gnrc_ipv6: Revert #5179

[miri64]

Reverts #5179.

Alternative to #5247.

Else-case that was discussed #5247 isn't necessary, since iface is already initialized with KERNEL_PID_UNDEF.

[OlegHahm]

Just a small question: would NDP work without a netif header for devices with multiple interfaces? IIRC it guesses the interface by matching the interface's addresses to the source address of the sender, right?

[miri64]

Usually NDP shouldn't go over loopback or similar interfaces, so I think it should work. The default behavior for an unknown interface should be to multicast the pacaket (the reply) then (all-routers for RS, all-nodes for all other).

[miri64]

I'm not sure where you have the "guessing" from. Can't find any of such things in the code.

[miri64]

The default behavior for an unknown interface should be to multicast the pacaket (the reply) then (all-routers for RS, all-nodes for all other).

If no reply for a packet is expected the packet should be ignored anyways, since it obviously did not came from a "real" interface.

[OlegHahm]

I'm not sure where you have the "guessing" from. Can't find any of such things in the code.

I was referring to:
https://github.com/RIOT-OS/RIOT/blob/master/sys/net/gnrc/network_layer/ipv6/gnrc_ipv6.c#L734

[miri64]

Ah, but that is not guessing, actually. If the address is assigned to the interface it is assigned to the interface and there is no ambiguity.

[OlegHahm]

But one can receive a packet that is targeted for an addressed assigned to interface A on interface B, right?

[miri64]

But one can receive a packet that is targeted for an addressed assigned to interface A on interface B, right?

Yes, but didn't we asses, that for "real" interfaces there is always a netif header, so iface isn't KERNEL_PID_UNDEF at this point?

[OlegHahm]

Hopefully.

[haukepetersen]

ACK

[haukepetersen]

Murdock is happy -> go.