Add a Rapid Commit option to Solicit messages and expect a Reply to
be received instead of an Advertise. When receiving a DHCPv6 message
from the server in state Solicit, continue testing whether the
message is a Reply. Ease up the message type checking, it's not fatal
if the message is of a wrong type.
Add helper functions to set/get the rapid commit of a lease. See
RFC 3315, sections 17., 17.1.2., 17.1.4. and 18.1.8.
Start sending Renew and Rebind DHCPv6 messages when respective timers T1
and T2 expire. Rebind messages do not include a Server ID option and the
Rebind procedure ends when the last IPv6 address valid lifetime expires,
whereafter the client restarts the address acquisition procedure by
Soliciting for available servers.
See RFC 3315, sections 18.1.3. and 18.1.4. for details.
Create a helper function to compute the remaining time in seconds from
time T2 to the IPv6 address with the longest lifetime. The computed
time is used as the Maximum Retransmission Duration in Rebinding state.
See RFC 3315, section 18.1.4. for details.
Provide a function to request more options from the DHCPv6 server.
Provide a sensible default set at startup and add test basic test
cases for the intended usage.
Define DNS and NTP related option codes and add comments for the
unassigned codes.
Enhance the test case by generating a Reply. With a properly formed
Reply the callback function will be called and the additional
earlier event loop exit can now be removed.
Enhance the test case by replying with an Advertise message to the
client. Copy the transaction id, IAID and DUID from the Solicit
message. Verify the Request message created by the DHCPv6 client
implementation and move the main loop exit to the end of the Request
message verification.
As described in RFC 3315, Section 17.1.2, a client has to wait until the
first timeout has elapsed before it is allowed to request IPv6 addresses
from the DHCPv6 server. This is indicated by a non-NULL lease and a
non-zero resend count. Should the Advertisement contain a preference
value of 255 or be received after the first timeout, IPv6 address
requesting is started immediately.
In response to these events, create a Request message and set up proper
resend timers to send the message to the server.
Update the start function so that the client state can be conveniently
changed with the previous message resend timers cleared. On initial
startup also create and bind to the UDP socket.
Add a basic test case excersising once more option parsing function
in addition to lease handling. Check that the address iteration
functions return the correct IPv6 address and lifetimes and that
only one address is returned. Also verify that the server ID and
preference values are read correctly.
When receiving DHCPv6 messages, discard the ones that are not meant
for DHCPv6 clients and verify the transaction id. Once that is done,
process the Advertise message and select the Advertise with the
highest preference.
Create a separate function for lease information parsing so that it
can be reused in other parts of the protocol. Verify both DUID and
IAID in the received message and store other necessary information
with the lease structure.
Add functionality to parse DHCPv6 Identity Association for
Non-temporary (IA_NA) and Temporary Addresses (IA_TA) options.
Both of them contain one or more IA Address (IAADDR) options
and optinally a status code option. Only the IA_NA option
contains lease lifetimes. See RFC 3315, sections 22.4., 22.5.,
22.6., 22.13. and appendix B. for details. If the lease
timeouts are not set, use the ones recommended for servers in
section 22.4.
Factor out common code in the form of an option header parsing
helper function.
Create a structure describing a DHCPv6 lease. Add internal functions
for creating a new lease and accessing the server ID, preference and
IAID. Provide functions for clearing addresses and associated timers.
External users are initially given only the capabilities of
referencing and unreferencing the lease structure.
Verify the Solicit message created by the DHCPv6 client code.
Provide local variants for detect_vm(), detect_container() and
detect_virtualization() defined in virt.h. This makes the DHCPv6
library believe it is run in a container and does not try to request
interface information from udev for the non-existing interface index
used by the test case code.
Implement the initial functionality used for creating a DHCPv6 Solicit
message containing the needed options and send it to the DHCPv6
broadcast address. Increase the sent message count and ensure that
the Solicit Initial Retransmission Time is strictly greater than
the Solicitation IRT as described in RFC 3315, section 17.1.2.
Add a function that creates a UDP socket bound to the given interface
and optionally to an IPv6 address. Add another function that will
send the DHCPv6 UDP packet to its destination.
Using IPV6_PKTINFO in setsockopt to bind the IPv6 socket to an
interface is documented in section 4. of RFC 3542, "Advanced Sockets
Application Program Interface (API) for IPv6"
Add a define for DHCPv6 Relay Agents and Servers multicast address as
its not available elsewhere.
Add option appending and parsing. DHCPv6 options are not aligned, thus
the option handling code must be able to handle options starting at
any byte boundary.
Add a test case for the basic option handling.
Add the core of DHCPv6 client message retransmission and upper bound
timer and message count handling according to RFC 3315 Secions 7.1.2
and 14. Omit the DHCPv6 initial delay; for now it is assumed that
systemd-networkd will provide decent startup randomization that will
desynchronize the clients.
When reinitializing the client, clear all timers.
Create structures describing Identity Association IDentifiers and
IPv6 lease addresses.
[tomegun: initialize the IAID when client is started. Base this off of the
predictable udev names, if available, as these satisfy the requirement of
the IAID, and base it off the mac addres otherwise, as that is the best we
have.]
Feed a Router Advertisement to the code and expect proper events
each time. The sending part is ignored, as all of it is static code
in the real dhcp_network_icmp6_send_rs() function.
Provide functions to bind the ICMPv6 socket to the approriate interface
and set multicast sending and receiving according to RFC 3493, section
5.2. and RFC 3542, sections 3. and 3.3. Filter out all ICMPv6 messages
except Router Advertisements for the socket in question according to
RFC 3542, section 3.2.
Send Router Solicitations to the all routers multicast group as
described in RFC 4861, section 6. and act on the received Router
Advertisments according to section 6.3.7.
Implement a similar API for ICMPv6 handling as is done for DHCPv4 and
DHCPv6.
Add an explicit stop state for IPv4LL so that the user can stop the
IPv4LL client from the callback. When returning from the callback,
check also the stop state in order to halt any further protocol
processing.
Similar to DHCP, the IPv4LL library user can decide to free the LL
client any time the callback is called. Guard against freeing the
LL client in the callback by introducing proper reference counting.
Also update code using the IPv4LL library to properly handle a
returned NULL from the notify and stop functions if the IPv4LL
client was freed.
Add an explicit stop state for the DHCP client so that the library
user can issue a stop at any time the callback has been called.
When returning from the callback, check also the stop state and
stop any further DHCP processing.
The DHCP library user can decide to free the DHCP client any time
the callback is called. After the callback has been called, other
computations may still be needed - the best example being a full
restart of the DHCP procedure in case of lease expiry.
Fix this by introducing proper reference counting. Properly handle
a returned NULL from the notify and stop functions if the DHCP
client was freed.
Even though client identifiers SHOULD be treated as opaque objects by
DHCP servers, follow the recommendation of a hardware type field with
value 0x01 (ethernet) followed by the hardware address as described in
RFC 2132.
Init-Reboot is tried if a client IP address has been given when
the DHCP client is started. In Init-Reboot, start by sending a
broadcast DHCP Request including the supplied client IP address
but without the server identifier. After sending the request,
enter Reboot state.
If a DHCP Ack is received, proceed to Bound state as usual. If a
DHCP Nak is received or the first timeout triggers, start the
address acquisition over from DHCP Init state.
See RFC 2131, sections 4.3.2, 4.4, 4.4.1 and 4.4.2 for details.
Upon startup the DHCP library will immediately send a DHCP Discover.
Handle the additional DHCP Discover checking and DHCP Offer sending
in test_addr_acq_recv_discover(). Write a zero UDP checksum, the
received XID and the faked MAC address into place to create a DHCP
message the library can accept.
Follow exactly the same steps when receiving a DHCP Request in
test_addr_acq_recv_request() and send the Ack. Check that the proper
addresses have been found by the DHCP library before exiting the
main loop and finishing the test.
Compute the 'secs' field as seconds since start of lease acquisition
procedure. Start off with a value of zero and increase it only for
each resent DHCP discover message. See the discussion before and
after http://www.ietf.org/mail-archive/web/dhcwg/current/msg05836.html
and Section 3.1 of RFC 2131.
Expiration of T1 timeout takes the client to the Rebinding state,
where it attempts to renew its lease. Start by opening a DCHP unicast
socket as there now is a proper IP address set.
Compute the resend timer as half of the remaining time down to a
minimum of 60 seconds (RFC2131). Modify DHCP Request sending to send
only UDP DHCP data when unicasting. Also modify DHCP Ack/Nak
receiving such that the client_receive_ack() takes care of using
either the full IP, UDP, DHCP packet or only the DHCP payload
depending whether the client is in Requesting or Renewing state.
Finally always report DHCP_EVENT_IP_ACQUIRE from Requesting state
and only DHCP_EVENT_IP_CHANGE if the IP address was modified when
the lease was renewed.
Create a helper functions setting up an unicast DHCP UDP socket and
sending data. Add function stubs for the test program.
[tomegun: initialize structs when allocating, and drop unneccesary 'err']
When a DHCP Nak is received, return a DHCP_EVENT_NO_LEASE event. If
some other DHCP message is received or an error happens when parsing
options, return -ENOMSG in order to ignore the packet. There may be
more than one server serving the same subnet, each server will send
its Offer to the client.
Ignore DHCP Ack packets if they are found to be erroneous or have
an unexpected xid by setting the result to zero instead of propagating
an error. Also remember to report a DHCP Nak and stop the DHCP client.
Process a DHCP Ack/Nak in much the same way as an DHCP Offer. Factor
out header verification and process options sent. Add notification
functionality with discrete values for the outcome of the DHCP Ack/
Nak processing.
Add maximum message size option to keep some DHCP server implementations
from sending too big messages. See ConnMan commit
0c5c862749c05193cf4c513628328c6db02b5222.
Create and send a DHCP Request message reusing already existing parts
of the code. This causes factoring out IP and UDP header creation and
moving next timeout calculation to be done every time in the timer
callback function independent of DHCP state. Also add an exponential
part to the timer calculation, bail out if there are errors while
resending the DHCP message for the sixth or more times.
Create a function for handling the full IP, UDP and DHCP packet
and tie it to the main loop. Verify IP and UDP headers and checksum.
Creat a new lease structure with using the values supplied in the
DHCP message. Free the lease structure when client is stopped.
Split out socket handling into a creation and a sending part. As a
result modify the test code.
Require a main loop to be set when creating a DHCP client. Set up
a timer to resend DHCP Discover messages and add a 0-2 second
delay to the timeout value. Move to state Selecting after successful
sending of a Discover message.
It was noticed by Grant Erickson in ConnMan commit
95e15c09350acf58d4707056ae2614570883ef66 that:
"Certain DHCP servers, such as that implemented in Mac OS X
(< 10.7) for its "Internet Sharing" feature, refuse to issue
a DHCP lease to clients that have not set a non-zero value
in their DISCOVER or REQUEST packets."
Set a fake MAC address and emulate raw packet sending. When the buffer
containing the Discover message is received, check selected IP and
UDP headers and compute IP header and UDP message checksums. Also
send the DHCP message for option parsing and expect a successful
outcome.
On starting the client, use the supplied interface mac address and create
a transaction id. Puzzle together an IP/UDP/DHCP Discover message, compute
checksums and send it out as a raw packet.
Create an additional function that constructs default options common to
all DHCP messages.
Set the DHCP Client ID option as noticed by Grant Erickson in ConnMan
commit b18d9798b3a0ae46ed87d6d2be8d5a474bf3ab1e:
"Some Internet gateways and Wi-Fi access points are unhappy when the
DHCPv4 client-id option (61) is missing and will refuse to issue a
DHCP lease."
Open a packet socket, create a link level header, send packet and
close socket. Adding it to a separate file makes testing of the
DHCP sending much easier, as the test program can supply any socket
to the DHCP client code.
Add checks for invalid lengths and parameters when using the option
appending function. Add also checks for adding options, see to it
that the resulting array is identical to the array of options added.
Add a structure describing the DHCP file, sname and trailing options
fields. Create a messge holding these fields and call the internal
option parsing function.
In the test callback function verify that only regular options are
passed and figure out which part of the DHCP message is the one that
is being processed. As the test program knows the full contents of
the test options in the test structure, skip all non-regular fields
and verify that the option provided to the callback indeed is the
one expected. Check also if non-regular option fields are to be
ignored in the end of the option field as the callback is not called
again and the final check when the whole message has been processed
needs to be successful.
Add a boolean flag for pretty-printing, anticipate there will be a
nice option to toggle it in the future.
Add functions to append and parse DHCP options. Not all options
are passed to the callback function, the ones not exposed are
pad, end, message type and overload. If indicated by the overload
option, file and sname fields will be examined for more options.
The option functions are internal to DHCP, add a new header files
for interal function prototypes.
Provide functionality for initializing a DHCP client struct, setting
interface index, last used address and additional options to request.
On initialization the most useful options are added by default.
Patrik Flykt