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