Atheros WLAN Driver Analysis: Assoc RSP Package Status Code = 5__wlan

The beginning of this problem is that some station cannot connect to an AP. Wireless grab bag after found station and AP between the first normal association interaction, that is station send probe REQ,AP reply probe RSP, and then station send AUTH packet ap reply AUTH packet, finally station send Assoc Req Package AP Reply Assoc RSP package. Here at first glance everything is normal, under normal circumstances station should send packets for normal data communication, but station again send probe req, and then the process was carried out again. In this way, the continuous repetition of the connection process, resulting in some station not normal connection, the following figure:

The analysis may be due to a problem with the Assoc RSP sent by the AP, causing station to feel that the connection is not working properly. Turn on the Assoc RSP sent by the AP details and found something unusual:

The status code here equals 5, which should normally be 0, indicating a successful connection;

Analysis of WLAN driver source in the IEEE80211_MGMT_AP.C function Ieee80211_setup_assocresp () found the status code group package location:

Just below the capinfo, the content of the status code comes from the fourth variable reason of Ieee80211_setup_assocresp (). Search for the location of the execution Ieee80211_setup_assocresp (). In the end we found a suspicious location in the Ieee80211_mlme_recv_assoc_request () function of ieee80211_mlme_ap.c, where the parameter reason was imported by assocstatus:

And the variable assocstatus may be set to the macro Ieee80211_reason_assoc_toomany, the value of this macro is 5

From a literal point of view should be due to the lack of AP resources, specific reasons to be investigated ...