svn commit: r227519 - head/lib/libc/gen

[David Schultz]

Author: das
Date: Tue Nov 15 05:45:46 2011
New Revision: 227519
URL: http://svn.freebsd.org/changeset/base/227519

Log:
  Sync the style, comments, and variable names of arc4random.c with
  OpenBSD's version (r1.22).  While some of our style changes were
  indeed small improvements, being able to easily track functionality
  changes in OpenBSD seems more useful.
  
  Also fix style bugs in the FreeBSD-specific parts of this file.
  
  No functional changes, as verified with md5.

Modified:
  head/lib/libc/gen/arc4random.c

Modified: head/lib/libc/gen/arc4random.c
==============================================================================
--- head/lib/libc/gen/arc4random.c	Tue Nov 15 01:48:53 2011	(r227518)
+++ head/lib/libc/gen/arc4random.c	Tue Nov 15 05:45:46 2011	(r227519)
@@ -1,3 +1,5 @@
+/*	$OpenBSD: arc4random.c,v 1.22 2010/12/22 08:23:42 otto Exp $	*/
+
 /*
  * Copyright (c) 1996, David Mazieres <dm at uun.org>
  * Copyright (c) 2008, Damien Miller <djm at openbsd.org>
@@ -24,11 +26,6 @@
  * which is a trade secret).  The same algorithm is used as a stream
  * cipher called "arcfour" in Tatu Ylonen's ssh package.
  *
- * Here the stream cipher has been modified always to include the time
- * when initializing the state.  That makes it impossible to
- * regenerate the same random sequence twice, so this can't be used
- * for encryption, but will generate good random numbers.
- *
  * RC4 is a registered trademark of RSA Laboratories.
  */
 
@@ -46,6 +43,12 @@ __FBSDID("$FreeBSD$");
 #include "libc_private.h"
 #include "un-namespace.h"
 
+#ifdef __GNUC__
+#define inline __inline
+#else				/* !__GNUC__ */
+#define inline
+#endif				/* !__GNUC__ */
+
 struct arc4_stream {
 	u_int8_t i;
 	u_int8_t j;
@@ -55,14 +58,14 @@ struct arc4_stream {
 static pthread_mutex_t	arc4random_mtx = PTHREAD_MUTEX_INITIALIZER;
 
 #define	RANDOMDEV	"/dev/random"
-#define KEYSIZE		128
-#define	THREAD_LOCK()						\
+#define	KEYSIZE		128
+#define	_ARC4_LOCK()						\
 	do {							\
 		if (__isthreaded)				\
 			_pthread_mutex_lock(&arc4random_mtx);	\
 	} while (0)
 
-#define	THREAD_UNLOCK()						\
+#define	_ARC4_UNLOCK()						\
 	do {							\
 		if (__isthreaded)				\
 			_pthread_mutex_unlock(&arc4random_mtx);	\
@@ -107,11 +110,11 @@ arc4_addrandom(u_char *dat, int datlen)
 static void
 arc4_stir(void)
 {
-	int done, fd, n;
+	int done, fd, i;
 	struct {
 		struct timeval	tv;
-		pid_t 		pid;
-		u_int8_t 	rnd[KEYSIZE];
+		pid_t		pid;
+		u_char	 	rnd[KEYSIZE];
 	} rdat;
 
 	fd = _open(RANDOMDEV, O_RDONLY, 0);
@@ -120,7 +123,7 @@ arc4_stir(void)
 		if (_read(fd, &rdat, KEYSIZE) == KEYSIZE)
 			done = 1;
 		(void)_close(fd);
-	} 
+	}
 	if (!done) {
 		(void)gettimeofday(&rdat.tv, NULL);
 		rdat.pid = getpid();
@@ -130,14 +133,11 @@ arc4_stir(void)
 	arc4_addrandom((u_char *)&rdat, KEYSIZE);
 
 	/*
-	 * Throw away the first N bytes of output, as suggested in the
-	 * paper "Weaknesses in the Key Scheduling Algorithm of RC4"
-	 * by Fluher, Mantin, and Shamir.  N=1024 is based on
-	 * suggestions in the paper "(Not So) Random Shuffles of RC4"
-	 * by Ilya Mironov.
+	 * Discard early keystream, as per recommendations in:
+	 * "(Not So) Random Shuffles of RC4" by Ilya Mironov.
 	 */
-	for (n = 0; n < 1024; n++)
-		(void) arc4_getbyte();
+	for (i = 0; i < 1024; i++)
+		(void)arc4_getbyte();
 	arc4_count = 1600000;
 }
 
@@ -152,7 +152,6 @@ arc4_getbyte(void)
 	sj = rs.s[rs.j];
 	rs.s[rs.i] = sj;
 	rs.s[rs.j] = si;
-
 	return (rs.s[(si + sj) & 0xff]);
 }
 
@@ -160,13 +159,11 @@ static inline u_int32_t
 arc4_getword(void)
 {
 	u_int32_t val;
-
 	val = arc4_getbyte() << 24;
 	val |= arc4_getbyte() << 16;
 	val |= arc4_getbyte() << 8;
 	val |= arc4_getbyte();
-
-	return (val);
+	return val;
 }
 
 static void
@@ -190,51 +187,48 @@ arc4_check_stir(void)
 void
 arc4random_stir(void)
 {
-	THREAD_LOCK();
+	_ARC4_LOCK();
 	arc4_check_init();
 	arc4_stir();
 	rs_stired = 1;
-	THREAD_UNLOCK();
+	_ARC4_UNLOCK();
 }
 
 void
 arc4random_addrandom(u_char *dat, int datlen)
 {
-	THREAD_LOCK();
+	_ARC4_LOCK();
 	arc4_check_init();
 	arc4_check_stir();
 	arc4_addrandom(dat, datlen);
-	THREAD_UNLOCK();
+	_ARC4_UNLOCK();
 }
 
 u_int32_t
 arc4random(void)
 {
-	u_int32_t rnd;
-
-	THREAD_LOCK();
+	u_int32_t val;
+	_ARC4_LOCK();
 	arc4_check_init();
 	arc4_check_stir();
-	rnd = arc4_getword();
+	val = arc4_getword();
 	arc4_count -= 4;
-	THREAD_UNLOCK();
-
-	return (rnd);
+	_ARC4_UNLOCK();
+	return val;
 }
 
 void
 arc4random_buf(void *_buf, size_t n)
 {
 	u_char *buf = (u_char *)_buf;
-
-	THREAD_LOCK();
+	_ARC4_LOCK();
 	arc4_check_init();
 	while (n--) {
 		arc4_check_stir();
 		buf[n] = arc4_getbyte();
 		arc4_count--;
 	}
-	THREAD_UNLOCK();
+	_ARC4_UNLOCK();
 }
 
 /*
@@ -253,7 +247,7 @@ arc4random_uniform(u_int32_t upper_bound
 	u_int32_t r, min;
 
 	if (upper_bound < 2)
-		return (0);
+		return 0;
 
 #if (ULONG_MAX > 0xffffffffUL)
 	min = 0x100000000UL % upper_bound;
@@ -279,7 +273,7 @@ arc4random_uniform(u_int32_t upper_bound
 			break;
 	}
 
-	return (r % upper_bound);
+	return r % upper_bound;
 }
 
 #if 0