[PATCH v1] dts: only sniff inbound packets

[Patrick Robb <probb@iol.unh.edu>]

Add a filter to the Scapy traffic generator sniffer which
forces the sniffer to ignore outbound traffic, preventing
double counting of packets. Without this change sniffing
will double count packets when DTS is being run with a
single link topology, because the Scapy packet transmission
and Scapy sniffing is happening on the same port. The
correct behavior is to only count inbound traffic which is
being returned to the traffic generator by the DTS SUT.

Fixes: dfb667368077 ("dts: add Scapy asynchronous sniffer")

Signed-off-by: Patrick Robb <probb@iol.unh.edu>
---
 dts/framework/testbed_model/traffic_generator/scapy.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/dts/framework/testbed_model/traffic_generator/scapy.py b/dts/framework/testbed_model/traffic_generator/scapy.py
index 9e15a31c00..c6e9006205 100644
--- a/dts/framework/testbed_model/traffic_generator/scapy.py
+++ b/dts/framework/testbed_model/traffic_generator/scapy.py
@@ -203,7 +203,7 @@ def _sniff(self, recv_port: Port) -> None:
         ready_prompt = "Ready."
         self.send_command(
             "sniff("
-            f'iface="{recv_port.logical_name}", quiet=True, store=False, '
+            f'iface="{recv_port.logical_name}", filter="inbound", quiet=True, store=False, '
             "prn=lambda p: bytes_base64(p.build()).decode(), "
             f'started_callback=lambda: print("{ready_prompt}")'
             ")",
-- 
2.49.0