1 files changed, 62 insertions, 44 deletions

diff --git a/random_seed.c b/random_seed.c
index 17727c6..f474e39 100644
--- a/random_seed.c
+++ b/random_seed.c
@@ -13,9 +13,23 @@
 #include "config.h"
 #include "strerror_override.h"
 #include <stdio.h>
+#include <stdlib.h>
+#ifdef HAVE_BSD_STDLIB_H
+#include <bsd/stdlib.h>
+#endif
 
 #define DEBUG_SEED(s)
 
+#if defined(__APPLE__) || defined(__unix__) || defined(__linux__)
+#define HAVE_DEV_RANDOM 1
+#endif
+
+#ifdef HAVE_ARC4RANDOM
+#undef HAVE_GETRANDOM
+#undef HAVE_DEV_RANDOM
+#undef HAVE_CRYPTGENRANDOM
+#endif
+
 #if defined ENABLE_RDRAND
 
 /* cpuid */
@@ -162,36 +176,38 @@ retry:
 #include <sys/random.h>
 #endif
 
-static int get_getrandom_seed(void)
+static int get_getrandom_seed(int *seed)
 {
-	DEBUG_SEED("get_dev_random_seed");
+	DEBUG_SEED("get_getrandom_seed");
 
-	int r;
 	ssize_t ret;
 
-	do {
-		ret = getrandom(&r, sizeof(r), 0);
+	do
+	{
+		ret = getrandom(seed, sizeof(*seed), GRND_NONBLOCK);
 	} while ((ret == -1) && (errno == EINTR));
 
 	if (ret == -1)
 	{
 		if (errno == ENOSYS) /* syscall not available in kernel */
 			return -1;
+		if (errno == EAGAIN) /* entropy not yet initialized */
+			return -1;
 
 		fprintf(stderr, "error from getrandom(): %s", strerror(errno));
-		exit(1);
+		return -1;
 	}
 
-	if (ret != sizeof(r))
+	if (ret != sizeof(*seed))
 		return -1;
 
-	return r;
+	return 0;
 }
 #endif /* defined HAVE_GETRANDOM */
 
-/* has_dev_urandom */
+/* get_dev_random_seed */
 
-#if defined(__APPLE__) || defined(__unix__) || defined(__linux__)
+#ifdef HAVE_DEV_RANDOM
 
 #include <fcntl.h>
 #include <string.h>
@@ -201,43 +217,34 @@ static int get_getrandom_seed(void)
 #include <stdlib.h>
 #include <sys/stat.h>
 
-#define HAVE_DEV_RANDOM 1
-
 static const char *dev_random_file = "/dev/urandom";
 
-static int has_dev_urandom(void)
+static int get_dev_random_seed(int *seed)
 {
+	DEBUG_SEED("get_dev_random_seed");
+
 	struct stat buf;
 	if (stat(dev_random_file, &buf))
-	{
-		return 0;
-	}
-	return ((buf.st_mode & S_IFCHR) != 0);
-}
-
-/* get_dev_random_seed */
-
-static int get_dev_random_seed(void)
-{
-	DEBUG_SEED("get_dev_random_seed");
+		return -1;
+	if ((buf.st_mode & S_IFCHR) == 0)
+		return -1;
 
 	int fd = open(dev_random_file, O_RDONLY);
 	if (fd < 0)
 	{
 		fprintf(stderr, "error opening %s: %s", dev_random_file, strerror(errno));
-		exit(1);
+		return -1;
 	}
 
-	int r;
-	ssize_t nread = read(fd, &r, sizeof(r));
-	if (nread != sizeof(r))
+	ssize_t nread = read(fd, seed, sizeof(*seed));
+	if (nread != sizeof(*seed))
 	{
 		fprintf(stderr, "error short read %s: %s", dev_random_file, strerror(errno));
-		exit(1);
+		return -1;
 	}
 
 	close(fd);
-	return r;
+	return 0;
 }
 
 #endif
@@ -260,13 +267,10 @@ static int get_dev_random_seed(void)
 #pragma comment(lib, "advapi32.lib")
 #endif
 
-static int get_time_seed(void);
-
-static int get_cryptgenrandom_seed(void)
+static int get_cryptgenrandom_seed(int *seed)
 {
 	HCRYPTPROV hProvider = 0;
 	DWORD dwFlags = CRYPT_VERIFYCONTEXT;
-	int r;
 
 	DEBUG_SEED("get_cryptgenrandom_seed");
 
@@ -277,34 +281,36 @@ static int get_cryptgenrandom_seed(void)
 	if (!CryptAcquireContextA(&hProvider, 0, 0, PROV_RSA_FULL, dwFlags))
 	{
 		fprintf(stderr, "error CryptAcquireContextA 0x%08lx", GetLastError());
-		r = get_time_seed();
+		return -1;
 	}
 	else
 	{
-		BOOL ret = CryptGenRandom(hProvider, sizeof(r), (BYTE*)&r);
+		BOOL ret = CryptGenRandom(hProvider, sizeof(*seed), (BYTE *)seed);
 		CryptReleaseContext(hProvider, 0);
 		if (!ret)
 		{
 			fprintf(stderr, "error CryptGenRandom 0x%08lx", GetLastError());
-			r = get_time_seed();
+			return -1;
 		}
 	}
 
-	return r;
+	return 0;
 }
 
 #endif
 
 /* get_time_seed */
 
+#ifndef HAVE_ARC4RANDOM
 #include <time.h>
 
 static int get_time_seed(void)
 {
 	DEBUG_SEED("get_time_seed");
 
-	return (int)time(NULL) * 433494437;
+	return (unsigned)time(NULL) * 433494437;
 }
+#endif
 
 /* json_c_get_random_seed */
 
@@ -317,19 +323,31 @@ int json_c_get_random_seed(void)
 	if (has_rdrand())
 		return get_rdrand_seed();
 #endif
+#ifdef HAVE_ARC4RANDOM
+	/* arc4random never fails, so use it if it's available */
+	return arc4random();
+#else
 #ifdef HAVE_GETRANDOM
 	{
-		int seed = get_getrandom_seed();
-		if (seed != -1)
+		int seed;
+		if (get_getrandom_seed(&seed) == 0)
 			return seed;
 	}
 #endif
 #if defined HAVE_DEV_RANDOM && HAVE_DEV_RANDOM
-	if (has_dev_urandom())
-		return get_dev_random_seed();
+	{
+		int seed;
+		if (get_dev_random_seed(&seed) == 0)
+			return seed;
+	}
 #endif
 #if defined HAVE_CRYPTGENRANDOM && HAVE_CRYPTGENRANDOM
-	return get_cryptgenrandom_seed();
+	{
+		int seed;
+		if (get_cryptgenrandom_seed(&seed) == 0)
+			return seed;
+	}
 #endif
 	return get_time_seed();
+#endif /* !HAVE_ARC4RANDOM */
 }