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 q;
 120
 121                 q.name = this->UnpackName(input, input_size, pos);
 122
 123                 if (pos + 4 > input_size)
 124                         throw Exception("Unable to unpack question");
 125
 126                 q.type = static_cast<QueryType>(input[pos] << 8 | input[pos + 1]);
 127                 pos += 2;
 128
 129                 // Skip over query class code
 130                 pos += 2;
 131
 132                 return q;
 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         RequestId 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                 this->flags = (input[packet_pos] << 8) | input[packet_pos + 1];
 223                 packet_pos += 2;
 224
 225                 unsigned short qdcount = (input[packet_pos] << 8) | input[packet_pos + 1];
 226                 packet_pos += 2;
 227
 228                 unsigned short ancount = (input[packet_pos] << 8) | input[packet_pos + 1];
 229                 packet_pos += 2;
 230
 231                 unsigned short nscount = (input[packet_pos] << 8) | input[packet_pos + 1];
 232                 packet_pos += 2;
 233
 234                 unsigned short arcount = (input[packet_pos] << 8) | input[packet_pos + 1];
 235                 packet_pos += 2;
 236
 237                 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "qdcount: " + ConvToStr(qdcount) + " ancount: " + ConvToStr(ancount) + " nscount: " + ConvToStr(nscount) + " arcount: " + ConvToStr(arcount));
 238
 239                 if (qdcount != 1)
 240                         throw Exception("Question count != 1 in incoming packet");
 241
 242                 this->question = this->UnpackQuestion(input, len, packet_pos);
 243
 244                 for (unsigned i = 0; i < ancount; ++i)
 245                         this->answers.push_back(this->UnpackResourceRecord(input, len, packet_pos));
 246         }
 247
 248         unsigned short Pack(unsigned char* output, unsigned short output_size)
 249         {
 250                 if (output_size < HEADER_LENGTH)
 251                         throw Exception("Unable to pack packet");
 252
 253                 unsigned short pos = 0;
 254
 255                 output[pos++] = this->id >> 8;
 256                 output[pos++] = this->id & 0xFF;
 257                 output[pos++] = this->flags >> 8;
 258                 output[pos++] = this->flags & 0xFF;
 259                 output[pos++] = 0; // Question count, high byte
 260                 output[pos++] = 1; // Question count, low byte
 261                 output[pos++] = 0; // Answer count, high byte
 262                 output[pos++] = 0; // Answer count, low byte
 263                 output[pos++] = 0;
 264                 output[pos++] = 0;
 265                 output[pos++] = 0;
 266                 output[pos++] = 0;
 267
 268                 {
 269                         Question& q = this->question;
 270
 271                         if (q.type == QUERY_PTR)
 272                         {
 273                                 irc::sockets::sockaddrs ip;
 274                                 irc::sockets::aptosa(q.name, 0, ip);
 275
 276                                 if (q.name.find(':') != std::string::npos)
 277                                 {
 278                                         static const char* const hex = "0123456789abcdef";
 279                                         char reverse_ip[128];
 280                                         unsigned reverse_ip_count = 0;
 281                                         for (int j = 15; j >= 0; --j)
 282                                         {
 283                                                 reverse_ip[reverse_ip_count++] = hex[ip.in6.sin6_addr.s6_addr[j] & 0xF];
 284                                                 reverse_ip[reverse_ip_count++] = '.';
 285                                                 reverse_ip[reverse_ip_count++] = hex[ip.in6.sin6_addr.s6_addr[j] >> 4];
 286                                                 reverse_ip[reverse_ip_count++] = '.';
 287                                         }
 288                                         reverse_ip[reverse_ip_count++] = 0;
 289
 290                                         q.name = reverse_ip;
 291                                         q.name += "ip6.arpa";
 292                                 }
 293                                 else
 294                                 {
 295                                         unsigned long forward = ip.in4.sin_addr.s_addr;
 296                                         ip.in4.sin_addr.s_addr = forward << 24 | (forward & 0xFF00) << 8 | (forward & 0xFF0000) >> 8 | forward >> 24;
 297
 298                                         q.name = ip.addr() + ".in-addr.arpa";
 299                                 }
 300                         }
 301
 302                         this->PackName(output, output_size, pos, q.name);
 303
 304                         if (pos + 4 >= output_size)
 305                                 throw Exception("Unable to pack packet");
 306
 307                         short s = htons(q.type);
 308                         memcpy(&output[pos], &s, 2);
 309                         pos += 2;
 310
 311                         // Query class, always IN
 312                         output[pos++] = 0;
 313                         output[pos++] = 1;
 314                 }
 315
 316                 return pos;
 317         }
 318 };
 319
 320 class MyManager : public Manager, public Timer, public EventHandler
 321 {
 322         typedef TR1NS::unordered_map<Question, Query, Question::hash> cache_map;
 323         cache_map cache;
 324
 325         irc::sockets::sockaddrs myserver;
 326
 327         static bool IsExpired(const Query& record, time_t now = ServerInstance->Time())
 328         {
 329                 const ResourceRecord& req = record.answers[0];
 330                 return (req.created + static_cast<time_t>(req.ttl) < now);
 331         }
 332
 333         /** Check the DNS cache to see if request can be handled by a cached result
 334          * @return true if a cached result was found.
 335          */
 336         bool CheckCache(DNS::Request* req, const DNS::Question& question)
 337         {
 338                 ServerInstance->Logs->Log(MODNAME, LOG_SPARSE, "cache: Checking cache for " + question.name);
 339
 340                 cache_map::iterator it = this->cache.find(question);
 341                 if (it == this->cache.end())
 342                         return false;
 343
 344                 Query& record = it->second;
 345                 if (IsExpired(record))
 346                 {
 347                         this->cache.erase(it);
 348                         return false;
 349                 }
 350
 351                 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "cache: Using cached result for " + question.name);
 352                 record.cached = true;
 353                 req->OnLookupComplete(&record);
 354                 return true;
 355         }
 356
 357         /** Add a record to the dns cache
 358          * @param r The record
 359          */
 360         void AddCache(Query& r)
 361         {
 362                 const ResourceRecord& rr = r.answers[0];
 363                 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "cache: added cache for " + rr.name + " -> " + rr.rdata + " ttl: " + ConvToStr(rr.ttl));
 364                 this->cache[r.question] = r;
 365         }
 366
 367  public:
 368         DNS::Request* requests[MAX_REQUEST_ID+1];
 369
 370         MyManager(Module* c) : Manager(c), Timer(3600, true)
 371         {
 372                 for (unsigned int i = 0; i <= MAX_REQUEST_ID; ++i)
 373                         requests[i] = NULL;
 374                 ServerInstance->Timers.AddTimer(this);
 375         }
 376
 377         ~MyManager()
 378         {
 379                 for (unsigned int i = 0; i <= MAX_REQUEST_ID; ++i)
 380                 {
 381                         DNS::Request* request = requests[i];
 382                         if (!request)
 383                                 continue;
 384
 385                         Query rr(*request);
 386                         rr.error = ERROR_UNKNOWN;
 387                         request->OnError(&rr);
 388
 389                         delete request;
 390                 }
 391         }
 392
 393         void Process(DNS::Request* req)
 394         {
 395                 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Processing request to lookup " + req->name + " of type " + ConvToStr(req->type) + " to " + this->myserver.addr());
 396
 397                 /* Create an id */
 398                 unsigned int tries = 0;
 399                 int id;
 400                 do
 401                 {
 402                         id = ServerInstance->GenRandomInt(DNS::MAX_REQUEST_ID+1);
 403
 404                         if (++tries == DNS::MAX_REQUEST_ID*5)
 405                         {
 406                                 // If we couldn't find an empty slot this many times, do a sequential scan as a last
 407                                 // resort. If an empty slot is found that way, go on, otherwise throw an exception
 408                                 id = -1;
 409                                 for (unsigned int i = 0; i <= DNS::MAX_REQUEST_ID; i++)
 410                                 {
 411                                         if (!this->requests[i])
 412                                         {
 413                                                 id = i;
 414                                                 break;
 415                                         }
 416                                 }
 417
 418                                 if (id == -1)
 419                                         throw Exception("DNS: All ids are in use");
 420
 421                                 break;
 422                         }
 423                 }
 424                 while (this->requests[id]);
 425
 426                 req->id = id;
 427                 this->requests[req->id] = req;
 428
 429                 Packet p;
 430                 p.flags = QUERYFLAGS_RD;
 431                 p.id = req->id;
 432                 p.question = *req;
 433
 434                 unsigned char buffer[524];
 435                 unsigned short len = p.Pack(buffer, sizeof(buffer));
 436
 437                 /* Note that calling Pack() above can actually change the contents of p.question.name, if the query is a PTR,
 438                  * to contain the value that would be in the DNS cache, which is why this is here.
 439                  */
 440                 if (req->use_cache && this->CheckCache(req, p.question))
 441                 {
 442                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Using cached result");
 443                         delete req;
 444                         return;
 445                 }
 446
 447                 // Update name in the original request so question checking works for PTR queries
 448                 req->name = p.question.name;
 449
 450                 if (SocketEngine::SendTo(this, buffer, len, 0, &this->myserver.sa, this->myserver.sa_size()) != len)
 451                         throw Exception("DNS: Unable to send query");
 452         }
 453
 454         void RemoveRequest(DNS::Request* req)
 455         {
 456                 this->requests[req->id] = NULL;
 457         }
 458
 459         std::string GetErrorStr(Error e)
 460         {
 461                 switch (e)
 462                 {
 463                         case ERROR_UNLOADED:
 464                                 return "Module is unloading";
 465                         case ERROR_TIMEDOUT:
 466                                 return "Request timed out";
 467                         case ERROR_NOT_AN_ANSWER:
 468                         case ERROR_NONSTANDARD_QUERY:
 469                         case ERROR_FORMAT_ERROR:
 470                                 return "Malformed answer";
 471                         case ERROR_SERVER_FAILURE:
 472                         case ERROR_NOT_IMPLEMENTED:
 473                         case ERROR_REFUSED:
 474                         case ERROR_INVALIDTYPE:
 475                                 return "Nameserver failure";
 476                         case ERROR_DOMAIN_NOT_FOUND:
 477                         case ERROR_NO_RECORDS:
 478                                 return "Domain not found";
 479                         case ERROR_NONE:
 480                         case ERROR_UNKNOWN:
 481                         default:
 482                                 return "Unknown error";
 483                 }
 484         }
 485
 486         void OnEventHandlerError(int errcode) CXX11_OVERRIDE
 487         {
 488                 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "UDP socket got an error event");
 489         }
 490
 491         void OnEventHandlerRead() CXX11_OVERRIDE
 492         {
 493                 unsigned char buffer[524];
 494                 irc::sockets::sockaddrs from;
 495                 socklen_t x = sizeof(from);
 496
 497                 int length = SocketEngine::RecvFrom(this, buffer, sizeof(buffer), 0, &from.sa, &x);
 498
 499                 if (length < Packet::HEADER_LENGTH)
 500                         return;
 501
 502                 if (myserver != from)
 503                 {
 504                         std::string server1 = from.str();
 505                         std::string server2 = myserver.str();
 506                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Got a result from the wrong server! Bad NAT or DNS forging attempt? '%s' != '%s'",
 507                                 server1.c_str(), server2.c_str());
 508                         return;
 509                 }
 510
 511                 Packet recv_packet;
 512
 513                 try
 514                 {
 515                         recv_packet.Fill(buffer, length);
 516                 }
 517                 catch (Exception& ex)
 518                 {
 519                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, ex.GetReason());
 520                         return;
 521                 }
 522
 523                 DNS::Request* request = this->requests[recv_packet.id];
 524                 if (request == NULL)
 525                 {
 526                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Received an answer for something we didn't request");
 527                         return;
 528                 }
 529
 530                 if (recv_packet.flags & QUERYFLAGS_OPCODE)
 531                 {
 532                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Received a nonstandard query");
 533                         ServerInstance->stats.DnsBad++;
 534                         recv_packet.error = ERROR_NONSTANDARD_QUERY;
 535                         request->OnError(&recv_packet);
 536                 }
 537                 else if (recv_packet.flags & QUERYFLAGS_RCODE)
 538                 {
 539                         Error error = ERROR_UNKNOWN;
 540
 541                         switch (recv_packet.flags & QUERYFLAGS_RCODE)
 542                         {
 543                                 case 1:
 544                                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "format error");
 545                                         error = ERROR_FORMAT_ERROR;
 546                                         break;
 547                                 case 2:
 548                                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "server error");
 549                                         error = ERROR_SERVER_FAILURE;
 550                                         break;
 551                                 case 3:
 552                                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "domain not found");
 553                                         error = ERROR_DOMAIN_NOT_FOUND;
 554                                         break;
 555                                 case 4:
 556                                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "not implemented");
 557                                         error = ERROR_NOT_IMPLEMENTED;
 558                                         break;
 559                                 case 5:
 560                                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "refused");
 561                                         error = ERROR_REFUSED;
 562                                         break;
 563                                 default:
 564                                         break;
 565                         }
 566
 567                         ServerInstance->stats.DnsBad++;
 568                         recv_packet.error = error;
 569                         request->OnError(&recv_packet);
 570                 }
 571                 else if (recv_packet.answers.empty())
 572                 {
 573                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "No resource records returned");
 574                         ServerInstance->stats.DnsBad++;
 575                         recv_packet.error = ERROR_NO_RECORDS;
 576                         request->OnError(&recv_packet);
 577                 }
 578                 else
 579                 {
 580                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Lookup complete for " + request->name);
 581                         ServerInstance->stats.DnsGood++;
 582                         request->OnLookupComplete(&recv_packet);
 583                         this->AddCache(recv_packet);
 584                 }
 585
 586                 ServerInstance->stats.Dns++;
 587
 588                 /* Request's destructor removes it from the request map */
 589                 delete request;
 590         }
 591
 592         bool Tick(time_t now)
 593         {
 594                 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "cache: purging DNS cache");
 595
 596                 for (cache_map::iterator it = this->cache.begin(); it != this->cache.end(); )
 597                 {
 598                         const Query& query = it->second;
 599                         if (IsExpired(query, now))
 600                                 this->cache.erase(it++);
 601                         else
 602                                 ++it;
 603                 }
 604                 return true;
 605         }
 606
 607         void Rehash(const std::string& dnsserver)
 608         {
 609                 if (this->GetFd() > -1)
 610                 {
 611                         SocketEngine::Shutdown(this, 2);
 612                         SocketEngine::Close(this);
 613
 614                         /* Remove expired entries from the cache */
 615                         this->Tick(ServerInstance->Time());
 616                 }
 617
 618                 irc::sockets::aptosa(dnsserver, DNS::PORT, myserver);
 619
 620                 /* Initialize mastersocket */
 621                 int s = socket(myserver.sa.sa_family, SOCK_DGRAM, 0);
 622                 this->SetFd(s);
 623
 624                 /* Have we got a socket? */
 625                 if (this->GetFd() != -1)
 626                 {
 627                         SocketEngine::SetReuse(s);
 628                         SocketEngine::NonBlocking(s);
 629
 630                         irc::sockets::sockaddrs bindto;
 631                         memset(&bindto, 0, sizeof(bindto));
 632                         bindto.sa.sa_family = myserver.sa.sa_family;
 633
 634                         if (SocketEngine::Bind(this->GetFd(), bindto) < 0)
 635                         {
 636                                 /* Failed to bind */
 637                                 ServerInstance->Logs->Log(MODNAME, LOG_SPARSE, "Error binding dns socket - hostnames will NOT resolve");
 638                                 SocketEngine::Close(this->GetFd());
 639                                 this->SetFd(-1);
 640                         }
 641                         else if (!SocketEngine::AddFd(this, FD_WANT_POLL_READ | FD_WANT_NO_WRITE))
 642                         {
 643                                 ServerInstance->Logs->Log(MODNAME, LOG_SPARSE, "Internal error starting DNS - hostnames will NOT resolve.");
 644                                 SocketEngine::Close(this->GetFd());
 645                                 this->SetFd(-1);
 646                         }
 647                 }
 648                 else
 649                 {
 650                         ServerInstance->Logs->Log(MODNAME, LOG_SPARSE, "Error creating DNS socket - hostnames will NOT resolve");
 651                 }
 652         }
 653 };
 654
 655 class ModuleDNS : public Module
 656 {
 657         MyManager manager;
 658         std::string DNSServer;
 659
 660         void FindDNSServer()
 661         {
 662 #ifdef _WIN32
 663                 // attempt to look up their nameserver from the system
 664                 ServerInstance->Logs->Log("CONFIG", LOG_DEFAULT, "WARNING: <dns:server> not defined, attempting to find a working server in the system settings...");
 665
 666                 PFIXED_INFO pFixedInfo;
 667                 DWORD dwBufferSize = sizeof(FIXED_INFO);
 668                 pFixedInfo = (PFIXED_INFO) HeapAlloc(GetProcessHeap(), 0, sizeof(FIXED_INFO));
 669
 670                 if (pFixedInfo)
 671                 {
 672                         if (GetNetworkParams(pFixedInfo, &dwBufferSize) == ERROR_BUFFER_OVERFLOW)
 673                         {
 674                                 HeapFree(GetProcessHeap(), 0, pFixedInfo);
 675                                 pFixedInfo = (PFIXED_INFO) HeapAlloc(GetProcessHeap(), 0, dwBufferSize);
 676                         }
 677
 678                         if (pFixedInfo)
 679                         {
 680                                 if (GetNetworkParams(pFixedInfo, &dwBufferSize) == NO_ERROR)
 681                                         DNSServer = pFixedInfo->DnsServerList.IpAddress.String;
 682
 683                                 HeapFree(GetProcessHeap(), 0, pFixedInfo);
 684                         }
 685
 686                         if (!DNSServer.empty())
 687                         {
 688                                 ServerInstance->Logs->Log("CONFIG", LOG_DEFAULT, "<dns:server> set to '%s' as first active resolver in the system settings.", DNSServer.c_str());
 689                                 return;
 690                         }
 691                 }
 692
 693                 ServerInstance->Logs->Log("CONFIG", LOG_DEFAULT, "No viable nameserver found! Defaulting to nameserver '127.0.0.1'!");
 694 #else
 695                 // attempt to look up their nameserver from /etc/resolv.conf
 696                 ServerInstance->Logs->Log("CONFIG", LOG_DEFAULT, "WARNING: <dns:server> not defined, attempting to find working server in /etc/resolv.conf...");
 697
 698                 std::ifstream resolv("/etc/resolv.conf");
 699
 700                 while (resolv >> DNSServer)
 701                 {
 702                         if (DNSServer == "nameserver")
 703                         {
 704                                 resolv >> DNSServer;
 705                                 if (DNSServer.find_first_not_of("0123456789.") == std::string::npos)
 706                                 {
 707                                         ServerInstance->Logs->Log("CONFIG", LOG_DEFAULT, "<dns:server> set to '%s' as first resolver in /etc/resolv.conf.",DNSServer.c_str());
 708                                         return;
 709                                 }
 710                         }
 711                 }
 712
 713                 ServerInstance->Logs->Log("CONFIG", LOG_DEFAULT, "/etc/resolv.conf contains no viable nameserver entries! Defaulting to nameserver '127.0.0.1'!");
 714 #endif
 715                 DNSServer = "127.0.0.1";
 716         }
 717
 718  public:
 719         ModuleDNS() : manager(this)
 720         {
 721         }
 722
 723         void ReadConfig(ConfigStatus& status) CXX11_OVERRIDE
 724         {
 725                 std::string oldserver = DNSServer;
 726                 DNSServer = ServerInstance->Config->ConfValue("dns")->getString("server");
 727                 if (DNSServer.empty())
 728                         FindDNSServer();
 729
 730                 if (oldserver != DNSServer)
 731                         this->manager.Rehash(DNSServer);
 732         }
 733
 734         void OnUnloadModule(Module* mod)
 735         {
 736                 for (unsigned int i = 0; i <= MAX_REQUEST_ID; ++i)
 737                 {
 738                         DNS::Request* req = this->manager.requests[i];
 739                         if (!req)
 740                                 continue;
 741
 742                         if (req->creator == mod)
 743                         {
 744                                 Query rr(*req);
 745                                 rr.error = ERROR_UNLOADED;
 746                                 req->OnError(&rr);
 747
 748                                 delete req;
 749                         }
 750                 }
 751         }
 752
 753         Version GetVersion()
 754         {
 755                 return Version("DNS support", VF_CORE|VF_VENDOR);
 756         }
 757 };
 758
 759 MODULE_INIT(ModuleDNS)
 760