2 * InspIRCd -- Internet Relay Chat Daemon
4 * Copyright (C) 2013 Adam <Adam@anope.org>
5 * Copyright (C) 2003-2013 Anope Team <team@anope.org>
7 * This file is part of InspIRCd. InspIRCd is free software: you can
8 * redistribute it and/or modify it under the terms of the GNU General Public
9 * License as published by the Free Software Foundation, version 2.
11 * This program is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
13 * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
16 * You should have received a copy of the GNU General Public License
17 * along with this program. If not, see <http://www.gnu.org/licenses/>.
21 #include "modules/dns.h"
27 #pragma comment(lib, "Iphlpapi.lib")
32 /** Maximum value of a dns request id, 16 bits wide, 0xFFFF.
34 const unsigned int MAX_REQUEST_ID = 0xFFFF;
39 /** A full packet sent or recieved to/from the nameserver
41 class Packet : public Query
43 static bool IsValidName(const std::string& name)
45 return (name.find_first_not_of("0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ.-") == std::string::npos);
48 void PackName(unsigned char* output, unsigned short output_size, unsigned short& pos, const std::string& name)
50 if (pos + name.length() + 2 > output_size)
51 throw Exception("Unable to pack name");
53 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Packing name " + name);
55 irc::sepstream sep(name, '.');
58 while (sep.GetToken(token))
60 output[pos++] = token.length();
61 memcpy(&output[pos], token.data(), token.length());
62 pos += token.length();
68 std::string UnpackName(const unsigned char* input, unsigned short input_size, unsigned short& pos)
71 unsigned short pos_ptr = pos, lowest_ptr = input_size;
72 bool compressed = false;
74 if (pos_ptr >= input_size)
75 throw Exception("Unable to unpack name - no input");
77 while (input[pos_ptr] > 0)
79 unsigned short offset = input[pos_ptr];
83 if ((offset & POINTER) != POINTER)
84 throw Exception("Unable to unpack name - bogus compression header");
85 if (pos_ptr + 1 >= input_size)
86 throw Exception("Unable to unpack name - bogus compression header");
88 /* Place pos at the second byte of the first (farthest) compression pointer */
89 if (compressed == false)
95 pos_ptr = (offset & LABEL) << 8 | input[pos_ptr + 1];
97 /* Pointers can only go back */
98 if (pos_ptr >= lowest_ptr)
99 throw Exception("Unable to unpack name - bogus compression pointer");
100 lowest_ptr = pos_ptr;
104 if (pos_ptr + offset + 1 >= input_size)
105 throw Exception("Unable to unpack name - offset too large");
108 for (unsigned i = 1; i <= offset; ++i)
109 name += input[pos_ptr + i];
111 pos_ptr += offset + 1;
112 if (compressed == false)
118 /* +1 pos either to one byte after the compression pointer or one byte after the ending \0 */
122 throw Exception("Unable to unpack name - no name");
124 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Unpack name " + name);
129 Question UnpackQuestion(const unsigned char* input, unsigned short input_size, unsigned short& pos)
133 q.name = this->UnpackName(input, input_size, pos);
135 if (pos + 4 > input_size)
136 throw Exception("Unable to unpack question");
138 q.type = static_cast<QueryType>(input[pos] << 8 | input[pos + 1]);
141 // Skip over query class code
147 ResourceRecord UnpackResourceRecord(const unsigned char* input, unsigned short input_size, unsigned short& pos)
149 ResourceRecord record = static_cast<ResourceRecord>(this->UnpackQuestion(input, input_size, pos));
151 if (pos + 6 > input_size)
152 throw Exception("Unable to unpack resource record");
154 record.ttl = (input[pos] << 24) | (input[pos + 1] << 16) | (input[pos + 2] << 8) | input[pos + 3];
157 uint16_t rdlength = input[pos] << 8 | input[pos + 1];
164 if (pos + 4 > input_size)
165 throw Exception("Unable to unpack resource record");
167 irc::sockets::sockaddrs addrs;
168 memset(&addrs, 0, sizeof(addrs));
170 addrs.in4.sin_family = AF_INET;
171 addrs.in4.sin_addr.s_addr = input[pos] | (input[pos + 1] << 8) | (input[pos + 2] << 16) | (input[pos + 3] << 24);
174 record.rdata = addrs.addr();
179 if (pos + 16 > input_size)
180 throw Exception("Unable to unpack resource record");
182 irc::sockets::sockaddrs addrs;
183 memset(&addrs, 0, sizeof(addrs));
185 addrs.in6.sin6_family = AF_INET6;
186 for (int j = 0; j < 16; ++j)
187 addrs.in6.sin6_addr.s6_addr[j] = input[pos + j];
190 record.rdata = addrs.addr();
197 record.rdata = this->UnpackName(input, input_size, pos);
198 if (!IsValidName(record.rdata))
199 throw Exception("Invalid name"); // XXX: Causes the request to time out
205 if (pos + rdlength > input_size)
206 throw Exception("Unable to unpack txt resource record");
208 record.rdata = std::string(reinterpret_cast<const char *>(input + pos), rdlength);
211 if (record.rdata.find_first_of("\r\n\0", 0, 3) != std::string::npos)
212 throw Exception("Invalid character in txt record");
220 if (!record.name.empty() && !record.rdata.empty())
221 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, record.name + " -> " + record.rdata);
227 static const int POINTER = 0xC0;
228 static const int LABEL = 0x3F;
229 static const int HEADER_LENGTH = 12;
231 /* ID for this packet */
233 /* Flags on the packet */
234 unsigned short flags;
236 Packet() : id(0), flags(0)
240 void Fill(const unsigned char* input, const unsigned short len)
242 if (len < HEADER_LENGTH)
243 throw Exception("Unable to fill packet");
245 unsigned short packet_pos = 0;
247 this->id = (input[packet_pos] << 8) | input[packet_pos + 1];
250 this->flags = (input[packet_pos] << 8) | input[packet_pos + 1];
253 unsigned short qdcount = (input[packet_pos] << 8) | input[packet_pos + 1];
256 unsigned short ancount = (input[packet_pos] << 8) | input[packet_pos + 1];
259 unsigned short nscount = (input[packet_pos] << 8) | input[packet_pos + 1];
262 unsigned short arcount = (input[packet_pos] << 8) | input[packet_pos + 1];
265 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "qdcount: " + ConvToStr(qdcount) + " ancount: " + ConvToStr(ancount) + " nscount: " + ConvToStr(nscount) + " arcount: " + ConvToStr(arcount));
268 throw Exception("Question count != 1 in incoming packet");
270 this->question = this->UnpackQuestion(input, len, packet_pos);
272 for (unsigned i = 0; i < ancount; ++i)
273 this->answers.push_back(this->UnpackResourceRecord(input, len, packet_pos));
276 unsigned short Pack(unsigned char* output, unsigned short output_size)
278 if (output_size < HEADER_LENGTH)
279 throw Exception("Unable to pack packet");
281 unsigned short pos = 0;
283 output[pos++] = this->id >> 8;
284 output[pos++] = this->id & 0xFF;
285 output[pos++] = this->flags >> 8;
286 output[pos++] = this->flags & 0xFF;
287 output[pos++] = 0; // Question count, high byte
288 output[pos++] = 1; // Question count, low byte
289 output[pos++] = 0; // Answer count, high byte
290 output[pos++] = 0; // Answer count, low byte
297 Question& q = this->question;
299 if (q.type == QUERY_PTR)
301 irc::sockets::sockaddrs ip;
302 irc::sockets::aptosa(q.name, 0, ip);
304 if (q.name.find(':') != std::string::npos)
306 static const char* const hex = "0123456789abcdef";
307 char reverse_ip[128];
308 unsigned reverse_ip_count = 0;
309 for (int j = 15; j >= 0; --j)
311 reverse_ip[reverse_ip_count++] = hex[ip.in6.sin6_addr.s6_addr[j] & 0xF];
312 reverse_ip[reverse_ip_count++] = '.';
313 reverse_ip[reverse_ip_count++] = hex[ip.in6.sin6_addr.s6_addr[j] >> 4];
314 reverse_ip[reverse_ip_count++] = '.';
316 reverse_ip[reverse_ip_count++] = 0;
319 q.name += "ip6.arpa";
323 unsigned long forward = ip.in4.sin_addr.s_addr;
324 ip.in4.sin_addr.s_addr = forward << 24 | (forward & 0xFF00) << 8 | (forward & 0xFF0000) >> 8 | forward >> 24;
326 q.name = ip.addr() + ".in-addr.arpa";
330 this->PackName(output, output_size, pos, q.name);
332 if (pos + 4 >= output_size)
333 throw Exception("Unable to pack packet");
335 short s = htons(q.type);
336 memcpy(&output[pos], &s, 2);
339 // Query class, always IN
348 class MyManager : public Manager, public Timer, public EventHandler
350 typedef TR1NS::unordered_map<Question, Query, Question::hash> cache_map;
353 irc::sockets::sockaddrs myserver;
356 /** Maximum number of entries in cache
358 static const unsigned int MAX_CACHE_SIZE = 1000;
360 static bool IsExpired(const Query& record, time_t now = ServerInstance->Time())
362 const ResourceRecord& req = record.answers[0];
363 return (req.created + static_cast<time_t>(req.ttl) < now);
366 /** Check the DNS cache to see if request can be handled by a cached result
367 * @return true if a cached result was found.
369 bool CheckCache(DNS::Request* req, const DNS::Question& question)
371 ServerInstance->Logs->Log(MODNAME, LOG_SPARSE, "cache: Checking cache for " + question.name);
373 cache_map::iterator it = this->cache.find(question);
374 if (it == this->cache.end())
377 Query& record = it->second;
378 if (IsExpired(record))
380 this->cache.erase(it);
384 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "cache: Using cached result for " + question.name);
385 record.cached = true;
386 req->OnLookupComplete(&record);
390 /** Add a record to the dns cache
391 * @param r The record
393 void AddCache(Query& r)
395 if (cache.size() >= MAX_CACHE_SIZE)
398 // Determine the lowest TTL value and use that as the TTL of the cache entry
399 unsigned int cachettl = UINT_MAX;
400 for (std::vector<ResourceRecord>::const_iterator i = r.answers.begin(); i != r.answers.end(); ++i)
402 const ResourceRecord& rr = *i;
403 if (rr.ttl < cachettl)
407 cachettl = std::min(cachettl, (unsigned int)5*60);
408 ResourceRecord& rr = r.answers.front();
409 // Set TTL to what we've determined to be the lowest
411 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "cache: added cache for " + rr.name + " -> " + rr.rdata + " ttl: " + ConvToStr(rr.ttl));
412 this->cache[r.question] = r;
416 DNS::Request* requests[MAX_REQUEST_ID+1];
418 MyManager(Module* c) : Manager(c), Timer(5*60, true)
421 for (unsigned int i = 0; i <= MAX_REQUEST_ID; ++i)
423 ServerInstance->Timers.AddTimer(this);
428 // Ensure Process() will fail for new requests
431 for (unsigned int i = 0; i <= MAX_REQUEST_ID; ++i)
433 DNS::Request* request = requests[i];
437 Query rr(request->question);
438 rr.error = ERROR_UNKNOWN;
439 request->OnError(&rr);
445 void Process(DNS::Request* req) CXX11_OVERRIDE
447 if ((unloading) || (req->creator->dying))
448 throw Exception("Module is being unloaded");
450 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Processing request to lookup " + req->question.name + " of type " + ConvToStr(req->question.type) + " to " + this->myserver.addr());
453 unsigned int tries = 0;
457 id = ServerInstance->GenRandomInt(DNS::MAX_REQUEST_ID+1);
459 if (++tries == DNS::MAX_REQUEST_ID*5)
461 // If we couldn't find an empty slot this many times, do a sequential scan as a last
462 // resort. If an empty slot is found that way, go on, otherwise throw an exception
464 for (unsigned int i = 0; i <= DNS::MAX_REQUEST_ID; i++)
466 if (!this->requests[i])
474 throw Exception("DNS: All ids are in use");
479 while (this->requests[id]);
482 this->requests[req->id] = req;
485 p.flags = QUERYFLAGS_RD;
487 p.question = req->question;
489 unsigned char buffer[524];
490 unsigned short len = p.Pack(buffer, sizeof(buffer));
492 /* Note that calling Pack() above can actually change the contents of p.question.name, if the query is a PTR,
493 * to contain the value that would be in the DNS cache, which is why this is here.
495 if (req->use_cache && this->CheckCache(req, p.question))
497 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Using cached result");
502 // Update name in the original request so question checking works for PTR queries
503 req->question.name = p.question.name;
505 if (SocketEngine::SendTo(this, buffer, len, 0, &this->myserver.sa, this->myserver.sa_size()) != len)
506 throw Exception("DNS: Unable to send query");
508 // Add timer for timeout
509 ServerInstance->Timers.AddTimer(req);
512 void RemoveRequest(DNS::Request* req) CXX11_OVERRIDE
514 if (requests[req->id] == req)
515 requests[req->id] = NULL;
518 std::string GetErrorStr(Error e) CXX11_OVERRIDE
523 return "Module is unloading";
525 return "Request timed out";
526 case ERROR_NOT_AN_ANSWER:
527 case ERROR_NONSTANDARD_QUERY:
528 case ERROR_FORMAT_ERROR:
529 case ERROR_MALFORMED:
530 return "Malformed answer";
531 case ERROR_SERVER_FAILURE:
532 case ERROR_NOT_IMPLEMENTED:
534 case ERROR_INVALIDTYPE:
535 return "Nameserver failure";
536 case ERROR_DOMAIN_NOT_FOUND:
537 case ERROR_NO_RECORDS:
538 return "Domain not found";
542 return "Unknown error";
546 void OnEventHandlerError(int errcode) CXX11_OVERRIDE
548 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "UDP socket got an error event");
551 void OnEventHandlerRead() CXX11_OVERRIDE
553 unsigned char buffer[524];
554 irc::sockets::sockaddrs from;
555 socklen_t x = sizeof(from);
557 int length = SocketEngine::RecvFrom(this, buffer, sizeof(buffer), 0, &from.sa, &x);
559 if (length < Packet::HEADER_LENGTH)
562 if (myserver != from)
564 std::string server1 = from.str();
565 std::string server2 = myserver.str();
566 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Got a result from the wrong server! Bad NAT or DNS forging attempt? '%s' != '%s'",
567 server1.c_str(), server2.c_str());
576 recv_packet.Fill(buffer, length);
579 catch (Exception& ex)
581 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, ex.GetReason());
584 // recv_packet.id must be filled in here
585 DNS::Request* request = this->requests[recv_packet.id];
588 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Received an answer for something we didn't request");
592 if (request->question != recv_packet.question)
594 // This can happen under high latency, drop it silently, do not fail the request
595 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Received an answer that isn't for a question we asked");
601 ServerInstance->stats.DnsBad++;
602 recv_packet.error = ERROR_MALFORMED;
603 request->OnError(&recv_packet);
605 else if (recv_packet.flags & QUERYFLAGS_OPCODE)
607 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Received a nonstandard query");
608 ServerInstance->stats.DnsBad++;
609 recv_packet.error = ERROR_NONSTANDARD_QUERY;
610 request->OnError(&recv_packet);
612 else if (!(recv_packet.flags & QUERYFLAGS_QR) || (recv_packet.flags & QUERYFLAGS_RCODE))
614 Error error = ERROR_UNKNOWN;
616 switch (recv_packet.flags & QUERYFLAGS_RCODE)
619 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "format error");
620 error = ERROR_FORMAT_ERROR;
623 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "server error");
624 error = ERROR_SERVER_FAILURE;
627 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "domain not found");
628 error = ERROR_DOMAIN_NOT_FOUND;
631 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "not implemented");
632 error = ERROR_NOT_IMPLEMENTED;
635 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "refused");
636 error = ERROR_REFUSED;
642 ServerInstance->stats.DnsBad++;
643 recv_packet.error = error;
644 request->OnError(&recv_packet);
646 else if (recv_packet.answers.empty())
648 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "No resource records returned");
649 ServerInstance->stats.DnsBad++;
650 recv_packet.error = ERROR_NO_RECORDS;
651 request->OnError(&recv_packet);
655 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Lookup complete for " + request->question.name);
656 ServerInstance->stats.DnsGood++;
657 request->OnLookupComplete(&recv_packet);
658 this->AddCache(recv_packet);
661 ServerInstance->stats.Dns++;
663 /* Request's destructor removes it from the request map */
667 bool Tick(time_t now) CXX11_OVERRIDE
669 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "cache: purging DNS cache");
671 for (cache_map::iterator it = this->cache.begin(); it != this->cache.end(); )
673 const Query& query = it->second;
674 if (IsExpired(query, now))
675 this->cache.erase(it++);
682 void Rehash(const std::string& dnsserver, std::string sourceaddr, unsigned int sourceport)
684 if (this->GetFd() > -1)
686 SocketEngine::Shutdown(this, 2);
687 SocketEngine::Close(this);
689 /* Remove expired entries from the cache */
690 this->Tick(ServerInstance->Time());
693 irc::sockets::aptosa(dnsserver, DNS::PORT, myserver);
695 /* Initialize mastersocket */
696 int s = socket(myserver.sa.sa_family, SOCK_DGRAM, 0);
699 /* Have we got a socket? */
700 if (this->GetFd() != -1)
702 SocketEngine::SetReuse(s);
703 SocketEngine::NonBlocking(s);
705 irc::sockets::sockaddrs bindto;
706 if (sourceaddr.empty())
708 // set a sourceaddr for irc::sockets::aptosa() based on the servers af type
709 if (myserver.sa.sa_family == AF_INET)
710 sourceaddr = "0.0.0.0";
711 else if (myserver.sa.sa_family == AF_INET6)
714 irc::sockets::aptosa(sourceaddr, sourceport, bindto);
716 if (SocketEngine::Bind(this->GetFd(), bindto) < 0)
719 ServerInstance->Logs->Log(MODNAME, LOG_SPARSE, "Error binding dns socket - hostnames will NOT resolve");
720 SocketEngine::Close(this->GetFd());
723 else if (!SocketEngine::AddFd(this, FD_WANT_POLL_READ | FD_WANT_NO_WRITE))
725 ServerInstance->Logs->Log(MODNAME, LOG_SPARSE, "Internal error starting DNS - hostnames will NOT resolve.");
726 SocketEngine::Close(this->GetFd());
730 if (bindto.sa.sa_family != myserver.sa.sa_family)
731 ServerInstance->Logs->Log(MODNAME, LOG_SPARSE, "Nameserver address family differs from source address family - hostnames might not resolve");
735 ServerInstance->Logs->Log(MODNAME, LOG_SPARSE, "Error creating DNS socket - hostnames will NOT resolve");
740 class ModuleDNS : public Module
743 std::string DNSServer;
744 std::string SourceIP;
745 unsigned int SourcePort;
750 // attempt to look up their nameserver from the system
751 ServerInstance->Logs->Log(MODNAME, LOG_DEFAULT, "WARNING: <dns:server> not defined, attempting to find a working server in the system settings...");
753 PFIXED_INFO pFixedInfo;
754 DWORD dwBufferSize = sizeof(FIXED_INFO);
755 pFixedInfo = (PFIXED_INFO) HeapAlloc(GetProcessHeap(), 0, sizeof(FIXED_INFO));
759 if (GetNetworkParams(pFixedInfo, &dwBufferSize) == ERROR_BUFFER_OVERFLOW)
761 HeapFree(GetProcessHeap(), 0, pFixedInfo);
762 pFixedInfo = (PFIXED_INFO) HeapAlloc(GetProcessHeap(), 0, dwBufferSize);
767 if (GetNetworkParams(pFixedInfo, &dwBufferSize) == NO_ERROR)
768 DNSServer = pFixedInfo->DnsServerList.IpAddress.String;
770 HeapFree(GetProcessHeap(), 0, pFixedInfo);
773 if (!DNSServer.empty())
775 ServerInstance->Logs->Log(MODNAME, LOG_DEFAULT, "<dns:server> set to '%s' as first active resolver in the system settings.", DNSServer.c_str());
780 ServerInstance->Logs->Log(MODNAME, LOG_DEFAULT, "No viable nameserver found! Defaulting to nameserver '127.0.0.1'!");
782 // attempt to look up their nameserver from /etc/resolv.conf
783 ServerInstance->Logs->Log(MODNAME, LOG_DEFAULT, "WARNING: <dns:server> not defined, attempting to find working server in /etc/resolv.conf...");
785 std::ifstream resolv("/etc/resolv.conf");
787 while (resolv >> DNSServer)
789 if (DNSServer == "nameserver")
792 if (DNSServer.find_first_not_of("0123456789.") == std::string::npos || DNSServer.find_first_not_of("0123456789ABCDEFabcdef:") == std::string::npos)
794 ServerInstance->Logs->Log(MODNAME, LOG_DEFAULT, "<dns:server> set to '%s' as first resolver in /etc/resolv.conf.",DNSServer.c_str());
800 ServerInstance->Logs->Log(MODNAME, LOG_DEFAULT, "/etc/resolv.conf contains no viable nameserver entries! Defaulting to nameserver '127.0.0.1'!");
802 DNSServer = "127.0.0.1";
806 ModuleDNS() : manager(this)
811 void ReadConfig(ConfigStatus& status) CXX11_OVERRIDE
813 std::string oldserver = DNSServer;
814 const std::string oldip = SourceIP;
815 const unsigned int oldport = SourcePort;
817 ConfigTag* tag = ServerInstance->Config->ConfValue("dns");
818 DNSServer = tag->getString("server");
819 SourceIP = tag->getString("sourceip");
820 SourcePort = tag->getInt("sourceport", 0, 0, 65535);
822 if (DNSServer.empty())
825 if (oldserver != DNSServer || oldip != SourceIP || oldport != SourcePort)
826 this->manager.Rehash(DNSServer, SourceIP, SourcePort);
829 void OnUnloadModule(Module* mod) CXX11_OVERRIDE
831 for (unsigned int i = 0; i <= MAX_REQUEST_ID; ++i)
833 DNS::Request* req = this->manager.requests[i];
837 if (req->creator == mod)
839 Query rr(req->question);
840 rr.error = ERROR_UNLOADED;
848 Version GetVersion() CXX11_OVERRIDE
850 return Version("DNS support", VF_CORE|VF_VENDOR);
854 MODULE_INIT(ModuleDNS)