qemu.tests: add case virtual_nic_private support

This patch add case virtual nic private support.

change log:
    Change from V1:
        1.add parameters list
        2.delete some default values.
        3.close all sessions after test
        4.make more detailed loginfo.
    Change from V2
        1.modify dd command add oflag=direct
        2.using try..finally to catch exception
    change from V3:
        1.modify data case method, using tcpdump -c to control.
        2.add -i option for tcpdump cmd.
    change from V4:
        1.add new mon funcution.
        2.add more debuginfo
    change from V5:
        1.modify the function data_mon, using only on thread
        2.modify coding style
    change from V6:
        1.modify coding style
        2.modify some typo
        3.add judgement before close the session
Signed-off-by: NYunping Zheng <yunzheng@redhat.com>
Acked-by: NFeng Yang <fyang@redhat.com>

qemu/tests/cfg/virtual_nic_private.cfg

+- virtual_nic_private:
+    virt_test_type = qemu
+    #now this case only support linux guest, will support windows later
+    only Linux
+    type = virtual_nic_private
+    vms = "vm1 vm2 vm3"
+    image_snapshot = yes
+    catch_date = "%s.* > %s.ssh"
+    tcpdump_cmd = "tcpdump -s 0 -n tcp -vv port ssh and dst %s and src %s -i %s "
+    dd_cmd = "dd if=/dev/urandom of=%s oflag=direct bs=1M count=%d"
+    filesize = 100

qemu/tests/virtual_nic_private.py

+import logging, re
+from autotest.client import utils
+from autotest.client.shared import error
+from virttest import remote, utils_misc, utils_net
+from virttest.aexpect import ShellCmdError
+
+@error.context_aware
+def run_virtual_nic_private(test, params, env):
+    """
+    Test Step:
+        1. boot up three virtual machine
+        2. transfer file from guest1 to guest2, check md5
+        3. in guest 3 try to capture the packets(guest1 <-> guest2)
+    Params:
+        @param test: QEMU test object
+        @param params: Dictionary with the test parameters
+        @param env: Dictionary with test environment.
+    """
+    def data_mon(session, cmd, timeout):
+        try:
+            session.cmd(cmd, timeout)
+        except ShellCmdError, e:
+            if re.findall(catch_date % (addresses[1], addresses[0]), str(e)):
+                raise error.TestFail("God! Capture the transfet data:'%s'"
+                                     % str(e))
+            logging.info("Guest3 catch data is '%s'" %  str(e))
+
+
+    timeout = int(params.get("login_timeout", '360'))
+    password = params.get("password")
+    username = params.get("username")
+    shell_port = params.get("shell_port")
+    tmp_dir = params.get("tmp_dir", "/tmp/")
+    clean_cmd = params.get("clean_cmd", "rm -f")
+    filesize = int(params.get("filesize", '100'))
+
+    tcpdump_cmd = params.get("tcpdump_cmd")
+    dd_cmd = params.get("dd_cmd")
+    catch_date = params.get("catch_data", "%s.* > %s.ssh")
+    md5_check = params.get("md5_check", "md5sum %s")
+    mon_process_timeout = int(params.get("mon_process_timeout", "1200"))
+    sessions = []
+    addresses = []
+    vms = []
+
+    error.context("Init boot the vms")
+    for vm_name in params.get("vms", "vm1 vm2 vm3").split():
+        vms.append(env.get_vm(vm_name))
+    for vm in vms :
+        vm.verify_alive()
+        sessions.append(vm.wait_for_login(timeout=timeout))
+        addresses.append(vm.get_address())
+    mon_session =vms[2].wait_for_login(timeout=timeout)
+
+    src_file = (tmp_dir + "src-%s" % utils_misc.generate_random_string(8))
+    dst_file = (tmp_dir + "dst-%s" %  utils_misc.generate_random_string(8))
+
+    try:
+        #Before transfer, run tcpdump to try to catche data
+        error_msg = "In guest3, try to capture the packets(guest1 <-> guest2)"
+        error.context(error_msg, logging.info)
+        interface_name = utils_net.get_linux_ifname(sessions[2],
+                                                     vm.get_mac_address())
+
+        tcpdump_cmd = tcpdump_cmd % (addresses[1], addresses[0],
+                                     interface_name)
+        t = utils.InterruptedThread(data_mon, (sessions[2], tcpdump_cmd,
+                                               mon_process_timeout))
+
+        logging.info("Tcpdump mon start ...")
+        logging.info("Creating %dMB file on guest1", filesize)
+        sessions[0].cmd(dd_cmd  % (src_file, filesize), timeout=timeout)
+        t.start()
+
+        error.context("Transfering file guest1 -> guest2", logging.info)
+        remote.scp_between_remotes(addresses[0], addresses[1],
+                                   shell_port, password, password,
+                                   username, username, src_file, dst_file)
+
+        error.context("Check the src and dst file is same", logging.info)
+        src_md5 = sessions[0].cmd_output(md5_check % src_file).split()[0]
+        dst_md5 = sessions[1].cmd_output(md5_check % dst_file).split()[0]
+
+        if dst_md5 != src_md5:
+            debug_msg = "Files md5sum mismatch!"
+            debug_msg += "source file md5 is '%s', after transfer md5 is '%s'"
+            raise error.TestFail(debug_msg % (src_md5, dst_md5), logging.info)
+        logging.info("Files md5sum match, file md5 is '%s'" % src_md5)
+
+        error.context("Checking network private", logging.info)
+        tcpdump_reg = "tcpdump.*%s.*%s" % (addresses[1], addresses[0])
+        s = mon_session.cmd_status("pgrep -f '%s'" % tcpdump_reg)
+        if s:
+            raise error.TestError("Tcpdump process terminate exceptly")
+        mon_session.cmd("killall -9 tcpdump")
+        t.join()
+
+    finally:
+        sessions[0].cmd(" %s %s " % (clean_cmd, src_file))
+        sessions[1].cmd(" %s %s " % (clean_cmd, src_file))
+        if mon_session:
+            mon_session.close()
+        for session in sessions:
+            if session:
+                session.close()