Commit c48ebde5 authored by Toke Høiland-Jørgensen's avatar Toke Høiland-Jørgensen Committed by Ondrej Zajicek (work)
Browse files

sysdep: Add wrapper to get random bytes 

Add a wrapper function in sysdep to get random bytes, and required checks
in configure.ac to select how to do it. The configure script tries, in
order, getrandom(), getentropy() and reading from /dev/urandom.
parent 91d04583

conf/conf.c

+1 −0
Original line number Diff line number Diff line
@@ -524,6 +524,7 @@ order_shutdown(int gr) 
  c->gr_down = gr;



  config_commit(c, RECONFIG_HARD, 0);

  random_close();

  shutting_down = 1;

}

configure.ac

+4 −0
Original line number Diff line number Diff line
@@ -374,6 +374,10 @@ elif test "$bird_cv_lib_log" != yes ; then 
  LIBS="$LIBS $bird_cv_lib_log"

fi



AC_CHECK_FUNCS(getrandom)

AC_CHECK_FUNCS(getentropy)

AC_CHECK_HEADERS(sys/random.h)



if test "$enable_debug" = yes ; then

  AC_DEFINE([DEBUGGING], [1], [Define to 1 if debugging is enabled])

  LDFLAGS="$LDFLAGS -rdynamic"

lib/birdlib.h

+3 −0
Original line number Diff line number Diff line
@@ -192,5 +192,8 @@ asm( 
/* Pseudorandom numbers */



u32 random_u32(void);

int random_bytes(char *buf, size_t size);

void random_close(void);

void random_init(void);



#endif

sysdep/unix/main.c

+1 −0
Original line number Diff line number Diff line
@@ -867,6 +867,7 @@ main(int argc, char **argv) 
  parse_args(argc, argv);

  log_switch(1, NULL, NULL);



  random_init();

  net_init();

  resource_init();

  timer_init();

sysdep/unix/random.c

+88 −0
Original line number Diff line number Diff line
@@ -7,6 +7,21 @@ 
 */



#include <stdlib.h>

#include <fcntl.h>

#include <unistd.h>

#include <errno.h>



#include "sysdep/config.h"



#ifdef HAVE_SYS_STAT_H

#  include <sys/stat.h>

#endif

#ifdef HAVE_LINUX_RANDOM_H

#  include <linux/random.h>

#endif

#if defined(HAVE_SYS_RANDOM_H) && (defined(HAVE_GETRANDOM) || defined(HAVE_GETENTROPY))

#    include <sys/random.h>

#endif



#include "nest/bird.h"
@@ -19,3 +34,76 @@ random_u32(void) 
  rand_high = random();

  return (rand_low & 0xffff) | ((rand_high & 0xffff) << 16);

}



void

random_init()

{

  char buf;

  /* get a single random byte to trip any errors early */

  random_bytes(&buf, sizeof(buf));

}



#if defined(HAVE_GETRANDOM) || defined(HAVE_GENTROPY)

int

random_bytes(char *buf, size_t size)

{

  int n;

  int flags = 0;

  while (0 < size) {

#if defined(HAVE_GETRANDOM)

    n = getrandom(buf, size, flags);

#else

    n = getentropy(buf, size);

#endif

    if (n < 0) {

      if (errno == EINTR)

        continue;

      die("Couldn't get random bytes: %m");

    }

    buf += n;

    size -= n;

  }



  return 0;

}



void random_close(void) {}



#else



static int urandom_fd = -1;

int random_bytes(char *buf, size_t size)

{

  int n;



  if (urandom_fd < 0)

  {

    urandom_fd = open("/dev/urandom", O_RDONLY);

    if (urandom_fd < 0)

      die("Couldn't open /dev/urandom: %m");

  }



  do

  {

    n = read(urandom_fd, buf, size);

    if (n <= 0) {

      if (errno == EINTR)

        continue;

      die("Couldn't read from /dev/urandom: %m");

    }

    buf += n;

    size -= n;

  } while (size > 0);



  return 0;

}



void

random_close(void)

{

  if (urandom_fd >= 0) {

    close(urandom_fd);

    urandom_fd = -1;

  }

}

#endif

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