Treat '' in SSIDs param of DBus Scan as a request for Broadcast scan.

Treat '' in SSIDs param of DBus Scan as a request for Broadcast scan.

This changes wpa_supplicant policy for handling '' in SSIDs field of Interface.SSID DBus message.

Change-Id: I359611ed516303de9a4a6ecabdca6a6be7c05e32

BUG=chromium-os:3623
TEST=MatFunc and SecMat for regression.

For specific Tests, use WiFi sniffer (wireshark). 
On dbus: 
Method:    Scan 
Interface: fi.w1.wpa_supplicant1.Interface.Scan 
Path:      /fi/w1/wpa_supplicant1/Interfaces/1 

Results after both this and patch 3607008:

  1) Request:     Passive scan (all channels)
     Should be:   No ProbeRequests; Passive Scan results for all channels
     Previous:    1 ProbeRequest on all channels for both broadcast SSID and selected network (scan_ssid=1)     
     3607008:     1 ProbeRequest on all channels for both broadcast SSID and selected network (scan_ssid=1)     
     +This Patch: 1 ProbeRequest on all channels for both broadcast SSID and selected network (scan_ssid=1)     
                 

  2) Request:     Passive scan (1 channel)
     Should be:   No ProbeRequests; Passive Scan results for 1 channel (plus overlapping channels)
     Previous:    1 broadcast ProbeRequest on specified channel
     3607008:     No ProbeRequests; Passive Scan results for 1 channel (plus overlapping channels)
     +This Patch: No ProbeRequests; Passive Scan results for 1 channel (plus overlapping channels)

  3) Request:     Active scan with no SSIDs (all channels)
     Should be:   1 broadcast ProbeRequest on all channels
     Previous:    No ProbeRequests;  passive scan results for all channels
     3607008:     1 broadcast ProbeRequest on all channels
     +This Patch: 1 broadcast ProbeRequest on all channels

  4) Request:     Active scan with no SSIDs (1 channel)
     Should be:   1 broadcast ProbeRequest on specified channel
     Previous:    No ProbeRequests; Passive scan results for specified channel (plus overlapping channels)
     3607008:     1 broadcast ProbeRequest on specified channel
     +This Patch: 1 broadcast ProbeRequest on specified channel

  5) Request:     Active scan with only '' SSID (1 channel)
     Should be:   1 broadcast ProbeRequest on specified channel
     Previous:    No ProbeRequests; passive scan results for specified channel
     3607008:     No ProbeRequests; passive scan results for specified channel
     +This Patch: FIXED: 1 broadcast ProbeRequest on specified channel

  6) Request:     Active scan with only non-'' SSIDs (1 channel)
     Should be:   1 directed ProbeRequest for each SSID on specified channel, no broadcast ProbeRequest
     Previous:    1 directed ProbeRequest for each SSID on specified channel, no broadcast ProbeRequest
     3607008:     1 directed ProbeRequest for each SSID on specified channel, no broadcast ProbeRequest
     +This Patch: 1 directed ProbeRequest for each SSID on specified channel, no broadcast ProbeRequest

  7) Request:     Active scan with SSIDs, including 1 '' SSID (1 channel)
     Should be:   1 broadcast ProbeRequest, 1 directed ProbeRequest for each non-'' SSID on specified channel
     Previous:    1 directed ProbeRequest for each non-'' SSID on specified channel
     3607008:     1 directed ProbeRequest for each non-'' SSID on specified channel
     +This Patch: FIXED: 1 broadcast ProbeRequest, 1 directed ProbeRequest for each non-'' SSID on specified channel

Committed: http://chrome-svn/viewvc/chromeos?view=rev&revision=d878c91

[Paul Stewart, 2010-10-06 16:49:59]

LGTM.  Please upstream this change to the hostap list (if you haven't already,
subscribe to hostap@lists.shmoo.com), but first check their git repository to
make sure the change will apply there.  Also, please interleave the "before and
after" results from the other CL here.

[Sam Leffler, 2010-10-06 17:29:29]

http://codereview.chromium.org/3543011/diff/1/2
File wpa_supplicant/dbus/dbus_new_handlers.c (right):

http://codereview.chromium.org/3543011/diff/1/2#newcode1000
wpa_supplicant/dbus/dbus_new_handlers.c:1000: ssid = os_malloc(len);
I find this a bit awkward; perhaps stick the malloc+related code under the if
(len != 0); then you don't need to depend, for example, on memcpy handling ssid
== NULL because len is 0.

[Daniel Kurtz, 2010-10-06 18:10:36]

http://codereview.chromium.org/3543011/diff/1/2
File wpa_supplicant/dbus/dbus_new_handlers.c (right):

http://codereview.chromium.org/3543011/diff/1/2#newcode1000
wpa_supplicant/dbus/dbus_new_handlers.c:1000: ssid = os_malloc(len);
On 2010/10/06 17:29:30, Sam Leffler wrote:
> I find this a bit awkward; perhaps stick the malloc+related code under the if
> (len != 0); then you don't need to depend, for example, on memcpy handling
ssid
> == NULL because len is 0.

Done.

[Sam Leffler, 2010-10-06 18:25:46]

LGTM