Factor out getrnd() and rename to getentropy().

Factor out the arc4random seeding into its own file and change the
interface to match getentropy.  Use native getentropy if available.
This will make it easier to resync OpenBSD changes to arc4random.
Prompted by bz#3467, ok djm@.

1 files changed, 82 insertions, 0 deletions

diff --git a/openbsd-compat/bsd-getentropy.c b/openbsd-compat/bsd-getentropy.c
new file mode 100644
index 000000000..1733e2873
--- /dev/null
+++ b/openbsd-compat/bsd-getentropy.c
@@ -0,0 +1,82 @@
+/*
+ * Copyright (c) 1996, David Mazieres <dm@uun.org>
+ * Copyright (c) 2008, Damien Miller <djm@openbsd.org>
+ * Copyright (c) 2013, Markus Friedl <markus@openbsd.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include "includes.h"
+
+#ifndef HAVE_GETENTROPY
+
+#ifndef SSH_RANDOM_DEV
+# define SSH_RANDOM_DEV "/dev/urandom"
+#endif /* SSH_RANDOM_DEV */
+
+#include <sys/types.h>
+#ifdef HAVE_SYS_RANDOM_H
+# include <sys/random.h>
+#endif
+
+#include <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#ifdef WITH_OPENSSL
+#include <openssl/rand.h>
+#include <openssl/err.h>
+#endif
+
+#include "log.h"
+
+int
+getentropy(void *s, size_t len)
+{
+#ifdef WITH_OPENSSL
+	if (RAND_bytes(s, len) <= 0)
+		fatal("Couldn't obtain random bytes (error 0x%lx)",
+		    (unsigned long)ERR_get_error());
+#else
+	int fd, save_errno;
+	ssize_t r;
+	size_t o = 0;
+
+#ifdef HAVE_GETRANDOM
+	if ((r = getrandom(s, len, 0)) > 0 && (size_t)r == len)
+		return 0;
+#endif /* HAVE_GETRANDOM */
+
+	if ((fd = open(SSH_RANDOM_DEV, O_RDONLY)) == -1) {
+		save_errno = errno;
+		/* Try egd/prngd before giving up. */
+		if (seed_from_prngd(s, len) == 0)
+			return 0;
+		fatal("Couldn't open %s: %s", SSH_RANDOM_DEV,
+		    strerror(save_errno));
+	}
+	while (o < len) {
+		r = read(fd, (u_char *)s + o, len - o);
+		if (r < 0) {
+			if (errno == EAGAIN || errno == EINTR ||
+			    errno == EWOULDBLOCK)
+				continue;
+			fatal("read %s: %s", SSH_RANDOM_DEV, strerror(errno));
+		}
+		o += r;
+	}
+	close(fd);
+#endif /* WITH_OPENSSL */
+	return 0;
+}
+#endif /* WITH_GETENTROPY */