unix,win: add uv_random()

Add an API for obtaining cryptographically strong random data from the
system PRNG.

Co-authored-by: Saúl Ibarra Corretgé <s@saghul.net>
Refs: https://github.com/libuv/libuv/pull/1055
PR-URL: https://github.com/libuv/libuv/pull/2347
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>

1 files changed, 57 insertions, 0 deletions

diff --git a/src/unix/random-getentropy.c b/src/unix/random-getentropy.c
new file mode 100644
index 00000000..c45d9fd4
--- /dev/null
+++ b/src/unix/random-getentropy.c
@@ -0,0 +1,57 @@
+/* Copyright libuv contributors. All rights reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#include "uv.h"
+#include "internal.h"
+
+#include <stddef.h>
+#include <dlfcn.h>
+
+typedef int (*uv__getentropy_cb)(void *, size_t);
+
+static uv__getentropy_cb uv__getentropy;
+static uv_once_t once = UV_ONCE_INIT;
+
+
+static void uv__random_getentropy_init(void) {
+  uv__getentropy = (uv__getentropy_cb) dlsym(RTLD_DEFAULT, "getentropy");
+}
+
+
+int uv__random_getentropy(void* buf, size_t buflen) {
+  size_t pos;
+  size_t stride;
+
+  uv_once(&once, uv__random_getentropy_init);
+
+  if (uv__getentropy == NULL)
+    return UV_ENOSYS;
+
+  /* getentropy() returns an error for requests > 256 bytes. */
+  for (pos = 0, stride = 256; pos + stride < buflen; pos += stride)
+    if (uv__getentropy((char *) buf + pos, stride))
+      return UV__ERR(errno);
+
+  if (uv__getentropy((char *) buf + pos, buflen - pos))
+    return UV__ERR(errno);
+
+  return 0;
+}