wifi: mac80211: do not offer a mesh path if forwarding is disabled

wifi: mac80211: do not offer a mesh path if forwarding is disabled

When processing a PREQ the code would always check whether we have a
mesh path locally and reply accordingly. However, when forwarding is
disabled then we should not reply with this information as we will not
forward data packets down that path.

Move the check for dot11MeshForwarding up in the function and skip the
mesh path lookup in that case. In the else block, set forward to false
so that the rest of the function becomes a no-op and the
dot11MeshForwarding check does not need to be duplicated.

This explains an effect observed in the Freifunk community where mesh
forwarding is disabled. In that case a mesh with three STAs and only bad
links in between them, individual STAs would occionally have indirect
mpath entries. This should not have happened.

Signed-off-by: Benjamin Berg <benjamin@sipsolutions.net>
Reviewed-by: Rouven Czerwinski <rouven@czerwinskis.de>
Link: https://patch.msgid.link/20250430191042.3287004-1-benjamin@sipsolutions.net
Signed-off-by: Johannes Berg <johannes.berg@intel.com>