X-Git-Url: https://git.netwichtig.de/gitweb/?a=blobdiff_plain;f=src%2Fdns.cpp;h=ea6b000a9e3d788373b571feb731475fdffa29e7;hb=09c716ce117e3c89b4da7ab88f4caaefb43511b5;hp=52e5419679780a6788d5e1ddb5a9487b5ff37bd8;hpb=ec99b87f5bb800371bf3e236836b6c74bc07eee6;p=user%2Fhenk%2Fcode%2Finspircd.git diff --git a/src/dns.cpp b/src/dns.cpp index 52e541967..3d3bc947f 100644 --- a/src/dns.cpp +++ b/src/dns.cpp @@ -1,19 +1,29 @@ -/* +------------------------------------+ - * | Inspire Internet Relay Chat Daemon | - * +------------------------------------+ +/* + * InspIRCd -- Internet Relay Chat Daemon + * + * Copyright (C) 2012 William Pitcock + * Copyright (C) 2009-2010 Daniel De Graaf + * Copyright (C) 2006, 2009 Robin Burchell + * Copyright (C) 2007, 2009 Dennis Friis + * Copyright (C) 2008 Thomas Stagner + * Copyright (C) 2005-2007 Craig Edwards * - * InspIRCd is copyright (C) 2002-2006 ChatSpike-Dev. - * E-mail: - * - * - * - * Written by Craig Edwards, Craig McLure, and others. - * This program is free but copyrighted software; see - * the file COPYING for details. + * 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 + * License as published by the Free Software Foundation, version 2. * - * --------------------------------------------------- + * This program is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS + * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more + * details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see . */ + +/* $Core */ + /* dns.cpp - Nonblocking DNS functions. Very very loosely based on the firedns library, @@ -24,39 +34,32 @@ Please do not assume that firedns works like this, looks like this, walks like this or tastes like this. */ -using namespace std; - -#include -#include +#ifndef _WIN32 #include #include #include -#include -#include #include #include -#include -#include "dns.h" +#else +#include "inspircd_win32wrapper.h" +#endif + #include "inspircd.h" -#include "helperfuncs.h" -#include "inspircd_config.h" #include "socketengine.h" #include "configreader.h" +#include "socket.h" -/* We need these */ -extern InspIRCd* ServerInstance; -extern ServerConfig* Config; - -/* Master file descriptor */ -int DNS::MasterSocket; +#define DN_COMP_BITMASK 0xC000 /* highest 6 bits in a DN label header */ -/* Masks to mask off the responses we get from the DNSRequest methods */ +/** Masks to mask off the responses we get from the DNSRequest methods + */ enum QueryInfo { ERROR_MASK = 0x10000 /* Result is an error */ }; -/* Flags which can be ORed into a request or reply for different meanings */ +/** Flags which can be ORed into a request or reply for different meanings + */ enum QueryFlags { FLAGS_MASK_RD = 0x01, /* Recursive */ @@ -70,17 +73,17 @@ enum QueryFlags }; -/* Represents a dns resource record (rr) */ -class ResourceRecord +/** Represents a dns resource record (rr) + */ +struct ResourceRecord { - public: QueryType type; /* Record type */ unsigned int rr_class; /* Record class */ unsigned long ttl; /* Time to live */ unsigned int rdlength; /* Record length */ }; -/* Represents a dns request/reply header, and its payload as opaque data. +/** Represents a dns request/reply header, and its payload as opaque data. */ class DNSHeader { @@ -95,40 +98,101 @@ class DNSHeader unsigned char payload[512]; /* Packet payload */ }; -/* Represents a request 'on the wire' with routing information relating to - * where to call when we get a result - */ class DNSRequest { public: unsigned char id[2]; /* Request id */ - unsigned char* res; /* Result processing buffer */ - unsigned int rr_class; /* Request class */ + unsigned char* res; /* Result processing buffer */ + unsigned int rr_class; /* Request class */ QueryType type; /* Request type */ - insp_inaddr myserver; /* DNS server address*/ + DNS* dnsobj; /* DNS caller (where we get our FD from) */ + unsigned long ttl; /* Time to live */ + std::string orig; /* Original requested name/ip */ + + DNSRequest(DNS* dns, int id, const std::string &original); + ~DNSRequest(); + DNSInfo ResultIsReady(DNSHeader &h, unsigned length); + int SendRequests(const DNSHeader *header, const int length, QueryType qt); +}; + +class CacheTimer : public Timer +{ + private: + DNS* dns; + public: + CacheTimer(DNS* thisdns) + : Timer(5*60, ServerInstance->Time(), true), dns(thisdns) { } - /* Allocate the processing buffer */ - DNSRequest(insp_inaddr server) + virtual void Tick(time_t) { - res = new unsigned char[512]; - *res = 0; - memcpy(&myserver, &server, sizeof(insp_inaddr)); + dns->PruneCache(); } +}; - /* Deallocate the processing buffer */ - ~DNSRequest() +class RequestTimeout : public Timer +{ + DNSRequest* watch; + int watchid; + public: + RequestTimeout(unsigned long n, DNSRequest* watching, int id) : Timer(n, ServerInstance->Time()), watch(watching), watchid(id) { - delete[] res; + } + ~RequestTimeout() + { + if (ServerInstance->Res) + Tick(0); } - /* Called when a result is ready to be processed which matches this id */ - DNSInfo ResultIsReady(DNSHeader &h, int length); - - /* Called when there are requests to be sent out */ - int SendRequests(const DNSHeader *header, const int length, QueryType qt); + void Tick(time_t) + { + if (ServerInstance->Res->requests[watchid] == watch) + { + /* Still exists, whack it */ + if (ServerInstance->Res->Classes[watchid]) + { + ServerInstance->Res->Classes[watchid]->OnError(RESOLVER_TIMEOUT, "Request timed out"); + delete ServerInstance->Res->Classes[watchid]; + ServerInstance->Res->Classes[watchid] = NULL; + } + ServerInstance->Res->requests[watchid] = NULL; + delete watch; + } + } }; -/* Fill a ResourceRecord class based on raw data input */ +CachedQuery::CachedQuery(const std::string &res, QueryType qt, unsigned int ttl) : data(res), type(qt) +{ + if (ttl > 5*60) + ttl = 5*60; + expires = ServerInstance->Time() + ttl; +} + +int CachedQuery::CalcTTLRemaining() +{ + int n = expires - ServerInstance->Time(); + return (n < 0 ? 0 : n); +} + +/* Allocate the processing buffer */ +DNSRequest::DNSRequest(DNS* dns, int rid, const std::string &original) : dnsobj(dns) +{ + /* hardening against overflow here: make our work buffer twice the theoretical + * maximum size so that hostile input doesn't screw us over. + */ + res = new unsigned char[sizeof(DNSHeader) * 2]; + *res = 0; + orig = original; + RequestTimeout* RT = new RequestTimeout(ServerInstance->Config->dns_timeout ? ServerInstance->Config->dns_timeout : 5, this, rid); + ServerInstance->Timers->AddTimer(RT); /* The timer manager frees this */ +} + +/* Deallocate the processing buffer */ +DNSRequest::~DNSRequest() +{ + delete[] res; +} + +/** Fill a ResourceRecord class based on raw data input */ inline void DNS::FillResourceRecord(ResourceRecord* rr, const unsigned char *input) { rr->type = (QueryType)((input[0] << 8) + input[1]); @@ -137,7 +201,7 @@ inline void DNS::FillResourceRecord(ResourceRecord* rr, const unsigned char *inp rr->rdlength = (input[8] << 8) + input[9]; } -/* Fill a DNSHeader class based on raw data input of a given length */ +/** Fill a DNSHeader class based on raw data input of a given length */ inline void DNS::FillHeader(DNSHeader *header, const unsigned char *input, const int length) { header->id[0] = input[0]; @@ -151,7 +215,7 @@ inline void DNS::FillHeader(DNSHeader *header, const unsigned char *input, const memcpy(header->payload,&input[12],length); } -/* Empty a DNSHeader class out into raw data, ready for transmission */ +/** Empty a DNSHeader class out into raw data, ready for transmission */ inline void DNS::EmptyHeader(unsigned char *output, const DNSHeader *header, const int length) { output[0] = header->id[0]; @@ -169,51 +233,58 @@ inline void DNS::EmptyHeader(unsigned char *output, const DNSHeader *header, con memcpy(&output[12],header->payload,length); } -/* Send requests we have previously built down the UDP socket */ +/** Send requests we have previously built down the UDP socket */ int DNSRequest::SendRequests(const DNSHeader *header, const int length, QueryType qt) { - insp_sockaddr addr; + ServerInstance->Logs->Log("RESOLVER", DEBUG,"DNSRequest::SendRequests"); + unsigned char payload[sizeof(DNSHeader)]; this->rr_class = 1; this->type = qt; - + DNS::EmptyHeader(payload,header,length); - memset(&addr,0,sizeof(addr)); -#ifdef IPV6 - memcpy(&addr.sin6_addr,&myserver,sizeof(addr.sin6_addr)); - addr.sin6_family = AF_FAMILY; - addr.sin6_port = htons(DNS::QUERY_PORT); -#else - memcpy(&addr.sin_addr.s_addr,&myserver,sizeof(addr.sin_addr)); - addr.sin_family = AF_FAMILY; - addr.sin_port = htons(DNS::QUERY_PORT); -#endif - if (sendto(DNS::GetMasterSocket(), payload, length + 12, 0, (sockaddr *) &addr, sizeof(addr)) == -1) - { - log(DEBUG,"Error in sendto!"); + if (ServerInstance->SE->SendTo(dnsobj, payload, length + 12, 0, &(dnsobj->myserver.sa), sa_size(dnsobj->myserver)) != length+12) return -1; - } + ServerInstance->Logs->Log("RESOLVER",DEBUG,"Sent OK"); return 0; } -/* Add a query with a predefined header, and allocate an ID for it. */ -DNSRequest* DNS::AddQuery(DNSHeader *header, int &id) +/** Add a query with a predefined header, and allocate an ID for it. */ +DNSRequest* DNS::AddQuery(DNSHeader *header, int &id, const char* original) { - /* Are there already the max number of requests on the go? */ - if (requests.size() == DNS::MAX_REQUEST_ID + 1) + /* Is the DNS connection down? */ + if (this->GetFd() == -1) return NULL; - + /* Create an id */ - id = this->PRNG() & DNS::MAX_REQUEST_ID; + unsigned int tries = 0; + do { + id = ServerInstance->GenRandomInt(DNS::MAX_REQUEST_ID); + if (++tries == DNS::MAX_REQUEST_ID*5) + { + // If we couldn't find an empty slot this many times, do a sequential scan as a last + // resort. If an empty slot is found that way, go on, otherwise throw an exception + id = -1; + for (int i = 0; i < DNS::MAX_REQUEST_ID; i++) + { + if (!requests[i]) + { + id = i; + break; + } + } - /* If this id is already 'in flight', pick another. */ - while (requests.find(id) != requests.end()) - id = this->PRNG() & DNS::MAX_REQUEST_ID; + if (id == -1) + throw ModuleException("DNS: All ids are in use"); - DNSRequest* req = new DNSRequest(this->myserver); + break; + } + } while (requests[id]); + + DNSRequest* req = new DNSRequest(this, id, original); header->id[0] = req->id[0] = id >> 8; header->id[1] = req->id[1] = id & 0xFF; @@ -233,79 +304,114 @@ DNSRequest* DNS::AddQuery(DNSHeader *header, int &id) return req; } -int DNS::GetMasterSocket() +int DNS::ClearCache() { - return MasterSocket; + /* This ensures the buckets are reset to sane levels */ + int rv = this->cache->size(); + delete this->cache; + this->cache = new dnscache(); + return rv; } -/* Initialise the DNS UDP socket so that we can send requests */ -DNS::DNS() +int DNS::PruneCache() { - insp_inaddr addr; + int n = 0; + dnscache* newcache = new dnscache(); + for (dnscache::iterator i = this->cache->begin(); i != this->cache->end(); i++) + /* Dont include expired items (theres no point) */ + if (i->second.CalcTTLRemaining()) + newcache->insert(*i); + else + n++; - /* Clear the Resolver class table */ - memset(Classes,0,sizeof(Classes)); + delete this->cache; + this->cache = newcache; + return n; +} - /* Set the id of the next request to 0 - */ - currid = 0; +void DNS::Rehash() +{ + if (this->GetFd() > -1) + { + ServerInstance->SE->DelFd(this); + ServerInstance->SE->Shutdown(this, 2); + ServerInstance->SE->Close(this); + this->SetFd(-1); - /* Clear the namesever address */ - memset(&myserver,0,sizeof(insp_inaddr)); + /* Rehash the cache */ + this->PruneCache(); + } + else + { + /* Create initial dns cache */ + this->cache = new dnscache(); + } - /* Convert the nameserver address into an insp_inaddr */ - if (insp_aton(Config->DNSServer,&addr) > 0) - memcpy(&myserver,&addr,sizeof(insp_inaddr)); + irc::sockets::aptosa(ServerInstance->Config->DNSServer, DNS::QUERY_PORT, myserver); /* Initialize mastersocket */ - MasterSocket = socket(PF_PROTOCOL, SOCK_DGRAM, 0); - if (MasterSocket != -1) - { - /* Did it succeed? */ - if (fcntl(MasterSocket, F_SETFL, O_NONBLOCK) != 0) - { - /* Couldn't make the socket nonblocking */ - shutdown(MasterSocket,2); - close(MasterSocket); - MasterSocket = -1; - } - } + int s = socket(myserver.sa.sa_family, SOCK_DGRAM, 0); + this->SetFd(s); + /* Have we got a socket and is it nonblocking? */ - if (MasterSocket != -1) - { -#ifdef IPV6 - insp_sockaddr addr; - memset(&addr,0,sizeof(addr)); - addr.sin6_family = AF_FAMILY; - addr.sin6_port = 0; - memset(&addr.sin6_addr,255,sizeof(in6_addr)); -#else - insp_sockaddr addr; - memset(&addr,0,sizeof(addr)); - addr.sin_family = AF_FAMILY; - addr.sin_port = 0; - addr.sin_addr.s_addr = INADDR_ANY; -#endif - /* Bind the port */ - if (bind(MasterSocket,(sockaddr *)&addr,sizeof(addr)) != 0) + if (this->GetFd() != -1) + { + ServerInstance->SE->SetReuse(s); + ServerInstance->SE->NonBlocking(s); + irc::sockets::sockaddrs bindto; + memset(&bindto, 0, sizeof(bindto)); + bindto.sa.sa_family = myserver.sa.sa_family; + if (ServerInstance->SE->Bind(this->GetFd(), bindto) < 0) { /* Failed to bind */ - log(DEBUG,"Cant bind DNS::MasterSocket"); - shutdown(MasterSocket,2); - close(MasterSocket); - MasterSocket = -1; + ServerInstance->Logs->Log("RESOLVER",SPARSE,"Error binding dns socket - hostnames will NOT resolve"); + ServerInstance->SE->Shutdown(this, 2); + ServerInstance->SE->Close(this); + this->SetFd(-1); } - - if (MasterSocket >= 0) + else if (!ServerInstance->SE->AddFd(this, FD_WANT_POLL_READ | FD_WANT_NO_WRITE)) { - /* Hook the descriptor into the socket engine */ - if (ServerInstance && ServerInstance->SE) - ServerInstance->SE->AddFd(MasterSocket,true,X_ESTAB_DNS); + ServerInstance->Logs->Log("RESOLVER",SPARSE,"Internal error starting DNS - hostnames will NOT resolve."); + ServerInstance->SE->Shutdown(this, 2); + ServerInstance->SE->Close(this); + this->SetFd(-1); } } + else + { + ServerInstance->Logs->Log("RESOLVER",SPARSE,"Error creating DNS socket - hostnames will NOT resolve"); + } +} + +/** Initialise the DNS UDP socket so that we can send requests */ +DNS::DNS() +{ + ServerInstance->Logs->Log("RESOLVER",DEBUG,"DNS::DNS"); + /* Clear the Resolver class table */ + memset(Classes,0,sizeof(Classes)); + + /* Clear the requests class table */ + memset(requests,0,sizeof(requests)); + + /* DNS::Rehash() sets this to a valid ptr + */ + this->cache = NULL; + + /* Again, DNS::Rehash() sets this to a + * valid value + */ + this->SetFd(-1); + + /* Actually read the settings + */ + this->Rehash(); + + this->PruneTimer = new CacheTimer(this); + + ServerInstance->Timers->AddTimer(this->PruneTimer); } -/* Build a payload to be placed after the header, based upon input data, a resource type, a class and a pointer to a buffer */ +/** Build a payload to be placed after the header, based upon input data, a resource type, a class and a pointer to a buffer */ int DNS::MakePayload(const char * const name, const QueryType rr, const unsigned short rr_class, unsigned char * const payload) { short payloadpos = 0; @@ -342,17 +448,17 @@ int DNS::MakePayload(const char * const name, const QueryType rr, const unsigned return payloadpos + 4; } -/* Start lookup of an hostname to an IP address */ +/** Start lookup of an hostname to an IP address */ int DNS::GetIP(const char *name) { DNSHeader h; int id; int length; - + if ((length = this->MakePayload(name, DNS_QUERY_A, 1, (unsigned char*)&h.payload)) == -1) return -1; - DNSRequest* req = this->AddQuery(&h, id); + DNSRequest* req = this->AddQuery(&h, id, name); if ((!req) || (req->SendRequests(&h, length, DNS_QUERY_A) == -1)) return -1; @@ -360,7 +466,7 @@ int DNS::GetIP(const char *name) return id; } -/* Start lookup of an hostname to an IPv6 address */ +/** Start lookup of an hostname to an IPv6 address */ int DNS::GetIP6(const char *name) { DNSHeader h; @@ -370,7 +476,7 @@ int DNS::GetIP6(const char *name) if ((length = this->MakePayload(name, DNS_QUERY_AAAA, 1, (unsigned char*)&h.payload)) == -1) return -1; - DNSRequest* req = this->AddQuery(&h, id); + DNSRequest* req = this->AddQuery(&h, id, name); if ((!req) || (req->SendRequests(&h, length, DNS_QUERY_AAAA) == -1)) return -1; @@ -378,7 +484,7 @@ int DNS::GetIP6(const char *name) return id; } -/* Start lookup of a cname to another name */ +/** Start lookup of a cname to another name */ int DNS::GetCName(const char *alias) { DNSHeader h; @@ -388,7 +494,7 @@ int DNS::GetCName(const char *alias) if ((length = this->MakePayload(alias, DNS_QUERY_CNAME, 1, (unsigned char*)&h.payload)) == -1) return -1; - DNSRequest* req = this->AddQuery(&h, id); + DNSRequest* req = this->AddQuery(&h, id, alias); if ((!req) || (req->SendRequests(&h, length, DNS_QUERY_CNAME) == -1)) return -1; @@ -396,34 +502,7 @@ int DNS::GetCName(const char *alias) return id; } -/* Start lookup of an IP address to a hostname */ -int DNS::GetName(const insp_inaddr *ip) -{ - char query[128]; - DNSHeader h; - int id; - int length; - -#ifdef IPV6 - DNS::MakeIP6Int(query, (in6_addr*)ip); -#else - unsigned char* c = (unsigned char*)&ip->s_addr; - - sprintf(query,"%d.%d.%d.%d.in-addr.arpa",c[3],c[2],c[1],c[0]); -#endif - - if ((length = this->MakePayload(query, DNS_QUERY_PTR, 1, (unsigned char*)&h.payload)) == -1) - return -1; - - DNSRequest* req = this->AddQuery(&h, id); - - if ((!req) || (req->SendRequests(&h, length, DNS_QUERY_PTR) == -1)) - return -1; - - return id; -} - -/* Start lookup of an IP address to a hostname */ +/** Start lookup of an IP address to a hostname */ int DNS::GetNameForce(const char *ip, ForceProtocol fp) { char query[128]; @@ -439,8 +518,11 @@ int DNS::GetNameForce(const char *ip, ForceProtocol fp) DNS::MakeIP6Int(query, &i); } else + { + ServerInstance->Logs->Log("RESOLVER",DEBUG,"DNS::GetNameForce IPv6 bad format for '%s'", ip); /* Invalid IP address */ return -1; + } } else { @@ -451,23 +533,39 @@ int DNS::GetNameForce(const char *ip, ForceProtocol fp) sprintf(query,"%d.%d.%d.%d.in-addr.arpa",c[3],c[2],c[1],c[0]); } else + { + ServerInstance->Logs->Log("RESOLVER",DEBUG,"DNS::GetNameForce IPv4 bad format for '%s'", ip); /* Invalid IP address */ return -1; + } } - log(DEBUG,"DNS::GetNameForce: %s %d",query, fp); - - if ((length = this->MakePayload(query, DNS_QUERY_PTR, 1, (unsigned char*)&h.payload)) == -1) + length = this->MakePayload(query, DNS_QUERY_PTR, 1, (unsigned char*)&h.payload); + if (length == -1) + { + ServerInstance->Logs->Log("RESOLVER",DEBUG,"DNS::GetNameForce can't query '%s' using '%s' because it's too long", ip, query); return -1; + } - DNSRequest* req = this->AddQuery(&h, id); + DNSRequest* req = this->AddQuery(&h, id, ip); - if ((!req) || (req->SendRequests(&h, length, DNS_QUERY_PTR) == -1)) + if (!req) + { + ServerInstance->Logs->Log("RESOLVER",DEBUG,"DNS::GetNameForce can't add query (resolver down?)"); return -1; + } + + if (req->SendRequests(&h, length, DNS_QUERY_PTR) == -1) + { + ServerInstance->Logs->Log("RESOLVER",DEBUG,"DNS::GetNameForce can't send (firewall?)"); + return -1; + } return id; } +/** Build an ipv6 reverse domain from an in6_addr + */ void DNS::MakeIP6Int(char* query, const in6_addr *ip) { const char* hex = "0123456789abcdef"; @@ -484,44 +582,44 @@ void DNS::MakeIP6Int(char* query, const in6_addr *ip) strcpy(query,"ip6.arpa"); /* Suffix the string */ } -/* Return the next id which is ready, and the result attached to it */ +/** Return the next id which is ready, and the result attached to it */ DNSResult DNS::GetResult() { /* Fetch dns query response and decide where it belongs */ DNSHeader header; DNSRequest *req; unsigned char buffer[sizeof(DNSHeader)]; - sockaddr from; + irc::sockets::sockaddrs from; + memset(&from, 0, sizeof(from)); socklen_t x = sizeof(from); - const char* ipaddr_from = ""; - unsigned short int port_from = 0; - int length = recvfrom(MasterSocket,buffer,sizeof(DNSHeader),0,&from,&x); + int length = ServerInstance->SE->RecvFrom(this, (char*)buffer, sizeof(DNSHeader), 0, &from.sa, &x); /* Did we get the whole header? */ if (length < 12) + { + ServerInstance->Logs->Log("RESOLVER",DEBUG,"GetResult didn't get a full packet (len=%d)", length); /* Nope - something screwed up. */ - return std::make_pair(-1,""); + return DNSResult(-1,"",0,""); + } /* Check wether the reply came from a different DNS * server to the one we sent it to, or the source-port * is not 53. * A user could in theory still spoof dns packets anyway * but this is less trivial than just sending garbage - * to the client, which is possible without this check. + * to the server, which is possible without this check. * * -- Thanks jilles for pointing this one out. */ -#ifdef IPV6 - ipaddr_from = insp_ntoa(((sockaddr_in6*)&from)->sin6_addr); - port_from = ntohs(((sockaddr_in6*)&from)->sin6_port); -#else - ipaddr_from = insp_ntoa(((sockaddr_in*)&from)->sin_addr); - port_from = ntohs(((sockaddr_in*)&from)->sin_port); -#endif - - if ((port_from != DNS::QUERY_PORT) || (strcasecmp(ipaddr_from, Config->DNSServer))) - return std::make_pair(-1,""); + if (from != myserver) + { + std::string server1 = from.str(); + std::string server2 = myserver.str(); + ServerInstance->Logs->Log("RESOLVER",DEBUG,"Got a result from the wrong server! Bad NAT or DNS forging attempt? '%s' != '%s'", + server1.c_str(), server2.c_str()); + return DNSResult(-1,"",0,""); + } /* Put the read header info into a header class */ DNS::FillHeader(&header,buffer,length - 12); @@ -533,18 +631,17 @@ DNSResult DNS::GetResult() unsigned long this_id = header.id[1] + (header.id[0] << 8); /* Do we have a pending request matching this id? */ - requestlist_iter n_iter = requests.find(this_id); - if (n_iter == requests.end()) + if (!requests[this_id]) { /* Somehow we got a DNS response for a request we never made... */ - log(DEBUG,"DNS: got a response for a query we didnt send with fd=%d queryid=%d",MasterSocket,this_id); - return std::make_pair(-1,""); + ServerInstance->Logs->Log("RESOLVER",DEBUG,"Hmm, got a result that we didn't ask for (id=%lx). Ignoring.", this_id); + return DNSResult(-1,"",0,""); } else { /* Remove the query from the list of pending queries */ - req = (DNSRequest*)n_iter->second; - requests.erase(n_iter); + req = requests[this_id]; + requests[this_id] = NULL; } /* Inform the DNSRequest class that it has a result to be read. @@ -563,11 +660,13 @@ DNSResult DNS::GetResult() * an error response and needs to be treated uniquely. * Put the error message in the second field. */ + std::string ro = req->orig; delete req; - return std::make_pair(this_id | ERROR_MASK, data.second); + return DNSResult(this_id | ERROR_MASK, data.second, 0, ro); } else { + unsigned long ttl = req->ttl; char formatted[128]; /* Forward lookups come back as binary data. We must format them into ascii */ @@ -580,28 +679,22 @@ DNSResult DNS::GetResult() case DNS_QUERY_AAAA: { - snprintf(formatted,40,"%x:%x:%x:%x:%x:%x:%x:%x", - (ntohs(data.first[0]) + ntohs(data.first[1] << 8)), - (ntohs(data.first[2]) + ntohs(data.first[3] << 8)), - (ntohs(data.first[4]) + ntohs(data.first[5] << 8)), - (ntohs(data.first[6]) + ntohs(data.first[7] << 8)), - (ntohs(data.first[8]) + ntohs(data.first[9] << 8)), - (ntohs(data.first[10]) + ntohs(data.first[11] << 8)), - (ntohs(data.first[12]) + ntohs(data.first[13] << 8)), - (ntohs(data.first[14]) + ntohs(data.first[15] << 8))); - char* c = strstr(formatted,":0:"); - if (c != NULL) + if (!inet_ntop(AF_INET6, data.first, formatted, sizeof(formatted))) { - memmove(c+1,c+2,strlen(c+2) + 1); - c += 2; - while (memcmp(c,"0:",2) == 0) - memmove(c,c+2,strlen(c+2) + 1); - if (memcmp(c,"0",2) == 0) - *c = 0; - if (memcmp(formatted,"0::",3) == 0) - memmove(formatted,formatted + 1, strlen(formatted + 1) + 1); + std::string ro = req->orig; + delete req; + return DNSResult(this_id | ERROR_MASK, "inet_ntop() failed", 0, ro); } + resultstr = formatted; + + /* Special case. Sending ::1 around between servers + * and to clients is dangerous, because the : on the + * start makes the client or server interpret the IP + * as the last parameter on the line with a value ":1". + */ + if (*formatted == ':') + resultstr.insert(0, "0"); } break; @@ -609,31 +702,45 @@ DNSResult DNS::GetResult() /* Identical handling to PTR */ case DNS_QUERY_PTR: + { /* Reverse lookups just come back as char* */ resultstr = std::string((const char*)data.first); + if (resultstr.find_first_not_of("0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ.-") != std::string::npos) + { + std::string ro = req->orig; + delete req; + return DNSResult(this_id | ERROR_MASK, "Invalid char(s) in reply", 0, ro); + } + } break; default: - log(DEBUG,"WARNING: Somehow we made a request for a DNS_QUERY_PTR4 or DNS_QUERY_PTR6, but these arent real rr types!"); break; - } /* Build the reply with the id and hostname/ip in it */ + std::string ro = req->orig; + DNSResult result = DNSResult(this_id,resultstr,ttl,ro,req->type); delete req; - return std::make_pair(this_id,resultstr); + return result; } } -/* A result is ready, process it */ -DNSInfo DNSRequest::ResultIsReady(DNSHeader &header, int length) +/** A result is ready, process it */ +DNSInfo DNSRequest::ResultIsReady(DNSHeader &header, unsigned length) { - int i = 0; + unsigned i = 0, o; int q = 0; - int curanswer, o; + int curanswer; ResourceRecord rr; unsigned short ptr; - + + /* This is just to keep _FORTIFY_SOURCE happy */ + rr.type = DNS_QUERY_NONE; + rr.rdlength = 0; + rr.ttl = 1; /* GCC is a whiney bastard -- see the XXX below. */ + rr.rr_class = 0; /* Same for VC++ */ + if (!(header.flags1 & FLAGS_MASK_QR)) return std::make_pair((unsigned char*)NULL,"Not a query result"); @@ -687,11 +794,14 @@ DNSInfo DNSRequest::ResultIsReady(DNSHeader &header, int length) else i += header.payload[i] + 1; /* skip length and label */ } } - if (length - i < 10) + if (static_cast(length - i) < 10) return std::make_pair((unsigned char*)NULL,"Incorrectly sized DNS reply"); + /* XXX: We actually initialise 'rr' here including its ttl field */ DNS::FillResourceRecord(&rr,&header.payload[i]); + i += 10; + ServerInstance->Logs->Log("RESOLVER",DEBUG,"Resolver: rr.type is %d and this.type is %d rr.class %d this.class %d", rr.type, this->type, rr.rr_class, this->rr_class); if (rr.type != this->type) { curanswer++; @@ -707,7 +817,7 @@ DNSInfo DNSRequest::ResultIsReady(DNSHeader &header, int length) break; } if ((unsigned int)curanswer == header.ancount) - return std::make_pair((unsigned char*)NULL,"No valid answers"); + return std::make_pair((unsigned char*)NULL,"No A, AAAA or PTR type answers (" + ConvToStr(header.ancount) + " answers)"); if (i + rr.rdlength > (unsigned int)length) return std::make_pair((unsigned char*)NULL,"Resource record larger than stated"); @@ -715,19 +825,41 @@ DNSInfo DNSRequest::ResultIsReady(DNSHeader &header, int length) if (rr.rdlength > 1023) return std::make_pair((unsigned char*)NULL,"Resource record too large"); + this->ttl = rr.ttl; + switch (rr.type) { + /* + * CNAME and PTR are compressed. We need to decompress them. + */ case DNS_QUERY_CNAME: - /* CNAME and PTR have the same processing code */ case DNS_QUERY_PTR: + { + unsigned short lowest_pos = length; o = 0; q = 0; while (q == 0 && i < length && o + 256 < 1023) { + /* DN label found (byte over 63) */ if (header.payload[i] > 63) { memcpy(&ptr,&header.payload[i],2); - i = ntohs(ptr) - 0xC000 - 12; + + i = ntohs(ptr); + + /* check that highest two bits are set. if not, we've been had */ + if ((i & DN_COMP_BITMASK) != DN_COMP_BITMASK) + return std::make_pair((unsigned char *) NULL, "DN label decompression header is bogus"); + + /* mask away the two highest bits. */ + i &= ~DN_COMP_BITMASK; + + /* and decrease length by 12 bytes. */ + i -= 12; + + if (i >= lowest_pos) + return std::make_pair((unsigned char *) NULL, "Invalid decompression pointer"); + lowest_pos = i; } else { @@ -740,41 +872,91 @@ DNSInfo DNSRequest::ResultIsReady(DNSHeader &header, int length) res[o] = 0; if (o != 0) res[o++] = '.'; - memcpy(&res[o],&header.payload[i + 1],header.payload[i]); + + if (o + header.payload[i] > sizeof(DNSHeader)) + return std::make_pair((unsigned char *) NULL, "DN label decompression is impossible -- malformed/hostile packet?"); + + memcpy(&res[o], &header.payload[i + 1], header.payload[i]); o += header.payload[i]; i += header.payload[i] + 1; } } } res[o] = 0; + } break; case DNS_QUERY_AAAA: + if (rr.rdlength != sizeof(struct in6_addr)) + return std::make_pair((unsigned char *) NULL, "rr.rdlength is larger than 16 bytes for an ipv6 entry -- malformed/hostile packet?"); + memcpy(res,&header.payload[i],rr.rdlength); res[rr.rdlength] = 0; break; case DNS_QUERY_A: + if (rr.rdlength != sizeof(struct in_addr)) + return std::make_pair((unsigned char *) NULL, "rr.rdlength is larger than 4 bytes for an ipv4 entry -- malformed/hostile packet?"); + memcpy(res,&header.payload[i],rr.rdlength); res[rr.rdlength] = 0; break; default: - memcpy(res,&header.payload[i],rr.rdlength); - res[rr.rdlength] = 0; + return std::make_pair((unsigned char *) NULL, "don't know how to handle undefined type (" + ConvToStr(rr.type) + ") -- rejecting"); break; } - return std::make_pair(res,"No error");; + return std::make_pair(res,"No error"); } -/* Close the master socket */ +/** Close the master socket */ DNS::~DNS() { - shutdown(MasterSocket, 2); - close(MasterSocket); + ServerInstance->SE->Shutdown(this, 2); + ServerInstance->SE->Close(this); + ServerInstance->Timers->DelTimer(this->PruneTimer); + if (cache) + delete cache; +} + +CachedQuery* DNS::GetCache(const std::string &source) +{ + dnscache::iterator x = cache->find(source.c_str()); + if (x != cache->end()) + return &(x->second); + else + return NULL; +} + +void DNS::DelCache(const std::string &source) +{ + cache->erase(source.c_str()); } -/* High level abstraction of dns used by application at large */ -Resolver::Resolver(const std::string &source, QueryType qt) : input(source), querytype(qt) +void Resolver::TriggerCachedResult() { - insp_inaddr binip; + if (CQ) + OnLookupComplete(CQ->data, time_left, true); +} + +/** High level abstraction of dns used by application at large */ +Resolver::Resolver(const std::string &source, QueryType qt, bool &cached, Module* creator) : Creator(creator), input(source), querytype(qt) +{ + ServerInstance->Logs->Log("RESOLVER",DEBUG,"Resolver::Resolver"); + cached = false; + + CQ = ServerInstance->Res->GetCache(source); + if (CQ) + { + time_left = CQ->CalcTTLRemaining(); + if (!time_left) + { + ServerInstance->Res->DelCache(source); + } + else if (CQ->type == qt) + { + cached = true; + return; + } + CQ = NULL; + } switch (querytype) { @@ -782,20 +964,6 @@ Resolver::Resolver(const std::string &source, QueryType qt) : input(source), que this->myid = ServerInstance->Res->GetIP(source.c_str()); break; - case DNS_QUERY_PTR: - if (insp_aton(source.c_str(), &binip) > 0) - { - /* Valid ip address */ - this->myid = ServerInstance->Res->GetName(&binip); - } - else - { - this->OnError(RESOLVER_BADIP, "Bad IP address for reverse lookup"); - throw ModuleException("Resolver: Bad IP address"); - return; - } - break; - case DNS_QUERY_PTR4: querytype = DNS_QUERY_PTR; this->myid = ServerInstance->Res->GetNameForce(source.c_str(), PROTOCOL_IPV4); @@ -815,90 +983,104 @@ Resolver::Resolver(const std::string &source, QueryType qt) : input(source), que break; default: + ServerInstance->Logs->Log("RESOLVER",DEBUG,"DNS request with unknown query type %d", querytype); this->myid = -1; break; } if (this->myid == -1) { - log(DEBUG,"Resolver::Resolver: Could not get an id!"); - this->OnError(RESOLVER_NSDOWN, "Nameserver is down"); - throw ModuleException("Resolver: Couldnt get an id to make a request"); - /* We shouldnt get here really */ - return; + throw ModuleException("Resolver: Couldn't get an id to make a request"); + } + else + { + ServerInstance->Logs->Log("RESOLVER",DEBUG,"DNS request id %d", this->myid); } - - log(DEBUG,"Resolver::Resolver: this->myid=%d",this->myid); } -void Resolver::OnError(ResolverError e, const std::string &errormessage) +/** Called when an error occurs */ +void Resolver::OnError(ResolverError, const std::string&) { /* Nothing in here */ } +/** Destroy a resolver */ Resolver::~Resolver() { /* Nothing here (yet) either */ } -/* Get the request id associated with this class */ +/** Get the request id associated with this class */ int Resolver::GetId() { return this->myid; } -/* Process a socket read event */ -void DNS::MarshallReads(int fd) +Module* Resolver::GetCreator() +{ + return this->Creator; +} + +/** Process a socket read event */ +void DNS::HandleEvent(EventType, int) { - /* We are only intrested in our single fd */ - if (fd == GetMasterSocket()) + /* Fetch the id and result of the next available packet */ + DNSResult res(0,"",0,""); + res.id = 0; + ServerInstance->Logs->Log("RESOLVER",DEBUG,"Handle DNS event"); + + res = this->GetResult(); + + ServerInstance->Logs->Log("RESOLVER",DEBUG,"Result id %d", res.id); + + /* Is there a usable request id? */ + if (res.id != -1) { - /* Fetch the id and result of the next available packet */ - DNSResult res = this->GetResult(); - /* Is there a usable request id? */ - if (res.first != -1) + /* Its an error reply */ + if (res.id & ERROR_MASK) { - /* Its an error reply */ - if (res.first & ERROR_MASK) + /* Mask off the error bit */ + res.id -= ERROR_MASK; + /* Marshall the error to the correct class */ + if (Classes[res.id]) { - /* Mask off the error bit */ - res.first -= ERROR_MASK; - - /* Marshall the error to the correct class */ - log(DEBUG,"Error available, id=%d",res.first); - if (Classes[res.first]) - { - if (ServerInstance && ServerInstance->stats) - ServerInstance->stats->statsDnsBad++; - Classes[res.first]->OnError(RESOLVER_NXDOMAIN, res.second); - delete Classes[res.first]; - Classes[res.first] = NULL; - } + if (ServerInstance && ServerInstance->stats) + ServerInstance->stats->statsDnsBad++; + Classes[res.id]->OnError(RESOLVER_NXDOMAIN, res.result); + delete Classes[res.id]; + Classes[res.id] = NULL; } - else + return; + } + else + { + /* It is a non-error result, marshall the result to the correct class */ + if (Classes[res.id]) { - /* It is a non-error result */ - log(DEBUG,"Result available, id=%d",res.first); - /* Marshall the result to the correct class */ - if (Classes[res.first]) + if (ServerInstance && ServerInstance->stats) + ServerInstance->stats->statsDnsGood++; + + if (!this->GetCache(res.original.c_str())) { - if (ServerInstance && ServerInstance->stats) - ServerInstance->stats->statsDnsGood++; - Classes[res.first]->OnLookupComplete(res.second); - delete Classes[res.first]; - Classes[res.first] = NULL; + if (cache->size() >= MAX_CACHE_SIZE) + cache->clear(); + this->cache->insert(std::make_pair(res.original.c_str(), CachedQuery(res.result, res.type, res.ttl))); } - } - - if (ServerInstance && ServerInstance->stats) - ServerInstance->stats->statsDns++; + Classes[res.id]->OnLookupComplete(res.result, res.ttl, false); + delete Classes[res.id]; + Classes[res.id] = NULL; + } } + + if (ServerInstance && ServerInstance->stats) + ServerInstance->stats->statsDns++; } } -/* Add a derived Resolver to the working set */ +/** Add a derived Resolver to the working set */ bool DNS::AddResolverClass(Resolver* r) { + ServerInstance->Logs->Log("RESOLVER",DEBUG,"AddResolverClass 0x%08lx", (unsigned long)r); /* Check the pointers validity and the id's validity */ if ((r) && (r->GetId() > -1)) { @@ -912,31 +1094,27 @@ bool DNS::AddResolverClass(Resolver* r) Classes[r->GetId()] = r; return true; } - else - /* Duplicate id */ - return false; } - else - { - /* Pointer or id not valid. - * Free the item and return - */ - if (r) - delete r; - return false; - } + /* Pointer or id not valid, or duplicate id. + * Free the item and return + */ + delete r; + return false; } -unsigned long DNS::PRNG() +void DNS::CleanResolvers(Module* module) { - unsigned long val = 0; - timeval n; - serverstats* s = ServerInstance->stats; - gettimeofday(&n,NULL); - val = (n.tv_usec ^ getpid() ^ geteuid() ^ (this->currid++)) ^ s->statsAccept + n.tv_sec; - val = val + s->statsCollisions ^ s->statsDnsGood - s->statsDnsBad; - val += (s->statsConnects ^ (unsigned long)s->statsSent ^ (unsigned long)s->statsRecv) - s->BoundPortCount; - return val; + for (int i = 0; i < MAX_REQUEST_ID; i++) + { + if (Classes[i]) + { + if (Classes[i]->GetCreator() == module) + { + Classes[i]->OnError(RESOLVER_FORCEUNLOAD, "Parent module is unloading"); + delete Classes[i]; + Classes[i] = NULL; + } + } + } } -