pdns/pdns_recursor.cc

   1 /*
   2     PowerDNS Versatile Database Driven Nameserver
   3     Copyright (C) 2002  PowerDNS.COM BV
   4
   5     This program is free software; you can redistribute it and/or modify
   6     it under the terms of the GNU General Public License as published by
   7     the Free Software Foundation; either version 2 of the License, or
   8     (at your option) any later version.
   9
  10     This program is distributed in the hope that it will be useful,
  11     but WITHOUT ANY WARRANTY; without even the implied warranty of
  12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13     GNU General Public License for more details.
  14
  15     You should have received a copy of the GNU General Public License
  16     along with this program; if not, write to the Free Software
  17     Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  18 */
  19
  20 #include <iostream>
  21 #include <errno.h>
  22 #include <map>
  23 #include <set>
  24 #include <netdb.h>
  25 #include <stdio.h>
  26 #include <signal.h>
  27 #include <stdlib.h>
  28 #include <unistd.h>
  29 #include "mtasker.hh"
  30 #include <utility>
  31 #include "dnspacket.hh"
  32 #include "statbag.hh"
  33 #include "arguments.hh"
  34 #include "syncres.hh"
  35
  36 extern "C" {
  37   int sem_init(sem_t*, int, unsigned int){return 0;}
  38   int sem_wait(sem_t*){return 0;}
  39   int sem_trywait(sem_t*){return 0;}
  40   int sem_post(sem_t*){return 0;}
  41   int sem_getvalue(sem_t*, int*){return 0;}
  42 }
  43
  44 StatBag S;
  45 ArgvMap &arg()
  46 {
  47   static ArgvMap theArg;
  48   return theArg;
  49 }
  50 int d_clientsock;
  51 int d_serversock;
  52
  53 struct PacketID
  54 {
  55   u_int16_t id;
  56   struct sockaddr_in remote;
  57 };
  58
  59 bool operator<(const PacketID& a, const PacketID& b)
  60 {
  61   if(a.id<b.id)
  62     return true;
  63
  64   if(a.id==b.id) {
  65     if(a.remote.sin_addr.s_addr < b.remote.sin_addr.s_addr)
  66       return true;
  67     if(a.remote.sin_addr.s_addr == b.remote.sin_addr.s_addr)
  68       if(a.remote.sin_port < b.remote.sin_port)
  69         return true;
  70   }
  71
  72   return false;
  73 }
  74
  75 MTasker<PacketID,string> MT(100000); // could probably be way lower
  76
  77 /* these two functions are used by LWRes */
  78 int asendto(const char *data, int len, int flags, struct sockaddr *toaddr, int addrlen, int id)
  79 {
  80   return sendto(d_clientsock, data, len, flags, toaddr, addrlen);
  81 }
  82
  83 int arecvfrom(char *data, int len, int flags, struct sockaddr *toaddr, socklen_t *addrlen, int *d_len, int id)
  84 {
  85   PacketID pident;
  86   pident.id=id;
  87   memcpy(&pident.remote,toaddr,sizeof(pident.remote));
  88
  89   string packet;
  90   if(!MT.waitEvent(pident,&packet,1)) { // timeout
  91     return 0;
  92   }
  93
  94   *d_len=packet.size();
  95   memcpy(data,packet.c_str(),min(len,*d_len));
  96
  97   return 1;
  98 }
  99
 100 typedef map<string,set<DNSResourceRecord> > cache_t;
 101 cache_t cache;
 102 int cacheHits, cacheMisses;
 103 int getCache(const string &qname, const QType& qt, set<DNSResourceRecord>* res)
 104 {
 105   cache_t::const_iterator j=cache.find(toLower(qname)+"|"+qt.getName());
 106   if(j!=cache.end() && j->first==toLower(qname)+"|"+qt.getName() && j->second.begin()->ttl>(unsigned int)time(0)) {
 107     if(res)
 108       *res=j->second;
 109
 110     return (unsigned int)j->second.begin()->ttl-time(0);
 111   }
 112
 113   return -1;
 114 }
 115
 116 void replaceCache(const string &qname, const QType& qt,  const set<DNSResourceRecord>& content)
 117 {
 118   cache[toLower(qname)+"|"+qt.getName()]=content;
 119 }
 120
 121 void init(void)
 122 {
 123   PacketID a, b;
 124   a.remote=b.remote;
 125   a.id=b.id;
 126
 127   // prime root cache
 128   static char*ips[]={"198.41.0.4", "128.9.0.107", "192.33.4.12", "128.8.10.90", "192.203.230.10", "192.5.5.241", "192.112.36.4", "128.63.2.53",
 129                      "192.36.148.17","192.58.128.30", "193.0.14.129", "198.32.64.12", "202.12.27.33"};
 130   DNSResourceRecord arr, nsrr;
 131   arr.qtype=QType::A;
 132   arr.ttl=time(0)+3600000;
 133   nsrr.qtype=QType::NS;
 134   nsrr.ttl=time(0)+3600000;
 135
 136   set<DNSResourceRecord>nsset;
 137   for(char c='a';c<='m';++c) {
 138     static char templ[40];
 139     strncpy(templ,"a.root-servers.net", sizeof(templ) - 1);
 140     *templ=c;
 141     arr.qname=nsrr.content=templ;
 142     arr.content=ips[c-'a'];
 143     set<DNSResourceRecord>aset;
 144     aset.insert(arr);
 145     replaceCache(string(templ),QType(QType::A),aset);
 146
 147     nsset.insert(nsrr);
 148   }
 149   replaceCache("",QType(QType::NS),nsset);
 150 }
 151
 152 void startDoResolve(void *p)
 153 {
 154   try {
 155     bool quiet=arg().mustDo("quiet");
 156     DNSPacket P=*(DNSPacket *)p;
 157
 158     delete (DNSPacket *)p;
 159
 160     vector<DNSResourceRecord>ret;
 161     DNSPacket *R=P.replyPacket();
 162     R->setA(false);
 163     R->setRA(true);
 164
 165     SyncRes sr;
 166     if(!quiet)
 167       L<<Logger::Error<<"["<<MT.getTid()<<"] question for '"<<P.qdomain<<"|"<<P.qtype.getName()<<"' from "<<P.getRemote()<<endl;
 168
 169     sr.setId(MT.getTid());
 170     if(!P.d.rd)
 171       sr.setCacheOnly();
 172
 173     int res=sr.beginResolve(P.qdomain, P.qtype, ret);
 174     if(res<0)
 175       R->setRcode(RCode::ServFail);
 176     else {
 177       R->setRcode(res);
 178       for(vector<DNSResourceRecord>::const_iterator i=ret.begin();i!=ret.end();++i)
 179         R->addRecord(*i);
 180     }
 181
 182     const char *buffer=R->getData();
 183     sendto(d_serversock,buffer,R->len,0,(struct sockaddr *)(R->remote),R->d_socklen);
 184     if(!quiet) {
 185       L<<Logger::Error<<"["<<MT.getTid()<<"] answer to "<<(P.d.rd?"":"non-rd ")<<"question '"<<P.qdomain<<"|"<<P.qtype.getName();
 186       L<<"': "<<ntohs(R->d.ancount)<<" answers, "<<ntohs(R->d.arcount)<<" additional, took "<<sr.d_outqueries<<" packets, rcode="<<res<<endl;
 187     }
 188
 189     sr.d_outqueries ? cacheMisses++ : cacheHits++;
 190
 191     delete R;
 192   }
 193   catch(AhuException &ae) {
 194     L<<Logger::Error<<"startDoResolve problem: "<<ae.reason<<endl;
 195   }
 196   catch(...) {
 197     L<<Logger::Error<<"Any other exception in a resolver context"<<endl;
 198   }
 199 }
 200
 201 void makeClientSocket()
 202 {
 203   d_clientsock=socket(AF_INET, SOCK_DGRAM,0);
 204   if(d_clientsock<0)
 205     throw AhuException("Making a socket for resolver: "+stringerror());
 206
 207   struct sockaddr_in sin;
 208   memset((char *)&sin,0, sizeof(sin));
 209
 210   sin.sin_family = AF_INET;
 211   sin.sin_addr.s_addr = INADDR_ANY;
 212
 213   int tries=10;
 214   while(--tries) {
 215     u_int16_t port=10000+random()%10000;
 216     sin.sin_port = htons(port);
 217
 218     if (bind(d_clientsock, (struct sockaddr *)&sin, sizeof(sin)) >= 0)
 219       break;
 220
 221   }
 222   if(!tries)
 223     throw AhuException("Resolver binding to local socket: "+stringerror());
 224 }
 225
 226 void makeServerSocket()
 227 {
 228   d_serversock=socket(AF_INET, SOCK_DGRAM,0);
 229   if(d_serversock<0)
 230     throw AhuException("Making a server socket for resolver: "+stringerror());
 231
 232   struct sockaddr_in sin;
 233   memset((char *)&sin,0, sizeof(sin));
 234
 235   sin.sin_family = AF_INET;
 236
 237   if(arg()["local-address"]=="0.0.0.0") {
 238     L<<Logger::Warning<<"It is advised to bind to explicit addresses with the --local-address option"<<endl;
 239     sin.sin_addr.s_addr = INADDR_ANY;
 240   }
 241   else {
 242     struct hostent *h=0;
 243     h=gethostbyname(arg()["local-address"].c_str());
 244     if(!h)
 245       throw AhuException("Unable to resolve local address");
 246
 247     sin.sin_addr.s_addr=*(int*)h->h_addr;
 248   }
 249
 250   sin.sin_port = htons(arg().asNum("local-port"));
 251
 252   if (bind(d_serversock, (struct sockaddr *)&sin, sizeof(sin))<0)
 253     throw AhuException("Resolver binding to server socket: "+stringerror());
 254   L<<Logger::Error<<"Incoming query source port: "<<arg().asNum("local-port")<<endl;
 255 }
 256 void daemonize(void)
 257 {
 258   if(fork())
 259     exit(0); // bye bye
 260
 261   setsid();
 262
 263   // cleanup open fds, but skip sockets
 264   close(0);
 265   close(1);
 266   close(2);
 267
 268 }
 269 int counter, qcounter;
 270 bool statsWanted;
 271
 272 void usr1Handler(int)
 273 {
 274   statsWanted=true;
 275 }
 276 void doStats(void)
 277 {
 278   if(qcounter) {
 279     L<<Logger::Error<<"stats: "<<qcounter<<" questions, "<<cache.size()<<" cache entries, "<<SyncRes::s_negcache.size()<<" negative entries, "
 280      <<(int)((cacheHits*100.0)/(cacheHits+cacheMisses))<<"% cache hits";
 281     L<<Logger::Error<<", outpacket/query ratio "<<(int)(SyncRes::s_outqueries*100.0/SyncRes::s_queries)<<"%"<<endl;
 282   }
 283   statsWanted=false;
 284 }
 285
 286 void houseKeeping(void *)
 287 {
 288   static time_t last_stat, last_rootupdate;
 289
 290   if(time(0)-last_stat>1800) {
 291     doStats();
 292     last_stat=time(0);
 293   }
 294   if(time(0)-last_rootupdate>7200) {
 295     SyncRes sr;
 296     vector<DNSResourceRecord>ret;
 297
 298     sr.setNoCache();
 299     int res=sr.beginResolve("", QType(QType::NS), ret);
 300     if(!res) {
 301       L<<Logger::Error<<"Refreshed . records"<<endl;
 302       last_rootupdate=time(0);
 303     }
 304     else
 305       L<<Logger::Error<<"Failed to update . records, RCODE="<<res<<endl;
 306   }
 307 }
 308
 309 int main(int argc, char **argv)
 310 {
 311   try {
 312     srandom(time(0));
 313     arg().set("soa-minimum-ttl","Don't change")="0";
 314     arg().set("soa-serial-offset","Don't change")="0";
 315     arg().set("aaaa-additional-processing","turn on to do AAAA additional processing (slow)")="off";
 316     arg().set("local-port","port to listen on")="53";
 317     arg().set("local-address","port to listen on")="0.0.0.0";
 318     arg().set("trace","if we should output heaps of logging")="off";
 319     arg().set("daemon","Operate as a daemon")="yes";
 320     arg().set("quiet","Suppress logging of questions and answers")="off";
 321     arg().set("config-dir","Location of configuration directory (recursor.conf)")=SYSCONFDIR;
 322     arg().setCmd("help","Provide a helpful message");
 323     L.toConsole(Logger::Warning);
 324     arg().laxParse(argc,argv); // do a lax parse
 325
 326     string configname=arg()["config-dir"]+"/recursor.conf";
 327     cleanSlashes(configname);
 328
 329     if(!arg().file(configname.c_str()))
 330       L<<Logger::Warning<<"Unable to parse configuration file '"<<configname<<"'"<<endl;
 331
 332     arg().parse(argc,argv);
 333
 334
 335     if(arg().mustDo("help")) {
 336       cerr<<"syntax:"<<endl<<endl;
 337       cerr<<arg().helpstring(arg()["help"])<<endl;
 338       exit(99);
 339     }
 340
 341     L.setName("pdns_recursor");
 342
 343     if(arg().mustDo("trace"))
 344       SyncRes::setLog(true);
 345
 346     makeClientSocket();
 347     makeServerSocket();
 348
 349     char data[1500];
 350     struct sockaddr_in fromaddr;
 351
 352     PacketID pident;
 353     init();
 354     L<<Logger::Warning<<"Done priming cache with root hints"<<endl;
 355
 356     if(arg().mustDo("daemon")) {
 357       L.toConsole(Logger::Critical);
 358       daemonize();
 359     }
 360     signal(SIGUSR1,usr1Handler);
 361
 362     for(;;) {
 363       while(MT.schedule()); // housekeeping, let threads do their thing
 364
 365       if(!((counter++)%100))
 366         MT.makeThread(houseKeeping,0);
 367       if(statsWanted)
 368         doStats();
 369
 370       socklen_t addrlen=sizeof(fromaddr);
 371       int d_len;
 372       DNSPacket P;
 373
 374       struct timeval tv;
 375       tv.tv_sec=0;
 376       tv.tv_usec=500000;
 377
 378       fd_set readfds;
 379       FD_ZERO( &readfds );
 380       FD_SET( d_clientsock, &readfds );
 381       FD_SET( d_serversock, &readfds );
 382       int selret = select( max(d_clientsock,d_serversock) + 1, &readfds, NULL, NULL, &tv );
 383       if(selret<=0)
 384         if (selret == -1 && errno!=EINTR)
 385           throw AhuException("Select returned: "+stringerror());
 386         else
 387           continue;
 388
 389
 390       if(FD_ISSET(d_clientsock,&readfds)) { // do we have a question response?
 391         d_len=recvfrom(d_clientsock, data, sizeof(data), 0, (sockaddr *)&fromaddr, &addrlen);
 392         if(d_len<0)
 393           continue;
 394
 395         P.setRemote((struct sockaddr *)&fromaddr, addrlen);
 396         if(P.parse(data,d_len)<0) {
 397           L<<Logger::Error<<"Unparseable packet from remote server "<<P.getRemote()<<endl;
 398         }
 399         else {
 400           if(P.d.qr) {
 401
 402             pident.remote=fromaddr;
 403             pident.id=P.d.id;
 404             string packet;
 405             packet.assign(data,d_len);
 406             MT.sendEvent(pident,&packet);
 407           }
 408           else
 409             L<<Logger::Warning<<"Ignoring question on outgoing socket from "<<P.getRemote()<<endl;
 410         }
 411       }
 412
 413       if(FD_ISSET(d_serversock,&readfds)) { // do we have a new question?
 414         d_len=recvfrom(d_serversock, data, sizeof(data), 0, (sockaddr *)&fromaddr, &addrlen);
 415         if(d_len<0)
 416           continue;
 417         P.setRemote((struct sockaddr *)&fromaddr, addrlen);
 418         if(P.parse(data,d_len)<0) {
 419           L<<Logger::Error<<"Unparseable packet from remote client "<<P.getRemote()<<endl;
 420         }
 421         else {
 422           if(P.d.qr)
 423             L<<Logger::Error<<"Ignoring answer on server socket!"<<endl;
 424           else {
 425             ++qcounter;
 426             MT.makeThread(startDoResolve,(void*)new DNSPacket(P));
 427
 428           }
 429         }
 430       }
 431     }
 432   }
 433   catch(AhuException &ae) {
 434     L<<Logger::Error<<"Exception: "<<ae.reason<<endl;
 435   }
 436   catch(exception &e) {
 437     L<<Logger::Error<<"STL Exception: "<<e.what()<<endl;
 438   }
 439   catch(...) {
 440     L<<Logger::Error<<"any other exception in main: "<<endl;
 441   }
 442 }