autotest (dhcp): add test for NAK handling
This test sends NAK messages, without a server-ID, and
verifies that the DHCP client restarts DHCP negotiation.
We test two scenarios: a) the DHCP client is starting up
(but with a cached lease), and b) an already running DHCP
client is asked to renew its current lease.
BUG=chrome-os-partner:27930
TEST=manual
Manual test: ran this test before and after patching dhcpcd.
Test failed before the change, and passed afterwards. (It
took a couple iterations of this to get things right.)
Change-Id: I37329927e600568bc1268a1bfe54cfb17d9c5d5d
Reviewed-on: https://chromium-review.googlesource.com/194944
Reviewed-by: mukesh agrawal <[email protected]>
Tested-by: mukesh agrawal <[email protected]>
Commit-Queue: mukesh agrawal <[email protected]>
diff --git a/client/cros/dhcp_packet.py b/client/cros/dhcp_packet.py
index 61f7993..c117a26 100644
--- a/client/cros/dhcp_packet.py
+++ b/client/cros/dhcp_packet.py
@@ -596,6 +596,33 @@
MESSAGE_TYPE_ACK.option_value)
return packet
+ @staticmethod
+ def create_nak_packet(transaction_id, hwmac_addr):
+ """
+ Create a negative acknowledge packet.
+
+ @param transaction_id: The DHCP transaction ID.
+ @param hwmac_addr: The client's MAC address.
+ """
+ packet = DhcpPacket()
+ packet.set_field(FIELD_OP, FIELD_VALUE_OP_SERVER_RESPONSE)
+ packet.set_field(FIELD_HWTYPE, FIELD_VALUE_HWTYPE_10MB_ETH)
+ packet.set_field(FIELD_HWADDR_LEN, FIELD_VALUE_HWADDR_LEN_10MB_ETH)
+ # This has something to do with relay agents
+ packet.set_field(FIELD_RELAY_HOPS, 0)
+ packet.set_field(FIELD_TRANSACTION_ID, transaction_id)
+ packet.set_field(FIELD_TIME_SINCE_START, 0)
+ packet.set_field(FIELD_FLAGS, 0)
+ packet.set_field(FIELD_CLIENT_IP, IPV4_NULL_ADDRESS)
+ packet.set_field(FIELD_YOUR_IP, IPV4_NULL_ADDRESS)
+ packet.set_field(FIELD_SERVER_IP, IPV4_NULL_ADDRESS)
+ packet.set_field(FIELD_GATEWAY_IP, IPV4_NULL_ADDRESS)
+ packet.set_field(FIELD_CLIENT_HWADDR, hwmac_addr)
+ packet.set_field(FIELD_MAGIC_COOKIE, FIELD_VALUE_MAGIC_COOKIE)
+ packet.set_option(OPTION_DHCP_MESSAGE_TYPE,
+ MESSAGE_TYPE_NAK.option_value)
+ return packet
+
def __init__(self, byte_str=None):
"""
Create a DhcpPacket, filling in fields from a byte string if given.
