Consolidate the code that extract the ip address(src,dst) and
port number(src,dst) of the packet into a separate routine
extract_ip_and_port() since the same chunk of code is called
from two place.

Cc: Zhang Chen <zhangckid@gmail.com>
Cc: Li Zhijian <lizhijian@cn.fujitsu.com>
Cc: Jason Wang <jasowang@redhat.com>
Signed-off-by: Mao Zhongyi <maozy.fnst@cn.fujitsu.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>