pdns/receiver.cc

   1 /*
   2  * This file is part of PowerDNS or dnsdist.
   3  * Copyright -- PowerDNS.COM B.V. and its contributors
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of version 2 of the GNU General Public License as
   7  * published by the Free Software Foundation.
   8  *
   9  * In addition, for the avoidance of any doubt, permission is granted to
  10  * link this program with OpenSSL and to (re)distribute the binaries
  11  * produced as the result of such linking.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  21  */
  22 #ifdef HAVE_CONFIG_H
  23 #include "config.h"
  24 #endif
  25 #include "packetcache.hh"
  26
  27 #include <cstdio>
  28 #include <signal.h>
  29 #include <cstring>
  30 #include <cstdlib>
  31 #include <sys/types.h>
  32 #include <sys/socket.h>
  33 #include <netinet/in.h>
  34 #include <arpa/inet.h>
  35 #include <iostream>
  36 #include <string>
  37 #include <sys/stat.h>
  38 #include <unistd.h>
  39 #include <sys/time.h>
  40 #include <sys/types.h>
  41 #include <sys/wait.h>
  42 #include <errno.h>
  43 #include <pthread.h>
  44 #include <unistd.h>
  45 #include <sys/mman.h>
  46 #include <fcntl.h>
  47 #include <fstream>
  48 #include <boost/algorithm/string.hpp>
  49 #ifdef HAVE_LIBSODIUM
  50 #include <sodium.h>
  51 #endif
  52 #include "opensslsigners.hh"
  53
  54 #include "dns.hh"
  55 #include "dnsbackend.hh"
  56 #include "ueberbackend.hh"
  57 #include "dnspacket.hh"
  58 #include "nameserver.hh"
  59 #include "distributor.hh"
  60 #include "logger.hh"
  61 #include "arguments.hh"
  62 #include "packethandler.hh"
  63 #include "statbag.hh"
  64 #include "tcpreceiver.hh"
  65 #include "misc.hh"
  66 #include "dynlistener.hh"
  67 #include "dynhandler.hh"
  68 #include "communicator.hh"
  69 #include "dnsproxy.hh"
  70 #include "utility.hh"
  71 #include "common_startup.hh"
  72 #include "dnsrecords.hh"
  73 #include "version.hh"
  74
  75 time_t s_starttime;
  76
  77 string s_programname="pdns"; // used in packethandler.cc
  78
  79 const char *funnytext=
  80 "*****************************************************************************\n"\
  81 "Ok, you just ran pdns_server through 'strings' hoping to find funny messages.\n"\
  82 "Well, you found one. \n"\
  83 "Two ions are flying through their particle accelerator, says the one to the\n"
  84 "other 'I think I've lost an electron!' \n"\
  85 "So the other one says, 'Are you sure?'. 'YEAH! I'M POSITIVE!'\n"\
  86 "                                            the pdns crew - pdns@powerdns.com\n"
  87 "*****************************************************************************\n";
  88
  89
  90 // start (sys)logging
  91
  92
  93 /**
  94 \file receiver.cc
  95 \brief The main loop of powerdns
  96
  97 This file is where it all happens - main is here, as are the two pivotal threads qthread() and athread()
  98 */
  99
 100 void daemonize(void)
 101 {
 102   if(fork())
 103     exit(0); // bye bye
 104
 105   setsid();
 106
 107   int i=open("/dev/null",O_RDWR); /* open stdin */
 108   if(i < 0)
 109     g_log<<Logger::Critical<<"Unable to open /dev/null: "<<stringerror()<<endl;
 110   else {
 111     dup2(i,0); /* stdin */
 112     dup2(i,1); /* stderr */
 113     dup2(i,2); /* stderr */
 114     close(i);
 115   }
 116 }
 117
 118 static int cpid;
 119 static void takedown(int i)
 120 {
 121   if(cpid) {
 122     g_log<<Logger::Error<<"Guardian is killed, taking down children with us"<<endl;
 123     kill(cpid,SIGKILL);
 124     exit(0);
 125   }
 126 }
 127
 128 static void writePid(void)
 129 {
 130   if(!::arg().mustDo("write-pid"))
 131     return;
 132
 133   string fname=::arg()["socket-dir"];
 134   if (::arg()["socket-dir"].empty()) {
 135     if (::arg()["chroot"].empty())
 136       fname = LOCALSTATEDIR;
 137     else
 138       fname = ::arg()["chroot"] + "/";
 139   } else if (!::arg()["socket-dir"].empty() && !::arg()["chroot"].empty()) {
 140     fname = ::arg()["chroot"] + ::arg()["socket-dir"];
 141   }
 142
 143   fname += + "/" + s_programname + ".pid";
 144   ofstream of(fname.c_str());
 145   if(of)
 146     of<<getpid()<<endl;
 147   else
 148     g_log<<Logger::Error<<"Writing pid for "<<getpid()<<" to "<<fname<<" failed: "<<strerror(errno)<<endl;
 149 }
 150
 151 int g_fd1[2], g_fd2[2];
 152 FILE *g_fp;
 153 pthread_mutex_t g_guardian_lock = PTHREAD_MUTEX_INITIALIZER;
 154
 155 // The next two methods are not in dynhandler.cc because they use a few items declared in this file.
 156 static string DLCycleHandler(const vector<string>&parts, pid_t ppid)
 157 {
 158   kill(cpid, SIGKILL); // why?
 159   kill(cpid, SIGKILL); // why?
 160   sleep(1);
 161   return "ok";
 162 }
 163
 164 static string DLRestHandler(const vector<string>&parts, pid_t ppid)
 165 {
 166   string line;
 167
 168   for(vector<string>::const_iterator i=parts.begin();i!=parts.end();++i) {
 169     if(i!=parts.begin())
 170       line.append(1,' ');
 171     line.append(*i);
 172   }
 173   line.append(1,'\n');
 174
 175   Lock l(&g_guardian_lock);
 176
 177   try {
 178     writen2(g_fd1[1],line.c_str(),line.size()+1);
 179   }
 180   catch(PDNSException &ae) {
 181     return "Error communicating with instance: "+ae.reason;
 182   }
 183   char mesg[512];
 184   string response;
 185   while(fgets(mesg,sizeof(mesg),g_fp)) {
 186     if(*mesg=='\0')
 187       break;
 188     response+=mesg;
 189   }
 190   boost::trim_right(response);
 191   return response;
 192 }
 193
 194
 195
 196 static int guardian(int argc, char **argv)
 197 {
 198   if(isGuarded(argv))
 199     return 0;
 200
 201   int infd=0, outfd=1;
 202
 203   DynListener dlg(s_programname);
 204   dlg.registerFunc("QUIT",&DLQuitHandler, "quit daemon");
 205   dlg.registerFunc("CYCLE",&DLCycleHandler, "restart instance");
 206   dlg.registerFunc("PING",&DLPingHandler, "ping guardian");
 207   dlg.registerFunc("STATUS",&DLStatusHandler, "get instance status from guardian");
 208   dlg.registerRestFunc(&DLRestHandler);
 209   dlg.go();
 210   string progname=argv[0];
 211
 212   bool first=true;
 213   cpid=0;
 214
 215   pthread_mutex_lock(&g_guardian_lock);
 216
 217   for(;;) {
 218     int pid;
 219     setStatus("Launching child");
 220
 221     if(pipe(g_fd1)<0 || pipe(g_fd2)<0) {
 222       g_log<<Logger::Critical<<"Unable to open pipe for coprocess: "<<strerror(errno)<<endl;
 223       exit(1);
 224     }
 225
 226     if(!(g_fp=fdopen(g_fd2[0],"r"))) {
 227       g_log<<Logger::Critical<<"Unable to associate a file pointer with pipe: "<<stringerror()<<endl;
 228       exit(1);
 229     }
 230     setbuf(g_fp,0); // no buffering please, confuses select
 231
 232     if(!(pid=fork())) { // child
 233       signal(SIGTERM, SIG_DFL);
 234
 235       signal(SIGHUP, SIG_DFL);
 236       signal(SIGUSR1, SIG_DFL);
 237       signal(SIGUSR2, SIG_DFL);
 238
 239       char **const newargv=new char*[argc+2];
 240       int n;
 241
 242       if(::arg()["config-name"]!="") {
 243         progname+="-"+::arg()["config-name"];
 244         g_log<<Logger::Error<<"Virtual configuration name: "<<::arg()["config-name"]<<endl;
 245       }
 246
 247       newargv[0]=strdup(const_cast<char *>((progname+"-instance").c_str()));
 248       for(n=1;n<argc;n++) {
 249         newargv[n]=argv[n];
 250       }
 251       newargv[n]=0;
 252
 253       g_log<<Logger::Error<<"Guardian is launching an instance"<<endl;
 254       close(g_fd1[1]);
 255       fclose(g_fp); // this closes g_fd2[0] for us
 256
 257       if(g_fd1[0]!= infd) {
 258         dup2(g_fd1[0], infd);
 259         close(g_fd1[0]);
 260       }
 261
 262       if(g_fd2[1]!= outfd) {
 263         dup2(g_fd2[1], outfd);
 264         close(g_fd2[1]);
 265       }
 266       if(execvp(argv[0], newargv)<0) {
 267         g_log<<Logger::Error<<"Unable to execvp '"<<argv[0]<<"': "<<strerror(errno)<<endl;
 268         char **p=newargv;
 269         while(*p)
 270           g_log<<Logger::Error<<*p++<<endl;
 271
 272         exit(1);
 273       }
 274       g_log<<Logger::Error<<"execvp returned!!"<<endl;
 275       // never reached
 276     }
 277     else if(pid>0) { // parent
 278       close(g_fd1[0]);
 279       close(g_fd2[1]);
 280
 281       if(first) {
 282         first=false;
 283         signal(SIGTERM, takedown);
 284
 285         signal(SIGHUP, SIG_IGN);
 286         signal(SIGUSR1, SIG_IGN);
 287         signal(SIGUSR2, SIG_IGN);
 288
 289         writePid();
 290       }
 291       pthread_mutex_unlock(&g_guardian_lock);
 292       int status;
 293       cpid=pid;
 294       for(;;) {
 295         int ret=waitpid(pid,&status,WNOHANG);
 296
 297         if(ret<0) {
 298           g_log<<Logger::Error<<"In guardian loop, waitpid returned error: "<<strerror(errno)<<endl;
 299           g_log<<Logger::Error<<"Dying"<<endl;
 300           exit(1);
 301         }
 302         else if(ret) // something exited
 303           break;
 304         else { // child is alive
 305           // execute some kind of ping here
 306           if(DLQuitPlease())
 307             takedown(1); // needs a parameter..
 308           setStatus("Child running on pid "+itoa(pid));
 309           sleep(1);
 310         }
 311       }
 312
 313       pthread_mutex_lock(&g_guardian_lock);
 314       close(g_fd1[1]);
 315       fclose(g_fp);
 316       g_fp=0;
 317
 318       if(WIFEXITED(status)) {
 319         int ret=WEXITSTATUS(status);
 320
 321         if(ret==99) {
 322           g_log<<Logger::Error<<"Child requested a stop, exiting"<<endl;
 323           exit(1);
 324         }
 325         setStatus("Child died with code "+itoa(ret));
 326         g_log<<Logger::Error<<"Our pdns instance exited with code "<<ret<<", respawning"<<endl;
 327
 328         sleep(1);
 329         continue;
 330       }
 331       if(WIFSIGNALED(status)) {
 332         int sig=WTERMSIG(status);
 333         setStatus("Child died because of signal "+itoa(sig));
 334         g_log<<Logger::Error<<"Our pdns instance ("<<pid<<") exited after signal "<<sig<<endl;
 335 #ifdef WCOREDUMP
 336         if(WCOREDUMP(status))
 337           g_log<<Logger::Error<<"Dumped core"<<endl;
 338 #endif
 339
 340         g_log<<Logger::Error<<"Respawning"<<endl;
 341         sleep(1);
 342         continue;
 343       }
 344       g_log<<Logger::Error<<"No clue what happened! Respawning"<<endl;
 345     }
 346     else {
 347       g_log<<Logger::Error<<"Unable to fork: "<<strerror(errno)<<endl;
 348       exit(1);
 349     }
 350   }
 351 }
 352
 353 static void UNIX_declareArguments()
 354 {
 355   ::arg().set("config-dir","Location of configuration directory (pdns.conf)")=SYSCONFDIR;
 356   ::arg().set("config-name","Name of this virtual configuration - will rename the binary image")="";
 357   ::arg().set("socket-dir",string("Where the controlsocket will live, ")+LOCALSTATEDIR+" when unset and not chrooted" )="";
 358   ::arg().set("module-dir","Default directory for modules")=PKGLIBDIR;
 359   ::arg().set("chroot","If set, chroot to this directory for more security")="";
 360   ::arg().set("logging-facility","Log under a specific facility")="";
 361   ::arg().set("daemon","Operate as a daemon")="no";
 362 }
 363
 364 #ifdef __GLIBC__
 365 #include <execinfo.h>
 366 static void tbhandler(int num)
 367 {
 368   g_log<<Logger::Critical<<"Got a signal "<<num<<", attempting to print trace: "<<endl;
 369   void *array[20]; //only care about last 17 functions (3 taken with tracing support)
 370   size_t size;
 371   char **strings;
 372   size_t i;
 373
 374   size = backtrace (array, 20);
 375   strings = backtrace_symbols (array, size); //Need -rdynamic gcc (linker) flag for this to work
 376
 377   for (i = 0; i < size; i++) //skip useless functions
 378     g_log<<Logger::Error<<strings[i]<<endl;
 379
 380
 381   signal(SIGABRT, SIG_DFL);
 382   abort();//hopefully will give core
 383
 384 }
 385 #endif
 386
 387 //! The main function of pdns, the pdns process
 388 int main(int argc, char **argv)
 389 {
 390   versionSetProduct(ProductAuthoritative);
 391   reportAllTypes(); // init MOADNSParser
 392
 393   s_programname="pdns";
 394   s_starttime=time(0);
 395
 396 #ifdef __GLIBC__
 397   signal(SIGSEGV,tbhandler);
 398   signal(SIGFPE,tbhandler);
 399   signal(SIGABRT,tbhandler);
 400   signal(SIGILL,tbhandler);
 401 #endif
 402
 403   std::ios_base::sync_with_stdio(false);
 404
 405   g_log.toConsole(Logger::Warning);
 406   try {
 407     declareArguments();
 408     UNIX_declareArguments();
 409
 410     ::arg().laxParse(argc,argv); // do a lax parse
 411
 412     if(::arg().mustDo("version")) {
 413       showProductVersion();
 414       showBuildConfiguration();
 415       exit(99);
 416     }
 417
 418     if(::arg()["config-name"]!="")
 419       s_programname+="-"+::arg()["config-name"];
 420
 421     g_log.setName(s_programname);
 422
 423     string configname=::arg()["config-dir"]+"/"+s_programname+".conf";
 424     cleanSlashes(configname);
 425
 426     if(!::arg().mustDo("config") && !::arg().mustDo("no-config")) // "config" == print a configuration file
 427       ::arg().laxFile(configname.c_str());
 428
 429     ::arg().laxParse(argc,argv); // reparse so the commandline still wins
 430     if(!::arg()["logging-facility"].empty()) {
 431       int val=logFacilityToLOG(::arg().asNum("logging-facility") );
 432       if(val >= 0)
 433         g_log.setFacility(val);
 434       else
 435         g_log<<Logger::Error<<"Unknown logging facility "<<::arg().asNum("logging-facility") <<endl;
 436     }
 437
 438     g_log.setLoglevel((Logger::Urgency)(::arg().asNum("loglevel")));
 439     g_log.disableSyslog(::arg().mustDo("disable-syslog"));
 440     g_log.setTimestamps(::arg().mustDo("log-timestamp"));
 441     g_log.toConsole((Logger::Urgency)(::arg().asNum("loglevel")));
 442
 443     if(::arg().mustDo("help") || ::arg().mustDo("config")) {
 444       ::arg().set("daemon")="no";
 445       ::arg().set("guardian")="no";
 446     }
 447
 448     if(::arg().mustDo("guardian") && !isGuarded(argv)) {
 449       if(::arg().mustDo("daemon")) {
 450         g_log.toConsole(Logger::Critical);
 451         daemonize();
 452       }
 453       guardian(argc, argv);
 454       // never get here, guardian will reinvoke process
 455       cerr<<"Um, we did get here!"<<endl;
 456     }
 457
 458
 459     // we really need to do work - either standalone or as an instance
 460
 461 #ifdef __GLIBC__
 462     if(!::arg().mustDo("traceback-handler")) {
 463       g_log<<Logger::Warning<<"Disabling traceback handler"<<endl;
 464       signal(SIGSEGV,SIG_DFL);
 465       signal(SIGFPE,SIG_DFL);
 466       signal(SIGABRT,SIG_DFL);
 467       signal(SIGILL,SIG_DFL);
 468     }
 469 #endif
 470
 471 #ifdef HAVE_LIBSODIUM
 472       if (sodium_init() == -1) {
 473         cerr<<"Unable to initialize sodium crypto library"<<endl;
 474         exit(99);
 475       }
 476 #endif
 477
 478     openssl_thread_setup();
 479     openssl_seed();
 480     /* setup rng */
 481     dns_random_init();
 482
 483     if(!::arg()["load-modules"].empty()) {
 484       vector<string> modules;
 485
 486       stringtok(modules,::arg()["load-modules"], ", ");
 487       if (!UeberBackend::loadModules(modules, ::arg()["module-dir"])) {
 488         exit(1);
 489       }
 490     }
 491
 492     BackendMakers().launch(::arg()["launch"]); // vrooooom!
 493
 494     if(!::arg().getCommands().empty()) {
 495       cerr<<"Fatal: non-option on the command line, perhaps a '--setting=123' statement missed the '='?"<<endl;
 496       exit(99);
 497     }
 498
 499     if(::arg().mustDo("help")) {
 500       cout<<"syntax:"<<endl<<endl;
 501       cout<<::arg().helpstring(::arg()["help"])<<endl;
 502       exit(0);
 503     }
 504
 505     if(::arg().mustDo("config")) {
 506       cout<<::arg().configstring()<<endl;
 507       exit(0);
 508     }
 509
 510     if(::arg().mustDo("list-modules")) {
 511       auto modules = BackendMakers().getModules();
 512       cout<<"Modules available:"<<endl;
 513       for(const auto& m : modules)
 514         cout<< m <<endl;
 515
 516       _exit(99);
 517     }
 518
 519     if(!::arg().asNum("local-port")) {
 520       g_log<<Logger::Error<<"Unable to launch, binding to no port or port 0 makes no sense"<<endl;
 521       exit(99); // this isn't going to fix itself either
 522     }
 523     if(!BackendMakers().numLauncheable()) {
 524       g_log<<Logger::Error<<"Unable to launch, no backends configured for querying"<<endl;
 525       exit(99); // this isn't going to fix itself either
 526     }
 527     if(::arg().mustDo("daemon")) {
 528       g_log.toConsole(Logger::None);
 529       if(!isGuarded(argv))
 530         daemonize();
 531     }
 532
 533     if(isGuarded(argv)) {
 534       g_log<<Logger::Warning<<"This is a guarded instance of pdns"<<endl;
 535       dl=new DynListener; // listens on stdin
 536     }
 537     else {
 538       g_log<<Logger::Warning<<"This is a standalone pdns"<<endl;
 539
 540       if(::arg().mustDo("control-console"))
 541         dl=new DynListener();
 542       else
 543         dl=new DynListener(s_programname);
 544
 545       writePid();
 546     }
 547     DynListener::registerFunc("SHOW",&DLShowHandler, "show a specific statistic or * to get a list", "<statistic>");
 548     DynListener::registerFunc("RPING",&DLPingHandler, "ping instance");
 549     DynListener::registerFunc("QUIT",&DLRQuitHandler, "quit daemon");
 550     DynListener::registerFunc("UPTIME",&DLUptimeHandler, "get instance uptime");
 551     DynListener::registerFunc("NOTIFY-HOST",&DLNotifyHostHandler, "notify host for specific domain", "<domain> <host>");
 552     DynListener::registerFunc("NOTIFY",&DLNotifyHandler, "queue a notification", "<domain>");
 553     DynListener::registerFunc("RELOAD",&DLReloadHandler, "reload all zones");
 554     DynListener::registerFunc("REDISCOVER",&DLRediscoverHandler, "discover any new zones");
 555     DynListener::registerFunc("VERSION",&DLVersionHandler, "get instance version");
 556     DynListener::registerFunc("PURGE",&DLPurgeHandler, "purge entries from packet cache", "[<record>]");
 557     DynListener::registerFunc("CCOUNTS",&DLCCHandler, "get cache statistics");
 558     DynListener::registerFunc("QTYPES", &DLQTypesHandler, "get QType statistics");
 559     DynListener::registerFunc("RESPSIZES", &DLRSizesHandler, "get histogram of response sizes");
 560     DynListener::registerFunc("REMOTES", &DLRemotesHandler, "get top remotes");
 561     DynListener::registerFunc("SET",&DLSettingsHandler, "set config variables", "<var> <value>");
 562     DynListener::registerFunc("RETRIEVE",&DLNotifyRetrieveHandler, "retrieve slave domain", "<domain>");
 563     DynListener::registerFunc("CURRENT-CONFIG",&DLCurrentConfigHandler, "retrieve the current configuration");
 564     DynListener::registerFunc("LIST-ZONES",&DLListZones, "show list of zones", "[master|slave|native]");
 565     DynListener::registerFunc("TOKEN-LOGIN", &DLTokenLogin, "Login to a PKCS#11 token", "<module> <slot> <pin>");
 566
 567     if(!::arg()["tcp-control-address"].empty()) {
 568       DynListener* dlTCP=new DynListener(ComboAddress(::arg()["tcp-control-address"], ::arg().asNum("tcp-control-port")));
 569       dlTCP->go();
 570     }
 571
 572     // reparse, with error checking
 573     if(!::arg().mustDo("no-config"))
 574       ::arg().file(configname.c_str());
 575     ::arg().parse(argc,argv);
 576
 577     if(::arg()["server-id"].empty()) {
 578       char tmp[128];
 579       gethostname(tmp, sizeof(tmp)-1);
 580       ::arg().set("server-id")=tmp;
 581     }
 582
 583     UeberBackend::go();
 584     N=std::make_shared<UDPNameserver>(); // this fails when we are not root, throws exception
 585     g_udpReceivers.push_back(N);
 586
 587     size_t rthreads = ::arg().asNum("receiver-threads", 1);
 588     if (rthreads > 1 && N->canReusePort()) {
 589       g_udpReceivers.resize(rthreads);
 590
 591       for (size_t idx = 1; idx < rthreads; idx++) {
 592         try {
 593           g_udpReceivers[idx] = std::make_shared<UDPNameserver>(true);
 594         }
 595         catch(const PDNSException& e) {
 596           g_log<<Logger::Error<<"Unable to reuse port, falling back to original bind"<<endl;
 597           break;
 598         }
 599       }
 600     }
 601
 602     if(!::arg().mustDo("disable-tcp"))
 603       TN=new TCPNameserver;
 604   }
 605   catch(const ArgException &A) {
 606     g_log<<Logger::Error<<"Fatal error: "<<A.reason<<endl;
 607     exit(1);
 608   }
 609
 610   declareStats();
 611   DLOG(g_log<<Logger::Warning<<"Verbose logging in effect"<<endl);
 612
 613   showProductVersion();
 614
 615   try {
 616     mainthread();
 617   }
 618   catch(PDNSException &AE) {
 619     if(!::arg().mustDo("daemon"))
 620       cerr<<"Exiting because: "<<AE.reason<<endl;
 621     g_log<<Logger::Error<<"Exiting because: "<<AE.reason<<endl;
 622   }
 623   catch(std::exception &e) {
 624     if(!::arg().mustDo("daemon"))
 625       cerr<<"Exiting because of STL error: "<<e.what()<<endl;
 626     g_log<<Logger::Error<<"Exiting because of STL error: "<<e.what()<<endl;
 627   }
 628   catch(...) {
 629     cerr<<"Uncaught exception of unknown type - sorry"<<endl;
 630   }
 631
 632   exit(1);
 633
 634 }
 635
 636