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 #include "threadname.hh"
  56
  57 extern StatBag S;
  58
  59 DynListener::g_funkdb_t DynListener::s_funcdb;
  60 DynListener::g_funk_t* DynListener::s_restfunc;
  61
  62 DynListener::~DynListener()
  63 {
  64   if(!d_socketname.empty())
  65     unlink(d_socketname.c_str());
  66 }
  67
  68 void DynListener::createSocketAndBind(int family, struct sockaddr*local, size_t len)
  69 {
  70   d_s=socket(family, SOCK_STREAM,0);
  71   setCloseOnExec(d_s);
  72
  73   if(d_s < 0) {
  74     if (family == AF_UNIX)
  75       g_log<<Logger::Error<<"Unable to create control socket at '"<<((struct sockaddr_un*)local)->sun_path<<"', reason: "<<strerror(errno)<<endl;
  76     else
  77       g_log<<Logger::Error<<"Unable to create control socket on '"<<((ComboAddress *)local)->toStringWithPort()<<"', reason: "<<strerror(errno)<<endl;
  78     exit(1);
  79   }
  80
  81   int tmp=1;
  82   if(setsockopt(d_s,SOL_SOCKET,SO_REUSEADDR,(char*)&tmp,sizeof tmp)<0)
  83     throw PDNSException(string("Setsockopt failed on control socket: ")+strerror(errno));
  84
  85   if(bind(d_s, local, len) < 0) {
  86     if (family == AF_UNIX)
  87       g_log<<Logger::Critical<<"Unable to bind to control socket at '"<<((struct sockaddr_un*)local)->sun_path<<"', reason: "<<strerror(errno)<<endl;
  88     else
  89       g_log<<Logger::Critical<<"Unable to bind to control socket on '"<<((ComboAddress *)local)->toStringWithPort()<<"', reason: "<<strerror(errno)<<endl;
  90     exit(1);
  91   }
  92 }
  93
  94 /* this does a simplistic check, if we can connect, we consider it live. If we can't connect because
  95    of access denied, we must consider it dead, nothing we can do about it.
  96 */
  97 bool DynListener::testLive(const string& fname)
  98 {
  99   struct sockaddr_un addr;
 100   int fd = socket(AF_UNIX, SOCK_STREAM, 0);
 101   if(fd < 0) { // we'll have bigger issues down the road
 102     return false;
 103   }
 104
 105   if (makeUNsockaddr(fname, &addr)) {
 106     g_log<<Logger::Critical<<"Unable to open controlsocket, path '"<<fname<<"' is not a valid UNIX socket path."<<endl;
 107     exit(1);
 108   }
 109
 110   int status = connect(fd, (struct sockaddr*)&addr, sizeof(addr));
 111   close(fd);
 112   return status==0;
 113 }
 114
 115 void DynListener::listenOnUnixDomain(const string& fname)
 116 {
 117   if(testLive(fname)) {
 118     g_log<<Logger::Critical<<"Previous controlsocket '"<<fname<<"' is in use"<<endl;
 119     exit(1);
 120   }
 121   int err=unlink(fname.c_str());
 122   if(err < 0 && errno!=ENOENT) {
 123     g_log<<Logger::Critical<<"Unable to remove (previous) controlsocket at '"<<fname<<"': "<<strerror(errno)<<endl;
 124     exit(1);
 125   }
 126
 127   struct sockaddr_un local;
 128   if (makeUNsockaddr(fname, &local)) {
 129     g_log<<Logger::Critical<<"Unable to bind to controlsocket, path '"<<fname<<"' is not a valid UNIX socket path."<<endl;
 130     exit(1);
 131   }
 132
 133   createSocketAndBind(AF_UNIX, (struct sockaddr*)& local, sizeof(local));
 134   d_socketname=fname;
 135   if(!arg()["setgid"].empty()) {
 136     if(chmod(fname.c_str(),0660)<0)
 137       g_log<<Logger::Error<<"Unable to change group access mode of controlsocket at '"<<fname<<"', reason: "<<strerror(errno)<<endl;
 138     if(chown(fname.c_str(),static_cast<uid_t>(-1),Utility::makeGidNumeric(arg()["setgid"]))<0)
 139       g_log<<Logger::Error<<"Unable to change group ownership of controlsocket at '"<<fname<<"', reason: "<<strerror(errno)<<endl;
 140   }
 141
 142   listen(d_s, 10);
 143
 144   g_log<<Logger::Warning<<"Listening on controlsocket in '"<<fname<<"'"<<endl;
 145   d_nonlocal=true;
 146 }
 147
 148 void DynListener::listenOnTCP(const ComboAddress& local)
 149 {
 150   if (local.isIPv4()) {
 151     createSocketAndBind(AF_INET, (struct sockaddr*)& local, local.getSocklen());
 152   } else if (local.isIPv6()) {
 153     createSocketAndBind(AF_INET6, (struct sockaddr*)& local, local.getSocklen());
 154   }
 155   listen(d_s, 10);
 156
 157   d_socketaddress=local;
 158   g_log<<Logger::Warning<<"Listening on controlsocket on '"<<local.toStringWithPort()<<"'"<<endl;
 159   d_nonlocal=true;
 160
 161   if(!::arg()["tcp-control-range"].empty()) {
 162     d_tcprange.toMasks(::arg()["tcp-control-range"]);
 163     g_log<<Logger::Warning<<"Only allowing TCP control from: "<<d_tcprange.toString()<<endl;
 164   }
 165 }
 166
 167
 168 DynListener::DynListener(const ComboAddress& local)
 169 {
 170   listenOnTCP(local);
 171   d_tcp=true;
 172   d_client=-1;
 173   d_tid=0;
 174   d_ppid=0;
 175 }
 176
 177 DynListener::DynListener(const string &progname)
 178 {
 179   d_client=-1;
 180   d_tid=0;
 181   d_ppid=0;
 182   d_s=-1;
 183
 184   if(!progname.empty()) {
 185     string socketname = ::arg()["socket-dir"];
 186     if (::arg()["socket-dir"].empty()) {
 187       if (::arg()["chroot"].empty())
 188         socketname = LOCALSTATEDIR;
 189       else
 190         socketname = ::arg()["chroot"];
 191     } else if (!::arg()["socket-dir"].empty() && !::arg()["chroot"].empty()) {
 192       socketname = ::arg()["chroot"] + ::arg()["socket-dir"];
 193     }
 194     socketname += "/";
 195     cleanSlashes(socketname);
 196
 197     if(!mkdir(socketname.c_str(),0700)) // make /var directory, if needed
 198       g_log<<Logger::Warning<<"Created local state directory '"<<socketname<<"'"<<endl;
 199     else if(errno!=EEXIST) {
 200       g_log<<Logger::Critical<<"Unable to create socket directory ("<<socketname<<") and it does not exist yet"<<endl;
 201       exit(1);
 202     }
 203
 204     socketname+=progname+".controlsocket";
 205     listenOnUnixDomain(socketname);
 206   }
 207   else
 208     d_nonlocal=false; // we listen on stdin!
 209   d_tcp=false;
 210 }
 211
 212 void DynListener::go()
 213 {
 214   d_ppid=getpid();
 215   pthread_create(&d_tid,0,&DynListener::theListenerHelper,this);
 216 }
 217
 218 void *DynListener::theListenerHelper(void *p)
 219 {
 220   setThreadName("pdns/ctrlListen");
 221   DynListener *us=static_cast<DynListener *>(p);
 222   us->theListener();
 223   g_log<<Logger::Error<<"Control listener aborted, please file a bug!"<<endl;
 224   return 0;
 225 }
 226
 227 string DynListener::getLine()
 228 {
 229   vector<char> mesg;
 230   mesg.resize(1024000);
 231
 232   int len;
 233
 234   ComboAddress remote;
 235   socklen_t remlen=remote.getSocklen();
 236
 237   if(d_nonlocal) {
 238     for(;;) {
 239       d_client=accept(d_s,(sockaddr*)&remote,&remlen);
 240       if(d_client<0) {
 241         if(errno!=EINTR)
 242           g_log<<Logger::Error<<"Unable to accept controlsocket connection ("<<d_s<<"): "<<strerror(errno)<<endl;
 243         continue;
 244       }
 245
 246       if(d_tcp && !d_tcprange.match(&remote)) { // checks if the remote is within the permitted range.
 247         g_log<<Logger::Error<<"Access denied to remote "<<remote.toString()<<" because not allowed"<<endl;
 248         writen2(d_client, "Access denied to "+remote.toString()+"\n");
 249         close(d_client);
 250         continue;
 251       }
 252
 253       std::shared_ptr<FILE> fp=std::shared_ptr<FILE>(fdopen(dup(d_client), "r"), fclose);
 254       if(d_tcp) {
 255         if(!fgets(&mesg[0], mesg.size(), fp.get())) {
 256           g_log<<Logger::Error<<"Unable to receive password from controlsocket ("<<d_client<<"): "<<strerror(errno)<<endl;
 257           close(d_client);
 258           continue;
 259         }
 260         string password(&mesg[0]);
 261         boost::trim(password);
 262         if(password.empty() || password!=arg()["tcp-control-secret"]) {
 263           g_log<<Logger::Error<<"Wrong password on TCP control socket"<<endl;
 264           writen2(d_client, "Wrong password");
 265
 266           close(d_client);
 267           continue;
 268         }
 269       }
 270       errno=0;
 271       if(!fgets(&mesg[0], mesg.size(), fp.get())) {
 272         if(errno)
 273           g_log<<Logger::Error<<"Unable to receive line from controlsocket ("<<d_client<<"): "<<strerror(errno)<<endl;
 274         close(d_client);
 275         continue;
 276       }
 277
 278       if(strlen(&mesg[0]) == mesg.size()) {
 279         g_log<<Logger::Error<<"Line on controlsocket ("<<d_client<<") was too long"<<endl;
 280         close(d_client);
 281         continue;
 282       }
 283       break;
 284     }
 285   }
 286   else {
 287     if(isatty(0))
 288       if(write(1, "% ", 2) !=2)
 289         throw PDNSException("Writing to console: "+stringerror());
 290     if((len=read(0, &mesg[0], mesg.size())) < 0)
 291       throw PDNSException("Reading from the control pipe: "+stringerror());
 292     else if(len==0)
 293       throw PDNSException("Guardian exited - going down as well");
 294
 295     if(len == (int)mesg.size())
 296       throw PDNSException("Line on control console was too long");
 297
 298     mesg[len]=0;
 299   }
 300
 301   return &mesg[0];
 302 }
 303
 304 void DynListener::sendlines(const string &l)
 305 {
 306   if(d_nonlocal) {
 307     unsigned int sent=0;
 308     int ret;
 309     while(sent < l.length()) {
 310       ret=send(d_client, l.c_str()+sent, l.length()-sent, 0);
 311
 312       if(ret<0 || !ret) {
 313         g_log<<Logger::Error<<"Error sending data to pdns_control: "<<stringerror()<<endl;
 314         break;
 315       }
 316       sent+=ret;
 317     }
 318     close(d_client);
 319   } else {
 320     string lines=l;
 321     if(!lines.empty() && lines[lines.length()-1] != '\n')
 322       lines.append("\n");
 323     lines.append(1, '\0');
 324     lines.append(1, '\n');
 325     if((unsigned int)write(1, lines.c_str(), lines.length()) != lines.length())
 326       g_log<<Logger::Error<<"Error sending data to console: "<<stringerror()<<endl;
 327   }
 328 }
 329
 330 void DynListener::registerFunc(const string &name, g_funk_t *gf, const string &usage, const string &args)
 331 {
 332   g_funkwithusage_t e = {gf, args, usage};
 333   s_funcdb[name]=e;
 334 }
 335
 336 void DynListener::registerRestFunc(g_funk_t *gf)
 337 {
 338   s_restfunc=gf;
 339 }
 340
 341 void DynListener::theListener()
 342 {
 343   try {
 344     signal(SIGPIPE,SIG_IGN);
 345
 346     for(int n=0;;++n) {
 347       string line=getLine();
 348       boost::trim_right(line);
 349
 350       vector<string>parts;
 351       stringtok(parts,line," ");
 352       if(parts.empty()) {
 353         sendlines("Empty line");
 354         continue;
 355       }
 356
 357       try {
 358         parts[0] = toUpper( parts[0] );
 359         if(s_funcdb.count(parts[0]))
 360           sendlines((*(s_funcdb[parts[0]].func))(parts,d_ppid));
 361         else if (parts[0] == "HELP")
 362           sendlines(getHelp());
 363         else if(s_restfunc)
 364           sendlines((*s_restfunc)(parts,d_ppid));
 365         else
 366           sendlines("Unknown command: '"+parts[0]+"'");
 367       }
 368       catch(PDNSException &AE) {
 369         g_log<<Logger::Error<<"Non-fatal error in control listener command '"<<line<<"': "<<AE.reason<<endl;
 370       }
 371       catch(string &E) {
 372         g_log<<Logger::Error<<"Non-fatal error 2 in control listener command '"<<line<<"': "<<E<<endl;
 373       }
 374       catch(std::exception& e) {
 375         g_log<<Logger::Error<<"Non-fatal STL error in control listener command '"<<line<<"': "<<e.what()<<endl;
 376       }
 377       catch(...) {
 378         g_log<<Logger::Error<<"Non-fatal error in control listener command '"<<line<<"': unknown exception occurred"<<endl;
 379       }
 380     }
 381   }
 382   catch(PDNSException &AE) {
 383     g_log<<Logger::Error<<"Fatal error in control listener: "<<AE.reason<<endl;
 384   }
 385   catch(string &E) {
 386     g_log<<Logger::Error<<"Fatal error 2 in control listener: "<<E<<endl;
 387   }
 388   catch(std::exception& e) {
 389     g_log<<Logger::Error<<"Fatal STL error in control listener: "<<e.what()<<endl;
 390   }
 391   catch(...) {
 392     g_log<<Logger::Error<<"Fatal: unknown exception in control listener occurred"<<endl;
 393   }
 394 }
 395
 396
 397 string DynListener::getHelp()
 398 {
 399   vector<string> funcs;
 400   string rest;
 401
 402   // s_restfunc, when in guardian mode, is the function that
 403   // can pass commands on to the guarded instance
 404   // we just pass it HELP and merge it with our own list
 405   if(s_restfunc)
 406   {
 407     vector<string> parts;
 408     parts.push_back("HELP");
 409     rest=((*s_restfunc)(parts,d_ppid));
 410     boost::split(funcs, rest, boost::is_any_of("\n"));
 411   }
 412
 413   const boost::format fmter("%|-32| %||");
 414
 415   for(g_funkdb_t::const_iterator i=s_funcdb.begin();i!=s_funcdb.end();++i) {
 416     funcs.push_back(str(boost::format(fmter) % (toLower(i->first)+" "+i->second.args) % i->second.usage));
 417   }
 418   sort(funcs.begin(), funcs.end());
 419
 420   // hack: this removes the duplicate quit method
 421   funcs.resize(unique(funcs.begin(), funcs.end()) - funcs.begin());
 422   return boost::join(funcs, "\n");
 423 }