add --random-mac option

dhtest.c

@@ -70,7 +70,8 @@ u_int32_t listen_timeout = 3600;
 void print_help(char *cmd)
 {
 	fprintf(stdout, "Usage: %s [ options ]\n", cmd);
-	fprintf(stdout, "  -m mac_address\n");
+	fprintf(stdout, "  -m MAC_address\n");
+	fprintf(stdout, "  -R, --random-mac\t\t\tUse a randomly generated MAC address\n");
 	fprintf(stdout, "  -r, --release\t\t\t\t# Releases obtained DHCP IP for corresponding MAC\n");
 	fprintf(stdout, "  -L, --option51-lease_time [ Lease_time ] # Option 51. Requested lease time in secondes\n");
 	fprintf(stdout, "  -I, --option50-ip\t[ IP_address ]\t# Option 50 IP address on DHCP discover\n");
@@ -107,9 +108,12 @@ int main(int argc, char *argv[])
 		exit(2);
 	}
 
+	init_rand();
+
 	int option_index = 0;
 	static struct option long_options[] = {
 		{ "mac", required_argument, 0, 'm' },
+		{ "random-mac", no_argument, 0, 'R' },
 		{ "interface", required_argument, 0, 'i' },
 		{ "vlan", required_argument, 0, 'v' },
 		{ "dhcp_xid", required_argument, 0, 'x' },
@@ -138,7 +142,7 @@ int main(int argc, char *argv[])
 
 	/*getopt routine to get command line arguments*/
 	while(get_tmp < argc) {
-		get_cmd  = getopt_long(argc, argv, "m:i:v:t:bfVrpansu::T:P:g:S:I:o:k:L:h:d:",\
+		get_cmd  = getopt_long(argc, argv, "m:Ri:v:t:bfVrpansu::T:P:g:S:I:o:k:L:h:d:",\
 				long_options, &option_index);
 		if(get_cmd == -1 ) {
 			break;
@@ -162,6 +166,21 @@ int main(int argc, char *argv[])
 				}
 				break;
 
+			case 'R':
+				{
+					int i;
+
+					for (i = 0; i < ETHER_ADDR_LEN; i++)
+						dhmac[i] = rand() & 0xff;
+
+					/* clear multicast bit, set the L bit, clear MSB */
+					dhmac[0] &= ~0x81;
+					dhmac[0] |= 0x02;
+
+					dhmac_flag = 1;
+				}
+				break;
+
 			case 'i':
 				iface_name = optarg;
 				break;

functions.c

@@ -313,15 +313,17 @@ int reset_dhopt_size()
 	return 0;
 }
 
+void init_rand() {
+	srand(time(NULL) ^ (getpid() << 16));
+}
+
 /*
  * Sets a random DHCP xid
  */
 int set_rand_dhcp_xid()
 {
-	if(dhcp_xid == 0) {
-		srand(time(NULL) ^ (getpid() << 16));
-		dhcp_xid = rand() % 0xffffffff;
-	}
+	if(dhcp_xid == 0)
+		dhcp_xid = (rand() % 0xfffffff0) + 1;
 	return 0;
 }
 

headers.h

@@ -20,6 +20,7 @@ int send_packet(int pkt_type);	/* Sends DHCP packet socket*/
 int recv_packet(int pkt_type);	/* Receives DHCP packet on socket*/
 
 int reset_dhopt_size();		/* Resets the dhopt_size to zero */
+void init_rand();
 int set_rand_dhcp_xid();	/* Sets a random DHCP xid */
 int build_option53(int msg_type);	/* Option53: MSGTYPE. Builds option53*/
 int build_option55();		/* Requested parameters list */