src/coremods/core_dns.cpp

   1 /*
   2  * InspIRCd -- Internet Relay Chat Daemon
   3  *
   4  *   Copyright (C) 2013 Adam <Adam@anope.org>
   5  *   Copyright (C) 2003-2013 Anope Team <team@anope.org>
   6  *
   7  * This file is part of InspIRCd.  InspIRCd is free software: you can
   8  * redistribute it and/or modify it under the terms of the GNU General Public
   9  * License as published by the Free Software Foundation, version 2.
  10  *
  11  * This program is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  13  * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
  14  * details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include "inspircd.h"
  21 #include "modules/dns.h"
  22 #include <iostream>
  23 #include <fstream>
  24
  25 #ifdef _WIN32
  26 #include <Iphlpapi.h>
  27 #pragma comment(lib, "Iphlpapi.lib")
  28 #endif
  29
  30 using namespace DNS;
  31
  32 /** A full packet sent or recieved to/from the nameserver
  33  */
  34 class Packet : public Query
  35 {
  36         void PackName(unsigned char* output, unsigned short output_size, unsigned short& pos, const std::string& name)
  37         {
  38                 if (pos + name.length() + 2 > output_size)
  39                         throw Exception("Unable to pack name");
  40
  41                 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Packing name " + name);
  42
  43                 irc::sepstream sep(name, '.');
  44                 std::string token;
  45
  46                 while (sep.GetToken(token))
  47                 {
  48                         output[pos++] = token.length();
  49                         memcpy(&output[pos], token.data(), token.length());
  50                         pos += token.length();
  51                 }
  52
  53                 output[pos++] = 0;
  54         }
  55
  56         std::string UnpackName(const unsigned char* input, unsigned short input_size, unsigned short& pos)
  57         {
  58                 std::string name;
  59                 unsigned short pos_ptr = pos, lowest_ptr = input_size;
  60                 bool compressed = false;
  61
  62                 if (pos_ptr >= input_size)
  63                         throw Exception("Unable to unpack name - no input");
  64
  65                 while (input[pos_ptr] > 0)
  66                 {
  67                         unsigned short offset = input[pos_ptr];
  68
  69                         if (offset & POINTER)
  70                         {
  71                                 if ((offset & POINTER) != POINTER)
  72                                         throw Exception("Unable to unpack name - bogus compression header");
  73                                 if (pos_ptr + 1 >= input_size)
  74                                         throw Exception("Unable to unpack name - bogus compression header");
  75
  76                                 /* Place pos at the second byte of the first (farthest) compression pointer */
  77                                 if (compressed == false)
  78                                 {
  79                                         ++pos;
  80                                         compressed = true;
  81                                 }
  82
  83                                 pos_ptr = (offset & LABEL) << 8 | input[pos_ptr + 1];
  84
  85                                 /* Pointers can only go back */
  86                                 if (pos_ptr >= lowest_ptr)
  87                                         throw Exception("Unable to unpack name - bogus compression pointer");
  88                                 lowest_ptr = pos_ptr;
  89                         }
  90                         else
  91                         {
  92                                 if (pos_ptr + offset + 1 >= input_size)
  93                                         throw Exception("Unable to unpack name - offset too large");
  94                                 if (!name.empty())
  95                                         name += ".";
  96                                 for (unsigned i = 1; i <= offset; ++i)
  97                                         name += input[pos_ptr + i];
  98
  99                                 pos_ptr += offset + 1;
 100                                 if (compressed == false)
 101                                         /* Move up pos */
 102                                         pos = pos_ptr;
 103                         }
 104                 }
 105
 106                 /* +1 pos either to one byte after the compression pointer or one byte after the ending \0 */
 107                 ++pos;
 108
 109                 if (name.empty())
 110                         throw Exception("Unable to unpack name - no name");
 111
 112                 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Unpack name " + name);
 113
 114                 return name;
 115         }
 116
 117         Question UnpackQuestion(const unsigned char* input, unsigned short input_size, unsigned short& pos)
 118         {
 119                 Question question;
 120
 121                 question.name = this->UnpackName(input, input_size, pos);
 122
 123                 if (pos + 4 > input_size)
 124                         throw Exception("Unable to unpack question");
 125
 126                 question.type = static_cast<QueryType>(input[pos] << 8 | input[pos + 1]);
 127                 pos += 2;
 128
 129                 question.qclass = input[pos] << 8 | input[pos + 1];
 130                 pos += 2;
 131
 132                 return question;
 133         }
 134
 135         ResourceRecord UnpackResourceRecord(const unsigned char* input, unsigned short input_size, unsigned short& pos)
 136         {
 137                 ResourceRecord record = static_cast<ResourceRecord>(this->UnpackQuestion(input, input_size, pos));
 138
 139                 if (pos + 6 > input_size)
 140                         throw Exception("Unable to unpack resource record");
 141
 142                 record.ttl = (input[pos] << 24) | (input[pos + 1] << 16) | (input[pos + 2] << 8) | input[pos + 3];
 143                 pos += 4;
 144
 145                 //record.rdlength = input[pos] << 8 | input[pos + 1];
 146                 pos += 2;
 147
 148                 switch (record.type)
 149                 {
 150                         case QUERY_A:
 151                         {
 152                                 if (pos + 4 > input_size)
 153                                         throw Exception("Unable to unpack resource record");
 154
 155                                 irc::sockets::sockaddrs addrs;
 156                                 memset(&addrs, 0, sizeof(addrs));
 157
 158                                 addrs.in4.sin_family = AF_INET;
 159                                 addrs.in4.sin_addr.s_addr = input[pos] | (input[pos + 1] << 8) | (input[pos + 2] << 16)  | (input[pos + 3] << 24);
 160                                 pos += 4;
 161
 162                                 record.rdata = addrs.addr();
 163                                 break;
 164                         }
 165                         case QUERY_AAAA:
 166                         {
 167                                 if (pos + 16 > input_size)
 168                                         throw Exception("Unable to unpack resource record");
 169
 170                                 irc::sockets::sockaddrs addrs;
 171                                 memset(&addrs, 0, sizeof(addrs));
 172
 173                                 addrs.in6.sin6_family = AF_INET6;
 174                                 for (int j = 0; j < 16; ++j)
 175                                         addrs.in6.sin6_addr.s6_addr[j] = input[pos + j];
 176                                 pos += 16;
 177
 178                                 record.rdata = addrs.addr();
 179
 180                                 break;
 181                         }
 182                         case QUERY_CNAME:
 183                         case QUERY_PTR:
 184                         {
 185                                 record.rdata = this->UnpackName(input, input_size, pos);
 186                                 break;
 187                         }
 188                         default:
 189                                 break;
 190                 }
 191
 192                 if (!record.name.empty() && !record.rdata.empty())
 193                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, record.name + " -> " + record.rdata);
 194
 195                 return record;
 196         }
 197
 198  public:
 199         static const int POINTER = 0xC0;
 200         static const int LABEL = 0x3F;
 201         static const int HEADER_LENGTH = 12;
 202
 203         /* ID for this packet */
 204         unsigned short id;
 205         /* Flags on the packet */
 206         unsigned short flags;
 207
 208         Packet() : id(0), flags(0)
 209         {
 210         }
 211
 212         void Fill(const unsigned char* input, const unsigned short len)
 213         {
 214                 if (len < HEADER_LENGTH)
 215                         throw Exception("Unable to fill packet");
 216
 217                 unsigned short packet_pos = 0;
 218
 219                 this->id = (input[packet_pos] << 8) | input[packet_pos + 1];
 220                 packet_pos += 2;
 221
 222                 if (this->id >= MAX_REQUEST_ID)
 223                         throw Exception("Query ID too large?");
 224
 225                 this->flags = (input[packet_pos] << 8) | input[packet_pos + 1];
 226                 packet_pos += 2;
 227
 228                 unsigned short qdcount = (input[packet_pos] << 8) | input[packet_pos + 1];
 229                 packet_pos += 2;
 230
 231                 unsigned short ancount = (input[packet_pos] << 8) | input[packet_pos + 1];
 232                 packet_pos += 2;
 233
 234                 unsigned short nscount = (input[packet_pos] << 8) | input[packet_pos + 1];
 235                 packet_pos += 2;
 236
 237                 unsigned short arcount = (input[packet_pos] << 8) | input[packet_pos + 1];
 238                 packet_pos += 2;
 239
 240                 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "qdcount: " + ConvToStr(qdcount) + " ancount: " + ConvToStr(ancount) + " nscount: " + ConvToStr(nscount) + " arcount: " + ConvToStr(arcount));
 241
 242                 for (unsigned i = 0; i < qdcount; ++i)
 243                         this->questions.push_back(this->UnpackQuestion(input, len, packet_pos));
 244
 245                 for (unsigned i = 0; i < ancount; ++i)
 246                         this->answers.push_back(this->UnpackResourceRecord(input, len, packet_pos));
 247         }
 248
 249         unsigned short Pack(unsigned char* output, unsigned short output_size)
 250         {
 251                 if (output_size < HEADER_LENGTH)
 252                         throw Exception("Unable to pack packet");
 253
 254                 unsigned short pos = 0;
 255
 256                 output[pos++] = this->id >> 8;
 257                 output[pos++] = this->id & 0xFF;
 258                 output[pos++] = this->flags >> 8;
 259                 output[pos++] = this->flags & 0xFF;
 260                 output[pos++] = this->questions.size() >> 8;
 261                 output[pos++] = this->questions.size() & 0xFF;
 262                 output[pos++] = this->answers.size() >> 8;
 263                 output[pos++] = this->answers.size() & 0xFF;
 264                 output[pos++] = 0;
 265                 output[pos++] = 0;
 266                 output[pos++] = 0;
 267                 output[pos++] = 0;
 268
 269                 for (unsigned i = 0; i < this->questions.size(); ++i)
 270                 {
 271                         Question& q = this->questions[i];
 272
 273                         if (q.type == QUERY_PTR)
 274                         {
 275                                 irc::sockets::sockaddrs ip;
 276                                 irc::sockets::aptosa(q.name, 0, ip);
 277
 278                                 if (q.name.find(':') != std::string::npos)
 279                                 {
 280                                         static const char* const hex = "0123456789abcdef";
 281                                         char reverse_ip[128];
 282                                         unsigned reverse_ip_count = 0;
 283                                         for (int j = 15; j >= 0; --j)
 284                                         {
 285                                                 reverse_ip[reverse_ip_count++] = hex[ip.in6.sin6_addr.s6_addr[j] & 0xF];
 286                                                 reverse_ip[reverse_ip_count++] = '.';
 287                                                 reverse_ip[reverse_ip_count++] = hex[ip.in6.sin6_addr.s6_addr[j] >> 4];
 288                                                 reverse_ip[reverse_ip_count++] = '.';
 289                                         }
 290                                         reverse_ip[reverse_ip_count++] = 0;
 291
 292                                         q.name = reverse_ip;
 293                                         q.name += "ip6.arpa";
 294                                 }
 295                                 else
 296                                 {
 297                                         unsigned long forward = ip.in4.sin_addr.s_addr;
 298                                         ip.in4.sin_addr.s_addr = forward << 24 | (forward & 0xFF00) << 8 | (forward & 0xFF0000) >> 8 | forward >> 24;
 299
 300                                         q.name = ip.addr() + ".in-addr.arpa";
 301                                 }
 302                         }
 303
 304                         this->PackName(output, output_size, pos, q.name);
 305
 306                         if (pos + 4 >= output_size)
 307                                 throw Exception("Unable to pack packet");
 308
 309                         short s = htons(q.type);
 310                         memcpy(&output[pos], &s, 2);
 311                         pos += 2;
 312
 313                         s = htons(q.qclass);
 314                         memcpy(&output[pos], &s, 2);
 315                         pos += 2;
 316                 }
 317
 318                 for (unsigned int i = 0; i < answers.size(); i++)
 319                 {
 320                         ResourceRecord& rr = answers[i];
 321
 322                         this->PackName(output, output_size, pos, rr.name);
 323
 324                         if (pos + 8 >= output_size)
 325                                 throw Exception("Unable to pack packet");
 326
 327                         short s = htons(rr.type);
 328                         memcpy(&output[pos], &s, 2);
 329                         pos += 2;
 330
 331                         s = htons(rr.qclass);
 332                         memcpy(&output[pos], &s, 2);
 333                         pos += 2;
 334
 335                         long l = htonl(rr.ttl);
 336                         memcpy(&output[pos], &l, 4);
 337                         pos += 4;
 338
 339                         switch (rr.type)
 340                         {
 341                                 case QUERY_A:
 342                                 {
 343                                         if (pos + 6 > output_size)
 344                                                 throw Exception("Unable to pack packet");
 345
 346                                         irc::sockets::sockaddrs a;
 347                                         irc::sockets::aptosa(rr.rdata, 0, a);
 348
 349                                         s = htons(4);
 350                                         memcpy(&output[pos], &s, 2);
 351                                         pos += 2;
 352
 353                                         memcpy(&output[pos], &a.in4.sin_addr, 4);
 354                                         pos += 4;
 355                                         break;
 356                                 }
 357                                 case QUERY_AAAA:
 358                                 {
 359                                         if (pos + 18 > output_size)
 360                                                 throw Exception("Unable to pack packet");
 361
 362                                         irc::sockets::sockaddrs a;
 363                                         irc::sockets::aptosa(rr.rdata, 0, a);
 364
 365                                         s = htons(16);
 366                                         memcpy(&output[pos], &s, 2);
 367                                         pos += 2;
 368
 369                                         memcpy(&output[pos], &a.in6.sin6_addr, 16);
 370                                         pos += 16;
 371                                         break;
 372                                 }
 373                                 case QUERY_CNAME:
 374                                 case QUERY_PTR:
 375                                 {
 376                                         if (pos + 2 >= output_size)
 377                                                 throw Exception("Unable to pack packet");
 378
 379                                         unsigned short packet_pos_save = pos;
 380                                         pos += 2;
 381
 382                                         this->PackName(output, output_size, pos, rr.rdata);
 383
 384                                         s = htons(pos - packet_pos_save - 2);
 385                                         memcpy(&output[packet_pos_save], &s, 2);
 386                                         break;
 387                                 }
 388                                 default:
 389                                         break;
 390                         }
 391                 }
 392
 393                 return pos;
 394         }
 395 };
 396
 397 class MyManager : public Manager, public Timer, public EventHandler
 398 {
 399         typedef TR1NS::unordered_map<Question, Query, Question::hash> cache_map;
 400         cache_map cache;
 401
 402         irc::sockets::sockaddrs myserver;
 403
 404         static bool IsExpired(const Query& record, time_t now = ServerInstance->Time())
 405         {
 406                 const ResourceRecord& req = record.answers[0];
 407                 return (req.created + static_cast<time_t>(req.ttl) < now);
 408         }
 409
 410         /** Check the DNS cache to see if request can be handled by a cached result
 411          * @return true if a cached result was found.
 412          */
 413         bool CheckCache(DNS::Request* req, const DNS::Question& question)
 414         {
 415                 ServerInstance->Logs->Log(MODNAME, LOG_SPARSE, "cache: Checking cache for " + question.name);
 416
 417                 cache_map::iterator it = this->cache.find(question);
 418                 if (it == this->cache.end())
 419                         return false;
 420
 421                 Query& record = it->second;
 422                 if (IsExpired(record))
 423                 {
 424                         this->cache.erase(it);
 425                         return false;
 426                 }
 427
 428                 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "cache: Using cached result for " + question.name);
 429                 record.cached = true;
 430                 req->OnLookupComplete(&record);
 431                 return true;
 432         }
 433
 434         /** Add a record to the dns cache
 435          * @param r The record
 436          */
 437         void AddCache(Query& r)
 438         {
 439                 const ResourceRecord& rr = r.answers[0];
 440                 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "cache: added cache for " + rr.name + " -> " + rr.rdata + " ttl: " + ConvToStr(rr.ttl));
 441                 this->cache[r.questions[0]] = r;
 442         }
 443
 444  public:
 445         DNS::Request* requests[MAX_REQUEST_ID];
 446
 447         MyManager(Module* c) : Manager(c), Timer(3600, true)
 448         {
 449                 for (int i = 0; i < MAX_REQUEST_ID; ++i)
 450                         requests[i] = NULL;
 451                 ServerInstance->Timers.AddTimer(this);
 452         }
 453
 454         ~MyManager()
 455         {
 456                 for (int i = 0; i < MAX_REQUEST_ID; ++i)
 457                 {
 458                         DNS::Request* request = requests[i];
 459                         if (!request)
 460                                 continue;
 461
 462                         Query rr(*request);
 463                         rr.error = ERROR_UNKNOWN;
 464                         request->OnError(&rr);
 465
 466                         delete request;
 467                 }
 468         }
 469
 470         void Process(DNS::Request* req)
 471         {
 472                 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Processing request to lookup " + req->name + " of type " + ConvToStr(req->type) + " to " + this->myserver.addr());
 473
 474                 /* Create an id */
 475                 unsigned int tries = 0;
 476                 do
 477                 {
 478                         req->id = ServerInstance->GenRandomInt(DNS::MAX_REQUEST_ID);
 479
 480                         if (++tries == DNS::MAX_REQUEST_ID*5)
 481                         {
 482                                 // If we couldn't find an empty slot this many times, do a sequential scan as a last
 483                                 // resort. If an empty slot is found that way, go on, otherwise throw an exception
 484                                 req->id = 0;
 485                                 for (int i = 1; i < DNS::MAX_REQUEST_ID; i++)
 486                                 {
 487                                         if (!this->requests[i])
 488                                         {
 489                                                 req->id = i;
 490                                                 break;
 491                                         }
 492                                 }
 493
 494                                 if (req->id == 0)
 495                                         throw Exception("DNS: All ids are in use");
 496
 497                                 break;
 498                         }
 499                 }
 500                 while (!req->id || this->requests[req->id]);
 501
 502                 this->requests[req->id] = req;
 503
 504                 Packet p;
 505                 p.flags = QUERYFLAGS_RD;
 506                 p.id = req->id;
 507                 p.questions.push_back(*req);
 508
 509                 unsigned char buffer[524];
 510                 unsigned short len = p.Pack(buffer, sizeof(buffer));
 511
 512                 /* Note that calling Pack() above can actually change the contents of p.questions[0].name, if the query is a PTR,
 513                  * to contain the value that would be in the DNS cache, which is why this is here.
 514                  */
 515                 if (req->use_cache && this->CheckCache(req, p.questions[0]))
 516                 {
 517                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Using cached result");
 518                         delete req;
 519                         return;
 520                 }
 521
 522                 if (SocketEngine::SendTo(this, buffer, len, 0, &this->myserver.sa, this->myserver.sa_size()) != len)
 523                         throw Exception("DNS: Unable to send query");
 524         }
 525
 526         void RemoveRequest(DNS::Request* req)
 527         {
 528                 this->requests[req->id] = NULL;
 529         }
 530
 531         std::string GetErrorStr(Error e)
 532         {
 533                 switch (e)
 534                 {
 535                         case ERROR_UNLOADED:
 536                                 return "Module is unloading";
 537                         case ERROR_TIMEDOUT:
 538                                 return "Request timed out";
 539                         case ERROR_NOT_AN_ANSWER:
 540                         case ERROR_NONSTANDARD_QUERY:
 541                         case ERROR_FORMAT_ERROR:
 542                                 return "Malformed answer";
 543                         case ERROR_SERVER_FAILURE:
 544                         case ERROR_NOT_IMPLEMENTED:
 545                         case ERROR_REFUSED:
 546                         case ERROR_INVALIDTYPE:
 547                                 return "Nameserver failure";
 548                         case ERROR_DOMAIN_NOT_FOUND:
 549                         case ERROR_NO_RECORDS:
 550                                 return "Domain not found";
 551                         case ERROR_NONE:
 552                         case ERROR_UNKNOWN:
 553                         default:
 554                                 return "Unknown error";
 555                 }
 556         }
 557
 558         void OnEventHandlerError(int errcode) CXX11_OVERRIDE
 559         {
 560                 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "UDP socket got an error event");
 561         }
 562
 563         void OnEventHandlerRead() CXX11_OVERRIDE
 564         {
 565                 unsigned char buffer[524];
 566                 irc::sockets::sockaddrs from;
 567                 socklen_t x = sizeof(from);
 568
 569                 int length = SocketEngine::RecvFrom(this, buffer, sizeof(buffer), 0, &from.sa, &x);
 570
 571                 if (length < Packet::HEADER_LENGTH)
 572                         return;
 573
 574                 Packet recv_packet;
 575
 576                 try
 577                 {
 578                         recv_packet.Fill(buffer, length);
 579                 }
 580                 catch (Exception& ex)
 581                 {
 582                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, ex.GetReason());
 583                         return;
 584                 }
 585
 586                 if (myserver != from)
 587                 {
 588                         std::string server1 = from.str();
 589                         std::string server2 = myserver.str();
 590                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Got a result from the wrong server! Bad NAT or DNS forging attempt? '%s' != '%s'",
 591                                 server1.c_str(), server2.c_str());
 592                         return;
 593                 }
 594
 595                 DNS::Request* request = this->requests[recv_packet.id];
 596                 if (request == NULL)
 597                 {
 598                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Received an answer for something we didn't request");
 599                         return;
 600                 }
 601
 602                 if (recv_packet.flags & QUERYFLAGS_OPCODE)
 603                 {
 604                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Received a nonstandard query");
 605                         ServerInstance->stats.DnsBad++;
 606                         recv_packet.error = ERROR_NONSTANDARD_QUERY;
 607                         request->OnError(&recv_packet);
 608                 }
 609                 else if (recv_packet.flags & QUERYFLAGS_RCODE)
 610                 {
 611                         Error error = ERROR_UNKNOWN;
 612
 613                         switch (recv_packet.flags & QUERYFLAGS_RCODE)
 614                         {
 615                                 case 1:
 616                                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "format error");
 617                                         error = ERROR_FORMAT_ERROR;
 618                                         break;
 619                                 case 2:
 620                                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "server error");
 621                                         error = ERROR_SERVER_FAILURE;
 622                                         break;
 623                                 case 3:
 624                                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "domain not found");
 625                                         error = ERROR_DOMAIN_NOT_FOUND;
 626                                         break;
 627                                 case 4:
 628                                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "not implemented");
 629                                         error = ERROR_NOT_IMPLEMENTED;
 630                                         break;
 631                                 case 5:
 632                                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "refused");
 633                                         error = ERROR_REFUSED;
 634                                         break;
 635                                 default:
 636                                         break;
 637                         }
 638
 639                         ServerInstance->stats.DnsBad++;
 640                         recv_packet.error = error;
 641                         request->OnError(&recv_packet);
 642                 }
 643                 else if (recv_packet.questions.empty() || recv_packet.answers.empty())
 644                 {
 645                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "No resource records returned");
 646                         ServerInstance->stats.DnsBad++;
 647                         recv_packet.error = ERROR_NO_RECORDS;
 648                         request->OnError(&recv_packet);
 649                 }
 650                 else
 651                 {
 652                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Lookup complete for " + request->name);
 653                         ServerInstance->stats.DnsGood++;
 654                         request->OnLookupComplete(&recv_packet);
 655                         this->AddCache(recv_packet);
 656                 }
 657
 658                 ServerInstance->stats.Dns++;
 659
 660                 /* Request's destructor removes it from the request map */
 661                 delete request;
 662         }
 663
 664         bool Tick(time_t now)
 665         {
 666                 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "cache: purging DNS cache");
 667
 668                 for (cache_map::iterator it = this->cache.begin(); it != this->cache.end(); )
 669                 {
 670                         const Query& query = it->second;
 671                         if (IsExpired(query, now))
 672                                 this->cache.erase(it++);
 673                         else
 674                                 ++it;
 675                 }
 676                 return true;
 677         }
 678
 679         void Rehash(const std::string& dnsserver)
 680         {
 681                 if (this->GetFd() > -1)
 682                 {
 683                         SocketEngine::Shutdown(this, 2);
 684                         SocketEngine::Close(this);
 685
 686                         /* Remove expired entries from the cache */
 687                         this->Tick(ServerInstance->Time());
 688                 }
 689
 690                 irc::sockets::aptosa(dnsserver, DNS::PORT, myserver);
 691
 692                 /* Initialize mastersocket */
 693                 int s = socket(myserver.sa.sa_family, SOCK_DGRAM, 0);
 694                 this->SetFd(s);
 695
 696                 /* Have we got a socket? */
 697                 if (this->GetFd() != -1)
 698                 {
 699                         SocketEngine::SetReuse(s);
 700                         SocketEngine::NonBlocking(s);
 701
 702                         irc::sockets::sockaddrs bindto;
 703                         memset(&bindto, 0, sizeof(bindto));
 704                         bindto.sa.sa_family = myserver.sa.sa_family;
 705
 706                         if (SocketEngine::Bind(this->GetFd(), bindto) < 0)
 707                         {
 708                                 /* Failed to bind */
 709                                 ServerInstance->Logs->Log(MODNAME, LOG_SPARSE, "Error binding dns socket - hostnames will NOT resolve");
 710                                 SocketEngine::Close(this->GetFd());
 711                                 this->SetFd(-1);
 712                         }
 713                         else if (!SocketEngine::AddFd(this, FD_WANT_POLL_READ | FD_WANT_NO_WRITE))
 714                         {
 715                                 ServerInstance->Logs->Log(MODNAME, LOG_SPARSE, "Internal error starting DNS - hostnames will NOT resolve.");
 716                                 SocketEngine::Close(this->GetFd());
 717                                 this->SetFd(-1);
 718                         }
 719                 }
 720                 else
 721                 {
 722                         ServerInstance->Logs->Log(MODNAME, LOG_SPARSE, "Error creating DNS socket - hostnames will NOT resolve");
 723                 }
 724         }
 725 };
 726
 727 class ModuleDNS : public Module
 728 {
 729         MyManager manager;
 730         std::string DNSServer;
 731
 732         void FindDNSServer()
 733         {
 734 #ifdef _WIN32
 735                 // attempt to look up their nameserver from the system
 736                 ServerInstance->Logs->Log("CONFIG", LOG_DEFAULT, "WARNING: <dns:server> not defined, attempting to find a working server in the system settings...");
 737
 738                 PFIXED_INFO pFixedInfo;
 739                 DWORD dwBufferSize = sizeof(FIXED_INFO);
 740                 pFixedInfo = (PFIXED_INFO) HeapAlloc(GetProcessHeap(), 0, sizeof(FIXED_INFO));
 741
 742                 if (pFixedInfo)
 743                 {
 744                         if (GetNetworkParams(pFixedInfo, &dwBufferSize) == ERROR_BUFFER_OVERFLOW)
 745                         {
 746                                 HeapFree(GetProcessHeap(), 0, pFixedInfo);
 747                                 pFixedInfo = (PFIXED_INFO) HeapAlloc(GetProcessHeap(), 0, dwBufferSize);
 748                         }
 749
 750                         if (pFixedInfo)
 751                         {
 752                                 if (GetNetworkParams(pFixedInfo, &dwBufferSize) == NO_ERROR)
 753                                         DNSServer = pFixedInfo->DnsServerList.IpAddress.String;
 754
 755                                 HeapFree(GetProcessHeap(), 0, pFixedInfo);
 756                         }
 757
 758                         if (!DNSServer.empty())
 759                         {
 760                                 ServerInstance->Logs->Log("CONFIG", LOG_DEFAULT, "<dns:server> set to '%s' as first active resolver in the system settings.", DNSServer.c_str());
 761                                 return;
 762                         }
 763                 }
 764
 765                 ServerInstance->Logs->Log("CONFIG", LOG_DEFAULT, "No viable nameserver found! Defaulting to nameserver '127.0.0.1'!");
 766 #else
 767                 // attempt to look up their nameserver from /etc/resolv.conf
 768                 ServerInstance->Logs->Log("CONFIG", LOG_DEFAULT, "WARNING: <dns:server> not defined, attempting to find working server in /etc/resolv.conf...");
 769
 770                 std::ifstream resolv("/etc/resolv.conf");
 771
 772                 while (resolv >> DNSServer)
 773                 {
 774                         if (DNSServer == "nameserver")
 775                         {
 776                                 resolv >> DNSServer;
 777                                 if (DNSServer.find_first_not_of("0123456789.") == std::string::npos)
 778                                 {
 779                                         ServerInstance->Logs->Log("CONFIG", LOG_DEFAULT, "<dns:server> set to '%s' as first resolver in /etc/resolv.conf.",DNSServer.c_str());
 780                                         return;
 781                                 }
 782                         }
 783                 }
 784
 785                 ServerInstance->Logs->Log("CONFIG", LOG_DEFAULT, "/etc/resolv.conf contains no viable nameserver entries! Defaulting to nameserver '127.0.0.1'!");
 786 #endif
 787                 DNSServer = "127.0.0.1";
 788         }
 789
 790  public:
 791         ModuleDNS() : manager(this)
 792         {
 793         }
 794
 795         void ReadConfig(ConfigStatus& status) CXX11_OVERRIDE
 796         {
 797                 std::string oldserver = DNSServer;
 798                 DNSServer = ServerInstance->Config->ConfValue("dns")->getString("server");
 799                 if (DNSServer.empty())
 800                         FindDNSServer();
 801
 802                 if (oldserver != DNSServer)
 803                         this->manager.Rehash(DNSServer);
 804         }
 805
 806         void OnUnloadModule(Module* mod)
 807         {
 808                 for (int i = 0; i < MAX_REQUEST_ID; ++i)
 809                 {
 810                         DNS::Request* req = this->manager.requests[i];
 811                         if (!req)
 812                                 continue;
 813
 814                         if (req->creator == mod)
 815                         {
 816                                 Query rr(*req);
 817                                 rr.error = ERROR_UNLOADED;
 818                                 req->OnError(&rr);
 819
 820                                 delete req;
 821                         }
 822                 }
 823         }
 824
 825         Version GetVersion()
 826         {
 827                 return Version("DNS support", VF_CORE|VF_VENDOR);
 828         }
 829 };
 830
 831 MODULE_INIT(ModuleDNS)
 832