[PATCH v6 3/7] dts: add optional packet filtering to scapy sniffer

[Jeremy Spewock]

On Mon, Jan 8, 2024 at 7:01 AM Juraj Linkeš <juraj.linkes at pantheon.tech>
wrote:

> On Wed, Jan 3, 2024 at 11:33 PM <jspewock at iol.unh.edu> wrote:
> >
> > From: Jeremy Spewock <jspewock at iol.unh.edu>
> >
> > Added the options to filter out LLDP and ARP packets when
> > sniffing for packets with scapy. This was done using BPF filters to
> > ensure that the noise these packets provide does not interfere with test
> > cases.
> >
> > Signed-off-by: Jeremy Spewock <jspewock at iol.unh.edu>
> > ---
> >  dts/framework/test_suite.py                   | 15 +++++++++--
> >  dts/framework/testbed_model/tg_node.py        | 14 ++++++++--
> >  .../traffic_generator/__init__.py             |  7 ++++-
> >  .../capturing_traffic_generator.py            | 22 ++++++++++++++-
> >  .../testbed_model/traffic_generator/scapy.py  | 27 +++++++++++++++++++
> >  5 files changed, 79 insertions(+), 6 deletions(-)
> >
>
> <snip>
>
> > diff --git
> a/dts/framework/testbed_model/traffic_generator/capturing_traffic_generator.py
> b/dts/framework/testbed_model/traffic_generator/capturing_traffic_generator.py
> > index 0246590333..c1c9facedd 100644
> > ---
> a/dts/framework/testbed_model/traffic_generator/capturing_traffic_generator.py
> > +++
> b/dts/framework/testbed_model/traffic_generator/capturing_traffic_generator.py
> <snip>
> > @@ -26,6 +27,19 @@ def _get_default_capture_name() -> str:
> >      return str(uuid.uuid4())
> >
> >
> > + at dataclass(slots=True)
>
> This should also be frozen. If we need a different filter, it's better
> to create a new object I think.
>
> > +class PacketFilteringConfig:
> > +    """The supported filtering options for
> :class:`CapturingTrafficGenerator`.
> > +
> > +    Attributes:
> > +        no_lldp: If :data:`True`, LLDP packets will be filtered out
> when capturing.
> > +        no_arp: If :data:`True`, ARP packets will be filtered out when
> capturing.
> > +    """
> > +
> > +    no_lldp: bool = True
> > +    no_arp: bool = True
> > +
> > +
> >  class CapturingTrafficGenerator(TrafficGenerator):
> >      """Capture packets after sending traffic.
> >
> <snip>
> > diff --git a/dts/framework/testbed_model/traffic_generator/scapy.py
> b/dts/framework/testbed_model/traffic_generator/scapy.py
> > index 5b60f66237..505de0be94 100644
> > --- a/dts/framework/testbed_model/traffic_generator/scapy.py
> > +++ b/dts/framework/testbed_model/traffic_generator/scapy.py
> <snip>
> > @@ -260,11 +263,34 @@ def _send_packets(self, packets: list[Packet],
> port: Port) -> None:
> >          packets = [packet.build() for packet in packets]
> >          self.rpc_server_proxy.scapy_send_packets(packets,
> port.logical_name)
> >
> > +    def _create_packet_filter(self, filter_config:
> PacketFilteringConfig) -> str:
> > +        """Combines filter settings from `filter_config` into a BPF
> that scapy can use.
> > +
> > +        Scapy allows for the use of Berkeley Packet Filters (BPFs) to
> filter what packets are
> > +        collected based on various attributes of the packet.
> > +
> > +        Args:
> > +            filter_config: Config class that specifies which filters
> should be applied.
> > +
> > +        Returns:
> > +            A string representing the combination of BPF filters to be
> passed to scapy. For
> > +            example:
> > +
> > +            "ether[12:2] != 0x88cc && ether[12:2] != 0x0806"
> > +        """
> > +        bpf_filter: list[str] = []
>
> The type hint here is not needed, so let's make this consistent with
> the rest of the code - we don't specify local type hints if they're
> not necessary.
>

Good catch, this might have been left over from when I was experimenting
with formatting the filters, I'll remove it.


>
> > +        if filter_config.no_arp:
> > +            bpf_filter.append("ether[12:2] != 0x0806")
> > +        if filter_config.no_lldp:
> > +            bpf_filter.append("ether[12:2] != 0x88cc")
> > +        return " && ".join(bpf_filter)
> > +
> >      def _send_packets_and_capture(
> >          self,
> >          packets: list[Packet],
> >          send_port: Port,
> >          receive_port: Port,
> > +        filter_config: PacketFilteringConfig,
> >          duration: float,
> >          capture_name: str = _get_default_capture_name(),
> >      ) -> list[Packet]:
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mails.dpdk.org/archives/dev/attachments/20240108/ad98ed5a/attachment.htm>