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 pairs(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                                 table.remove(rrs, i);
 143                                 return prune(rrs, time, soft); -- Re-iterate
 144                         end
 145                 elseif soft == 'soft' then    -- What is this?  I forget!
 146                         assert(rr.ttl == 0);
 147                         rrs[i] = nil;
 148                 end
 149         end
 150 end
 151
 152
 153 -- metatables & co. ------------------------------------------ metatables & co.
 154
 155
 156 local resolver = {};
 157 resolver.__index = resolver;
 158
 159 resolver.timeout = default_timeout;
 160
 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>";
 165         end
 166         return rr_val;
 167 end
 168
 169 local special_tostrings = {
 170         LOC = resolver.LOC_tostring;
 171         MX  = function (rr)
 172                 return string.format('%2i %s', rr.pref, rr.mx);
 173         end;
 174         SRV = function (rr)
 175                 local s = rr.srv;
 176                 return string.format('%5d %5d %5d %s', s.priority, s.weight, s.port, s.target);
 177         end;
 178 };
 179
 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);
 184 end
 185
 186
 187 local rrs_metatable = {};    -- - - - - - - - - - - - - - - - - -  rrs_metatable
 188 function rrs_metatable.__tostring(rrs)
 189         local t = {};
 190         for i,rr in pairs(rrs) do
 191                 append(t, tostring(rr)..'\n');
 192         end
 193         return table.concat(t);
 194 end
 195
 196
 197 local cache_metatable = {};    -- - - - - - - - - - - - - - - -  cache_metatable
 198 function cache_metatable.__tostring(cache)
 199         local time = socket.gettime();
 200         local t = {};
 201         for class,types in pairs(cache) do
 202                 for type,names in pairs(types) do
 203                         for name,rrs in pairs(names) do
 204                                 prune(rrs, time);
 205                                 append(t, tostring(rrs));
 206                         end
 207                 end
 208         end
 209         return table.concat(t);
 210 end
 211
 212
 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' });
 218         return r;
 219 end
 220
 221
 222 -- packet layer -------------------------------------------------- packet layer
 223
 224
 225 function dns.random(...)    -- - - - - - - - - - - - - - - - - - -  dns.random
 226         math.randomseed(math.floor(10000*socket.gettime()));
 227         dns.random = math.random;
 228         return dns.random(...);
 229 end
 230
 231
 232 local function encodeHeader(o)    -- - - - - - - - - - - - - - -  encodeHeader
 233         o = o or {};
 234         o.id = o.id or dns.random(0, 0xffff); -- 16b    (random) id
 235
 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
 240                                 --  1 inverse query
 241                                 --      2 server status request
 242                                 --      3-15 reserved
 243         o.qr = o.qr or 0;               --  1b  0 query, 1 response
 244
 245         o.rcode = o.rcode or 0; --  4b  0 no error
 246                                 --      1 format error
 247                                 --      2 server failure
 248                                 --      3 name error
 249                                 --      4 not implemented
 250                                 --      5 refused
 251                                 --      6-15 reserved
 252         o.z = o.z  or 0;                --  3b  0 resvered
 253         o.ra = o.ra or 0;               --  1b  1 recursion available
 254
 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
 259
 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
 269         );
 270
 271         return header, o.id;
 272 end
 273
 274
 275 local function encodeName(name)    -- - - - - - - - - - - - - - - - encodeName
 276         local t = {};
 277         for part in string.gmatch(name, '[^.]+') do
 278                 append(t, string.char(string.len(part)));
 279                 append(t, part);
 280         end
 281         append(t, string.char(0));
 282         return table.concat(t);
 283 end
 284
 285
 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;
 291 end
 292
 293
 294 function resolver:byte(len)    -- - - - - - - - - - - - - - - - - - - - - byte
 295         len = len or 1;
 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));
 300         end
 301         self.offset = offset + len;
 302         return string.byte(self.packet, offset, last);
 303 end
 304
 305
 306 function resolver:word()    -- - - - - - - - - - - - - - - - - - - - - -  word
 307         local b1, b2 = self:byte(2);
 308         return 0x100*b1 + b2;
 309 end
 310
 311
 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;
 316 end
 317
 318
 319 function resolver:sub(len)    -- - - - - - - - - - - - - - - - - - - - - - sub
 320         len = len or 1;
 321         local s = string.sub(self.packet, self.offset, self.offset + len - 1);
 322         self.offset = self.offset + len;
 323         return s;
 324 end
 325
 326
 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
 331
 332         local h = { id = id };
 333
 334         local b1, b2 = self:byte(2);
 335
 336         h.rd      = b1 %2;
 337         h.tc      = b1 /2%2;
 338         h.aa      = b1 /4%2;
 339         h.opcode  = b1 /8%16;
 340         h.qr      = b1 /128;
 341
 342         h.rcode   = b2 %16;
 343         h.z       = b2 /16%8;
 344         h.ra      = b2 /128;
 345
 346         h.qdcount = self:word();
 347         h.ancount = self:word();
 348         h.nscount = self:word();
 349         h.arcount = self:word();
 350
 351         for k,v in pairs(h) do h[k] = v-v%1; end
 352
 353         return h;
 354 end
 355
 356
 357 function resolver:name()    -- - - - - - - - - - - - - - - - - - - - - -  name
 358         local remember, pointers = nil, 0;
 359         local len = self:byte();
 360         local n = {};
 361         if len == 0 then return "." end -- Root label
 362         while len > 0 do
 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)..'.');
 371                 end
 372                 len = self:byte();
 373         end
 374         self.offset = remember or self.offset;
 375         return table.concat(n);
 376 end
 377
 378
 379 function resolver:question()    -- - - - - - - - - - - - - - - - - -  question
 380         local q = {};
 381         q.name  = self:name();
 382         q.type  = dns.type[self:word()];
 383         q.class = dns.class[self:word()];
 384         return q;
 385 end
 386
 387
 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);
 391 end
 392
 393 function resolver:AAAA(rr)
 394         local addr = {};
 395         for i = 1, rr.rdlength, 2 do
 396                 local b1, b2 = self:byte(2);
 397                 table.insert(addr, ("%02x%02x"):format(b1, b2));
 398         end
 399         addr = table.concat(addr, ":"):gsub("%f[%x]0+(%x)","%1");
 400         local zeros = {};
 401         for item in addr:gmatch(":[0:]+:") do
 402                 table.insert(zeros, item)
 403         end
 404         if #zeros == 0 then
 405                 rr.aaaa = addr;
 406                 return
 407         elseif #zeros > 1 then
 408                 table.sort(zeros, function(a, b) return #a > #b end);
 409         end
 410         rr.aaaa = addr:gsub(zeros[1], "::", 1):gsub("^0::", "::"):gsub("::0$", "::");
 411 end
 412
 413 function resolver:CNAME(rr)    -- - - - - - - - - - - - - - - - - - - -  CNAME
 414         rr.cname = self:name();
 415 end
 416
 417
 418 function resolver:MX(rr)    -- - - - - - - - - - - - - - - - - - - - - - -  MX
 419         rr.pref = self:word();
 420         rr.mx   = self:name();
 421 end
 422
 423
 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));
 428 end
 429
 430
 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();
 441         end
 442 end
 443
 444
 445 local function LOC_tostring_degrees(f, pos, neg)    -- - - - - - - - - - - - -
 446         f = f - 0x80000000;
 447         if f < 0 then pos = neg; f = -f; end
 448         local deg, min, msec;
 449         msec = f%60000;
 450         f    = (f-msec)/60000;
 451         min  = f%60;
 452         deg = (f-min)/60;
 453         return string.format('%3d %2d %2.3f %s', deg, min, msec/1000, pos);
 454 end
 455
 456
 457 function resolver.LOC_tostring(rr)    -- - - - - - - - - - - - -  LOC_tostring
 458         local t = {};
 459
 460         --[[
 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]));
 463         end
 464         --]]
 465
 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,
 471                 rr.loc.size / 100,
 472                 rr.loc.horiz_pre / 100,
 473                 rr.loc.vert_pre / 100
 474         ));
 475
 476         return table.concat(t);
 477 end
 478
 479
 480 function resolver:NS(rr)    -- - - - - - - - - - - - - - - - - - - - - - -  NS
 481         rr.ns = self:name();
 482 end
 483
 484
 485 function resolver:SOA(rr)    -- - - - - - - - - - - - - - - - - - - - - -  SOA
 486 end
 487
 488
 489 function resolver:SRV(rr)    -- - - - - - - - - - - - - - - - - - - - - -  SRV
 490           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();
 495 end
 496
 497 function resolver:PTR(rr)
 498         rr.ptr = self:name();
 499 end
 500
 501 function resolver:TXT(rr)    -- - - - - - - - - - - - - - - - - - - - - -  TXT
 502         rr.txt = self:sub (self:byte());
 503 end
 504
 505
 506 function resolver:rr()    -- - - - - - - - - - - - - - - - - - - - - - - -  rr
 507         local 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();
 514
 515         if rr.ttl <= 0 then
 516                 rr.tod = self.time + 30;
 517         else
 518                 rr.tod = self.time + rr.ttl;
 519         end
 520
 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);
 526         return rr;
 527 end
 528
 529
 530 function resolver:rrs (count)    -- - - - - - - - - - - - - - - - - - - - - rrs
 531         local rrs = {};
 532         for i = 1,count do append(rrs, self:rr()); end
 533         return rrs;
 534 end
 535
 536
 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 };
 542
 543         response.question = {};
 544         local offset = self.offset;
 545         for i = 1,response.header.qdcount do
 546                 append(response.question, self:question());
 547         end
 548         response.question.raw = string.sub(self.packet, offset, self.offset - 1);
 549
 550         if not force then
 551                 if not self.active[response.header.id] or not self.active[response.header.id][response.question.raw] then
 552                         return nil;
 553                 end
 554         end
 555
 556         response.answer     = self:rrs(response.header.ancount);
 557         response.authority  = self:rrs(response.header.nscount);
 558         response.additional = self:rrs(response.header.arcount);
 559
 560         return response;
 561 end
 562
 563
 564 -- socket layer -------------------------------------------------- socket layer
 565
 566
 567 resolver.delays = { 1, 3 };
 568
 569
 570 function resolver:addnameserver(address)    -- - - - - - - - - - addnameserver
 571         self.server = self.server or {};
 572         append(self.server, address);
 573 end
 574
 575
 576 function resolver:setnameserver(address)    -- - - - - - - - - - setnameserver
 577         self.server = {};
 578         self:addnameserver(address);
 579 end
 580
 581
 582 function resolver:adddefaultnameservers()    -- - - - -  adddefaultnameservers
 583         if is_windows then
 584                 if windows and windows.get_nameservers then
 585                         for _, server in ipairs(windows.get_nameservers()) do
 586                                 self:addnameserver(server);
 587                         end
 588                 end
 589                 if not self.server or #self.server == 0 then
 590                         -- TODO log warning about no nameservers, adding opendns servers as fallback
 591                         self:addnameserver("208.67.222.222");
 592                         self:addnameserver("208.67.220.220");
 593                 end
 594         else -- posix
 595                 local resolv_conf = io.open("/etc/resolv.conf");
 596                 if resolv_conf then
 597                         for line in resolv_conf:lines() do
 598                                 line = line:gsub("#.*$", "")
 599                                         :match('^%s*nameserver%s+(.*)%s*$');
 600                                 if line then
 601                                         line:gsub("%f[%d.](%d+%.%d+%.%d+%.%d+)%f[^%d.]", function (address)
 602                                                 self:addnameserver(address)
 603                                         end);
 604                                 end
 605                         end
 606                 end
 607                 if not self.server or #self.server == 0 then
 608                         -- TODO log warning about no nameservers, adding localhost as the default nameserver
 609                         self:addnameserver("127.0.0.1");
 610                 end
 611         end
 612 end
 613
 614
 615 function resolver:getsocket(servernum)    -- - - - - - - - - - - - - getsocket
 616         self.socket = self.socket or {};
 617         self.socketset = self.socketset or {};
 618
 619         local sock = self.socket[servernum];
 620         if sock then return sock; end
 621
 622         local err;
 623         sock, err = socket.udp();
 624         if not sock then
 625                 return nil, err;
 626         end
 627         if self.socket_wrapper then sock = self.socket_wrapper(sock, self); end
 628         sock:settimeout(0);
 629         -- todo: attempt to use a random port, fallback to 0
 630         sock:setsockname('*', 0);
 631         sock:setpeername(self.server[servernum], 53);
 632         self.socket[servernum] = sock;
 633         self.socketset[sock] = servernum;
 634         return sock;
 635 end
 636
 637 function resolver:voidsocket(sock)
 638         if self.socket[sock] then
 639                 self.socketset[self.socket[sock]] = nil;
 640                 self.socket[sock] = nil;
 641         elseif self.socketset[sock] then
 642                 self.socket[self.socketset[sock]] = nil;
 643                 self.socketset[sock] = nil;
 644         end
 645 end
 646
 647 function resolver:socket_wrapper_set(func)  -- - - - - - - socket_wrapper_set
 648         self.socket_wrapper = func;
 649 end
 650
 651
 652 function resolver:closeall ()    -- - - - - - - - - - - - - - - - - -  closeall
 653         for i,sock in ipairs(self.socket) do
 654                 self.socket[i] = nil;
 655                 self.socketset[sock] = nil;
 656                 sock:close();
 657         end
 658 end
 659
 660
 661 function resolver:remember(rr, type)    -- - - - - - - - - - - - - -  remember
 662         --print ('remember', type, rr.class, rr.type, rr.name)
 663         local qname, qtype, qclass = standardize(rr.name, rr.type, rr.class);
 664
 665         if type ~= '*' then
 666                 type = qtype;
 667                 local all = get(self.cache, qclass, '*', qname);
 668                 --print('remember all', all);
 669                 if all then append(all, rr); end
 670         end
 671
 672         self.cache = self.cache or setmetatable({}, cache_metatable);
 673         local rrs = get(self.cache, qclass, type, qname) or
 674                 set(self.cache, qclass, type, qname, setmetatable({}, rrs_metatable));
 675         append(rrs, rr);
 676
 677         if type == 'MX' then self.unsorted[rrs] = true; end
 678 end
 679
 680
 681 local function comp_mx(a, b)    -- - - - - - - - - - - - - - - - - - - comp_mx
 682         return (a.pref == b.pref) and (a.mx < b.mx) or (a.pref < b.pref);
 683 end
 684
 685
 686 function resolver:peek (qname, qtype, qclass)    -- - - - - - - - - - - -  peek
 687         qname, qtype, qclass = standardize(qname, qtype, qclass);
 688         local rrs = get(self.cache, qclass, qtype, qname);
 689         if not rrs then return nil; end
 690         if prune(rrs, socket.gettime()) and qtype == '*' or not next(rrs) then
 691                 set(self.cache, qclass, qtype, qname, nil);
 692                 return nil;
 693         end
 694         if self.unsorted[rrs] then table.sort (rrs, comp_mx); end
 695         return rrs;
 696 end
 697
 698
 699 function resolver:purge(soft)    -- - - - - - - - - - - - - - - - - - -  purge
 700         if soft == 'soft' then
 701                 self.time = socket.gettime();
 702                 for class,types in pairs(self.cache or {}) do
 703                         for type,names in pairs(types) do
 704                                 for name,rrs in pairs(names) do
 705                                         prune(rrs, self.time, 'soft')
 706                                 end
 707                         end
 708                 end
 709         else self.cache = setmetatable({}, cache_metatable); end
 710 end
 711
 712
 713 function resolver:query(qname, qtype, qclass)    -- - - - - - - - - - -- query
 714         qname, qtype, qclass = standardize(qname, qtype, qclass)
 715
 716         if not self.server then self:adddefaultnameservers(); end
 717
 718         local question = encodeQuestion(qname, qtype, qclass);
 719         local peek = self:peek (qname, qtype, qclass);
 720         if peek then return peek; end
 721
 722         local header, id = encodeHeader();
 723         --print ('query  id', id, qclass, qtype, qname)
 724         local o = {
 725                 packet = header..question,
 726                 server = self.best_server,
 727                 delay  = 1,
 728                 retry  = socket.gettime() + self.delays[1]
 729         };
 730
 731         -- remember the query
 732         self.active[id] = self.active[id] or {};
 733         self.active[id][question] = o;
 734
 735         -- remember which coroutine wants the answer
 736         local co = coroutine.running();
 737         if co then
 738                 set(self.wanted, qclass, qtype, qname, co, true);
 739                 --set(self.yielded, co, qclass, qtype, qname, true);
 740         end
 741
 742         local conn, err = self:getsocket(o.server)
 743         if not conn then
 744                 return nil, err;
 745         end
 746         conn:send (o.packet)
 747
 748         if timer and self.timeout then
 749                 local num_servers = #self.server;
 750                 local i = 1;
 751                 timer.add_task(self.timeout, function ()
 752                         if get(self.wanted, qclass, qtype, qname, co) then
 753                                 if i < num_servers then
 754                                         i = i + 1;
 755                                         self:servfail(conn);
 756                                         o.server = self.best_server;
 757                                         conn, err = self:getsocket(o.server);
 758                                         if conn then
 759                                                 conn:send(o.packet);
 760                                                 return self.timeout;
 761                                         end
 762                                 end
 763                                 -- Tried everything, failed
 764                                 self:cancel(qclass, qtype, qname, co, true);
 765                         end
 766                 end)
 767         end
 768         return true;
 769 end
 770
 771 function resolver:servfail(sock)
 772         -- Resend all queries for this server
 773
 774         local num = self.socketset[sock]
 775
 776         -- Socket is dead now
 777         self:voidsocket(sock);
 778
 779         -- Find all requests to the down server, and retry on the next server
 780         self.time = socket.gettime();
 781         for id,queries in pairs(self.active) do
 782                 for question,o in pairs(queries) do
 783                         if o.server == num then -- This request was to the broken server
 784                                 o.server = o.server + 1 -- Use next server
 785                                 if o.server > #self.server then
 786                                         o.server = 1;
 787                                 end
 788
 789                                 o.retries = (o.retries or 0) + 1;
 790                                 if o.retries >= #self.server then
 791                                         --print('timeout');
 792                                         queries[question] = nil;
 793                                 else
 794                                         local _a = self:getsocket(o.server);
 795                                         if _a then _a:send(o.packet); end
 796                                 end
 797                         end
 798                 end
 799         end
 800
 801         if num == self.best_server then
 802                 self.best_server = self.best_server + 1;
 803                 if self.best_server > #self.server then
 804                         -- Exhausted all servers, try first again
 805                         self.best_server = 1;
 806                 end
 807         end
 808 end
 809
 810 function resolver:settimeout(seconds)
 811         self.timeout = seconds;
 812 end
 813
 814 function resolver:receive(rset)    -- - - - - - - - - - - - - - - - -  receive
 815         --print('receive');  print(self.socket);
 816         self.time = socket.gettime();
 817         rset = rset or self.socket;
 818
 819         local response;
 820         for i,sock in pairs(rset) do
 821
 822                 if self.socketset[sock] then
 823                         local packet = sock:receive();
 824                         if packet then
 825                                 response = self:decode(packet);
 826                                 if response and self.active[response.header.id]
 827                                         and self.active[response.header.id][response.question.raw] then
 828                                         --print('received response');
 829                                         --self.print(response);
 830
 831                                         for j,rr in pairs(response.answer) do
 832                                                 if rr.name:sub(-#response.question[1].name, -1) == response.question[1].name then
 833                                                         self:remember(rr, response.question[1].type)
 834                                                 end
 835                                         end
 836
 837                                         -- retire the query
 838                                         local queries = self.active[response.header.id];
 839                                         queries[response.question.raw] = nil;
 840
 841                                         if not next(queries) then self.active[response.header.id] = nil; end
 842                                         if not next(self.active) then self:closeall(); end
 843
 844                                         -- was the query on the wanted list?
 845                                         local q = response.question[1];
 846                                         local cos = get(self.wanted, q.class, q.type, q.name);
 847                                         if cos then
 848                                                 for co in pairs(cos) do
 849                                                         set(self.yielded, co, q.class, q.type, q.name, nil);
 850                                                         if coroutine.status(co) == "suspended" then coroutine.resume(co); end
 851                                                 end
 852                                                 set(self.wanted, q.class, q.type, q.name, nil);
 853                                         end
 854                                 end
 855                         end
 856                 end
 857         end
 858
 859         return response;
 860 end
 861
 862
 863 function resolver:feed(sock, packet, force)
 864         --print('receive'); print(self.socket);
 865         self.time = socket.gettime();
 866
 867         local response = self:decode(packet, force);
 868         if response and self.active[response.header.id]
 869                 and self.active[response.header.id][response.question.raw] then
 870                 --print('received response');
 871                 --self.print(response);
 872
 873                 for j,rr in pairs(response.answer) do
 874                         self:remember(rr, response.question[1].type);
 875                 end
 876
 877                 -- retire the query
 878                 local queries = self.active[response.header.id];
 879                 queries[response.question.raw] = nil;
 880                 if not next(queries) then self.active[response.header.id] = nil; end
 881                 if not next(self.active) then self:closeall(); end
 882
 883                 -- was the query on the wanted list?
 884                 local q = response.question[1];
 885                 if q then
 886                         local cos = get(self.wanted, q.class, q.type, q.name);
 887                         if cos then
 888                                 for co in pairs(cos) do
 889                                         set(self.yielded, co, q.class, q.type, q.name, nil);
 890                                         if coroutine.status(co) == "suspended" then coroutine.resume(co); end
 891                                 end
 892                                 set(self.wanted, q.class, q.type, q.name, nil);
 893                         end
 894                 end
 895         end
 896
 897         return response;
 898 end
 899
 900 function resolver:cancel(qclass, qtype, qname, co, call_handler)
 901         local cos = get(self.wanted, qclass, qtype, qname);
 902         if cos then
 903                 if call_handler then
 904                         coroutine.resume(co);
 905                 end
 906                 cos[co] = nil;
 907         end
 908 end
 909
 910 function resolver:pulse()    -- - - - - - - - - - - - - - - - - - - - -  pulse
 911         --print(':pulse');
 912         while self:receive() do end
 913         if not next(self.active) then return nil; end
 914
 915         self.time = socket.gettime();
 916         for id,queries in pairs(self.active) do
 917                 for question,o in pairs(queries) do
 918                         if self.time >= o.retry then
 919
 920                                 o.server = o.server + 1;
 921                                 if o.server > #self.server then
 922                                         o.server = 1;
 923                                         o.delay = o.delay + 1;
 924                                 end
 925
 926                                 if o.delay > #self.delays then
 927                                         --print('timeout');
 928                                         queries[question] = nil;
 929                                         if not next(queries) then self.active[id] = nil; end
 930                                         if not next(self.active) then return nil; end
 931                                 else
 932                                         --print('retry', o.server, o.delay);
 933                                         local _a = self.socket[o.server];
 934                                         if _a then _a:send(o.packet); end
 935                                         o.retry = self.time + self.delays[o.delay];
 936                                 end
 937                         end
 938                 end
 939         end
 940
 941         if next(self.active) then return true; end
 942         return nil;
 943 end
 944
 945
 946 function resolver:lookup(qname, qtype, qclass)    -- - - - - - - - - -  lookup
 947         self:query (qname, qtype, qclass)
 948         while self:pulse() do
 949                 local recvt = {}
 950                 for i, s in ipairs(self.socket) do
 951                         recvt[i] = s
 952                 end
 953                 socket.select(recvt, nil, 4)
 954         end
 955         --print(self.cache);
 956         return self:peek(qname, qtype, qclass);
 957 end
 958
 959 function resolver:lookupex(handler, qname, qtype, qclass)    -- - - - - - - - - -  lookup
 960         return self:peek(qname, qtype, qclass) or self:query(qname, qtype, qclass);
 961 end
 962
 963 function resolver:tohostname(ip)
 964         return dns.lookup(ip:gsub("(%d+)%.(%d+)%.(%d+)%.(%d+)", "%4.%3.%2.%1.in-addr.arpa."), "PTR");
 965 end
 966
 967 --print ---------------------------------------------------------------- print
 968
 969
 970 local hints = {    -- - - - - - - - - - - - - - - - - - - - - - - - - - - hints
 971         qr = { [0]='query', 'response' },
 972         opcode = { [0]='query', 'inverse query', 'server status request' },
 973         aa = { [0]='non-authoritative', 'authoritative' },
 974         tc = { [0]='complete', 'truncated' },
 975         rd = { [0]='recursion not desired', 'recursion desired' },
 976         ra = { [0]='recursion not available', 'recursion available' },
 977         z  = { [0]='(reserved)' },
 978         rcode = { [0]='no error', 'format error', 'server failure', 'name error', 'not implemented' },
 979
 980         type = dns.type,
 981         class = dns.class
 982 };
 983
 984
 985 local function hint(p, s)    -- - - - - - - - - - - - - - - - - - - - - - hint
 986         return (hints[s] and hints[s][p[s]]) or '';
 987 end
 988
 989
 990 function resolver.print(response)    -- - - - - - - - - - - - - resolver.print
 991         for s,s in pairs { 'id', 'qr', 'opcode', 'aa', 'tc', 'rd', 'ra', 'z',
 992                                                 'rcode', 'qdcount', 'ancount', 'nscount', 'arcount' } do
 993                 print( string.format('%-30s', 'header.'..s), response.header[s], hint(response.header, s) );
 994         end
 995
 996         for i,question in ipairs(response.question) do
 997                 print(string.format ('question[%i].name         ', i), question.name);
 998                 print(string.format ('question[%i].type         ', i), question.type);
 999                 print(string.format ('question[%i].class        ', i), question.class);
1000         end
1001
1002         local common = { name=1, type=1, class=1, ttl=1, rdlength=1, rdata=1 };
1003         local tmp;
1004         for s,s in pairs({'answer', 'authority', 'additional'}) do
1005                 for i,rr in pairs(response[s]) do
1006                         for j,t in pairs({ 'name', 'type', 'class', 'ttl', 'rdlength' }) do
1007                                 tmp = string.format('%s[%i].%s', s, i, t);
1008                                 print(string.format('%-30s', tmp), rr[t], hint(rr, t));
1009                         end
1010                         for j,t in pairs(rr) do
1011                                 if not common[j] then
1012                                         tmp = string.format('%s[%i].%s', s, i, j);
1013                                         print(string.format('%-30s  %s', tostring(tmp), tostring(t)));
1014                                 end
1015                         end
1016                 end
1017         end
1018 end
1019
1020
1021 -- module api ------------------------------------------------------ module api
1022
1023
1024 function dns.resolver ()    -- - - - - - - - - - - - - - - - - - - - - resolver
1025         -- this function seems to be redundant with resolver.new ()
1026
1027         local r = { active = {}, cache = {}, unsorted = {}, wanted = {}, yielded = {}, best_server = 1 };
1028         setmetatable (r, resolver);
1029         setmetatable (r.cache, cache_metatable);
1030         setmetatable (r.unsorted, { __mode = 'kv' });
1031         return r;
1032 end
1033
1034 local _resolver = dns.resolver();
1035 dns._resolver = _resolver;
1036
1037 function dns.lookup(...)    -- - - - - - - - - - - - - - - - - - - - -  lookup
1038         return _resolver:lookup(...);
1039 end
1040
1041 function dns.tohostname(...)
1042         return _resolver:tohostname(...);
1043 end
1044
1045 function dns.purge(...)    -- - - - - - - - - - - - - - - - - - - - - -  purge
1046         return _resolver:purge(...);
1047 end
1048
1049 function dns.peek(...)    -- - - - - - - - - - - - - - - - - - - - - - -  peek
1050         return _resolver:peek(...);
1051 end
1052
1053 function dns.query(...)    -- - - - - - - - - - - - - - - - - - - - - -  query
1054         return _resolver:query(...);
1055 end
1056
1057 function dns.feed(...)    -- - - - - - - - - - - - - - - - - - - - - - -  feed
1058         return _resolver:feed(...);
1059 end
1060
1061 function dns.cancel(...)  -- - - - - - - - - - - - - - - - - - - - - -  cancel
1062         return _resolver:cancel(...);
1063 end
1064
1065 function dns.settimeout(...)
1066         return _resolver:settimeout(...);
1067 end
1068
1069 function dns.socket_wrapper_set(...)    -- - - - - - - - -  socket_wrapper_set
1070         return _resolver:socket_wrapper_set(...);
1071 end
1072
1073 return dns;