src/dns.cpp

   1 /*       +------------------------------------+
   2  *       | Inspire Internet Relay Chat Daemon |
   3  *       +------------------------------------+
   4  *
   5  *  InspIRCd: (C) 2002-2007 InspIRCd Development Team
   6  * See: http://www.inspircd.org/wiki/index.php/Credits
   7  *
   8  * This program is free but copyrighted software; see
   9  *            the file COPYING for details.
  10  *
  11  * ---------------------------------------------------
  12  */
  13
  14 /*
  15 dns.cpp - Nonblocking DNS functions.
  16 Very very loosely based on the firedns library,
  17 Copyright (C) 2002 Ian Gulliver. This file is no
  18 longer anything like firedns, there are many major
  19 differences between this code and the original.
  20 Please do not assume that firedns works like this,
  21 looks like this, walks like this or tastes like this.
  22 */
  23
  24 #ifndef WIN32
  25 #include <sys/types.h>
  26 #include <sys/socket.h>
  27 #include <errno.h>
  28 #include <netinet/in.h>
  29 #include <arpa/inet.h>
  30 #else
  31 #include "inspircd_win32wrapper.h"
  32 #endif
  33
  34 #include "dns.h"
  35 #include "inspircd.h"
  36 #include "socketengine.h"
  37 #include "configreader.h"
  38 #include "socket.h"
  39
  40 using irc::sockets::insp_inaddr;
  41 using irc::sockets::insp_ntoa;
  42 using irc::sockets::insp_aton;
  43 using irc::sockets::OpenTCPSocket;
  44
  45 /** Masks to mask off the responses we get from the DNSRequest methods
  46  */
  47 enum QueryInfo
  48 {
  49         ERROR_MASK      = 0x10000       /* Result is an error */
  50 };
  51
  52 /** Flags which can be ORed into a request or reply for different meanings
  53  */
  54 enum QueryFlags
  55 {
  56         FLAGS_MASK_RD           = 0x01, /* Recursive */
  57         FLAGS_MASK_TC           = 0x02,
  58         FLAGS_MASK_AA           = 0x04, /* Authoritative */
  59         FLAGS_MASK_OPCODE       = 0x78,
  60         FLAGS_MASK_QR           = 0x80,
  61         FLAGS_MASK_RCODE        = 0x0F, /* Request */
  62         FLAGS_MASK_Z            = 0x70,
  63         FLAGS_MASK_RA           = 0x80
  64 };
  65
  66
  67 /** Represents a dns resource record (rr)
  68  */
  69 struct ResourceRecord
  70 {
  71         QueryType       type;           /* Record type */
  72         unsigned int    rr_class;       /* Record class */
  73         unsigned long   ttl;            /* Time to live */
  74         unsigned int    rdlength;       /* Record length */
  75 };
  76
  77 /** Represents a dns request/reply header, and its payload as opaque data.
  78  */
  79 class DNSHeader
  80 {
  81  public:
  82         unsigned char   id[2];          /* Request id */
  83         unsigned int    flags1;         /* Flags */
  84         unsigned int    flags2;         /* Flags */
  85         unsigned int    qdcount;
  86         unsigned int    ancount;        /* Answer count */
  87         unsigned int    nscount;        /* Nameserver count */
  88         unsigned int    arcount;
  89         unsigned char   payload[512];   /* Packet payload */
  90 };
  91
  92 class DNSRequest
  93 {
  94  public:
  95         unsigned char   id[2];          /* Request id */
  96         unsigned char*  res;            /* Result processing buffer */
  97         unsigned int    rr_class;       /* Request class */
  98         QueryType       type;           /* Request type */
  99         DNS*            dnsobj;         /* DNS caller (where we get our FD from) */
 100         unsigned long   ttl;            /* Time to live */
 101         std::string     orig;           /* Original requested name/ip */
 102
 103         DNSRequest(InspIRCd* Instance, DNS* dns, int id, const std::string &original);
 104         ~DNSRequest();
 105         DNSInfo ResultIsReady(DNSHeader &h, int length);
 106         int SendRequests(const DNSHeader *header, const int length, QueryType qt);
 107 };
 108
 109 class CacheTimer : public InspTimer
 110 {
 111  private:
 112         InspIRCd* ServerInstance;
 113         DNS* dns;
 114  public:
 115         CacheTimer(InspIRCd* Instance, DNS* thisdns)
 116                 : InspTimer(3600, Instance->Time(), true), ServerInstance(Instance), dns(thisdns) { }
 117
 118         virtual void Tick(time_t TIME)
 119         {
 120                 dns->PruneCache();
 121         }
 122 };
 123
 124 class RequestTimeout : public InspTimer
 125 {
 126         InspIRCd* ServerInstance;
 127         DNSRequest* watch;
 128         int watchid;
 129  public:
 130         RequestTimeout(unsigned long n, InspIRCd* SI, DNSRequest* watching, int id) : InspTimer(n, time(NULL)), ServerInstance(SI), watch(watching), watchid(id)
 131         {
 132         }
 133
 134         void Tick(time_t TIME)
 135         {
 136                 if (ServerInstance->Res->requests[watchid] == watch)
 137                 {
 138                         /* Still exists, whack it */
 139                         if (ServerInstance->Res->Classes[watchid])
 140                         {
 141                                 ServerInstance->Res->Classes[watchid]->OnError(RESOLVER_TIMEOUT, "Request timed out");
 142                                 delete ServerInstance->Res->Classes[watchid];
 143                                 ServerInstance->Res->Classes[watchid] = NULL;
 144                         }
 145                         ServerInstance->Res->requests[watchid] = NULL;
 146                         DELETE(watch);
 147                         return;
 148                 }
 149         }
 150 };
 151
 152 /* Allocate the processing buffer */
 153 DNSRequest::DNSRequest(InspIRCd* Instance, DNS* dns, int id, const std::string &original) : dnsobj(dns)
 154 {
 155         res = new unsigned char[512];
 156         *res = 0;
 157         orig = original;
 158         RequestTimeout* RT = new RequestTimeout(Instance->Config->dns_timeout ? Instance->Config->dns_timeout : 5, Instance, this, id);
 159         Instance->Timers->AddTimer(RT); /* The timer manager frees this */
 160 }
 161
 162 /* Deallocate the processing buffer */
 163 DNSRequest::~DNSRequest()
 164 {
 165         delete[] res;
 166 }
 167
 168 /** Fill a ResourceRecord class based on raw data input */
 169 inline void DNS::FillResourceRecord(ResourceRecord* rr, const unsigned char *input)
 170 {
 171         rr->type = (QueryType)((input[0] << 8) + input[1]);
 172         rr->rr_class = (input[2] << 8) + input[3];
 173         rr->ttl = (input[4] << 24) + (input[5] << 16) + (input[6] << 8) + input[7];
 174         rr->rdlength = (input[8] << 8) + input[9];
 175 }
 176
 177 /** Fill a DNSHeader class based on raw data input of a given length */
 178 inline void DNS::FillHeader(DNSHeader *header, const unsigned char *input, const int length)
 179 {
 180         header->id[0] = input[0];
 181         header->id[1] = input[1];
 182         header->flags1 = input[2];
 183         header->flags2 = input[3];
 184         header->qdcount = (input[4] << 8) + input[5];
 185         header->ancount = (input[6] << 8) + input[7];
 186         header->nscount = (input[8] << 8) + input[9];
 187         header->arcount = (input[10] << 8) + input[11];
 188         memcpy(header->payload,&input[12],length);
 189 }
 190
 191 /** Empty a DNSHeader class out into raw data, ready for transmission */
 192 inline void DNS::EmptyHeader(unsigned char *output, const DNSHeader *header, const int length)
 193 {
 194         output[0] = header->id[0];
 195         output[1] = header->id[1];
 196         output[2] = header->flags1;
 197         output[3] = header->flags2;
 198         output[4] = header->qdcount >> 8;
 199         output[5] = header->qdcount & 0xFF;
 200         output[6] = header->ancount >> 8;
 201         output[7] = header->ancount & 0xFF;
 202         output[8] = header->nscount >> 8;
 203         output[9] = header->nscount & 0xFF;
 204         output[10] = header->arcount >> 8;
 205         output[11] = header->arcount & 0xFF;
 206         memcpy(&output[12],header->payload,length);
 207 }
 208
 209 /** Send requests we have previously built down the UDP socket */
 210 int DNSRequest::SendRequests(const DNSHeader *header, const int length, QueryType qt)
 211 {
 212         unsigned char payload[sizeof(DNSHeader)];
 213
 214         this->rr_class = 1;
 215         this->type = qt;
 216
 217         DNS::EmptyHeader(payload,header,length);
 218
 219 #ifdef IPV6
 220         if (this->dnsobj->socketfamily == AF_INET6)
 221         {
 222                 sockaddr_in6 addr;
 223                 memset(&addr,0,sizeof(addr));
 224                 memcpy(&addr.sin6_addr,&dnsobj->myserver6,sizeof(addr.sin6_addr));
 225                 addr.sin6_family = AF_INET6;
 226                 addr.sin6_port = htons(DNS::QUERY_PORT);
 227                 if (sendto(dnsobj->GetFd(), payload, length + 12, 0, (sockaddr *) &addr, sizeof(addr)) != length+12)
 228                         return -1;
 229         }
 230         else
 231         {
 232                 sockaddr_in addr;
 233                 memset(&addr,0,sizeof(addr));
 234                 memcpy(&addr.sin_addr.s_addr,&dnsobj->myserver4,sizeof(addr.sin_addr));
 235                 addr.sin_family = AF_INET;
 236                 addr.sin_port = htons(DNS::QUERY_PORT);
 237                 if (sendto(dnsobj->GetFd(), payload, length + 12, 0, (sockaddr *) &addr, sizeof(addr)) != length+12)
 238                         return -1;
 239         }
 240 #else
 241         sockaddr_in addr;
 242         memset(&addr,0,sizeof(addr));
 243         memcpy(&addr.sin_addr.s_addr, &dnsobj->myserver4, sizeof(addr.sin_addr));
 244         addr.sin_family = AF_INET;
 245         addr.sin_port = htons(DNS::QUERY_PORT);
 246         if (sendto(dnsobj->GetFd(), (const char*)payload, length + 12, 0, (sockaddr *) &addr, sizeof(addr)) != length+12)
 247                 return -1;
 248 #endif
 249
 250         return 0;
 251 }
 252
 253 /** Add a query with a predefined header, and allocate an ID for it. */
 254 DNSRequest* DNS::AddQuery(DNSHeader *header, int &id, const char* original)
 255 {
 256         /* Is the DNS connection down? */
 257         if (this->GetFd() == -1)
 258                 return NULL;
 259
 260         /* Create an id */
 261         id = this->PRNG() & DNS::MAX_REQUEST_ID;
 262
 263         /* If this id is already 'in flight', pick another. */
 264         while (requests[id])
 265                 id = this->PRNG() & DNS::MAX_REQUEST_ID;
 266
 267         DNSRequest* req = new DNSRequest(ServerInstance, this, id, original);
 268
 269         header->id[0] = req->id[0] = id >> 8;
 270         header->id[1] = req->id[1] = id & 0xFF;
 271         header->flags1 = FLAGS_MASK_RD;
 272         header->flags2 = 0;
 273         header->qdcount = 1;
 274         header->ancount = 0;
 275         header->nscount = 0;
 276         header->arcount = 0;
 277
 278         /* At this point we already know the id doesnt exist,
 279          * so there needs to be no second check for the ::end()
 280          */
 281         requests[id] = req;
 282
 283         /* According to the C++ spec, new never returns NULL. */
 284         return req;
 285 }
 286
 287 int DNS::ClearCache()
 288 {
 289         /* This ensures the buckets are reset to sane levels */
 290         int rv = this->cache->size();
 291         delete this->cache;
 292         this->cache = new dnscache();
 293         return rv;
 294 }
 295
 296 int DNS::PruneCache()
 297 {
 298         int n = 0;
 299         dnscache* newcache = new dnscache();
 300         for (dnscache::iterator i = this->cache->begin(); i != this->cache->end(); i++)
 301                 /* Dont include expired items (theres no point) */
 302                 if (i->second.CalcTTLRemaining())
 303                         newcache->insert(*i);
 304                 else
 305                         n++;
 306
 307         delete this->cache;
 308         this->cache = newcache;
 309         return n;
 310 }
 311
 312 void DNS::Rehash()
 313 {
 314         ip6munge = false;
 315         int portpass = 0;
 316
 317         if (this->GetFd() > -1)
 318         {
 319                 if (ServerInstance && ServerInstance->SE)
 320                         ServerInstance->SE->DelFd(this);
 321                 shutdown(this->GetFd(), 2);
 322                 close(this->GetFd());
 323                 this->SetFd(-1);
 324
 325                 /* Rehash the cache */
 326                 this->PruneCache();
 327         }
 328         else
 329         {
 330                 /* Create initial dns cache */
 331                 this->cache = new dnscache();
 332         }
 333
 334         if ((strstr(ServerInstance->Config->DNSServer,"::ffff:") == (char*)&ServerInstance->Config->DNSServer) ||  (strstr(ServerInstance->Config->DNSServer,"::FFFF:") == (char*)&ServerInstance->Config->DNSServer))
 335         {
 336                 ServerInstance->Log(DEFAULT,"WARNING: Using IPv4 addresses over IPv6 forces some DNS checks to be disabled.");
 337                 ServerInstance->Log(DEFAULT,"         This should not cause a problem, however it is recommended you migrate");
 338                 ServerInstance->Log(DEFAULT,"         to a true IPv6 environment.");
 339                 this->ip6munge = true;
 340         }
 341
 342         this->socketfamily = AF_INET;
 343 #ifdef IPV6
 344         if (strchr(ServerInstance->Config->DNSServer,':'))
 345         {
 346                 this->socketfamily = AF_INET6;
 347                 inet_pton(AF_INET6, ServerInstance->Config->DNSServer, &this->myserver6);
 348         }
 349         else
 350         {
 351                 inet_aton(ServerInstance->Config->DNSServer, &this->myserver4);
 352                 portpass = -1;
 353         }
 354 #else
 355         inet_aton(ServerInstance->Config->DNSServer, &this->myserver4);
 356 #endif
 357
 358         /* Initialize mastersocket */
 359         int s = OpenTCPSocket(ServerInstance->Config->DNSServer, SOCK_DGRAM);
 360         this->SetFd(s);
 361
 362         /* Have we got a socket and is it nonblocking? */
 363         if (this->GetFd() != -1)
 364         {
 365                 /* Bind the port - port 0 INADDR_ANY */
 366                 if (!ServerInstance->BindSocket(this->GetFd(), portpass, "", false))
 367                 {
 368                         /* Failed to bind */
 369                         shutdown(this->GetFd(),2);
 370                         close(this->GetFd());
 371                         this->SetFd(-1);
 372                 }
 373
 374                 if (this->GetFd() >= 0)
 375                 {
 376                         /* Hook the descriptor into the socket engine */
 377                         if (ServerInstance && ServerInstance->SE)
 378                         {
 379                                 if (!ServerInstance->SE->AddFd(this))
 380                                 {
 381                                         ServerInstance->Log(DEFAULT,"Internal error starting DNS - hostnames will NOT resolve.");
 382                                         shutdown(this->GetFd(),2);
 383                                         close(this->GetFd());
 384                                         this->SetFd(-1);
 385                                 }
 386                         }
 387                 }
 388         }
 389 }
 390
 391 /** Initialise the DNS UDP socket so that we can send requests */
 392 DNS::DNS(InspIRCd* Instance) : ServerInstance(Instance)
 393 {
 394         /* Clear the Resolver class table */
 395         memset(Classes,0,sizeof(Classes));
 396
 397         /* Clear the requests class table */
 398         memset(requests,0,sizeof(requests));
 399
 400         /* Set the id of the next request to 0
 401          */
 402         currid = 0;
 403
 404         /* DNS::Rehash() sets this to a valid ptr
 405          */
 406         this->cache = NULL;
 407
 408         /* Again, DNS::Rehash() sets this to a
 409          * valid value
 410          */
 411         this->SetFd(-1);
 412
 413         /* Actually read the settings
 414          */
 415         this->Rehash();
 416
 417         this->PruneTimer = new CacheTimer(ServerInstance, this);
 418
 419         ServerInstance->Timers->AddTimer(this->PruneTimer);
 420 }
 421
 422 /** Build a payload to be placed after the header, based upon input data, a resource type, a class and a pointer to a buffer */
 423 int DNS::MakePayload(const char * const name, const QueryType rr, const unsigned short rr_class, unsigned char * const payload)
 424 {
 425         short payloadpos = 0;
 426         const char* tempchr, *tempchr2 = name;
 427         unsigned short length;
 428
 429         /* split name up into labels, create query */
 430         while ((tempchr = strchr(tempchr2,'.')) != NULL)
 431         {
 432                 length = tempchr - tempchr2;
 433                 if (payloadpos + length + 1 > 507)
 434                         return -1;
 435                 payload[payloadpos++] = length;
 436                 memcpy(&payload[payloadpos],tempchr2,length);
 437                 payloadpos += length;
 438                 tempchr2 = &tempchr[1];
 439         }
 440         length = strlen(tempchr2);
 441         if (length)
 442         {
 443                 if (payloadpos + length + 2 > 507)
 444                         return -1;
 445                 payload[payloadpos++] = length;
 446                 memcpy(&payload[payloadpos],tempchr2,length);
 447                 payloadpos += length;
 448                 payload[payloadpos++] = 0;
 449         }
 450         if (payloadpos > 508)
 451                 return -1;
 452         length = htons(rr);
 453         memcpy(&payload[payloadpos],&length,2);
 454         length = htons(rr_class);
 455         memcpy(&payload[payloadpos + 2],&length,2);
 456         return payloadpos + 4;
 457 }
 458
 459 /** Start lookup of an hostname to an IP address */
 460 int DNS::GetIP(const char *name)
 461 {
 462         DNSHeader h;
 463         int id;
 464         int length;
 465
 466         if ((length = this->MakePayload(name, DNS_QUERY_A, 1, (unsigned char*)&h.payload)) == -1)
 467                 return -1;
 468
 469         DNSRequest* req = this->AddQuery(&h, id, name);
 470
 471         if ((!req) || (req->SendRequests(&h, length, DNS_QUERY_A) == -1))
 472                 return -1;
 473
 474         return id;
 475 }
 476
 477 /** Start lookup of an hostname to an IPv6 address */
 478 int DNS::GetIP6(const char *name)
 479 {
 480         DNSHeader h;
 481         int id;
 482         int length;
 483
 484         if ((length = this->MakePayload(name, DNS_QUERY_AAAA, 1, (unsigned char*)&h.payload)) == -1)
 485                 return -1;
 486
 487         DNSRequest* req = this->AddQuery(&h, id, name);
 488
 489         if ((!req) || (req->SendRequests(&h, length, DNS_QUERY_AAAA) == -1))
 490                 return -1;
 491
 492         return id;
 493 }
 494
 495 /** Start lookup of a cname to another name */
 496 int DNS::GetCName(const char *alias)
 497 {
 498         DNSHeader h;
 499         int id;
 500         int length;
 501
 502         if ((length = this->MakePayload(alias, DNS_QUERY_CNAME, 1, (unsigned char*)&h.payload)) == -1)
 503                 return -1;
 504
 505         DNSRequest* req = this->AddQuery(&h, id, alias);
 506
 507         if ((!req) || (req->SendRequests(&h, length, DNS_QUERY_CNAME) == -1))
 508                 return -1;
 509
 510         return id;
 511 }
 512
 513 /** Start lookup of an IP address to a hostname */
 514 int DNS::GetName(const insp_inaddr *ip)
 515 {
 516         char query[128];
 517         DNSHeader h;
 518         int id;
 519         int length;
 520
 521 #ifdef IPV6
 522         unsigned char* c = (unsigned char*)&ip->s6_addr;
 523         if (c[0] == 0 && c[1] == 0 && c[2] == 0 && c[3] == 0 &&
 524             c[4] == 0 && c[5] == 0 && c[6] == 0 && c[7] == 0 &&
 525             c[8] == 0 && c[9] == 0 && c[10] == 0xFF && c[11] == 0xFF)
 526                 sprintf(query,"%d.%d.%d.%d.in-addr.arpa",c[15],c[14],c[13],c[12]);
 527         else
 528                 DNS::MakeIP6Int(query, (in6_addr*)ip);
 529 #else
 530         unsigned char* c = (unsigned char*)&ip->s_addr;
 531         sprintf(query,"%d.%d.%d.%d.in-addr.arpa",c[3],c[2],c[1],c[0]);
 532 #endif
 533
 534         if ((length = this->MakePayload(query, DNS_QUERY_PTR, 1, (unsigned char*)&h.payload)) == -1)
 535                 return -1;
 536
 537         DNSRequest* req = this->AddQuery(&h, id, insp_ntoa(*ip));
 538
 539         if ((!req) || (req->SendRequests(&h, length, DNS_QUERY_PTR) == -1))
 540                 return -1;
 541
 542         return id;
 543 }
 544
 545 /** Start lookup of an IP address to a hostname */
 546 int DNS::GetNameForce(const char *ip, ForceProtocol fp)
 547 {
 548         char query[128];
 549         DNSHeader h;
 550         int id;
 551         int length;
 552 #ifdef SUPPORT_IP6LINKS
 553         if (fp == PROTOCOL_IPV6)
 554         {
 555                 in6_addr i;
 556                 if (inet_pton(AF_INET6, ip, &i) > 0)
 557                 {
 558                         DNS::MakeIP6Int(query, &i);
 559                 }
 560                 else
 561                         /* Invalid IP address */
 562                         return -1;
 563         }
 564         else
 565 #endif
 566         {
 567                 in_addr i;
 568                 if (inet_aton(ip, &i))
 569                 {
 570                         unsigned char* c = (unsigned char*)&i.s_addr;
 571                         sprintf(query,"%d.%d.%d.%d.in-addr.arpa",c[3],c[2],c[1],c[0]);
 572                 }
 573                 else
 574                         /* Invalid IP address */
 575                         return -1;
 576         }
 577
 578         if ((length = this->MakePayload(query, DNS_QUERY_PTR, 1, (unsigned char*)&h.payload)) == -1)
 579                 return -1;
 580
 581         DNSRequest* req = this->AddQuery(&h, id, ip);
 582
 583         if ((!req) || (req->SendRequests(&h, length, DNS_QUERY_PTR) == -1))
 584                 return -1;
 585
 586         return id;
 587 }
 588
 589 /** Build an ipv6 reverse domain from an in6_addr
 590  */
 591 void DNS::MakeIP6Int(char* query, const in6_addr *ip)
 592 {
 593 #ifdef SUPPORT_IP6LINKS
 594         const char* hex = "0123456789abcdef";
 595         for (int index = 31; index >= 0; index--) /* for() loop steps twice per byte */
 596         {
 597                 if (index % 2)
 598                         /* low nibble */
 599                         *query++ = hex[ip->s6_addr[index / 2] & 0x0F];
 600                 else
 601                         /* high nibble */
 602                         *query++ = hex[(ip->s6_addr[index / 2] & 0xF0) >> 4];
 603                 *query++ = '.'; /* Seperator */
 604         }
 605         strcpy(query,"ip6.arpa"); /* Suffix the string */
 606 #else
 607         *query = 0;
 608 #endif
 609 }
 610
 611 /** Return the next id which is ready, and the result attached to it */
 612 DNSResult DNS::GetResult()
 613 {
 614         /* Fetch dns query response and decide where it belongs */
 615         DNSHeader header;
 616         DNSRequest *req;
 617         unsigned char buffer[sizeof(DNSHeader)];
 618         sockaddr* from = new sockaddr[2];
 619 #ifdef IPV6
 620         socklen_t x = this->socketfamily == AF_INET ? sizeof(sockaddr_in) : sizeof(sockaddr_in6);
 621 #else
 622         socklen_t x = sizeof(sockaddr_in);
 623 #endif
 624         const char* ipaddr_from;
 625         unsigned short int port_from = 0;
 626
 627         int length = recvfrom(this->GetFd(),(char*)buffer,sizeof(DNSHeader),0,from,&x);
 628
 629         /* Did we get the whole header? */
 630         if (length < 12)
 631         {
 632                 /* Nope - something screwed up. */
 633                 delete[] from;
 634                 return DNSResult(-1,"",0,"");
 635         }
 636
 637         /* Check wether the reply came from a different DNS
 638          * server to the one we sent it to, or the source-port
 639          * is not 53.
 640          * A user could in theory still spoof dns packets anyway
 641          * but this is less trivial than just sending garbage
 642          * to the client, which is possible without this check.
 643          *
 644          * -- Thanks jilles for pointing this one out.
 645          */
 646 #ifdef IPV6
 647         char nbuf[MAXBUF];
 648         if (this->socketfamily == AF_INET6)
 649         {
 650                 ipaddr_from = inet_ntop(AF_INET6, &((sockaddr_in6*)from)->sin6_addr, nbuf, sizeof(nbuf));
 651                 port_from = ntohs(((sockaddr_in6*)from)->sin6_port);
 652         }
 653         else
 654 #endif
 655         {
 656                 ipaddr_from = inet_ntoa(((sockaddr_in*)from)->sin_addr);
 657                 port_from = ntohs(((sockaddr_in*)from)->sin_port);
 658         }
 659
 660         delete[] from;
 661
 662         /* We cant perform this security check if you're using 4in6.
 663          * Tough luck to you, choose one or't other!
 664          */
 665         if (!ip6munge)
 666         {
 667                 if ((port_from != DNS::QUERY_PORT) || (strcasecmp(ipaddr_from, ServerInstance->Config->DNSServer)))
 668                 {
 669                         return DNSResult(-1,"",0,"");
 670                 }
 671         }
 672
 673         /* Put the read header info into a header class */
 674         DNS::FillHeader(&header,buffer,length - 12);
 675
 676         /* Get the id of this request.
 677          * Its a 16 bit value stored in two char's,
 678          * so we use logic shifts to create the value.
 679          */
 680         unsigned long this_id = header.id[1] + (header.id[0] << 8);
 681
 682         /* Do we have a pending request matching this id? */
 683         if (!requests[this_id])
 684         {
 685                 /* Somehow we got a DNS response for a request we never made... */
 686                 return DNSResult(-1,"",0,"");
 687         }
 688         else
 689         {
 690                 /* Remove the query from the list of pending queries */
 691                 req = requests[this_id];
 692                 requests[this_id] = NULL;
 693         }
 694
 695         /* Inform the DNSRequest class that it has a result to be read.
 696          * When its finished it will return a DNSInfo which is a pair of
 697          * unsigned char* resource record data, and an error message.
 698          */
 699         DNSInfo data = req->ResultIsReady(header, length);
 700         std::string resultstr;
 701
 702         /* Check if we got a result, if we didnt, its an error */
 703         if (data.first == NULL)
 704         {
 705                 /* An error.
 706                  * Mask the ID with the value of ERROR_MASK, so that
 707                  * the dns_deal_with_classes() function knows that its
 708                  * an error response and needs to be treated uniquely.
 709                  * Put the error message in the second field.
 710                  */
 711                 std::string ro = req->orig;
 712                 delete req;
 713                 return DNSResult(this_id | ERROR_MASK, data.second, 0, ro);
 714         }
 715         else
 716         {
 717                 unsigned long ttl = req->ttl;
 718                 char formatted[128];
 719
 720                 /* Forward lookups come back as binary data. We must format them into ascii */
 721                 switch (req->type)
 722                 {
 723                         case DNS_QUERY_A:
 724                                 snprintf(formatted,16,"%u.%u.%u.%u",data.first[0],data.first[1],data.first[2],data.first[3]);
 725                                 resultstr = formatted;
 726                         break;
 727
 728                         case DNS_QUERY_AAAA:
 729                         {
 730                                 snprintf(formatted,40,"%x:%x:%x:%x:%x:%x:%x:%x",
 731                                                 (ntohs(data.first[0]) + ntohs(data.first[1] << 8)),
 732                                                 (ntohs(data.first[2]) + ntohs(data.first[3] << 8)),
 733                                                 (ntohs(data.first[4]) + ntohs(data.first[5] << 8)),
 734                                                 (ntohs(data.first[6]) + ntohs(data.first[7] << 8)),
 735                                                 (ntohs(data.first[8]) + ntohs(data.first[9] << 8)),
 736                                                 (ntohs(data.first[10]) + ntohs(data.first[11] << 8)),
 737                                                 (ntohs(data.first[12]) + ntohs(data.first[13] << 8)),
 738                                                 (ntohs(data.first[14]) + ntohs(data.first[15] << 8)));
 739                                 char* c = strstr(formatted,":0:");
 740                                 if (c != NULL)
 741                                 {
 742                                         memmove(c+1,c+2,strlen(c+2) + 1);
 743                                         c += 2;
 744                                         while (memcmp(c,"0:",2) == 0)
 745                                                 memmove(c,c+2,strlen(c+2) + 1);
 746                                         if (memcmp(c,"0",2) == 0)
 747                                                 *c = 0;
 748                                         if (memcmp(formatted,"0::",3) == 0)
 749                                                 memmove(formatted,formatted + 1, strlen(formatted + 1) + 1);
 750                                 }
 751                                 resultstr = formatted;
 752
 753                                 /* Special case. Sending ::1 around between servers
 754                                  * and to clients is dangerous, because the : on the
 755                                  * start makes the client or server interpret the IP
 756                                  * as the last parameter on the line with a value ":1".
 757                                  */
 758                                 if (*formatted == ':')
 759                                         resultstr = "0" + resultstr;
 760                         }
 761                         break;
 762
 763                         case DNS_QUERY_CNAME:
 764                                 /* Identical handling to PTR */
 765
 766                         case DNS_QUERY_PTR:
 767                                 /* Reverse lookups just come back as char* */
 768                                 resultstr = std::string((const char*)data.first);
 769                         break;
 770
 771                         default:
 772                         break;
 773
 774                 }
 775
 776                 /* Build the reply with the id and hostname/ip in it */
 777                 std::string ro = req->orig;
 778                 delete req;
 779                 return DNSResult(this_id,resultstr,ttl,ro);
 780         }
 781 }
 782
 783 /** A result is ready, process it */
 784 DNSInfo DNSRequest::ResultIsReady(DNSHeader &header, int length)
 785 {
 786         int i = 0;
 787         int q = 0;
 788         int curanswer, o;
 789         ResourceRecord rr;
 790         unsigned short ptr;
 791
 792         /* This is just to keep _FORTIFY_SOURCE happy */
 793         rr.type = DNS_QUERY_NONE;
 794         rr.rdlength = 0;
 795         rr.ttl = 1;     /* GCC is a whiney bastard -- see the XXX below. */
 796
 797         if (!(header.flags1 & FLAGS_MASK_QR))
 798                 return std::make_pair((unsigned char*)NULL,"Not a query result");
 799
 800         if (header.flags1 & FLAGS_MASK_OPCODE)
 801                 return std::make_pair((unsigned char*)NULL,"Unexpected value in DNS reply packet");
 802
 803         if (header.flags2 & FLAGS_MASK_RCODE)
 804                 return std::make_pair((unsigned char*)NULL,"Domain name not found");
 805
 806         if (header.ancount < 1)
 807                 return std::make_pair((unsigned char*)NULL,"No resource records returned");
 808
 809         /* Subtract the length of the header from the length of the packet */
 810         length -= 12;
 811
 812         while ((unsigned int)q < header.qdcount && i < length)
 813         {
 814                 if (header.payload[i] > 63)
 815                 {
 816                         i += 6;
 817                         q++;
 818                 }
 819                 else
 820                 {
 821                         if (header.payload[i] == 0)
 822                         {
 823                                 q++;
 824                                 i += 5;
 825                         }
 826                         else i += header.payload[i] + 1;
 827                 }
 828         }
 829         curanswer = 0;
 830         while ((unsigned)curanswer < header.ancount)
 831         {
 832                 q = 0;
 833                 while (q == 0 && i < length)
 834                 {
 835                         if (header.payload[i] > 63)
 836                         {
 837                                 i += 2;
 838                                 q = 1;
 839                         }
 840                         else
 841                         {
 842                                 if (header.payload[i] == 0)
 843                                 {
 844                                         i++;
 845                                         q = 1;
 846                                 }
 847                                 else i += header.payload[i] + 1; /* skip length and label */
 848                         }
 849                 }
 850                 if (length - i < 10)
 851                         return std::make_pair((unsigned char*)NULL,"Incorrectly sized DNS reply");
 852
 853                 /* XXX: We actually initialise 'rr' here including its ttl field */
 854                 DNS::FillResourceRecord(&rr,&header.payload[i]);
 855                 i += 10;
 856                 if (rr.type != this->type)
 857                 {
 858                         curanswer++;
 859                         i += rr.rdlength;
 860                         continue;
 861                 }
 862                 if (rr.rr_class != this->rr_class)
 863                 {
 864                         curanswer++;
 865                         i += rr.rdlength;
 866                         continue;
 867                 }
 868                 break;
 869         }
 870         if ((unsigned int)curanswer == header.ancount)
 871                 return std::make_pair((unsigned char*)NULL,"No valid answers");
 872
 873         if (i + rr.rdlength > (unsigned int)length)
 874                 return std::make_pair((unsigned char*)NULL,"Resource record larger than stated");
 875
 876         if (rr.rdlength > 1023)
 877                 return std::make_pair((unsigned char*)NULL,"Resource record too large");
 878
 879         this->ttl = rr.ttl;
 880
 881         switch (rr.type)
 882         {
 883                 case DNS_QUERY_CNAME:
 884                         /* CNAME and PTR have the same processing code */
 885                 case DNS_QUERY_PTR:
 886                         o = 0;
 887                         q = 0;
 888                         while (q == 0 && i < length && o + 256 < 1023)
 889                         {
 890                                 if (header.payload[i] > 63)
 891                                 {
 892                                         memcpy(&ptr,&header.payload[i],2);
 893                                         i = ntohs(ptr) - 0xC000 - 12;
 894                                 }
 895                                 else
 896                                 {
 897                                         if (header.payload[i] == 0)
 898                                         {
 899                                                 q = 1;
 900                                         }
 901                                         else
 902                                         {
 903                                                 res[o] = 0;
 904                                                 if (o != 0)
 905                                                         res[o++] = '.';
 906                                                 memcpy(&res[o],&header.payload[i + 1],header.payload[i]);
 907                                                 o += header.payload[i];
 908                                                 i += header.payload[i] + 1;
 909                                         }
 910                                 }
 911                         }
 912                         res[o] = 0;
 913                 break;
 914                 case DNS_QUERY_AAAA:
 915                         memcpy(res,&header.payload[i],rr.rdlength);
 916                         res[rr.rdlength] = 0;
 917                 break;
 918                 case DNS_QUERY_A:
 919                         memcpy(res,&header.payload[i],rr.rdlength);
 920                         res[rr.rdlength] = 0;
 921                 break;
 922                 default:
 923                         memcpy(res,&header.payload[i],rr.rdlength);
 924                         res[rr.rdlength] = 0;
 925                 break;
 926         }
 927         return std::make_pair(res,"No error");;
 928 }
 929
 930 /** Close the master socket */
 931 DNS::~DNS()
 932 {
 933         shutdown(this->GetFd(), 2);
 934         close(this->GetFd());
 935         ServerInstance->Timers->DelTimer(this->PruneTimer);
 936         delete this->PruneTimer;
 937 }
 938
 939 CachedQuery* DNS::GetCache(const std::string &source)
 940 {
 941         dnscache::iterator x = cache->find(source.c_str());
 942         if (x != cache->end())
 943                 return &(x->second);
 944         else
 945                 return NULL;
 946 }
 947
 948 void DNS::DelCache(const std::string &source)
 949 {
 950         cache->erase(source.c_str());
 951 }
 952
 953 void Resolver::TriggerCachedResult()
 954 {
 955         if (CQ)
 956                 OnLookupComplete(CQ->data, time_left, true);
 957 }
 958
 959 /** High level abstraction of dns used by application at large */
 960 Resolver::Resolver(InspIRCd* Instance, const std::string &source, QueryType qt, bool &cached, Module* creator) : ServerInstance(Instance), Creator(creator), input(source), querytype(qt)
 961 {
 962         cached = false;
 963
 964         CQ = ServerInstance->Res->GetCache(source);
 965         if (CQ)
 966         {
 967                 time_left = CQ->CalcTTLRemaining();
 968                 if (!time_left)
 969                 {
 970                         ServerInstance->Res->DelCache(source);
 971                 }
 972                 else
 973                 {
 974                         cached = true;
 975                         return;
 976                 }
 977         }
 978
 979         insp_inaddr binip;
 980
 981         switch (querytype)
 982         {
 983                 case DNS_QUERY_A:
 984                         this->myid = ServerInstance->Res->GetIP(source.c_str());
 985                 break;
 986
 987                 case DNS_QUERY_PTR:
 988                         if (insp_aton(source.c_str(), &binip) > 0)
 989                         {
 990                                 /* Valid ip address */
 991                                 this->myid = ServerInstance->Res->GetName(&binip);
 992                         }
 993                         else
 994                         {
 995                                 this->OnError(RESOLVER_BADIP, "Bad IP address for reverse lookup");
 996                                 throw ModuleException("Resolver: Bad IP address");
 997                                 return;
 998                         }
 999                 break;
1000
1001                 case DNS_QUERY_PTR4:
1002                         querytype = DNS_QUERY_PTR;
1003                         this->myid = ServerInstance->Res->GetNameForce(source.c_str(), PROTOCOL_IPV4);
1004                 break;
1005
1006                 case DNS_QUERY_PTR6:
1007                         querytype = DNS_QUERY_PTR;
1008                         this->myid = ServerInstance->Res->GetNameForce(source.c_str(), PROTOCOL_IPV6);
1009                 break;
1010
1011                 case DNS_QUERY_AAAA:
1012                         this->myid = ServerInstance->Res->GetIP6(source.c_str());
1013                 break;
1014
1015                 case DNS_QUERY_CNAME:
1016                         this->myid = ServerInstance->Res->GetCName(source.c_str());
1017                 break;
1018
1019                 default:
1020                         this->myid = -1;
1021                 break;
1022         }
1023         if (this->myid == -1)
1024         {
1025                 this->OnError(RESOLVER_NSDOWN, "Nameserver is down");
1026                 throw ModuleException("Resolver: Couldnt get an id to make a request");
1027                 /* We shouldnt get here really */
1028                 return;
1029         }
1030 }
1031
1032 /** Called when an error occurs */
1033 void Resolver::OnError(ResolverError e, const std::string &errormessage)
1034 {
1035         /* Nothing in here */
1036 }
1037
1038 /** Destroy a resolver */
1039 Resolver::~Resolver()
1040 {
1041         /* Nothing here (yet) either */
1042 }
1043
1044 /** Get the request id associated with this class */
1045 int Resolver::GetId()
1046 {
1047         return this->myid;
1048 }
1049
1050 Module* Resolver::GetCreator()
1051 {
1052         return this->Creator;
1053 }
1054
1055 /** Process a socket read event */
1056 void DNS::HandleEvent(EventType et, int errornum)
1057 {
1058         /* Fetch the id and result of the next available packet */
1059         DNSResult res = this->GetResult();
1060         /* Is there a usable request id? */
1061         if (res.id != -1)
1062         {
1063                 /* Its an error reply */
1064                 if (res.id & ERROR_MASK)
1065                 {
1066                         /* Mask off the error bit */
1067                         res.id -= ERROR_MASK;
1068                         /* Marshall the error to the correct class */
1069                         if (Classes[res.id])
1070                         {
1071                                 if (ServerInstance && ServerInstance->stats)
1072                                         ServerInstance->stats->statsDnsBad++;
1073                                 Classes[res.id]->OnError(RESOLVER_NXDOMAIN, res.result);
1074                                 delete Classes[res.id];
1075                                 Classes[res.id] = NULL;
1076                         }
1077                 }
1078                 else
1079                 {
1080                         /* It is a non-error result, marshall the result to the correct class */
1081                         if (Classes[res.id])
1082                         {
1083                                 if (ServerInstance && ServerInstance->stats)
1084                                         ServerInstance->stats->statsDnsGood++;
1085
1086                                 if (!this->GetCache(res.original.c_str()))
1087                                         this->cache->insert(std::make_pair(res.original.c_str(), CachedQuery(res.result, res.ttl)));
1088
1089                                 Classes[res.id]->OnLookupComplete(res.result, res.ttl, false);
1090                                 delete Classes[res.id];
1091                                 Classes[res.id] = NULL;
1092                         }
1093                 }
1094
1095                 if (ServerInstance && ServerInstance->stats)
1096                         ServerInstance->stats->statsDns++;
1097         }
1098 }
1099
1100 /** Add a derived Resolver to the working set */
1101 bool DNS::AddResolverClass(Resolver* r)
1102 {
1103         /* Check the pointers validity and the id's validity */
1104         if ((r) && (r->GetId() > -1))
1105         {
1106                 /* Check the slot isnt already occupied -
1107                  * This should NEVER happen unless we have
1108                  * a severely broken DNS server somewhere
1109                  */
1110                 if (!Classes[r->GetId()])
1111                 {
1112                         /* Set up the pointer to the class */
1113                         Classes[r->GetId()] = r;
1114                         return true;
1115                 }
1116                 else
1117                         /* Duplicate id */
1118                         return false;
1119         }
1120         else
1121         {
1122                 /* Pointer or id not valid.
1123                  * Free the item and return
1124                  */
1125                 if (r)
1126                         delete r;
1127
1128                 return false;
1129         }
1130 }
1131
1132 void DNS::CleanResolvers(Module* module)
1133 {
1134         for (int i = 0; i < MAX_REQUEST_ID; i++)
1135         {
1136                 if (Classes[i])
1137                 {
1138                         if (Classes[i]->GetCreator() == module)
1139                         {
1140                                 Classes[i]->OnError(RESLOVER_FORCEUNLOAD, "Parent module is unloading");
1141                                 delete Classes[i];
1142                                 Classes[i] = NULL;
1143                         }
1144                 }
1145         }
1146 }
1147
1148 /** Generate pseudo-random number */
1149 unsigned long DNS::PRNG()
1150 {
1151 #ifndef WIN32
1152         unsigned long val = 0;
1153         timeval n;
1154         serverstats* s = ServerInstance->stats;
1155         gettimeofday(&n,NULL);
1156         val = (n.tv_usec ^ getpid() ^ geteuid() ^ (this->currid++)) ^ s->statsAccept + n.tv_sec;
1157         val = val + s->statsCollisions ^ s->statsDnsGood - s->statsDnsBad;
1158         val += (s->statsConnects ^ (unsigned long)s->statsSent ^ (unsigned long)s->statsRecv) - ServerInstance->Config->ports.size();
1159         return val;
1160 #else
1161         unsigned long val = 0;
1162         serverstats* s = ServerInstance->stats;
1163         val = (time(NULL) ^ GetCurrentProcessId() ^ GetCurrentThreadId() ^ (this->currid++)) ^ s->statsAccept + time(NULL);
1164         val = val + s->statsCollisions ^ s->statsDnsGood - s->statsDnsBad;
1165         val += (s->statsConnects ^ (unsigned long)s->statsSent ^ (unsigned long)s->statsRecv);
1166         return val;
1167 #endif
1168 }
1169