net: use common rand()/srand() functions

Replace rand() with the functions from lib/. The link-local network code
stores its own seed, derived from the MAC address. Thus making it
independent from calls to srand() in other modules.

Signed-off-by: Michael Walle <michael@walle.cc>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>

include/common.h

@@ -761,7 +761,9 @@ char *	strmhz(char *buf, unsigned long hz);
 #include <u-boot/crc.h>
 
 /* lib/rand.c */
-#ifdef CONFIG_RANDOM_MACADDR
+#if defined(CONFIG_RANDOM_MACADDR) || \
+	defined(CONFIG_BOOTP_RANDOM_DELAY) || \
+	defined(CONFIG_CMD_LINK_LOCAL)
 #define RAND_MAX -1U
 void srand(unsigned int seed);
 unsigned int rand(void);

lib/Makefile

@@ -67,8 +67,10 @@ COBJS-y += time.o
 COBJS-$(CONFIG_BOOTP_PXE) += uuid.o
 COBJS-y += vsprintf.o
 COBJS-$(CONFIG_RANDOM_MACADDR) += rand.o
+COBJS-$(CONFIG_BOOTP_RANDOM_DELAY) += rand.o
+COBJS-$(CONFIG_CMD_LINK_LOCAL) += rand.o
 
-COBJS	:= $(COBJS-y)
+COBJS	:= $(sort $(COBJS-y))
 SRCS	:= $(COBJS:.o=.c)
 OBJS	:= $(addprefix $(obj),$(COBJS))
 

net/Makefile

@@ -34,8 +34,6 @@ COBJS-$(CONFIG_CMD_DNS)  += dns.o
 COBJS-$(CONFIG_CMD_NET)  += eth.o
 COBJS-$(CONFIG_CMD_LINK_LOCAL) += link_local.o
 COBJS-$(CONFIG_CMD_NET)  += net.o
-COBJS-$(CONFIG_BOOTP_RANDOM_DELAY) += net_rand.o
-COBJS-$(CONFIG_CMD_LINK_LOCAL) += net_rand.o
 COBJS-$(CONFIG_CMD_NFS)  += nfs.o
 COBJS-$(CONFIG_CMD_PING) += ping.o
 COBJS-$(CONFIG_CMD_RARP) += rarp.o

net/link_local.c

@@ -56,6 +56,7 @@ static unsigned conflicts;
 static unsigned nprobes;
 static unsigned nclaims;
 static int ready;
+static unsigned int seed;
 
 static void link_local_timeout(void);
 
@@ -68,7 +69,7 @@ static IPaddr_t pick(void)
 	unsigned tmp;
 
 	do {
-		tmp = rand() & IN_CLASSB_HOST;
+		tmp = rand_r(&seed) & IN_CLASSB_HOST;
 	} while (tmp > (IN_CLASSB_HOST - 0x0200));
 	return (IPaddr_t) htonl((LINKLOCAL_ADDR + 0x0100) + tmp);
 }
@@ -78,7 +79,7 @@ static IPaddr_t pick(void)
  */
 static inline unsigned random_delay_ms(unsigned secs)
 {
-	return rand() % (secs * 1000);
+	return rand_r(&seed) % (secs * 1000);
 }
 
 static void configure_wait(void)
@@ -109,7 +110,7 @@ void link_local_start(void)
 	}
 	NetOurSubnetMask = IN_CLASSB_NET;
 
-	srand_mac();
+	seed = seed_mac();
 	if (ip == 0)
 		ip = pick();
 

net/net_rand.c

@@ -1,68 +0,0 @@
-/*
- *	Based on LiMon - BOOTP.
- *
- *	Copyright 1994, 1995, 2000 Neil Russell.
- *	(See License)
- *	Copyright 2000 Roland Borde
- *	Copyright 2000 Paolo Scaffardi
- *	Copyright 2000-2004 Wolfgang Denk, wd@denx.de
- */
-
-#include <common.h>
-#include <net.h>
-#include "net_rand.h"
-
-static ulong seed1, seed2;
-
-void srand_mac(void)
-{
-	ulong tst1, tst2, m_mask;
-	ulong m_value = 0;
-	int reg;
-	unsigned char bi_enetaddr[6];
-
-	/* get our mac */
-	eth_getenv_enetaddr("ethaddr", bi_enetaddr);
-
-	debug("BootpRequest => Our Mac: ");
-	for (reg = 0; reg < 6; reg++)
-		debug("%x%c", bi_enetaddr[reg], reg == 5 ? '\n' : ':');
-
-	/* Mac-Manipulation 2 get seed1 */
-	tst1 = 0;
-	tst2 = 0;
-	for (reg = 2; reg < 6; reg++) {
-		tst1 = tst1 << 8;
-		tst1 = tst1 | bi_enetaddr[reg];
-	}
-	for (reg = 0; reg < 2; reg++) {
-		tst2 = tst2 | bi_enetaddr[reg];
-		tst2 = tst2 << 8;
-	}
-
-	seed1 = tst1^tst2;
-
-	/* Mirror seed1*/
-	m_mask = 0x1;
-	for (reg = 1; reg <= 32; reg++) {
-		m_value |= (m_mask & seed1);
-		seed1 = seed1 >> 1;
-		m_value = m_value << 1;
-	}
-	seed1 = m_value;
-	seed2 = 0xb78d0945;
-}
-
-unsigned long rand(void)
-{
-	ulong sum;
-
-	/* Random Number Generator */
-	sum = seed1 + seed2;
-	if (sum < seed1 || sum < seed2)
-		sum++;
-	seed2 = seed1;
-	seed1 = sum;
-
-	return sum;
-}

net/net_rand.h

@@ -9,18 +9,35 @@
 #ifndef __NET_RAND_H__
 #define __NET_RAND_H__
 
-#define RAND_MAX 0xffffffff
+#include <common.h>
 
 /*
- * Seed the random number generator using the eth0 MAC address
+ * Return a seed for the PRNG derived from the eth0 MAC address.
  */
-void srand_mac(void);
+static inline unsigned int seed_mac(void)
+{
+	unsigned char enetaddr[6];
+	unsigned int seed;
+
+	/* get our mac */
+	eth_getenv_enetaddr("ethaddr", enetaddr);
+
+	seed = enetaddr[5];
+	seed ^= enetaddr[4] << 8;
+	seed ^= enetaddr[3] << 16;
+	seed ^= enetaddr[2] << 24;
+	seed ^= enetaddr[1];
+	seed ^= enetaddr[0] << 8;
+
+	return seed;
+}
 
 /*
- * Get a random number (after seeding with MAC address)
- *
- * @return random number
+ * Seed the random number generator using the eth0 MAC address.
  */
-unsigned long rand(void);
+static inline void srand_mac(void)
+{
+	srand(seed_mac());
+}
 
 #endif /* __NET_RAND_H__ */