Roy Walker writes:

Here is a patch against the current subversion repository, that makes
udhcpc have an adjustable timeout.  Works for both foreground and before
it drops to the background.  This brings it more in-line with ISC dhcpc.

Use like so:
udhcpc --timeout=10 ...
or
udhcpc -T 10 ...

Still shooting for 1.1.1 this month?  Would really be great if you could
get this in that release.

Please give credit to Paul Pacheco - ppacheco@gmail.com.

networking/udhcp/dhcpc.h

@@ -30,6 +30,7 @@ struct client_config_t {
 	uint8_t *fqdn;			/* Optional fully qualified domain name to use */
 	int ifindex;			/* Index number of the interface to use */
 	int retries;			/* Max number of request packets */        
+	int timeout;			/* Number of seconds to try to get a lease */
 	uint8_t arp[6];			/* Our arp address */
 };