[dts] [PATCH 2/6] framework packet: only sniff coming packet when tcpdump support

[Yong Liu <yong.liu@intel.com>]

Newer version tcpdump support capture packet by direction. This feature
will help us distinguish coming packets and outgoing packets. And will be
helpful when only one nic available on tester.

Signed-off-by: Marvin Liu <yong.liu@intel.com>

diff --git a/framework/packet.py b/framework/packet.py
index 6d16a9e..aaa1dd0 100755
--- a/framework/packet.py
+++ b/framework/packet.py
@@ -639,8 +639,20 @@ def sniff_packets(intf, count=0, timeout=5):
     """
     sniff all packets for certain port in certain seconds
     """
-    sniff_cmd = 'tcpdump -i %(INTF)s -w %(FILE)s'
-    options = {'INTF': intf, 'COUNT': count,
+    param = ""
+    direct_param = r"(\s+)\[ -(\w) in\|out\|inout \]"
+    tcpdump_help = subprocess.check_output("tcpdump -h; echo 0",
+                        stderr=subprocess.STDOUT, shell=True)
+    for line in tcpdump_help.split('\n'):
+        m = re.match(direct_param, line)
+        if m:
+            param = "-" + m.group(2) + " in"
+
+    if len(param) == 0:
+        print "tcpdump not support direction chioce!!!"
+
+    sniff_cmd = 'tcpdump -i %(INTF)s %(IN_PARAM)s -w %(FILE)s'
+    options = {'INTF': intf, 'COUNT': count, 'IN_PARAM': param,
                'FILE': '/tmp/sniff_%s.pcap' % intf}
     if count:
         sniff_cmd += ' -c %(COUNT)d'
-- 
1.9.3