Miscellaneous Notes
-------------------
-lib/uuid.c, used in OVSDB, assumes that it can obtain a high-quality
-random number seed at startup by reading from /dev/urandom. You may
-need to modify it if this is not true on your platform.
+lib/entropy.c assumes that it can obtain high-quality random number
+seeds at startup by reading from /dev/urandom. You will need to
+modify it if this is not true on your platform.
Questions
---------
lib/dpif.h \
lib/dynamic-string.c \
lib/dynamic-string.h \
+ lib/entropy.c \
+ lib/entropy.h \
lib/fatal-signal.c \
lib/fatal-signal.h \
lib/flow.c \
--- /dev/null
+/* Copyright (c) 2008, 2009, 2010 Nicira Networks
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <config.h>
+
+#include "entropy.h"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+#include "socket-util.h"
+#include "vlog.h"
+
+VLOG_DEFINE_THIS_MODULE(entropy)
+
+static const char urandom[] = "/dev/urandom";
+
+/* Initializes 'buffer' with 'n' bytes of high-quality random numbers. Returns
+ * 0 if successful, otherwise a positive errno value or EOF on error. */
+int
+get_entropy(void *buffer, size_t n)
+{
+ size_t bytes_read;
+ int error;
+ int fd;
+
+ fd = open(urandom, O_RDONLY);
+ if (fd < 0) {
+ VLOG_ERR("%s: open failed (%s)", urandom, strerror(errno));
+ return errno ? errno : EINVAL;
+ }
+
+ error = read_fully(fd, buffer, n, &bytes_read);
+ close(fd);
+
+ if (error) {
+ VLOG_ERR("%s: read error (%s)", urandom,
+ error == EOF ? "unexpected end of file" : strerror(error));
+ }
+ return error;
+}
+
+/* Initializes 'buffer' with 'n' bytes of high-quality random numbers. Exits
+ * if an error occurs. */
+void
+get_entropy_or_die(void *buffer, size_t n)
+{
+ int error = get_entropy(buffer, n);
+ if (error) {
+ ovs_fatal(error, "%s: read error", urandom);
+ }
+}
--- /dev/null
+/* Copyright (c) 2010 Nicira Networks
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ENTROPY_H
+#define ENTROPY_H 1
+
+#include <stddef.h>
+
+int get_entropy(void *, size_t);
+void get_entropy_or_die(void *, size_t);
+
+#endif /* entropy.h */
#include <fcntl.h>
#include <sys/time.h>
#include <sys/types.h>
-#include <unistd.h>
#include "aes128.h"
+#include "entropy.h"
#include "sha1.h"
-#include "socket-util.h"
#include "util.h"
static struct aes128 key;
return false;
}
\f
-static void
-read_urandom(void *buffer, size_t n)
-{
- static const char urandom[] = "/dev/urandom";
- size_t bytes_read;
- int error;
- int fd;
-
- fd = open(urandom, O_RDONLY);
- if (fd < 0) {
- ovs_fatal(errno, "%s: open failed", urandom);
- }
- error = read_fully(fd, buffer, n, &bytes_read);
- if (error == EOF) {
- ovs_fatal(0, "%s: unexpected end of file", urandom);
- } else if (error) {
- ovs_fatal(error, "%s: read error", urandom);
- }
- close(fd);
-}
-
static void
do_init(void)
{
gid_t gid;
/* Get seed data. */
- read_urandom(random_seed, sizeof random_seed);
+ get_entropy_or_die(random_seed, sizeof random_seed);
if (gettimeofday(&now, NULL)) {
ovs_fatal(errno, "gettimeofday failed");
}
aes128_schedule(&key, sha1);
/* Generate initial counter. */
- read_urandom(counter, sizeof counter);
+ get_entropy_or_die(counter, sizeof counter);
}
VLOG_MODULE(dpif_linux)
VLOG_MODULE(dpif_netdev)
VLOG_MODULE(dpctl)
+VLOG_MODULE(entropy)
VLOG_MODULE(ezio_term)
VLOG_MODULE(fail_open)
VLOG_MODULE(fatal_signal)