pdns/dynlistener.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 <cstring>
  26 #include <string>
  27 #include <map>
  28 #include <sys/types.h>
  29 #include <sys/un.h>
  30 #include <dlfcn.h>
  31 #include <pthread.h>
  32 #include <unistd.h>
  33 #include <boost/algorithm/string.hpp>
  34
  35 #include <sys/socket.h>
  36 #include <netinet/in.h>
  37 #include <errno.h>
  38 #include <iostream>
  39 #include <sstream>
  40 #include <sys/types.h>
  41 #include <signal.h>
  42
  43 #include <sys/stat.h>
  44 #include <fcntl.h>
  45 #include <unistd.h>
  46 #include <boost/algorithm/string.hpp>
  47 #include "misc.hh"
  48 #include "dns.hh"
  49 #include "arguments.hh"
  50 #include "dnsbackend.hh"
  51 #include "dynlistener.hh"
  52 #include "dnspacket.hh"
  53 #include "logger.hh"
  54 #include "statbag.hh"
  55
  56 extern StatBag S;
  57
  58 DynListener::g_funkdb_t DynListener::s_funcdb;
  59 DynListener::g_funk_t* DynListener::s_restfunc;
  60
  61 DynListener::~DynListener()
  62 {
  63   if(!d_socketname.empty())
  64     unlink(d_socketname.c_str());
  65 }
  66
  67 void DynListener::createSocketAndBind(int family, struct sockaddr*local, size_t len)
  68 {
  69   d_s=socket(family, SOCK_STREAM,0);
  70   setCloseOnExec(d_s);
  71
  72   if(d_s < 0) {
  73     if (family == AF_UNIX)
  74       L<<Logger::Error<<"Unable to create control socket at '"<<((struct sockaddr_un*)local)->sun_path<<"', reason: "<<strerror(errno)<<endl;
  75     else
  76       L<<Logger::Error<<"Unable to create control socket on '"<<((ComboAddress *)local)->toStringWithPort()<<"', reason: "<<strerror(errno)<<endl;
  77     exit(1);
  78   }
  79
  80   int tmp=1;
  81   if(setsockopt(d_s,SOL_SOCKET,SO_REUSEADDR,(char*)&tmp,sizeof tmp)<0)
  82     throw PDNSException(string("Setsockopt failed on control socket: ")+strerror(errno));
  83
  84   if(bind(d_s, local, len) < 0) {
  85     if (family == AF_UNIX)
  86       L<<Logger::Critical<<"Unable to bind to control socket at '"<<((struct sockaddr_un*)local)->sun_path<<"', reason: "<<strerror(errno)<<endl;
  87     else
  88       L<<Logger::Critical<<"Unable to bind to control socket on '"<<((ComboAddress *)local)->toStringWithPort()<<"', reason: "<<strerror(errno)<<endl;
  89     exit(1);
  90   }
  91 }
  92
  93 /* this does a simplistic check, if we can connect, we consider it live. If we can't connect because
  94    of access denied, we must consider it dead, nothing we can do about it.
  95 */
  96 bool DynListener::testLive(const string& fname)
  97 {
  98   struct sockaddr_un addr;
  99   int fd = socket(AF_UNIX, SOCK_STREAM, 0);
 100   if(fd < 0) { // we'll have bigger issues down the road
 101     return false;
 102   }
 103
 104   if (makeUNsockaddr(fname, &addr)) {
 105     L<<Logger::Critical<<"Unable to open controlsocket, path '"<<fname<<"' is not a valid UNIX socket path."<<endl;
 106     exit(1);
 107   }
 108
 109   int status = connect(fd, (struct sockaddr*)&addr, sizeof(addr));
 110   close(fd);
 111   return status==0;
 112 }
 113
 114 void DynListener::listenOnUnixDomain(const string& fname)
 115 {
 116   if(testLive(fname)) {
 117     L<<Logger::Critical<<"Previous controlsocket '"<<fname<<"' is in use"<<endl;
 118     exit(1);
 119   }
 120   int err=unlink(fname.c_str());
 121   if(err < 0 && errno!=ENOENT) {
 122     L<<Logger::Critical<<"Unable to remove (previous) controlsocket at '"<<fname<<"': "<<strerror(errno)<<endl;
 123     exit(1);
 124   }
 125
 126   struct sockaddr_un local;
 127   if (makeUNsockaddr(fname, &local)) {
 128     L<<Logger::Critical<<"Unable to bind to controlsocket, path '"<<fname<<"' is not a valid UNIX socket path."<<endl;
 129     exit(1);
 130   }
 131
 132   createSocketAndBind(AF_UNIX, (struct sockaddr*)& local, sizeof(local));
 133   d_socketname=fname;
 134   if(!arg()["setgid"].empty()) {
 135     if(chmod(fname.c_str(),0660)<0)
 136       L<<Logger::Error<<"Unable to change group access mode of controlsocket at '"<<fname<<"', reason: "<<strerror(errno)<<endl;
 137     if(chown(fname.c_str(),static_cast<uid_t>(-1),Utility::makeGidNumeric(arg()["setgid"]))<0)
 138       L<<Logger::Error<<"Unable to change group ownership of controlsocket at '"<<fname<<"', reason: "<<strerror(errno)<<endl;
 139   }
 140
 141   listen(d_s, 10);
 142
 143   L<<Logger::Warning<<"Listening on controlsocket in '"<<fname<<"'"<<endl;
 144   d_nonlocal=true;
 145 }
 146
 147 void DynListener::listenOnTCP(const ComboAddress& local)
 148 {
 149   if (local.isIPv4()) {
 150     createSocketAndBind(AF_INET, (struct sockaddr*)& local, local.getSocklen());
 151   } else if (local.isIPv6()) {
 152     createSocketAndBind(AF_INET6, (struct sockaddr*)& local, local.getSocklen());
 153   }
 154   listen(d_s, 10);
 155
 156   d_socketaddress=local;
 157   L<<Logger::Warning<<"Listening on controlsocket on '"<<local.toStringWithPort()<<"'"<<endl;
 158   d_nonlocal=true;
 159
 160   if(!::arg()["tcp-control-range"].empty()) {
 161     d_tcprange.toMasks(::arg()["tcp-control-range"]);
 162     L<<Logger::Warning<<"Only allowing TCP control from: "<<d_tcprange.toString()<<endl;
 163   }
 164 }
 165
 166
 167 DynListener::DynListener(const ComboAddress& local)
 168 {
 169   listenOnTCP(local);
 170   d_tcp=true;
 171   d_client=-1;
 172   d_tid=0;
 173   d_ppid=0;
 174 }
 175
 176 DynListener::DynListener(const string &progname)
 177 {
 178   d_client=-1;
 179   d_tid=0;
 180   d_ppid=0;
 181   d_s=-1;
 182
 183   if(!progname.empty()) {
 184     string socketname = ::arg()["socket-dir"];
 185     if (::arg()["socket-dir"].empty()) {
 186       if (::arg()["chroot"].empty())
 187         socketname = LOCALSTATEDIR;
 188       else
 189         socketname = ::arg()["chroot"];
 190     } else if (!::arg()["socket-dir"].empty() && !::arg()["chroot"].empty()) {
 191       socketname = ::arg()["chroot"] + ::arg()["socket-dir"];
 192     }
 193     socketname += "/";
 194     cleanSlashes(socketname);
 195
 196     if(!mkdir(socketname.c_str(),0700)) // make /var directory, if needed
 197       L<<Logger::Warning<<"Created local state directory '"<<socketname<<"'"<<endl;
 198     else if(errno!=EEXIST) {
 199       L<<Logger::Critical<<"Unable to create socket directory ("<<socketname<<") and it does not exist yet"<<endl;
 200       exit(1);
 201     }
 202
 203     socketname+=progname+".controlsocket";
 204     listenOnUnixDomain(socketname);
 205   }
 206   else
 207     d_nonlocal=false; // we listen on stdin!
 208   d_tcp=false;
 209 }
 210
 211 void DynListener::go()
 212 {
 213   d_ppid=getpid();
 214   pthread_create(&d_tid,0,&DynListener::theListenerHelper,this);
 215 }
 216
 217 void *DynListener::theListenerHelper(void *p)
 218 {
 219   DynListener *us=static_cast<DynListener *>(p);
 220   us->theListener();
 221   L<<Logger::Error<<"Control listener aborted, please file a bug!"<<endl;
 222   return 0;
 223 }
 224
 225 string DynListener::getLine()
 226 {
 227   vector<char> mesg;
 228   mesg.resize(1024000);
 229
 230   int len;
 231
 232   ComboAddress remote;
 233   socklen_t remlen=remote.getSocklen();
 234
 235   if(d_nonlocal) {
 236     for(;;) {
 237       d_client=accept(d_s,(sockaddr*)&remote,&remlen);
 238       if(d_client<0) {
 239         if(errno!=EINTR)
 240           L<<Logger::Error<<"Unable to accept controlsocket connection ("<<d_s<<"): "<<strerror(errno)<<endl;
 241         continue;
 242       }
 243
 244       if(d_tcp && !d_tcprange.match(&remote)) { // checks if the remote is within the permitted range.
 245         L<<Logger::Error<<"Access denied to remote "<<remote.toString()<<" because not allowed"<<endl;
 246         writen2(d_client, "Access denied to "+remote.toString()+"\n");
 247         close(d_client);
 248         continue;
 249       }
 250
 251       std::shared_ptr<FILE> fp=std::shared_ptr<FILE>(fdopen(dup(d_client), "r"), fclose);
 252       if(d_tcp) {
 253         if(!fgets(&mesg[0], mesg.size(), fp.get())) {
 254           L<<Logger::Error<<"Unable to receive password from controlsocket ("<<d_client<<"): "<<strerror(errno)<<endl;
 255           close(d_client);
 256           continue;
 257         }
 258         string password(&mesg[0]);
 259         boost::trim(password);
 260         if(password.empty() || password!=arg()["tcp-control-secret"]) {
 261           L<<Logger::Error<<"Wrong password on TCP control socket"<<endl;
 262           writen2(d_client, "Wrong password");
 263
 264           close(d_client);
 265           continue;
 266         }
 267       }
 268       errno=0;
 269       if(!fgets(&mesg[0], mesg.size(), fp.get())) {
 270         if(errno)
 271           L<<Logger::Error<<"Unable to receive line from controlsocket ("<<d_client<<"): "<<strerror(errno)<<endl;
 272         close(d_client);
 273         continue;
 274       }
 275
 276       if(strlen(&mesg[0]) == mesg.size()) {
 277         L<<Logger::Error<<"Line on controlsocket ("<<d_client<<") was too long"<<endl;
 278         close(d_client);
 279         continue;
 280       }
 281       break;
 282     }
 283   }
 284   else {
 285     if(isatty(0))
 286       if(write(1, "% ", 2) !=2)
 287         throw PDNSException("Writing to console: "+stringerror());
 288     if((len=read(0, &mesg[0], mesg.size())) < 0)
 289       throw PDNSException("Reading from the control pipe: "+stringerror());
 290     else if(len==0)
 291       throw PDNSException("Guardian exited - going down as well");
 292
 293     if(len == (int)mesg.size())
 294       throw PDNSException("Line on control console was too long");
 295
 296     mesg[len]=0;
 297   }
 298
 299   return &mesg[0];
 300 }
 301
 302 void DynListener::sendlines(const string &l)
 303 {
 304   if(d_nonlocal) {
 305     unsigned int sent=0;
 306     int ret;
 307     while(sent < l.length()) {
 308       ret=send(d_client, l.c_str()+sent, l.length()-sent, 0);
 309
 310       if(ret<0 || !ret) {
 311         L<<Logger::Error<<"Error sending data to pdns_control: "<<stringerror()<<endl;
 312         break;
 313       }
 314       sent+=ret;
 315     }
 316     close(d_client);
 317   } else {
 318     string lines=l;
 319     if(!lines.empty() && lines[lines.length()-1] != '\n')
 320       lines.append("\n");
 321     lines.append(1, '\0');
 322     lines.append(1, '\n');
 323     if((unsigned int)write(1, lines.c_str(), lines.length()) != lines.length())
 324       L<<Logger::Error<<"Error sending data to console: "<<stringerror()<<endl;
 325   }
 326 }
 327
 328 void DynListener::registerFunc(const string &name, g_funk_t *gf, const string &usage, const string &args)
 329 {
 330   g_funkwithusage_t e = {gf, args, usage};
 331   s_funcdb[name]=e;
 332 }
 333
 334 void DynListener::registerRestFunc(g_funk_t *gf)
 335 {
 336   s_restfunc=gf;
 337 }
 338
 339 void DynListener::theListener()
 340 {
 341   try {
 342     signal(SIGPIPE,SIG_IGN);
 343
 344     for(int n=0;;++n) {
 345       string line=getLine();
 346       boost::trim_right(line);
 347
 348       vector<string>parts;
 349       stringtok(parts,line," ");
 350       if(parts.empty()) {
 351         sendlines("Empty line");
 352         continue;
 353       }
 354
 355       try {
 356         parts[0] = toUpper( parts[0] );
 357         if(s_funcdb.count(parts[0]))
 358           sendlines((*(s_funcdb[parts[0]].func))(parts,d_ppid));
 359         else if (parts[0] == "HELP")
 360           sendlines(getHelp());
 361         else if(s_restfunc)
 362           sendlines((*s_restfunc)(parts,d_ppid));
 363         else
 364           sendlines("Unknown command: '"+parts[0]+"'");
 365       }
 366       catch(PDNSException &AE) {
 367         L<<Logger::Error<<"Non-fatal error in control listener command '"<<line<<"': "<<AE.reason<<endl;
 368       }
 369       catch(string &E) {
 370         L<<Logger::Error<<"Non-fatal error 2 in control listener command '"<<line<<"': "<<E<<endl;
 371       }
 372       catch(std::exception& e) {
 373         L<<Logger::Error<<"Non-fatal STL error in control listener command '"<<line<<"': "<<e.what()<<endl;
 374       }
 375       catch(...) {
 376         L<<Logger::Error<<"Non-fatal error in control listener command '"<<line<<"': unknown exception occurred"<<endl;
 377       }
 378     }
 379   }
 380   catch(PDNSException &AE) {
 381     L<<Logger::Error<<"Fatal error in control listener: "<<AE.reason<<endl;
 382   }
 383   catch(string &E) {
 384     L<<Logger::Error<<"Fatal error 2 in control listener: "<<E<<endl;
 385   }
 386   catch(std::exception& e) {
 387     L<<Logger::Error<<"Fatal STL error in control listener: "<<e.what()<<endl;
 388   }
 389   catch(...) {
 390     L<<Logger::Error<<"Fatal: unknown exception in control listener occurred"<<endl;
 391   }
 392 }
 393
 394
 395 string DynListener::getHelp()
 396 {
 397   vector<string> funcs;
 398   string rest;
 399
 400   // s_restfunc, when in guardian mode, is the function that
 401   // can pass commands on to the guarded instance
 402   // we just pass it HELP and merge it with our own list
 403   if(s_restfunc)
 404   {
 405     vector<string> parts;
 406     parts.push_back("HELP");
 407     rest=((*s_restfunc)(parts,d_ppid));
 408     boost::split(funcs, rest, boost::is_any_of("\n"));
 409   }
 410
 411   const boost::format fmter("%|-32| %||");
 412
 413   for(g_funkdb_t::const_iterator i=s_funcdb.begin();i!=s_funcdb.end();++i) {
 414     funcs.push_back(str(boost::format(fmter) % (toLower(i->first)+" "+i->second.args) % i->second.usage));
 415   }
 416   sort(funcs.begin(), funcs.end());
 417
 418   // hack: this removes the duplicate quit method
 419   funcs.resize(unique(funcs.begin(), funcs.end()) - funcs.begin());
 420   return boost::join(funcs, "\n");
 421 }