src/python/oftest/testutils.py

import sys
import copy
import logging
import types
import time
import re
import packet as scapy

import oftest
import oftest.controller
import oftest.dataplane
import oftest.parse
import oftest.ofutils
import ofp

global skipped_test_count
skipped_test_count = 0

_import_blacklist = set(locals().keys())

# Some useful defines
IP_ETHERTYPE = 0x800
TCP_PROTOCOL = 0x6
UDP_PROTOCOL = 0x11

MINSIZE = 0

def delete_all_flows(ctrl, send_barrier=True):
    """
    Delete all flows on the switch
    @param ctrl The controller object for the test
    @param send_barrier Whether or not to send a barrier message
    """

    logging.info("Deleting all flows")
    msg = ofp.message.flow_delete()
    if ofp.OFP_VERSION in [1, 2]:
        msg.match.wildcards = ofp.OFPFW_ALL
        msg.out_port = ofp.OFPP_NONE
        msg.buffer_id = 0xffffffff
    elif ofp.OFP_VERSION >= 3:
        msg.table_id = ofp.OFPTT_ALL
        msg.buffer_id = ofp.OFP_NO_BUFFER
        msg.out_port = ofp.OFPP_ANY
        msg.out_group = ofp.OFPG_ANY
    ctrl.message_send(msg)
    if send_barrier:
        do_barrier(ctrl)
    return 0 # for backwards compatibility

def delete_all_groups(ctrl):
    """
    Delete all groups on the switch
    @param ctrl The controller object for the test
    """

    logging.info("Deleting all groups")
    msg = ofp.message.group_delete(group_id=ofp.OFPG_ALL)
    ctrl.message_send(msg)
    do_barrier(ctrl)

def required_wildcards(parent):
    w = test_param_get('required_wildcards', default='default')
    if w == 'l3-l4':
        return (ofp.OFPFW_NW_SRC_ALL | ofp.OFPFW_NW_DST_ALL | ofp.OFPFW_NW_TOS
                | ofp.OFPFW_NW_PROTO | ofp.OFPFW_TP_SRC | ofp.OFPFW_TP_DST)
    else:
        return 0

def simple_packet(content='00 00 00 11 33 55 00 00 00 11 22 33 81 00 00 03 '
                '08 00 45 00 00 2e 04 d2 00 00 7f 00 b2 47 c0 a8 '
                '01 64 c0 a8 02 02 00 00 00 00 00 00 00 00 00 00 '
                '00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00'):
             
    pkt = ''.join(content.split(" ")).decode('hex')
    pkt = scapy.Ether(pkt)
    if len(pkt) < 64:
        pkt = pkt/("D" * (64 - len(pkt)))
    #scapy.hexdump(pkt)
    return pkt

def simple_tcp_packet(pktlen=100, 
                      eth_dst='00:01:02:03:04:05',
                      eth_src='00:06:07:08:09:0a',
                      dl_vlan_enable=False,
                      vlan_vid=0,
                      vlan_pcp=0,
                      dl_vlan_cfi=0,
                      ip_src='192.168.0.1',
                      ip_dst='192.168.0.2',
                      ip_tos=0,
                      ip_ttl=64,
                      tcp_sport=1234,
                      tcp_dport=80,
                      tcp_flags="S",
                      ip_ihl=None,
                      ip_options=False
                      ):
    """
    Return a simple dataplane TCP packet

    Supports a few parameters:
    @param len Length of packet in bytes w/o CRC
    @param eth_dst Destinatino MAC
    @param eth_src Source MAC
    @param dl_vlan_enable True if the packet is with vlan, False otherwise
    @param vlan_vid VLAN ID
    @param vlan_pcp VLAN priority
    @param ip_src IP source
    @param ip_dst IP destination
    @param ip_tos IP ToS
    @param ip_ttl IP TTL
    @param tcp_dport TCP destination port
    @param tcp_sport TCP source port
    @param tcp_flags TCP Control flags  	

    Generates a simple TCP request.  Users
    shouldn't assume anything about this packet other than that
    it is a valid ethernet/IP/TCP frame.
    """

    if MINSIZE > pktlen:
        pktlen = MINSIZE

    # Note Dot1Q.id is really CFI
    if (dl_vlan_enable):
        pkt = scapy.Ether(dst=eth_dst, src=eth_src)/ \
            scapy.Dot1Q(prio=vlan_pcp, id=dl_vlan_cfi, vlan=vlan_vid)/ \
            scapy.IP(src=ip_src, dst=ip_dst, tos=ip_tos, ttl=ip_ttl, ihl=ip_ihl)/ \
            scapy.TCP(sport=tcp_sport, dport=tcp_dport, flags=tcp_flags)
    else:
        if not ip_options:
            pkt = scapy.Ether(dst=eth_dst, src=eth_src)/ \
                scapy.IP(src=ip_src, dst=ip_dst, tos=ip_tos, ttl=ip_ttl, ihl=ip_ihl)/ \
                scapy.TCP(sport=tcp_sport, dport=tcp_dport, flags=tcp_flags)
        else:
            pkt = scapy.Ether(dst=eth_dst, src=eth_src)/ \
                scapy.IP(src=ip_src, dst=ip_dst, tos=ip_tos, ttl=ip_ttl, ihl=ip_ihl, options=ip_options)/ \
                scapy.TCP(sport=tcp_sport, dport=tcp_dport, flags=tcp_flags)

    pkt = pkt/("D" * (pktlen - len(pkt)))

    return pkt

def simple_tcpv6_packet(pktlen=100,
                        eth_dst='00:01:02:03:04:05',
                        eth_src='00:06:07:08:09:0a',
                        dl_vlan_enable=False,
                        vlan_vid=0,
                        vlan_pcp=0,
                        ipv6_src='2001:db8:85a3::8a2e:370:7334',
                        ipv6_dst='2001:db8:85a3::8a2e:370:7335',
                        ipv6_tc=0,
                        ipv6_hlim=64,
                        ipv6_fl=0,
                        tcp_sport=1234,
                        tcp_dport=80,
                        tcp_flags="S"):
    """
    Return a simple IPv6/TCP packet

    Supports a few parameters:
    @param len Length of packet in bytes w/o CRC
    @param eth_dst Destination MAC
    @param eth_src Source MAC
    @param dl_vlan_enable True if the packet is with vlan, False otherwise
    @param vlan_vid VLAN ID
    @param vlan_pcp VLAN priority
    @param ipv6_src IPv6 source
    @param ipv6_dst IPv6 destination
    @param ipv6_tc IPv6 traffic class
    @param ipv6_ttl IPv6 hop limit
    @param ipv6_fl IPv6 flow label
    @param tcp_dport TCP destination port
    @param tcp_sport TCP source port
    @param tcp_flags TCP Control flags	

    Generates a simple TCP request. Users shouldn't assume anything about this
    packet other than that it is a valid ethernet/IPv6/TCP frame.
    """

    if MINSIZE > pktlen:
        pktlen = MINSIZE

    pkt = scapy.Ether(dst=eth_dst, src=eth_src)
    if dl_vlan_enable or vlan_vid or vlan_pcp:
        pkt /= scapy.Dot1Q(vlan=vlan_vid, prio=vlan_pcp)
    pkt /= scapy.IPv6(src=ipv6_src, dst=ipv6_dst, fl=ipv6_fl, tc=ipv6_tc, hlim=ipv6_hlim)
    pkt /= scapy.TCP(sport=tcp_sport, dport=tcp_dport, flags=tcp_flags)
    pkt /= ("D" * (pktlen - len(pkt)))

    return pkt

def simple_udp_packet(pktlen=100,
                      eth_dst='00:01:02:03:04:05',
                      eth_src='00:06:07:08:09:0a',
                      dl_vlan_enable=False,
                      vlan_vid=0,
                      vlan_pcp=0,
                      dl_vlan_cfi=0,
                      ip_src='192.168.0.1',
                      ip_dst='192.168.0.2',
                      ip_tos=0,
                      ip_ttl=64,
                      udp_sport=1234,
                      udp_dport=80,
                      ip_ihl=None,
                      ip_options=False
                      ):
    """
    Return a simple dataplane UDP packet

    Supports a few parameters:
    @param len Length of packet in bytes w/o CRC
    @param eth_dst Destination MAC
    @param eth_src Source MAC
    @param dl_vlan_enable True if the packet is with vlan, False otherwise
    @param vlan_vid VLAN ID
    @param vlan_pcp VLAN priority
    @param ip_src IP source
    @param ip_dst IP destination
    @param ip_tos IP ToS
    @param ip_ttl IP TTL
    @param udp_dport UDP destination port
    @param udp_sport UDP source port

    Generates a simple UDP packet. Users shouldn't assume anything about
    this packet other than that it is a valid ethernet/IP/UDP frame.
    """

    if MINSIZE > pktlen:
        pktlen = MINSIZE

    # Note Dot1Q.id is really CFI
    if (dl_vlan_enable):
        pkt = scapy.Ether(dst=eth_dst, src=eth_src)/ \
            scapy.Dot1Q(prio=vlan_pcp, id=dl_vlan_cfi, vlan=vlan_vid)/ \
            scapy.IP(src=ip_src, dst=ip_dst, tos=ip_tos, ttl=ip_ttl, ihl=ip_ihl)/ \
            scapy.UDP(sport=udp_sport, dport=udp_dport)
    else:
        if not ip_options:
            pkt = scapy.Ether(dst=eth_dst, src=eth_src)/ \
                scapy.IP(src=ip_src, dst=ip_dst, tos=ip_tos, ttl=ip_ttl, ihl=ip_ihl)/ \
                scapy.UDP(sport=udp_sport, dport=udp_dport)
        else:
            pkt = scapy.Ether(dst=eth_dst, src=eth_src)/ \
                scapy.IP(src=ip_src, dst=ip_dst, tos=ip_tos, ttl=ip_ttl, ihl=ip_ihl, options=ip_options)/ \
                scapy.UDP(sport=udp_sport, dport=udp_dport)

    pkt = pkt/("D" * (pktlen - len(pkt)))

    return pkt


def simple_tcp_packet_two_vlan(pktlen=100, 
                      eth_dst='00:01:02:03:04:05',
                      eth_src='00:06:07:08:09:0a',
                      out_dl_vlan_enable=False,
                      in_dl_vlan_enable=False,
                      out_vlan_vid=0,
                      out_vlan_pcp=0,
                      out_dl_vlan_cfi=0,                      
                      in_vlan_vid=0,
                      in_vlan_pcp=0,  
                      in_dl_vlan_cfi=0,
                      ip_src='192.168.0.1',
                      ip_dst='192.168.0.2',
                      ip_tos=0,
                      ip_ttl=64,
                      tcp_sport=1234,
                      tcp_dport=80,
                      tcp_flags="S",
                      ip_ihl=None,
                      ip_options=False
                      ):
    """
    Return a simple dataplane TCP packet

    Supports a few parameters:
    @param len Length of packet in bytes w/o CRC
    @param eth_dst Destinatino MAC
    @param eth_src Source MAC
    @param dl_vlan_enable True if the packet is with vlan, False otherwise
    @param vlan_vid VLAN ID
    @param vlan_pcp VLAN priority
    @param ip_src IP source
    @param ip_dst IP destination
    @param ip_tos IP ToS
    @param ip_ttl IP TTL
    @param tcp_dport TCP destination port
    @param tcp_sport TCP source port
    @param tcp_flags TCP Control flags  	

    Generates a simple TCP request.  Users
    shouldn't assume anything about this packet other than that
    it is a valid ethernet/IP/TCP frame.
    """

    if MINSIZE > pktlen:
        pktlen = MINSIZE

    # Note Dot1Q.id is really CFI
    if (out_dl_vlan_enable and in_dl_vlan_enable):
        pkt = scapy.Ether(dst=eth_dst, src=eth_src)/ \
            scapy.Dot1Q(prio=out_vlan_pcp, id=out_dl_vlan_cfi, vlan=out_vlan_vid)

        if in_dl_vlan_enable:
            pkt = pkt/scapy.Dot1Q(prio=in_vlan_pcp, id=in_dl_vlan_cfi, vlan=in_vlan_vid)

        pkt = pkt/scapy.IP(src=ip_src, dst=ip_dst, tos=ip_tos, ttl=ip_ttl, ihl=ip_ihl)/ \
            scapy.TCP(sport=tcp_sport, dport=tcp_dport, flags=tcp_flags)
    elif (out_dl_vlan_enable and (not in_dl_vlan_enable)):
        pkt = scapy.Ether(dst=eth_dst, src=eth_src)/ \
            scapy.Dot1Q(prio=out_vlan_pcp, id=out_dl_vlan_cfi, vlan=out_vlan_vid)/ \
            scapy.IP(src=ip_src, dst=ip_dst, tos=ip_tos, ttl=ip_ttl, ihl=ip_ihl)/ \
            scapy.TCP(sport=tcp_sport, dport=tcp_dport, flags=tcp_flags)
    elif ((not out_dl_vlan_enable) and in_dl_vlan_enable):
        assert(0) #shall not have this caes
    else:
        if not ip_options:
            pkt = scapy.Ether(dst=eth_dst, src=eth_src)/ \
                scapy.IP(src=ip_src, dst=ip_dst, tos=ip_tos, ttl=ip_ttl, ihl=ip_ihl)/ \
                scapy.TCP(sport=tcp_sport, dport=tcp_dport, flags=tcp_flags)
        else:
            pkt = scapy.Ether(dst=eth_dst, src=eth_src)/ \
                scapy.IP(src=ip_src, dst=ip_dst, tos=ip_tos, ttl=ip_ttl, ihl=ip_ihl, options=ip_options)/ \
                scapy.TCP(sport=tcp_sport, dport=tcp_dport, flags=tcp_flags)

    pkt = pkt/("D" * (pktlen - len(pkt)))

    return pkt

def simple_vxlan_packet(eth_dst='00:01:02:03:04:05',
                      eth_src='00:06:07:08:09:0a',
                      dl_vlan_enable=False,
                      vlan_vid=0,
                      vlan_pcp=0,
                      dl_vlan_cfi=0,
                      ip_src='192.168.0.1',
                      ip_dst='192.168.0.2',
                      ip_tos=0,
                      ip_ttl=64,
                      udp_sport=1234,
                      udp_dport=4789,
                      vnid=1,
                      inner_payload=None,
                      ip_ihl=None,
                      ip_options=False
                      ):
    """
    Return a simple dataplane UDP packet

    Supports a few parameters:
    @param len Length of packet in bytes w/o CRC
    @param eth_dst Destination MAC
    @param eth_src Source MAC
    @param dl_vlan_enable True if the packet is with vlan, False otherwise
    @param vlan_vid VLAN ID
    @param vlan_pcp VLAN priority
    @param ip_src IP source
    @param ip_dst IP destination
    @param ip_tos IP ToS
    @param ip_ttl IP TTL
    @param udp_dport UDP destination port
    @param udp_sport UDP source port
    @param inner_pyload inner pacekt content
    Generates a simple UDP packet. Users shouldn't assume anything about
    this packet other than that it is a valid ethernet/IP/UDP frame.
    """

    # Note Dot1Q.id is really CFI
    if (dl_vlan_enable):
        pkt = scapy.Ether(dst=eth_dst, src=eth_src)/ \
            scapy.Dot1Q(prio=vlan_pcp, id=dl_vlan_cfi, vlan=vlan_vid)/ \
            scapy.IP(src=ip_src, dst=ip_dst, tos=ip_tos, ttl=ip_ttl, ihl=ip_ihl)/ \
            scapy.UDP(sport=udp_sport, dport=udp_dport)
    else:
        if not ip_options:
            pkt = scapy.Ether(dst=eth_dst, src=eth_src)/ \
                scapy.IP(src=ip_src, dst=ip_dst, tos=ip_tos, ttl=ip_ttl, ihl=ip_ihl)/ \
                scapy.UDP(sport=udp_sport, dport=udp_dport)
        else:
            pkt = scapy.Ether(dst=eth_dst, src=eth_src)/ \
                scapy.IP(src=ip_src, dst=ip_dst, tos=ip_tos, ttl=ip_ttl, ihl=ip_ihl, options=ip_options)/ \
                scapy.UDP(sport=udp_sport, dport=udp_dport)

    #add vxlan header
    pkt = pkt/scapy.VXLAN(vni=vnid)
    #add innder payload
    if inner_payload!=None:
        pkt=pkt/inner_payload

    return pkt

def mpls_packet(pktlen=100, 
                      eth_dst='00:01:02:03:04:05',
                      eth_src='00:06:07:08:09:0a',
                      dl_vlan_enable=False,
                      vlan_vid=0,
                      vlan_pcp=0,
                      dl_vlan_cfi=0,
                      ip_src='192.168.0.1',
                      ip_dst='192.168.0.2',
                      ip_tos=0,
                      ip_ttl=64,
                      tcp_sport=1234,
                      tcp_dport=80,
                      tcp_flags="S",
                      ip_ihl=None,
                      ip_options=False,
                      label=None,
                      inner_payload=True
                      ):
    if MINSIZE > pktlen:
        pktlen = MINSIZE

    # Note Dot1Q.id is really CFI
    if (dl_vlan_enable):
        pkt = scapy.Ether(dst=eth_dst, src=eth_src)/ \
            scapy.Dot1Q(prio=vlan_pcp, id=dl_vlan_cfi, vlan=vlan_vid)
    else:
        pkt = scapy.Ether(dst=eth_dst, src=eth_src)

    #add MPLS header
    for i in range(len(label)):
        l,c,s,t=label[i]    
        pkt = pkt/scapy.MPLS(label=l, cos=c, s=s, ttl=t)

    #add innder payload
    if inner_payload!=None:
        pkt=pkt / \
            scapy.IP(src=ip_src, dst=ip_dst, tos=ip_tos, ttl=ip_ttl, ihl=ip_ihl)/ \
            scapy.TCP(sport=tcp_sport, dport=tcp_dport, flags=tcp_flags)
    
    pkt = pkt/("D" * (pktlen - len(pkt)))

    return pkt

def simple_mpls_packet(eth_dst='00:01:02:03:04:05',
                      eth_src='00:06:07:08:09:0a',
                      dl_vlan_enable=False,
                      vlan_vid=0,
                      vlan_pcp=0,
                      dl_vlan_cfi=0,
                      label=None,
                      inner_payload=None
                      ):
    """
    Return a simple dataplane MPLS packet

    Supports a few parameters:
    @param len Length of packet in bytes w/o CRC
    @param eth_dst Destination MAC
    @param eth_src Source MAC
    @param dl_vlan_enable True if the packet is with vlan, False otherwise
    @param vlan_vid VLAN ID
    @param vlan_pcp VLAN priority
    @param inner_pyload inner pacekt content
    Generates a simple MPLS packet. Users shouldn't assume anything about
    this packet other than that it is a valid ethernet/IP/UDP frame.
    """

    # Note Dot1Q.id is really CFI
    if (dl_vlan_enable):
        pkt = scapy.Ether(dst=eth_dst, src=eth_src)/ \
            scapy.Dot1Q(prio=vlan_pcp, id=dl_vlan_cfi, vlan=vlan_vid)
    else:
        pkt = scapy.Ether(dst=eth_dst, src=eth_src)

    #add MPLS header
    for i in range(len(label)):
        l,c,s,t=label[i]    
        pkt = pkt/scapy.MPLS(label=l, cos=c, s=s, ttl=t)

    #add innder payload
    if inner_payload!=None:
        pkt=pkt/inner_payload

    return pkt
    
def simple_udpv6_packet(pktlen=100,
                        eth_dst='00:01:02:03:04:05',
                        eth_src='00:06:07:08:09:0a',
                        dl_vlan_enable=False,
                        vlan_vid=0,
                        vlan_pcp=0,
                        ipv6_src='2001:db8:85a3::8a2e:370:7334',
                        ipv6_dst='2001:db8:85a3::8a2e:370:7335',
                        ipv6_tc=0,
                        ipv6_hlim=64,
                        ipv6_fl=0,
                        udp_sport=1234,
                        udp_dport=80):
    """
    Return a simple IPv6/UDP packet

    Supports a few parameters:
    @param len Length of packet in bytes w/o CRC
    @param eth_dst Destination MAC
    @param eth_src Source MAC
    @param dl_vlan_enable True if the packet is with vlan, False otherwise
    @param vlan_vid VLAN ID
    @param vlan_pcp VLAN priority
    @param ipv6_src IPv6 source
    @param ipv6_dst IPv6 destination
    @param ipv6_tc IPv6 traffic class
    @param ipv6_ttl IPv6 hop limit
    @param ipv6_fl IPv6 flow label
    @param udp_dport UDP destination port
    @param udp_sport UDP source port

    Generates a simple UDP request. Users shouldn't assume anything about this
    packet other than that it is a valid ethernet/IPv6/UDP frame.
    """

    if MINSIZE > pktlen:
        pktlen = MINSIZE

    pkt = scapy.Ether(dst=eth_dst, src=eth_src)
    if dl_vlan_enable or vlan_vid or vlan_pcp:
        pkt /= scapy.Dot1Q(vlan=vlan_vid, prio=vlan_pcp)
    pkt /= scapy.IPv6(src=ipv6_src, dst=ipv6_dst, fl=ipv6_fl, tc=ipv6_tc, hlim=ipv6_hlim)
    pkt /= scapy.UDP(sport=udp_sport, dport=udp_dport)
    pkt /= ("D" * (pktlen - len(pkt)))

    return pkt

def simple_icmp_packet(pktlen=60, 
                      eth_dst='00:01:02:03:04:05',
                      eth_src='00:06:07:08:09:0a',
                      dl_vlan_enable=False,
                      vlan_vid=0,
                      vlan_pcp=0,
                      ip_src='192.168.0.1',
                      ip_dst='192.168.0.2',
                      ip_tos=0,
                      ip_ttl=64,
                      ip_id=1,  
                      icmp_type=8,
                      icmp_code=0,
                      icmp_data=''):
    """
    Return a simple ICMP packet

    Supports a few parameters:
    @param len Length of packet in bytes w/o CRC
    @param eth_dst Destinatino MAC
    @param eth_src Source MAC
    @param dl_vlan_enable True if the packet is with vlan, False otherwise
    @param vlan_vid VLAN ID
    @param vlan_pcp VLAN priority
    @param ip_src IP source
    @param ip_dst IP destination
    @param ip_tos IP ToS
    @param ip_ttl IP TTL
    @param ip_id IP Identification
    @param icmp_type ICMP type
    @param icmp_code ICMP code
    @param icmp_data ICMP data

    Generates a simple ICMP ECHO REQUEST.  Users
    shouldn't assume anything about this packet other than that
    it is a valid ethernet/ICMP frame.
    """

    if MINSIZE > pktlen:
        pktlen = MINSIZE

    if (dl_vlan_enable):
        pkt = scapy.Ether(dst=eth_dst, src=eth_src)/ \
            scapy.Dot1Q(prio=vlan_pcp, id=0, vlan=vlan_vid)/ \
            scapy.IP(src=ip_src, dst=ip_dst, ttl=ip_ttl, tos=ip_tos, id=ip_id)/ \
            scapy.ICMP(type=icmp_type, code=icmp_code)/ icmp_data
    else:
        pkt = scapy.Ether(dst=eth_dst, src=eth_src)/ \
            scapy.IP(src=ip_src, dst=ip_dst, ttl=ip_ttl, tos=ip_tos, id=ip_id)/ \
            scapy.ICMP(type=icmp_type, code=icmp_code)/ icmp_data

    pkt = pkt/("0" * (pktlen - len(pkt)))

    return pkt

def simple_icmpv6_packet(pktlen=100,
                         eth_dst='00:01:02:03:04:05',
                         eth_src='00:06:07:08:09:0a',
                         dl_vlan_enable=False,
                         vlan_vid=0,
                         vlan_pcp=0,
                         ipv6_src='2001:db8:85a3::8a2e:370:7334',
                         ipv6_dst='2001:db8:85a3::8a2e:370:7335',
                         ipv6_tc=0,
                         ipv6_hlim=64,
                         ipv6_fl=0,
                         icmp_type=8,
                         icmp_code=0):
    """
    Return a simple ICMPv6 packet

    Supports a few parameters:
    @param len Length of packet in bytes w/o CRC
    @param eth_dst Destination MAC
    @param eth_src Source MAC
    @param dl_vlan_enable True if the packet is with vlan, False otherwise
    @param vlan_vid VLAN ID
    @param vlan_pcp VLAN priority
    @param ipv6_src IPv6 source
    @param ipv6_dst IPv6 destination
    @param ipv6_tc IPv6 traffic class
    @param ipv6_ttl IPv6 hop limit
    @param ipv6_fl IPv6 flow label
    @param icmp_type ICMP type
    @param icmp_code ICMP code

    Generates a simple ICMP ECHO REQUEST. Users shouldn't assume anything
    about this packet other than that it is a valid ethernet/IPv6/ICMP frame.
    """

    if MINSIZE > pktlen:
        pktlen = MINSIZE

    pkt = scapy.Ether(dst=eth_dst, src=eth_src)
    if dl_vlan_enable or vlan_vid or vlan_pcp:
        pkt /= scapy.Dot1Q(vlan=vlan_vid, prio=vlan_pcp)
    pkt /= scapy.IPv6(src=ipv6_src, dst=ipv6_dst, fl=ipv6_fl, tc=ipv6_tc, hlim=ipv6_hlim)
    pkt /= scapy.ICMPv6Unknown(type=icmp_type, code=icmp_code)
    pkt /= ("D" * (pktlen - len(pkt)))

    return pkt

def simple_arp_packet(pktlen=60, 
                      eth_dst='ff:ff:ff:ff:ff:ff',
                      eth_src='00:06:07:08:09:0a',
                      vlan_vid=0,
                      vlan_pcp=0,
                      arp_op=1,
                      ip_snd='192.168.0.1',
                      ip_tgt='192.168.0.2',
                      hw_snd='00:06:07:08:09:0a',
                      hw_tgt='00:00:00:00:00:00',
                      ):
    """
    Return a simple ARP packet

    Supports a few parameters:
    @param len Length of packet in bytes w/o CRC
    @param eth_dst Destinatino MAC
    @param eth_src Source MAC
    @param arp_op Operation (1=request, 2=reply)
    @param ip_snd Sender IP
    @param ip_tgt Target IP
    @param hw_snd Sender hardware address
    @param hw_tgt Target hardware address

    Generates a simple ARP REQUEST.  Users
    shouldn't assume anything about this packet other than that
    it is a valid ethernet/ARP frame.
    """

    if MINSIZE > pktlen:
        pktlen = MINSIZE

    pkt = scapy.Ether(dst=eth_dst, src=eth_src)
    if vlan_vid or vlan_pcp:
        pkt /= scapy.Dot1Q(vlan=vlan_vid, prio=vlan_pcp)
    pkt /= scapy.ARP(hwsrc=hw_snd, hwdst=hw_tgt, pdst=ip_tgt, psrc=ip_snd, op=arp_op)

    pkt = pkt/("\0" * (pktlen - len(pkt)))

    return pkt

def simple_eth_packet(pktlen=60,
                      eth_dst='00:01:02:03:04:05',
                      eth_src='00:06:07:08:09:0a',
                      eth_type=0x88cc):

    if MINSIZE > pktlen:
        pktlen = MINSIZE

    pkt = scapy.Ether(dst=eth_dst, src=eth_src, type=eth_type)

    pkt = pkt/("0" * (pktlen - len(pkt)))

    return pkt

def qinq_tcp_packet(pktlen=100, 
                    eth_dst='00:01:02:03:04:05',
                    eth_src='00:06:07:08:09:0a',
                    dl_vlan_outer=20,
                    dl_vlan_pcp_outer=0,
                    dl_vlan_cfi_outer=0,
                    vlan_vid=10,
                    vlan_pcp=0,
                    dl_vlan_cfi=0,
                    ip_src='192.168.0.1',
                    ip_dst='192.168.0.2',
                    ip_tos=0,
                    ip_ttl=64,
                    tcp_sport=1234,
                    tcp_dport=80,
                    ip_ihl=None,
                    ip_options=False
                    ):
    """
    Return a doubly tagged dataplane TCP packet

    Supports a few parameters:
    @param len Length of packet in bytes w/o CRC
    @param eth_dst Destinatino MAC
    @param eth_src Source MAC
    @param dl_vlan_outer Outer VLAN ID
    @param dl_vlan_pcp_outer Outer VLAN priority
    @param dl_vlan_cfi_outer Outer VLAN cfi bit
    @param vlan_vid Inner VLAN ID
    @param vlan_pcp VLAN priority
    @param dl_vlan_cfi VLAN cfi bit
    @param ip_src IP source
    @param ip_dst IP destination
    @param ip_tos IP ToS
    @param tcp_dport TCP destination port
    @param ip_sport TCP source port

    Generates a TCP request.  Users
    shouldn't assume anything about this packet other than that
    it is a valid ethernet/IP/TCP frame.
    """

    if MINSIZE > pktlen:
        pktlen = MINSIZE

    # Note Dot1Q.id is really CFI
    pkt = scapy.Ether(dst=eth_dst, src=eth_src)/ \
          scapy.Dot1Q(prio=dl_vlan_pcp_outer, id=dl_vlan_cfi_outer, vlan=dl_vlan_outer)/ \
          scapy.Dot1Q(prio=vlan_pcp, id=dl_vlan_cfi, vlan=vlan_vid)/ \
          scapy.IP(src=ip_src, dst=ip_dst, tos=ip_tos, ttl=ip_ttl, ihl=ip_ihl)/ \
          scapy.TCP(sport=tcp_sport, dport=tcp_dport)

    pkt = pkt/("D" * (pktlen - len(pkt)))

    return pkt

def do_barrier(ctrl, timeout=-1):
    """
    Do a barrier command
    Return 0 on success, -1 on error
    """
    b = ofp.message.barrier_request()
    (resp, pkt) = ctrl.transact(b, timeout=timeout)
    if resp is None:
        raise AssertionError("barrier failed")
    # We'll trust the transaction processing in the controller that xid matched
    return 0 # for backwards compatibility

def port_config_get(controller, port_no):
    """
    Get a port's configuration

    Gets the switch feature configuration and grabs one port's
    configuration

    @returns (hwaddr, config, advert) The hwaddress, configuration and
    advertised values
    """

    if ofp.OFP_VERSION <= 3:
        request = ofp.message.features_request()
        reply, _ = controller.transact(request)
        if reply is None:
            logging.warn("Get feature request failed")
            return None, None, None
        logging.debug(reply.show())
        ports = reply.ports
    else:
        request = ofp.message.port_desc_stats_request()
        # TODO do multipart correctly
        reply, _ = controller.transact(request)
        if reply is None:
            logging.warn("Port desc stats request failed")
            return None, None, None
        logging.debug(reply.show())
        ports = reply.entries

    for port in ports:
        if port.port_no == port_no:
            return (port.hw_addr, port.config, port.advertised)
    
    logging.warn("Did not find port number for port config")
    return None, None, None

def port_config_set(controller, port_no, config, mask):
    """
    Set the port configuration according the given parameters

    Gets the switch feature configuration and updates one port's
    configuration value according to config and mask
    """
    logging.info("Setting port " + str(port_no) + " to config " + str(config))

    hw_addr, _, _ = port_config_get(controller, port_no)

    mod = ofp.message.port_mod()
    mod.port_no = port_no
    if hw_addr != None:
        mod.hw_addr = hw_addr
    mod.config = config
    mod.mask = mask
    mod.advertise = 0 # No change
    controller.message_send(mod)
    return 0

def receive_pkt_check(dp, pkt, yes_ports, no_ports, assert_if):
    """
    Check for proper receive packets across all ports
    @param dp The dataplane object
    @param pkt Expected packet; may be None if yes_ports is empty
    @param yes_ports Set or list of ports that should recieve packet
    @param no_ports Set or list of ports that should not receive packet
    @param assert_if Object that implements assertXXX

    DEPRECATED in favor in verify_packets
    """

    exp_pkt_arg = None
    if oftest.config["relax"]:
        exp_pkt_arg = pkt

    for ofport in yes_ports:
        logging.debug("Checking for pkt on port " + str(ofport))
        (rcv_port, rcv_pkt, pkt_time) = dp.poll(
            port_number=ofport, exp_pkt=exp_pkt_arg)
        assert_if.assertTrue(rcv_pkt is not None, 
                             "Did not receive pkt on " + str(ofport))
        if not oftest.dataplane.match_exp_pkt(pkt, rcv_pkt):
            logging.debug("Expected %s" % format_packet(pkt))
            logging.debug("Received %s" % format_packet(rcv_pkt))
        assert_if.assertTrue(oftest.dataplane.match_exp_pkt(pkt, rcv_pkt),
                             "Received packet does not match expected packet " +
                             "on port " + str(ofport))
    if len(no_ports) > 0:
        time.sleep(oftest.ofutils.default_negative_timeout)
    for ofport in no_ports:
        logging.debug("Negative check for pkt on port " + str(ofport))
        (rcv_port, rcv_pkt, pkt_time) = dp.poll(
            port_number=ofport, timeout=0, exp_pkt=exp_pkt_arg)
        assert_if.assertTrue(rcv_pkt is None, 
                             "Unexpected pkt on port " + str(ofport))


def receive_pkt_verify(parent, egr_ports, exp_pkt, ing_port):
    """
    Receive a packet and verify it matches an expected value
    @param egr_port A single port or list of ports

    parent must implement dataplane, assertTrue and assertEqual

    DEPRECATED in favor in verify_packets
    """
    exp_pkt_arg = None
    if oftest.config["relax"]:
        exp_pkt_arg = exp_pkt

    if type(egr_ports) == type([]):
        egr_port_list = egr_ports
    else:
        egr_port_list = [egr_ports]

    # Expect a packet from each port on egr port list
    for egr_port in egr_port_list:
        check_port = egr_port
        if egr_port == ofp.OFPP_IN_PORT:
            check_port = ing_port
        (rcv_port, rcv_pkt, pkt_time) = parent.dataplane.poll(
            port_number=check_port, exp_pkt=exp_pkt_arg)

        if rcv_pkt is None:
            logging.error("ERROR: No packet received from " + 
                                str(check_port))

        parent.assertTrue(rcv_pkt is not None,
                          "Did not receive packet port " + str(check_port))
        logging.debug("Packet len " + str(len(rcv_pkt)) + " in on " + 
                            str(rcv_port))

        if str(exp_pkt) != str(rcv_pkt):
            logging.error("ERROR: Packet match failed.")
            logging.debug("Expected len " + str(len(exp_pkt)) + ": "
                                + str(exp_pkt).encode('hex'))
            logging.debug("Received len " + str(len(rcv_pkt)) + ": "
                                + str(rcv_pkt).encode('hex'))
            logging.debug("Expected packet: " + inspect_packet(scapy.Ether(str(exp_pkt))))
            logging.debug("Received packet: " + inspect_packet(scapy.Ether(str(rcv_pkt))))
        parent.assertEqual(str(exp_pkt), str(rcv_pkt),
                           "Packet match error on port " + str(check_port))

def match_verify(parent, req_match, res_match):
    """
    Verify flow matches agree; if they disagree, report where

    parent must implement assertEqual
    Use str() to ensure content is compared and not pointers
    """

    parent.assertEqual(req_match.wildcards, res_match.wildcards,
                       'Match failed: wildcards: ' + hex(req_match.wildcards) +
                       " != " + hex(res_match.wildcards))
    parent.assertEqual(req_match.in_port, res_match.in_port,
                       'Match failed: in_port: ' + str(req_match.in_port) +
                       " != " + str(res_match.in_port))
    parent.assertEqual(str(req_match.eth_src), str(res_match.eth_src),
                       'Match failed: eth_src: ' + str(req_match.eth_src) +
                       " != " + str(res_match.eth_src))
    parent.assertEqual(str(req_match.eth_dst), str(res_match.eth_dst),
                       'Match failed: eth_dst: ' + str(req_match.eth_dst) +
                       " != " + str(res_match.eth_dst))
    parent.assertEqual(req_match.vlan_vid, res_match.vlan_vid,
                       'Match failed: vlan_vid: ' + str(req_match.vlan_vid) +
                       " != " + str(res_match.vlan_vid))
    parent.assertEqual(req_match.vlan_pcp, res_match.vlan_pcp,
                       'Match failed: vlan_pcp: ' + 
                       str(req_match.vlan_pcp) + " != " + 
                       str(res_match.vlan_pcp))
    parent.assertEqual(req_match.eth_type, res_match.eth_type,
                       'Match failed: eth_type: ' + str(req_match.eth_type) +
                       " != " + str(res_match.eth_type))

    if (not(req_match.wildcards & ofp.OFPFW_DL_TYPE)
        and (req_match.eth_type == IP_ETHERTYPE)):
        parent.assertEqual(req_match.ip_dscp, res_match.ip_dscp,
                           'Match failed: ip_dscp: ' + str(req_match.ip_dscp) +
                           " != " + str(res_match.ip_dscp))
        parent.assertEqual(req_match.ip_proto, res_match.ip_proto,
                           'Match failed: ip_proto: ' + str(req_match.ip_proto) +
                           " != " + str(res_match.ip_proto))
        parent.assertEqual(req_match.ipv4_src, res_match.ipv4_src,
                           'Match failed: ipv4_src: ' + str(req_match.ipv4_src) +
                           " != " + str(res_match.ipv4_src))
        parent.assertEqual(req_match.ipv4_dst, res_match.ipv4_dst,
                           'Match failed: ipv4_dst: ' + str(req_match.ipv4_dst) +
                           " != " + str(res_match.ipv4_dst))

        if (not(req_match.wildcards & ofp.OFPFW_NW_PROTO)
            and ((req_match.ip_proto == TCP_PROTOCOL)
                 or (req_match.ip_proto == UDP_PROTOCOL))):
            parent.assertEqual(req_match.tcp_src, res_match.tcp_src,
                               'Match failed: tcp_src: ' + 
                               str(req_match.tcp_src) +
                               " != " + str(res_match.tcp_src))
            parent.assertEqual(req_match.tcp_dst, res_match.tcp_dst,
                               'Match failed: tcp_dst: ' + 
                               str(req_match.tcp_dst) +
                               " != " + str(res_match.tcp_dst))

def packet_to_flow_match(parent, packet):
    match = oftest.parse.packet_to_flow_match(packet)
    if ofp.OFP_VERSION in [1, 2]:
        match.wildcards |= required_wildcards(parent)
    else:
        # TODO remove incompatible OXM entries
        pass
    return match

def flow_msg_create(parent, pkt, ing_port=None, action_list=None, wildcards=None,
               egr_ports=None, egr_queue=None, check_expire=False, in_band=False):
    """
    Create a flow message

    Match on packet with given wildcards.  
    See flow_match_test for other parameter descriptoins
    @param egr_queue if not None, make the output an enqueue action
    @param in_band if True, do not wildcard ingress port
    @param egr_ports None (drop), single port or list of ports
    """
    match = oftest.parse.packet_to_flow_match(pkt)
    parent.assertTrue(match is not None, "Flow match from pkt failed")
    if wildcards is None:
        wildcards = required_wildcards(parent)
    if in_band:
        wildcards &= ~ofp.OFPFW_IN_PORT
    match.wildcards = wildcards
    match.in_port = ing_port

    if type(egr_ports) == type([]):
        egr_port_list = egr_ports
    else:
        egr_port_list = [egr_ports]

    request = ofp.message.flow_add()
    request.match = match
    request.buffer_id = 0xffffffff
    if check_expire:
        request.flags |= ofp.OFPFF_SEND_FLOW_REM
        request.hard_timeout = 1

    if ofp.OFP_VERSION == 1:
        actions = request.actions
    else:
        actions = []
        request.instructions.append(ofp.instruction.apply_actions(actions))

    if action_list is not None:
        actions.extend(action_list)

    # Set up output/enqueue action if directed
    if egr_queue is not None:
        parent.assertTrue(egr_ports is not None, "Egress port not set")
        act = ofp.action.enqueue()
        for egr_port in egr_port_list:
            act.port = egr_port
            act.queue_id = egr_queue
            actions.append(act)
    elif egr_ports is not None:
        for egr_port in egr_port_list:
            act = ofp.action.output()
            act.port = egr_port
            actions.append(act)

    logging.debug(request.show())

    return request

def flow_msg_install(parent, request, clear_table_override=None):
    """
    Install a flow mod message in the switch

    @param parent Must implement controller, assertEqual, assertTrue
    @param request The request, all set to go
    @param clear_table If true, clear the flow table before installing
    """

    clear_table = test_param_get('clear_table', default=True)
    if(clear_table_override != None):
        clear_table = clear_table_override

    if clear_table: 
        logging.debug("Clear flow table")
        delete_all_flows(parent.controller)

    logging.debug("Insert flow")
    parent.controller.message_send(request)

    do_barrier(parent.controller)

def flow_match_test_port_pair(parent, ing_port, egr_ports, wildcards=None,
                              vlan_vid=-1, pkt=None, exp_pkt=None,
                              action_list=None):
    """
    Flow match test on single TCP packet
    @param egr_ports A single port or list of ports

    Run test with packet through switch from ing_port to egr_port
    See flow_match_test for parameter descriptions
    """

    if wildcards is None:
        wildcards = required_wildcards(parent)
    logging.info("Pkt match test: " + str(ing_port) + " to " + 
                       str(egr_ports))
    logging.debug("  WC: " + hex(wildcards) + " vlan: " + str(vlan_vid))
    if pkt is None:
        pkt = simple_tcp_packet(dl_vlan_enable=(vlan_vid >= 0), vlan_vid=vlan_vid)
    if exp_pkt is None:
        exp_pkt = pkt

    request = flow_msg_create(parent, pkt, ing_port=ing_port, 
                              wildcards=wildcards, egr_ports=egr_ports,
                              action_list=action_list)

    flow_msg_install(parent, request)

    logging.debug("Send packet: " + str(ing_port) + " to " + 
                        str(egr_ports))
    parent.dataplane.send(ing_port, str(pkt))

    exp_ports = [ing_port if port == ofp.OFPP_IN_PORT else port for port in egr_ports]
    verify_packets(parent, exp_pkt, exp_ports)

def flow_match_test_pktout(parent, ing_port, egr_ports,
                           vlan_vid=-1, pkt=None, exp_pkt=None,
                           action_list=None):
    """
    Packet-out test on single TCP packet
    @param egr_ports A single port or list of ports

    Run test sending packet-out to egr_ports. The goal is to test the actions
    taken on the packet, not the matching which is of course irrelevant.
    See flow_match_test for parameter descriptions
    """

    if pkt is None:
        pkt = simple_tcp_packet(dl_vlan_enable=(vlan_vid >= 0), vlan_vid=vlan_vid)
    if exp_pkt is None:
        exp_pkt = pkt

    msg = ofp.message.packet_out()
    msg.in_port = ing_port
    msg.buffer_id = 0xffffffff
    msg.data = str(pkt)
    if action_list is not None:
        for act in action_list:
            msg.actions.append(act)

    # Set up output action
    if egr_ports is not None:
        for egr_port in egr_ports:
            act = ofp.action.output()
            act.port = egr_port
            msg.actions.append(act)

    logging.debug(msg.show())
    parent.controller.message_send(msg)

    exp_ports = [ing_port if port == ofp.OFPP_IN_PORT else port for port in egr_ports]
    verify_packets(parent, exp_pkt, exp_ports)

def get_egr_list(parent, of_ports, how_many, exclude_list=[]):
    """
    Generate a list of ports avoiding those in the exclude list
    @param parent Supplies logging
    @param of_ports List of OF port numbers
    @param how_many Number of ports to be added to the list
    @param exclude_list List of ports not to be used
    @returns An empty list if unable to find enough ports
    """

    if how_many == 0:
        return []

    count = 0
    egr_ports = []
    for egr_idx in range(len(of_ports)): 
        if of_ports[egr_idx] not in exclude_list:
            egr_ports.append(of_ports[egr_idx])
            count += 1
            if count >= how_many:
                return egr_ports
    logging.debug("Could not generate enough egress ports for test")
    return []
    
def flow_match_test(parent, port_map, wildcards=None, vlan_vid=-1, pkt=None, 
                    exp_pkt=None, action_list=None,
                    max_test=0, egr_count=1, ing_port=False):
    """
    Run flow_match_test_port_pair on all port pairs and packet-out

    @param max_test If > 0 no more than this number of tests are executed.
    @param parent Must implement controller, dataplane, assertTrue, assertEqual
    and logging
    @param pkt If not None, use this packet for ingress
    @param wildcards For flow match entry
    @param vlan_vid If not -1, and pkt is None, create a pkt w/ VLAN tag
    @param exp_pkt If not None, use this as the expected output pkt; els use pkt
    @param action_list Additional actions to add to flow mod
    @param egr_count Number of egress ports; -1 means get from config w/ dflt 2
    """
    if wildcards is None:
        wildcards = required_wildcards(parent)
    of_ports = port_map.keys()
    of_ports.sort()
    parent.assertTrue(len(of_ports) > 1, "Not enough ports for test")
    test_count = 0

    if egr_count == -1:
        egr_count = test_param_get('egr_count', default=2)
    
    for ing_idx in range(len(of_ports)):
        ingress_port = of_ports[ing_idx]
        egr_ports = get_egr_list(parent, of_ports, egr_count, 
                                 exclude_list=[ingress_port])
        if ing_port:
            egr_ports.append(ofp.OFPP_IN_PORT)
        if len(egr_ports) == 0:
            parent.assertTrue(0, "Failed to generate egress port list")

        flow_match_test_port_pair(parent, ingress_port, egr_ports, 
                                  wildcards=wildcards, vlan_vid=vlan_vid, 
                                  pkt=pkt, exp_pkt=exp_pkt,
                                  action_list=action_list)
        test_count += 1
        if (max_test > 0) and (test_count > max_test):
            logging.info("Ran " + str(test_count) + " tests; exiting")
            break

    if not test_param_get('pktout_actions', default=True):
        return

    ingress_port = of_ports[0]
    egr_ports = get_egr_list(parent, of_ports, egr_count,
                             exclude_list=[ingress_port])
    if ing_port:
        egr_ports.append(ofp.OFPP_IN_PORT)
    flow_match_test_pktout(parent, ingress_port, egr_ports,
                           vlan_vid=vlan_vid,
                           pkt=pkt, exp_pkt=exp_pkt,
                           action_list=action_list)

def test_param_get(key, default=None):
    """
    Return value passed via test-params if present

    @param key The lookup key
    @param default Default value to use if not found

    If the pair 'key=val' appeared in the string passed to --test-params
    on the command line, return val (as interpreted by exec).  Otherwise
    return default value.

    WARNING: TEST PARAMETERS MUST BE PYTHON IDENTIFIERS; 
    eg egr_count, not egr-count.
    """
    try:
        exec oftest.config["test_params"]
    except:
        return default

    try:
        return eval(str(key))
    except:
        return default

def action_generate(parent, field_to_mod, mod_field_vals):
    """
    Create an action to modify the field indicated in field_to_mod

    @param parent Must implement, assertTrue
    @param field_to_mod The field to modify as a string name
    @param mod_field_vals Hash of values to use for modified values
    """

    act = None

    if field_to_mod in ['pktlen']:
        return None

    if field_to_mod == 'eth_dst':
        act = ofp.action.set_dl_dst()
        act.dl_addr = oftest.parse.parse_mac(mod_field_vals['eth_dst'])
    elif field_to_mod == 'eth_src':
        act = ofp.action.set_dl_src()
        act.dl_addr = oftest.parse.parse_mac(mod_field_vals['eth_src'])
    elif field_to_mod == 'dl_vlan_enable':
        if not mod_field_vals['dl_vlan_enable']: # Strip VLAN tag
            act = ofp.action.strip_vlan()
        # Add VLAN tag is handled by vlan_vid field
        # Will return None in this case
    elif field_to_mod == 'vlan_vid':
        act = ofp.action.set_vlan_vid()
        act.vlan_vid = mod_field_vals['vlan_vid']
    elif field_to_mod == 'vlan_pcp':
        act = ofp.action.set_vlan_pcp()
        act.vlan_pcp = mod_field_vals['vlan_pcp']
    elif field_to_mod == 'ip_src':
        act = ofp.action.set_nw_src()
        act.nw_addr = oftest.parse.parse_ip(mod_field_vals['ip_src'])
    elif field_to_mod == 'ip_dst':
        act = ofp.action.set_nw_dst()
        act.nw_addr = oftest.parse.parse_ip(mod_field_vals['ip_dst'])
    elif field_to_mod == 'ip_tos':
        act = ofp.action.set_nw_tos()
        act.nw_tos = mod_field_vals['ip_tos']
    elif field_to_mod == 'tcp_sport':
        act = ofp.action.set_tp_src()
        act.tp_port = mod_field_vals['tcp_sport']
    elif field_to_mod == 'tcp_dport':
        act = ofp.action.set_tp_dst()
        act.tp_port = mod_field_vals['tcp_dport']
    elif field_to_mod == 'udp_sport':
        act = ofp.action.set_tp_src()
        act.tp_port = mod_field_vals['udp_sport']
    elif field_to_mod == 'udp_dport':
        act = ofp.action.set_tp_dst()
        act.tp_port = mod_field_vals['udp_dport']
    else:
        parent.assertTrue(0, "Unknown field to modify: " + str(field_to_mod))

    return act

def pkt_action_setup(parent, start_field_vals={}, mod_field_vals={}, 
                     mod_fields=[], tp="tcp", check_test_params=False):
    """
    Set up the ingress and expected packet and action list for a test

    @param parent Must implement assertTrue
    @param start_field_values Field values to use for ingress packet (optional)
    @param mod_field_values Field values to use for modified packet (optional)
    @param mod_fields The list of fields to be modified by the switch in the test.
    @params check_test_params If True, will check the parameters vid, add_vlan
    and strip_vlan from the command line.

    Returns a triple:  pkt-to-send, expected-pkt, action-list
    """

    new_actions = []

    base_pkt_params = {}
    base_pkt_params['pktlen'] = 100
    base_pkt_params['eth_dst'] = '00:DE:F0:12:34:56'
    base_pkt_params['eth_src'] = '00:23:45:67:89:AB'
    base_pkt_params['dl_vlan_enable'] = False
    base_pkt_params['vlan_vid'] = 2
    base_pkt_params['vlan_pcp'] = 0
    base_pkt_params['ip_src'] = '192.168.0.1'
    base_pkt_params['ip_dst'] = '192.168.0.2'
    base_pkt_params['ip_tos'] = 0
    if tp == "tcp":
        base_pkt_params['tcp_sport'] = 1234
        base_pkt_params['tcp_dport'] = 80
    elif tp == "udp":
        base_pkt_params['udp_sport'] = 1234
        base_pkt_params['udp_dport'] = 80
    for keyname in start_field_vals.keys():
        base_pkt_params[keyname] = start_field_vals[keyname]

    mod_pkt_params = {}
    mod_pkt_params['pktlen'] = 100
    mod_pkt_params['eth_dst'] = '00:21:0F:ED:CB:A9'
    mod_pkt_params['eth_src'] = '00:ED:CB:A9:87:65'
    mod_pkt_params['dl_vlan_enable'] = False
    mod_pkt_params['vlan_vid'] = 3
    mod_pkt_params['vlan_pcp'] = 7
    mod_pkt_params['ip_src'] = '10.20.30.40'
    mod_pkt_params['ip_dst'] = '50.60.70.80'
    mod_pkt_params['ip_tos'] = 0xf0
    if tp == "tcp":
        mod_pkt_params['tcp_sport'] = 4321
        mod_pkt_params['tcp_dport'] = 8765
    elif tp == "udp":
        mod_pkt_params['udp_sport'] = 4321
        mod_pkt_params['udp_dport'] = 8765
    for keyname in mod_field_vals.keys():
        mod_pkt_params[keyname] = mod_field_vals[keyname]

    # Check for test param modifications
    strip = False
    if check_test_params:
        add_vlan = test_param_get('add_vlan')
        strip_vlan = test_param_get('strip_vlan')
        vid = test_param_get('vid')

        if add_vlan and strip_vlan:
            parent.assertTrue(0, "Add and strip VLAN both specified")

        if vid:
            base_pkt_params['dl_vlan_enable'] = True
            base_pkt_params['vlan_vid'] = vid
            if 'vlan_vid' in mod_fields:
                mod_pkt_params['vlan_vid'] = vid + 1

        if add_vlan:
            base_pkt_params['dl_vlan_enable'] = False
            mod_pkt_params['dl_vlan_enable'] = True
            mod_pkt_params['pktlen'] = base_pkt_params['pktlen'] + 4
            mod_fields.append('pktlen')
            mod_fields.append('dl_vlan_enable')
            if 'vlan_vid' not in mod_fields:
                mod_fields.append('vlan_vid')
        elif strip_vlan:
            base_pkt_params['dl_vlan_enable'] = True
            mod_pkt_params['dl_vlan_enable'] = False
            mod_pkt_params['pktlen'] = base_pkt_params['pktlen'] - 4
            mod_fields.append('dl_vlan_enable')
            mod_fields.append('pktlen')

    if tp == "tcp":
        packet_builder = simple_tcp_packet
    elif tp == "udp":
        packet_builder = simple_udp_packet
    else:
        raise NotImplementedError("unknown transport protocol %s" % tp)

    # Build the ingress packet
    ingress_pkt = packet_builder(**base_pkt_params)

    # Build the expected packet, modifying the indicated fields
    for item in mod_fields:
        base_pkt_params[item] = mod_pkt_params[item]
        act = action_generate(parent, item, mod_pkt_params)
        if act:
            new_actions.append(act)

    expected_pkt = packet_builder(**base_pkt_params)

    return (ingress_pkt, expected_pkt, new_actions)

# Generate a simple "drop" flow mod
# If in_band is true, then only drop from first test port
def flow_mod_gen(port_map, in_band):
    request = ofp.message.flow_add()
    request.match.wildcards = ofp.OFPFW_ALL
    if in_band:
        request.match.wildcards = ofp.OFPFW_ALL - ofp.OFPFW_IN_PORT
        for of_port, ifname in port_map.items(): # Grab first port
            break
        request.match.in_port = of_port
    request.buffer_id = 0xffffffff
    return request

def skip_message_emit(parent, s):
    """
    Print out a 'skipped' message to stderr

    @param s The string to print out to the log file
    """
    global skipped_test_count

    skipped_test_count += 1
    logging.info("Skipping: " + s)
    if oftest.config["debug"] < logging.WARNING:
        sys.stderr.write("(skipped) ")
    else:
        sys.stderr.write("(S)")


def all_stats_get(parent):
    """
    Get the aggregate stats for all flows in the table
    @param parent Test instance with controller connection and assert
    @returns dict with keys flows, packets, bytes, active (flows), 
    lookups, matched
    """
    stat_req = ofp.message.aggregate_stats_request()
    stat_req.match = ofp.match()
    stat_req.match.wildcards = ofp.OFPFW_ALL
    stat_req.table_id = 0xff
    stat_req.out_port = ofp.OFPP_NONE

    rv = {}

    (reply, pkt) = parent.controller.transact(stat_req)
    parent.assertTrue(len(reply.entries) == 1, "Did not receive flow stats reply")

    for obj in reply.entries:
        (rv["flows"], rv["packets"], rv["bytes"]) = (obj.flow_count, 
                                                  obj.packet_count, obj.byte_count)
        break

    request = ofp.message.table_stats_request()
    (reply , pkt) = parent.controller.transact(request)

    
    (rv["active"], rv["lookups"], rv["matched"]) = (0,0,0)
    for obj in reply.entries:
        rv["active"] += obj.active_count
        rv["lookups"] += obj.lookup_count
        rv["matched"] += obj.matched_count

    return rv

_import_blacklist.add('FILTER')
FILTER=''.join([(len(repr(chr(x)))==3) and chr(x) or '.' 
                for x in range(256)])

def hex_dump_buffer(src, length=16):
    """
    Convert src to a hex dump string and return the string
    @param src The source buffer
    @param length The number of bytes shown in each line
    @returns A string showing the hex dump
    """
    result = ["\n"]
    for i in xrange(0, len(src), length):
       chars = src[i:i+length]
       hex = ' '.join(["%02x" % ord(x) for x in chars])
       printable = ''.join(["%s" % ((ord(x) <= 127 and
                                     FILTER[ord(x)]) or '.') for x in chars])
       result.append("%04x  %-*s  %s\n" % (i, length*3, hex, printable))
    return ''.join(result)

def format_packet(pkt):
    return "Packet length %d \n%s" % (len(str(pkt)), 
                                      hex_dump_buffer(str(pkt)))

def inspect_packet(pkt):
    """
    Wrapper around scapy's show() method.
    @returns A string showing the dissected packet.
    """
    from cStringIO import StringIO
    out = None
    backup = sys.stdout
    try:
        tmp = StringIO()
        sys.stdout = tmp
        pkt.show2()
        out = tmp.getvalue()
        tmp.close()
    finally:
        sys.stdout = backup
    return out

def nonstandard(cls):
    """
    Testcase decorator that marks the test as being non-standard.
    These tests are not automatically added to the "standard" group.
    """
    cls._nonstandard = True
    return cls

def disabled(cls):
    """
    Testcase decorator that marks the test as being disabled.
    These tests are not automatically added to the "standard" group or
    their module's group.
    """
    cls._disabled = True
    return cls

def group(name):
    """
    Testcase decorator that adds the test to a group.
    """
    def fn(cls):
        if not hasattr(cls, "_groups"):
            cls._groups = []
        cls._groups.append(name)
        return cls
    return fn

def version(ver):
    """
    Testcase decorator that specifies which versions of OpenFlow the test
    supports. The default is 1.0+. This decorator may only be used once.

    Supported syntax:
    1.0 -> 1.0
    1.0,1.2,1.3 -> 1.0, 1.2, 1.3
    1.0+ -> 1.0, 1.1, 1.2, 1.3
    """
    versions = parse_version(ver)
    def fn(cls):
        cls._versions = versions
        return cls
    return fn

def parse_version(ver):
    allowed_versions = ["1.0", "1.1", "1.2", "1.3"]
    if re.match("^1\.\d+$", ver):
        versions = set([ver])
    elif re.match("^(1\.\d+)\+$", ver):
        if not ver[:-1] in allowed_versions:
            raise ValueError("invalid OpenFlow version %s" % ver[:-1])
        versions = set()
        if ver != "1.1+": versions.add("1.0")
        if ver != "1.2+": versions.add("1.1")
        if ver != "1.3+": versions.add("1.2")
        versions.add("1.3")
    else:
        versions = set(ver.split(','))

    for version in versions:
        if not version in allowed_versions:
            raise ValueError("invalid OpenFlow version %s" % version)

    return versions

assert(parse_version("1.0") == set(["1.0"]))
assert(parse_version("1.0,1.2,1.3") == set(["1.0", "1.2", "1.3"]))
assert(parse_version("1.0+") == set(["1.0", "1.1", "1.2", "1.3"]))

def get_stats(test, req):
    """
    Retrieve a list of stats entries. Handles OFPSF_REPLY_MORE.
    """
    msgtype = ofp.OFPT_STATS_REPLY
    more_flag = ofp.OFPSF_REPLY_MORE
    stats = []
    reply, _ = test.controller.transact(req)
    test.assertTrue(reply is not None, "No response to stats request")
    test.assertEquals(reply.type, msgtype, "Response had unexpected message type")
    stats.extend(reply.entries)
    while reply.flags & more_flag != 0:
        reply, pkt = test.controller.poll(exp_msg=msgtype)
        test.assertTrue(reply is not None, "No response to stats request")
        stats.extend(reply.entries)
    return stats

def get_flow_stats(test, match, table_id=None,
                   out_port=None, out_group=None,
                   cookie=0, cookie_mask=0):
    """
    Retrieve a list of flow stats entries.
    """

    if table_id == None:
        if ofp.OFP_VERSION <= 2:
            table_id = 0xff
        else:
            table_id = ofp.OFPTT_ALL

    if out_port == None:
        if ofp.OFP_VERSION == 1:
            out_port = ofp.OFPP_NONE
        else:
            out_port = ofp.OFPP_ANY

    if out_group == None:
        if ofp.OFP_VERSION > 1:
            out_group = ofp.OFPP_ANY

    req = ofp.message.flow_stats_request(match=match,
                                         table_id=table_id,
                                         out_port=out_port)
    if ofp.OFP_VERSION > 1:
        req.out_group = out_group
        req.cookie = cookie
        req.cookie_mask = cookie_mask

    return get_stats(test, req)

def get_port_stats(test, port_no):
    """
    Retrieve a list of port stats entries.
    """
    req = ofp.message.port_stats_request(port_no=port_no)
    return get_stats(test, req)

def get_queue_stats(test, port_no, queue_id):
    """
    Retrieve a list of queue stats entries.
    """
    req = ofp.message.queue_stats_request(port_no=port_no, queue_id=queue_id)
    return get_stats(test, req)

def verify_flow_stats(test, match, table_id=0xff,
                      initial=[],
                      pkts=None, bytes=None):
    """
    Verify that flow stats changed as expected.

    Optionally takes an 'initial' list of stats entries, as returned by
    get_flow_stats(). If 'initial' is not given the counters are assumed to
    begin at 0.
    """

    def accumulate(stats):
        pkts_acc = bytes_acc = 0
        for stat in stats:
            pkts_acc += stat.packet_count
            bytes_acc += stat.byte_count
        return (pkts_acc, bytes_acc)

    pkts_before, bytes_before = accumulate(initial)

    # Wait 10s for counters to update
    pkt_diff = byte_diff = None
    for i in range(0, 100):
        stats = get_flow_stats(test, match, table_id=table_id)
        pkts_after, bytes_after = accumulate(stats)
        pkt_diff = pkts_after - pkts_before
        byte_diff = bytes_after - bytes_before
        if (pkts == None or pkt_diff >= pkts) and \
           (bytes == None or byte_diff >= bytes):
            break
        time.sleep(0.1)

    if pkts != None:
        test.assertEquals(pkt_diff, pkts, "Flow packet counter not updated properly (expected increase of %d, got increase of %d)" % (pkts, pkt_diff))

    if bytes != None:
        test.assertTrue(byte_diff >= bytes and byte_diff <= bytes*1.1,
                        "Flow byte counter not updated properly (expected increase of %d, got increase of %d)" % (bytes, byte_diff))

def verify_port_stats(test, port,
                      initial=[],
                      tx_pkts=None, rx_pkts=None,
                      tx_bytes=None, rx_bytes=None):
    """
    Verify that port stats changed as expected.

    Optionally takes an 'initial' list of stats entries, as returned by
    get_port_stats(). If 'initial' is not given the counters are assumed to
    begin at 0.
    """
    def accumulate(stats):
        tx_pkts_acc = rx_pkts_acc = tx_bytes_acc = rx_bytes_acc = 0
        for stat in stats:
            tx_pkts_acc += stat.tx_packets
            rx_pkts_acc += stat.rx_packets
            tx_bytes_acc += stat.tx_bytes
            rx_bytes_acc += stat.rx_bytes
        return (tx_pkts_acc, rx_pkts_acc, tx_bytes_acc, rx_bytes_acc)

    tx_pkts_before, rx_pkts_before, \
        tx_bytes_before, rx_bytes_before = accumulate(initial)

    # Wait 10s for counters to update
    for i in range(0, 100):
        stats = get_port_stats(test, port)
        tx_pkts_after, rx_pkts_after, \
            tx_bytes_after, rx_bytes_after = accumulate(stats)
        tx_pkts_diff = tx_pkts_after - tx_pkts_before
        rx_pkts_diff = rx_pkts_after - rx_pkts_before
        tx_bytes_diff = tx_bytes_after - tx_bytes_before
        rx_bytes_diff = rx_bytes_after - rx_bytes_before
        if (tx_pkts == None or tx_pkts <= tx_pkts_diff) and \
           (rx_pkts == None or rx_pkts <= rx_pkts_diff) and \
           (tx_bytes == None or tx_bytes <= tx_bytes_diff) and \
           (rx_bytes == None or rx_bytes <= rx_bytes_diff):
            break
        time.sleep(0.1)

    if (tx_pkts != None):
        test.assertGreaterEqual(tx_pkts_diff, tx_pkts,
            "Port TX packet counter is not updated correctly (expected increase of %d, got increase of %d)" % (tx_pkts, tx_pkts_diff))
    if (rx_pkts != None):
        test.assertGreaterEqual(rx_pkts_diff, rx_pkts,
            "Port RX packet counter is not updated correctly (expected increase of %d, got increase of %d)" % (rx_pkts, rx_pkts_diff))
    if (tx_bytes != None):
        test.assertGreaterEqual(tx_bytes_diff, tx_bytes,
            "Port TX byte counter is not updated correctly (expected increase of %d, got increase of %d)" % (tx_bytes, tx_bytes_diff))
    if (rx_bytes != None):
        test.assertGreaterEqual(rx_bytes_diff, rx_bytes,
            "Port RX byte counter is not updated correctly (expected increase of %d, got increase of %d)" % (rx_bytes, rx_bytes_diff))

def verify_queue_stats(test, port_no, queue_id,
                       initial=[],
                       pkts=None, bytes=None):
    """
    Verify that queue stats changed as expected.

    Optionally takes an 'initial' list of stats entries, as returned by
    get_queue_stats(). If 'initial' is not given the counters are assumed to
    begin at 0.
    """
    def accumulate(stats):
        pkts_acc = bytes_acc = 0
        for stat in stats:
            pkts_acc += stat.tx_packets
            bytes_acc += stat.tx_bytes
        return (pkts_acc, bytes_acc)

    pkts_before, bytes_before = accumulate(initial)

    # Wait 10s for counters to update
    pkt_diff = byte_diff = None
    for i in range(0, 100):
        stats = get_queue_stats(test, port_no, queue_id)
        pkts_after, bytes_after = accumulate(stats)
        pkt_diff = pkts_after - pkts_before
        byte_diff = bytes_after - bytes_before
        if (pkts == None or pkt_diff >= pkts) and \
           (bytes == None or byte_diff >= bytes):
            break
        time.sleep(0.1)

    if pkts != None:
        test.assertEquals(pkt_diff, pkts, "Queue packet counter not updated properly (expected increase of %d, got increase of %d)" % (pkts, pkt_diff))

    if bytes != None:
        test.assertTrue(byte_diff >= bytes and byte_diff <= bytes*1.1,
                        "Queue byte counter not updated properly (expected increase of %d, got increase of %d)" % (bytes, byte_diff))

def packet_in_match(msg, data, in_port=None, reason=None):
    """
    Check whether the packet_in message 'msg' has fields matching 'data',
    'in_port', and 'reason'.

    This function handles truncated packet_in data. The 'in_port' and 'reason'
    parameters are optional.

    @param msg packet_in message
    @param data Expected packet_in data
    @param in_port Expected packet_in in_port, or None
    @param reason Expected packet_in reason, or None
    """

    if ofp.OFP_VERSION <= 2:
        pkt_in_port = msg.in_port
    else:
        oxms = { type(oxm): oxm for oxm in msg.match.oxm_list }
        if ofp.oxm.in_port in oxms:
            pkt_in_port = oxms[ofp.oxm.in_port].value
        else:
            logging.warn("Missing in_port in packet-in message")
            pkt_in_port = None

    if in_port != None and in_port != pkt_in_port:
        logging.debug("Incorrect packet_in in_port (expected %d, received %d)", in_port, pkt_in_port)
        return False

    if reason != None and reason != msg.reason:
        logging.debug("Incorrect packet_in reason (expected %d, received %d)", reason, msg.reason)
        return False

    # Check that one of the packets is a prefix of the other.
    # The received packet may be either truncated or padded, but not both.
    # (Some of the padding may be truncated but that's irrelevant). We
    # need to check that the smaller packet is a prefix of the larger one.
    # Note that this check succeeds if the switch sends a zero-length
    # packet-in.
    compare_len = min(len(msg.data), len(data))
    if data[:compare_len] != msg.data[:compare_len]:
        logging.debug("Incorrect packet_in data")
        logging.debug("Expected %s" % format_packet(data[:compare_len]))
        logging.debug("Received %s" % format_packet(msg.data[:compare_len]))
        return False

    return True

def verify_packet_in(test, data, in_port, reason, controller=None):
    """
    Assert that the controller receives a packet_in message matching data 'data'
    from port 'in_port' with reason 'reason'. Does not trigger the packet_in
    itself, that's up to the test case.

    @param test Instance of base_tests.SimpleProtocol
    @param pkt String to expect as the packet_in data
    @param in_port OpenFlow port number to expect as the packet_in in_port
    @param reason One of OFPR_* to expect as the packet_in reason
    @param controller Controller instance, defaults to test.controller
    @returns The received packet-in message
    """

    if controller == None:
        controller = test.controller

    end_time = time.time() + oftest.ofutils.default_timeout

    while True:
        msg, _ = controller.poll(ofp.OFPT_PACKET_IN, end_time - time.time())
        if not msg:
            # Timeout
            break
        elif packet_in_match(msg, data, in_port, reason):
            # Found a matching message
            break

    test.assertTrue(msg is not None, 'Packet in message not received on port %r' % in_port)
    return msg

def verify_no_packet_in(test, data, in_port, controller=None):
    """
    Assert that the controller does not receive a packet_in message matching
    data 'data' from port 'in_port'.

    @param test Instance of base_tests.SimpleProtocol
    @param pkt String to expect as the packet_in data
    @param in_port OpenFlow port number to expect as the packet_in in_port
    @param controller Controller instance, defaults to test.controller
    """

    if controller == None:
        controller = test.controller

    # Negative test, need to wait a short amount of time before checking we
    # didn't receive the message.
    time.sleep(oftest.ofutils.default_negative_timeout)

    # Check every packet_in queued in the controller
    while True:
        msg, _ = controller.poll(ofp.OFPT_PACKET_IN, timeout=0)
        if msg == None:
            # No more queued packet_in messages
            break
        elif packet_in_match(msg, data, in_port, None):
            # Found a matching message
            break

    if in_port == None:
        test.assertTrue(msg == None, "Did not expect a packet-in message on any port")
    else:
        test.assertTrue(msg == None, "Did not expect a packet-in message on port %d" % in_port)

def openflow_ports(num=None):
    """
    Return a list of 'num' OpenFlow port numbers

    If 'num' is None, return all available ports. Otherwise, limit the length
    of the result to 'num' and raise an exception if not enough ports are
    available.
    """
    ports = sorted(oftest.config["port_map"].keys())
    if num != None and len(ports) < num:
        raise Exception("test requires %d ports but only %d are available" % (num, len(ports)))
    return ports[:num]

def verify_packet(test, pkt, ofport):
    """
    Check that an expected packet is received
    """
    logging.debug("Checking for pkt on port %r", ofport)
    (rcv_port, rcv_pkt, pkt_time) = test.dataplane.poll(port_number=ofport, exp_pkt=str(pkt))
    test.assertTrue(rcv_pkt != None, "Did not receive pkt on %r" % ofport)
    return (rcv_port, rcv_pkt, pkt_time)
    
def verify_no_packet(test, pkt, ofport):
    """
    Check that a particular packet is not received
    """
    logging.debug("Negative check for pkt on port %r", ofport)
    (rcv_port, rcv_pkt, pkt_time) = \
        test.dataplane.poll(
            port_number=ofport, exp_pkt=str(pkt),
            timeout=oftest.ofutils.default_negative_timeout)
    test.assertTrue(rcv_pkt == None, "Received packet on %r" % ofport)

def verify_no_other_packets(test):
    """
    Check that no unexpected packets are received

    This is a no-op if the --relax option is in effect.
    """
    if oftest.config["relax"]:
        return
    logging.debug("Checking for unexpected packets on all ports")
    (rcv_port, rcv_pkt, pkt_time) = test.dataplane.poll(timeout=oftest.ofutils.default_negative_timeout)
    if rcv_pkt != None:
        logging.debug("Received unexpected packet on port %r: %s", rcv_port, format_packet(rcv_pkt))
    test.assertTrue(rcv_pkt == None, "Unexpected packet on port %r" % rcv_port)

def verify_packets(test, pkt, ofports):
    """
    Check that a packet is received on certain ports

    Also verifies that the packet is not received on any other ports, and that no
    other packets are received (unless --relax is in effect).

    This covers the common and simplest cases for checking dataplane outputs.
    For more complex usage, like multiple different packets being output, or
    multiple packets on the same port, use the primitive verify_packet,
    verify_no_packet, and verify_no_other_packets functions directly.
    """
    pkt = str(pkt)
    for ofport in openflow_ports():
        if ofport in ofports:
            verify_packet(test, pkt, ofport)
        else:
            verify_no_packet(test, pkt, ofport)
    verify_no_other_packets(test)

def verify_no_errors(ctrl):
    error, _ = ctrl.poll(ofp.OFPT_ERROR, 0)
    if error:
        raise AssertionError("unexpected error type=%d code=%d" % (error.err_type, error.code))

def verify_capability(test, capability):
    """
    Return True if DUT supports the specified capability.

    @param test Instance of base_tests.SimpleProtocol
    @param capability One of ofp_capabilities.
    """
    logging.info("Verifing that capability code is valid.")
    test.assertIn(capability, ofp.const.ofp_capabilities_map,
                  "Capability code %d does not exist." % capability)
    capability_str = ofp.const.ofp_capabilities_map[capability]
    
    logging.info(("Sending features_request to test if capability "
                  "%s is supported."), capability_str)
    req = ofp.message.features_request()
    res, raw = test.controller.transact(req)
    test.assertIsNotNone(res, "Did not receive a response from the DUT.")
    test.assertEqual(res.type, ofp.OFPT_FEATURES_REPLY,
                     ("Unexpected packet type %d received in response to "
                      "OFPT_FEATURES_REQUEST") % res.type)
    logging.info("Received features_reply.")
    
    if (res.capabilities & capability) > 0:
        logging.info("Switch capabilities bitmask claims to support %s",
                     capability_str)
        return True, res.capabilities
    else:
        logging.info("Capabilities bitmask does not support %s.",
                     capability_str)
        return False, res.capabilities

def verify_configuration_flag(test, flag):
    """
    Return True if DUT supports specified configuration flag.

    @param test Instance of base_tests.SimpleProtocol
    @param flag One of ofp_config_flags.
    @returns (supported, flags) Bool if flag is set and flag values.
    """
    logging.info("Verifing that flag is valid.")
    test.assertIn(flag, ofp.const.ofp_config_flags_map,
                  "flag  %s does not exist." % flag)
    flag_str = ofp.const.ofp_config_flags_map[flag]

    logging.info("Sending OFPT_GET_CONFIG_REQUEST.")    
    req = ofp.message.get_config_request()
    rv = test.controller.message_send(req)
    test.assertNotEqual(rv, -1, "Not able to send get_config_request.")

    logging.info("Expecting OFPT_GET_CONFIG_REPLY ")
    (res, pkt) = test.controller.poll(exp_msg=ofp.OFPT_GET_CONFIG_REPLY,
                                      timeout=2)
    test.assertIsNotNone(res, "Did not receive OFPT_GET_CONFIG_REPLY")
    logging.info("Received OFPT_GET_CONFIG_REPLY ")

    if res.flags == flag:
        logging.info("%s flag is set.", flag_str)
        return True, res.flags
    else:
        logging.info("%s flag is not set.", flag_str)
        return False, res.flags

__all__ = list(set(locals()) - _import_blacklist)