#if defined(__linux__)
#define _GNU_SOURCE
#endif
#include "randombytes.h"
#if defined(_WIN32)
#include <windows.h>
#include <wincrypt.h>
#endif
#if defined(__linux__)
#define RNDGETENTCNT 0x80045200
#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <poll.h>
#include <stdint.h>
#include <stdio.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <unistd.h>
#if !defined(SSIZE_MAX)
#define SSIZE_MAX (SIZE_MAX / 2 - 1)
#endif
#endif
#if defined(__unix__) || (defined(__APPLE__) && defined(__MACH__))
#include <sys/param.h>
#if defined(BSD)
#include <stdlib.h>
#endif
#endif
#if defined(__EMSCRIPTEN__)
#include <assert.h>
#include <emscripten.h>
#include <errno.h>
#include <stdbool.h>
#endif
#if defined(_WIN32)
static int randombytes_win32_randombytes(void *buf, const size_t n) {
HCRYPTPROV ctx;
BOOL tmp;
tmp = CryptAcquireContext(&ctx, NULL, NULL, PROV_RSA_FULL,
CRYPT_VERIFYCONTEXT);
if (tmp == FALSE) {
return -1;
}
tmp = CryptGenRandom(ctx, (DWORD)n, (BYTE *)buf);
if (tmp == FALSE) {
return -1;
}
tmp = CryptReleaseContext(ctx, 0);
if (tmp == FALSE) {
return -1;
}
return 0;
}
#endif
#if defined(__linux__) && defined(SYS_getrandom)
static int randombytes_linux_randombytes_getrandom(void *buf, size_t n) {
size_t offset = 0, chunk;
long int ret;
while (n > 0) {
chunk = n <= 33554431 ? n : 33554431;
do {
ret = syscall(SYS_getrandom, (char *)buf + offset, chunk, 0);
} while (ret == -1 && errno == EINTR);
if (ret < 0) {
return (int) ret;
}
offset += (size_t) ret;
n -= (size_t) ret;
}
assert(n == 0);
return 0;
}
#endif
#if defined(__linux__) && !defined(SYS_getrandom)
static int randombytes_linux_read_entropy_ioctl(int device, int *entropy) {
return ioctl(device, RNDGETENTCNT, entropy);
}
static int randombytes_linux_read_entropy_proc(FILE *stream, int *entropy) {
int retcode;
do {
rewind(stream);
retcode = fscanf(stream, "%d", entropy);
} while (retcode != 1 && errno == EINTR);
if (retcode != 1) {
return -1;
}
return 0;
}
static int randombytes_linux_wait_for_entropy(int device) {
enum { IOCTL,
PROC
} strategy = IOCTL;
const int bits = 128;
struct pollfd pfd;
int fd;
FILE *proc_file;
int retcode,
retcode_error = 0; int entropy = 0;
retcode = randombytes_linux_read_entropy_ioctl(device, &entropy);
if (retcode != 0 && errno == ENOTTY) {
strategy = PROC;
proc_file = fopen("/proc/sys/kernel/random/entropy_avail", "r");
} else if (retcode != 0) {
return -1;
}
if (entropy >= bits) {
return 0;
}
do {
fd = open("/dev/random", O_RDONLY);
} while (fd == -1 && errno == EINTR);
if (fd == -1) {
return -1;
}
pfd.fd = fd;
pfd.events = POLLIN;
for (;;) {
retcode = poll(&pfd, 1, -1);
if (retcode == -1 && (errno == EINTR || errno == EAGAIN)) {
continue;
} else if (retcode == 1) {
if (strategy == IOCTL) {
retcode =
randombytes_linux_read_entropy_ioctl(device, &entropy);
} else if (strategy == PROC) {
retcode =
randombytes_linux_read_entropy_proc(proc_file, &entropy);
} else {
return -1; }
if (retcode != 0) {
retcode_error = retcode;
break;
}
if (entropy >= bits) {
break;
}
} else {
retcode_error = -1;
break;
}
}
do {
retcode = close(fd);
} while (retcode == -1 && errno == EINTR);
if (strategy == PROC) {
do {
retcode = fclose(proc_file);
} while (retcode == -1 && errno == EINTR);
}
if (retcode_error != 0) {
return retcode_error;
}
return retcode;
}
static int randombytes_linux_randombytes_urandom(void *buf, size_t n) {
int fd;
size_t offset = 0, count;
ssize_t tmp;
do {
fd = open("/dev/urandom", O_RDONLY);
} while (fd == -1 && errno == EINTR);
if (fd == -1) {
return -1;
}
if (randombytes_linux_wait_for_entropy(fd) == -1) {
return -1;
}
while (n > 0) {
count = n <= SSIZE_MAX ? n : SSIZE_MAX;
tmp = read(fd, (char *)buf + offset, count);
if (tmp == -1 && (errno == EAGAIN || errno == EINTR)) {
continue;
}
if (tmp == -1) {
return -1;
}
offset += tmp;
n -= tmp;
}
assert(n == 0);
return 0;
}
#endif
#if defined(BSD)
static int randombytes_bsd_randombytes(void *buf, size_t n) {
arc4random_buf(buf, n);
return 0;
}
#endif
#if defined(__EMSCRIPTEN__)
static int randombytes_js_randombytes_nodejs(void *buf, size_t n) {
const int ret = EM_ASM_INT({
var crypto;
try {
crypto = require('crypto');
} catch (error) {
return -2;
}
try {
writeArrayToMemory(crypto.randomBytes($1), $0);
return 0;
} catch (error) {
return -1;
}
},
buf, n);
switch (ret) {
case 0:
return 0;
case -1:
errno = EINVAL;
return -1;
case -2:
errno = ENOSYS;
return -1;
}
assert(false); }
#endif
int randombytes(uint8_t *buf, size_t n) {
#if defined(__EMSCRIPTEN__)
return randombytes_js_randombytes_nodejs(buf, n);
#elif defined(__linux__)
#if defined(SYS_getrandom)
return randombytes_linux_randombytes_getrandom(buf, n);
#else
return randombytes_linux_randombytes_urandom(buf, n);
#endif
#elif defined(BSD)
return randombytes_bsd_randombytes(buf, n);
#elif defined(_WIN32)
return randombytes_win32_randombytes(buf, n);
#else
#error "randombytes(...) is not supported on this platform"
#endif
}