void dhcprelease (packet)
	struct packet *packet;
{
	struct lease *lease;
	struct iaddr cip;
	int i;

	/* DHCPRELEASE must not specify address in requested-address
	   option, but old protocol specs weren't explicit about this,
	   so let it go. */
	if (packet -> options [DHO_DHCP_REQUESTED_ADDRESS].len) {
		note ("DHCPRELEASE from %s specified requested-address.",
		      print_hw_addr (packet -> raw -> htype,
				     packet -> raw -> hlen,
				     packet -> raw -> chaddr));
	}

	i = DHO_DHCP_CLIENT_IDENTIFIER;
	if (packet -> options [i].len) {
		lease = find_lease_by_uid (packet -> options [i].data,
					   packet -> options [i].len);

		/* See if we can find a lease that matches the IP address
		   the client is claiming. */
		for (; lease; lease = lease -> n_uid) {
			if (!memcmp (&packet -> raw -> ciaddr,
				     lease -> ip_addr.iabuf, 4)) {
				break;
			}
		}
	} else {
		/* The client is supposed to pass a valid client-identifier,
		   but the spec on this has changed historically, so try the
		   IP address in ciaddr if the client-identifier fails. */
		cip.len = 4;
		memcpy (cip.iabuf, &packet -> raw -> ciaddr, 4);
		lease = find_lease_by_ip_addr (cip);
	}

	note ("DHCPRELEASE of %s from %s via %s (%sfound)",
	      inet_ntoa (packet -> raw -> ciaddr),
	      print_hw_addr (packet -> raw -> htype,
			     packet -> raw -> hlen,
			     packet -> raw -> chaddr),
	      packet -> raw -> giaddr.s_addr
	      ? inet_ntoa (packet -> raw -> giaddr)
	      : packet -> interface -> name,
	      lease ? "" : "not ");

	/* If we found a lease, release it. */
	if (lease && lease -> ends > cur_time) {
		release_lease (lease);
	}
}