From a61ebf552f71d8639b1a7584913c60fd49b8de90 Mon Sep 17 00:00:00 2001
From: Oscar Weiner-Wong <oscarweinerwong@yahoo.cn>
Date: Sun, 15 Jan 2012 21:12:36 +0100
Subject: [PATCH] Outsource creation of random MAC address to a new function
 create_random_mac.

---
 src/layer2.c |  2 +-
 src/mz.h     |  4 ++++
 src/tools.c  | 22 ++++++++++++++++++++++
 3 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/src/layer2.c b/src/layer2.c
index ebbc7d8..0c0f177 100644
--- a/src/layer2.c
+++ b/src/layer2.c
@@ -206,7 +206,7 @@ int send_arp ()
   
    if ( (getarg(tx.arg_string,"sendermac", argval)==1) || (getarg(tx.arg_string,"smac", argval)==1) )
      {
-	//TODO: Allow 'rand' as sendermac
+       //TODO: Allow 'rand' as sendermac
 	str2hex(argval,sendermac,6);
      }
    else
diff --git a/src/mz.h b/src/mz.h
index 083cffb..91b7ea0 100644
--- a/src/mz.h
+++ b/src/mz.h
@@ -552,6 +552,10 @@ int create_syslog_packet();
 //
 // ************************************
 
+// Sets eth_mac to a random unicast Ethernet MAC address.
+// Usage: create_random_mac(tx.eth_src);
+void create_random_mac(u_int8_t eth_mac[6]);
+
 // Converts MAC address specified in str into u_int8_t array
 // Usage: str2hex_mac ( "00:01:02:aa:ff:ee", src_addr )
 int str2hex_mac (char* str, u_int8_t *addr);
diff --git a/src/tools.c b/src/tools.c
index d95317c..c69a5fe 100644
--- a/src/tools.c
+++ b/src/tools.c
@@ -49,6 +49,7 @@
 //  mz_tok .............. Decomposes a string into tokens and maps them to args
 //                        Example usage: IPv6-addresses, user input for MPLS-tags
 //  delay_parse ......... Parses one or two strings for a delay specification and sets a struct timespec
+//  create_random_mac ... Creates a random unicast Ethernet MAC address
 //    
 ////////////////////////////////////////////////////////////////////////////////////////////
 
@@ -1340,3 +1341,24 @@ int delay_parse (struct timespec *t, char *a, char *b)
 	return 0;
 }
 
+// PURPOSE: Create random MAC address.
+// Create a random MAC address and store it in the array
+// passed in the function argument.
+//
+// NOTE: The MAC address returned is a unicast address.
+// 	Unicast addresses have the LSB always set to zero.
+//	At least that's what thay say on the Internet.. ;-)
+// 
+// RETURN VALUE: none 
+// ToDo: This function should have a return value.
+// 
+void create_random_mac(u_int8_t eth_mac[6]) 
+{
+	printf("I'm right here!\n");
+	int i;
+	for (i = 0; i < 6; i++)
+	{
+		tx.eth_src[i] = (u_int8_t) ( ((float) rand()/RAND_MAX)*256);
+	}
+	tx.eth_src[0] &= 0xFE; // keeps b-cast bit zero
+}
-- 
2.11.4.GIT