X-Git-Url: https://git.netwichtig.de/gitweb/?a=blobdiff_plain;f=src%2Fcoremods%2Fcore_dns.cpp;h=b16658242212df098ef1639a91096fddfa61aa1c;hb=e2b0f3dc9ef4d56c71d7abda13e6139ca092e387;hp=d4214b9a5ec313be8b354063cd5072e8a7d33d56;hpb=3d32852e7e459d403179e8f79354e2e52bbc4a52;p=user%2Fhenk%2Fcode%2Finspircd.git diff --git a/src/coremods/core_dns.cpp b/src/coremods/core_dns.cpp index d4214b9a5..b16658242 100644 --- a/src/coremods/core_dns.cpp +++ b/src/coremods/core_dns.cpp @@ -1,8 +1,10 @@ /* * InspIRCd -- Internet Relay Chat Daemon * - * Copyright (C) 2013 Adam - * Copyright (C) 2003-2013 Anope Team + * Copyright (C) 2019 Robby + * Copyright (C) 2015, 2017-2021 Sadie Powell + * Copyright (C) 2013-2016 Attila Molnar + * Copyright (C) 2013, 2015-2016 Adam * * This file is part of InspIRCd. InspIRCd is free software: you can * redistribute it and/or modify it under the terms of the GNU General Public @@ -27,9 +29,16 @@ #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 { @@ -142,7 +151,7 @@ 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 +192,22 @@ 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: @@ -323,6 +348,11 @@ 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()) { @@ -359,7 +389,22 @@ 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.question] = r; } @@ -367,7 +412,8 @@ class MyManager : public Manager, public Timer, public EventHandler 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; @@ -376,13 +422,17 @@ class MyManager : public Manager, public Timer, public EventHandler ~MyManager() { + // Ensure Process() will fail for new requests + Close(); + 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); @@ -390,9 +440,33 @@ class MyManager : public Manager, public Timer, public EventHandler } } - void Process(DNS::Request* req) + void Close() { - ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Processing request to lookup " + req->name + " of type " + ConvToStr(req->type) + " to " + this->myserver.addr()); + // Shutdown the socket if it exists. + if (HasFd()) + { + SocketEngine::Shutdown(this, 2); + SocketEngine::Close(this); + } + + // Remove all entries from the cache. + cache.clear(); + } + + void Process(DNS::Request* req) CXX11_OVERRIDE + { + if ((unloading) || (req->creator->dying)) + throw Exception("Module is being unloaded"); + + if (!HasFd()) + { + Query rr(req->question); + rr.error = ERROR_DISABLED; + req->OnError(&rr); + return; + } + + 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; @@ -429,7 +503,7 @@ class MyManager : public Manager, public Timer, public EventHandler Packet p; p.flags = QUERYFLAGS_RD; p.id = req->id; - p.question = *req; + p.question = req->question; unsigned char buffer[524]; unsigned short len = p.Pack(buffer, sizeof(buffer)); @@ -445,18 +519,22 @@ class MyManager : public Manager, public Timer, public EventHandler } // Update name in the original request so question checking works for PTR queries - req->name = p.question.name; + req->question.name = p.question.name; - if (SocketEngine::SendTo(this, buffer, len, 0, &this->myserver.sa, this->myserver.sa_size()) != len) + 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) { @@ -467,6 +545,7 @@ 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: @@ -476,6 +555,8 @@ class MyManager : public Manager, public Timer, public EventHandler case ERROR_DOMAIN_NOT_FOUND: case ERROR_NO_RECORDS: return "Domain not found"; + case ERROR_DISABLED: + return "DNS lookups are disabled"; case ERROR_NONE: case ERROR_UNKNOWN: default: @@ -483,6 +564,25 @@ class MyManager : public Manager, public Timer, public EventHandler } } + std::string GetTypeStr(QueryType qt) CXX11_OVERRIDE + { + switch (qt) + { + case QUERY_A: + return "A"; + case QUERY_AAAA: + return "AAAA"; + case QUERY_CNAME: + return "CNAME"; + case QUERY_PTR: + return "PTR"; + case QUERY_TXT: + return "TXT"; + default: + return "UNKNOWN"; + } + } + void OnEventHandlerError(int errcode) CXX11_OVERRIDE { ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "UDP socket got an error event"); @@ -509,17 +609,19 @@ 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) { @@ -527,21 +629,27 @@ class MyManager : public Manager, public Timer, public EventHandler return; } - if (static_cast(*request) != recv_packet.question) + 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 (recv_packet.flags & QUERYFLAGS_OPCODE) + 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; @@ -584,7 +692,7 @@ 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); @@ -596,47 +704,52 @@ 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"); - + unsigned long expired = 0; for (cache_map::iterator it = this->cache.begin(); it != this->cache.end(); ) { const Query& query = it->second; if (IsExpired(query, now)) + { + expired++; this->cache.erase(it++); + } else ++it; } + + if (expired) + ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "cache: purged %lu expired DNS entries", expired); + return true; } - void Rehash(const std::string& dnsserver) + void Rehash(const std::string& dnsserver, std::string sourceaddr, unsigned int sourceport) { - if (this->GetFd() > -1) - { - SocketEngine::Shutdown(this, 2); - SocketEngine::Close(this); - - /* Remove expired entries from the cache */ - this->Tick(ServerInstance->Time()); - } - irc::sockets::aptosa(dnsserver, DNS::PORT, myserver); /* Initialize mastersocket */ - int s = socket(myserver.sa.sa_family, SOCK_DGRAM, 0); + Close(); + int s = socket(myserver.family(), SOCK_DGRAM, 0); this->SetFd(s); /* Have we got a socket? */ - if (this->GetFd() != -1) + if (this->HasFd()) { SocketEngine::SetReuse(s); 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) { @@ -651,6 +764,9 @@ 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 { @@ -663,12 +779,14 @@ 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); @@ -692,15 +810,15 @@ 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"); @@ -709,36 +827,56 @@ 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"); + ConfigTag* tag = ServerInstance->Config->ConfValue("dns"); + if (!tag->getBool("enabled", true)) + { + // Clear these so they get reset if DNS is enabled again. + DNSServer.clear(); + SourceIP.clear(); + SourcePort = 0; + + this->manager.Close(); + return; + } + + const std::string oldserver = DNSServer; + DNSServer = tag->getString("server"); + + const std::string oldip = SourceIP; + SourceIP = tag->getString("sourceip"); + + const unsigned int oldport = SourcePort; + 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) { @@ -748,7 +886,7 @@ class ModuleDNS : public Module if (req->creator == mod) { - Query rr(*req); + Query rr(req->question); rr.error = ERROR_UNLOADED; req->OnError(&rr); @@ -757,9 +895,9 @@ 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); } };