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Diffstat (limited to 'src/dns.cpp')
| -rw-r--r-- | src/dns.cpp | 1112 |
1 files changed, 0 insertions, 1112 deletions
diff --git a/src/dns.cpp b/src/dns.cpp deleted file mode 100644 index b9c605e78..000000000 --- a/src/dns.cpp +++ /dev/null @@ -1,1112 +0,0 @@ -/* - * InspIRCd -- Internet Relay Chat Daemon - * - * Copyright (C) 2012 William Pitcock <nenolod@dereferenced.org> - * Copyright (C) 2009-2010 Daniel De Graaf <danieldg@inspircd.org> - * Copyright (C) 2006, 2009 Robin Burchell <robin+git@viroteck.net> - * Copyright (C) 2007, 2009 Dennis Friis <peavey@inspircd.org> - * Copyright (C) 2008 Thomas Stagner <aquanight@inspircd.org> - * Copyright (C) 2005-2007 Craig Edwards <craigedwards@brainbox.cc> - * - * 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 <http://www.gnu.org/licenses/>. - */ - - -/* $Core */ - -/* -dns.cpp - Nonblocking DNS functions. -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. -*/ - -#ifndef _WIN32 -#include <sys/types.h> -#include <sys/socket.h> -#include <errno.h> -#include <netinet/in.h> -#include <arpa/inet.h> -#else -#include "inspircd_win32wrapper.h" -#endif - -#include "inspircd.h" -#include "socketengine.h" -#include "configreader.h" -#include "socket.h" - -#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 - */ -enum QueryInfo -{ - ERROR_MASK = 0x10000 /* Result is an error */ -}; - -/** 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 -}; - - -/** Represents a dns resource record (rr) - */ -struct ResourceRecord -{ - 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. - */ -class DNSHeader -{ - public: - unsigned char id[2]; /* Request id */ - unsigned int flags1; /* Flags */ - unsigned int flags2; /* Flags */ - unsigned int qdcount; - unsigned int ancount; /* Answer count */ - unsigned int nscount; /* Nameserver count */ - unsigned int arcount; - 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 CacheTimer : public Timer -{ - private: - DNS* dns; - public: - CacheTimer(DNS* thisdns) - : Timer(3600, ServerInstance->Time(), true), dns(thisdns) { } - - virtual bool Tick(time_t) - { - dns->PruneCache(); - return true; - } -}; - -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); - } - - bool 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; - } - return false; - } -}; - -CachedQuery::CachedQuery(const std::string &res, unsigned int ttl) : data(res) -{ - 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]); - 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]; -} - -/** 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]; - header->flags1 = input[2]; - header->flags2 = input[3]; - header->qdcount = (input[4] << 8) + input[5]; - 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],length); -} - -/** 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]; - output[2] = header->flags1; - output[3] = header->flags2; - output[4] = header->qdcount >> 8; - output[5] = header->qdcount & 0xFF; - output[6] = header->ancount >> 8; - output[7] = header->ancount & 0xFF; - output[8] = header->nscount >> 8; - output[9] = header->nscount & 0xFF; - output[10] = header->arcount >> 8; - output[11] = header->arcount & 0xFF; - memcpy(&output[12],header->payload,length); -} - -/** Send requests we have previously built down the UDP socket */ -int DNSRequest::SendRequests(const DNSHeader *header, const int length, QueryType qt) -{ - ServerInstance->Logs->Log("RESOLVER", LOG_DEBUG,"DNSRequest::SendRequests"); - - unsigned char payload[sizeof(DNSHeader)]; - - 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",LOG_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, const char* original) -{ - /* Is the DNS connection down? */ - if (this->GetFd() == -1) - return NULL; - - /* 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; - } - } - - 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; -} - -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; -} - -int DNS::PruneCache() -{ - 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++; - - delete this->cache; - this->cache = newcache; - return n; -} - -void DNS::Rehash() -{ - if (this->GetFd() > -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(); - } - - 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) - { - 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 */ - ServerInstance->Logs->Log("RESOLVER",LOG_SPARSE,"Error binding dns socket - hostnames will NOT resolve"); - ServerInstance->SE->Shutdown(this, 2); - ServerInstance->SE->Close(this); - this->SetFd(-1); - } - else if (!ServerInstance->SE->AddFd(this, FD_WANT_POLL_READ | FD_WANT_NO_WRITE)) - { - ServerInstance->Logs->Log("RESOLVER",LOG_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",LOG_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",LOG_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 */ -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) - { - length = tempchr - tempchr2; - if (payloadpos + length + 1 > 507) - return -1; - payload[payloadpos++] = length; - memcpy(&payload[payloadpos],tempchr2,length); - payloadpos += length; - tempchr2 = &tempchr[1]; - } - length = strlen(tempchr2); - if (length) - { - if (payloadpos + length + 2 > 507) - return -1; - payload[payloadpos++] = length; - memcpy(&payload[payloadpos],tempchr2,length); - payloadpos += length; - payload[payloadpos++] = 0; - } - if (payloadpos > 508) - return -1; - length = htons(rr); - memcpy(&payload[payloadpos],&length,2); - length = htons(rr_class); - memcpy(&payload[payloadpos + 2],&length,2); - return payloadpos + 4; -} - -/** 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, name); - - if ((!req) || (req->SendRequests(&h, length, DNS_QUERY_A) == -1)) - return -1; - - return id; -} - -/** Start lookup of an hostname to an IPv6 address */ -int DNS::GetIP6(const char *name) -{ - DNSHeader h; - int id; - int length; - - if ((length = this->MakePayload(name, DNS_QUERY_AAAA, 1, (unsigned char*)&h.payload)) == -1) - return -1; - - DNSRequest* req = this->AddQuery(&h, id, name); - - if ((!req) || (req->SendRequests(&h, length, DNS_QUERY_AAAA) == -1)) - return -1; - - return id; -} - -/** Start lookup of a cname to another name */ -int DNS::GetCName(const char *alias) -{ - DNSHeader h; - int id; - int length; - - if ((length = this->MakePayload(alias, DNS_QUERY_CNAME, 1, (unsigned char*)&h.payload)) == -1) - return -1; - - DNSRequest* req = this->AddQuery(&h, id, alias); - - 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) - { - in6_addr i; - if (inet_pton(AF_INET6, ip, &i) > 0) - { - DNS::MakeIP6Int(query, &i); - } - else - { - ServerInstance->Logs->Log("RESOLVER",LOG_DEBUG,"DNS::GetNameForce IPv6 bad format for '%s'", ip); - /* Invalid IP address */ - return -1; - } - } - else - { - in_addr i; - if (inet_aton(ip, &i)) - { - 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 - { - ServerInstance->Logs->Log("RESOLVER",LOG_DEBUG,"DNS::GetNameForce IPv4 bad format for '%s'", ip); - /* Invalid IP address */ - return -1; - } - } - - length = this->MakePayload(query, DNS_QUERY_PTR, 1, (unsigned char*)&h.payload); - if (length == -1) - { - ServerInstance->Logs->Log("RESOLVER",LOG_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",LOG_DEBUG,"DNS::GetNameForce can't add query (resolver down?)"); - return -1; - } - - if (req->SendRequests(&h, length, DNS_QUERY_PTR) == -1) - { - ServerInstance->Logs->Log("RESOLVER",LOG_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"; - for (int index = 31; index >= 0; index--) /* for() loop steps twice per byte */ - { - 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 */ - } - 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) - { - ServerInstance->Logs->Log("RESOLVER",LOG_DEBUG,"GetResult didn't get a full packet (len=%d)", length); - /* Nope - something screwed up. */ - 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 server, which is possible without this check. - * - * -- Thanks jilles for pointing this one out. - */ - if (from != myserver) - { - std::string server1 = from.str(); - std::string server2 = myserver.str(); - ServerInstance->Logs->Log("RESOLVER",LOG_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",LOG_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 = requests[this_id]; - requests[this_id] = NULL; - } - - /* 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: - { - inet_ntop(AF_INET6, data.first, formatted, sizeof(formatted)); - char* c = strstr(formatted,":0:"); - if (c != NULL) - { - 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); - } - 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); - break; - - default: - break; - } - - /* Build the reply with the id and hostname/ip in it */ - std::string ro = req->orig; - delete req; - return DNSResult(this_id,resultstr,ttl,ro); - } -} - -/** 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 int)q < header.qdcount && i < length) - { - if (header.payload[i] > 63) - { - i += 6; - q++; - } - else - { - if (header.payload[i] == 0) - { - q++; - i += 5; - } - else i += header.payload[i] + 1; - } - } - curanswer = 0; - while ((unsigned)curanswer < header.ancount) - { - q = 0; - while (q == 0 && i < length) - { - if (header.payload[i] > 63) - { - i += 2; - q = 1; - } - else - { - if (header.payload[i] == 0) - { - i++; - q = 1; - } - else i += header.payload[i] + 1; /* skip length and label */ - } - } - if (static_cast<int>(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",LOG_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.rr_class != this->rr_class) - { - curanswer++; - i += rr.rdlength; - continue; - } - break; - } - 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 std::make_pair((unsigned char*)NULL,"Resource record larger than stated"); - - 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: - 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); - - /* 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 (header.payload[i] == 0) - { - q = 1; - } - else - { - res[o] = 0; - if (o != 0) - res[o++] = '.'; - - 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: - 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"); -} - -/** Close the master socket */ -DNS::~DNS() -{ - 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()); -} - -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",LOG_DEBUG,"Resolver::Resolver"); - cached = false; - - CQ = ServerInstance->Res->GetCache(source); - if (CQ) - { - time_left = CQ->CalcTTLRemaining(); - if (!time_left) - { - ServerInstance->Res->DelCache(source); - } - else - { - cached = true; - return; - } - } - - switch (querytype) - { - case DNS_QUERY_A: - this->myid = ServerInstance->Res->GetIP(source.c_str()); - break; - - case DNS_QUERY_PTR4: - querytype = DNS_QUERY_PTR; - this->myid = ServerInstance->Res->GetNameForce(source.c_str(), PROTOCOL_IPV4); - break; - - 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",LOG_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",LOG_DEBUG,"DNS request id %d", this->myid); - } -} - -/** 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 */ -int Resolver::GetId() -{ - return this->myid; -} - -Module* Resolver::GetCreator() -{ - return this->Creator; -} - -/** Process a socket read event */ -void DNS::HandleEvent(EventType, int) -{ - /* Fetch the id and result of the next available packet */ - DNSResult res(0,"",0,""); - res.id = 0; - ServerInstance->Logs->Log("RESOLVER",LOG_DEBUG,"Handle DNS event"); - - res = this->GetResult(); - - ServerInstance->Logs->Log("RESOLVER",LOG_DEBUG,"Result id %d", res.id); - - /* Is there a usable request id? */ - if (res.id != -1) - { - /* Its an error reply */ - if (res.id & ERROR_MASK) - { - /* Mask off the error bit */ - res.id -= ERROR_MASK; - /* Marshall the error to the correct class */ - if (Classes[res.id]) - { - 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())) - this->cache->insert(std::make_pair(res.original.c_str(), CachedQuery(res.result, 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++; - } -} - -/** Add a derived Resolver to the working set */ -bool DNS::AddResolverClass(Resolver* r) -{ - ServerInstance->Logs->Log("RESOLVER",LOG_DEBUG,"AddResolverClass 0x%08lx", (unsigned long)r); - /* Check the pointers validity and the id's validity */ - if ((r) && (r->GetId() > -1)) - { - /* Check the slot isnt already occupied - - * This should NEVER happen unless we have - * a severely broken DNS server somewhere - */ - if (!Classes[r->GetId()]) - { - /* Set up the pointer to the class */ - Classes[r->GetId()] = r; - return true; - } - } - - /* Pointer or id not valid, or duplicate id. - * Free the item and return - */ - delete r; - return false; -} - -void DNS::CleanResolvers(Module* module) -{ - 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; - } - } - } -} |