--- /dev/null
+/* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */
+/* lib/crypto/krb/prng/fortuna/prng_os.c - OS-native PRNG implementation */
+/*
+ * Copyright (C) 2011 by the Massachusetts Institute of Technology.
+ * All rights reserved.
+ *
+ *
+ * Export of this software from the United States of America may require
+ * a specific license from the United States Government. It is the
+ * responsibility of any person or organization contemplating export to
+ * obtain such a license before exporting.
+ *
+ * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
+ * distribute this software and its documentation for any purpose and
+ * without fee is hereby granted, provided that the above copyright
+ * notice appear in all copies and that both that copyright notice and
+ * this permission notice appear in supporting documentation, and that
+ * the name of M.I.T. not be used in advertising or publicity pertaining
+ * to distribution of the software without specific, written prior
+ * permission. Furthermore if you modify this software you must label
+ * your software as modified software and not distribute it in such a
+ * fashion that it might be confused with the original M.I.T. software.
+ * M.I.T. makes no representations about the suitability of
+ * this software for any purpose. It is provided "as is" without express
+ * or implied warranty.
+ */
+
+/*
+ * This file implements a PRNG module which relies on the system's /dev/urandom
+ * device. An OS packager can select this module given sufficient confidence
+ * in the operating system's native PRNG quality.
+ */
+
+#include "k5-int.h"
+#include "prng.h"
+
+#define DEVICE "/dev/urandom"
+
+static int fd = -1;
+
+int
+k5_prng_init(void)
+{
+ /* Try to open the random device read-write; if that fails, read-only is
+ * okay. */
+ fd = open(DEVICE, O_RDWR, 0);
+ if (fd == -1)
+ fd = open(DEVICE, O_RDONLY, 0);
+ if (fd == -1)
+ return errno;
+ return 0;
+}
+
+void
+k5_prng_cleanup(void)
+{
+ close(fd);
+ fd = -1;
+}
+
+krb5_error_code KRB5_CALLCONV
+krb5_c_random_add_entropy(krb5_context context, unsigned int randsource,
+ const krb5_data *indata)
+{
+ krb5_error_code ret;
+
+ ret = krb5int_crypto_init();
+ if (ret)
+ return ret;
+
+ /* Some random devices let user-space processes contribute entropy. Don't
+ * worry if this fails. */
+ (void)write(fd, indata->data, indata->length);
+ return 0;
+}
+
+krb5_error_code KRB5_CALLCONV
+krb5_c_random_make_octets(krb5_context context, krb5_data *outdata)
+{
+ char *buf = outdata->data;
+ size_t len = outdata->length;
+ ssize_t count;
+
+ while (len > 0) {
+ count = read(fd, buf, len);
+ if (count == 0) /* Not expected from a random device. */
+ return KRB5_CRYPTO_INTERNAL;
+ if (count == -1)
+ return errno;
+ buf += count;
+ len -= count;
+ }
+ return 0;
+}