pdns/unix_utility.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 "utility.hh"
  26 #include <cstring>
  27 #include <fcntl.h>
  28 #include <unistd.h>
  29 #include <stdlib.h>
  30 #include "pdnsexception.hh"
  31 #include "logger.hh"
  32 #include "misc.hh"
  33 #include <pwd.h>
  34 #include <grp.h>
  35 #include <sys/types.h>
  36 #include <sys/select.h>
  37
  38 #ifdef NEED_INET_NTOP_PROTO
  39 extern "C" {
  40 const char *inet_ntop(int af, const void *src, char *dst, size_t cnt);
  41 }
  42 #endif
  43
  44
  45 #include "namespaces.hh"
  46
  47
  48 // Connects to socket with timeout
  49 int Utility::timed_connect( Utility::sock_t sock,
  50     const sockaddr *addr,
  51     Utility::socklen_t sockaddr_size,
  52     int timeout_sec,
  53     int timeout_usec )
  54 {
  55   fd_set set;
  56   struct timeval timeout;
  57   int ret;
  58
  59   timeout.tv_sec = timeout_sec;
  60   timeout.tv_usec = timeout_usec;
  61
  62   FD_ZERO(&set);
  63   FD_SET(sock, &set);
  64
  65   setNonBlocking(sock);
  66
  67   if ((ret = connect (sock, addr, sockaddr_size)) < 0) {
  68     if (errno != EINPROGRESS)
  69       return ret;
  70   }
  71
  72   ret = select(sock + 1, NULL, &set, NULL, &timeout);
  73   setBlocking(sock);
  74
  75   return ret;
  76 }
  77
  78
  79
  80 void Utility::setBindAny(int af, sock_t sock)
  81 {
  82   const int one = 1;
  83
  84   (void) one; // avoids 'unused var' warning on systems that have none of the defines checked below
  85 #ifdef IP_FREEBIND
  86   if (setsockopt(sock, IPPROTO_IP, IP_FREEBIND, &one, sizeof(one)) < 0)
  87       g_log<<Logger::Warning<<"Warning: IP_FREEBIND setsockopt failed: "<<strerror(errno)<<endl;
  88 #endif
  89
  90 #ifdef IP_BINDANY
  91   if (af == AF_INET)
  92     if (setsockopt(sock, IPPROTO_IP, IP_BINDANY, &one, sizeof(one)) < 0)
  93       g_log<<Logger::Warning<<"Warning: IP_BINDANY setsockopt failed: "<<strerror(errno)<<endl;
  94 #endif
  95 #ifdef IPV6_BINDANY
  96   if (af == AF_INET6)
  97     if (setsockopt(sock, IPPROTO_IPV6, IPV6_BINDANY, &one, sizeof(one)) < 0)
  98       g_log<<Logger::Warning<<"Warning: IPV6_BINDANY setsockopt failed: "<<strerror(errno)<<endl;
  99 #endif
 100 #ifdef SO_BINDANY
 101   if (setsockopt(sock, SOL_SOCKET, SO_BINDANY, &one, sizeof(one)) < 0)
 102       g_log<<Logger::Warning<<"Warning: SO_BINDANY setsockopt failed: "<<strerror(errno)<<endl;
 103 #endif
 104 }
 105
 106 const char *Utility::inet_ntop(int af, const char *src, char *dst, size_t size)
 107 {
 108   return ::inet_ntop(af,src,dst,size);
 109 }
 110
 111 unsigned int Utility::sleep(unsigned int sec)
 112 {
 113   return ::sleep(sec);
 114 }
 115
 116 void Utility::usleep(unsigned long usec)
 117 {
 118   struct timespec ts;
 119   ts.tv_sec = usec / 1000000;
 120   ts.tv_nsec = (usec % 1000000) * 1000;
 121   // POSIX.1 recommends using nanosleep instead of usleep
 122   ::nanosleep(&ts, NULL);
 123 }
 124
 125
 126 // Drops the program's group privileges.
 127 void Utility::dropGroupPrivs( uid_t uid, gid_t gid )
 128 {
 129   if(gid && gid != getegid()) {
 130     if(setgid(gid)<0) {
 131       g_log<<Logger::Critical<<"Unable to set effective group id to "<<gid<<": "<<stringerror()<<endl;
 132       exit(1);
 133     }
 134     else
 135       g_log<<Logger::Info<<"Set effective group id to "<<gid<<endl;
 136
 137     struct passwd *pw=getpwuid(uid);
 138     if(!pw) {
 139       g_log<<Logger::Warning<<"Unable to determine user name for uid "<<uid<<endl;
 140       if (setgroups(0, NULL)<0) {
 141         g_log<<Logger::Critical<<"Unable to drop supplementary gids: "<<stringerror()<<endl;
 142         exit(1);
 143       }
 144     } else {
 145       if (initgroups(pw->pw_name, gid)<0) {
 146         g_log<<Logger::Critical<<"Unable to set supplementary groups: "<<stringerror()<<endl;
 147         exit(1);
 148       }
 149     }
 150   }
 151 }
 152
 153
 154 // Drops the program's user privileges.
 155 void Utility::dropUserPrivs( uid_t uid )
 156 {
 157   if(uid && uid != geteuid()) {
 158     if(setuid(uid)<0) {
 159       g_log<<Logger::Critical<<"Unable to set effective user id to "<<uid<<": "<<stringerror()<<endl;
 160       exit(1);
 161     }
 162     else
 163       g_log<<Logger::Info<<"Set effective user id to "<<uid<<endl;
 164   }
 165 }
 166
 167
 168 // Returns the current process id.
 169 Utility::pid_t Utility::getpid( void )
 170 {
 171   return ::getpid();
 172 }
 173
 174
 175 // Returns the current time.
 176 int Utility::gettimeofday( struct timeval *tv, void *tz )
 177 {
 178   return ::gettimeofday(tv,0);
 179 }
 180
 181
 182
 183 // Retrieves a gid using a groupname.
 184 gid_t Utility::makeGidNumeric(const string &group)
 185 {
 186   gid_t newgid;
 187   if(!(newgid=atoi(group.c_str()))) {
 188     errno=0;
 189     struct group *gr=getgrnam(group.c_str());
 190     if(!gr) {
 191       g_log<<Logger::Critical<<"Unable to look up gid of group '"<<group<<"': "<< (errno ? strerror(errno) : "not found") <<endl;
 192       exit(1);
 193     }
 194     newgid=gr->gr_gid;
 195   }
 196   return newgid;
 197 }
 198
 199
 200 // Retrieves an uid using a username.
 201 uid_t Utility::makeUidNumeric(const string &username)
 202 {
 203   uid_t newuid;
 204   if(!(newuid=atoi(username.c_str()))) {
 205     struct passwd *pw=getpwnam(username.c_str());
 206     if(!pw) {
 207       g_log<<Logger::Critical<<"Unable to look up uid of user '"<<username<<"': "<< (errno ? strerror(errno) : "not found") <<endl;
 208       exit(1);
 209     }
 210     newuid=pw->pw_uid;
 211   }
 212   return newuid;
 213 }
 214
 215 // Sets the random seed.
 216 void Utility::srandom(void)
 217 {
 218   struct timeval tv;
 219   gettimeofday(&tv, 0);
 220   ::srandom(tv.tv_sec ^ tv.tv_usec ^ getpid());
 221 }
 222
 223 // Writes a vector.
 224 int Utility::writev(int socket, const iovec *vector, size_t count )
 225 {
 226   return ::writev(socket,vector,count);
 227 }
 228
 229 /* this is cut and pasted from dietlibc, gratefully copied! */
 230 static int isleap(int year) {
 231   /* every fourth year is a leap year except for century years that are
 232    * not divisible by 400. */
 233   return (!(year%4) && ((year%100) || !(year%400)));
 234 }
 235
 236 time_t Utility::timegm(struct tm *const t)
 237 {
 238   const static short spm[13] = /* days per month -- nonleap! */
 239   { 0,
 240     (31),
 241     (31+28),
 242     (31+28+31),
 243     (31+28+31+30),
 244     (31+28+31+30+31),
 245     (31+28+31+30+31+30),
 246     (31+28+31+30+31+30+31),
 247     (31+28+31+30+31+30+31+31),
 248     (31+28+31+30+31+30+31+31+30),
 249     (31+28+31+30+31+30+31+31+30+31),
 250     (31+28+31+30+31+30+31+31+30+31+30),
 251     (31+28+31+30+31+30+31+31+30+31+30+31),
 252   };
 253
 254   time_t  day;
 255   time_t  i;
 256   time_t years = t->tm_year - 70;
 257
 258   if (t->tm_sec>60) { t->tm_min += t->tm_sec/60; t->tm_sec%=60; }
 259   if (t->tm_min>60) { t->tm_hour += t->tm_min/60; t->tm_min%=60; }
 260   if (t->tm_hour>60) { t->tm_mday += t->tm_hour/60; t->tm_hour%=60; }
 261   if (t->tm_mon>11) { t->tm_year += t->tm_mon/12; t->tm_mon%=12; }
 262
 263   while (t->tm_mday>spm[1+t->tm_mon]) {
 264     if (t->tm_mon==1 && isleap(t->tm_year+1900)) {
 265       if (t->tm_mon==31+29) break;
 266       --t->tm_mday;
 267     }
 268     t->tm_mday-=spm[t->tm_mon];
 269     ++t->tm_mon;
 270     if (t->tm_mon>11) { t->tm_mon=0; ++t->tm_year; }
 271   }
 272
 273   if (t->tm_year < 70)
 274     return (time_t) -1;
 275   /* Days since 1970 is 365 * number of years + number of leap years since 1970 */
 276   day  = years * 365 + (years + 1) / 4;
 277
 278   /* After 2100 we have to subtract 3 leap years for every 400 years
 279      This is not intuitive. Most mktime implementations do not support
 280      dates after 2059, anyway, so we might leave this out for its
 281      bloat. */
 282   if ((years -= 131) >= 0) {
 283     years /= 100;
 284     day -= (years >> 2) * 3 + 1;
 285     if ((years &= 3) == 3) years--;
 286     day -= years;
 287   }
 288
 289   day += t->tm_yday = spm [t->tm_mon] + t->tm_mday-1 + ( isleap (t->tm_year+1900)  &  (t->tm_mon > 1) );
 290
 291   /* day is now the number of days since 'Jan 1 1970' */
 292   i = 7;
 293   t->tm_wday = (day + 4) % i;                        /* Sunday=0, Monday=1, ..., Saturday=6 */
 294
 295   i = 24;
 296   day *= i;
 297   i = 60;
 298   return ((day + t->tm_hour) * i + t->tm_min) * i + t->tm_sec;
 299 }
 300