1 /* +------------------------------------+
2 * | Inspire Internet Relay Chat Daemon |
3 * +------------------------------------+
5 * InspIRCd is copyright (C) 2002-2006 ChatSpike-Dev.
7 * <brain@chatspike.net>
8 * <Craig@chatspike.net>
10 * Written by Craig Edwards, Craig McLure, and others.
11 * This program is free but copyrighted software; see
12 * the file COPYING for details.
14 * ---------------------------------------------------
18 dns.cpp - Nonblocking DNS functions.
19 Very very loosely based on the firedns library,
20 Copyright (C) 2002 Ian Gulliver. This file is no
21 longer anything like firedns, there are many major
22 differences between this code and the original.
23 Please do not assume that firedns works like this,
24 looks like this, walks like this or tastes like this.
31 #include <sys/types.h>
32 #include <sys/socket.h>
34 #include <sys/types.h>
35 #include <sys/socket.h>
36 #include <netinet/in.h>
37 #include <arpa/inet.h>
41 #include "helperfuncs.h"
42 #include "inspircd_config.h"
43 #include "socketengine.h"
44 #include "configreader.h"
47 extern InspIRCd* ServerInstance;
48 extern ServerConfig* Config;
50 /* Master file descriptor */
51 int DNS::MasterSocket;
53 /* Masks to mask off the responses we get from the DNSRequest methods */
56 ERROR_MASK = 0x10000 /* Result is an error */
59 /* Flags which can be ORed into a request or reply for different meanings */
62 FLAGS_MASK_RD = 0x01, /* Recursive */
64 FLAGS_MASK_AA = 0x04, /* Authoritative */
65 FLAGS_MASK_OPCODE = 0x78,
67 FLAGS_MASK_RCODE = 0x0F, /* Request */
73 /* Represents a dns resource record (rr) */
77 QueryType type; /* Record type */
78 unsigned int rr_class; /* Record class */
79 unsigned long ttl; /* Time to live */
80 unsigned int rdlength; /* Record length */
83 /* Represents a dns request/reply header, and its payload as opaque data.
88 unsigned char id[2]; /* Request id */
89 unsigned int flags1; /* Flags */
90 unsigned int flags2; /* Flags */
92 unsigned int ancount; /* Answer count */
93 unsigned int nscount; /* Nameserver count */
95 unsigned char payload[512]; /* Packet payload */
98 /* Represents a request 'on the wire' with routing information relating to
99 * where to call when we get a result
104 unsigned char id[2]; /* Request id */
105 unsigned char* res; /* Result processing buffer */
106 unsigned int rr_class; /* Request class */
107 QueryType type; /* Request type */
108 insp_inaddr myserver; /* DNS server address*/
110 /* Allocate the processing buffer */
111 DNSRequest(insp_inaddr server)
113 res = new unsigned char[512];
115 memcpy(&myserver, &server, sizeof(insp_inaddr));
118 /* Deallocate the processing buffer */
124 /* Called when a result is ready to be processed which matches this id */
125 DNSInfo ResultIsReady(DNSHeader &h, int length);
127 /* Called when there are requests to be sent out */
128 int SendRequests(const DNSHeader *header, const int length, QueryType qt);
131 /* Fill a ResourceRecord class based on raw data input */
132 inline void DNS::FillResourceRecord(ResourceRecord* rr, const unsigned char *input)
134 rr->type = (QueryType)((input[0] << 8) + input[1]);
135 rr->rr_class = (input[2] << 8) + input[3];
136 rr->ttl = (input[4] << 24) + (input[5] << 16) + (input[6] << 8) + input[7];
137 rr->rdlength = (input[8] << 8) + input[9];
140 /* Fill a DNSHeader class based on raw data input of a given length */
141 inline void DNS::FillHeader(DNSHeader *header, const unsigned char *input, const int length)
143 header->id[0] = input[0];
144 header->id[1] = input[1];
145 header->flags1 = input[2];
146 header->flags2 = input[3];
147 header->qdcount = (input[4] << 8) + input[5];
148 header->ancount = (input[6] << 8) + input[7];
149 header->nscount = (input[8] << 8) + input[9];
150 header->arcount = (input[10] << 8) + input[11];
151 memcpy(header->payload,&input[12],length);
154 /* Empty a DNSHeader class out into raw data, ready for transmission */
155 inline void DNS::EmptyHeader(unsigned char *output, const DNSHeader *header, const int length)
157 output[0] = header->id[0];
158 output[1] = header->id[1];
159 output[2] = header->flags1;
160 output[3] = header->flags2;
161 output[4] = header->qdcount >> 8;
162 output[5] = header->qdcount & 0xFF;
163 output[6] = header->ancount >> 8;
164 output[7] = header->ancount & 0xFF;
165 output[8] = header->nscount >> 8;
166 output[9] = header->nscount & 0xFF;
167 output[10] = header->arcount >> 8;
168 output[11] = header->arcount & 0xFF;
169 memcpy(&output[12],header->payload,length);
172 /* Send requests we have previously built down the UDP socket */
173 int DNSRequest::SendRequests(const DNSHeader *header, const int length, QueryType qt)
176 unsigned char payload[sizeof(DNSHeader)];
181 DNS::EmptyHeader(payload,header,length);
183 memset(&addr,0,sizeof(addr));
185 memcpy(&addr.sin6_addr,&myserver,sizeof(addr.sin6_addr));
186 addr.sin6_family = AF_FAMILY;
187 addr.sin6_port = htons(DNS::QUERY_PORT);
189 memcpy(&addr.sin_addr.s_addr,&myserver,sizeof(addr.sin_addr));
190 addr.sin_family = AF_FAMILY;
191 addr.sin_port = htons(DNS::QUERY_PORT);
193 if (sendto(DNS::GetMasterSocket(), payload, length + 12, 0, (sockaddr *) &addr, sizeof(addr)) == -1)
195 log(DEBUG,"Error in sendto!");
202 /* Add a query with a predefined header, and allocate an ID for it. */
203 DNSRequest* DNS::AddQuery(DNSHeader *header, int &id)
205 /* Are there already the max number of requests on the go? */
206 if (requests.size() == DNS::MAX_REQUEST_ID + 1)
210 id = this->PRNG() & DNS::MAX_REQUEST_ID;
212 /* If this id is already 'in flight', pick another. */
213 while (requests.find(id) != requests.end())
214 id = this->PRNG() & DNS::MAX_REQUEST_ID;
216 DNSRequest* req = new DNSRequest(this->myserver);
218 header->id[0] = req->id[0] = id >> 8;
219 header->id[1] = req->id[1] = id & 0xFF;
220 header->flags1 = FLAGS_MASK_RD;
227 /* At this point we already know the id doesnt exist,
228 * so there needs to be no second check for the ::end()
232 /* According to the C++ spec, new never returns NULL. */
236 int DNS::GetMasterSocket()
241 /* Initialise the DNS UDP socket so that we can send requests */
246 /* Clear the Resolver class table */
247 memset(Classes,0,sizeof(Classes));
249 /* Set the id of the next request to 0
253 /* Clear the namesever address */
254 memset(&myserver,0,sizeof(insp_inaddr));
256 /* Convert the nameserver address into an insp_inaddr */
257 if (insp_aton(Config->DNSServer,&addr) > 0)
258 memcpy(&myserver,&addr,sizeof(insp_inaddr));
260 /* Initialize mastersocket */
261 MasterSocket = socket(PF_PROTOCOL, SOCK_DGRAM, 0);
262 if (MasterSocket != -1)
264 /* Did it succeed? */
265 if (fcntl(MasterSocket, F_SETFL, O_NONBLOCK) != 0)
267 /* Couldn't make the socket nonblocking */
268 shutdown(MasterSocket,2);
273 /* Have we got a socket and is it nonblocking? */
274 if (MasterSocket != -1)
278 memset(&addr,0,sizeof(addr));
279 addr.sin6_family = AF_FAMILY;
281 memset(&addr.sin6_addr,255,sizeof(in6_addr));
284 memset(&addr,0,sizeof(addr));
285 addr.sin_family = AF_FAMILY;
287 addr.sin_addr.s_addr = INADDR_ANY;
290 if (bind(MasterSocket,(sockaddr *)&addr,sizeof(addr)) != 0)
293 log(DEBUG,"Cant bind DNS::MasterSocket");
294 shutdown(MasterSocket,2);
299 if (MasterSocket >= 0)
301 /* Hook the descriptor into the socket engine */
302 if (ServerInstance && ServerInstance->SE)
303 ServerInstance->SE->AddFd(MasterSocket,true,X_ESTAB_DNS);
308 /* Build a payload to be placed after the header, based upon input data, a resource type, a class and a pointer to a buffer */
309 int DNS::MakePayload(const char * const name, const QueryType rr, const unsigned short rr_class, unsigned char * const payload)
311 short payloadpos = 0;
312 const char* tempchr, *tempchr2 = name;
313 unsigned short length;
315 /* split name up into labels, create query */
316 while ((tempchr = strchr(tempchr2,'.')) != NULL)
318 length = tempchr - tempchr2;
319 if (payloadpos + length + 1 > 507)
321 payload[payloadpos++] = length;
322 memcpy(&payload[payloadpos],tempchr2,length);
323 payloadpos += length;
324 tempchr2 = &tempchr[1];
326 length = strlen(tempchr2);
329 if (payloadpos + length + 2 > 507)
331 payload[payloadpos++] = length;
332 memcpy(&payload[payloadpos],tempchr2,length);
333 payloadpos += length;
334 payload[payloadpos++] = 0;
336 if (payloadpos > 508)
339 memcpy(&payload[payloadpos],&length,2);
340 length = htons(rr_class);
341 memcpy(&payload[payloadpos + 2],&length,2);
342 return payloadpos + 4;
345 /* Start lookup of an hostname to an IP address */
346 int DNS::GetIP(const char *name)
352 if ((length = this->MakePayload(name, DNS_QUERY_A, 1, (unsigned char*)&h.payload)) == -1)
355 DNSRequest* req = this->AddQuery(&h, id);
357 if ((!req) || (req->SendRequests(&h, length, DNS_QUERY_A) == -1))
363 /* Start lookup of an IP address to a hostname */
364 int DNS::GetName(const insp_inaddr *ip)
374 unsigned char* c = (unsigned char*)&ip->s_addr;
376 sprintf(query,"%d.%d.%d.%d.in-addr.arpa",c[3],c[2],c[1],c[0]);
378 if ((length = this->MakePayload(query, DNS_QUERY_PTR, 1, (unsigned char*)&h.payload)) == -1)
381 DNSRequest* req = this->AddQuery(&h, id);
383 if ((!req) || (req->SendRequests(&h, length, DNS_QUERY_PTR) == -1))
390 /* Return the next id which is ready, and the result attached to it */
391 DNSResult DNS::GetResult()
393 /* Fetch dns query response and decide where it belongs */
396 unsigned char buffer[sizeof(DNSHeader)];
398 socklen_t x = sizeof(from);
399 const char* ipaddr_from = "";
400 unsigned short int port_from = 0;
402 int length = recvfrom(MasterSocket,buffer,sizeof(DNSHeader),0,&from,&x);
404 /* Did we get the whole header? */
406 /* Nope - something screwed up. */
407 return std::make_pair(-1,"");
409 /* Check wether the reply came from a different DNS
410 * server to the one we sent it to, or the source-port
412 * A user could in theory still spoof dns packets anyway
413 * but this is less trivial than just sending garbage
414 * to the client, which is possible without this check.
416 * -- Thanks jilles for pointing this one out.
419 ipaddr_from = insp_ntoa(((sockaddr_in*)&from)->sin6_addr);
420 port_from = ntohs(((sockaddr_in*)&from)->sin6_port);
422 ipaddr_from = insp_ntoa(((sockaddr_in*)&from)->sin_addr);
423 port_from = ntohs(((sockaddr_in*)&from)->sin_port);
426 if ((port_from != DNS::QUERY_PORT) || (strcasecmp(ipaddr_from, Config->DNSServer)))
427 return std::make_pair(-1,"");
429 /* Put the read header info into a header class */
430 DNS::FillHeader(&header,buffer,length - 12);
432 /* Get the id of this request.
433 * Its a 16 bit value stored in two char's,
434 * so we use logic shifts to create the value.
436 unsigned long this_id = header.id[1] + (header.id[0] << 8);
438 /* Do we have a pending request matching this id? */
439 requestlist_iter n_iter = requests.find(this_id);
440 if (n_iter == requests.end())
442 /* Somehow we got a DNS response for a request we never made... */
443 log(DEBUG,"DNS: got a response for a query we didnt send with fd=%d queryid=%d",MasterSocket,this_id);
444 return std::make_pair(-1,"");
448 /* Remove the query from the list of pending queries */
449 req = (DNSRequest*)n_iter->second;
450 requests.erase(n_iter);
453 /* Inform the DNSRequest class that it has a result to be read.
454 * When its finished it will return a DNSInfo which is a pair of
455 * unsigned char* resource record data, and an error message.
457 DNSInfo data = req->ResultIsReady(header, length);
458 std::string resultstr;
460 /* Check if we got a result, if we didnt, its an error */
461 if (data.first == NULL)
464 * Mask the ID with the value of ERROR_MASK, so that
465 * the dns_deal_with_classes() function knows that its
466 * an error response and needs to be treated uniquely.
467 * Put the error message in the second field.
470 return std::make_pair(this_id | ERROR_MASK, data.second);
474 /* Forward lookups come back as binary data. We must format them into ascii */
475 if (req->type == DNS_QUERY_A)
478 snprintf(formatted,16,"%u.%u.%u.%u",data.first[0],data.first[1],data.first[2],data.first[3]);
479 resultstr = formatted;
483 /* Reverse lookups just come back as char* */
484 resultstr = std::string((const char*)data.first);
487 /* Build the reply with the id and hostname/ip in it */
489 return std::make_pair(this_id,resultstr);
493 /* A result is ready, process it */
494 DNSInfo DNSRequest::ResultIsReady(DNSHeader &header, int length)
502 if (!(header.flags1 & FLAGS_MASK_QR))
503 return std::make_pair((unsigned char*)NULL,"Not a query result");
505 if (header.flags1 & FLAGS_MASK_OPCODE)
506 return std::make_pair((unsigned char*)NULL,"Unexpected value in DNS reply packet");
508 if (header.flags2 & FLAGS_MASK_RCODE)
509 return std::make_pair((unsigned char*)NULL,"Domain name not found");
511 if (header.ancount < 1)
512 return std::make_pair((unsigned char*)NULL,"No resource records returned");
514 /* Subtract the length of the header from the length of the packet */
517 while ((unsigned int)q < header.qdcount && i < length)
519 if (header.payload[i] > 63)
526 if (header.payload[i] == 0)
531 else i += header.payload[i] + 1;
535 while ((unsigned)curanswer < header.ancount)
538 while (q == 0 && i < length)
540 if (header.payload[i] > 63)
547 if (header.payload[i] == 0)
552 else i += header.payload[i] + 1; /* skip length and label */
556 return std::make_pair((unsigned char*)NULL,"Incorrectly sized DNS reply");
558 DNS::FillResourceRecord(&rr,&header.payload[i]);
560 if (rr.type != this->type)
566 if (rr.rr_class != this->rr_class)
574 if ((unsigned int)curanswer == header.ancount)
575 return std::make_pair((unsigned char*)NULL,"No valid answers");
577 if (i + rr.rdlength > (unsigned int)length)
578 return std::make_pair((unsigned char*)NULL,"Resource record larger than stated");
580 if (rr.rdlength > 1023)
581 return std::make_pair((unsigned char*)NULL,"Resource record too large");
588 while (q == 0 && i < length && o + 256 < 1023)
590 if (header.payload[i] > 63)
592 memcpy(&ptr,&header.payload[i],2);
593 i = ntohs(ptr) - 0xC000 - 12;
597 if (header.payload[i] == 0)
606 memcpy(&res[o],&header.payload[i + 1],header.payload[i]);
607 o += header.payload[i];
608 i += header.payload[i] + 1;
615 memcpy(res,&header.payload[i],rr.rdlength);
616 res[rr.rdlength] = 0;
619 memcpy(res,&header.payload[i],rr.rdlength);
620 res[rr.rdlength] = 0;
623 return std::make_pair(res,"No error");;
626 /* Close the master socket */
629 shutdown(MasterSocket, 2);
633 /* High level abstraction of dns used by application at large */
634 Resolver::Resolver(const std::string &source, bool forward) : input(source), fwd(forward)
638 log(DEBUG,"Resolver: Forward lookup on %s",source.c_str());
639 this->myid = ServerInstance->Res->GetIP(source.c_str());
643 log(DEBUG,"Resolver: Reverse lookup on %s",source.c_str());
645 if (insp_aton(source.c_str(), &binip) > 0)
647 /* Valid ip address */
648 this->myid = ServerInstance->Res->GetName(&binip);
652 this->OnError(RESOLVER_BADIP, "Bad IP address for reverse lookup");
653 throw ModuleException("Resolver: Bad IP address");
657 if (this->myid == -1)
659 log(DEBUG,"Resolver::Resolver: Could not get an id!");
660 this->OnError(RESOLVER_NSDOWN, "Nameserver is down");
661 throw ModuleException("Resolver: Couldnt get an id to make a request");
662 /* We shouldnt get here really */
666 log(DEBUG,"Resolver::Resolver: this->myid=%d",this->myid);
669 void Resolver::OnError(ResolverError e, const std::string &errormessage)
671 /* Nothing in here */
674 Resolver::~Resolver()
676 /* Nothing here (yet) either */
679 /* Get the request id associated with this class */
680 int Resolver::GetId()
685 /* Process a socket read event */
686 void DNS::MarshallReads(int fd)
688 /* We are only intrested in our single fd */
689 if (fd == GetMasterSocket())
691 /* Fetch the id and result of the next available packet */
692 DNSResult res = this->GetResult();
693 /* Is there a usable request id? */
696 /* Its an error reply */
697 if (res.first & ERROR_MASK)
699 /* Mask off the error bit */
700 res.first -= ERROR_MASK;
702 /* Marshall the error to the correct class */
703 log(DEBUG,"Error available, id=%d",res.first);
704 if (Classes[res.first])
706 if (ServerInstance && ServerInstance->stats)
707 ServerInstance->stats->statsDnsBad++;
708 Classes[res.first]->OnError(RESOLVER_NXDOMAIN, res.second);
709 delete Classes[res.first];
710 Classes[res.first] = NULL;
715 /* It is a non-error result */
716 log(DEBUG,"Result available, id=%d",res.first);
717 /* Marshall the result to the correct class */
718 if (Classes[res.first])
720 if (ServerInstance && ServerInstance->stats)
721 ServerInstance->stats->statsDnsGood++;
722 Classes[res.first]->OnLookupComplete(res.second);
723 delete Classes[res.first];
724 Classes[res.first] = NULL;
728 if (ServerInstance && ServerInstance->stats)
729 ServerInstance->stats->statsDns++;
735 /* Add a derived Resolver to the working set */
736 bool DNS::AddResolverClass(Resolver* r)
738 /* Check the pointers validity and the id's validity */
739 if ((r) && (r->GetId() > -1))
741 /* Check the slot isnt already occupied -
742 * This should NEVER happen unless we have
743 * a severely broken DNS server somewhere
745 if (!Classes[r->GetId()])
747 /* Set up the pointer to the class */
748 Classes[r->GetId()] = r;
757 /* Pointer or id not valid.
758 * Free the item and return
767 unsigned long DNS::PRNG()
769 unsigned long val = 0;
771 serverstats* s = ServerInstance->stats;
772 gettimeofday(&n,NULL);
773 val = (n.tv_usec ^ getpid() ^ geteuid() ^ (this->currid++)) ^ s->statsAccept + n.tv_sec;
774 val = val + s->statsCollisions ^ s->statsDnsGood - s->statsDnsBad;
775 val += (s->statsConnects ^ (unsigned long)s->statsSent ^ (unsigned long)s->statsRecv) - s->BoundPortCount;