It's the identification field of the IPv4 header. Mostly this is used to match
up fragments (which should all retain the same value). So time.time() isn't
really a very good value for it anyway, as it should be relatively unique, but
int(time.time()) is only unique for packets sent in different seconds which
seems like a fairly unsafe assumption. We should probably just use a counter.
Which, looking at the code... it looks like may have been done in the past
(ip_id field) and then changed. It should probably be changed back. :) I
think that's what I did when I fixed it before; it must just have not made it
out of some experimental branch. Sorry it got you!
-- Murphy
On Aug 8, 2011, at 3:18 PM, Aaron Rosen wrote:
> Thanks that did the trick.
>
> Yea I thought this was strange too since this used to work a while ago.
>
> Out of curiosity what is id in ipv4.py I see that it holds the time but why
> is that needed?
>
> Thanks again,
>
> Aaron
>
> On Mon, Aug 8, 2011 at 6:13 PM, Murphy McCauley <jam...@nau.edu> wrote:
> Strange, I am positive that I have fixed this. Maybe it just hasn't gotten
> pushed yet.
>
> In ipv4.py around line 76, try something like...
> self.id = int(time.time()) & 0xffff
>
> -- Murphy
>
> On Aug 8, 2011, at 3:08 PM, Aaron Rosen wrote:
>
>> Thanks,
>>
>> I hate to bug you again but this looks fine to me?
>>
>> iplen = 39 len("hello world")(11) + udp header(8) + 20 (ip_header)
>> 17 = UDP_PROTOCOL
>>
>> bad packet [69, 0, 39, 1312840938, 0, 64, 17, 0, 167837954, 167837953]
>> 00019|pyrt|ERR:unable to invoke a Python event handler:
>> Traceback (most recent call last):
>> File "./nox/lib/util.py", line 114, in f
>> event.total_len, buffer_id, packet)
>> File "./nox/coreapps/examples/sos.py", line 644, in packet_in_callback
>> learn(dpid, inport, packet, packet.arr, bufid)
>> File "./nox/coreapps/examples/sos.py", line 212, in learn
>> forward(dpid, inport, packet, packet.arr, bufid, TRUNK_PORT)
>> File "./nox/coreapps/examples/sos.py", line 333, in forward
>> ret = install_agent_flows(dpid, inport, packet, buf, bufid, TRUNK_PORT);
>> File "./nox/coreapps/examples/sos.py", line 594, in install_agent_flows
>> inst.send_openflow_packet(dp_near, inform_dest.tostring(),
>> inst.Agents[dp_near]['inport'], inport)
>> File "./nox/lib/packet/packet_base.py", line 118, in tostring
>> return ''.join((buf, self.next.tostring()))
>> File "./nox/lib/packet/packet_base.py", line 113, in tostring
>> buf = self.hdr()
>> File "./nox/lib/packet/ipv4.py", line 179, in hdr
>> self.dstip)
>> error: 'H' format requires 0 <= number <= 65535
>>
>>
>> On Mon, Aug 8, 2011 at 5:32 PM, Murphy McCauley <jam...@nau.edu> wrote:
>> I think you just have a field with a bad value.
>>
>> Try replacing the checksum function with something like this to help you
>> spot it:
>>
>> def checksum(self):
>> try:
>> data = struct.pack('!BBHHBBHII', (self.v << 4) + self.hl, self.tos,
>> self.iplen, self.id,
>> (self.flags << 13) | self.frag, self.ttl,
>> self.protocol, 0, self.srcip,
>> self.dstip)
>> return checksum(data, 0)
>> except:
>> print "bad packet",[(self.v << 4) + self.hl,
>> self.tos,
>> self.iplen, self.id,
>> (self.flags << 13) | self.frag, self.ttl,
>> self.protocol, 0, self.srcip,
>> self.dstip]
>>
>> -- Murphy
>>
>> On Aug 8, 2011, at 1:50 PM, Aaron Rosen wrote:
>>
>>> Hello,
>>>
>>> I emailed the mailing list about this before but it seems like maybe
>>> something changed or maybe I'm blind. Anyways, the following code generates
>>> the following execption. Any ideas what's going wrong?
>>>
>>>
>>> def send_udp(mac, dstip, srcip, port, payload):
>>> l4 = udp()
>>> l4.srcport = 1999
>>> l4.dstport = 1998
>>> l4.len = udp.MIN_LEN + len("hello world")
>>> l4.set_payload("hello world")
>>> l4.arr = l4.tostring()
>>>
>>> l3 = ipv4()
>>> l3.iplen = ipv4.MIN_LEN + l4.len
>>> l3.protocol = ipv4.UDP_PROTOCOL
>>> l3.dstip = ipstr_to_int("10.1.1.1")
>>> l3.srcip = ipstr_to_int("10.1.1.2")
>>> l3.set_payload(l4)
>>>
>>> l2 = ethernet()
>>> l2.set_payload(l3)
>>> l2.dst = octstr_to_array("00:00:00:00:00:01")
>>> l2.src = octstr_to_array("00:00:00:00:00:09")
>>> l2.type = ethernet.IP_TYPE
>>> l3.checksum()
>>> l4.csum = l4.checksum()
>>> return l2
>>>
>>>
>>> 00019|pyrt|ERR:unable to invoke a Python event handler:
>>> Traceback (most recent call last):
>>> File "./nox/lib/util.py", line 114, in f
>>> event.total_len, buffer_id, packet)
>>> File "./nox/coreapps/examples/sos.py", line 626, in packet_in_callback
>>> learn(dpid, inport, packet, packet.arr, bufid)
>>> File "./nox/coreapps/examples/sos.py", line 194, in learn
>>> forward(dpid, inport, packet, packet.arr, bufid, TRUNK_PORT)
>>> File "./nox/coreapps/examples/sos.py", line 315, in forward
>>> ret = install_agent_flows(dpid, inport, packet, buf, bufid, TRUNK_PORT);
>>> File "./nox/coreapps/examples/sos.py", line 575, in install_agent_flows
>>> inform_dest = send_udp(mac, dstip, srcip, port, payload)
>>> File "./nox/coreapps/examples/sos.py", line 89, in send_udp
>>> l3.checksum()
>>> File "./nox/lib/packet/ipv4.py", line 162, in checksum
>>> self.dstip)
>>> error: 'H' format requires 0 <= number <= 65535
>>>
>>>
>>> On Mon, Jun 20, 2011 at 1:59 PM, Aaron Rosen <aro...@clemson.edu> wrote:
>>> Thanks Murphy!
>>>
>>> You're right, that did the trick.
>>>
>>> Aaron
>>>
>>> On Mon, Jun 20, 2011 at 1:55 PM, Murphy McCauley <jam...@nau.edu> wrote:
>>> > So I think the call to l3.checksum() is extraneous, but the real issue is
>>> > probably that l3.iplen should be ipv4.MIN_LEN + l4.len.
>>> >
>>> > -- Murphy
>>> >
>>> > On Monday, June 20, 2011 09:42:07 AM Aaron Rosen wrote:
>>> >> Hi Murphy,
>>> >>
>>> >> wow... Opps...
>>> >>
>>> >> I'm trying the following: This doesn't return any errors but in
>>> >> wireshark the packet_outs say Malformed UDP packets.
>>> >>
>>> >> def send_udp_message():
>>> >>
>>> >> l4 = udp()
>>> >> l4.srcport = 1999
>>> >> l4.dstport = 1888
>>> >> l4.len = udp.MIN_LEN + len("hello_world")
>>> >> l4.set_payload("Hello_world")
>>> >> l4.arr = l4.tostring()
>>> >>
>>> >> l3 = ipv4()
>>> >> l3.iplen = ipv4.MIN_LEN
>>> >> l3.protocol = ipv4.UDP_PROTOCOL
>>> >> l3.dstip = ipstr_to_int("130.127.39.7");
>>> >> l3.srcip = ipstr_to_int("1.1.1.1");
>>> >> l3.set_payload(l4)
>>> >>
>>> >> l2 = ethernet()
>>> >> l2.set_payload(l3)
>>> >> l2.dst = octstr_to_array("00:00:00:00:00:02")
>>> >> l2.dst = octstr_to_array("a1:00:04:00:0a:04")
>>> >> l2.type = ethernet.IP_TYPE
>>> >> l3.checksum()
>>> >> l4.csum = l4.checksum()
>>> >>
>>> >> return l2
>>> >>
>>> >> ....
>>> >> inst.send_openflow_packet(dpid, send_udp_message().tostring(),
>>> >> openflow.OFPP_FLOOD, inport)
>>> >> source = mac_to_str(packet.src)
>>> >>
>>> >> On Mon, Jun 20, 2011 at 12:29 PM, Murphy McCauley <jam...@nau.edu> wrote:
>>> >> > Unfortunately, your tweak breaks the logic of the assert.
>>> >> >
>>> >> > The assert is asserting that self.next is a packet_base of some sort
>>> >> > OR a
>>> >> > string. You've set it to a string, so... it should be a string. So it
>>> >> > should definitely not be a packet_base. So the first of your asserts
>>> >> > will always fail.
>>> >> >
>>> >> > For the sake of testing, would you please comment out the first of your
>>> >> > two asserts (leaving only the one against type('')), and let me know
>>> >> > the
>>> >> > result?
>>> >> >
>>> >> > -- Murphy
>>> >> >
>>> >> > On Monday, June 20, 2011 09:22:23 AM Aaron Rosen wrote:
>>> >> >> Hi Murphy,
>>> >> >>
>>> >> >> I'm using zaku but the one in destiny looked the same to be.
>>> >> >>
>>> >> >> I changed to assert to be on two lines so I could see which one was
>>> >> >> firing.
>>> >> >>
>>> >> >> def checksum(self):
>>> >> >> #assert(isinstance(self.next, packet_base) or type(self.next)
>>> >> >> == type(''))
>>> >> >> assert(isinstance(self.next, packet_base))
>>> >> >> assert(type(self.next) == type(''))
>>> >> >>
>>> >> >>
>>> >> >> Thanks,
>>> >> >>
>>> >> >> Aaron
>>> >> >>
>>> >> >> On Mon, Jun 20, 2011 at 12:19 PM, Murphy McCauley <jam...@nau.edu>
>>> >> >> wrote:
>>> >> >> > What NOX are you using? Your udp.py does not seem to be the one in
>>> >> >> > zaku or destiny...
>>> >> >> >
>>> >> >> > -- Murphy
>>> >> >> >
>>> >> >> > On Sunday, June 19, 2011 03:34:20 PM Aaron Rosen wrote:
>>> >> >> >> Hello,
>>> >> >> >>
>>> >> >> >> I'm trying to send udp packets from my controller but I'm getting
>>> >> >> >> the
>>> >> >> >> following assertion when I call udp().checksum(). I was hoping
>>> >> >> >> someone could point out where I'm going wrong.
>>> >> >> >>
>>> >> >> >> Thanks,
>>> >> >> >>
>>> >> >> >> Aaron
>>> >> >> >>
>>> >> >> >> Traceback (most recent call last):
>>> >> >> >> File "./nox/lib/util.py", line 116, in f
>>> >> >> >> event.total_len, buffer_id, packet)
>>> >> >> >> File "./nox/coreapps/examples/sos.py", line 299, in
>>> >> >> >> packet_in_callback learn(dpid, inport, packet)
>>> >> >> >> File "./nox/coreapps/examples/sos.py", line 56, in learn
>>> >> >> >> send_packet = send_udp_message()
>>> >> >> >> File "./nox/coreapps/examples/sos.py", line 48, in
>>> >> >> >> send_udp_message
>>> >> >> >> l4.csum = l4.checksum()
>>> >> >> >> File "./nox/lib/packet/udp.py", line 111, in checksum
>>> >> >> >> assert(isinstance(self.next, packet_base))
>>> >> >> >> AssertionError
>>> >> >> >>
>>> >> >> >>
>>> >> >> >> def send_udp_message():
>>> >> >> >>
>>> >> >> >> l4 = udp()
>>> >> >> >> l4.srcport = 1999
>>> >> >> >> l4.dstport = 1888
>>> >> >> >> l4.len = udp.MIN_LEN + len("hello_world")
>>> >> >> >> l4.set_payload("Hello_world")
>>> >> >> >>
>>> >> >> >> l3 = ipv4()
>>> >> >> >> l3.iplen = ipv4.MIN_LEN
>>> >> >> >> l3.protocol = ipv4.UDP_PROTOCOL
>>> >> >> >> l3.dstip = ipstr_to_int("130.127.39.7");
>>> >> >> >> l3.srcip = ipstr_to_int("1.1.1.1");
>>> >> >> >> l3.set_payload(l4)
>>> >> >> >>
>>> >> >> >> l2 = ethernet()
>>> >> >> >> l2.set_payload(l3)
>>> >> >> >> l2.dst = octstr_to_array("00:00:00:00:00:02")
>>> >> >> >> l2.dst = octstr_to_array("a1:00:04:00:0a:04")
>>> >> >> >> l2.type = ethernet.IP_TYPE
>>> >> >> >> l3.checksum()
>>> >> >> >> l4.csum = l4.checksum()
>>> >> >> >>
>>> >> >> >> return l2
>>> >> >> >>
>>> >> >> >>
>>> >> >> >> ....
>>> >> >> >> send_packet = send_udp_message()
>>> >> >> >> inst.send_openflow_packet(dpid, send_packet.tostring(),
>>> >> >> >> openflow.OFPP_FLOOD, inport)
>>> >
>>>
>>>
>>>
>>> --
>>> Aaron O. Rosen
>>> Masters Student - Network Communication
>>> 306B Fluor Daniel
>>>
>>>
>>>
>>> --
>>> Aaron O. Rosen
>>> Masters Student - Network Communication
>>> 306B Fluor Daniel
>>>
>>>
>>
>>
>>
>>
>> --
>> Aaron O. Rosen
>> Masters Student - Network Communication
>> 306B Fluor Daniel
>>
>>
>
>
>
>
> --
> Aaron O. Rosen
> Masters Student - Network Communication
> 306B Fluor Daniel
>
>
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