src/coremods/core_dns.cpp

   1 /*
   2  * InspIRCd -- Internet Relay Chat Daemon
   3  *
   4  *   Copyright (C) 2013 Adam <Adam@anope.org>
   5  *   Copyright (C) 2003-2013 Anope Team <team@anope.org>
   6  *
   7  * This file is part of InspIRCd.  InspIRCd is free software: you can
   8  * redistribute it and/or modify it under the terms of the GNU General Public
   9  * License as published by the Free Software Foundation, version 2.
  10  *
  11  * This program is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  13  * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
  14  * details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include "inspircd.h"
  21 #include "modules/dns.h"
  22 #include <iostream>
  23 #include <fstream>
  24
  25 #ifdef _WIN32
  26 #include <Iphlpapi.h>
  27 #pragma comment(lib, "Iphlpapi.lib")
  28 #endif
  29
  30 using namespace DNS;
  31
  32 /** A full packet sent or recieved to/from the nameserver
  33  */
  34 class Packet : public Query
  35 {
  36         void PackName(unsigned char* output, unsigned short output_size, unsigned short& pos, const std::string& name)
  37         {
  38                 if (pos + name.length() + 2 > output_size)
  39                         throw Exception("Unable to pack name");
  40
  41                 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Packing name " + name);
  42
  43                 irc::sepstream sep(name, '.');
  44                 std::string token;
  45
  46                 while (sep.GetToken(token))
  47                 {
  48                         output[pos++] = token.length();
  49                         memcpy(&output[pos], token.data(), token.length());
  50                         pos += token.length();
  51                 }
  52
  53                 output[pos++] = 0;
  54         }
  55
  56         std::string UnpackName(const unsigned char* input, unsigned short input_size, unsigned short& pos)
  57         {
  58                 std::string name;
  59                 unsigned short pos_ptr = pos, lowest_ptr = input_size;
  60                 bool compressed = false;
  61
  62                 if (pos_ptr >= input_size)
  63                         throw Exception("Unable to unpack name - no input");
  64
  65                 while (input[pos_ptr] > 0)
  66                 {
  67                         unsigned short offset = input[pos_ptr];
  68
  69                         if (offset & POINTER)
  70                         {
  71                                 if ((offset & POINTER) != POINTER)
  72                                         throw Exception("Unable to unpack name - bogus compression header");
  73                                 if (pos_ptr + 1 >= input_size)
  74                                         throw Exception("Unable to unpack name - bogus compression header");
  75
  76                                 /* Place pos at the second byte of the first (farthest) compression pointer */
  77                                 if (compressed == false)
  78                                 {
  79                                         ++pos;
  80                                         compressed = true;
  81                                 }
  82
  83                                 pos_ptr = (offset & LABEL) << 8 | input[pos_ptr + 1];
  84
  85                                 /* Pointers can only go back */
  86                                 if (pos_ptr >= lowest_ptr)
  87                                         throw Exception("Unable to unpack name - bogus compression pointer");
  88                                 lowest_ptr = pos_ptr;
  89                         }
  90                         else
  91                         {
  92                                 if (pos_ptr + offset + 1 >= input_size)
  93                                         throw Exception("Unable to unpack name - offset too large");
  94                                 if (!name.empty())
  95                                         name += ".";
  96                                 for (unsigned i = 1; i <= offset; ++i)
  97                                         name += input[pos_ptr + i];
  98
  99                                 pos_ptr += offset + 1;
 100                                 if (compressed == false)
 101                                         /* Move up pos */
 102                                         pos = pos_ptr;
 103                         }
 104                 }
 105
 106                 /* +1 pos either to one byte after the compression pointer or one byte after the ending \0 */
 107                 ++pos;
 108
 109                 if (name.empty())
 110                         throw Exception("Unable to unpack name - no name");
 111
 112                 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Unpack name " + name);
 113
 114                 return name;
 115         }
 116
 117         Question UnpackQuestion(const unsigned char* input, unsigned short input_size, unsigned short& pos)
 118         {
 119                 Question question;
 120
 121                 question.name = this->UnpackName(input, input_size, pos);
 122
 123                 if (pos + 4 > input_size)
 124                         throw Exception("Unable to unpack question");
 125
 126                 question.type = static_cast<QueryType>(input[pos] << 8 | input[pos + 1]);
 127                 pos += 2;
 128
 129                 question.qclass = input[pos] << 8 | input[pos + 1];
 130                 pos += 2;
 131
 132                 return question;
 133         }
 134
 135         ResourceRecord UnpackResourceRecord(const unsigned char* input, unsigned short input_size, unsigned short& pos)
 136         {
 137                 ResourceRecord record = static_cast<ResourceRecord>(this->UnpackQuestion(input, input_size, pos));
 138
 139                 if (pos + 6 > input_size)
 140                         throw Exception("Unable to unpack resource record");
 141
 142                 record.ttl = (input[pos] << 24) | (input[pos + 1] << 16) | (input[pos + 2] << 8) | input[pos + 3];
 143                 pos += 4;
 144
 145                 //record.rdlength = input[pos] << 8 | input[pos + 1];
 146                 pos += 2;
 147
 148                 switch (record.type)
 149                 {
 150                         case QUERY_A:
 151                         {
 152                                 if (pos + 4 > input_size)
 153                                         throw Exception("Unable to unpack resource record");
 154
 155                                 irc::sockets::sockaddrs addrs;
 156                                 memset(&addrs, 0, sizeof(addrs));
 157
 158                                 addrs.in4.sin_family = AF_INET;
 159                                 addrs.in4.sin_addr.s_addr = input[pos] | (input[pos + 1] << 8) | (input[pos + 2] << 16)  | (input[pos + 3] << 24);
 160                                 pos += 4;
 161
 162                                 record.rdata = addrs.addr();
 163                                 break;
 164                         }
 165                         case QUERY_AAAA:
 166                         {
 167                                 if (pos + 16 > input_size)
 168                                         throw Exception("Unable to unpack resource record");
 169
 170                                 irc::sockets::sockaddrs addrs;
 171                                 memset(&addrs, 0, sizeof(addrs));
 172
 173                                 addrs.in6.sin6_family = AF_INET6;
 174                                 for (int j = 0; j < 16; ++j)
 175                                         addrs.in6.sin6_addr.s6_addr[j] = input[pos + j];
 176                                 pos += 16;
 177
 178                                 record.rdata = addrs.addr();
 179
 180                                 break;
 181                         }
 182                         case QUERY_CNAME:
 183                         case QUERY_PTR:
 184                         {
 185                                 record.rdata = this->UnpackName(input, input_size, pos);
 186                                 break;
 187                         }
 188                         default:
 189                                 break;
 190                 }
 191
 192                 if (!record.name.empty() && !record.rdata.empty())
 193                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, record.name + " -> " + record.rdata);
 194
 195                 return record;
 196         }
 197
 198  public:
 199         static const int POINTER = 0xC0;
 200         static const int LABEL = 0x3F;
 201         static const int HEADER_LENGTH = 12;
 202
 203         /* ID for this packet */
 204         unsigned short id;
 205         /* Flags on the packet */
 206         unsigned short flags;
 207
 208         Packet() : id(0), flags(0)
 209         {
 210         }
 211
 212         void Fill(const unsigned char* input, const unsigned short len)
 213         {
 214                 if (len < HEADER_LENGTH)
 215                         throw Exception("Unable to fill packet");
 216
 217                 unsigned short packet_pos = 0;
 218
 219                 this->id = (input[packet_pos] << 8) | input[packet_pos + 1];
 220                 packet_pos += 2;
 221
 222                 if (this->id >= MAX_REQUEST_ID)
 223                         throw Exception("Query ID too large?");
 224
 225                 this->flags = (input[packet_pos] << 8) | input[packet_pos + 1];
 226                 packet_pos += 2;
 227
 228                 unsigned short qdcount = (input[packet_pos] << 8) | input[packet_pos + 1];
 229                 packet_pos += 2;
 230
 231                 unsigned short ancount = (input[packet_pos] << 8) | input[packet_pos + 1];
 232                 packet_pos += 2;
 233
 234                 unsigned short nscount = (input[packet_pos] << 8) | input[packet_pos + 1];
 235                 packet_pos += 2;
 236
 237                 unsigned short arcount = (input[packet_pos] << 8) | input[packet_pos + 1];
 238                 packet_pos += 2;
 239
 240                 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "qdcount: " + ConvToStr(qdcount) + " ancount: " + ConvToStr(ancount) + " nscount: " + ConvToStr(nscount) + " arcount: " + ConvToStr(arcount));
 241
 242                 for (unsigned i = 0; i < qdcount; ++i)
 243                         this->questions.push_back(this->UnpackQuestion(input, len, packet_pos));
 244
 245                 for (unsigned i = 0; i < ancount; ++i)
 246                         this->answers.push_back(this->UnpackResourceRecord(input, len, packet_pos));
 247         }
 248
 249         unsigned short Pack(unsigned char* output, unsigned short output_size)
 250         {
 251                 if (output_size < HEADER_LENGTH)
 252                         throw Exception("Unable to pack packet");
 253
 254                 unsigned short pos = 0;
 255
 256                 output[pos++] = this->id >> 8;
 257                 output[pos++] = this->id & 0xFF;
 258                 output[pos++] = this->flags >> 8;
 259                 output[pos++] = this->flags & 0xFF;
 260                 output[pos++] = this->questions.size() >> 8;
 261                 output[pos++] = this->questions.size() & 0xFF;
 262                 output[pos++] = this->answers.size() >> 8;
 263                 output[pos++] = this->answers.size() & 0xFF;
 264                 output[pos++] = 0;
 265                 output[pos++] = 0;
 266                 output[pos++] = 0;
 267                 output[pos++] = 0;
 268
 269                 for (unsigned i = 0; i < this->questions.size(); ++i)
 270                 {
 271                         Question& q = this->questions[i];
 272
 273                         if (q.type == QUERY_PTR)
 274                         {
 275                                 irc::sockets::sockaddrs ip;
 276                                 irc::sockets::aptosa(q.name, 0, ip);
 277
 278                                 if (q.name.find(':') != std::string::npos)
 279                                 {
 280                                         static const char* const hex = "0123456789abcdef";
 281                                         char reverse_ip[128];
 282                                         unsigned reverse_ip_count = 0;
 283                                         for (int j = 15; j >= 0; --j)
 284                                         {
 285                                                 reverse_ip[reverse_ip_count++] = hex[ip.in6.sin6_addr.s6_addr[j] & 0xF];
 286                                                 reverse_ip[reverse_ip_count++] = '.';
 287                                                 reverse_ip[reverse_ip_count++] = hex[ip.in6.sin6_addr.s6_addr[j] >> 4];
 288                                                 reverse_ip[reverse_ip_count++] = '.';
 289                                         }
 290                                         reverse_ip[reverse_ip_count++] = 0;
 291
 292                                         q.name = reverse_ip;
 293                                         q.name += "ip6.arpa";
 294                                 }
 295                                 else
 296                                 {
 297                                         unsigned long forward = ip.in4.sin_addr.s_addr;
 298                                         ip.in4.sin_addr.s_addr = forward << 24 | (forward & 0xFF00) << 8 | (forward & 0xFF0000) >> 8 | forward >> 24;
 299
 300                                         q.name = ip.addr() + ".in-addr.arpa";
 301                                 }
 302                         }
 303
 304                         this->PackName(output, output_size, pos, q.name);
 305
 306                         if (pos + 4 >= output_size)
 307                                 throw Exception("Unable to pack packet");
 308
 309                         short s = htons(q.type);
 310                         memcpy(&output[pos], &s, 2);
 311                         pos += 2;
 312
 313                         s = htons(q.qclass);
 314                         memcpy(&output[pos], &s, 2);
 315                         pos += 2;
 316                 }
 317
 318                 for (unsigned int i = 0; i < answers.size(); i++)
 319                 {
 320                         ResourceRecord& rr = answers[i];
 321
 322                         this->PackName(output, output_size, pos, rr.name);
 323
 324                         if (pos + 8 >= output_size)
 325                                 throw Exception("Unable to pack packet");
 326
 327                         short s = htons(rr.type);
 328                         memcpy(&output[pos], &s, 2);
 329                         pos += 2;
 330
 331                         s = htons(rr.qclass);
 332                         memcpy(&output[pos], &s, 2);
 333                         pos += 2;
 334
 335                         long l = htonl(rr.ttl);
 336                         memcpy(&output[pos], &l, 4);
 337                         pos += 4;
 338
 339                         switch (rr.type)
 340                         {
 341                                 case QUERY_A:
 342                                 {
 343                                         if (pos + 6 > output_size)
 344                                                 throw Exception("Unable to pack packet");
 345
 346                                         irc::sockets::sockaddrs a;
 347                                         irc::sockets::aptosa(rr.rdata, 0, a);
 348
 349                                         s = htons(4);
 350                                         memcpy(&output[pos], &s, 2);
 351                                         pos += 2;
 352
 353                                         memcpy(&output[pos], &a.in4.sin_addr, 4);
 354                                         pos += 4;
 355                                         break;
 356                                 }
 357                                 case QUERY_AAAA:
 358                                 {
 359                                         if (pos + 18 > output_size)
 360                                                 throw Exception("Unable to pack packet");
 361
 362                                         irc::sockets::sockaddrs a;
 363                                         irc::sockets::aptosa(rr.rdata, 0, a);
 364
 365                                         s = htons(16);
 366                                         memcpy(&output[pos], &s, 2);
 367                                         pos += 2;
 368
 369                                         memcpy(&output[pos], &a.in6.sin6_addr, 16);
 370                                         pos += 16;
 371                                         break;
 372                                 }
 373                                 case QUERY_CNAME:
 374                                 case QUERY_PTR:
 375                                 {
 376                                         if (pos + 2 >= output_size)
 377                                                 throw Exception("Unable to pack packet");
 378
 379                                         unsigned short packet_pos_save = pos;
 380                                         pos += 2;
 381
 382                                         this->PackName(output, output_size, pos, rr.rdata);
 383
 384                                         s = htons(pos - packet_pos_save - 2);
 385                                         memcpy(&output[packet_pos_save], &s, 2);
 386                                         break;
 387                                 }
 388                                 default:
 389                                         break;
 390                         }
 391                 }
 392
 393                 return pos;
 394         }
 395 };
 396
 397 class MyManager : public Manager, public Timer, public EventHandler
 398 {
 399         typedef TR1NS::unordered_map<Question, Query, Question::hash> cache_map;
 400         cache_map cache;
 401
 402         irc::sockets::sockaddrs myserver;
 403
 404         static bool IsExpired(const Query& record, time_t now = ServerInstance->Time())
 405         {
 406                 const ResourceRecord& req = record.answers[0];
 407                 return (req.created + static_cast<time_t>(req.ttl) < now);
 408         }
 409
 410         /** Check the DNS cache to see if request can be handled by a cached result
 411          * @return true if a cached result was found.
 412          */
 413         bool CheckCache(DNS::Request* req, const DNS::Question& question)
 414         {
 415                 ServerInstance->Logs->Log(MODNAME, LOG_SPARSE, "cache: Checking cache for " + question.name);
 416
 417                 cache_map::iterator it = this->cache.find(question);
 418                 if (it == this->cache.end())
 419                         return false;
 420
 421                 Query& record = it->second;
 422                 if (IsExpired(record))
 423                 {
 424                         this->cache.erase(it);
 425                         return false;
 426                 }
 427
 428                 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "cache: Using cached result for " + question.name);
 429                 record.cached = true;
 430                 req->OnLookupComplete(&record);
 431                 return true;
 432         }
 433
 434         /** Add a record to the dns cache
 435          * @param r The record
 436          */
 437         void AddCache(Query& r)
 438         {
 439                 const ResourceRecord& rr = r.answers[0];
 440                 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "cache: added cache for " + rr.name + " -> " + rr.rdata + " ttl: " + ConvToStr(rr.ttl));
 441                 this->cache[r.questions[0]] = r;
 442         }
 443
 444  public:
 445         DNS::Request* requests[MAX_REQUEST_ID];
 446
 447         MyManager(Module* c) : Manager(c), Timer(3600, true)
 448         {
 449                 for (int i = 0; i < MAX_REQUEST_ID; ++i)
 450                         requests[i] = NULL;
 451                 ServerInstance->Timers.AddTimer(this);
 452         }
 453
 454         ~MyManager()
 455         {
 456                 for (int i = 0; i < MAX_REQUEST_ID; ++i)
 457                 {
 458                         DNS::Request* request = requests[i];
 459                         if (!request)
 460                                 continue;
 461
 462                         Query rr(*request);
 463                         rr.error = ERROR_UNKNOWN;
 464                         request->OnError(&rr);
 465
 466                         delete request;
 467                 }
 468         }
 469
 470         void Process(DNS::Request* req)
 471         {
 472                 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Processing request to lookup " + req->name + " of type " + ConvToStr(req->type) + " to " + this->myserver.addr());
 473
 474                 /* Create an id */
 475                 unsigned int tries = 0;
 476                 int id;
 477                 do
 478                 {
 479                         id = ServerInstance->GenRandomInt(DNS::MAX_REQUEST_ID);
 480
 481                         if (++tries == DNS::MAX_REQUEST_ID*5)
 482                         {
 483                                 // If we couldn't find an empty slot this many times, do a sequential scan as a last
 484                                 // resort. If an empty slot is found that way, go on, otherwise throw an exception
 485                                 id = -1;
 486                                 for (unsigned int i = 0; i < DNS::MAX_REQUEST_ID; i++)
 487                                 {
 488                                         if (!this->requests[i])
 489                                         {
 490                                                 id = i;
 491                                                 break;
 492                                         }
 493                                 }
 494
 495                                 if (id == -1)
 496                                         throw Exception("DNS: All ids are in use");
 497
 498                                 break;
 499                         }
 500                 }
 501                 while (this->requests[id]);
 502
 503                 req->id = id;
 504                 this->requests[req->id] = req;
 505
 506                 Packet p;
 507                 p.flags = QUERYFLAGS_RD;
 508                 p.id = req->id;
 509                 p.questions.push_back(*req);
 510
 511                 unsigned char buffer[524];
 512                 unsigned short len = p.Pack(buffer, sizeof(buffer));
 513
 514                 /* Note that calling Pack() above can actually change the contents of p.questions[0].name, if the query is a PTR,
 515                  * to contain the value that would be in the DNS cache, which is why this is here.
 516                  */
 517                 if (req->use_cache && this->CheckCache(req, p.questions[0]))
 518                 {
 519                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Using cached result");
 520                         delete req;
 521                         return;
 522                 }
 523
 524                 if (SocketEngine::SendTo(this, buffer, len, 0, &this->myserver.sa, this->myserver.sa_size()) != len)
 525                         throw Exception("DNS: Unable to send query");
 526         }
 527
 528         void RemoveRequest(DNS::Request* req)
 529         {
 530                 this->requests[req->id] = NULL;
 531         }
 532
 533         std::string GetErrorStr(Error e)
 534         {
 535                 switch (e)
 536                 {
 537                         case ERROR_UNLOADED:
 538                                 return "Module is unloading";
 539                         case ERROR_TIMEDOUT:
 540                                 return "Request timed out";
 541                         case ERROR_NOT_AN_ANSWER:
 542                         case ERROR_NONSTANDARD_QUERY:
 543                         case ERROR_FORMAT_ERROR:
 544                                 return "Malformed answer";
 545                         case ERROR_SERVER_FAILURE:
 546                         case ERROR_NOT_IMPLEMENTED:
 547                         case ERROR_REFUSED:
 548                         case ERROR_INVALIDTYPE:
 549                                 return "Nameserver failure";
 550                         case ERROR_DOMAIN_NOT_FOUND:
 551                         case ERROR_NO_RECORDS:
 552                                 return "Domain not found";
 553                         case ERROR_NONE:
 554                         case ERROR_UNKNOWN:
 555                         default:
 556                                 return "Unknown error";
 557                 }
 558         }
 559
 560         void OnEventHandlerError(int errcode) CXX11_OVERRIDE
 561         {
 562                 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "UDP socket got an error event");
 563         }
 564
 565         void OnEventHandlerRead() CXX11_OVERRIDE
 566         {
 567                 unsigned char buffer[524];
 568                 irc::sockets::sockaddrs from;
 569                 socklen_t x = sizeof(from);
 570
 571                 int length = SocketEngine::RecvFrom(this, buffer, sizeof(buffer), 0, &from.sa, &x);
 572
 573                 if (length < Packet::HEADER_LENGTH)
 574                         return;
 575
 576                 if (myserver != from)
 577                 {
 578                         std::string server1 = from.str();
 579                         std::string server2 = myserver.str();
 580                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Got a result from the wrong server! Bad NAT or DNS forging attempt? '%s' != '%s'",
 581                                 server1.c_str(), server2.c_str());
 582                         return;
 583                 }
 584
 585                 Packet recv_packet;
 586
 587                 try
 588                 {
 589                         recv_packet.Fill(buffer, length);
 590                 }
 591                 catch (Exception& ex)
 592                 {
 593                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, ex.GetReason());
 594                         return;
 595                 }
 596
 597                 DNS::Request* request = this->requests[recv_packet.id];
 598                 if (request == NULL)
 599                 {
 600                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Received an answer for something we didn't request");
 601                         return;
 602                 }
 603
 604                 if (recv_packet.flags & QUERYFLAGS_OPCODE)
 605                 {
 606                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Received a nonstandard query");
 607                         ServerInstance->stats.DnsBad++;
 608                         recv_packet.error = ERROR_NONSTANDARD_QUERY;
 609                         request->OnError(&recv_packet);
 610                 }
 611                 else if (recv_packet.flags & QUERYFLAGS_RCODE)
 612                 {
 613                         Error error = ERROR_UNKNOWN;
 614
 615                         switch (recv_packet.flags & QUERYFLAGS_RCODE)
 616                         {
 617                                 case 1:
 618                                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "format error");
 619                                         error = ERROR_FORMAT_ERROR;
 620                                         break;
 621                                 case 2:
 622                                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "server error");
 623                                         error = ERROR_SERVER_FAILURE;
 624                                         break;
 625                                 case 3:
 626                                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "domain not found");
 627                                         error = ERROR_DOMAIN_NOT_FOUND;
 628                                         break;
 629                                 case 4:
 630                                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "not implemented");
 631                                         error = ERROR_NOT_IMPLEMENTED;
 632                                         break;
 633                                 case 5:
 634                                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "refused");
 635                                         error = ERROR_REFUSED;
 636                                         break;
 637                                 default:
 638                                         break;
 639                         }
 640
 641                         ServerInstance->stats.DnsBad++;
 642                         recv_packet.error = error;
 643                         request->OnError(&recv_packet);
 644                 }
 645                 else if (recv_packet.questions.empty() || recv_packet.answers.empty())
 646                 {
 647                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "No resource records returned");
 648                         ServerInstance->stats.DnsBad++;
 649                         recv_packet.error = ERROR_NO_RECORDS;
 650                         request->OnError(&recv_packet);
 651                 }
 652                 else
 653                 {
 654                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Lookup complete for " + request->name);
 655                         ServerInstance->stats.DnsGood++;
 656                         request->OnLookupComplete(&recv_packet);
 657                         this->AddCache(recv_packet);
 658                 }
 659
 660                 ServerInstance->stats.Dns++;
 661
 662                 /* Request's destructor removes it from the request map */
 663                 delete request;
 664         }
 665
 666         bool Tick(time_t now)
 667         {
 668                 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "cache: purging DNS cache");
 669
 670                 for (cache_map::iterator it = this->cache.begin(); it != this->cache.end(); )
 671                 {
 672                         const Query& query = it->second;
 673                         if (IsExpired(query, now))
 674                                 this->cache.erase(it++);
 675                         else
 676                                 ++it;
 677                 }
 678                 return true;
 679         }
 680
 681         void Rehash(const std::string& dnsserver)
 682         {
 683                 if (this->GetFd() > -1)
 684                 {
 685                         SocketEngine::Shutdown(this, 2);
 686                         SocketEngine::Close(this);
 687
 688                         /* Remove expired entries from the cache */
 689                         this->Tick(ServerInstance->Time());
 690                 }
 691
 692                 irc::sockets::aptosa(dnsserver, DNS::PORT, myserver);
 693
 694                 /* Initialize mastersocket */
 695                 int s = socket(myserver.sa.sa_family, SOCK_DGRAM, 0);
 696                 this->SetFd(s);
 697
 698                 /* Have we got a socket? */
 699                 if (this->GetFd() != -1)
 700                 {
 701                         SocketEngine::SetReuse(s);
 702                         SocketEngine::NonBlocking(s);
 703
 704                         irc::sockets::sockaddrs bindto;
 705                         memset(&bindto, 0, sizeof(bindto));
 706                         bindto.sa.sa_family = myserver.sa.sa_family;
 707
 708                         if (SocketEngine::Bind(this->GetFd(), bindto) < 0)
 709                         {
 710                                 /* Failed to bind */
 711                                 ServerInstance->Logs->Log(MODNAME, LOG_SPARSE, "Error binding dns socket - hostnames will NOT resolve");
 712                                 SocketEngine::Close(this->GetFd());
 713                                 this->SetFd(-1);
 714                         }
 715                         else if (!SocketEngine::AddFd(this, FD_WANT_POLL_READ | FD_WANT_NO_WRITE))
 716                         {
 717                                 ServerInstance->Logs->Log(MODNAME, LOG_SPARSE, "Internal error starting DNS - hostnames will NOT resolve.");
 718                                 SocketEngine::Close(this->GetFd());
 719                                 this->SetFd(-1);
 720                         }
 721                 }
 722                 else
 723                 {
 724                         ServerInstance->Logs->Log(MODNAME, LOG_SPARSE, "Error creating DNS socket - hostnames will NOT resolve");
 725                 }
 726         }
 727 };
 728
 729 class ModuleDNS : public Module
 730 {
 731         MyManager manager;
 732         std::string DNSServer;
 733
 734         void FindDNSServer()
 735         {
 736 #ifdef _WIN32
 737                 // attempt to look up their nameserver from the system
 738                 ServerInstance->Logs->Log("CONFIG", LOG_DEFAULT, "WARNING: <dns:server> not defined, attempting to find a working server in the system settings...");
 739
 740                 PFIXED_INFO pFixedInfo;
 741                 DWORD dwBufferSize = sizeof(FIXED_INFO);
 742                 pFixedInfo = (PFIXED_INFO) HeapAlloc(GetProcessHeap(), 0, sizeof(FIXED_INFO));
 743
 744                 if (pFixedInfo)
 745                 {
 746                         if (GetNetworkParams(pFixedInfo, &dwBufferSize) == ERROR_BUFFER_OVERFLOW)
 747                         {
 748                                 HeapFree(GetProcessHeap(), 0, pFixedInfo);
 749                                 pFixedInfo = (PFIXED_INFO) HeapAlloc(GetProcessHeap(), 0, dwBufferSize);
 750                         }
 751
 752                         if (pFixedInfo)
 753                         {
 754                                 if (GetNetworkParams(pFixedInfo, &dwBufferSize) == NO_ERROR)
 755                                         DNSServer = pFixedInfo->DnsServerList.IpAddress.String;
 756
 757                                 HeapFree(GetProcessHeap(), 0, pFixedInfo);
 758                         }
 759
 760                         if (!DNSServer.empty())
 761                         {
 762                                 ServerInstance->Logs->Log("CONFIG", LOG_DEFAULT, "<dns:server> set to '%s' as first active resolver in the system settings.", DNSServer.c_str());
 763                                 return;
 764                         }
 765                 }
 766
 767                 ServerInstance->Logs->Log("CONFIG", LOG_DEFAULT, "No viable nameserver found! Defaulting to nameserver '127.0.0.1'!");
 768 #else
 769                 // attempt to look up their nameserver from /etc/resolv.conf
 770                 ServerInstance->Logs->Log("CONFIG", LOG_DEFAULT, "WARNING: <dns:server> not defined, attempting to find working server in /etc/resolv.conf...");
 771
 772                 std::ifstream resolv("/etc/resolv.conf");
 773
 774                 while (resolv >> DNSServer)
 775                 {
 776                         if (DNSServer == "nameserver")
 777                         {
 778                                 resolv >> DNSServer;
 779                                 if (DNSServer.find_first_not_of("0123456789.") == std::string::npos)
 780                                 {
 781                                         ServerInstance->Logs->Log("CONFIG", LOG_DEFAULT, "<dns:server> set to '%s' as first resolver in /etc/resolv.conf.",DNSServer.c_str());
 782                                         return;
 783                                 }
 784                         }
 785                 }
 786
 787                 ServerInstance->Logs->Log("CONFIG", LOG_DEFAULT, "/etc/resolv.conf contains no viable nameserver entries! Defaulting to nameserver '127.0.0.1'!");
 788 #endif
 789                 DNSServer = "127.0.0.1";
 790         }
 791
 792  public:
 793         ModuleDNS() : manager(this)
 794         {
 795         }
 796
 797         void ReadConfig(ConfigStatus& status) CXX11_OVERRIDE
 798         {
 799                 std::string oldserver = DNSServer;
 800                 DNSServer = ServerInstance->Config->ConfValue("dns")->getString("server");
 801                 if (DNSServer.empty())
 802                         FindDNSServer();
 803
 804                 if (oldserver != DNSServer)
 805                         this->manager.Rehash(DNSServer);
 806         }
 807
 808         void OnUnloadModule(Module* mod)
 809         {
 810                 for (int i = 0; i < MAX_REQUEST_ID; ++i)
 811                 {
 812                         DNS::Request* req = this->manager.requests[i];
 813                         if (!req)
 814                                 continue;
 815
 816                         if (req->creator == mod)
 817                         {
 818                                 Query rr(*req);
 819                                 rr.error = ERROR_UNLOADED;
 820                                 req->OnError(&rr);
 821
 822                                 delete req;
 823                         }
 824                 }
 825         }
 826
 827         Version GetVersion()
 828         {
 829                 return Version("DNS support", VF_CORE|VF_VENDOR);
 830         }
 831 };
 832
 833 MODULE_INIT(ModuleDNS)
 834