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