X-Git-Url: https://git.netwichtig.de/gitweb/?a=blobdiff_plain;f=src%2Fdns.cpp;h=ea6b000a9e3d788373b571feb731475fdffa29e7;hb=09c716ce117e3c89b4da7ab88f4caaefb43511b5;hp=e0cb3ccaa77630a8fdb899217feea6323589b60e;hpb=ce9d870efaab76a3a4d5d64c4c873b43c7b831a3;p=user%2Fhenk%2Fcode%2Finspircd.git diff --git a/src/dns.cpp b/src/dns.cpp index e0cb3ccaa..3d3bc947f 100644 --- a/src/dns.cpp +++ b/src/dns.cpp @@ -1,146 +1,208 @@ -/* +------------------------------------+ - * | 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 + * + * 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. * - * 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 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 loosely based on the firedns library, -Copyright (C) 2002 Ian Gulliver. - -There have been so many modifications to this file -to make it fit into InspIRCd and make it object -orientated that you should not take this code as -being what firedns really looks like. It used to -look very different to this! :-P +Very very loosely based on the firedns library, +Copyright (C) 2002 Ian Gulliver. This file is no +longer anything like firedns, there are many major +differences between this code and the original. +Please do not assume that firedns works like this, +looks like this, walks like this or tastes like this. */ -using namespace std; - -#include -#include -#include +#ifndef _WIN32 #include #include -#include -#include -#include -#include #include -#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" -extern InspIRCd* ServerInstance; -extern ServerConfig* Config; -extern time_t TIME; -extern userrec* fd_ref_table[MAX_DESCRIPTORS]; - -enum QueryType { DNS_QRY_A = 1, DNS_QRY_PTR = 12 }; -enum QueryFlags1 { FLAGS1_MASK_RD = 0x01, FLAGS1_MASK_TC = 0x02, FLAGS1_MASK_AA = 0x04, FLAGS1_MASK_OPCODE = 0x78, FLAGS1_MASK_QR = 0x80 }; -enum QueryFlags2 { FLAGS2_MASK_RCODE = 0x0F, FLAGS2_MASK_Z = 0x70, FLAGS2_MASK_RA = 0x80 }; - -class s_connection; +#define DN_COMP_BITMASK 0xC000 /* highest 6 bits in a DN label header */ -typedef std::map connlist; -typedef connlist::iterator connlist_iter; +/** Masks to mask off the responses we get from the DNSRequest methods + */ +enum QueryInfo +{ + ERROR_MASK = 0x10000 /* Result is an error */ +}; -DNS* Res = NULL; +/** Flags which can be ORed into a request or reply for different meanings + */ +enum QueryFlags +{ + FLAGS_MASK_RD = 0x01, /* Recursive */ + FLAGS_MASK_TC = 0x02, + FLAGS_MASK_AA = 0x04, /* Authoritative */ + FLAGS_MASK_OPCODE = 0x78, + FLAGS_MASK_QR = 0x80, + FLAGS_MASK_RCODE = 0x0F, /* Request */ + FLAGS_MASK_Z = 0x70, + FLAGS_MASK_RA = 0x80 +}; -connlist connections; -int master_socket = -1; -Resolver* dns_classes[65536]; -insp_inaddr myserver; -class s_rr_middle +/** Represents a dns resource record (rr) + */ +struct ResourceRecord { - public: - QueryType type; - unsigned int _class; - unsigned long ttl; - unsigned int rdlength; + QueryType type; /* Record type */ + unsigned int rr_class; /* Record class */ + unsigned long ttl; /* Time to live */ + unsigned int rdlength; /* Record length */ }; -class s_header +/** Represents a dns request/reply header, and its payload as opaque data. + */ +class DNSHeader { public: - unsigned char id[2]; - unsigned int flags1; - unsigned int flags2; + unsigned char id[2]; /* Request id */ + unsigned int flags1; /* Flags */ + unsigned int flags2; /* Flags */ unsigned int qdcount; - unsigned int ancount; - unsigned int nscount; + unsigned int ancount; /* Answer count */ + unsigned int nscount; /* Nameserver count */ unsigned int arcount; - unsigned char payload[512]; + unsigned char payload[512]; /* Packet payload */ +}; + +class DNSRequest +{ + public: + unsigned char id[2]; /* Request id */ + unsigned char* res; /* Result processing buffer */ + unsigned int rr_class; /* Request class */ + QueryType type; /* Request type */ + 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 s_connection +class CacheTimer : public Timer { + private: + DNS* dns; public: - unsigned char id[2]; - unsigned char res[512]; - unsigned int _class; - QueryType type; + CacheTimer(DNS* thisdns) + : Timer(5*60, ServerInstance->Time(), true), dns(thisdns) { } - s_connection() + virtual void Tick(time_t) { - *res = 0; + dns->PruneCache(); } +}; - unsigned char* result_ready(s_header &h, int length); - int send_requests(const s_header *h, const int l); +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) + { + } + ~RequestTimeout() + { + if (ServerInstance->Res) + Tick(0); + } + + 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; + } + } }; +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); +} -void *dns_align(void *inp) +/* Allocate the processing buffer */ +DNSRequest::DNSRequest(DNS* dns, int rid, const std::string &original) : dnsobj(dns) { - char *p = (char*)inp; - int offby = ((char *)p - (char *)0) % (sizeof(void *) > sizeof(long) ? sizeof(void *) : sizeof(long)); - if (offby != 0) - return p + ((sizeof(void *) > sizeof(long) ? sizeof(void *) : sizeof(long)) - offby); - else - return p; + /* 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 */ } -/* - * Optimized by brain, these were using integer division and modulus. - * We can use logic shifts and logic AND to replace these even divisions - * and multiplications, it should be a bit faster (probably not noticably, - * but of course, more impressive). Also made these inline. - */ +/* Deallocate the processing buffer */ +DNSRequest::~DNSRequest() +{ + delete[] res; +} -inline void dns_fill_rr(s_rr_middle* rr, const unsigned char *input) +/** 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]); - rr->_class = (input[2] << 8) + input[3]; + rr->rr_class = (input[2] << 8) + input[3]; rr->ttl = (input[4] << 24) + (input[5] << 16) + (input[6] << 8) + input[7]; rr->rdlength = (input[8] << 8) + input[9]; } -inline void dns_fill_header(s_header *header, const unsigned char *input, const int l) +/** 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]; header->id[1] = input[1]; @@ -150,10 +212,11 @@ inline void dns_fill_header(s_header *header, const unsigned char *input, const header->ancount = (input[6] << 8) + input[7]; header->nscount = (input[8] << 8) + input[9]; header->arcount = (input[10] << 8) + input[11]; - memcpy(header->payload,&input[12],l); + memcpy(header->payload,&input[12],length); } -inline void dns_empty_header(unsigned char *output, const s_header *header, const int l) +/** 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]; output[1] = header->id[1]; @@ -167,344 +230,585 @@ inline void dns_empty_header(unsigned char *output, const s_header *header, cons output[9] = header->nscount & 0xFF; output[10] = header->arcount >> 8; output[11] = header->arcount & 0xFF; - memcpy(&output[12],header->payload,l); + memcpy(&output[12],header->payload,length); } - -int s_connection::send_requests(const s_header *h, const int l) +/** Send requests we have previously built down the UDP socket */ +int DNSRequest::SendRequests(const DNSHeader *header, const int length, QueryType qt) { - insp_sockaddr addr; - unsigned char payload[sizeof(s_header)]; + ServerInstance->Logs->Log("RESOLVER", DEBUG,"DNSRequest::SendRequests"); - dns_empty_header(payload,h,l); + unsigned char payload[sizeof(DNSHeader)]; - 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(53); -#else - memcpy(&addr.sin_addr.s_addr,&myserver,sizeof(addr.sin_addr)); - addr.sin_family = AF_FAMILY; - addr.sin_port = htons(53); -#endif - if (sendto(master_socket, payload, l + 12, 0, (sockaddr *) &addr, sizeof(addr)) == -1) - { - log(DEBUG,"Error in sendto!"); + this->rr_class = 1; + this->type = qt; + + DNS::EmptyHeader(payload,header,length); + + 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; } -s_connection* dns_add_query(s_header *h, 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) { + /* Is the DNS connection down? */ + if (this->GetFd() == -1) + return NULL; - id = rand() % 65536; - s_connection * s = new s_connection(); + /* Create an 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; + } + } - h->id[0] = s->id[0] = id >> 8; - h->id[1] = s->id[1] = id & 0xFF; - h->flags1 = 0 | FLAGS1_MASK_RD; - h->flags2 = 0; - h->qdcount = 1; - h->ancount = 0; - h->nscount = 0; - h->arcount = 0; + if (id == -1) + throw ModuleException("DNS: All ids are in use"); + + 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; + header->flags1 = FLAGS_MASK_RD; + header->flags2 = 0; + header->qdcount = 1; + header->ancount = 0; + header->nscount = 0; + header->arcount = 0; + + /* At this point we already know the id doesnt exist, + * so there needs to be no second check for the ::end() + */ + requests[id] = req; + + /* According to the C++ spec, new never returns NULL. */ + return req; +} - if (connections.find(id) == connections.end()) - connections[id] = s; - return s; +int DNS::ClearCache() +{ + /* This ensures the buckets are reset to sane levels */ + int rv = this->cache->size(); + delete this->cache; + this->cache = new dnscache(); + return rv; } -void create_socket() +int DNS::PruneCache() { - log(DEBUG,"---- BEGIN DNS INITIALIZATION, SERVER=%s ---",Config->DNSServer); - insp_inaddr addr; - srand((unsigned int) TIME); - memset(&myserver,0,sizeof(insp_inaddr)); - if (insp_aton(Config->DNSServer,&addr) > 0) - memcpy(&myserver,&addr,sizeof(insp_inaddr)); + 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++; - master_socket = socket(PF_PROTOCOL, SOCK_DGRAM, 0); - if (master_socket != -1) + delete this->cache; + this->cache = newcache; + return n; +} + +void DNS::Rehash() +{ + if (this->GetFd() > -1) { - log(DEBUG,"Set query socket nonblock"); - if (fcntl(master_socket, F_SETFL, O_NONBLOCK) != 0) - { - shutdown(master_socket,2); - close(master_socket); - master_socket = -1; - } + ServerInstance->SE->DelFd(this); + ServerInstance->SE->Shutdown(this, 2); + ServerInstance->SE->Close(this); + this->SetFd(-1); + + /* Rehash the cache */ + this->PruneCache(); + } + else + { + /* Create initial dns cache */ + this->cache = new dnscache(); } - if (master_socket != -1) + + irc::sockets::aptosa(ServerInstance->Config->DNSServer, DNS::QUERY_PORT, myserver); + + /* Initialize mastersocket */ + int s = socket(myserver.sa.sa_family, SOCK_DGRAM, 0); + this->SetFd(s); + + /* Have we got a socket and is it nonblocking? */ + if (this->GetFd() != -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 - log(DEBUG,"Binding query port"); - if (bind(master_socket,(sockaddr *)&addr,sizeof(addr)) != 0) + 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) { - log(DEBUG,"Cant bind with source port = 0"); - shutdown(master_socket,2); - close(master_socket); - master_socket = -1; + /* Failed to bind */ + 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 (master_socket >= 0) + else if (!ServerInstance->SE->AddFd(this, FD_WANT_POLL_READ | FD_WANT_NO_WRITE)) { - log(DEBUG,"Attach query port to socket engine"); - if (ServerInstance && ServerInstance->SE) - ServerInstance->SE->AddFd(master_socket,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"); + } } -int dns_build_query_payload(const char * const name, const unsigned short rr, const unsigned short _class, unsigned char * const payload) +/** Initialise the DNS UDP socket so that we can send requests */ +DNS::DNS() { - short payloadpos; - const char * tempchr, * tempchr2; - unsigned short l; + 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); +} - payloadpos = 0; - tempchr2 = name; +/** 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; + const char* tempchr, *tempchr2 = name; + unsigned short length; /* split name up into labels, create query */ while ((tempchr = strchr(tempchr2,'.')) != NULL) { - l = tempchr - tempchr2; - if (payloadpos + l + 1 > 507) + length = tempchr - tempchr2; + if (payloadpos + length + 1 > 507) return -1; - payload[payloadpos++] = l; - memcpy(&payload[payloadpos],tempchr2,l); - payloadpos += l; + payload[payloadpos++] = length; + memcpy(&payload[payloadpos],tempchr2,length); + payloadpos += length; tempchr2 = &tempchr[1]; } - l = strlen(tempchr2); - if (l) + length = strlen(tempchr2); + if (length) { - if (payloadpos + l + 2 > 507) + if (payloadpos + length + 2 > 507) return -1; - payload[payloadpos++] = l; - memcpy(&payload[payloadpos],tempchr2,l); - payloadpos += l; - payload[payloadpos++] = '\0'; + payload[payloadpos++] = length; + memcpy(&payload[payloadpos],tempchr2,length); + payloadpos += length; + payload[payloadpos++] = 0; } if (payloadpos > 508) return -1; - l = htons(rr); - memcpy(&payload[payloadpos],&l,2); - l = htons(_class); - memcpy(&payload[payloadpos + 2],&l,2); + length = htons(rr); + memcpy(&payload[payloadpos],&length,2); + length = htons(rr_class); + memcpy(&payload[payloadpos + 2],&length,2); return payloadpos + 4; } -int DNS::dns_getip4(const char *name) +/** Start lookup of an hostname to an IP address */ +int DNS::GetIP(const char *name) { - /* build, add and send A query; retrieve result with dns_getresult() */ - s_header h; - s_connection *s; - int l; + DNSHeader h; int id; - - l = dns_build_query_payload(name,DNS_QRY_A,1,(unsigned char *)&h.payload); - if (l == -1) - return -1; - s = dns_add_query(&h, id); - if (s == NULL) + int length; + + if ((length = this->MakePayload(name, DNS_QUERY_A, 1, (unsigned char*)&h.payload)) == -1) return -1; - s->_class = 1; - s->type = DNS_QRY_A; - if (s->send_requests(&h,l) == -1) + + DNSRequest* req = this->AddQuery(&h, id, name); + + if ((!req) || (req->SendRequests(&h, length, DNS_QUERY_A) == -1)) return -1; return id; } -int DNS::dns_getname4(const insp_inaddr *ip) -{ /* build, add and send PTR query; retrieve result with dns_getresult() */ -#ifdef IPV6 - return -1; -#else - log(DEBUG,"DNS::dns_getname4"); - char query[512]; - s_header h; - s_connection * s; - unsigned char *c; - int l; +/** Start lookup of an hostname to an IPv6 address */ +int DNS::GetIP6(const char *name) +{ + DNSHeader h; int id; + int length; - c = (unsigned char *)&ip->s_addr; + if ((length = this->MakePayload(name, DNS_QUERY_AAAA, 1, (unsigned char*)&h.payload)) == -1) + return -1; - sprintf(query,"%d.%d.%d.%d.in-addr.arpa",c[3],c[2],c[1],c[0]); + DNSRequest* req = this->AddQuery(&h, id, name); - l = dns_build_query_payload(query,DNS_QRY_PTR,1,(unsigned char *)&h.payload); - if (l == -1) - return -1; - s = dns_add_query(&h, id); - if (s == NULL) - return -1; - s->_class = 1; - s->type = DNS_QRY_PTR; - if (s->send_requests(&h,l) == -1) + if ((!req) || (req->SendRequests(&h, length, DNS_QUERY_AAAA) == -1)) return -1; return id; -#endif } -/* Return the next id which is ready, and the result attached to it - */ -DNSResult DNS::dns_getresult() +/** Start lookup of a cname to another name */ +int DNS::GetCName(const char *alias) { - /* retrieve result of DNS query (buffered) */ - s_header h; - s_connection *c; + DNSHeader h; + int id; int length; - unsigned char buffer[sizeof(s_header)]; - length = recv(master_socket,buffer,sizeof(s_header),0); + if ((length = this->MakePayload(alias, DNS_QUERY_CNAME, 1, (unsigned char*)&h.payload)) == -1) + return -1; - if (length < 12) - return std::make_pair(-1,""); - - dns_fill_header(&h,buffer,length - 12); - - // Get the id of this request - unsigned long this_id = h.id[1] + (h.id[0] << 8); - - // Do we have a pending request for it? - - connlist_iter n_iter = connections.find(this_id); - if (n_iter == connections.end()) - { - log(DEBUG,"DNS: got a response for a query we didnt send with fd=%d queryid=%d",master_socket,this_id); - return std::make_pair(-1,""); - } - else - { - /* Remove the query from the list */ - c = (s_connection*)n_iter->second; - /* We don't delete c here, because its done later when needed */ - connections.erase(n_iter); - } - unsigned char* a = c->result_ready(h, length); - std::string resultstr; + DNSRequest* req = this->AddQuery(&h, id, alias); - if (a == NULL) + if ((!req) || (req->SendRequests(&h, length, DNS_QUERY_CNAME) == -1)) + return -1; + + return id; +} + +/** Start lookup of an IP address to a hostname */ +int DNS::GetNameForce(const char *ip, ForceProtocol fp) +{ + char query[128]; + DNSHeader h; + int id; + int length; + + if (fp == PROTOCOL_IPV6) { - resultstr = ""; + in6_addr i; + if (inet_pton(AF_INET6, ip, &i) > 0) + { + DNS::MakeIP6Int(query, &i); + } + else + { + ServerInstance->Logs->Log("RESOLVER",DEBUG,"DNS::GetNameForce IPv6 bad format for '%s'", ip); + /* Invalid IP address */ + return -1; + } } else { - if (c->type == DNS_QRY_A) + in_addr i; + if (inet_aton(ip, &i)) { - char formatted[1024]; - snprintf(formatted,1024,"%u.%u.%u.%u",a[0],a[1],a[2],a[3]); - resultstr = std::string(formatted); + unsigned char* c = (unsigned char*)&i.s_addr; + sprintf(query,"%d.%d.%d.%d.in-addr.arpa",c[3],c[2],c[1],c[0]); } else { - resultstr = std::string((const char*)a); + ServerInstance->Logs->Log("RESOLVER",DEBUG,"DNS::GetNameForce IPv4 bad format for '%s'", ip); + /* Invalid IP address */ + return -1; } } - delete c; - return std::make_pair(this_id,resultstr); + 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, ip); + + 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; } -/** A result is ready, process it +/** Build an ipv6 reverse domain from an in6_addr */ -unsigned char* s_connection::result_ready(s_header &h, int length) +void DNS::MakeIP6Int(char* query, const in6_addr *ip) { - int i, q, curanswer, o; - s_rr_middle rr; - unsigned short p; - - if ((h.flags1 & FLAGS1_MASK_QR) == 0) + const char* hex = "0123456789abcdef"; + for (int index = 31; index >= 0; index--) /* for() loop steps twice per byte */ { - log(DEBUG,"DNS: didnt get a query result"); - return NULL; + if (index % 2) + /* low nibble */ + *query++ = hex[ip->s6_addr[index / 2] & 0x0F]; + else + /* high nibble */ + *query++ = hex[(ip->s6_addr[index / 2] & 0xF0) >> 4]; + *query++ = '.'; /* Seperator */ } - if ((h.flags1 & FLAGS1_MASK_OPCODE) != 0) + strcpy(query,"ip6.arpa"); /* Suffix the string */ +} + +/** 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)]; + irc::sockets::sockaddrs from; + memset(&from, 0, sizeof(from)); + socklen_t x = sizeof(from); + + int length = ServerInstance->SE->RecvFrom(this, (char*)buffer, sizeof(DNSHeader), 0, &from.sa, &x); + + /* Did we get the whole header? */ + if (length < 12) { - log(DEBUG,"DNS: got an OPCODE and didnt want one"); - return NULL; + ServerInstance->Logs->Log("RESOLVER",DEBUG,"GetResult didn't get a full packet (len=%d)", length); + /* Nope - something screwed up. */ + return DNSResult(-1,"",0,""); } - if ((h.flags2 & FLAGS2_MASK_RCODE) != 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 server, which is possible without this check. + * + * -- Thanks jilles for pointing this one out. + */ + if (from != myserver) { - log(DEBUG,"DNS lookup failed due to SERVFAIL"); - return NULL; + 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); + + /* Get the id of this request. + * Its a 16 bit value stored in two char's, + * so we use logic shifts to create the value. + */ + unsigned long this_id = header.id[1] + (header.id[0] << 8); + + /* Do we have a pending request matching this id? */ + if (!requests[this_id]) + { + /* Somehow we got a DNS response for a request we never made... */ + ServerInstance->Logs->Log("RESOLVER",DEBUG,"Hmm, got a result that we didn't ask for (id=%lx). Ignoring.", this_id); + return DNSResult(-1,"",0,""); } - if (h.ancount < 1) + else { - log(DEBUG,"DNS: no answers!"); - return NULL; + /* Remove the query from the list of pending queries */ + req = requests[this_id]; + requests[this_id] = NULL; } - i = 0; - q = 0; + + /* Inform the DNSRequest class that it has a result to be read. + * When its finished it will return a DNSInfo which is a pair of + * unsigned char* resource record data, and an error message. + */ + DNSInfo data = req->ResultIsReady(header, length); + std::string resultstr; + + /* Check if we got a result, if we didnt, its an error */ + if (data.first == NULL) + { + /* An error. + * Mask the ID with the value of ERROR_MASK, so that + * the dns_deal_with_classes() function knows that its + * 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 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 */ + switch (req->type) + { + case DNS_QUERY_A: + snprintf(formatted,16,"%u.%u.%u.%u",data.first[0],data.first[1],data.first[2],data.first[3]); + resultstr = formatted; + break; + + case DNS_QUERY_AAAA: + { + if (!inet_ntop(AF_INET6, data.first, formatted, sizeof(formatted))) + { + 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; + + case DNS_QUERY_CNAME: + /* 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: + 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 result; + } +} + +/** A result is ready, process it */ +DNSInfo DNSRequest::ResultIsReady(DNSHeader &header, unsigned length) +{ + unsigned i = 0, o; + int q = 0; + 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"); + + if (header.flags1 & FLAGS_MASK_OPCODE) + return std::make_pair((unsigned char*)NULL,"Unexpected value in DNS reply packet"); + + if (header.flags2 & FLAGS_MASK_RCODE) + return std::make_pair((unsigned char*)NULL,"Domain name not found"); + + if (header.ancount < 1) + return std::make_pair((unsigned char*)NULL,"No resource records returned"); + + /* Subtract the length of the header from the length of the packet */ length -= 12; - while ((unsigned)q < h.qdcount && i < length) + + while ((unsigned int)q < header.qdcount && i < length) { - if (h.payload[i] > 63) + if (header.payload[i] > 63) { i += 6; q++; } else { - if (h.payload[i] == 0) + if (header.payload[i] == 0) { q++; i += 5; } - else i += h.payload[i] + 1; + else i += header.payload[i] + 1; } } curanswer = 0; - while ((unsigned)curanswer < h.ancount) + while ((unsigned)curanswer < header.ancount) { q = 0; while (q == 0 && i < length) { - if (h.payload[i] > 63) + if (header.payload[i] > 63) { i += 2; q = 1; } else { - if (h.payload[i] == 0) + if (header.payload[i] == 0) { i++; q = 1; } - else i += h.payload[i] + 1; /* skip length and label */ + else i += header.payload[i] + 1; /* skip length and label */ } } - if (length - i < 10) - { - return NULL; - } - dns_fill_rr(&rr,&h.payload[i]); + 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++; i += rr.rdlength; continue; } - if (rr._class != this->_class) + if (rr.rr_class != this->rr_class) { curanswer++; i += rr.rdlength; @@ -512,180 +816,305 @@ unsigned char* s_connection::result_ready(s_header &h, int length) } break; } - if ((unsigned int)curanswer == h.ancount) - return NULL; + if ((unsigned int)curanswer == header.ancount) + 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 NULL; + return std::make_pair((unsigned char*)NULL,"Resource record larger than stated"); + if (rr.rdlength > 1023) - return NULL; + return std::make_pair((unsigned char*)NULL,"Resource record too large"); + + this->ttl = rr.ttl; switch (rr.type) { - case DNS_QRY_PTR: - log(DEBUG,"DNS: got a result of type DNS_QRY_PTR"); + /* + * CNAME and PTR are compressed. We need to decompress them. + */ + case DNS_QUERY_CNAME: + case DNS_QUERY_PTR: + { + unsigned short lowest_pos = length; o = 0; q = 0; while (q == 0 && i < length && o + 256 < 1023) { - if (h.payload[i] > 63) + /* DN label found (byte over 63) */ + if (header.payload[i] > 63) { - log(DEBUG,"DNS: h.payload[i] > 63"); - memcpy(&p,&h.payload[i],2); - i = ntohs(p) - 0xC000 - 12; + memcpy(&ptr,&header.payload[i],2); + + 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 { - if (h.payload[i] == 0) + if (header.payload[i] == 0) { q = 1; } else { - res[o] = '\0'; + res[o] = 0; if (o != 0) res[o++] = '.'; - memcpy(&res[o],&h.payload[i + 1],h.payload[i]); - o += h.payload[i]; - i += h.payload[i] + 1; + + 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'; + 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; - case DNS_QRY_A: - log(DEBUG,"DNS: got a result of type DNS_QRY_A"); - memcpy(res,&h.payload[i],rr.rdlength); - res[rr.rdlength] = '\0'; - break; default: - memcpy(res,&h.payload[i],rr.rdlength); - res[rr.rdlength] = '\0'; - break; + return std::make_pair((unsigned char *) NULL, "don't know how to handle undefined type (" + ConvToStr(rr.type) + ") -- rejecting"); + break; } - return res; + return std::make_pair(res,"No error"); } -DNS::DNS() +/** Close the master socket */ +DNS::~DNS() { - log(DEBUG,"Create blank DNS"); + ServerInstance->SE->Shutdown(this, 2); + ServerInstance->SE->Close(this); + ServerInstance->Timers->DelTimer(this->PruneTimer); + if (cache) + delete cache; } -DNS::~DNS() +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; } -Resolver::Resolver(const std::string &source, bool forward) : input(source), fwd(forward) +void DNS::DelCache(const std::string &source) { - if (forward) - { - this->myid = Res->dns_getip4(source.c_str()); - } - else + cache->erase(source.c_str()); +} + +void Resolver::TriggerCachedResult() +{ + 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) { - insp_inaddr binip; - if (insp_aton(source.c_str(), &binip) > 0) + time_left = CQ->CalcTTLRemaining(); + if (!time_left) + { + ServerInstance->Res->DelCache(source); + } + else if (CQ->type == qt) { - /* Valid ip address */ - this->myid = Res->dns_getname4(&binip); + cached = true; + return; } + CQ = NULL; } - if (this->myid == -1) + + switch (querytype) { - log(DEBUG,"Resolver::Resolver: Could not get an id!"); - this->OnError(RESOLVER_NSDOWN); - throw ModuleException("Resolver: Couldnt get an id to make a request"); - /* We shouldnt get here really */ - return; - } + case DNS_QUERY_A: + this->myid = ServerInstance->Res->GetIP(source.c_str()); + break; - log(DEBUG,"Resolver::Resolver: this->myid=%d",this->myid); -} + case DNS_QUERY_PTR4: + querytype = DNS_QUERY_PTR; + this->myid = ServerInstance->Res->GetNameForce(source.c_str(), PROTOCOL_IPV4); + break; -void Resolver::OnLookupComplete(const std::string &result) -{ + case DNS_QUERY_PTR6: + querytype = DNS_QUERY_PTR; + this->myid = ServerInstance->Res->GetNameForce(source.c_str(), PROTOCOL_IPV6); + break; + + case DNS_QUERY_AAAA: + this->myid = ServerInstance->Res->GetIP6(source.c_str()); + break; + + case DNS_QUERY_CNAME: + this->myid = ServerInstance->Res->GetCName(source.c_str()); + break; + + default: + ServerInstance->Logs->Log("RESOLVER",DEBUG,"DNS request with unknown query type %d", querytype); + this->myid = -1; + break; + } + if (this->myid == -1) + { + throw ModuleException("Resolver: Couldn't get an id to make a request"); + } + else + { + ServerInstance->Logs->Log("RESOLVER",DEBUG,"DNS request id %d", this->myid); + } } -void Resolver::OnError(ResolverError e) +/** Called when an error occurs */ +void Resolver::OnError(ResolverError, const std::string&) { + /* Nothing in here */ } +/** Destroy a resolver */ Resolver::~Resolver() { - log(DEBUG,"Resolver::~Resolver"); + /* Nothing here (yet) either */ } +/** Get the request id associated with this class */ int Resolver::GetId() { return this->myid; } -bool Resolver::ProcessResult(const std::string &result) +Module* Resolver::GetCreator() { - log(DEBUG,"Resolver::ProcessResult"); - - if (!result.length()) - { - log(DEBUG,"Resolver::OnError(RESOLVER_NXDOMAIN)"); - this->OnError(RESOLVER_NXDOMAIN); - return false; - } - else - { - - log(DEBUG,"Resolver::OnLookupComplete(%s)",result.c_str()); - this->OnLookupComplete(result); - return true; - } + return this->Creator; } -void dns_deal_with_classes(int fd) +/** Process a socket read event */ +void DNS::HandleEvent(EventType, int) { - log(DEBUG,"dns_deal_with_classes(%d)",fd); - if (fd == master_socket) + /* 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) { - DNSResult res = Res->dns_getresult(); - if (res.first != -1) + /* Its an error reply */ + if (res.id & ERROR_MASK) { - log(DEBUG,"Result available, id=%d",res.first); - if (dns_classes[res.first]) + /* Mask off the error bit */ + res.id -= ERROR_MASK; + /* Marshall the error to the correct class */ + if (Classes[res.id]) { - dns_classes[res.first]->ProcessResult(res.second); - delete dns_classes[res.first]; - dns_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; } + return; } + else + { + /* It is a non-error result, marshall the result to the correct class */ + if (Classes[res.id]) + { + if (ServerInstance && ServerInstance->stats) + ServerInstance->stats->statsDnsGood++; + + if (!this->GetCache(res.original.c_str())) + { + 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))); + } + + Classes[res.id]->OnLookupComplete(res.result, res.ttl, false); + delete Classes[res.id]; + Classes[res.id] = NULL; + } + } + + if (ServerInstance && ServerInstance->stats) + ServerInstance->stats->statsDns++; } } -bool dns_add_class(Resolver* r) +/** Add a derived Resolver to the working set */ +bool DNS::AddResolverClass(Resolver* r) { - log(DEBUG,"dns_add_class"); + 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)) { - if (!dns_classes[r->GetId()]) + /* Check the slot isnt already occupied - + * This should NEVER happen unless we have + * a severely broken DNS server somewhere + */ + if (!Classes[r->GetId()]) { - log(DEBUG,"dns_add_class: added class"); - dns_classes[r->GetId()] = r; + /* Set up the pointer to the class */ + Classes[r->GetId()] = r; return true; } - else - { - log(DEBUG,"Space occupied!"); - return false; - } - } - else - { - log(DEBUG,"Bad class"); - delete r; - return true; } + + /* Pointer or id not valid, or duplicate id. + * Free the item and return + */ + delete r; + return false; } -void init_dns() +void DNS::CleanResolvers(Module* module) { - Res = new DNS(); - memset(dns_classes,0,sizeof(dns_classes)); - create_socket(); + 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; + } + } + } } -