wireless: sleep on failure to request rescan

In wifi_nmcli_test on recent nmcli versions a rescan is requested to ensure an up-to-date list of APs is available. However this request can fail if NM has already started a scan, but we immediately attempt the connection. This should let the background scan complete. 

1 files changed, 23 insertions, 13 deletions

diff --git a/bin/wifi_nmcli_test b/bin/wifi_nmcli_test.py
index b89a525..45b8624 100755
--- a/bin/wifi_nmcli_test
+++ b/bin/wifi_nmcli_test.py
@@ -1,5 +1,5 @@
 #!/usr/bin/env python3
-# Copyright 2017-2018 Canonical Ltd.
+# Copyright 2017-2019 Canonical Ltd.
 # All rights reserved.
 #
 # Written by:
@@ -13,6 +13,7 @@ import argparse
 import functools
 import subprocess as sp
 import sys
+import time
 
 from distutils.version import LooseVersion
 
@@ -61,7 +62,13 @@ def device_rescan():
 print_head("Calling a rescan")
 cmd = "nmcli d wifi rescan"
 print_cmd(cmd)
- sp.call(cmd, shell=True)
+ retcode = sp.call(cmd, shell=True)
+ if retcode != 0:
+ # Most often the rescan request fails because NM has itself started
+ # a scan in recent past, we should let these operations complete before
+ # attempting a connection
+ print('Scan request failed, allow other operations to complete (15s)')
+ time.sleep(15)
 print()
 
 
@@ -73,7 +80,8 @@ def list_aps(args):
 cmd = "nmcli -t -f {} d wifi list iface {}".format(fields, args.device)
 else:
 fields = "SSID,CHAN,FREQ,SIGNAL"
- cmd = "nmcli -t -f {} d wifi list ifname {}".format(fields, args.device)
+ cmd = "nmcli -t -f {} d wifi list ifname {}".format(
+ fields, args.device)
 print_cmd(cmd)
 output = sp.check_output(cmd, shell=True)
 for line in output.decode(sys.stdout.encoding).splitlines():
@@ -108,10 +116,11 @@ def open_connection(args):
 print_cmd(cmd)
 sp.call(cmd, shell=True)
 if legacy_nmcli():
- cmd_part = "nmcli -m tabular -t -f GENERAL d list | "
- cmd = cmd_part + "grep {} | awk -F: '{{print $15}}'".format(args.device)
+ cmd = ("nmcli -m tabular -t -f GENERAL d list | grep {} | "
+ "awk -F: '{{print $15}}'".format(args.device))
 else:
- cmd = "nmcli -m tabular -t -f GENERAL.STATE d show {}".format(args.device)
+ cmd = "nmcli -m tabular -t -f GENERAL.STATE d show {}".format(
+ args.device)
 print_cmd(cmd)
 output = sp.check_output(cmd, shell=True)
 state = output.decode(sys.stdout.encoding).strip()
@@ -126,18 +135,19 @@ def open_connection(args):
 def secured_connection(args):
 print_head("Connection attempt")
 if legacy_nmcli():
- cmd = "nmcli d wifi connect {} password {} iface {} name TEST_CON".format(
- args.essid, args.psk, args.device)
+ cmd = ("nmcli d wifi connect {} password {} iface {} name "
+ "TEST_CON".format(args.essid, args.psk, args.device))
 else:
- cmd = "nmcli d wifi connect {} password {} ifname {} name TEST_CON".format(
- args.essid, args.psk, args.device)
+ cmd = ("nmcli d wifi connect {} password {} ifname {} name "
+ "TEST_CON".format(args.essid, args.psk, args.device))
 print_cmd(cmd)
 sp.call(cmd, shell=True)
 if legacy_nmcli():
- cmd_part = "nmcli -m tabular -t -f GENERAL d list | "
- cmd = cmd_part + "grep {} | awk -F: '{{print $15}}'".format(args.device)
+ cmd = ("nmcli -m tabular -t -f GENERAL d list | "
+ "grep {} | awk -F: '{{print $15}}'".format(args.device))
 else:
- cmd = "nmcli -m tabular -t -f GENERAL.STATE d show {}".format(args.device)
+ cmd = "nmcli -m tabular -t -f GENERAL.STATE d show {}".format(
+ args.device)
 print_cmd(cmd)
 output = sp.check_output(cmd, shell=True)
 state = output.decode(sys.stdout.encoding).strip()