When a link is configured, wait until there is a Router Advertisement before
attempting to start DHCPv6. The intended DHCPv6 mode will be evaluated in
ndisc_router_handler() in networkd-ndisc.c.
Request prefix delegation for a new downstream link that is enabled
after any number of upstream DHCPv6 links. Submit the request after
the link has been configured with a link-local address.
If the upstream DHCPv6 client has already been configured to request
prefixes, attempt to re-assign any possible prefixes between the
already existing links and the new one. If no prefixes are yet
acquired, nothing will happen right away and any prefixes will be
distributed after a reply from the DHCPv6 server.
If none of the already existing downstream links have requested
DHCPv6 prefixes to be assigned, enable prefix delegation for each
client and restart them one by one if they are already running. This
causes the DHCPv6 clients to re-acquire addresses and prefixes and
to re-distribute them to all links when receiving an updated
response from their respective DHCPv6 servers. If the DHCPv6 client
in question was not already running, it is set to request prefixes
but not restarted.
When an error occurs while setting or restarting the DHCPv6 client,
log the incident and move over to the next link.
Fixes#9758.
Start with route set to NULL should there be no route created. Remove
the explicit route_free as the _cleanup_ will take care of that after
the continue;.
In order to shut down networkd properly, the delegated routes added
need to be removed properly, and as error reporting is wanted, the
network link is needed in the debug output.
Solve this by calling manager_dhcp6_prefix_remove_all(), which will
remove each prefix stored in the Manager structure, and while doing
that reference each link so that it isn't freed before the route
removal callback is called. This in turn causes the network link to
be referenced once more, and an explicit hashmap_remove() must be
called to remove the network link from the m->links hashmap.
Also, since the registered callback is not called when the DHCPv6
client is stopped with sd_dhcp6_client_stop(), an explicit call
to dhcp6_lease_pd_prefix_lost() needs to be made to clean up any
unreachable routes set up for the delegated prefixes.
Instead of setting many small unreachable routes for each of the /64
subnets that were not distributed between the links requesting delegated
prefixes, set one unreachable route for the size of the delegated
prefix. Each subnet asssigned to a downstream link will add a routable
subnet for that link, and as the subnet assigned to the downstream link
has a longer prefix than the whole delegated prefix, the downstream
link subnet routes are preferred over the unroutable delegated one.
The unreachable route is not added when the delegated prefix is exactly
a /64 as the prefix size cannot be used to sort out the order of routing
into a bigger blocking subnet with the smaller /64 punching routable
"holes" into it.
When stopping the DHCPv6 client, the unroutable delegated prefix is
removed before the downstream link prefixes are unassigned.
Since we now have the possibility to request prefixes to be delegated
without corresponding IPv6 addresses, it does not make sense to store
lease T1 and T2 timeouts in the otherwise unused IA_NA structure.
Therefore lease timeouts T1 and T2 are moved to the DHCPv6 client
structure, as there will be only one set of stateful timeouts required
by RFC 7550, Section 4.3.
Select T1 and T2 timeouts based on whether addresses or prefixes were
requested and what the server offered. The address and prefix timeouts
values have been computed earlier when the relevant DHCPv6 options were
parsed.
Add function to fetch the IAID for the delegated IA_PD prefix. In
order to keep things simple in the implemntation, the same IAID
is used with IA_NA addresses and IA_PD prefixes. But the DHCPv6
server can choose to return only IA_PD prefixes, and the client
can nowadays omit requesting of IA_NA addresses. Since the function
fetching said IAID from the lease looks only for IA_NA ones, it
will return an empty IAID, which of course does not match the one
set for prefixes.
Fix this by adding a function returning the IAID for the prefix.
RFC 7084, WPD-4, requires Customer Edge end routers to behave
according to the following:
"WPD-4: By default, the IPv6 CE router MUST initiate DHCPv6 prefix
delegation when either the M or O flags are set to 1 in a
received Router Advertisement (RA) message. Behavior of the
CE router to use DHCPv6 prefix delegation when the CE router
has not received any RA or received an RA with the M and the
O bits set to zero is out of scope for this document."
Since it cannot be automatically detected whether DHCPv6 is to be
operated as an CE end router or whether to initiate an Informational
exchange to obtain other useful network information via DHCPv6 when the
Router Advertisement 'O' bit is set, a 'ForceDHCPv6PDOtherInformation'
boolean network configuration option in the '[DHCP]' section of a is
introduced. Setting this option causes DHCPv6 to be started in stateful
mode, although only the 'O' bit is seen in the Router Advertisement.
When 'ForceDHCPv6PDOtherInformation' is set and the Router Advertisement
has only the Other information 'O' bit set, disable requests for IA_NA
addresses.
Fixes#9745.
Add function to enable/disable IA_NA address requests. Internally
handle the request as a bit mask and add IA_PD prefix delegation
to the same bit mask instead of having a separate boolean. Thus
the calling code can set requests for prefix and address delegation
separately. This is handy when supporting RFC 7084.
Add a check in the code that at least something is requested from
the server in Managed mode. By default request IA_NA addresses from
the DHCPv6 server. Although a value has been defined for IA_TA,
temporay IA_TA addresses are not yet requested.
Add helper function for fetching enabled/disabled state of Prefix
Delegation for a DHCPv6 client. Update function setting prefix
delegation to use an int instead of a boolean.
When computing the next network prefix to assign, compute the next
prefix to allocate based on the intended /64 assignment, not the
given prefix length for the whole prefix, e.g. /48, given to
systemd-networkd.
Fixes#9626.
The DHCPv6 client will set its state to DHCP6_STATE_STOPPED if
an error occurs or when receiving an Information Reply DHCPv6
message. Once in DHCP6_STATE_STOPPED, the DHCPv6 client needs
to be restarted by calling sd_dhcp6_client_start().
As of pull request #7796 client_reset() no longer closes the
network socket, thus a call to sd_dhcp6_client_start() needs to
check whether the file descriptor already exists in order not to
create a new one. Likewise, a call to sd_dhcp6_client_unref()
must now close the network socket as client_reset() is not
closing it.
Reported by asavah and Yu Watanabe.
The slightly modified review comments say that "...in theory
offsetof(DHCP6Option, data) is nicer than sizeof(DHCP6Option)
because the former removes alignment artifacts. In this
specific case there are no alignment whitespaces hence it's
fine, but out of a matter of principle offsetof() is preferred
over sizeof() in cases like this..."
Calling dhcp6_option_parse_address() will always return a value
< 0 on error even though lt_valid remains unset. This is more
than valgrind can safely detect, but let's fix the valgrind
nitpick anyway.
While fixing, use UINT32_MAX instead of ~0 on the same line.
When receiving one or more prefixes with variable length, assign a
64 bit long prefix for each link that has been configured for DHCPv6
prefix delegation and is not using DHCPv6 to fetch IPv6 adresses.
Keep assigning prefixes with length 64 from each prefix received via
DHCPv6 as long as there are prefixes left. If the number of prefixes
available from a prefix received via DHCPv6 is smaller than the
number of links, continue with the next delegated prefix, if any.
Remember the prefixes used for each link by storing them in a hash
and checking the hash each time a prefix is to be delegated. If an
error occurs when assigning a prefix to a link, try assigning the
prefix to another link. If the error occurs while updating the
prefix, log the situation and continue delegating the rest of the
prefixes.
Add a hashmap to the Manager struct that stores the association
between an IPv6 prefix and the network Link it is assigned to.
This is added in order to keep assigning the same prefixes with
the same links even though they are delegated at different times
or by different DHCPv6 clients.
As DHCPv6 leases may expire at some point, the delegated prefixes
have to be removed. Add a prefix removal function to the Router
Advertisement handling code.
Add a boolean that indicates whether the prefixes will always exist
or if they will time out after the assigned valid lifetime. In the
latter case calculate the expiry times for both preferred and valid
lifetimes for the prefixes, and decrease the remaining lifetimes
each time when a Router Advertisement is sent.
Should the prefix be updated, re-calculate the prefix lifetime. When
updating, update the existing entry, if any, with the lifetimes of
the added entry as the existing entry has its lifetimes set
according to its previously calculated expiry times.
Compute one set of minimum lifetimes for T1 and T2, i.e. the smaller
ones assigned to IA NA and IA PD. The lifetimes should be the same,
see RFC 7550 for details.
Request prefixes via DHCPv6 if there are networks that are
configured to distribute them. As specified in RFC 3633, a DHCPv6
client cannot redistribute the prefixes via Router Advertisements
on the same link. Ignore such networks, and print out a warning if
the link where DHCPv6 is enabled tries to do so.
Parse IA PD options and the prefixes in one or more PD Prefix
options. As the PD option contains identical data as the IA NA
option, re-use the same general data structures and sub-option
parsing logic. Similar to IA NA addresses, PD and associated
prefixes are stored in the address list of the IA PD lease.
An IA sub-option Status code will affect the IA NA and IA PD
option in question and cause those options to be ignored. A
Status code option in an IA Address or IA PD Prefix option
affects only that IA Address or Prefix.
Factor out IA Address option parsing and fix it so that all conditions
are checked before a new address is allocated and added to the address
list. Note also that the IA Address option can contain a nested Status
option. If the status in anything else than zero, the DHCPv6 server is
communicating an error condition and the address cannot be used.
Status option nesting is clarified in RFC 7550, Section 4.1.
The IA Address option is included as a typedef so that the lifetimes
can be inspected before allocating a new address and the option length
needed is easily available.
Sanitize code for parsing DHCPv6 IA NA and TA options and their
nested Status options so that the options can be fully and
properly ignored should they not be conformant to the specification.
Do this by defining a proper DHCP6Option structure and sending that
structure to the parsing function. The parsing function will then
not manipulate either any option data pointers or their lengths in
order to iterate over the current option. Needless to say, this
affects a few files including the test program.
The Network section IPv6PrefixDelegation= option takes two new
configuration values, namely "static" and "dhcpv6" in addition
to boolean yes and no values. Static prefixes in IPv6Prefix
sections are used when IPv6PrefixDelegation= option contains
"static", and DHCPv6 is queried for prefixes when the option
contains "dhcpv6". Both DHCPv6 and static prefixes are used when
the option contains a boolean true value. The default value is
false as before, meaning no prefixes are delegated.
Close DHCPv6 client socket file descriptor when
sd_dhcp6_client_stop() is called and not when client_reset() is
called. If left in client_reset(), any internal temporary stopping
of the DHCPv6 client with client_stop() will call client_reset()
after which the DHCPv6 client will not be able to receive any further
DHCPv6 messages.
Similarly, client_start() needs to enable events for the DHCPv6
socket file descriptor since a call to client_stop() will call
client_reset() which will remove it from the main loop. Events should
be turned off when no DHCPv6 messages are expected.
When another networking daemon or configuration is handling the
uplink connection, systemd-networkd won't have a network configuration
associated with the link, and therefore link->network will be NULL.
An assert will be triggered later on in the code when link->network is
NULL.
When EmitDNS or EmitDomains is set, automatically look up values
for Router Advertisement DNS and DNS search domain options starting
with the values in the IPv6PrefixDelegationsection, if any. If none
are found, use the values set for the network, and as a last resort
try with the preferred upstream network.
The default DNS lifetime and therefore Router Advertisement interval
is added to the public sd_radv.h header as the DNS lifetime depends
on the maximum advertisement interval.
Add EmitDNS= and EmitDomains= options to the IPv6PrefixDelegation
network configuration file section so that sending DNS servers
and DNS search domains can be configured independent of each other.
The default values for both are set to true.
Add Router Advertisement DNS Search List option as specified
in RFC 8106. The search list option uses and identical option
header as the RDNSS option and therefore the option header
structure can be reused.
If systemd is compiled with IDNA support, internationalization
of the provided search domain is applied, after which the search
list is written in wire format into the DNSSL option.
Parse DNS search domains from .network files so that they are included
in Router Advertisement DNSSL options.
DNS search domains are added to the [IPv6PrefixDelegation] section using
the following syntax:
Domains=foo.example.com bar.example.com
If IDNA libraries are enabled in systemd, international domain names
are supported.
Add prefix delegation documentation covering IPv6PrefixDelegation=
setting in the Network section as well as all the parameters and
the IPv6PrefixDelegation and IPv6Prefix sections implemented so
far, including DNS= and DNSLifetimeSec= settings.
Parse DNS IPv6 addresses and DNS server lifetime from .network files
so that they can be included in Router Advertisement RDNSS options.
RDNSS address and lifetime information is added to the
[IPv6PrefixDelegation] section according to the following syntax:
DNS=2001:db8::a:b 2001:db8::c:d
DNSLifetimeSec=1042
Test ICMPv6 Router Solicitation exponential backoff timer by
computing the minimum and maximum values according to RFC 7559,
Section 2 and the algorithm itself described in RFC 3315, Section
14. Reset the sd_ndisc timer to trigger after a zero second delay,
which causes the ndisc timeout to be triggered immediately once
the caller of the "sending" function returns to the main loop.
Move ICMPv6 Router Solicitation sending after timer computation so
that timers are already set up when the packet is being sent. This
makes it possible to create a test that inspects Router
Solicitation timer values when the Router Solicitation is sent out
on the network.
Instead of sending a fixed amount of Router Solicitiations, implement
the backoff algorithm proposed in RFC 7559. The backoff algorithm is
the same as used by DHCPv6.
Time out after 12s as specified in RFC 4861 in order not to delay
setting up a link for too long while sending Router Solicitations
in the background. Notice that after this change the callback will
receive a SD_NDISC_EVENT_TIMEOUT timeout event, and at a later point
when a router appears, a received Router Advertisment will cause the
callback to be called again with the SD_NDISC_EVENT_ROUTER event.
Add tests for prefix creation, router variable setting and finally
verify that a Router Advertisement is properly formatted when sending.
Also check that there is a Router Advertisment with zero lifetime
when Router Advertisement sending is stopped.
Receive Router Solicitations and send a unicast Router Advertisment
in response. Refactor ICMPv6 packet handling code so that the common
ICMPv6 validation parts are reused between the existing router
discovery and the new functionality adding reception of Router
Solicitation messages.
Create and remove the ICMPv6 Router Advertisement socket file
descriptor and implement Router Advertisment sending. As not
all options are mandatory, use IO vectors to point to the included
options and the prefix information.
Reuse and refactor the functionality already present for Router
Solicitations in order to create a socket for sending Router
Advertisements. Anticipate reception of incoming Router
Solicitations by setting the ICMPv6 filter accordingly. Also set
the unicast hop limit to 255 for ICMPv6 sockets as unicast Router
Advertisments are to be sent in response to Router Solicitations.
Update the Router Solicitation test case code with a function
definition in order to keep the test case working.
Router Advertisements are sent uniformly distributed between a
minimum and maximum time according to RFC 4861, Section 6.2.4.
Default values from RFC 4861 are for now used as minimum and
maximum Router Advertisement timeouts.
When stopping, a Router Advertisement with a router lifetime set
to zero is sent in order to inform any nodes that the interface
on this host no longer is a router.
Add variables for enabling Router Advertisements, router lifetime as
well as managed and other information flags indicating use of DHCPv6.
Add configuration of default router preferences as defined in RFC 4191.
IPv6PrefixDelegation in the [Network] section has to be set in order
to enable prefix delegation. The rest of the prefix delegation values
are stored in the [IPv6PrefixDelegation] section. The host will act as
a default router if it is given a non-zero lifetime with
RouterLifetimeSec. Managed and OtherInformation booleans set the level
of DHCPv6 support, and the RouterPreference configures the router's
preference between low, medium and high. Words 'normal' and 'default'
are added as synonyms for 'medium' just to make configuration simpler.
This adds a section like the following to .network configuration files:
[Network]
IPv6PrefixDelegation=true
[IPv6PrefixDelegation]
RouterLifetimeSec=2000
Managed=false
OtherInformation=true
RouterPreference=medium
Support zero or more [IPv6Prefix] sections in the network configuration
files. Each section can have one Prefix=<subnet>[/<prefixlength>]
option, with the preferred and valid lifetimes specified by
ValidLifetimeSec and PreferredLifetimeSec measured in seconds, and
with onlink and address autoconfiguration booleans specified by
OnLink and AddressAutoconfiguration variables.
This adds a section like the following to .network configuration files:
[IPv6Prefix]
Prefix=2001:db8:dead:beef::/64
OnLink=true
AddressAutoconfiguration=true
ValidLifetimeSec=1500
PreferredLifetimeSec=1000
Define Router Advertisement prefix structure. Add the Prefix
Information ICMPv6 option defined in RFC 4861 to the prefix
information structure, as it will simplify sending a Prefix
Information option later on. In order to handle endianness
correctly, the structure is redefined here instead of using
the one in netinet/icmp6.h.
Add functions to create and modify prefix information and set
default values as defined in RFC 4861, Section 6.2.1.
Reset also the counter for number of Router Solicitations sent when
the associated file descriptor is closed and the event source
unreferenced. With this change the router discovery can now be
stopped and restarted arbitrary many times.
When systemd-networkd is run on the same IPv6 enabled interface where
radvd is announcing prefixes, a route is being set up pointing to the
interface address. As this will fail with an invalid argument error,
the link is marked as failed and the following message like the
following will appear in in the logs:
systemd-networkd[21459]: eth1: Could not set NDisc route or address: Invalid argument
systemd-networkd[21459]: eth1: Failed
Should the interface be required by systemd-networkd-wait-online,
network-online.target will wait until its timeout hits thereby
significantly delaying system startup.
The fix is to check whether the gateway address obtained from NDisc
messages is equal to any of the interface addresses on the same link
and not set the NDisc route in that case.
RFC 2131 Section 4.1 says that
"If the ’giaddr’ field in a DHCP message from a client is non-zero,
the server sends any return messages to the ’DHCP server’ port on the
BOOTP relay agent whose address appears in ’giaddr’."
Fix this by adding a destination port when sending unicast UDP packets
and provide the server port when a BOOTP relay agent is being used.
The DHCP variable in the [Network] section of the network configuration
file moves the link to the configured state according to the following:
DHCP=yes Link is configured when either DHCPv4 or DHCPv6 succeed
DHCP=ipv4 Link is configured only when DHCPv4 succeeds
DHCP=ipv6 Link is configured only when DHCPv6 succeeds
DHCP=no Neither DHCPv4 or DHCPv6 is attempted
Reported by Martin Pitt.
Fixes https://github.com/systemd/systemd/issues/1368
Whenever a Router Advertisement is received, dhcp6_configure() will be
called. A Router Advertisment can also instruct DHCPv6 to start acquiring
IPv6 addresses in manged mode, if it previously was handling only other
information. As an Router Advertisment is also received after the DHCPv6
client has resumed from a suspend, fix the function not to assume DHCPv6
is currently running, but instead try to restart it. Handle
sd_dhcp6_start() returning -EALREADY indicating that the DHCPv6 client was
already running.
Collect all client unrefs in one place to unclutter the error handling.
Fixes https://github.com/systemd/systemd/issues/963
Update the test case to stop the ongoing Information Request exchange
before unsetting its state. To keep the test case callback verification
simpler, temporarily unset the callback function before stopping.
Prevent modifications to index, MAC address, DUID and Information
Request while the DHCPv6 client is running.
Require the DHCPv6 client to be stopped first instead of always
unconditionally restarting it if the caller calls
sd_dhcp6_client_start() more than once. With this change, handling
of for example incoming Router Advertisments becomes much easier.
Test option setting and getting in test_advertise_option(). Verify
that the information provided in DHCPv6 Reply messages is also
available in the Information and Solicit callbacks.
Although the SNTP option specified in RFC 4075 has been deprecated, some
servers are still sending NTP information with this option. Use the SNTP
information provided only if the NTP option is not present.
Update the test case as SNTP information is also requested.
Support DHCPv6 DNS search list option as specified in RFC 3646. This
option contains a list of DNS search domains encoded without compression
as specified in Section 8. of RFC 3315.
Patrik Flykt