pdns/receiver.cc

   1 /*
   2     PowerDNS Versatile Database Driven Nameserver
   3     Copyright (C) 2002 - 2013  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 version 2
   7     as published by the Free Software Foundation
   8
   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., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  18 */
  19 #include "packetcache.hh"
  20
  21 #include <cstdio>
  22 #include <signal.h>
  23 #include <cstring>
  24 #include <cstdlib>
  25 #include <sys/types.h>
  26 #include <sys/socket.h>
  27 #include <netinet/in.h>
  28 #include <arpa/inet.h>
  29 #include <iostream>
  30 #include <string>
  31 #include <sys/stat.h>
  32 #include <unistd.h>
  33 #include <sys/time.h>
  34 #include <sys/types.h>
  35 #include <sys/wait.h>
  36 #include <errno.h>
  37 #include <pthread.h>
  38 #include <unistd.h>
  39 #include <sys/mman.h>
  40 #include <fcntl.h>
  41 #include <fstream>
  42 #include <boost/algorithm/string.hpp>
  43
  44 #include "config.h"
  45 #include "dns.hh"
  46 #include "dnsbackend.hh"
  47 #include "ueberbackend.hh"
  48 #include "dnspacket.hh"
  49 #include "nameserver.hh"
  50 #include "distributor.hh"
  51 #include "logger.hh"
  52 #include "arguments.hh"
  53 #include "packethandler.hh"
  54 #include "statbag.hh"
  55 #include "tcpreceiver.hh"
  56 #include "ws.hh"
  57 #include "misc.hh"
  58 #include "dynlistener.hh"
  59 #include "dynhandler.hh"
  60 #include "communicator.hh"
  61 #include "dnsproxy.hh"
  62 #include "utility.hh"
  63 #include "common_startup.hh"
  64 #include "dnsrecords.hh"
  65 #include "version.hh"
  66
  67
  68 time_t s_starttime;
  69
  70 string s_programname="pdns"; // used in packethandler.cc
  71
  72 const char *funnytext=
  73 "*****************************************************************************\n"\
  74 "Ok, you just ran pdns_server through 'strings' hoping to find funny messages.\n"\
  75 "Well, you found one. \n"\
  76 "Two ions are flying through their particle accelerator, says the one to the\n"
  77 "other 'I think I've lost an electron!' \n"\
  78 "So the other one says, 'Are you sure?'. 'YEAH! I'M POSITIVE!'\n"\
  79 "                                            the pdns crew - pdns@powerdns.com\n"
  80 "*****************************************************************************\n";
  81
  82
  83 // start (sys)logging
  84
  85 /** \var Logger L
  86 \brief All logging is done via L, a Logger instance
  87 */
  88
  89
  90 /**
  91 \file receiver.cc
  92 \brief The main loop of powerdns
  93
  94 This file is where it all happens - main is here, as are the two pivotal threads qthread() and athread()
  95 */
  96
  97 void daemonize(void)
  98 {
  99   if(fork())
 100     exit(0); // bye bye
 101
 102   setsid();
 103
 104   int i=open("/dev/null",O_RDWR); /* open stdin */
 105   if(i < 0)
 106     L<<Logger::Critical<<"Unable to open /dev/null: "<<stringerror()<<endl;
 107   else {
 108     dup2(i,0); /* stdin */
 109     dup2(i,1); /* stderr */
 110     dup2(i,2); /* stderr */
 111     close(i);
 112   }
 113 }
 114
 115 static int cpid;
 116 static void takedown(int i)
 117 {
 118   if(cpid) {
 119     L<<Logger::Error<<"Guardian is killed, taking down children with us"<<endl;
 120     kill(cpid,SIGKILL);
 121     exit(0);
 122   }
 123 }
 124
 125 static void writePid(void)
 126 {
 127   string fname=::arg()["socket-dir"]+"/"+s_programname+".pid";
 128   ofstream of(fname.c_str());
 129   if(of)
 130     of<<getpid()<<endl;
 131   else
 132     L<<Logger::Error<<"Requested to write pid for "<<getpid()<<" to "<<fname<<" failed: "<<strerror(errno)<<endl;
 133 }
 134
 135 int g_fd1[2], g_fd2[2];
 136 FILE *g_fp;
 137 pthread_mutex_t g_guardian_lock = PTHREAD_MUTEX_INITIALIZER;
 138
 139 // The next two methods are not in dynhandler.cc because they use a few items declared in this file.
 140 static string DLCycleHandler(const vector<string>&parts, pid_t ppid)
 141 {
 142   kill(cpid, SIGKILL); // why?
 143   kill(cpid, SIGKILL); // why?
 144   sleep(1);
 145   return "ok";
 146 }
 147
 148 static string DLRestHandler(const vector<string>&parts, pid_t ppid)
 149 {
 150   string line;
 151
 152   for(vector<string>::const_iterator i=parts.begin();i!=parts.end();++i) {
 153     if(i!=parts.begin())
 154       line.append(1,' ');
 155     line.append(*i);
 156   }
 157   line.append(1,'\n');
 158
 159   Lock l(&g_guardian_lock);
 160
 161   try {
 162     writen2(g_fd1[1],line.c_str(),line.size()+1);
 163   }
 164   catch(PDNSException &ae) {
 165     return "Error communicating with instance: "+ae.reason;
 166   }
 167   char mesg[512];
 168   string response;
 169   while(fgets(mesg,sizeof(mesg),g_fp)) {
 170     if(*mesg=='\0')
 171       break;
 172     response+=mesg;
 173   }
 174   boost::trim_right(response);
 175   return response;
 176 }
 177
 178
 179
 180 static int guardian(int argc, char **argv)
 181 {
 182   if(isGuarded(argv))
 183     return 0;
 184
 185   int infd=0, outfd=1;
 186
 187   DynListener dlg(s_programname);
 188   dlg.registerFunc("QUIT",&DLQuitHandler, "quit daemon");
 189   dlg.registerFunc("CYCLE",&DLCycleHandler, "restart instance");
 190   dlg.registerFunc("PING",&DLPingHandler, "ping guardian");
 191   dlg.registerFunc("STATUS",&DLStatusHandler, "get instance status from guardian");
 192   dlg.registerRestFunc(&DLRestHandler);
 193   dlg.go();
 194   string progname=argv[0];
 195
 196   bool first=true;
 197   cpid=0;
 198
 199   pthread_mutex_lock(&g_guardian_lock);
 200
 201   for(;;) {
 202     int pid;
 203     setStatus("Launching child");
 204
 205     if(pipe(g_fd1)<0 || pipe(g_fd2)<0) {
 206       L<<Logger::Critical<<"Unable to open pipe for coprocess: "<<strerror(errno)<<endl;
 207       exit(1);
 208     }
 209
 210     if(!(g_fp=fdopen(g_fd2[0],"r"))) {
 211       L<<Logger::Critical<<"Unable to associate a file pointer with pipe: "<<stringerror()<<endl;
 212       exit(1);
 213     }
 214     setbuf(g_fp,0); // no buffering please, confuses select
 215
 216     if(!(pid=fork())) { // child
 217       signal(SIGTERM, SIG_DFL);
 218
 219       signal(SIGHUP, SIG_DFL);
 220       signal(SIGUSR1, SIG_DFL);
 221       signal(SIGUSR2, SIG_DFL);
 222
 223       char **const newargv=new char*[argc+2];
 224       int n;
 225
 226       if(::arg()["config-name"]!="") {
 227         progname+="-"+::arg()["config-name"];
 228         L<<Logger::Error<<"Virtual configuration name: "<<::arg()["config-name"]<<endl;
 229       }
 230
 231       newargv[0]=strdup(const_cast<char *>((progname+"-instance").c_str()));
 232       for(n=1;n<argc;n++) {
 233         newargv[n]=argv[n];
 234       }
 235       newargv[n]=0;
 236
 237       L<<Logger::Error<<"Guardian is launching an instance"<<endl;
 238       close(g_fd1[1]);
 239       fclose(g_fp); // this closes g_fd2[0] for us
 240
 241       if(g_fd1[0]!= infd) {
 242         dup2(g_fd1[0], infd);
 243         close(g_fd1[0]);
 244       }
 245
 246       if(g_fd2[1]!= outfd) {
 247         dup2(g_fd2[1], outfd);
 248         close(g_fd2[1]);
 249       }
 250       if(execvp(argv[0], newargv)<0) {
 251         L<<Logger::Error<<"Unable to execvp '"<<argv[0]<<"': "<<strerror(errno)<<endl;
 252         char **p=newargv;
 253         while(*p)
 254           L<<Logger::Error<<*p++<<endl;
 255
 256         exit(1);
 257       }
 258       L<<Logger::Error<<"execvp returned!!"<<endl;
 259       // never reached
 260     }
 261     else if(pid>0) { // parent
 262       close(g_fd1[0]);
 263       close(g_fd2[1]);
 264
 265       if(first) {
 266         first=false;
 267         signal(SIGTERM, takedown);
 268
 269         signal(SIGHUP, SIG_IGN);
 270         signal(SIGUSR1, SIG_IGN);
 271         signal(SIGUSR2, SIG_IGN);
 272
 273         writePid();
 274       }
 275       pthread_mutex_unlock(&g_guardian_lock);
 276       int status;
 277       cpid=pid;
 278       for(;;) {
 279         int ret=waitpid(pid,&status,WNOHANG);
 280
 281         if(ret<0) {
 282           L<<Logger::Error<<"In guardian loop, waitpid returned error: "<<strerror(errno)<<endl;
 283           L<<Logger::Error<<"Dying"<<endl;
 284           exit(1);
 285         }
 286         else if(ret) // something exited
 287           break;
 288         else { // child is alive
 289           // execute some kind of ping here
 290           if(DLQuitPlease())
 291             takedown(1); // needs a parameter..
 292           setStatus("Child running on pid "+itoa(pid));
 293           sleep(1);
 294         }
 295       }
 296
 297       pthread_mutex_lock(&g_guardian_lock);
 298       close(g_fd1[1]);
 299       fclose(g_fp);
 300       g_fp=0;
 301
 302       if(WIFEXITED(status)) {
 303         int ret=WEXITSTATUS(status);
 304
 305         if(ret==99) {
 306           L<<Logger::Error<<"Child requested a stop, exiting"<<endl;
 307           exit(1);
 308         }
 309         setStatus("Child died with code "+itoa(ret));
 310         L<<Logger::Error<<"Our pdns instance exited with code "<<ret<<endl;
 311         L<<Logger::Error<<"Respawning"<<endl;
 312
 313         sleep(1);
 314         continue;
 315       }
 316       if(WIFSIGNALED(status)) {
 317         int sig=WTERMSIG(status);
 318         setStatus("Child died because of signal "+itoa(sig));
 319         L<<Logger::Error<<"Our pdns instance ("<<pid<<") exited after signal "<<sig<<endl;
 320 #ifdef WCOREDUMP
 321         if(WCOREDUMP(status))
 322           L<<Logger::Error<<"Dumped core"<<endl;
 323 #endif
 324
 325         L<<Logger::Error<<"Respawning"<<endl;
 326         sleep(1);
 327         continue;
 328       }
 329       L<<Logger::Error<<"No clue what happened! Respawning"<<endl;
 330     }
 331     else {
 332       L<<Logger::Error<<"Unable to fork: "<<strerror(errno)<<endl;
 333       exit(1);
 334     }
 335   }
 336 }
 337
 338 static void UNIX_declareArguments()
 339 {
 340   ::arg().set("config-dir","Location of configuration directory (pdns.conf)")=SYSCONFDIR;
 341   ::arg().set("config-name","Name of this virtual configuration - will rename the binary image")="";
 342   ::arg().set("socket-dir","Where the controlsocket will live")=LOCALSTATEDIR;
 343   ::arg().set("module-dir","Default directory for modules")=LIBDIR;
 344   ::arg().set("chroot","If set, chroot to this directory for more security")="";
 345   ::arg().set("logging-facility","Log under a specific facility")="";
 346   ::arg().set("daemon","Operate as a daemon")="no";
 347
 348 }
 349
 350 static void loadModules()
 351 {
 352   if(!::arg()["load-modules"].empty()) {
 353     vector<string>modules;
 354
 355     stringtok(modules,::arg()["load-modules"],",");
 356
 357     for(vector<string>::const_iterator i=modules.begin();i!=modules.end();++i) {
 358       bool res;
 359       const string &module=*i;
 360
 361       if(module.find(".")==string::npos)
 362         res=UeberBackend::loadmodule(::arg()["module-dir"]+"/lib"+module+"backend.so");
 363       else if(module[0]=='/' || (module[0]=='.' && module[1]=='/') || (module[0]=='.' && module[1]=='.'))    // absolute or current path
 364         res=UeberBackend::loadmodule(module);
 365       else
 366         res=UeberBackend::loadmodule(::arg()["module-dir"]+"/"+module);
 367
 368       if(res==false) {
 369         L<<Logger::Error<<"receiver unable to load module "<<module<<endl;
 370         exit(1);
 371       }
 372     }
 373   }
 374 }
 375
 376 #ifdef __linux__
 377 #include <execinfo.h>
 378 static void tbhandler(int num)
 379 {
 380   L<<Logger::Critical<<"Got a signal "<<num<<", attempting to print trace: "<<endl;
 381   void *array[20]; //only care about last 17 functions (3 taken with tracing support)
 382   size_t size;
 383   char **strings;
 384   size_t i;
 385
 386   size = backtrace (array, 20);
 387   strings = backtrace_symbols (array, size); //Need -rdynamic gcc (linker) flag for this to work
 388
 389   for (i = 0; i < size; i++) //skip useless functions
 390     L<<Logger::Error<<strings[i]<<endl;
 391
 392
 393   signal(SIGABRT, SIG_DFL);
 394   abort();//hopefully will give core
 395
 396 }
 397 #endif
 398
 399 //! The main function of pdns, the pdns process
 400 int main(int argc, char **argv)
 401 {
 402   versionSetProduct("Authoritative Server");
 403   reportAllTypes(); // init MOADNSParser
 404
 405   s_programname="pdns";
 406   s_starttime=time(0);
 407
 408 #ifdef __linux__
 409   signal(SIGSEGV,tbhandler);
 410   signal(SIGFPE,tbhandler);
 411   signal(SIGABRT,tbhandler);
 412   signal(SIGILL,tbhandler);
 413 #endif
 414
 415 #if __GNUC__ >= 3
 416   std::ios_base::sync_with_stdio(false);
 417 #endif
 418
 419   L.toConsole(Logger::Warning);
 420   try {
 421     declareArguments();
 422     UNIX_declareArguments();
 423
 424     ::arg().laxParse(argc,argv); // do a lax parse
 425
 426     if(::arg().mustDo("version")) {
 427       showProductVersion();
 428       exit(99);
 429     }
 430
 431     if(::arg()["config-name"]!="")
 432       s_programname+="-"+::arg()["config-name"];
 433
 434     (void)theL(s_programname);
 435
 436     string configname=::arg()["config-dir"]+"/"+s_programname+".conf";
 437     cleanSlashes(configname);
 438
 439     if(!::arg().mustDo("config") && !::arg().mustDo("no-config")) // "config" == print a configuration file
 440       ::arg().laxFile(configname.c_str());
 441
 442     ::arg().laxParse(argc,argv); // reparse so the commandline still wins
 443     if(!::arg()["logging-facility"].empty()) {
 444       int val=logFacilityToLOG(::arg().asNum("logging-facility") );
 445       if(val >= 0)
 446         theL().setFacility(val);
 447       else
 448         L<<Logger::Error<<"Unknown logging facility "<<::arg().asNum("logging-facility") <<endl;
 449     }
 450
 451     L.setLoglevel((Logger::Urgency)(::arg().asNum("loglevel")));
 452     L.toConsole((Logger::Urgency)(::arg().asNum("loglevel")));
 453
 454     if(::arg().mustDo("help") || ::arg().mustDo("config")) {
 455       ::arg().set("daemon")="no";
 456       ::arg().set("guardian")="no";
 457     }
 458
 459     if(::arg().mustDo("guardian") && !isGuarded(argv)) {
 460       if(::arg().mustDo("daemon")) {
 461         L.toConsole(Logger::Critical);
 462         daemonize();
 463       }
 464       guardian(argc, argv);
 465       // never get here, guardian will reinvoke process
 466       cerr<<"Um, we did get here!"<<endl;
 467     }
 468
 469
 470     // we really need to do work - either standalone or as an instance
 471
 472 #ifdef __linux__
 473     if(!::arg().mustDo("traceback-handler")) {
 474       L<<Logger::Warning<<"Disabling traceback handler"<<endl;
 475       signal(SIGSEGV,SIG_DFL);
 476       signal(SIGFPE,SIG_DFL);
 477       signal(SIGABRT,SIG_DFL);
 478       signal(SIGILL,SIG_DFL);
 479     }
 480 #endif
 481
 482     seedRandom(::arg()["entropy-source"]);
 483
 484     loadModules();
 485     BackendMakers().launch(::arg()["launch"]); // vrooooom!
 486
 487     if(!::arg().getCommands().empty()) {
 488       cerr<<"Fatal: non-option on the command line, perhaps a '--setting=123' statement missed the '='?"<<endl;
 489       exit(99);
 490     }
 491
 492     if(::arg().mustDo("help")) {
 493       cerr<<"syntax:"<<endl<<endl;
 494       cerr<<::arg().helpstring(::arg()["help"])<<endl;
 495       exit(99);
 496     }
 497
 498     if(::arg().mustDo("config")) {
 499       cout<<::arg().configstring()<<endl;
 500       exit(99);
 501     }
 502
 503     if(::arg().mustDo("list-modules")) {
 504       vector<string>modules=BackendMakers().getModules();
 505       cerr<<"Modules available:"<<endl;
 506       for(vector<string>::const_iterator i=modules.begin();i!=modules.end();++i)
 507         cout<<*i<<endl;
 508
 509       exit(99);
 510     }
 511
 512     if(::arg().mustDo("fancy-records")) {
 513       reportFancyTypes();
 514     }
 515
 516     if(!::arg().asNum("local-port")) {
 517       L<<Logger::Error<<"Unable to launch, binding to no port or port 0 makes no sense"<<endl;
 518       exit(99); // this isn't going to fix itself either
 519     }
 520     if(!BackendMakers().numLauncheable()) {
 521       L<<Logger::Error<<"Unable to launch, no backends configured for querying"<<endl;
 522       exit(99); // this isn't going to fix itself either
 523     }
 524     if(::arg().mustDo("daemon")) {
 525       L.toConsole(Logger::None);
 526       if(!isGuarded(argv))
 527         daemonize();
 528     }
 529
 530     if(isGuarded(argv)) {
 531       L<<Logger::Warning<<"This is a guarded instance of pdns"<<endl;
 532       dl=new DynListener; // listens on stdin
 533     }
 534     else {
 535       L<<Logger::Warning<<"This is a standalone pdns"<<endl;
 536
 537       if(::arg().mustDo("control-console"))
 538         dl=new DynListener();
 539       else
 540         dl=new DynListener(s_programname);
 541
 542       writePid();
 543     }
 544     DynListener::registerFunc("SHOW",&DLShowHandler, "show a specific statistic or * to get a list", "<statistic>");
 545     DynListener::registerFunc("RPING",&DLPingHandler, "ping instance");
 546     DynListener::registerFunc("QUIT",&DLRQuitHandler, "quit daemon");
 547     DynListener::registerFunc("UPTIME",&DLUptimeHandler, "get instance uptime");
 548     DynListener::registerFunc("NOTIFY-HOST",&DLNotifyHostHandler, "notify host for specific domain", "<domain> <host>");
 549     DynListener::registerFunc("NOTIFY",&DLNotifyHandler, "queue a notification", "<domain>");
 550     DynListener::registerFunc("RELOAD",&DLReloadHandler, "reload all zones");
 551     DynListener::registerFunc("REDISCOVER",&DLRediscoverHandler, "discover any new zones");
 552     DynListener::registerFunc("VERSION",&DLVersionHandler, "get instance version");
 553     DynListener::registerFunc("PURGE",&DLPurgeHandler, "purge entries from packet cache", "[<record>]");
 554     DynListener::registerFunc("CCOUNTS",&DLCCHandler, "get cache statistics");
 555     DynListener::registerFunc("QTYPES", &DLQTypesHandler, "get QType statistics");
 556     DynListener::registerFunc("RESPSIZES", &DLRSizesHandler, "get histogram of response sizes");
 557     DynListener::registerFunc("REMOTES", &DLRemotesHandler, "get top remotes");
 558     DynListener::registerFunc("SET",&DLSettingsHandler, "set config variables", "<var> <value>");
 559     DynListener::registerFunc("RETRIEVE",&DLNotifyRetrieveHandler, "retrieve slave domain", "<domain>");
 560     DynListener::registerFunc("CURRENT-CONFIG",&DLCurrentConfigHandler, "Retrieve the current configuration");
 561
 562     if(!::arg()["tcp-control-address"].empty()) {
 563       DynListener* dlTCP=new DynListener(ComboAddress(::arg()["tcp-control-address"], ::arg().asNum("tcp-control-port")));
 564       dlTCP->go();
 565     }
 566
 567     // reparse, with error checking
 568     if(!::arg().mustDo("no-config"))
 569       ::arg().file(configname.c_str());
 570     ::arg().parse(argc,argv);
 571
 572     if(::arg()["server-id"].empty()) {
 573       char tmp[128];
 574       gethostname(tmp, sizeof(tmp)-1);
 575       ::arg().set("server-id")=tmp;
 576     }
 577
 578     UeberBackend::go();
 579     N=new UDPNameserver; // this fails when we are not root, throws exception
 580
 581     if(!::arg().mustDo("disable-tcp"))
 582       TN=new TCPNameserver;
 583   }
 584   catch(const ArgException &A) {
 585     L<<Logger::Error<<"Fatal error: "<<A.reason<<endl;
 586     exit(1);
 587   }
 588
 589   declareStats();
 590   DLOG(L<<Logger::Warning<<"Verbose logging in effect"<<endl);
 591
 592   showProductVersion();
 593
 594   try {
 595     mainthread();
 596   }
 597   catch(PDNSException &AE) {
 598     if(!::arg().mustDo("daemon"))
 599       cerr<<"Exiting because: "<<AE.reason<<endl;
 600     L<<Logger::Error<<"Exiting because: "<<AE.reason<<endl;
 601   }
 602   catch(std::exception &e) {
 603     if(!::arg().mustDo("daemon"))
 604       cerr<<"Exiting because of STL error: "<<e.what()<<endl;
 605     L<<Logger::Error<<"Exiting because of STL error: "<<e.what()<<endl;
 606   }
 607   catch(...) {
 608     cerr<<"Uncaught exception of unknown type - sorry"<<endl;
 609   }
 610
 611   exit(1);
 612
 613 }
 614
 615