[pox-dev] Errors when sending new created packets

[Weiyang Mo]

Hi,All

I plan to send a packet from the controller out the port whenever I
receiver packet_in on that port. That's what I already did in NOX.

here's my following code:
def _handle_PacketIn (event):
          udp_packet = udp()
           payload = "123456890"
          udp_packet.srcport = 11118
          udp_packet.dstport = 18888
          udp_packet.len = udp.MIN_LEN + len(payload)
          udp_packet.set_payload(payload)
          ipv4_packet = ipv4()
          ipv4_packet.iplen = ipv4.MIN_LEN + udp_packet.len
          ipv4_packet.protocol = ipv4.UDP_PROTOCOL
          ipv4_packet.dstip = "10.0.0.4"
          ipv4_packet.srcip = "192.168.1.101"
          ipv4_packet.set_payload(udp_packet)
          eth_packet = ethernet()
          eth_packet.set_payload(ipv4_packet)
          eth_packet.src = EthAddr("00:00:00:00:00:11")
          eth_packet.dst = EthAddr("00:00:00:00:00:22")
          eth_packet.type = ethernet.IP_TYPE
#          udp_packet.csum = udp_packet.checksum()
          msg = of.ofp_packet_out(data = eth_packet)
          msg.actions.append(of.ofp_action_output(port = event.port))
          log.debug ("the configuration command is successully sent")

However I get the following errors:
 msg = of.ofp_packet_out(data = eth_packet)
  File "/home/openflow/pox/pox/openflow/libopenflow_01.py", line 2905, in
__init__
    initHelper(self, kw)
  File "/home/openflow/pox/pox/lib/util.py", line 220, in initHelper
    setattr(obj, k, v)
  File "/home/openflow/pox/pox/openflow/libopenflow_01.py", line 2916, in
_set_data
    self._data = data.pack()
  File "/home/openflow/pox/pox/lib/packet/packet_base.py", line 168, in pack
    rest = self.next.pack()
  File "/home/openflow/pox/pox/lib/packet/packet_base.py", line 168, in pack
    rest = self.next.pack()
  File "/home/openflow/pox/pox/lib/packet/packet_base.py", line 172, in pack
    return self.hdr(rest) + rest
  File "/home/openflow/pox/pox/lib/packet/udp.py", line 108, in hdr
    self.csum = self.checksum()
  File "/home/openflow/pox/pox/lib/packet/udp.py", line 135, in checksum
    ippacket = struct.pack('!IIBBH', self.prev.srcip.toUnsigned(),
AttributeError: 'str' object has no attribute 'toUnsigned'


Any advice?

Thanks very much.

Weiyang
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