Make RNG work when we have arc4random() but not arc4random_buf()

thinkinnight · Feb 13, 2010 · 4ec8fea · 4ec8fea
1 parent d4de062
commit 4ec8fea
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Showing 3 changed files with 38 additions and 5 deletions.
diff --git a/arc4random.c b/arc4random.c
@@ -43,6 +43,10 @@
 #define ARC4RANDOM_EXPORT
 #endif
 
+#ifndef ARC4RANDOM_UINT32
+#define ARC4RANDOM_UINT32 uint32_t
+#endif
+
 #ifndef ARC4RANDOM_NO_INCLUDES
 #ifdef WIN32
 #include <wincrypt.h>
@@ -283,10 +287,10 @@ arc4random_addrandom(const unsigned char *dat, int datlen)
 #endif
 
 #ifndef ARC4RANDOM_NORANDOM
-ARC4RANDOM_EXPORT unsigned int
+ARC4RANDOM_EXPORT ARC4RANDOM_UINT32
 arc4random(void)
 {
-	unsigned int val;
+	ARC4RANDOM_UINT32 val;
 	_ARC4_LOCK();
 	arc4_count -= 4;
 	arc4_stir_if_needed();
@@ -324,7 +328,7 @@ arc4random_buf(void *_buf, size_t n)
 ARC4RANDOM_EXPORT unsigned int
 arc4random_uniform(unsigned int upper_bound)
 {
-	unsigned int r, min;
+	ARC4RANDOM_UINT32 r, min;
 
 	if (upper_bound < 2)
 		return 0;

diff --git a/configure.in b/configure.in
@@ -183,7 +183,7 @@ AC_C_INLINE
 AC_HEADER_TIME
 
 dnl Checks for library functions.
-AC_CHECK_FUNCS(gettimeofday vasprintf fcntl clock_gettime strtok_r strsep getaddrinfo getnameinfo strlcpy inet_ntop inet_pton signal sigaction strtoll inet_aton pipe eventfd sendfile mmap splice arc4random issetugid geteuid getegid getservbyname getprotobynumber setenv unsetenv putenv)
+AC_CHECK_FUNCS(gettimeofday vasprintf fcntl clock_gettime strtok_r strsep getaddrinfo getnameinfo strlcpy inet_ntop inet_pton signal sigaction strtoll inet_aton pipe eventfd sendfile mmap splice arc4random arc4random_buf issetugid geteuid getegid getservbyname getprotobynumber setenv unsetenv putenv)
 
 # Check for gethostbyname_r in all its glorious incompatible versions.
 #   (This is cut-and-pasted from Tor, which based its logic on

diff --git a/evutil_rand.c b/evutil_rand.c
@@ -39,11 +39,39 @@
 
 #ifdef _EVENT_HAVE_ARC4RANDOM
 #include <stdlib.h>
+#include <string.h>
 int
 evutil_secure_rng_init(void)
 {
 	return 0;
 }
+
+#ifndef _EVENT_HAVE_ARC4RANDOM_BUF
+static void
+arc4random_buf(void *buf, size_t n)
+{
+	unsigned char *b = buf;
+	/* Make sure that we start out with b at a 4-byte alignment; plenty
+	 * of CPUs care about this for 32-bit access. */
+	if (n >= 4 && ((ev_uintptr_t)b) & 3) {
+		ev_uint32_t u = arc4random();
+		int n_bytes = 4 - (((ev_uintptr_t)b) & 3);
+		memcpy(b, &u, n_bytes);
+		b += n_bytes;
+		n -= n_bytes;
+	}
+	while (n >= 4) {
+		*(ev_uint32_t*)b = arc4random();
+		b += 4;
+		n -= 4;
+	}
+	if (n) {
+		ev_uint32_t u = arc4random();
+		memcpy(b, &u, n);
+	}
+}
+#endif
+
 #else /* !_EVENT_HAVE_ARC4RANDOM { */
 
 #ifdef _EVENT_ssize_t
@@ -54,6 +82,7 @@ evutil_secure_rng_init(void)
 #define _ARC4_UNLOCK() EVLOCK_UNLOCK(arc4rand_lock, 0)
 static void *arc4rand_lock;
 
+#define ARC4RANDOM_UINT32 ev_uint32_t
 #define ARC4RANDOM_NOSTIR
 #define ARC4RANDOM_NORANDOM
 #define ARC4RANDOM_NOUNIFORM
@@ -87,6 +116,6 @@ evutil_secure_rng_get_bytes(void *buf, size_t n)
 void
 evutil_secure_rng_add_bytes(const char *buf, size_t n)
 {
-	arc4random_addrandom((const unsigned char*)buf, n);
+	arc4random_addrandom((unsigned char*)buf, n);
 }