This change allows the netstack to do NDP's Router Discovery as outlined by
RFC 4861 section 6.3.4.
Note, this change will not break existing uses of netstack as the default
configuration for the stack options is set in such a way that Router Discovery
will not be performed. See `stack.Options` and `stack.NDPConfigurations` for
more details.
This change introduces 2 options required to take advantage of Router Discovery,
all available under NDPConfigurations:
- HandleRAs: Whether or not NDP RAs are processes
- DiscoverDefaultRouters: Whether or not Router Discovery is performed
Another note: for a NIC to process Router Advertisements, it must not be a
router itself. Currently the netstack does not have per-interface routing
configuration; the routing/forwarding configuration is controlled stack-wide.
Therefore, if the stack is configured to enable forwarding/routing, no Router
Advertisements will be processed.
Tests: Unittest to make sure that Router Discovery and updates to the routing
table only occur if explicitly configured to do so. Unittest to make sure at
max stack.MaxDiscoveredDefaultRouters discovered default routers are remembered.
PiperOrigin-RevId: 278965143
This change validates incoming NDP Router Advertisements as per RFC 4861 section
6.1.2. It also includes the skeleton to handle Router Advertiements that arrive
on some NIC.
Tests: Unittest to make sure only valid NDP Router Advertisements are received/
not dropped.
PiperOrigin-RevId: 278891972
This change makes it so that NDP work is done using the per-interface NDP
configurations instead of the stack-wide default NDP configurations to correctly
implement RFC 4861 section 6.3.2 (note here, a host is a single NIC operating
as a host device), and RFC 4862 section 5.1.
Test: Test that we can set NDP configurations on a per-interface basis without
affecting the configurations of other interfaces or the stack-wide default. Also
make sure that after the configurations are updated, the updated configurations
are used for NDP processes (e.g. Duplicate Address Detection).
PiperOrigin-RevId: 276525661
This change introduces a new interface, stack.NDPDispatcher. It can be
implemented by the netstack integrator to receive NDP related events. As of this
change, only DAD related events are supported.
Tests: Existing tests were modified to use the NDPDispatcher's DAD events for
DAD tests where it needed to wait for DAD completing (failing and resolving).
PiperOrigin-RevId: 276338733
NDP Neighbor Solicitations sent during Duplicate Address Detection must have an
IP hop limit of 255, as all NDP Neighbor Solicitations should have.
Test: Test that DAD messages have the IPv6 hop limit field set to 255.
PiperOrigin-RevId: 275321680
This change adds support for Duplicate Address Detection on IPv6 addresses
as defined by RFC 4862 section 5.4.
Note, this change will not break existing uses of netstack as the default
configuration for the stack options is set in such a way that DAD will not be
performed. See `stack.Options` and `stack.NDPConfigurations` for more details.
Tests: Tests to make sure that the DAD process properly resolves or fails.
That is, tests make sure that DAD resolves only if:
- No other node is performing DAD for the same address
- No other node owns the same address
PiperOrigin-RevId: 275189471
Ghanan Gowripalan