added nak script support

ChangeLog

@@ -1,4 +1,6 @@
 0.9.7 (pending)
++ Added script hook for DHCPNAK (nak), as well as providing the message option
+  (me)
 + Generate the paramaters request list by seeing what options in options.c are
   ored with OPTION_REQ in options.c
 + Fix dhcp renew forgetfullness on client (bug #1230)

README

@@ -96,6 +96,12 @@ are:
 	will not change, however, the other DHCP paramaters, such as the
 	default gateway, subnet mask, and dns server may change.
 
+	nak: This argument is used with udhcpc receives a NAK message.
+	The script with the deconfig argument will be called directly
+	afterwards, so no changes to the network interface are neccessary.
+	This hook is provided for purely informational purposes (the
+	message option may contain a reason for the NAK).
+
 The paramaters for enviromental variables are as follows:
 
 	$HOME		- The set $HOME env or "/"
@@ -128,6 +134,7 @@ The paramaters for enviromental variables are as follows:
 	lease		- The lease time, in seconds
 	dhcptype	- DHCP message type (safely ignored)
 	serverid	- The IP of the server
+	message		- Reason for a DHCPNAK
 	tftp		- The TFTP server name
 	bootfile	- The bootfile name
 

dhcpc.c

@@ -478,6 +478,7 @@ int main(int argc, char *argv[])
 				} else if (*message == DHCPNAK) {
 					/* return to init state */
 					LOG(LOG_INFO, "Received DHCP NAK");
+					run_script(&packet, "nak");
 					if (state != REQUESTING)
 						run_script(NULL, "deconfig");
 					state = INIT_SELECTING;