use faster arc4random() for small amounts fo data, some spaces; niels ok

1 files changed, 29 insertions, 34 deletions

diff --git a/sys/netinet/ip_id.c b/sys/netinet/ip_id.c
index 4f03a48d1a1..63fdf033485 100644
--- a/sys/netinet/ip_id.c
+++ b/sys/netinet/ip_id.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ip_id.c,v 1.2 1999/08/26 13:37:01 provos Exp $ */
+/* $OpenBSD: ip_id.c,v 1.3 2001/06/04 19:57:22 mickey Exp $ */
 
 /*
  * Copyright 1998 Niels Provos <provos@citi.umich.edu>
@@ -35,7 +35,7 @@
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-/* 
+/*
  * seed = random 15bit
  * n = prime, g0 = generator to n,
  * j = random so that gcd(j,n-1) == 1
@@ -43,7 +43,7 @@
  *
  * X[0] = random seed.
  * X[n] = a*X[n-1]+b mod m is a Linear Congruential Generator
- * with a = 7^(even random) mod m, 
+ * with a = 7^(even random) mod m,
  *      b = random with gcd(b,m) == 1
  *      m = 31104 and a maximal period of m-1.
  *
@@ -61,16 +61,16 @@
 
 #include <dev/rndvar.h>
 
-#define RU_OUT  180             /* Time after wich will be reseeded */
+#define RU_OUT  180		/* Time after wich will be reseeded */
 #define RU_MAX	30000		/* Uniq cycle, avoid blackjack prediction */
 #define RU_GEN	2		/* Starting generator */
 #define RU_N	32749		/* RU_N-1 = 2*2*3*2729 */
-#define RU_AGEN	7               /* determine ru_a as RU_AGEN^(2*rand) */
-#define RU_M	31104           /* RU_M = 2^7*3^5 - don't change */
+#define RU_AGEN	7		/* determine ru_a as RU_AGEN^(2*rand) */
+#define RU_M	31104		/* RU_M = 2^7*3^5 - don't change */
 
 #define PFAC_N 3
 const static u_int16_t pfacts[PFAC_N] = {
-	2, 
+	2,
 	3,
 	2729
 };
@@ -82,7 +82,7 @@ static u_int16_t ru_g;
 static u_int16_t ru_counter = 0;
 static u_int16_t ru_msb = 0;
 static long ru_reseed;
-static u_int32_t tmp;                /* Storage for unused random */
+static u_int32_t tmp;		/* Storage for unused random */
 
 static u_int16_t pmod __P((u_int16_t, u_int16_t, u_int16_t));
 static void ip_initid __P((void));
@@ -117,54 +117,49 @@ pmod(gen, exp, mod)
 	return (s);
 }
 
-/* 
- * Initalizes the seed and chooses a suitable generator. Also toggles 
+/*
+ * Initalizes the seed and chooses a suitable generator. Also toggles
  * the msb flag. The msb flag is used to generate two distinct
  * cycles of random numbers and thus avoiding reuse of ids.
  *
- * This function is called from id_randomid() when needed, an 
+ * This function is called from id_randomid() when needed, an
  * application does not have to worry about it.
  */
-static void 
+static void
 ip_initid(void)
 {
 	u_int16_t j, i;
 	int noprime = 1;
 
-	get_random_bytes((void *) &tmp, sizeof(tmp));
-	ru_x = (tmp & 0xFFFF) % RU_M;
+	ru_x = ((tmp = arc4random()) & 0xFFFF) % RU_M;
 
 	/* 15 bits of random seed */
 	ru_seed = (tmp >> 16) & 0x7FFF;
-	get_random_bytes((void *) &tmp, sizeof(tmp));
-	ru_seed2 = tmp & 0x7FFF;
-
-	get_random_bytes((void *) &tmp, sizeof(tmp));
+	ru_seed2 = arc4random() & 0x7FFF;
 
 	/* Determine the LCG we use */
-	ru_b = (tmp & 0xfffe) | 1;
+	ru_b = ((tmp = arc4random()) & 0xfffe) | 1;
 	ru_a = pmod(RU_AGEN, (tmp >> 16) & 0xfffe, RU_M);
 	while (ru_b % 3 == 0)
-	  ru_b += 2;
-	
-	get_random_bytes((void *) &tmp, sizeof(tmp));
-	j = tmp % RU_N;
+		ru_b += 2;
+
+	j = (tmp = arc4random()) % RU_N;
 	tmp = tmp >> 16;
 
-	/* 
+	/*
 	 * Do a fast gcd(j,RU_N-1), so we can find a j with
 	 * gcd(j, RU_N-1) == 1, giving a new generator for
 	 * RU_GEN^j mod RU_N
 	 */
 
 	while (noprime) {
-		for (i=0; i<PFAC_N; i++)
-			if (j%pfacts[i] == 0)
+		for (i = 0; i < PFAC_N; i++)
+			if (j % pfacts[i] == 0)
 				break;
 
-		if (i>=PFAC_N)
+		if (i >= PFAC_N)
 			noprime = 0;
-		else 
+		else
 			j = (j+1) % RU_N;
 	}
 
@@ -172,28 +167,28 @@ ip_initid(void)
 	ru_counter = 0;
 
 	ru_reseed = time.tv_sec + RU_OUT;
-	ru_msb = ru_msb == 0x8000 ? 0 : 0x8000; 
+	ru_msb = ru_msb == 0x8000 ? 0 : 0x8000;
 }
 
 u_int16_t
 ip_randomid(void)
 {
-        int i, n;
+	int i, n;
 
 	if (ru_counter >= RU_MAX || time.tv_sec > ru_reseed)
 		ip_initid();
 
 	if (!tmp)
-		get_random_bytes((void *) &tmp, sizeof(tmp));
+		tmp = arc4random();
 
 	/* Skip a random number of ids */
 	n = tmp & 0x3; tmp = tmp >> 2;
 	if (ru_counter + n >= RU_MAX)
-                ip_initid();
+		ip_initid();
 
 	for (i = 0; i <= n; i++)
-	        /* Linear Congruential Generator */
-	        ru_x = (ru_a*ru_x + ru_b) % RU_M;
+		/* Linear Congruential Generator */
+		ru_x = (ru_a * ru_x + ru_b) % RU_M;
 
 	ru_counter += i;