Upon receiving FST Setup Request from some peer on some interface,
search is made to see if same peer is connected on other interface with
specific band_id. With multiple peers, bug in
fst_group_does_iface_appear_in_other_mbies() caused wrong peer address
to be returned sometimes.
Fix this with a modified, simplified search algorithm of peer's "other"
connection.
Signed-off-by: Dedy Lansky <qca_dlansky@qca.qualcomm.com>
Upon receiving FST setup request on old band, the peer is searched on
new band. The assumption is that MB IE from this peer on new band
previously received either in assoc event or in FST setup request.
There are cases in which above assumption doesn't work, peer is not
found and session setup fails. For example:
- STA connects over 11ac. Due to driver limitation, MB IE is not included
in assoc event
- STA connects over 11ad. MB IE included in assoc event.
- FST session established on 11ac band, with AP as initiator. i.e. FST
setup request sent in AP=>STA direction. STA searches for peer's (AP)
MB IE on 11ad band which exists.
- FST switch occur
- FST session established on 11ad band, with STA as initiator. i.e. FST
setup request sent in STA=>AP direction. AP searches for peer's (STA)
MB IE on 11ac band which are absent.
For fixing the above, consider also peers without MB IE as candidates in
the search algorithm.
Signed-off-by: Dedy Lansky <qca_dlansky@qca.qualcomm.com>
Modify the FST peer connection check so it won't skip peers without MB
IEs making it more permissive for peers that didn't provide MB IEs
during association request. This can be helpful, e.g., in cases where a
STA's interface connected before it was added to the FST group. This
allows the AP to receive FST Action frames and initiate session with a
STA via STA's interface that doesn't expose MB IEs.
The adjusted FST protocol is still safe, as it protects itself in many
other ways (checking band info and it's accordance to the interfaces,
Setup IDs, connection states of the interfaces involved, etc.)
effectively avoiding all types of invalid situations.
Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>
FST STA should always expose its MB IEs regardless of its connection
state and whether the connected AP is currently FST-enabled or not.
Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>
The caller is not expected to free or modify the value since this is
returning a reference to a buffer maintained by the upper layer.
Signed-off-by: Jouni Malinen <j@w1.fi>
These are confusing when the style used with the couple of FST IE checks
differs from the rest of hostapd/wpa_supplicant implementation.
Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>
There is no need for this function to be an inline function in a header
file since it is used only within fst_group.c.
Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>
Fast Session Transfer (FST) is the transfer of a session from a channel
to another channel in a different frequency band. The term "session"
refers to non-physical layer state information kept by a pair of
stations (STAs) that communicate directly (i.e., excludes forwarding).
The FST is implemented in accordance with IEEE Std 802.11ad-2012.
Definitions
* FST interface - an interface for which FST functionality is enabled
* FST group - a bunch of FST interfaces representing single
multi-band STA
* FST peer - a multi-band capable STA connected
* FST module - multi-band operation functionality implemented in
accordance with IEEE Std 802.11ad-2012 (see 10.32
Multi-band operation) as a part of hostapd/wpa_supplicant
* FST manager - an external application that implements custom FST
related logic, using the FST module's interfaces
accessible via CLI or D-Bus
This commit introduces only the FST module. Integration of the FST
module into the hostapd/wpa_supplicant and corresponding CLI/D-Bus
interfaces and FST related tests are covered in separate commits.
FST manager application is out of scope of these commits.
As FST aggregates a few interfaces into FST group, the FST module uses
global CLI for both commands and notifications. It also exposes
alternative non-interface based D-Bus subtree for this purposes.
Configuration and Initialization
* FST functionality can enabled by compilation flag (CONFIG_FST)
* hostapd/wpa_supplicant controlling multiple interfaces are used for
FST
* once enabled by compilation, the FST can be enabled for specific
interfaces in the configuration files
* FST interfaces are aggregated in FST groups (fst_group_id config file
entry), where each FST group:
- represents one multi-band device
- should have two or more FST interfaces in it
* priority (fst_priority config file entry) must be configured for each
FST interface. FST interface with higher priority is the interface FST
will always try to switch to. Thus, for example, for the maximal
throughput, it should be the fastest FST interface in the FST setup.
* default Link Loss Timeout (LLT) value can be configured for each FST
interface (fst_llt config file entry). It represents LLT to be used
by FST when this interface is active.
* FST interfaces advertise the Multi-band capability by including the
Multi-band element in the corresponding frames
FST CLI commands:
* fst list_groups - list FST groups configured.
* fst list_ifaces - list FST interfaces which belong to specific group
* fst iface_peers - list Multi-Band STAs connected to specific interface
* fst list_sessions - list existing FST sessions
* fst session_get - get FST session info
* fst session_add - create FST session object
* fst session_set - set FST session parameters (old_iface, new_iface,
peer_addr, llt)
* fst session_initiate - initiate FST setup
* fst session_respond - respond to FST setup establishemnt attempt by
counterpart
* fst session_transfer - initiate FST switch
* fst session_teardown - tear down FST Setup but leave the session object
for reuse
* fst session_remove - remove FST session object
FST CLI notifications:
* FST-EVENT-PEER - peer state changed (CONNECT/DISCONNECT)
* FST-EVENT-SESSION - FST session level notification with following
sub-events:
- EVENT_FST_SESSION_STATE - FST session state changed
- EVENT_FST_ESTABLISHED - previously initiated FST session became
established
- EVENT_FST_SETUP - new FST session object created due to FST session
negotiation attempt by counterpart
All the FST CLI commands and notifications are also implemented on D-Bus
for wpa_supplicant.
IEEE 802.11 standard compliance
FST module implements FST setup statemachine in compliance with IEEE
802.11ad (P802.11-REVmc/D3.3), as it described in 10.32 Multi-band
operation (see also Figure 10-34 - States of the FST setup protocol).
Thus, for example, the FST module initiates FST switch automatically
when FST setup becomes established with LLT=0 in accordance with
10.32.2.2 Transitioning between states.
At the moment, FST module only supports non-transparent STA-based FST
(see 10.32.1 General).
Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>
Jouni Malinen