X-Git-Url: https://git.netwichtig.de/gitweb/?a=blobdiff_plain;f=src%2Fcoremods%2Fcore_dns.cpp;h=8532179fbc995c4b9b4a65d75775fdd4be3d5dc1;hb=d2b94541fc95de18c25bf1b017c20d45cffb9f76;hp=8911f5b550bc0468798ea53a7020d944ab425e68;hpb=92959a48b05aa982d5b1331622cb28197d38e9da;p=user%2Fhenk%2Fcode%2Finspircd.git diff --git a/src/coremods/core_dns.cpp b/src/coremods/core_dns.cpp index 8911f5b55..8532179fb 100644 --- a/src/coremods/core_dns.cpp +++ b/src/coremods/core_dns.cpp @@ -27,9 +27,16 @@ #pragma comment(lib, "Iphlpapi.lib") #endif +namespace DNS +{ + /** Maximum value of a dns request id, 16 bits wide, 0xFFFF. + */ + const unsigned int MAX_REQUEST_ID = 0xFFFF; +} + using namespace DNS; -/** A full packet sent or recieved to/from the nameserver +/** A full packet sent or received to/from the nameserver */ class Packet : public Query { @@ -116,20 +123,20 @@ class Packet : public Query Question UnpackQuestion(const unsigned char* input, unsigned short input_size, unsigned short& pos) { - Question question; + Question q; - question.name = this->UnpackName(input, input_size, pos); + q.name = this->UnpackName(input, input_size, pos); if (pos + 4 > input_size) throw Exception("Unable to unpack question"); - question.type = static_cast(input[pos] << 8 | input[pos + 1]); + q.type = static_cast(input[pos] << 8 | input[pos + 1]); pos += 2; // Skip over query class code pos += 2; - return question; + return q; } ResourceRecord UnpackResourceRecord(const unsigned char* input, unsigned short input_size, unsigned short& pos) @@ -142,7 +149,7 @@ class Packet : public Query record.ttl = (input[pos] << 24) | (input[pos + 1] << 16) | (input[pos + 2] << 8) | input[pos + 3]; pos += 4; - //record.rdlength = input[pos] << 8 | input[pos + 1]; + uint16_t rdlength = input[pos] << 8 | input[pos + 1]; pos += 2; switch (record.type) @@ -183,6 +190,22 @@ class Packet : public Query case QUERY_PTR: { record.rdata = this->UnpackName(input, input_size, pos); + if (!InspIRCd::IsHost(record.rdata)) + throw Exception("Invalid name"); // XXX: Causes the request to time out + + break; + } + case QUERY_TXT: + { + if (pos + rdlength > input_size) + throw Exception("Unable to unpack txt resource record"); + + record.rdata = std::string(reinterpret_cast(input + pos), rdlength); + pos += rdlength; + + if (record.rdata.find_first_of("\r\n\0", 0, 3) != std::string::npos) + throw Exception("Invalid character in txt record"); + break; } default: @@ -239,8 +262,7 @@ class Packet : public Query if (qdcount != 1) throw Exception("Question count != 1 in incoming packet"); - for (unsigned i = 0; i < qdcount; ++i) - this->questions.push_back(this->UnpackQuestion(input, len, packet_pos)); + this->question = this->UnpackQuestion(input, len, packet_pos); for (unsigned i = 0; i < ancount; ++i) this->answers.push_back(this->UnpackResourceRecord(input, len, packet_pos)); @@ -257,8 +279,8 @@ class Packet : public Query output[pos++] = this->id & 0xFF; output[pos++] = this->flags >> 8; output[pos++] = this->flags & 0xFF; - output[pos++] = this->questions.size() >> 8; - output[pos++] = this->questions.size() & 0xFF; + output[pos++] = 0; // Question count, high byte + output[pos++] = 1; // Question count, low byte output[pos++] = 0; // Answer count, high byte output[pos++] = 0; // Answer count, low byte output[pos++] = 0; @@ -266,9 +288,8 @@ class Packet : public Query output[pos++] = 0; output[pos++] = 0; - for (unsigned i = 0; i < this->questions.size(); ++i) { - Question& q = this->questions[i]; + Question& q = this->question; if (q.type == QUERY_PTR) { @@ -325,6 +346,11 @@ class MyManager : public Manager, public Timer, public EventHandler cache_map cache; irc::sockets::sockaddrs myserver; + bool unloading; + + /** Maximum number of entries in cache + */ + static const unsigned int MAX_CACHE_SIZE = 1000; static bool IsExpired(const Query& record, time_t now = ServerInstance->Time()) { @@ -361,15 +387,31 @@ class MyManager : public Manager, public Timer, public EventHandler */ void AddCache(Query& r) { - const ResourceRecord& rr = r.answers[0]; + if (cache.size() >= MAX_CACHE_SIZE) + cache.clear(); + + // Determine the lowest TTL value and use that as the TTL of the cache entry + unsigned int cachettl = UINT_MAX; + for (std::vector::const_iterator i = r.answers.begin(); i != r.answers.end(); ++i) + { + const ResourceRecord& rr = *i; + if (rr.ttl < cachettl) + cachettl = rr.ttl; + } + + cachettl = std::min(cachettl, (unsigned int)5*60); + ResourceRecord& rr = r.answers.front(); + // Set TTL to what we've determined to be the lowest + rr.ttl = cachettl; ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "cache: added cache for " + rr.name + " -> " + rr.rdata + " ttl: " + ConvToStr(rr.ttl)); - this->cache[r.questions[0]] = r; + this->cache[r.question] = r; } public: DNS::Request* requests[MAX_REQUEST_ID+1]; - MyManager(Module* c) : Manager(c), Timer(3600, true) + MyManager(Module* c) : Manager(c), Timer(5*60, true) + , unloading(false) { for (unsigned int i = 0; i <= MAX_REQUEST_ID; ++i) requests[i] = NULL; @@ -378,13 +420,16 @@ class MyManager : public Manager, public Timer, public EventHandler ~MyManager() { + // Ensure Process() will fail for new requests + unloading = true; + for (unsigned int i = 0; i <= MAX_REQUEST_ID; ++i) { DNS::Request* request = requests[i]; if (!request) continue; - Query rr(*request); + Query rr(request->question); rr.error = ERROR_UNKNOWN; request->OnError(&rr); @@ -392,9 +437,12 @@ class MyManager : public Manager, public Timer, public EventHandler } } - void Process(DNS::Request* req) + void Process(DNS::Request* req) CXX11_OVERRIDE { - ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Processing request to lookup " + req->name + " of type " + ConvToStr(req->type) + " to " + this->myserver.addr()); + if ((unloading) || (req->creator->dying)) + throw Exception("Module is being unloaded"); + + ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Processing request to lookup " + req->question.name + " of type " + ConvToStr(req->question.type) + " to " + this->myserver.addr()); /* Create an id */ unsigned int tries = 0; @@ -431,31 +479,38 @@ class MyManager : public Manager, public Timer, public EventHandler Packet p; p.flags = QUERYFLAGS_RD; p.id = req->id; - p.questions.push_back(*req); + p.question = req->question; unsigned char buffer[524]; unsigned short len = p.Pack(buffer, sizeof(buffer)); - /* Note that calling Pack() above can actually change the contents of p.questions[0].name, if the query is a PTR, + /* Note that calling Pack() above can actually change the contents of p.question.name, if the query is a PTR, * to contain the value that would be in the DNS cache, which is why this is here. */ - if (req->use_cache && this->CheckCache(req, p.questions[0])) + if (req->use_cache && this->CheckCache(req, p.question)) { ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Using cached result"); delete req; return; } - if (SocketEngine::SendTo(this, buffer, len, 0, &this->myserver.sa, this->myserver.sa_size()) != len) + // Update name in the original request so question checking works for PTR queries + req->question.name = p.question.name; + + if (SocketEngine::SendTo(this, buffer, len, 0, this->myserver) != len) throw Exception("DNS: Unable to send query"); + + // Add timer for timeout + ServerInstance->Timers.AddTimer(req); } - void RemoveRequest(DNS::Request* req) + void RemoveRequest(DNS::Request* req) CXX11_OVERRIDE { - this->requests[req->id] = NULL; + if (requests[req->id] == req) + requests[req->id] = NULL; } - std::string GetErrorStr(Error e) + std::string GetErrorStr(Error e) CXX11_OVERRIDE { switch (e) { @@ -466,6 +521,7 @@ class MyManager : public Manager, public Timer, public EventHandler case ERROR_NOT_AN_ANSWER: case ERROR_NONSTANDARD_QUERY: case ERROR_FORMAT_ERROR: + case ERROR_MALFORMED: return "Malformed answer"; case ERROR_SERVER_FAILURE: case ERROR_NOT_IMPLEMENTED: @@ -508,17 +564,19 @@ class MyManager : public Manager, public Timer, public EventHandler } Packet recv_packet; + bool valid = false; try { recv_packet.Fill(buffer, length); + valid = true; } catch (Exception& ex) { ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, ex.GetReason()); - return; } + // recv_packet.id must be filled in here DNS::Request* request = this->requests[recv_packet.id]; if (request == NULL) { @@ -526,14 +584,27 @@ class MyManager : public Manager, public Timer, public EventHandler return; } - if (recv_packet.flags & QUERYFLAGS_OPCODE) + if (request->question != recv_packet.question) + { + // This can happen under high latency, drop it silently, do not fail the request + ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Received an answer that isn't for a question we asked"); + return; + } + + if (!valid) + { + ServerInstance->stats.DnsBad++; + recv_packet.error = ERROR_MALFORMED; + request->OnError(&recv_packet); + } + else if (recv_packet.flags & QUERYFLAGS_OPCODE) { ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Received a nonstandard query"); ServerInstance->stats.DnsBad++; recv_packet.error = ERROR_NONSTANDARD_QUERY; request->OnError(&recv_packet); } - else if (recv_packet.flags & QUERYFLAGS_RCODE) + else if (!(recv_packet.flags & QUERYFLAGS_QR) || (recv_packet.flags & QUERYFLAGS_RCODE)) { Error error = ERROR_UNKNOWN; @@ -567,7 +638,7 @@ class MyManager : public Manager, public Timer, public EventHandler recv_packet.error = error; request->OnError(&recv_packet); } - else if (recv_packet.questions.empty() || recv_packet.answers.empty()) + else if (recv_packet.answers.empty()) { ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "No resource records returned"); ServerInstance->stats.DnsBad++; @@ -576,7 +647,7 @@ class MyManager : public Manager, public Timer, public EventHandler } else { - ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Lookup complete for " + request->name); + ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Lookup complete for " + request->question.name); ServerInstance->stats.DnsGood++; request->OnLookupComplete(&recv_packet); this->AddCache(recv_packet); @@ -588,7 +659,7 @@ class MyManager : public Manager, public Timer, public EventHandler delete request; } - bool Tick(time_t now) + bool Tick(time_t now) CXX11_OVERRIDE { ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "cache: purging DNS cache"); @@ -603,7 +674,7 @@ class MyManager : public Manager, public Timer, public EventHandler return true; } - void Rehash(const std::string& dnsserver) + void Rehash(const std::string& dnsserver, std::string sourceaddr, unsigned int sourceport) { if (this->GetFd() > -1) { @@ -617,7 +688,7 @@ class MyManager : public Manager, public Timer, public EventHandler irc::sockets::aptosa(dnsserver, DNS::PORT, myserver); /* Initialize mastersocket */ - int s = socket(myserver.sa.sa_family, SOCK_DGRAM, 0); + int s = socket(myserver.family(), SOCK_DGRAM, 0); this->SetFd(s); /* Have we got a socket? */ @@ -627,8 +698,15 @@ class MyManager : public Manager, public Timer, public EventHandler SocketEngine::NonBlocking(s); irc::sockets::sockaddrs bindto; - memset(&bindto, 0, sizeof(bindto)); - bindto.sa.sa_family = myserver.sa.sa_family; + if (sourceaddr.empty()) + { + // set a sourceaddr for irc::sockets::aptosa() based on the servers af type + if (myserver.family() == AF_INET) + sourceaddr = "0.0.0.0"; + else if (myserver.family() == AF_INET6) + sourceaddr = "::"; + } + irc::sockets::aptosa(sourceaddr, sourceport, bindto); if (SocketEngine::Bind(this->GetFd(), bindto) < 0) { @@ -643,6 +721,9 @@ class MyManager : public Manager, public Timer, public EventHandler SocketEngine::Close(this->GetFd()); this->SetFd(-1); } + + if (bindto.family() != myserver.family()) + ServerInstance->Logs->Log(MODNAME, LOG_SPARSE, "Nameserver address family differs from source address family - hostnames might not resolve"); } else { @@ -655,12 +736,14 @@ class ModuleDNS : public Module { MyManager manager; std::string DNSServer; + std::string SourceIP; + unsigned int SourcePort; void FindDNSServer() { #ifdef _WIN32 // attempt to look up their nameserver from the system - ServerInstance->Logs->Log("CONFIG", LOG_DEFAULT, "WARNING: not defined, attempting to find a working server in the system settings..."); + ServerInstance->Logs->Log(MODNAME, LOG_DEFAULT, "WARNING: not defined, attempting to find a working server in the system settings..."); PFIXED_INFO pFixedInfo; DWORD dwBufferSize = sizeof(FIXED_INFO); @@ -684,15 +767,15 @@ class ModuleDNS : public Module if (!DNSServer.empty()) { - ServerInstance->Logs->Log("CONFIG", LOG_DEFAULT, " set to '%s' as first active resolver in the system settings.", DNSServer.c_str()); + ServerInstance->Logs->Log(MODNAME, LOG_DEFAULT, " set to '%s' as first active resolver in the system settings.", DNSServer.c_str()); return; } } - ServerInstance->Logs->Log("CONFIG", LOG_DEFAULT, "No viable nameserver found! Defaulting to nameserver '127.0.0.1'!"); + ServerInstance->Logs->Log(MODNAME, LOG_DEFAULT, "No viable nameserver found! Defaulting to nameserver '127.0.0.1'!"); #else // attempt to look up their nameserver from /etc/resolv.conf - ServerInstance->Logs->Log("CONFIG", LOG_DEFAULT, "WARNING: not defined, attempting to find working server in /etc/resolv.conf..."); + ServerInstance->Logs->Log(MODNAME, LOG_DEFAULT, "WARNING: not defined, attempting to find working server in /etc/resolv.conf..."); std::ifstream resolv("/etc/resolv.conf"); @@ -701,36 +784,44 @@ class ModuleDNS : public Module if (DNSServer == "nameserver") { resolv >> DNSServer; - if (DNSServer.find_first_not_of("0123456789.") == std::string::npos) + if (DNSServer.find_first_not_of("0123456789.") == std::string::npos || DNSServer.find_first_not_of("0123456789ABCDEFabcdef:") == std::string::npos) { - ServerInstance->Logs->Log("CONFIG", LOG_DEFAULT, " set to '%s' as first resolver in /etc/resolv.conf.",DNSServer.c_str()); + ServerInstance->Logs->Log(MODNAME, LOG_DEFAULT, " set to '%s' as first resolver in /etc/resolv.conf.",DNSServer.c_str()); return; } } } - ServerInstance->Logs->Log("CONFIG", LOG_DEFAULT, "/etc/resolv.conf contains no viable nameserver entries! Defaulting to nameserver '127.0.0.1'!"); + ServerInstance->Logs->Log(MODNAME, LOG_DEFAULT, "/etc/resolv.conf contains no viable nameserver entries! Defaulting to nameserver '127.0.0.1'!"); #endif DNSServer = "127.0.0.1"; } public: - ModuleDNS() : manager(this) + ModuleDNS() : manager(this) + , SourcePort(0) { } void ReadConfig(ConfigStatus& status) CXX11_OVERRIDE { std::string oldserver = DNSServer; - DNSServer = ServerInstance->Config->ConfValue("dns")->getString("server"); + const std::string oldip = SourceIP; + const unsigned int oldport = SourcePort; + + ConfigTag* tag = ServerInstance->Config->ConfValue("dns"); + DNSServer = tag->getString("server"); + SourceIP = tag->getString("sourceip"); + SourcePort = tag->getUInt("sourceport", 0, 0, UINT16_MAX); + if (DNSServer.empty()) FindDNSServer(); - if (oldserver != DNSServer) - this->manager.Rehash(DNSServer); + if (oldserver != DNSServer || oldip != SourceIP || oldport != SourcePort) + this->manager.Rehash(DNSServer, SourceIP, SourcePort); } - void OnUnloadModule(Module* mod) + void OnUnloadModule(Module* mod) CXX11_OVERRIDE { for (unsigned int i = 0; i <= MAX_REQUEST_ID; ++i) { @@ -740,7 +831,7 @@ class ModuleDNS : public Module if (req->creator == mod) { - Query rr(*req); + Query rr(req->question); rr.error = ERROR_UNLOADED; req->OnError(&rr); @@ -749,9 +840,9 @@ class ModuleDNS : public Module } } - Version GetVersion() + Version GetVersion() CXX11_OVERRIDE { - return Version("DNS support", VF_CORE|VF_VENDOR); + return Version("Provides support for DNS lookups", VF_CORE|VF_VENDOR); } };