802.11 drivers will use ieee80211_find_rxnode to match each received
packet with the ieee80211_node belonging to the sender. The driver
will use the ieee80211_node to track the sender's RSSI and other
statistics for, e.g., rate adaptation.
ieee80211_find_rxnode "fakes-up" missing ieee80211_nodes in IBSS
mode and in ad-hoc demo mode when it is appropriate. See the comments
in the source.
Also add ieee80211_find_txnode, which looks up the ieee80211_node
belonging to a MAC destination. ieee80211_find_txnode will also
fake-up missing nodes in IBSS/ad-hoc demo mode.
In ieee80211_encap, use ieee80211_find_txnode. This fixes the bug
in ad hoc packet-transmission reported by Greg Troxel, Urban Boquist,
and Kurt Schreiner.