This change adds two new netlink routing attributes:
RTA_VIA and RTA_NEWDST.
RTA_VIA specifies the specifies the next machine to send a packet to
like RTA_GATEWAY. RTA_VIA differs from RTA_GATEWAY in that it
includes the address family of the address of the next machine to send
a packet to. Currently the MPLS code supports addresses in AF_INET,
AF_INET6 and AF_PACKET. For AF_INET and AF_INET6 the destination mac
address is acquired from the neighbour table. For AF_PACKET the
destination mac_address is specified in the netlink configuration.
I think raw destination mac address support with the family AF_PACKET
will prove useful. There is MPLS-TP which is defined to operate
on machines that do not support internet packets of any flavor. Further
seem to be corner cases where it can be useful. At this point
I don't care much either way.
RTA_NEWDST specifies the destination address to forward the packet
with. MPLS typically changes it's destination address at every hop.
For a swap operation RTA_NEWDST is specified with a length of one label.
For a push operation RTA_NEWDST is specified with two or more labels.
For a pop operation RTA_NEWDST is not specified or equivalently an emtpy
RTAN_NEWDST is specified.
Those new netlink attributes are used to implement handling of rt-netlink
RTM_NEWROUTE, RTM_DELROUTE, and RTM_GETROUTE messages, to maintain the
MPLS label table.
rtm_to_route_config parses a netlink RTM_NEWROUTE or RTM_DELROUTE message,
verify no unhandled attributes or unhandled values are present and sets
up the data structures for mpls_route_add and mpls_route_del.
I did my best to match up with the existing conventions with the caveats
that MPLS addresses are all destination-specific-addresses, and so
don't properly have a scope.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
03c0566542