random.c File Reference

Random number/string functions. More...

#include "config.h"
#include <errno.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include "random.h"
#include "exit.h"
#include "file.h"
#include "logging2.h"
#include "message.h"

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Functions
static int	mutt_randbuf (void *buf, size_t buflen)
	Fill a buffer with randomness.
void	mutt_rand_base32 (char *buf, size_t buflen)
	Fill a buffer with a base32-encoded random string.
uint64_t	mutt_rand64 (void)
	Create a 64-bit random number.

Variables
static FILE *	FpRandom = NULL
	FILE pointer of the random source.
static const unsigned char	Base32 [] = "abcdefghijklmnopqrstuvwxyz234567"
	Base 32 alphabet.

Detailed Description

Random number/string functions.

Authors

• Richard Russon

Copyright

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses/.

Definition in file random.c.

Function Documentation

mutt_randbuf()

static int mutt_randbuf ( void * buf, size_t buflen )

static

Fill a buffer with randomness.

Parameters

buf	Buffer for result
buflen	Size of buffer

Return values

0	Success
-1	Error

Definition at line 58 of file random.c.

{
  if (buflen > 1048576)
  {
    mutt_error(_("mutt_randbuf buflen=%zu"), buflen);
    return -1;
  }
 
#ifdef HAVE_GETRANDOM
  ssize_t rc;
  ssize_t count = 0;
  do
  {
    // getrandom() can return less than requested if there's insufficient
    // entropy or it's interrupted by a signal.
    rc = getrandom((char *) buf + count, buflen - count, 0);
    if (rc > 0)
      count += rc;
  } while (((rc >= 0) && (count < buflen)) || ((rc == -1) && (errno == EINTR)));
  if (count == buflen)
    return 0;
#endif
  /* let's try urandom in case we're on an old kernel, or the user has
   * configured selinux, seccomp or something to not allow getrandom */
  if (!FpRandom)
  {
    FpRandom = mutt_file_fopen("/dev/urandom", "r");
    if (!FpRandom)
    {
      mutt_error(_("open /dev/urandom: %s"), strerror(errno));
      return -1;
    }
    setbuf(FpRandom, NULL);
  }
  if (fread(buf, 1, buflen, FpRandom) != buflen)
  {
    mutt_error(_("read /dev/urandom: %s"), strerror(errno));
    return -1;
  }
 
  return 0;
}

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mutt_rand_base32()

void mutt_rand_base32	(	char *	buf,
		size_t	buflen )

Fill a buffer with a base32-encoded random string.

Parameters

buf	Buffer for result
buflen	Length of buffer

Definition at line 106 of file random.c.

{
  if (!buf || (buflen == 0))
    return;
 
  uint8_t *p = (uint8_t *) buf;
 
  if (mutt_randbuf(p, buflen) < 0)
    mutt_exit(1); // LCOV_EXCL_LINE
  for (size_t pos = 0; pos < buflen; pos++)
    p[pos] = Base32[p[pos] % 32];
}

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mutt_rand64()

uint64_t mutt_rand64

(

void

)

Create a 64-bit random number.

Return values

num	Random number

Definition at line 123 of file random.c.

{
  uint64_t num = 0;
 
  if (mutt_randbuf(&num, sizeof(num)) < 0)
    mutt_exit(1); // LCOV_EXCL_LINE
  return num;
}

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Variable Documentation

FpRandom

FILE* FpRandom = NULL

static

FILE pointer of the random source.

Definition at line 46 of file random.c.

Base32

const unsigned char Base32[] = "abcdefghijklmnopqrstuvwxyz234567"

static

Base 32 alphabet.

Definition at line 49 of file random.c.