88 lines
2.7 KiB
C
88 lines
2.7 KiB
C
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#ifndef _MSC_VER
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# include <unistd.h>
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#endif
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#include "mirage_crypto.h"
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#include <caml/mlvalues.h>
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#include <caml/memory.h>
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#include <caml/unixsupport.h>
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#include <caml/bigarray.h>
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#if defined(__ANDROID_API__) && __ANDROID_API__ < 28
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// on Android 27 and earlier, we use Google's <sys/random.h> recommended arc4random_buf
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# include <stdlib.h>
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void raw_getrandom (uint8_t *data, size_t len) {
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arc4random_buf(data, len);
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}
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#elif defined(__linux) || defined(__GNU__)
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# include <errno.h>
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// on Linux and GNU/Hurd, we use getrandom and loop
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# if __GLIBC__ && __GLIBC__ <= 2 && __GLIBC_MINOR__ < 25
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# include <sys/syscall.h>
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# define getrandom(buf, len, flags) syscall(SYS_getrandom, (buf), (len), (flags))
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# else
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# include <sys/random.h>
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# define getrandom(buf, len, flags) getrandom((buf), (len), (flags))
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# endif
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void raw_getrandom (uint8_t *data, size_t len) {
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size_t off = 0;
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ssize_t r = 0;
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while (off < len) {
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r = getrandom(data + off, len - off, 0);
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if (r == -1) {
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if (errno == EINTR) continue;
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else uerror("getrandom", Nothing);
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}
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off += (size_t)r;
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}
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}
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#elif (defined(__FreeBSD__) || defined(__FreeBSD_kernel__) || defined(__DragonFly__) || defined(__OpenBSD__) || defined(__APPLE__)) || defined(__NetBSD__)
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// on BSD and macOS, loop (in pieces of 256) getentropy
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#if defined(__APPLE__)
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// on macOS, getentropy is defined in sys/random.h (on BSD in unistd.h)
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#include <sys/random.h>
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#endif
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#include <sys/param.h>
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void raw_getrandom (uint8_t *data, size_t len) {
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size_t rlen = 0;
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for (size_t i = 0; i <= len; i += 256) {
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rlen = MIN(256, len - i);
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if (getentropy(data + i, rlen) == -1) uerror("getentropy", Nothing);
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}
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}
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#elif (defined(_WIN32))
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/* There is a choice between using RtlGenRandom and BCryptGenRandom
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* here, and Microsoft does not make the choice obvious. It appears
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* that RtlGenRandom is best used when older Windows compatibility
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* is of concern, but requires some gymnastics around binding it
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* with the right calling convention.
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*
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* Therefore (https://github.com/mirage/mirage-crypto/pull/39) we
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* have decided to go with the more modern Windows API with bcrypt,
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* and make Windows 10 our minimum supported version of mirage-crypto.
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*/
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#include <windows.h>
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#include <ntstatus.h>
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#include <bcrypt.h>
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void raw_getrandom(uint8_t *data, size_t len) {
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NTSTATUS Status;
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Status = BCryptGenRandom(NULL, data, len, BCRYPT_USE_SYSTEM_PREFERRED_RNG);
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if (Status != STATUS_SUCCESS)
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uerror("BCryptGenRandom", Nothing);
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}
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#else
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#error "Retrieving random data not supported on this platform"
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#endif
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CAMLprim value mc_getrandom (value buf, value off, value len) {
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raw_getrandom(_bp_uint8_off(buf, off), Long_val(len));
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return Val_unit;
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}
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