melifaro 493325342d Simplify the way of attaching IPv6 link-layer header. ... Problem description: How do we currently perform layer 2 resolution and header imposition: For IPv4 we have the following chain: ip_output() -> (ether|atm|whatever)_output() -> arpresolve() Lookup is done in proper place (link-layer output routine) and it is possible to provide cached lle data. For IPv6 situation is more complex: ip6_output() -> nd6_output() -> nd6_output_ifp() -> (whatever)_output() -> nd6_storelladdr() We have ip6_ouput() which calls nd6_output() instead of link output routine. nd6_output() does the following: * checks if lle exists, creates it if needed (similar to arpresolve()) * performes lle state transitions (similar to arpresolve()) * calls nd6_output_ifp() which pushes packets to link output routine along with running SeND/MAC hooks regardless of lle state (e.g. works as run-hooks placeholder). After that, iface output routine like ether_output() calls nd6_storelladdr() which performs lle lookup once again. As a result, we perform lookup twice for each outgoing packet for most types of interfaces. We also need to maintain runtime-checked table of 'nd6-free' interfaces (see nd6_need_cache()). Fix this behavior by eliminating first ND lookup. To be more specific: * make all nd6_output() consumers use nd6_output_ifp() instead * rename nd6_output[_slow]() to nd6_resolve_[slow]() * convert nd6_resolve() and nd6_resolve_slow() to arpresolve() semantics, e.g. copy L2 address to buffer instead of pushing packet towards lower layers * Make all nd6_storelladdr() users use nd6_resolve() * eliminate nd6_storelladdr() The resulting callchain is the following: ip6_output() -> nd6_output_ifp() -> (whatever)_output() -> nd6_resolve() Error handling: Currently sending packet to non-existing la results in ip6_<output|forward> -> nd6_output() -> nd6_output _lle() which returns 0. In new scenario packet is propagated to <ether|whatever>_output() -> nd6_resolve() which will return EWOULDBLOCK, and that result will be converted to 0. (And EWOULDBLOCK is actually used by IB/TOE code). Sponsored by: Yandex LLC Differential Revision: https://reviews.freebsd.org/D1469		2015-09-16 14:26:28 +00:00
..
ipfw	Fix packets/bytes accounting on i386.	2015-08-27 07:53:58 +00:00
pf	Simplify the way of attaching IPv6 link-layer header.	2015-09-16 14:26:28 +00:00