src/coremods/core_dns.cpp

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