#include <limits.h>
#include <tcl.h>
#include "randombytes.h"
static long getrandom_impl(void *buf, unsigned int buflen);
void randombytes(unsigned char *buffer, unsigned long long length) {
long gr_ret;
int errorCount = 0;
/*
* Ensure that the number of bytes requested can fit within
* the types we pass to other calls.
*
* The interface required by randombytes() used by TweetNaCl
* does not give us any way to handle errors. However,
* no buffer should exceed these amounts.
*/
if (length > UINT_MAX || length > LONG_MAX) {
Tcl_Panic("Buffer length is too large");
}
while (length > 0) {
gr_ret = getrandom_impl(buffer, length);
if (gr_ret < 0) {
errorCount++;
if (errorCount > 10) {
Tcl_Panic("Unable to generate random numbers");
}
continue;
}
errorCount = 0;
if (gr_ret == 0) {
continue;
}
buffer += gr_ret;
length -= gr_ret;
}
return;
}
#if defined(HAVE_GETRANDOM)
# ifdef HAVE_SYS_RANDOM_H
# include <sys/random.h>
# endif
static long getrandom_impl(void *buf, unsigned int buflen) {
ssize_t gr_ret;
gr_ret = getrandom(buf, buflen, 0);
return(gr_ret);
}
#elif defined(HAVE_GETENTROPY)
#include <unistd.h>
static long getrandom_impl(void *buf, unsigned int buflen) {
int ge_ret;
if (buflen > 255) {
buflen = 255;
}
ge_ret = getentropy(buf, buflen);
if (ge_ret != 0) {
return(-1);
}
return(buflen);
}
#elif defined(HAVE_CRYPTGENRANDOM)
# include <windows.h>
# include <wincrypt.h>
static long getrandom_impl(void *buf, unsigned int buflen) {
HCRYPTPROV provider;
BOOL cac_ret, cgr_ret;
cac_ret = CryptAcquireContextA(&provider, NULL, NULL, PROV_RSA_FULL, CRYPT_SILENT | CRYPT_VERIFYCONTEXT);
if (cac_ret == FALSE) {
cac_ret = CryptAcquireContextA(&provider, NULL, NULL, PROV_RSA_FULL, CRYPT_SILENT | CRYPT_VERIFYCONTEXT | CRYPT_NEWKEYSET);
}
if (cac_ret == FALSE) {
return(-1);
}
cgr_ret = CryptGenRandom(provider, buflen, (BYTE *) buf);
CryptReleaseContext(provider, 0);
if (cgr_ret == FALSE) {
return(-1);
}
return(buflen);
}
#else
# ifdef HAVE_SYS_TYPES_H
# include <sys/types.h>
# endif
# ifdef HAVE_SYS_STAT_H
# include <sys/stat.h>
# endif
# ifdef HAVE_FCNTL_H
# include <fcntl.h>
# endif
# ifdef HAVE_UNISTD_H
# include <unistd.h>
# endif
static long getrandom_impl(void *buf, unsigned int buflen) {
ssize_t read_ret;
long retval;
int fd = -1;
fd = open("/dev/urandom", O_RDONLY);
if (fd < 0) {
return(-1);
}
retval = 0;
while (buflen > 0) {
read_ret = read(fd, buf, buflen);
if (read_ret <= 0) {
continue;
}
buf += read_ret;
retval += read_ret;
buflen -= read_ret;
}
close(fd);
return(retval);
}
#endif