On 7/4/2023 4:34 PM, Marton Balint wrote:
On Tue, 4 Jul 2023, James Almer wrote:
Uses the existing code for av_get_random_seed() to return a buffer with
cryptographically secure random data, or an error if none could be
generated.
Signed-off-by: James Almer <jamr...@gmail.com>
---
TODO: APIChanges entry and minor version bump.
Also, if a new random.h header is prefered, i can move the prototype
there.
libavutil/random_seed.c | 46 ++++++++++++++++++++++++++---------------
libavutil/random_seed.h | 12 +++++++++++
2 files changed, 41 insertions(+), 17 deletions(-)
diff --git a/libavutil/random_seed.c b/libavutil/random_seed.c
index 66dd504ef0..39fb27c5ad 100644
--- a/libavutil/random_seed.c
+++ b/libavutil/random_seed.c
@@ -46,20 +46,20 @@
#define TEST 0
#endif
-static int read_random(uint32_t *dst, const char *file)
-{
#if HAVE_UNISTD_H
+static ssize_t read_random(uint8_t *dst, size_t len, const char *file)
+{
int fd = avpriv_open(file, O_RDONLY);
- int err = -1;
+ ssize_t err = -1;
+ if (len > SSIZE_MAX)
+ return -1;
if (fd == -1)
return -1;
- err = read(fd, dst, sizeof(*dst));
+ err = read(fd, dst, len);
close(fd);
return err;
-#else
- return -1;
#endif
}
@@ -118,29 +118,41 @@ static uint32_t get_generic_seed(void)
return AV_RB32(digest) + AV_RB32(digest + 16);
}
-uint32_t av_get_random_seed(void)
+int av_random(uint8_t* buf, size_t len)
{
- uint32_t seed;
-
#if HAVE_BCRYPT
BCRYPT_ALG_HANDLE algo_handle;
NTSTATUS ret = BCryptOpenAlgorithmProvider(&algo_handle,
BCRYPT_RNG_ALGORITHM,
MS_PRIMITIVE_PROVIDER, 0);
if (BCRYPT_SUCCESS(ret)) {
- NTSTATUS ret = BCryptGenRandom(algo_handle, (UCHAR*)&seed,
sizeof(seed), 0);
+ NTSTATUS ret = BCryptGenRandom(algo_handle, (PUCHAR)buf, len,
0);
BCryptCloseAlgorithmProvider(algo_handle, 0);
if (BCRYPT_SUCCESS(ret))
- return seed;
+ return 0;
}
#endif
#if HAVE_ARC4RANDOM
- return arc4random();
+ arc4random_buf(buf, len);
+ return 0;
+#endif
+
+#if HAVE_UNISTD_H
+ if (read_random(buf, len, "/dev/urandom") == len)
+ return 0;
+ if (read_random(buf, len, "/dev/random") == len)
+ return 0;
#endif
- if (read_random(&seed, "/dev/urandom") == sizeof(seed))
- return seed;
- if (read_random(&seed, "/dev/random") == sizeof(seed))
- return seed;
- return get_generic_seed();
+ return AVERROR_INVALIDDATA;
Probably AVERROR(ENOSYS) is a more suiting error code for this.
Not if any of the functions above were called but failed to fill the buffer.
I could add return AVERROR(ENOSYS) to the HAVE_UNISTD_H block, and
return AVERROR_INVALIDDATA outside.
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