000000*b1 + 0x10000*b2 + 0x100*b3 + b4;
 318 end
 319
 320
 321 function resolver:sub(len)    -- - - - - - - - - - - - - - - - - - - - - - sub
 322         len = len or 1;
 323         local s = string.sub(self.packet, self.offset, self.offset + len - 1);
 324         self.offset = self.offset + len;
 325         return s;
 326 end
 327
 328
 329 function resolver:header(force)    -- - - - - - - - - - - - - - - - - - header
 330         local id = self:word();
 331         --print(string.format(':header  id  %x', id));
 332         if not self.active[id] and not force then return nil; end
 333
 334         local h = { id = id };
 335
 336         local b1, b2 = self:byte(2);
 337
 338         h.rd      = b1 %2;
 339         h.tc      = b1 /2%2;
 340         h.aa      = b1 /4%2;
 341         h.opcode  = b1 /8%16;
 342         h.qr      = b1 /128;
 343
 344         h.rcode   = b2 %16;
 345         h.z       = b2 /16%8;
 346         h.ra      = b2 /128;
 347
 348         h.qdcount = self:word();
 349         h.ancount = self:word();
 350         h.nscount = self:word();
 351         h.arcount = self:word();
 352
 353         for k,v in pairs(h) do h[k] = v-v%1; end
 354
 355         return h;
 356 end
 357
 358
 359 function resolver:name()    -- - - - - - - - - - - - - - - - - - - - - -  name
 360         local remember, pointers = nil, 0;
 361         local len = self:byte();
 362         local n = {};
 363         if len == 0 then return "." end -- Root label
 364         while len > 0 do
 365                 if len >= 0xc0 then    -- name is "compressed"
 366                         pointers = pointers + 1;
 367                         if pointers >= 20 then error('dns error: 20 pointers'); end;
 368                         local offset = ((len-0xc0)*0x100) + self:byte();
 369                         remember = remember or self.offset;
 370                         self.offset = offset + 1;    -- +1 for lua
 371                 else    -- name is not compressed
 372                         append(n, self:sub(len)..'.');
 373                 end
 374                 len = self:byte();
 375         end
 376         self.offset = remember or self.offset;
 377         return table.concat(n);
 378 end
 379
 380
 381 function resolver:question()    -- - - - - - - - - - - - - - - - - -  question
 382         local q = {};
 383         q.name  = self:name();
 384         q.type  = dns.type[self:word()];
 385         q.class = dns.class[self:word()];
 386         return q;
 387 end
 388
 389
 390 function resolver:A(rr)    -- - - - - - - - - - - - - - - - - - - - - - - -  A
 391         local b1, b2, b3, b4 = self:byte(4);
 392         rr.a = string.format('%i.%i.%i.%i', b1, b2, b3, b4);
 393 end
 394
 395 function resolver:AAAA(rr)
 396         local addr = {};
 397         for i = 1, rr.rdlength, 2 do
 398                 local b1, b2 = self:byte(2);
 399                 table.insert(addr, ("%02x%02x"):format(b1, b2));
 400         end
 401         addr = table.concat(addr, ":"):gsub("%f[%x]0+(%x)","%1");
 402         local zeros = {};
 403         for item in addr:gmatch(":[0:]+:") do
 404                 table.insert(zeros, item)
 405         end
 406         if #zeros == 0 then
 407                 rr.aaaa = addr;
 408                 return
 409         elseif #zeros > 1 then
 410                 table.sort(zeros, function(a, b) return #a > #b end);
 411         end
 412         rr.aaaa = addr:gsub(zeros[1], "::", 1):gsub("^0::", "::"):gsub("::0$", "::");
 413 end
 414
 415 function resolver:CNAME(rr)    -- - - - - - - - - - - - - - - - - - - -  CNAME
 416         rr.cname = self:name();
 417 end
 418
 419
 420 function resolver:MX(rr)    -- - - - - - - - - - - - - - - - - - - - - - -  MX
 421         rr.pref = self:word();
 422         rr.mx   = self:name();
 423 end
 424
 425
 426 function resolver:LOC_nibble_power()    -- - - - - - - - - -  LOC_nibble_power
 427         local b = self:byte();
 428         --print('nibbles', ((b-(b%0x10))/0x10), (b%0x10));
 429         return ((b-(b%0x10))/0x10) * (10^(b%0x10));
 430 end
 431
 432
 433 function resolver:LOC(rr)    -- - - - - - - - - - - - - - - - - - - - - -  LOC
 434         rr.version = self:byte();
 435         if rr.version == 0 then
 436                 rr.loc           = rr.loc or {};
 437                 rr.loc.size      = self:LOC_nibble_power();
 438                 rr.loc.horiz_pre = self:LOC_nibble_power();
 439                 rr.loc.vert_pre  = self:LOC_nibble_power();
 440                 rr.loc.latitude  = self:dword();
 441                 rr.loc.longitude = self:dword();
 442                 rr.loc.altitude  = self:dword();
 443         end
 444 end
 445
 446
 447 local function LOC_tostring_degrees(f, pos, neg)    -- - - - - - - - - - - - -
 448         f = f - 0x80000000;
 449         if f < 0 then pos = neg; f = -f; end
 450         local deg, min, msec;
 451         msec = f%60000;
 452         f    = (f-msec)/60000;
 453         min  = f%60;
 454         deg = (f-min)/60;
 455         return string.format('%3d %2d %2.3f %s', deg, min, msec/1000, pos);
 456 end
 457
 458
 459 function resolver.LOC_tostring(rr)    -- - - - - - - - - - - - -  LOC_tostring
 460         local t = {};
 461
 462         --[[
 463         for k,name in pairs { 'size', 'horiz_pre', 'vert_pre', 'latitude', 'longitude', 'altitude' } do
 464                 append(t, string.format('%4s%-10s: %12.0f\n', '', name, rr.loc[name]));
 465         end
 466         --]]
 467
 468         append(t, string.format(
 469                 '%s    %s    %.2fm %.2fm %.2fm %.2fm',
 470                 LOC_tostring_degrees (rr.loc.latitude, 'N', 'S'),
 471                 LOC_tostring_degrees (rr.loc.longitude, 'E', 'W'),
 472                 (rr.loc.altitude - 10000000) / 100,
 473                 rr.loc.size / 100,
 474                 rr.loc.horiz_pre / 100,
 475                 rr.loc.vert_pre / 100
 476         ));
 477
 478         return table.concat(t);
 479 end
 480
 481
 482 function resolver:NS(rr)    -- - - - - - - - - - - - - - - - - - - - - - -  NS
 483         rr.ns = self:name();
 484 end
 485
 486
 487 function resolver:SOA(rr)    -- - - - - - - - - - - - - - - - - - - - - -  SOA
 488 end
 489
 490
 491 function resolver:SRV(rr)    -- - - - - - - - - - - - - - - - - - - - - -  SRV
 492           rr.srv = {};
 493           rr.srv.priority = self:word();
 494           rr.srv.weight   = self:word();
 495           rr.srv.port     = self:word();
 496           rr.srv.target   = self:name();
 497 end
 498
 499 function resolver:PTR(rr)
 500         rr.ptr = self:name();
 501 end
 502
 503 function resolver:TXT(rr)    -- - - - - - - - - - - - - - - - - - - - - -  TXT
 504         rr.txt = self:sub (self:byte());
 505 end
 506
 507
 508 function resolver:rr()    -- - - - - - - - - - - - - - - - - - - - - - - -  rr
 509         local rr = {};
 510         setmetatable(rr, rr_metatable);
 511         rr.name     = self:name(self);
 512         rr.type     = dns.type[self:word()] or rr.type;
 513         rr.class    = dns.class[self:word()] or rr.class;
 514         rr.ttl      = 0x10000*self:word() + self:word();
 515         rr.rdlength = self:word();
 516
 517         if rr.ttl <= 0 then
 518                 rr.tod = self.time + 30;
 519         else
 520                 rr.tod = self.time + rr.ttl;
 521         end
 522
 523         local remember = self.offset;
 524         local rr_parser = self[dns.type[rr.type]];
 525         if rr_parser then rr_parser(self, rr); end
 526         self.offset = remember;
 527         rr.rdata = self:sub(rr.rdlength);
 528         return rr;
 529 end
 530
 531
 532 function resolver:rrs (count)    -- - - - - - - - - - - - - - - - - - - - - rrs
 533         local rrs = {};
 534         for i = 1,count do append(rrs, self:rr()); end
 535         return rrs;
 536 end
 537
 538
 539 function resolver:decode(packet, force)    -- - - - - - - - - - - - - - decode
 540         self.packet, self.offset = packet, 1;
 541         local header = self:header(force);
 542         if not header then return nil; end
 543         local response = { header = header };
 544
 545         response.question = {};
 546         local offset = self.offset;
 547         for i = 1,response.header.qdcount do
 548                 append(response.question, self:question());
 549         end
 550         response.question.raw = string.sub(self.packet, offset, self.offset - 1);
 551
 552         if not force then
 553                 if not self.active[response.header.id] or not self.active[response.header.id][response.question.raw] then
 554                         self.active[response.header.id] = nil;
 555                         return nil;
 556                 end
 557         end
 558
 559         response.answer     = self:rrs(response.header.ancount);
 560         response.authority  = self:rrs(response.header.nscount);
 561         response.additional = self:rrs(response.header.arcount);
 562
 563         return response;
 564 end
 565
 566
 567 -- socket layer -------------------------------------------------- socket layer
 568
 569
 570 resolver.delays = { 1, 3 };
 571
 572
 573 function resolver:addnameserver(address)    -- - - - - - - - - - addnameserver
 574         self.server = self.server or {};
 575         append(self.server, address);
 576 end
 577
 578
 579 function resolver:setnameserver(address)    -- - - - - - - - - - setnameserver
 580         self.server = {};
 581         self:addnameserver(address);
 582 end
 583
 584
 585 function resolver:adddefaultnameservers()    -- - - - -  adddefaultnameservers
 586         if is_windows then
 587                 if windows and windows.get_nameservers then
 588                         for _, server in ipairs(windows.get_nameservers()) do
 589                                 self:addnameserver(server);
 590                         end
 591                 end
 592                 if not self.server or #self.server == 0 then
 593                         -- TODO log warning about no nameservers, adding opendns servers as fallback
 594                         self:addnameserver("208.67.222.222");
 595                         self:addnameserver("208.67.220.220");
 596                 end
 597         else -- posix
 598                 local resolv_conf = io.open("/etc/resolv.conf");
 599                 if resolv_conf then
 600                         for line in resolv_conf:lines() do
 601                                 line = line:gsub("#.*$", "")
 602                                         :match('^%s*nameserver%s+(.*)%s*$');
 603                                 if line then
 604                                         line:gsub("%f[%d.](%d+%.%d+%.%d+%.%d+)%f[^%d.]", function (address)
 605                                                 self:addnameserver(address)
 606                                         end);
 607                                 end
 608                         end
 609                 end
 610                 if not self.server or #self.server == 0 then
 611                         -- TODO log warning about no nameservers, adding localhost as the default nameserver
 612                         self:addnameserver("127.0.0.1");
 613                 end
 614         end
 615 end
 616
 617
 618 function resolver:getsocket(servernum)    -- - - - - - - - - - - - - getsocket
 619         self.socket = self.socket or {};
 620         self.socketset = self.socketset or {};
 621
 622         local sock = self.socket[servernum];
 623         if sock then return sock; end
 624
 625         local err;
 626         sock, err = socket.udp();
 627         if sock and self.socket_wrapper then sock, err = self.socket_wrapper(sock, self); end
 628         if not sock then
 629                 return nil, err;
 630         end
 631         sock:settimeout(0);
 632         -- todo: attempt to use a random port, fallback to 0
 633         sock:setsockname('*', 0);
 634         sock:setpeername(self.server[servernum], 53);
 635         self.socket[servernum] = sock;
 636         self.socketset[sock] = servernum;
 637         return sock;
 638 end
 639
 640 function resolver:voidsocket(sock)
 641         if self.socket[sock] then
 642                 self.socketset[self.socket[sock]] = nil;
 643                 self.socket[sock] = nil;
 644         elseif self.socketset[sock] then
 645                 self.socket[self.socketset[sock]] = nil;
 646                 self.socketset[sock] = nil;
 647         end
 648         sock:close();
 649 end
 650
 651 function resolver:socket_wrapper_set(func)  -- - - - - - - socket_wrapper_set
 652         self.socket_wrapper = func;
 653 end
 654
 655
 656 function resolver:closeall ()    -- - - - - - - - - - - - - - - - - -  closeall
 657         for i,sock in ipairs(self.socket) do
 658                 self.socket[i] = nil;
 659                 self.socketset[sock] = nil;
 660                 sock:close();
 661         end
 662 end
 663
 664
 665 function resolver:remember(rr, type)    -- - - - - - - - - - - - - -  remember
 666         --print ('remember', type, rr.class, rr.type, rr.name)
 667         local qname, qtype, qclass = standardize(rr.name, rr.type, rr.class);
 668
 669         if type ~= '*' then
 670                 type = qtype;
 671                 local all = get(self.cache, qclass, '*', qname);
 672                 --print('remember all', all);
 673                 if all then append(all, rr); end
 674         end
 675
 676         self.cache = self.cache or setmetatable({}, cache_metatable);
 677         local rrs = get(self.cache, qclass, type, qname) or
 678                 set(self.cache, qclass, type, qname, setmetatable({}, rrs_metatable));
 679         if not rrs[rr[qtype:lower()]] then
 680                 rrs[rr[qtype:lower()]] = true;
 681                 append(rrs, rr);
 682         end
 683
 684         if type == 'MX' then self.unsorted[rrs] = true; end
 685 end
 686
 687
 688 local function comp_mx(a, b)    -- - - - - - - - - - - - - - - - - - - comp_mx
 689         return (a.pref == b.pref) and (a.mx < b.mx) or (a.pref < b.pref);
 690 end
 691
 692
 693 function resolver:peek (qname, qtype, qclass)    -- - - - - - - - - - - -  peek
 694         qname, qtype, qclass = standardize(qname, qtype, qclass);
 695         local rrs = get(self.cache, qclass, qtype, qname);
 696         if not rrs then return nil; end
 697         if prune(rrs, socket.gettime()) and qtype == '*' or not next(rrs) then
 698                 set(self.cache, qclass, qtype, qname, nil);
 699                 return nil;
 700         end
 701         if self.unsorted[rrs] then table.sort (rrs, comp_mx); end
 702         return rrs;
 703 end
 704
 705
 706 function resolver:purge(soft)    -- - - - - - - - - - - - - - - - - - -  purge
 707         if soft == 'soft' then
 708                 self.time = socket.gettime();
 709                 for class,types in pairs(self.cache or {}) do
 710                         for type,names in pairs(types) do
 711                                 for name,rrs in pairs(names) do
 712                                         prune(rrs, self.time, 'soft')
 713                                 end
 714                         end
 715                 end
 716         else self.cache = setmetatable({}, cache_metatable); end
 717 end
 718
 719
 720 function resolver:query(qname, qtype, qclass)    -- - - - - - - - - - -- query
 721         qname, qtype, qclass = standardize(qname, qtype, qclass)
 722
 723         local co = coroutine.running();
 724         local q = get(self.wanted, qclass, qtype, qname);
 725         if co and q then
 726                 -- We are already waiting for a reply to an identical query.
 727                 set(self.wanted, qclass, qtype, qname, co, true);
 728                 return true;
 729         end
 730
 731         if not self.server then self:adddefaultnameservers(); end
 732
 733         local question = encodeQuestion(qname, qtype, qclass);
 734         local peek = self:peek (qname, qtype, qclass);
 735         if peek then return peek; end
 736
 737         local header, id = encodeHeader();
 738         --print ('query  id', id, qclass, qtype, qname)
 739         local o = {
 740                 packet = header..question,
 741                 server = self.best_server,
 742                 delay  = 1,
 743                 retry  = socket.gettime() + self.delays[1]
 744         };
 745
 746         -- remember the query
 747         self.active[id] = self.active[id] or {};
 748         self.active[id][question] = o;
 749
 750         -- remember which coroutine wants the answer
 751         if co then
 752                 set(self.wanted, qclass, qtype, qname, co, true);
 753         end
 754
 755         local conn, err = self:getsocket(o.server)
 756         if not conn then
 757                 return nil, err;
 758         end
 759         conn:send (o.packet)
 760
 761         if timer and self.timeout then
 762                 local num_servers = #self.server;
 763                 local i = 1;
 764                 timer.add_task(self.timeout, function ()
 765                         if get(self.wanted, qclass, qtype, qname, co) then
 766                                 if i < num_servers then
 767                                         i = i + 1;
 768                                         self:servfail(conn);
 769                                         o.server = self.best_server;
 770                                         conn, err = self:getsocket(o.server);
 771                                         if conn then
 772                                                 conn:send(o.packet);
 773                                                 return self.timeout;
 774                                         end
 775                                 end
 776                                 -- Tried everything, failed
 777                                 self:cancel(qclass, qtype, qname);
 778                         end
 779                 end)
 780         end
 781         return true;
 782 end
 783
 784 function resolver:servfail(sock)
 785         -- Resend all queries for this server
 786
 787         local num = self.socketset[sock]
 788
 789         -- Socket is dead now
 790         sock = self:voidsocket(sock);
 791
 792         -- Find all requests to the down server, and retry on the next server
 793         self.time = socket.gettime();
 794         for id,queries in pairs(self.active) do
 795                 for question,o in pairs(queries) do
 796                         if o.server == num then -- This request was to the broken server
 797                                 o.server = o.server + 1 -- Use next server
 798                                 if o.server > #self.server then
 799                                         o.server = 1;
 800                                 end
 801
 802                                 o.retries = (o.retries or 0) + 1;
 803                                 if o.retries >= #self.server then
 804                                         --print('timeout');
 805                                         queries[question] = nil;
 806                                 else
 807                                         sock = self:getsocket(o.server);
 808                                         if sock then sock:send(o.packet); end
 809                                 end
 810                         end
 811                 end
 812                 if next(queries) == nil then
 813                         self.active[id] = nil;
 814                 end
 815         end
 816
 817         if num == self.best_server then
 818                 self.best_server = self.best_server + 1;
 819                 if self.best_server > #self.server then
 820                         -- Exhausted all servers, try first again
 821                         self.best_server = 1;
 822                 end
 823         end
 824         return sock;
 825 end
 826
 827 function resolver:settimeout(seconds)
 828         self.timeout = seconds;
 829 end
 830
 831 function resolver:receive(rset)    -- - - - - - - - - - - - - - - - -  receive
 832         --print('receive');  print(self.socket);
 833         self.time = socket.gettime();
 834         rset = rset or self.socket;
 835
 836         local response;
 837         for i,sock in pairs(rset) do
 838
 839                 if self.socketset[sock] then
 840                         local packet = sock:receive();
 841                         if packet then
 842                                 response = self:decode(packet);
 843                                 if response and self.active[response.header.id]
 844                                         and self.active[response.header.id][response.question.raw] then
 845                                         --print('received response');
 846                                         --self.print(response);
 847
 848                                         for j,rr in pairs(response.answer) do
 849                                                 if rr.name:sub(-#response.question[1].name, -1) == response.question[1].name then
 850                                                         self:remember(rr, response.question[1].type)
 851                                                 end
 852                                         end
 853
 854                                         -- retire the query
 855                                         local queries = self.active[response.header.id];
 856                                         queries[response.question.raw] = nil;
 857
 858                                         if not next(queries) then self.active[response.header.id] = nil; end
 859                                         if not next(self.active) then self:closeall(); end
 860
 861                                         -- was the query on the wanted list?
 862                                         local q = response.question[1];
 863                                         local cos = get(self.wanted, q.class, q.type, q.name);
 864                                         if cos then
 865                                                 for co in pairs(cos) do
 866                                                         if coroutine.status(co) == "suspended" then coroutine.resume(co); end
 867                                                 end
 868                                                 set(self.wanted, q.class, q.type, q.name, nil);
 869                                         end
 870                                 end
 871
 872                         end
 873                 end
 874         end
 875
 876         return response;
 877 end
 878
 879
 880 function resolver:feed(sock, packet, force)
 881         --print('receive'); print(self.socket);
 882         self.time = socket.gettime();
 883
 884         local response = self:decode(packet, force);
 885         if response and self.active[response.header.id]
 886                 and self.active[response.header.id][response.question.raw] then
 887                 --print('received response');
 888                 --self.print(response);
 889
 890                 for j,rr in pairs(response.answer) do
 891                         self:remember(rr, response.question[1].type);
 892                 end
 893
 894                 -- retire the query
 895                 local queries = self.active[response.header.id];
 896                 queries[response.question.raw] = nil;
 897                 if not next(queries) then self.active[response.header.id] = nil; end
 898                 if not next(self.active) then self:closeall(); end
 899
 900                 -- was the query on the wanted list?
 901                 local q = response.question[1];
 902                 if q then
 903                         local cos = get(self.wanted, q.class, q.type, q.name);
 904                         if cos then
 905                                 for co in pairs(cos) do
 906                                         if coroutine.status(co) == "suspended" then coroutine.resume(co); end
 907                                 end
 908                                 set(self.wanted, q.class, q.type, q.name, nil);
 909                         end
 910                 end
 911         end
 912
 913         return response;
 914 end
 915
 916 function resolver:cancel(qclass, qtype, qname)
 917         local cos = get(self.wanted, qclass, qtype, qname);
 918         if cos then
 919                 for co in pairs(cos) do
 920                         if coroutine.status(co) == "suspended" then coroutine.resume(co); end
 921                 end
 922                 set(self.wanted, qclass, qtype, qname, nil);
 923         end
 924 end
 925
 926 function resolver:pulse()    -- - - - - - - - - - - - - - - - - - - - -  pulse
 927         --print(':pulse');
 928         while self:receive() do end
 929         if not next(self.active) then return nil; end
 930
 931         self.time = socket.gettime();
 932         for id,queries in pairs(self.active) do
 933                 for question,o in pairs(queries) do
 934                         if self.time >= o.retry then
 935
 936                                 o.server = o.server + 1;
 937                                 if o.server > #self.server then
 938                                         o.server = 1;
 939                                         o.delay = o.delay + 1;
 940                                 end
 941
 942                                 if o.delay > #self.delays then
 943                                         --print('timeout');
 944                                         queries[question] = nil;
 945                                         if not next(queries) then self.active[id] = nil; end
 946                                         if not next(self.active) then return nil; end
 947                                 else
 948                                         --print('retry', o.server, o.delay);
 949                                         local _a = self.socket[o.server];
 950                                         if _a then _a:send(o.packet); end
 951                                         o.retry = self.time + self.delays[o.delay];
 952                                 end
 953                         end
 954                 end
 955         end
 956
 957         if next(self.active) then return true; end
 958         return nil;
 959 end
 960
 961
 962 function resolver:lookup(qname, qtype, qclass)    -- - - - - - - - - -  lookup
 963         self:query (qname, qtype, qclass)
 964         while self:pulse() do
 965                 local recvt = {}
 966                 for i, s in ipairs(self.socket) do
 967                         recvt[i] = s
 968                 end
 969                 socket.select(recvt, nil, 4)
 970         end
 971         --print(self.cache);
 972         return self:peek(qname, qtype, qclass);
 973 end
 974
 975 function resolver:lookupex(handler, qname, qtype, qclass)    -- - - - - - - - - -  lookup
 976         return self:peek(qname, qtype, qclass) or self:query(qname, qtype, qclass);
 977 end
 978
 979 function resolver:tohostname(ip)
 980         return dns.lookup(ip:gsub("(%d+)%.(%d+)%.(%d+)%.(%d+)", "%4.%3.%2.%1.in-addr.arpa."), "PTR");
 981 end
 982
 983 --print ---------------------------------------------------------------- print
 984
 985
 986 local hints = {    -- - - - - - - - - - - - - - - - - - - - - - - - - - - hints
 987         qr = { [0]='query', 'response' },
 988         opcode = { [0]='query', 'inverse query', 'server status request' },
 989         aa = { [0]='non-authoritative', 'authoritative' },
 990         tc = { [0]='complete', 'truncated' },
 991         rd = { [0]='recursion not desired', 'recursion desired' },
 992         ra = { [0]='recursion not available', 'recursion available' },
 993         z  = { [0]='(reserved)' },
 994         rcode = { [0]='no error', 'format error', 'server failure', 'name error', 'not implemented' },
 995
 996         type = dns.type,
 997         class = dns.class
 998 };
 999
1000
1001 local function hint(p, s)    -- - - - - - - - - - - - - - - - - - - - - - hint
1002         return (hints[s] and hints[s][p[s]]) or '';
1003 end
1004
1005
1006 function resolver.print(response)    -- - - - - - - - - - - - - resolver.print
1007         for s,s in pairs { 'id', 'qr', 'opcode', 'aa', 'tc', 'rd', 'ra', 'z',
1008                                                 'rcode', 'qdcount', 'ancount', 'nscount', 'arcount' } do
1009                 print( string.format('%-30s', 'header.'..s), response.header[s], hint(response.header, s) );
1010         end
1011
1012         for i,question in ipairs(response.question) do
1013                 print(string.format ('question[%i].name         ', i), question.name);
1014                 print(string.format ('question[%i].type         ', i), question.type);
1015                 print(string.format ('question[%i].class        ', i), question.class);
1016         end
1017
1018         local common = { name=1, type=1, class=1, ttl=1, rdlength=1, rdata=1 };
1019         local tmp;
1020         for s,s in pairs({'answer', 'authority', 'additional'}) do
1021                 for i,rr in pairs(response[s]) do
1022                         for j,t in pairs({ 'name', 'type', 'class', 'ttl', 'rdlength' }) do
1023                                 tmp = string.format('%s[%i].%s', s, i, t);
1024                                 print(string.format('%-30s', tmp), rr[t], hint(rr, t));
1025                         end
1026                         for j,t in pairs(rr) do
1027                                 if not common[j] then
1028                                         tmp = string.format('%s[%i].%s', s, i, j);
1029                                         print(string.format('%-30s  %s', tostring(tmp), tostring(t)));
1030                                 end
1031                         end
1032                 end
1033         end
1034 end
1035
1036
1037 -- module api ------------------------------------------------------ module api
1038
1039
1040 function dns.resolver ()    -- - - - - - - - - - - - - - - - - - - - - resolver
1041         -- this function seems to be redundant with resolver.new ()
1042
1043         local r = { active = {}, cache = {}, unsorted = {}, wanted = {}, best_server = 1 };
1044         setmetatable (r, resolver);
1045         setmetatable (r.cache, cache_metatable);
1046         setmetatable (r.unsorted, { __mode = 'kv' });
1047         return r;
1048 end
1049
1050 local _resolver = dns.resolver();
1051 dns._resolver = _resolver;
1052
1053 function dns.lookup(...)    -- - - - - - - - - - - - - - - - - - - - -  lookup
1054         return _resolver:lookup(...);
1055 end
1056
1057 function dns.tohostname(...)
1058         return _resolver:tohostname(...);
1059 end
1060
1061 function dns.purge(...)    -- - - - - - - - - - - - - - - - - - - - - -  purge
1062         return _resolver:purge(...);
1063 end
1064
1065 function dns.peek(...)    -- - - - - - - - - - - - - - - - - - - - - - -  peek
1066         return _resolver:peek(...);
1067 end
1068
1069 function dns.query(...)    -- - - - - - - - - - - - - - - - - - - - - -  query
1070         return _resolver:query(...);
1071 end
1072
1073 function dns.feed(...)    -- - - - - - - - - - - - - - - - - - - - - - -  feed
1074         return _resolver:feed(...);
1075 end
1076
1077 function dns.cancel(...)  -- - - - - - - - - - - - - - - - - - - - - -  cancel
1078         return _resolver:cancel(...);
1079 end
1080
1081 function dns.settimeout(...)
1082         return _resolver:settimeout(...);
1083 end
1084
1085 function dns.cache()
1086         return _resolver.cache;
1087 end
1088
1089 function dns.socket_wrapper_set(...)    -- - - - - - - - -  socket_wrapper_set
1090         return _resolver:socket_wrapper_set(...);
1091 end
1092
1093 return dns;