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   d_tcp(true)
 170 {
 171   listenOnTCP(local);
 172 }
 173
 174 DynListener::DynListener(const string &progname)
 175 {
 176
 177   if(!progname.empty()) {
 178     string socketname = ::arg()["socket-dir"];
 179     if (::arg()["socket-dir"].empty()) {
 180       if (::arg()["chroot"].empty())
 181         socketname = LOCALSTATEDIR;
 182       else
 183         socketname = ::arg()["chroot"];
 184     } else if (!::arg()["socket-dir"].empty() && !::arg()["chroot"].empty()) {
 185       socketname = ::arg()["chroot"] + ::arg()["socket-dir"];
 186     }
 187     socketname += "/";
 188     cleanSlashes(socketname);
 189
 190     if(!mkdir(socketname.c_str(),0700)) // make /var directory, if needed
 191       g_log<<Logger::Warning<<"Created local state directory '"<<socketname<<"'"<<endl;
 192     else if(errno!=EEXIST) {
 193       g_log<<Logger::Critical<<"Unable to create socket directory ("<<socketname<<") and it does not exist yet"<<endl;
 194       exit(1);
 195     }
 196
 197     socketname+=progname+".controlsocket";
 198     listenOnUnixDomain(socketname);
 199   }
 200   else
 201     d_nonlocal=false; // we listen on stdin!
 202 }
 203
 204 void DynListener::go()
 205 {
 206   d_ppid=getpid();
 207   pthread_create(&d_tid,0,&DynListener::theListenerHelper,this);
 208 }
 209
 210 void *DynListener::theListenerHelper(void *p)
 211 {
 212   setThreadName("pdns/ctrlListen");
 213   DynListener *us=static_cast<DynListener *>(p);
 214   us->theListener();
 215   g_log<<Logger::Error<<"Control listener aborted, please file a bug!"<<endl;
 216   return 0;
 217 }
 218
 219 string DynListener::getLine()
 220 {
 221   vector<char> mesg;
 222   mesg.resize(1024000);
 223
 224   int len;
 225
 226   ComboAddress remote;
 227   socklen_t remlen=remote.getSocklen();
 228
 229   if(d_nonlocal) {
 230     for(;;) {
 231       d_client=accept(d_s,(sockaddr*)&remote,&remlen);
 232       if(d_client<0) {
 233         if(errno!=EINTR)
 234           g_log<<Logger::Error<<"Unable to accept controlsocket connection ("<<d_s<<"): "<<strerror(errno)<<endl;
 235         continue;
 236       }
 237
 238       if(d_tcp && !d_tcprange.match(&remote)) { // checks if the remote is within the permitted range.
 239         g_log<<Logger::Error<<"Access denied to remote "<<remote.toString()<<" because not allowed"<<endl;
 240         writen2(d_client, "Access denied to "+remote.toString()+"\n");
 241         close(d_client);
 242         continue;
 243       }
 244
 245       std::shared_ptr<FILE> fp=std::shared_ptr<FILE>(fdopen(dup(d_client), "r"), fclose);
 246       if(d_tcp) {
 247         if(!fgets(&mesg[0], mesg.size(), fp.get())) {
 248           g_log<<Logger::Error<<"Unable to receive password from controlsocket ("<<d_client<<"): "<<strerror(errno)<<endl;
 249           close(d_client);
 250           continue;
 251         }
 252         string password(&mesg[0]);
 253         boost::trim(password);
 254         if(password.empty() || password!=arg()["tcp-control-secret"]) {
 255           g_log<<Logger::Error<<"Wrong password on TCP control socket"<<endl;
 256           writen2(d_client, "Wrong password");
 257
 258           close(d_client);
 259           continue;
 260         }
 261       }
 262       errno=0;
 263       if(!fgets(&mesg[0], mesg.size(), fp.get())) {
 264         if(errno)
 265           g_log<<Logger::Error<<"Unable to receive line from controlsocket ("<<d_client<<"): "<<strerror(errno)<<endl;
 266         close(d_client);
 267         continue;
 268       }
 269
 270       if(strlen(&mesg[0]) == mesg.size()) {
 271         g_log<<Logger::Error<<"Line on controlsocket ("<<d_client<<") was too long"<<endl;
 272         close(d_client);
 273         continue;
 274       }
 275       break;
 276     }
 277   }
 278   else {
 279     if(isatty(0))
 280       if(write(1, "% ", 2) !=2)
 281         throw PDNSException("Writing to console: "+stringerror());
 282     if((len=read(0, &mesg[0], mesg.size())) < 0)
 283       throw PDNSException("Reading from the control pipe: "+stringerror());
 284     else if(len==0)
 285       throw PDNSException("Guardian exited - going down as well");
 286
 287     if(len == (int)mesg.size())
 288       throw PDNSException("Line on control console was too long");
 289
 290     mesg[len]=0;
 291   }
 292
 293   return &mesg[0];
 294 }
 295
 296 void DynListener::sendlines(const string &l)
 297 {
 298   if(d_nonlocal) {
 299     unsigned int sent=0;
 300     int ret;
 301     while(sent < l.length()) {
 302       ret=send(d_client, l.c_str()+sent, l.length()-sent, 0);
 303
 304       if(ret<0 || !ret) {
 305         g_log<<Logger::Error<<"Error sending data to pdns_control: "<<stringerror()<<endl;
 306         break;
 307       }
 308       sent+=ret;
 309     }
 310     close(d_client);
 311   } else {
 312     string lines=l;
 313     if(!lines.empty() && lines[lines.length()-1] != '\n')
 314       lines.append("\n");
 315     lines.append(1, '\0');
 316     lines.append(1, '\n');
 317     if((unsigned int)write(1, lines.c_str(), lines.length()) != lines.length())
 318       g_log<<Logger::Error<<"Error sending data to console: "<<stringerror()<<endl;
 319   }
 320 }
 321
 322 void DynListener::registerFunc(const string &name, g_funk_t *gf, const string &usage, const string &args)
 323 {
 324   g_funkwithusage_t e = {gf, args, usage};
 325   s_funcdb[name]=e;
 326 }
 327
 328 void DynListener::registerRestFunc(g_funk_t *gf)
 329 {
 330   s_restfunc=gf;
 331 }
 332
 333 void DynListener::theListener()
 334 {
 335   try {
 336     signal(SIGPIPE,SIG_IGN);
 337
 338     for(int n=0;;++n) {
 339       string line=getLine();
 340       boost::trim_right(line);
 341
 342       vector<string>parts;
 343       stringtok(parts,line," ");
 344       if(parts.empty()) {
 345         sendlines("Empty line");
 346         continue;
 347       }
 348
 349       try {
 350         parts[0] = toUpper( parts[0] );
 351         if(s_funcdb.count(parts[0]))
 352           sendlines((*(s_funcdb[parts[0]].func))(parts,d_ppid));
 353         else if (parts[0] == "HELP")
 354           sendlines(getHelp());
 355         else if(s_restfunc)
 356           sendlines((*s_restfunc)(parts,d_ppid));
 357         else
 358           sendlines("Unknown command: '"+parts[0]+"'");
 359       }
 360       catch(PDNSException &AE) {
 361         g_log<<Logger::Error<<"Non-fatal error in control listener command '"<<line<<"': "<<AE.reason<<endl;
 362       }
 363       catch(string &E) {
 364         g_log<<Logger::Error<<"Non-fatal error 2 in control listener command '"<<line<<"': "<<E<<endl;
 365       }
 366       catch(std::exception& e) {
 367         g_log<<Logger::Error<<"Non-fatal STL error in control listener command '"<<line<<"': "<<e.what()<<endl;
 368       }
 369       catch(...) {
 370         g_log<<Logger::Error<<"Non-fatal error in control listener command '"<<line<<"': unknown exception occurred"<<endl;
 371       }
 372     }
 373   }
 374   catch(PDNSException &AE) {
 375     g_log<<Logger::Error<<"Fatal error in control listener: "<<AE.reason<<endl;
 376   }
 377   catch(string &E) {
 378     g_log<<Logger::Error<<"Fatal error 2 in control listener: "<<E<<endl;
 379   }
 380   catch(std::exception& e) {
 381     g_log<<Logger::Error<<"Fatal STL error in control listener: "<<e.what()<<endl;
 382   }
 383   catch(...) {
 384     g_log<<Logger::Error<<"Fatal: unknown exception in control listener occurred"<<endl;
 385   }
 386 }
 387
 388
 389 string DynListener::getHelp()
 390 {
 391   vector<string> funcs;
 392   string rest;
 393
 394   // s_restfunc, when in guardian mode, is the function that
 395   // can pass commands on to the guarded instance
 396   // we just pass it HELP and merge it with our own list
 397   if(s_restfunc)
 398   {
 399     vector<string> parts;
 400     parts.push_back("HELP");
 401     rest=((*s_restfunc)(parts,d_ppid));
 402     boost::split(funcs, rest, boost::is_any_of("\n"));
 403   }
 404
 405   const boost::format fmter("%|-32| %||");
 406
 407   for(g_funkdb_t::const_iterator i=s_funcdb.begin();i!=s_funcdb.end();++i) {
 408     funcs.push_back(str(boost::format(fmter) % (toLower(i->first)+" "+i->second.args) % i->second.usage));
 409   }
 410   sort(funcs.begin(), funcs.end());
 411
 412   // hack: this removes the duplicate quit method
 413   funcs.resize(unique(funcs.begin(), funcs.end()) - funcs.begin());
 414   return boost::join(funcs, "\n");
 415 }