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 local new_ip = require "util.ip".new_ip;
  18
  19 local _, windows = pcall(require, "util.windows");
  20 local is_windows = (_ and windows) or os.getenv("WINDIR");
  21
  22 local coroutine, io, math, string, table =
  23       coroutine, io, math, string, table;
  24
  25 local ipairs, next, pairs, print, setmetatable, tostring, assert, error, unpack, select, type=
  26       ipairs, next, pairs, print, setmetatable, tostring, assert, error, unpack, select, type;
  27
  28 local ztact = { -- public domain 20080404 lua@ztact.com
  29         get = function(parent, ...)
  30                 local len = select('#', ...);
  31                 for i=1,len do
  32                         parent = parent[select(i, ...)];
  33                         if parent == nil then break; end
  34                 end
  35                 return parent;
  36         end;
  37         set = function(parent, ...)
  38                 local len = select('#', ...);
  39                 local key, value = select(len-1, ...);
  40                 local cutpoint, cutkey;
  41
  42                 for i=1,len-2 do
  43                         local key = select (i, ...)
  44                         local child = parent[key]
  45
  46                         if value == nil then
  47                                 if child == nil then
  48                                         return;
  49                                 elseif next(child, next(child)) then
  50                                         cutpoint = nil; cutkey = nil;
  51                                 elseif cutpoint == nil then
  52                                         cutpoint = parent; cutkey = key;
  53                                 end
  54                         elseif child == nil then
  55                                 child = {};
  56                                 parent[key] = child;
  57                         end
  58                         parent = child
  59                 end
  60
  61                 if value == nil and cutpoint then
  62                         cutpoint[cutkey] = nil;
  63                 else
  64                         parent[key] = value;
  65                         return value;
  66                 end
  67         end;
  68 };
  69 local get, set = ztact.get, ztact.set;
  70
  71 local default_timeout = 15;
  72
  73 -------------------------------------------------- module dns
  74 module('dns')
  75 local dns = _M;
  76
  77
  78 -- dns type & class codes ------------------------------ dns type & class codes
  79
  80
  81 local append = table.insert
  82
  83
  84 local function highbyte(i)    -- - - - - - - - - - - - - - - - - - -  highbyte
  85         return (i-(i%0x100))/0x100;
  86 end
  87
  88
  89 local function augment (t)    -- - - - - - - - - - - - - - - - - - - -  augment
  90         local a = {};
  91         for i,s in pairs(t) do
  92                 a[i] = s;
  93                 a[s] = s;
  94                 a[string.lower(s)] = s;
  95         end
  96         return a;
  97 end
  98
  99
 100 local function encode (t)    -- - - - - - - - - - - - - - - - - - - - -  encode
 101         local code = {};
 102         for i,s in pairs(t) do
 103                 local word = string.char(highbyte(i), i%0x100);
 104                 code[i] = word;
 105                 code[s] = word;
 106                 code[string.lower(s)] = word;
 107         end
 108         return code;
 109 end
 110
 111
 112 dns.types = {
 113         'A', 'NS', 'MD', 'MF', 'CNAME', 'SOA', 'MB', 'MG', 'MR', 'NULL', 'WKS',
 114         'PTR', 'HINFO', 'MINFO', 'MX', 'TXT',
 115         [ 28] = 'AAAA', [ 29] = 'LOC',   [ 33] = 'SRV',
 116         [252] = 'AXFR', [253] = 'MAILB', [254] = 'MAILA', [255] = '*' };
 117
 118
 119 dns.classes = { 'IN', 'CS', 'CH', 'HS', [255] = '*' };
 120
 121
 122 dns.type      = augment (dns.types);
 123 dns.class     = augment (dns.classes);
 124 dns.typecode  = encode  (dns.types);
 125 dns.classcode = encode  (dns.classes);
 126
 127
 128
 129 local function standardize(qname, qtype, qclass)    -- - - - - - - standardize
 130         if string.byte(qname, -1) ~= 0x2E then qname = qname..'.';  end
 131         qname = string.lower(qname);
 132         return qname, dns.type[qtype or 'A'], dns.class[qclass or 'IN'];
 133 end
 134
 135
 136 local function prune(rrs, time, soft)    -- - - - - - - - - - - - - - -  prune
 137         time = time or socket.gettime();
 138         for i,rr in ipairs(rrs) do
 139                 if rr.tod then
 140                         -- rr.tod = rr.tod - 50    -- accelerated decripitude
 141                         rr.ttl = math.floor(rr.tod - time);
 142                         if rr.ttl <= 0 then
 143                                 rrs[rr[rr.type:lower()]] = nil;
 144                                 table.remove(rrs, i);
 145                                 return prune(rrs, time, soft); -- Re-iterate
 146                         end
 147                 elseif soft == 'soft' then    -- What is this?  I forget!
 148                         assert(rr.ttl == 0);
 149                         rrs[rr[rr.type:lower()]] = nil;
 150                         table.remove(rrs, i);
 151                 end
 152         end
 153 end
 154
 155
 156 -- metatables & co. ------------------------------------------ metatables & co.
 157
 158
 159 local resolver = {};
 160 resolver.__index = resolver;
 161
 162 resolver.timeout = default_timeout;
 163
 164 local function default_rr_tostring(rr)
 165         local rr_val = rr.type and rr[rr.type:lower()];
 166         if type(rr_val) ~= "string" then
 167                 return "<UNKNOWN RDATA TYPE>";
 168         end
 169         return rr_val;
 170 end
 171
 172 local special_tostrings = {
 173         LOC = resolver.LOC_tostring;
 174         MX  = function (rr)
 175                 return string.format('%2i %s', rr.pref, rr.mx);
 176         end;
 177         SRV = function (rr)
 178                 local s = rr.srv;
 179                 return string.format('%5d %5d %5d %s', s.priority, s.weight, s.port, s.target);
 180         end;
 181 };
 182
 183 local rr_metatable = {};   -- - - - - - - - - - - - - - - - - - -  rr_metatable
 184 function rr_metatable.__tostring(rr)
 185         local rr_string = (special_tostrings[rr.type] or default_rr_tostring)(rr);
 186         return string.format('%2s %-5s %6i %-28s %s', rr.class, rr.type, rr.ttl, rr.name, rr_string);
 187 end
 188
 189
 190 local rrs_metatable = {};    -- - - - - - - - - - - - - - - - - -  rrs_metatable
 191 function rrs_metatable.__tostring(rrs)
 192         local t = {};
 193         for i,rr in ipairs(rrs) do
 194                 append(t, tostring(rr)..'\n');
 195         end
 196         return table.concat(t);
 197 end
 198
 199
 200 local cache_metatable = {};    -- - - - - - - - - - - - - - - -  cache_metatable
 201 function cache_metatable.__tostring(cache)
 202         local time = socket.gettime();
 203         local t = {};
 204         for class,types in pairs(cache) do
 205                 for type,names in pairs(types) do
 206                         for name,rrs in pairs(names) do
 207                                 prune(rrs, time);
 208                                 append(t, tostring(rrs));
 209                         end
 210                 end
 211         end
 212         return table.concat(t);
 213 end
 214
 215
 216 function resolver:new()    -- - - - - - - - - - - - - - - - - - - - - resolver
 217         local r = { active = {}, cache = {}, unsorted = {} };
 218         setmetatable(r, resolver);
 219         setmetatable(r.cache, cache_metatable);
 220         setmetatable(r.unsorted, { __mode = 'kv' });
 221         return r;
 222 end
 223
 224
 225 -- packet layer -------------------------------------------------- packet layer
 226
 227
 228 function dns.random(...)    -- - - - - - - - - - - - - - - - - - -  dns.random
 229         math.randomseed(math.floor(10000*socket.gettime()) % 0x100000000);
 230         dns.random = math.random;
 231         return dns.random(...);
 232 end
 233
 234
 235 local function encodeHeader(o)    -- - - - - - - - - - - - - - -  encodeHeader
 236         o = o or {};
 237         o.id = o.id or dns.random(0, 0xffff); -- 16b    (random) id
 238
 239         o.rd = o.rd or 1;               --  1b  1 recursion desired
 240         o.tc = o.tc or 0;               --  1b  1 truncated response
 241         o.aa = o.aa or 0;               --  1b  1 authoritative response
 242         o.opcode = o.opcode or 0;       --  4b  0 query
 243                                 --  1 inverse query
 244                                 --      2 server status request
 245                                 --      3-15 reserved
 246         o.qr = o.qr or 0;               --  1b  0 query, 1 response
 247
 248         o.rcode = o.rcode or 0; --  4b  0 no error
 249                                 --      1 format error
 250                                 --      2 server failure
 251                                 --      3 name error
 252                                 --      4 not implemented
 253                                 --      5 refused
 254                                 --      6-15 reserved
 255         o.z = o.z  or 0;                --  3b  0 resvered
 256         o.ra = o.ra or 0;               --  1b  1 recursion available
 257
 258         o.qdcount = o.qdcount or 1;     -- 16b  number of question RRs
 259         o.ancount = o.ancount or 0;     -- 16b  number of answers RRs
 260         o.nscount = o.nscount or 0;     -- 16b  number of nameservers RRs
 261         o.arcount = o.arcount or 0;     -- 16b  number of additional RRs
 262
 263         -- string.char() rounds, so prevent roundup with -0.4999
 264         local header = string.char(
 265                 highbyte(o.id), o.id %0x100,
 266                 o.rd + 2*o.tc + 4*o.aa + 8*o.opcode + 128*o.qr,
 267                 o.rcode + 16*o.z + 128*o.ra,
 268                 highbyte(o.qdcount),  o.qdcount %0x100,
 269                 highbyte(o.ancount),  o.ancount %0x100,
 270                 highbyte(o.nscount),  o.nscount %0x100,
 271                 highbyte(o.arcount),  o.arcount %0x100
 272         );
 273
 274         return header, o.id;
 275 end
 276
 277
 278 local function encodeName(name)    -- - - - - - - - - - - - - - - - encodeName
 279         local t = {};
 280         for part in string.gmatch(name, '[^.]+') do
 281                 append(t, string.char(string.len(part)));
 282                 append(t, part);
 283         end
 284         append(t, string.char(0));
 285         return table.concat(t);
 286 end
 287
 288
 289 local function encodeQuestion(qname, qtype, qclass)    -- - - - encodeQuestion
 290         qname  = encodeName(qname);
 291         qtype  = dns.typecode[qtype or 'a'];
 292         qclass = dns.classcode[qclass or 'in'];
 293         return qname..qtype..qclass;
 294 end
 295
 296
 297 function resolver:byte(len)    -- - - - - - - - - - - - - - - - - - - - - byte
 298         len = len or 1;
 299         local offset = self.offset;
 300         local last = offset + len - 1;
 301         if last > #self.packet then
 302                 error(string.format('out of bounds: %i>%i', last, #self.packet));
 303         end
 304         self.offset = offset + len;
 305         return string.byte(self.packet, offset, last);
 306 end
 307
 308
 309 function resolver:word()    -- - - - - - - - - - - - - - - - - - - - - -  word
 310         local b1, b2 = self:byte(2);
 311         return 0x100*b1 + b2;
 312 end
 313
 314
 315 function resolver:dword ()    -- - - - - - - - - - - - - - - - - - - - -  dword
 316         local b1, b2, b3, b4 = self:byte(4);
 317         --print('dword', b1, b2, b3, b4);
 318         return 0x1000000*b1 + 0x10000*b2 + 0x100*b3 + b4;
 319 end
 320
 321
 322 function resolver:sub(len)    -- - - - - - - - - - - - - - - - - - - - - - sub
 323         len = len or 1;
 324         local s = string.sub(self.packet, self.offset, self.offset + len - 1);
 325         self.offset = self.offset + len;
 326         return s;
 327 end
 328
 329
 330 function resolver:header(force)    -- - - - - - - - - - - - - - - - - - header
 331         local id = self:word();
 332         --print(string.format(':header  id  %x', id));
 333         if not self.active[id] and not force then return nil; end
 334
 335         local h = { id = id };
 336
 337         local b1, b2 = self:byte(2);
 338
 339         h.rd      = b1 %2;
 340         h.tc      = b1 /2%2;
 341         h.aa      = b1 /4%2;
 342         h.opcode  = b1 /8%16;
 343         h.qr      = b1 /128;
 344
 345         h.rcode   = b2 %16;
 346         h.z       = b2 /16%8;
 347         h.ra      = b2 /128;
 348
 349         h.qdcount = self:word();
 350         h.ancount = self:word();
 351         h.nscount = self:word();
 352         h.arcount = self:word();
 353
 354         for k,v in pairs(h) do h[k] = v-v%1; end
 355
 356         return h;
 357 end
 358
 359
 360 function resolver:name()    -- - - - - - - - - - - - - - - - - - - - - -  name
 361         local remember, pointers = nil, 0;
 362         local len = self:byte();
 363         local n = {};
 364         if len == 0 then return "." end -- Root label
 365         while len > 0 do
 366                 if len >= 0xc0 then    -- name is "compressed"
 367                         pointers = pointers + 1;
 368                         if pointers >= 20 then error('dns error: 20 pointers'); end;
 369                         local offset = ((len-0xc0)*0x100) + self:byte();
 370                         remember = remember or self.offset;
 371                         self.offset = offset + 1;    -- +1 for lua
 372                 else    -- name is not compressed
 373                         append(n, self:sub(len)..'.');
 374                 end
 375                 len = self:byte();
 376         end
 377         self.offset = remember or self.offset;
 378         return table.concat(n);
 379 end
 380
 381
 382 function resolver:question()    -- - - - - - - - - - - - - - - - - -  question
 383         local q = {};
 384         q.name  = self:name();
 385         q.type  = dns.type[self:word()];
 386         q.class = dns.class[self:word()];
 387         return q;
 388 end
 389
 390
 391 function resolver:A(rr)    -- - - - - - - - - - - - - - - - - - - - - - - -  A
 392         local b1, b2, b3, b4 = self:byte(4);
 393         rr.a = string.format('%i.%i.%i.%i', b1, b2, b3, b4);
 394 end
 395
 396 function resolver:AAAA(rr)
 397         local addr = {};
 398         for i = 1, rr.rdlength, 2 do
 399                 local b1, b2 = self:byte(2);
 400                 table.insert(addr, ("%02x%02x"):format(b1, b2));
 401         end
 402         addr = table.concat(addr, ":"):gsub("%f[%x]0+(%x)","%1");
 403         local zeros = {};
 404         for item in addr:gmatch(":[0:]+:") do
 405                 table.insert(zeros, item)
 406         end
 407         if #zeros == 0 then
 408                 rr.aaaa = addr;
 409                 return
 410         elseif #zeros > 1 then
 411                 table.sort(zeros, function(a, b) return #a > #b end);
 412         end
 413         rr.aaaa = addr:gsub(zeros[1], "::", 1):gsub("^0::", "::"):gsub("::0$", "::");
 414 end
 415
 416 function resolver:CNAME(rr)    -- - - - - - - - - - - - - - - - - - - -  CNAME
 417         rr.cname = self:name();
 418 end
 419
 420
 421 function resolver:MX(rr)    -- - - - - - - - - - - - - - - - - - - - - - -  MX
 422         rr.pref = self:word();
 423         rr.mx   = self:name();
 424 end
 425
 426
 427 function resolver:LOC_nibble_power()    -- - - - - - - - - -  LOC_nibble_power
 428         local b = self:byte();
 429         --print('nibbles', ((b-(b%0x10))/0x10), (b%0x10));
 430         return ((b-(b%0x10))/0x10) * (10^(b%0x10));
 431 end
 432
 433
 434 function resolver:LOC(rr)    -- - - - - - - - - - - - - - - - - - - - - -  LOC
 435         rr.version = self:byte();
 436         if rr.version == 0 then
 437                 rr.loc           = rr.loc or {};
 438                 rr.loc.size      = self:LOC_nibble_power();
 439                 rr.loc.horiz_pre = self:LOC_nibble_power();
 440                 rr.loc.vert_pre  = self:LOC_nibble_power();
 441                 rr.loc.latitude  = self:dword();
 442                 rr.loc.longitude = self:dword();
 443                 rr.loc.altitude  = self:dword();
 444         end
 445 end
 446
 447
 448 local function LOC_tostring_degrees(f, pos, neg)    -- - - - - - - - - - - - -
 449         f = f - 0x80000000;
 450         if f < 0 then pos = neg; f = -f; end
 451         local deg, min, msec;
 452         msec = f%60000;
 453         f    = (f-msec)/60000;
 454         min  = f%60;
 455         deg = (f-min)/60;
 456         return string.format('%3d %2d %2.3f %s', deg, min, msec/1000, pos);
 457 end
 458
 459
 460 function resolver.LOC_tostring(rr)    -- - - - - - - - - - - - -  LOC_tostring
 461         local t = {};
 462
 463         --[[
 464         for k,name in pairs { 'size', 'horiz_pre', 'vert_pre', 'latitude', 'longitude', 'altitude' } do
 465                 append(t, string.format('%4s%-10s: %12.0f\n', '', name, rr.loc[name]));
 466         end
 467         --]]
 468
 469         append(t, string.format(
 470                 '%s    %s    %.2fm %.2fm %.2fm %.2fm',
 471                 LOC_tostring_degrees (rr.loc.latitude, 'N', 'S'),
 472                 LOC_tostring_degrees (rr.loc.longitude, 'E', 'W'),
 473                 (rr.loc.altitude - 10000000) / 100,
 474                 rr.loc.size / 100,
 475                 rr.loc.horiz_pre / 100,
 476                 rr.loc.vert_pre / 100
 477         ));
 478
 479         return table.concat(t);
 480 end
 481
 482
 483 function resolver:NS(rr)    -- - - - - - - - - - - - - - - - - - - - - - -  NS
 484         rr.ns = self:name();
 485 end
 486
 487
 488 function resolver:SOA(rr)    -- - - - - - - - - - - - - - - - - - - - - -  SOA
 489 end
 490
 491
 492 function resolver:SRV(rr)    -- - - - - - - - - - - - - - - - - - - - - -  SRV
 493           rr.srv = {};
 494           rr.srv.priority = self:word();
 495           rr.srv.weight   = self:word();
 496           rr.srv.port     = self:word();
 497           rr.srv.target   = self:name();
 498 end
 499
 500 function resolver:PTR(rr)
 501         rr.ptr = self:name();
 502 end
 503
 504 function resolver:TXT(rr)    -- - - - - - - - - - - - - - - - - - - - - -  TXT
 505         rr.txt = self:sub (self:byte());
 506 end
 507
 508
 509 function resolver:rr()    -- - - - - - - - - - - - - - - - - - - - - - - -  rr
 510         local rr = {};
 511         setmetatable(rr, rr_metatable);
 512         rr.name     = self:name(self);
 513         rr.type     = dns.type[self:word()] or rr.type;
 514         rr.class    = dns.class[self:word()] or rr.class;
 515         rr.ttl      = 0x10000*self:word() + self:word();
 516         rr.rdlength = self:word();
 517
 518         if rr.ttl <= 0 then
 519                 rr.tod = self.time + 30;
 520         else
 521                 rr.tod = self.time + rr.ttl;
 522         end
 523
 524         local remember = self.offset;
 525         local rr_parser = self[dns.type[rr.type]];
 526         if rr_parser then rr_parser(self, rr); end
 527         self.offset = remember;
 528         rr.rdata = self:sub(rr.rdlength);
 529         return rr;
 530 end
 531
 532
 533 function resolver:rrs (count)    -- - - - - - - - - - - - - - - - - - - - - rrs
 534         local rrs = {};
 535         for i = 1,count do append(rrs, self:rr()); end
 536         return rrs;
 537 end
 538
 539
 540 function resolver:decode(packet, force)    -- - - - - - - - - - - - - - decode
 541         self.packet, self.offset = packet, 1;
 542         local header = self:header(force);
 543         if not header then return nil; end
 544         local response = { header = header };
 545
 546         response.question = {};
 547         local offset = self.offset;
 548         for i = 1,response.header.qdcount do
 549                 append(response.question, self:question());
 550         end
 551         response.question.raw = string.sub(self.packet, offset, self.offset - 1);
 552
 553         if not force then
 554                 if not self.active[response.header.id] or not self.active[response.header.id][response.question.raw] then
 555                         self.active[response.header.id] = nil;
 556                         return nil;
 557                 end
 558         end
 559
 560         response.answer     = self:rrs(response.header.ancount);
 561         response.authority  = self:rrs(response.header.nscount);
 562         response.additional = self:rrs(response.header.arcount);
 563
 564         return response;
 565 end
 566
 567
 568 -- socket layer -------------------------------------------------- socket layer
 569
 570
 571 resolver.delays = { 1, 3 };
 572
 573
 574 function resolver:addnameserver(address)    -- - - - - - - - - - addnameserver
 575         self.server = self.server or {};
 576         append(self.server, address);
 577 end
 578
 579
 580 function resolver:setnameserver(address)    -- - - - - - - - - - setnameserver
 581         self.server = {};
 582         self:addnameserver(address);
 583 end
 584
 585
 586 function resolver:adddefaultnameservers()    -- - - - -  adddefaultnameservers
 587         if is_windows then
 588                 if windows and windows.get_nameservers then
 589                         for _, server in ipairs(windows.get_nameservers()) do
 590                                 self:addnameserver(server);
 591                         end
 592                 end
 593                 if not self.server or #self.server == 0 then
 594                         -- TODO log warning about no nameservers, adding opendns servers as fallback
 595                         self:addnameserver("208.67.222.222");
 596                         self:addnameserver("208.67.220.220");
 597                 end
 598         else -- posix
 599                 local resolv_conf = io.open("/etc/resolv.conf");
 600                 if resolv_conf then
 601                         for line in resolv_conf:lines() do
 602                                 line = line:gsub("#.*$", "")
 603                                         :match('^%s*nameserver%s+([%x:%.]*)%s*$');
 604                                 if line then
 605                                         local ip = new_ip(line);
 606                                         if ip then
 607                                                 self:addnameserver(ip.addr);
 608                                         end
 609                                 end
 610                         end
 611                 end
 612                 if not self.server or #self.server == 0 then
 613                         -- TODO log warning about no nameservers, adding localhost as the default nameserver
 614                         self:addnameserver("127.0.0.1");
 615                 end
 616         end
 617 end
 618
 619
 620 function resolver:getsocket(servernum)    -- - - - - - - - - - - - - getsocket
 621         self.socket = self.socket or {};
 622         self.socketset = self.socketset or {};
 623
 624         local sock = self.socket[servernum];
 625         if sock then return sock; end
 626
 627         local ok, err;
 628         local peer = self.server[servernum];
 629         if peer:find(":") then
 630                 sock, err = socket.udp6();
 631         else
 632                 sock, err = socket.udp();
 633         end
 634         if sock and self.socket_wrapper then sock, err = self.socket_wrapper(sock, self); end
 635         if not sock then
 636                 return nil, err;
 637         end
 638         sock:settimeout(0);
 639         -- todo: attempt to use a random port, fallback to 0
 640         self.socket[servernum] = sock;
 641         self.socketset[sock] = servernum;
 642         -- set{sock,peer}name can fail, eg because of local routing table
 643         -- if so, try the next server
 644         ok, err = sock:setsockname('*', 0);
 645         if not ok then return self:servfail(sock, err); end
 646         ok, err = sock:setpeername(peer, 53);
 647         if not ok then return self:servfail(sock, err); end
 648         return sock;
 649 end
 650
 651 function resolver:voidsocket(sock)
 652         if self.socket[sock] then
 653                 self.socketset[self.socket[sock]] = nil;
 654                 self.socket[sock] = nil;
 655         elseif self.socketset[sock] then
 656                 self.socket[self.socketset[sock]] = nil;
 657                 self.socketset[sock] = nil;
 658         end
 659         sock:close();
 660 end
 661
 662 function resolver:socket_wrapper_set(func)  -- - - - - - - socket_wrapper_set
 663         self.socket_wrapper = func;
 664 end
 665
 666
 667 function resolver:closeall ()    -- - - - - - - - - - - - - - - - - -  closeall
 668         for i,sock in ipairs(self.socket) do
 669                 self.socket[i] = nil;
 670                 self.socketset[sock] = nil;
 671                 sock:close();
 672         end
 673 end
 674
 675
 676 function resolver:remember(rr, type)    -- - - - - - - - - - - - - -  remember
 677         --print ('remember', type, rr.class, rr.type, rr.name)
 678         local qname, qtype, qclass = standardize(rr.name, rr.type, rr.class);
 679
 680         if type ~= '*' then
 681                 type = qtype;
 682                 local all = get(self.cache, qclass, '*', qname);
 683                 --print('remember all', all);
 684                 if all then append(all, rr); end
 685         end
 686
 687         self.cache = self.cache or setmetatable({}, cache_metatable);
 688         local rrs = get(self.cache, qclass, type, qname) or
 689                 set(self.cache, qclass, type, qname, setmetatable({}, rrs_metatable));
 690         if not rrs[rr[qtype:lower()]] then
 691                 rrs[rr[qtype:lower()]] = true;
 692                 append(rrs, rr);
 693         end
 694
 695         if type == 'MX' then self.unsorted[rrs] = true; end
 696 end
 697
 698
 699 local function comp_mx(a, b)    -- - - - - - - - - - - - - - - - - - - comp_mx
 700         return (a.pref == b.pref) and (a.mx < b.mx) or (a.pref < b.pref);
 701 end
 702
 703
 704 function resolver:peek (qname, qtype, qclass)    -- - - - - - - - - - - -  peek
 705         qname, qtype, qclass = standardize(qname, qtype, qclass);
 706         local rrs = get(self.cache, qclass, qtype, qname);
 707         if not rrs then return nil; end
 708         if prune(rrs, socket.gettime()) and qtype == '*' or not next(rrs) then
 709                 set(self.cache, qclass, qtype, qname, nil);
 710                 return nil;
 711         end
 712         if self.unsorted[rrs] then table.sort (rrs, comp_mx); end
 713         return rrs;
 714 end
 715
 716
 717 function resolver:purge(soft)    -- - - - - - - - - - - - - - - - - - -  purge
 718         if soft == 'soft' then
 719                 self.time = socket.gettime();
 720                 for class,types in pairs(self.cache or {}) do
 721                         for type,names in pairs(types) do
 722                                 for name,rrs in pairs(names) do
 723                                         prune(rrs, self.time, 'soft')
 724                                 end
 725                         end
 726                 end
 727         else self.cache = setmetatable({}, cache_metatable); end
 728 end
 729
 730
 731 function resolver:query(qname, qtype, qclass)    -- - - - - - - - - - -- query
 732         qname, qtype, qclass = standardize(qname, qtype, qclass)
 733
 734         local co = coroutine.running();
 735         local q = get(self.wanted, qclass, qtype, qname);
 736         if co and q then
 737                 -- We are already waiting for a reply to an identical query.
 738                 set(self.wanted, qclass, qtype, qname, co, true);
 739                 return true;
 740         end
 741
 742         if not self.server then self:adddefaultnameservers(); end
 743
 744         local question = encodeQuestion(qname, qtype, qclass);
 745         local peek = self:peek (qname, qtype, qclass);
 746         if peek then return peek; end
 747
 748         local header, id = encodeHeader();
 749         --print ('query  id', id, qclass, qtype, qname)
 750         local o = {
 751                 packet = header..question,
 752                 server = self.best_server,
 753                 delay  = 1,
 754                 retry  = socket.gettime() + self.delays[1]
 755         };
 756
 757         -- remember the query
 758         self.active[id] = self.active[id] or {};
 759         self.active[id][question] = o;
 760
 761         -- remember which coroutine wants the answer
 762         if co then
 763                 set(self.wanted, qclass, qtype, qname, co, true);
 764         end
 765
 766         local conn, err = self:getsocket(o.server)
 767         if not conn then
 768                 return nil, err;
 769         end
 770         conn:send (o.packet)
 771
 772         if timer and self.timeout then
 773                 local num_servers = #self.server;
 774                 local i = 1;
 775                 timer.add_task(self.timeout, function ()
 776                         if get(self.wanted, qclass, qtype, qname, co) then
 777                                 if i < num_servers then
 778                                         i = i + 1;
 779                                         self:servfail(conn);
 780                                         o.server = self.best_server;
 781                                         conn, err = self:getsocket(o.server);
 782                                         if conn then
 783                                                 conn:send(o.packet);
 784                                                 return self.timeout;
 785                                         end
 786                                 end
 787                                 -- Tried everything, failed
 788                                 self:cancel(qclass, qtype, qname);
 789                         end
 790                 end)
 791         end
 792         return true;
 793 end
 794
 795 function resolver:servfail(sock, err)
 796         -- Resend all queries for this server
 797
 798         local num = self.socketset[sock]
 799
 800         -- Socket is dead now
 801         sock = self:voidsocket(sock);
 802
 803         -- Find all requests to the down server, and retry on the next server
 804         self.time = socket.gettime();
 805         for id,queries in pairs(self.active) do
 806                 for question,o in pairs(queries) do
 807                         if o.server == num then -- This request was to the broken server
 808                                 o.server = o.server + 1 -- Use next server
 809                                 if o.server > #self.server then
 810                                         o.server = 1;
 811                                 end
 812
 813                                 o.retries = (o.retries or 0) + 1;
 814                                 if o.retries >= #self.server then
 815                                         --print('timeout');
 816                                         queries[question] = nil;
 817                                 else
 818                                         sock, err = self:getsocket(o.server);
 819                                         if sock then sock:send(o.packet); end
 820                                 end
 821                         end
 822                 end
 823                 if next(queries) == nil then
 824                         self.active[id] = nil;
 825                 end
 826         end
 827
 828         if num == self.best_server then
 829                 self.best_server = self.best_server + 1;
 830                 if self.best_server > #self.server then
 831                         -- Exhausted all servers, try first again
 832                         self.best_server = 1;
 833                 end
 834         end
 835         return sock, err;
 836 end
 837
 838 function resolver:settimeout(seconds)
 839         self.timeout = seconds;
 840 end
 841
 842 function resolver:receive(rset)    -- - - - - - - - - - - - - - - - -  receive
 843         --print('receive');  print(self.socket);
 844         self.time = socket.gettime();
 845         rset = rset or self.socket;
 846
 847         local response;
 848         for i,sock in pairs(rset) do
 849
 850                 if self.socketset[sock] then
 851                         local packet = sock:receive();
 852                         if packet then
 853                                 response = self:decode(packet);
 854                                 if response and self.active[response.header.id]
 855                                         and self.active[response.header.id][response.question.raw] then
 856                                         --print('received response');
 857                                         --self.print(response);
 858
 859                                         for j,rr in pairs(response.answer) do
 860                                                 if rr.name:sub(-#response.question[1].name, -1) == response.question[1].name then
 861                                                         self:remember(rr, response.question[1].type)
 862                                                 end
 863                                         end
 864
 865                                         -- retire the query
 866                                         local queries = self.active[response.header.id];
 867                                         queries[response.question.raw] = nil;
 868
 869                                         if not next(queries) then self.active[response.header.id] = nil; end
 870                                         if not next(self.active) then self:closeall(); end
 871
 872                                         -- was the query on the wanted list?
 873                                         local q = response.question[1];
 874                                         local cos = get(self.wanted, q.class, q.type, q.name);
 875                                         if cos then
 876                                                 for co in pairs(cos) do
 877                                                         if coroutine.status(co) == "suspended" then coroutine.resume(co); end
 878                                                 end
 879                                                 set(self.wanted, q.class, q.type, q.name, nil);
 880                                         end
 881                                 end
 882
 883                         end
 884                 end
 885         end
 886
 887         return response;
 888 end
 889
 890
 891 function resolver:feed(sock, packet, force)
 892         --print('receive'); print(self.socket);
 893         self.time = socket.gettime();
 894
 895         local response = self:decode(packet, force);
 896         if response and self.active[response.header.id]
 897                 and self.active[response.header.id][response.question.raw] then
 898                 --print('received response');
 899                 --self.print(response);
 900
 901                 for j,rr in pairs(response.answer) do
 902                         self:remember(rr, response.question[1].type);
 903                 end
 904
 905                 -- retire the query
 906                 local queries = self.active[response.header.id];
 907                 queries[response.question.raw] = nil;
 908                 if not next(queries) then self.active[response.header.id] = nil; end
 909                 if not next(self.active) then self:closeall(); end
 910
 911                 -- was the query on the wanted list?
 912                 local q = response.question[1];
 913                 if q then
 914                         local cos = get(self.wanted, q.class, q.type, q.name);
 915                         if cos then
 916                                 for co in pairs(cos) do
 917                                         if coroutine.status(co) == "suspended" then coroutine.resume(co); end
 918                                 end
 919                                 set(self.wanted, q.class, q.type, q.name, nil);
 920                         end
 921                 end
 922         end
 923
 924         return response;
 925 end
 926
 927 function resolver:cancel(qclass, qtype, qname)
 928         local cos = get(self.wanted, qclass, qtype, qname);
 929         if cos then
 930                 for co in pairs(cos) do
 931                         if coroutine.status(co) == "suspended" then coroutine.resume(co); end
 932                 end
 933                 set(self.wanted, qclass, qtype, qname, nil);
 934         end
 935 end
 936
 937 function resolver:pulse()    -- - - - - - - - - - - - - - - - - - - - -  pulse
 938         --print(':pulse');
 939         while self:receive() do end
 940         if not next(self.active) then return nil; end
 941
 942         self.time = socket.gettime();
 943         for id,queries in pairs(self.active) do
 944                 for question,o in pairs(queries) do
 945                         if self.time >= o.retry then
 946
 947                                 o.server = o.server + 1;
 948                                 if o.server > #self.server then
 949                                         o.server = 1;
 950                                         o.delay = o.delay + 1;
 951                                 end
 952
 953                                 if o.delay > #self.delays then
 954                                         --print('timeout');
 955                                         queries[question] = nil;
 956                                         if not next(queries) then self.active[id] = nil; end
 957                                         if not next(self.active) then return nil; end
 958                                 else
 959                                         --print('retry', o.server, o.delay);
 960                                         local _a = self.socket[o.server];
 961                                         if _a then _a:send(o.packet); end
 962                                         o.retry = self.time + self.delays[o.delay];
 963                                 end
 964                         end
 965                 end
 966         end
 967
 968         if next(self.active) then return true; end
 969         return nil;
 970 end
 971
 972
 973 function resolver:lookup(qname, qtype, qclass)    -- - - - - - - - - -  lookup
 974         self:query (qname, qtype, qclass)
 975         while self:pulse() do
 976                 local recvt = {}
 977                 for i, s in ipairs(self.socket) do
 978                         recvt[i] = s
 979                 end
 980                 socket.select(recvt, nil, 4)
 981         end
 982         --print(self.cache);
 983         return self:peek(qname, qtype, qclass);
 984 end
 985
 986 function resolver:lookupex(handler, qname, qtype, qclass)    -- - - - - - - - - -  lookup
 987         return self:peek(qname, qtype, qclass) or self:query(qname, qtype, qclass);
 988 end
 989
 990 function resolver:tohostname(ip)
 991         return dns.lookup(ip:gsub("(%d+)%.(%d+)%.(%d+)%.(%d+)", "%4.%3.%2.%1.in-addr.arpa."), "PTR");
 992 end
 993
 994 --print ---------------------------------------------------------------- print
 995
 996
 997 local hints = {    -- - - - - - - - - - - - - - - - - - - - - - - - - - - hints
 998         qr = { [0]='query', 'response' },
 999         opcode = { [0]='query', 'inverse query', 'server status request' },
1000         aa = { [0]='non-authoritative', 'authoritative' },
1001         tc = { [0]='complete', 'truncated' },
1002         rd = { [0]='recursion not desired', 'recursion desired' },
1003         ra = { [0]='recursion not available', 'recursion available' },
1004         z  = { [0]='(reserved)' },
1005         rcode = { [0]='no error', 'format error', 'server failure', 'name error', 'not implemented' },
1006
1007         type = dns.type,
1008         class = dns.class
1009 };
1010
1011
1012 local function hint(p, s)    -- - - - - - - - - - - - - - - - - - - - - - hint
1013         return (hints[s] and hints[s][p[s]]) or '';
1014 end
1015
1016
1017 function resolver.print(response)    -- - - - - - - - - - - - - resolver.print
1018         for s,s in pairs { 'id', 'qr', 'opcode', 'aa', 'tc', 'rd', 'ra', 'z',
1019                                                 'rcode', 'qdcount', 'ancount', 'nscount', 'arcount' } do
1020                 print( string.format('%-30s', 'header.'..s), response.header[s], hint(response.header, s) );
1021         end
1022
1023         for i,question in ipairs(response.question) do
1024                 print(string.format ('question[%i].name         ', i), question.name);
1025                 print(string.format ('question[%i].type         ', i), question.type);
1026                 print(string.format ('question[%i].class        ', i), question.class);
1027         end
1028
1029         local common = { name=1, type=1, class=1, ttl=1, rdlength=1, rdata=1 };
1030         local tmp;
1031         for s,s in pairs({'answer', 'authority', 'additional'}) do
1032                 for i,rr in pairs(response[s]) do
1033                         for j,t in pairs({ 'name', 'type', 'class', 'ttl', 'rdlength' }) do
1034                                 tmp = string.format('%s[%i].%s', s, i, t);
1035                                 print(string.format('%-30s', tmp), rr[t], hint(rr, t));
1036                         end
1037                         for j,t in pairs(rr) do
1038                                 if not common[j] then
1039                                         tmp = string.format('%s[%i].%s', s, i, j);
1040                                         print(string.format('%-30s  %s', tostring(tmp), tostring(t)));
1041                                 end
1042                         end
1043                 end
1044         end
1045 end
1046
1047
1048 -- module api ------------------------------------------------------ module api
1049
1050
1051 function dns.resolver ()    -- - - - - - - - - - - - - - - - - - - - - resolver
1052         -- this function seems to be redundant with resolver.new ()
1053
1054         local r = { active = {}, cache = {}, unsorted = {}, wanted = {}, best_server = 1 };
1055         setmetatable (r, resolver);
1056         setmetatable (r.cache, cache_metatable);
1057         setmetatable (r.unsorted, { __mode = 'kv' });
1058         return r;
1059 end
1060
1061 local _resolver = dns.resolver();
1062 dns._resolver = _resolver;
1063
1064 function dns.lookup(...)    -- - - - - - - - - - - - - - - - - - - - -  lookup
1065         return _resolver:lookup(...);
1066 end
1067
1068 function dns.tohostname(...)
1069         return _resolver:tohostname(...);
1070 end
1071
1072 function dns.purge(...)    -- - - - - - - - - - - - - - - - - - - - - -  purge
1073         return _resolver:purge(...);
1074 end
1075
1076 function dns.peek(...)    -- - - - - - - - - - - - - - - - - - - - - - -  peek
1077         return _resolver:peek(...);
1078 end
1079
1080 function dns.query(...)    -- - - - - - - - - - - - - - - - - - - - - -  query
1081         return _resolver:query(...);
1082 end
1083
1084 function dns.feed(...)    -- - - - - - - - - - - - - - - - - - - - - - -  feed
1085         return _resolver:feed(...);
1086 end
1087
1088 function dns.cancel(...)  -- - - - - - - - - - - - - - - - - - - - - -  cancel
1089         return _resolver:cancel(...);
1090 end
1091
1092 function dns.settimeout(...)
1093         return _resolver:settimeout(...);
1094 end
1095
1096 function dns.cache()
1097         return _resolver.cache;
1098 end
1099
1100 function dns.socket_wrapper_set(...)    -- - - - - - - - -  socket_wrapper_set
1101         return _resolver:socket_wrapper_set(...);
1102 end
1103
1104 return dns;