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 #include "inspircd_se_config.h"
  33 #endif
  34
  35 #include "dns.h"
  36 #include "inspircd.h"
  37 #include "socketengine.h"
  38 #include "configreader.h"
  39 #include "socket.h"
  40
  41 using irc::sockets::insp_inaddr;
  42 using irc::sockets::insp_ntoa;
  43 using irc::sockets::insp_aton;
  44 using irc::sockets::OpenTCPSocket;
  45
  46 /** Masks to mask off the responses we get from the DNSRequest methods
  47  */
  48 enum QueryInfo
  49 {
  50         ERROR_MASK      = 0x10000       /* Result is an error */
  51 };
  52
  53 /** Flags which can be ORed into a request or reply for different meanings
  54  */
  55 enum QueryFlags
  56 {
  57         FLAGS_MASK_RD           = 0x01, /* Recursive */
  58         FLAGS_MASK_TC           = 0x02,
  59         FLAGS_MASK_AA           = 0x04, /* Authoritative */
  60         FLAGS_MASK_OPCODE       = 0x78,
  61         FLAGS_MASK_QR           = 0x80,
  62         FLAGS_MASK_RCODE        = 0x0F, /* Request */
  63         FLAGS_MASK_Z            = 0x70,
  64         FLAGS_MASK_RA           = 0x80
  65 };
  66
  67
  68 /** Represents a dns resource record (rr)
  69  */
  70 struct ResourceRecord
  71 {
  72         QueryType       type;           /* Record type */
  73         unsigned int    rr_class;       /* Record class */
  74         unsigned long   ttl;            /* Time to live */
  75         unsigned int    rdlength;       /* Record length */
  76 };
  77
  78 /** Represents a dns request/reply header, and its payload as opaque data.
  79  */
  80 class DNSHeader
  81 {
  82  public:
  83         unsigned char   id[2];          /* Request id */
  84         unsigned int    flags1;         /* Flags */
  85         unsigned int    flags2;         /* Flags */
  86         unsigned int    qdcount;
  87         unsigned int    ancount;        /* Answer count */
  88         unsigned int    nscount;        /* Nameserver count */
  89         unsigned int    arcount;
  90         unsigned char   payload[512];   /* Packet payload */
  91 };
  92
  93 class DNSRequest
  94 {
  95  public:
  96         unsigned char   id[2];          /* Request id */
  97         unsigned char*  res;            /* Result processing buffer */
  98         unsigned int    rr_class;       /* Request class */
  99         QueryType       type;           /* Request type */
 100         DNS*            dnsobj;         /* DNS caller (where we get our FD from) */
 101         unsigned long   ttl;            /* Time to live */
 102         std::string     orig;           /* Original requested name/ip */
 103
 104         DNSRequest(InspIRCd* Instance, DNS* dns, int id, const std::string &original);
 105         ~DNSRequest();
 106         DNSInfo ResultIsReady(DNSHeader &h, int length);
 107         int SendRequests(const DNSHeader *header, const int length, QueryType qt);
 108 };
 109
 110 class CacheTimer : public InspTimer
 111 {
 112  private:
 113         InspIRCd* ServerInstance;
 114         DNS* dns;
 115  public:
 116         CacheTimer(InspIRCd* Instance, DNS* thisdns)
 117                 : InspTimer(3600, Instance->Time(), true), ServerInstance(Instance), dns(thisdns) { }
 118
 119         virtual void Tick(time_t TIME)
 120         {
 121                 dns->PruneCache();
 122         }
 123 };
 124
 125 class RequestTimeout : public InspTimer
 126 {
 127         InspIRCd* ServerInstance;
 128         DNSRequest* watch;
 129         int watchid;
 130  public:
 131         RequestTimeout(unsigned long n, InspIRCd* SI, DNSRequest* watching, int id) : InspTimer(n, time(NULL)), ServerInstance(SI), watch(watching), watchid(id)
 132         {
 133         }
 134
 135         void Tick(time_t TIME)
 136         {
 137                 if (ServerInstance->Res->requests[watchid] == watch)
 138                 {
 139                         /* Still exists, whack it */
 140                         if (ServerInstance->Res->Classes[watchid])
 141                         {
 142                                 ServerInstance->Res->Classes[watchid]->OnError(RESOLVER_TIMEOUT, "Request timed out");
 143                                 delete ServerInstance->Res->Classes[watchid];
 144                                 ServerInstance->Res->Classes[watchid] = NULL;
 145                         }
 146                         ServerInstance->Res->requests[watchid] = NULL;
 147                         DELETE(watch);
 148                         return;
 149                 }
 150         }
 151 };
 152
 153 /* Allocate the processing buffer */
 154 DNSRequest::DNSRequest(InspIRCd* Instance, DNS* dns, int id, const std::string &original) : dnsobj(dns)
 155 {
 156         res = new unsigned char[512];
 157         *res = 0;
 158         orig = original;
 159         RequestTimeout* RT = new RequestTimeout(Instance->Config->dns_timeout ? Instance->Config->dns_timeout : 5, Instance, this, id);
 160         Instance->Timers->AddTimer(RT); /* The timer manager frees this */
 161 }
 162
 163 /* Deallocate the processing buffer */
 164 DNSRequest::~DNSRequest()
 165 {
 166         delete[] res;
 167 }
 168
 169 /** Fill a ResourceRecord class based on raw data input */
 170 inline void DNS::FillResourceRecord(ResourceRecord* rr, const unsigned char *input)
 171 {
 172         rr->type = (QueryType)((input[0] << 8) + input[1]);
 173         rr->rr_class = (input[2] << 8) + input[3];
 174         rr->ttl = (input[4] << 24) + (input[5] << 16) + (input[6] << 8) + input[7];
 175         rr->rdlength = (input[8] << 8) + input[9];
 176 }
 177
 178 /** Fill a DNSHeader class based on raw data input of a given length */
 179 inline void DNS::FillHeader(DNSHeader *header, const unsigned char *input, const int length)
 180 {
 181         header->id[0] = input[0];
 182         header->id[1] = input[1];
 183         header->flags1 = input[2];
 184         header->flags2 = input[3];
 185         header->qdcount = (input[4] << 8) + input[5];
 186         header->ancount = (input[6] << 8) + input[7];
 187         header->nscount = (input[8] << 8) + input[9];
 188         header->arcount = (input[10] << 8) + input[11];
 189         memcpy(header->payload,&input[12],length);
 190 }
 191
 192 /** Empty a DNSHeader class out into raw data, ready for transmission */
 193 inline void DNS::EmptyHeader(unsigned char *output, const DNSHeader *header, const int length)
 194 {
 195         output[0] = header->id[0];
 196         output[1] = header->id[1];
 197         output[2] = header->flags1;
 198         output[3] = header->flags2;
 199         output[4] = header->qdcount >> 8;
 200         output[5] = header->qdcount & 0xFF;
 201         output[6] = header->ancount >> 8;
 202         output[7] = header->ancount & 0xFF;
 203         output[8] = header->nscount >> 8;
 204         output[9] = header->nscount & 0xFF;
 205         output[10] = header->arcount >> 8;
 206         output[11] = header->arcount & 0xFF;
 207         memcpy(&output[12],header->payload,length);
 208 }
 209
 210 /** Send requests we have previously built down the UDP socket */
 211 int DNSRequest::SendRequests(const DNSHeader *header, const int length, QueryType qt)
 212 {
 213         unsigned char payload[sizeof(DNSHeader)];
 214
 215         this->rr_class = 1;
 216         this->type = qt;
 217
 218         DNS::EmptyHeader(payload,header,length);
 219
 220 #ifdef IPV6
 221         if (this->dnsobj->socketfamily == AF_INET6)
 222         {
 223                 sockaddr_in6 addr;
 224                 memset(&addr,0,sizeof(addr));
 225                 memcpy(&addr.sin6_addr,&dnsobj->myserver6,sizeof(addr.sin6_addr));
 226                 addr.sin6_family = AF_INET6;
 227                 addr.sin6_port = htons(DNS::QUERY_PORT);
 228                 if (sendto(dnsobj->GetFd(), payload, length + 12, 0, (sockaddr *) &addr, sizeof(addr)) != length+12)
 229                         return -1;
 230         }
 231         else
 232         {
 233                 sockaddr_in addr;
 234                 memset(&addr,0,sizeof(addr));
 235                 memcpy(&addr.sin_addr.s_addr,&dnsobj->myserver4,sizeof(addr.sin_addr));
 236                 addr.sin_family = AF_INET;
 237                 addr.sin_port = htons(DNS::QUERY_PORT);
 238                 if (sendto(dnsobj->GetFd(), payload, length + 12, 0, (sockaddr *) &addr, sizeof(addr)) != length+12)
 239                         return -1;
 240         }
 241 #else
 242         sockaddr_in addr;
 243         memset(&addr,0,sizeof(addr));
 244         memcpy(&addr.sin_addr.s_addr, &dnsobj->myserver4, sizeof(addr.sin_addr));
 245         addr.sin_family = AF_INET;
 246         addr.sin_port = htons(DNS::QUERY_PORT);
 247         if (sendto(dnsobj->GetFd(), (const char*)payload, length + 12, 0, (sockaddr *) &addr, sizeof(addr)) != length+12)
 248                 return -1;
 249 #endif
 250
 251         return 0;
 252 }
 253
 254 /** Add a query with a predefined header, and allocate an ID for it. */
 255 DNSRequest* DNS::AddQuery(DNSHeader *header, int &id, const char* original)
 256 {
 257         /* Is the DNS connection down? */
 258         if (this->GetFd() == -1)
 259                 return NULL;
 260
 261         /* Create an id */
 262         id = this->PRNG() & DNS::MAX_REQUEST_ID;
 263
 264         /* If this id is already 'in flight', pick another. */
 265         while (requests[id])
 266                 id = this->PRNG() & DNS::MAX_REQUEST_ID;
 267
 268         DNSRequest* req = new DNSRequest(ServerInstance, this, id, original);
 269
 270         header->id[0] = req->id[0] = id >> 8;
 271         header->id[1] = req->id[1] = id & 0xFF;
 272         header->flags1 = FLAGS_MASK_RD;
 273         header->flags2 = 0;
 274         header->qdcount = 1;
 275         header->ancount = 0;
 276         header->nscount = 0;
 277         header->arcount = 0;
 278
 279         /* At this point we already know the id doesnt exist,
 280          * so there needs to be no second check for the ::end()
 281          */
 282         requests[id] = req;
 283
 284         /* According to the C++ spec, new never returns NULL. */
 285         return req;
 286 }
 287
 288 int DNS::ClearCache()
 289 {
 290         /* This ensures the buckets are reset to sane levels */
 291         int rv = this->cache->size();
 292         delete this->cache;
 293         this->cache = new dnscache();
 294         return rv;
 295 }
 296
 297 int DNS::PruneCache()
 298 {
 299         int n = 0;
 300         dnscache* newcache = new dnscache();
 301         for (dnscache::iterator i = this->cache->begin(); i != this->cache->end(); i++)
 302                 /* Dont include expired items (theres no point) */
 303                 if (i->second.CalcTTLRemaining())
 304                         newcache->insert(*i);
 305                 else
 306                         n++;
 307
 308         delete this->cache;
 309         this->cache = newcache;
 310         return n;
 311 }
 312
 313 void DNS::Rehash()
 314 {
 315         ip6munge = false;
 316         int portpass = 0;
 317
 318         if (this->GetFd() > -1)
 319         {
 320                 if (ServerInstance && ServerInstance->SE)
 321                         ServerInstance->SE->DelFd(this);
 322                 shutdown(this->GetFd(), 2);
 323                 close(this->GetFd());
 324                 this->SetFd(-1);
 325
 326                 /* Rehash the cache */
 327                 this->PruneCache();
 328         }
 329         else
 330         {
 331                 /* Create initial dns cache */
 332                 this->cache = new dnscache();
 333         }
 334
 335         if ((strstr(ServerInstance->Config->DNSServer,"::ffff:") == (char*)&ServerInstance->Config->DNSServer) ||  (strstr(ServerInstance->Config->DNSServer,"::FFFF:") == (char*)&ServerInstance->Config->DNSServer))
 336         {
 337                 ServerInstance->Log(DEFAULT,"WARNING: Using IPv4 addresses over IPv6 forces some DNS checks to be disabled.");
 338                 ServerInstance->Log(DEFAULT,"         This should not cause a problem, however it is recommended you migrate");
 339                 ServerInstance->Log(DEFAULT,"         to a true IPv6 environment.");
 340                 this->ip6munge = true;
 341         }
 342
 343         this->socketfamily = AF_INET;
 344 #ifdef IPV6
 345         if (strchr(ServerInstance->Config->DNSServer,':'))
 346         {
 347                 this->socketfamily = AF_INET6;
 348                 inet_pton(AF_INET6, ServerInstance->Config->DNSServer, &this->myserver6);
 349         }
 350         else
 351         {
 352                 inet_aton(ServerInstance->Config->DNSServer, &this->myserver4);
 353                 portpass = -1;
 354         }
 355 #else
 356         inet_aton(ServerInstance->Config->DNSServer, &this->myserver4);
 357 #endif
 358
 359         /* Initialize mastersocket */
 360         int s = OpenTCPSocket(ServerInstance->Config->DNSServer, SOCK_DGRAM);
 361         this->SetFd(s);
 362
 363         /* Have we got a socket and is it nonblocking? */
 364         if (this->GetFd() != -1)
 365         {
 366                 /* Bind the port - port 0 INADDR_ANY */
 367                 if (!ServerInstance->BindSocket(this->GetFd(), portpass, "", false))
 368                 {
 369                         /* Failed to bind */
 370                         shutdown(this->GetFd(),2);
 371                         close(this->GetFd());
 372                         this->SetFd(-1);
 373                 }
 374
 375                 if (this->GetFd() >= 0)
 376                 {
 377                         /* Hook the descriptor into the socket engine */
 378                         if (ServerInstance && ServerInstance->SE)
 379                         {
 380                                 if (!ServerInstance->SE->AddFd(this))
 381                                 {
 382                                         ServerInstance->Log(DEFAULT,"Internal error starting DNS - hostnames will NOT resolve.");
 383                                         shutdown(this->GetFd(),2);
 384                                         close(this->GetFd());
 385                                         this->SetFd(-1);
 386                                 }
 387                         }
 388                 }
 389         }
 390 }
 391
 392 /** Initialise the DNS UDP socket so that we can send requests */
 393 DNS::DNS(InspIRCd* Instance) : ServerInstance(Instance)
 394 {
 395         /* Clear the Resolver class table */
 396         memset(Classes,0,sizeof(Classes));
 397
 398         /* Clear the requests class table */
 399         memset(requests,0,sizeof(requests));
 400
 401         /* Set the id of the next request to 0
 402          */
 403         currid = 0;
 404
 405         /* DNS::Rehash() sets this to a valid ptr
 406          */
 407         this->cache = NULL;
 408
 409         /* Again, DNS::Rehash() sets this to a
 410          * valid value
 411          */
 412         this->SetFd(-1);
 413
 414         /* Actually read the settings
 415          */
 416         this->Rehash();
 417
 418         this->PruneTimer = new CacheTimer(ServerInstance, this);
 419
 420         ServerInstance->Timers->AddTimer(this->PruneTimer);
 421 }
 422
 423 /** Build a payload to be placed after the header, based upon input data, a resource type, a class and a pointer to a buffer */
 424 int DNS::MakePayload(const char * const name, const QueryType rr, const unsigned short rr_class, unsigned char * const payload)
 425 {
 426         short payloadpos = 0;
 427         const char* tempchr, *tempchr2 = name;
 428         unsigned short length;
 429
 430         /* split name up into labels, create query */
 431         while ((tempchr = strchr(tempchr2,'.')) != NULL)
 432         {
 433                 length = tempchr - tempchr2;
 434                 if (payloadpos + length + 1 > 507)
 435                         return -1;
 436                 payload[payloadpos++] = length;
 437                 memcpy(&payload[payloadpos],tempchr2,length);
 438                 payloadpos += length;
 439                 tempchr2 = &tempchr[1];
 440         }
 441         length = strlen(tempchr2);
 442         if (length)
 443         {
 444                 if (payloadpos + length + 2 > 507)
 445                         return -1;
 446                 payload[payloadpos++] = length;
 447                 memcpy(&payload[payloadpos],tempchr2,length);
 448                 payloadpos += length;
 449                 payload[payloadpos++] = 0;
 450         }
 451         if (payloadpos > 508)
 452                 return -1;
 453         length = htons(rr);
 454         memcpy(&payload[payloadpos],&length,2);
 455         length = htons(rr_class);
 456         memcpy(&payload[payloadpos + 2],&length,2);
 457         return payloadpos + 4;
 458 }
 459
 460 /** Start lookup of an hostname to an IP address */
 461 int DNS::GetIP(const char *name)
 462 {
 463         DNSHeader h;
 464         int id;
 465         int length;
 466
 467         if ((length = this->MakePayload(name, DNS_QUERY_A, 1, (unsigned char*)&h.payload)) == -1)
 468                 return -1;
 469
 470         DNSRequest* req = this->AddQuery(&h, id, name);
 471
 472         if ((!req) || (req->SendRequests(&h, length, DNS_QUERY_A) == -1))
 473                 return -1;
 474
 475         return id;
 476 }
 477
 478 /** Start lookup of an hostname to an IPv6 address */
 479 int DNS::GetIP6(const char *name)
 480 {
 481         DNSHeader h;
 482         int id;
 483         int length;
 484
 485         if ((length = this->MakePayload(name, DNS_QUERY_AAAA, 1, (unsigned char*)&h.payload)) == -1)
 486                 return -1;
 487
 488         DNSRequest* req = this->AddQuery(&h, id, name);
 489
 490         if ((!req) || (req->SendRequests(&h, length, DNS_QUERY_AAAA) == -1))
 491                 return -1;
 492
 493         return id;
 494 }
 495
 496 /** Start lookup of a cname to another name */
 497 int DNS::GetCName(const char *alias)
 498 {
 499         DNSHeader h;
 500         int id;
 501         int length;
 502
 503         if ((length = this->MakePayload(alias, DNS_QUERY_CNAME, 1, (unsigned char*)&h.payload)) == -1)
 504                 return -1;
 505
 506         DNSRequest* req = this->AddQuery(&h, id, alias);
 507
 508         if ((!req) || (req->SendRequests(&h, length, DNS_QUERY_CNAME) == -1))
 509                 return -1;
 510
 511         return id;
 512 }
 513
 514 /** Start lookup of an IP address to a hostname */
 515 int DNS::GetName(const insp_inaddr *ip)
 516 {
 517         char query[128];
 518         DNSHeader h;
 519         int id;
 520         int length;
 521
 522 #ifdef IPV6
 523         unsigned char* c = (unsigned char*)&ip->s6_addr;
 524         if (c[0] == 0 && c[1] == 0 && c[2] == 0 && c[3] == 0 &&
 525             c[4] == 0 && c[5] == 0 && c[6] == 0 && c[7] == 0 &&
 526             c[8] == 0 && c[9] == 0 && c[10] == 0xFF && c[11] == 0xFF)
 527                 sprintf(query,"%d.%d.%d.%d.in-addr.arpa",c[15],c[14],c[13],c[12]);
 528         else
 529                 DNS::MakeIP6Int(query, (in6_addr*)ip);
 530 #else
 531         unsigned char* c = (unsigned char*)&ip->s_addr;
 532         sprintf(query,"%d.%d.%d.%d.in-addr.arpa",c[3],c[2],c[1],c[0]);
 533 #endif
 534
 535         if ((length = this->MakePayload(query, DNS_QUERY_PTR, 1, (unsigned char*)&h.payload)) == -1)
 536                 return -1;
 537
 538         DNSRequest* req = this->AddQuery(&h, id, insp_ntoa(*ip));
 539
 540         if ((!req) || (req->SendRequests(&h, length, DNS_QUERY_PTR) == -1))
 541                 return -1;
 542
 543         return id;
 544 }
 545
 546 /** Start lookup of an IP address to a hostname */
 547 int DNS::GetNameForce(const char *ip, ForceProtocol fp)
 548 {
 549         char query[128];
 550         DNSHeader h;
 551         int id;
 552         int length;
 553 #ifdef SUPPORT_IP6LINKS
 554         if (fp == PROTOCOL_IPV6)
 555         {
 556                 in6_addr i;
 557                 if (inet_pton(AF_INET6, ip, &i) > 0)
 558                 {
 559                         DNS::MakeIP6Int(query, &i);
 560                 }
 561                 else
 562                         /* Invalid IP address */
 563                         return -1;
 564         }
 565         else
 566 #endif
 567         {
 568                 in_addr i;
 569                 if (inet_aton(ip, &i))
 570                 {
 571                         unsigned char* c = (unsigned char*)&i.s_addr;
 572                         sprintf(query,"%d.%d.%d.%d.in-addr.arpa",c[3],c[2],c[1],c[0]);
 573                 }
 574                 else
 575                         /* Invalid IP address */
 576                         return -1;
 577         }
 578
 579         if ((length = this->MakePayload(query, DNS_QUERY_PTR, 1, (unsigned char*)&h.payload)) == -1)
 580                 return -1;
 581
 582         DNSRequest* req = this->AddQuery(&h, id, ip);
 583
 584         if ((!req) || (req->SendRequests(&h, length, DNS_QUERY_PTR) == -1))
 585                 return -1;
 586
 587         return id;
 588 }
 589
 590 /** Build an ipv6 reverse domain from an in6_addr
 591  */
 592 void DNS::MakeIP6Int(char* query, const in6_addr *ip)
 593 {
 594 #ifdef SUPPORT_IP6LINKS
 595         const char* hex = "0123456789abcdef";
 596         for (int index = 31; index >= 0; index--) /* for() loop steps twice per byte */
 597         {
 598                 if (index % 2)
 599                         /* low nibble */
 600                         *query++ = hex[ip->s6_addr[index / 2] & 0x0F];
 601                 else
 602                         /* high nibble */
 603                         *query++ = hex[(ip->s6_addr[index / 2] & 0xF0) >> 4];
 604                 *query++ = '.'; /* Seperator */
 605         }
 606         strcpy(query,"ip6.arpa"); /* Suffix the string */
 607 #else
 608         *query = 0;
 609 #endif
 610 }
 611
 612 /** Return the next id which is ready, and the result attached to it */
 613 DNSResult DNS::GetResult()
 614 {
 615         /* Fetch dns query response and decide where it belongs */
 616         DNSHeader header;
 617         DNSRequest *req;
 618         unsigned char buffer[sizeof(DNSHeader)];
 619         sockaddr* from = new sockaddr[2];
 620 #ifdef IPV6
 621         socklen_t x = this->socketfamily == AF_INET ? sizeof(sockaddr_in) : sizeof(sockaddr_in6);
 622 #else
 623         socklen_t x = sizeof(sockaddr_in);
 624 #endif
 625         const char* ipaddr_from;
 626         unsigned short int port_from = 0;
 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.insert(0, "0");
 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