Add PTF test file for basic forwarding exercise

Author: aqn96

exercises/basic/ptf/basic_fwd.py

@@ -0,0 +1,147 @@
+#!/usr/bin/env python3
+
+# Copyright 2026 Andrew Nguyen
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import logging
+
+import ptf
+import ptf.testutils as tu
+from ptf.base_tests import BaseTest
+import p4runtime_sh.shell as sh
+import p4runtime_shell_utils as shu
+
+
+# Configure logging
+logger = logging.getLogger(None)
+ch = logging.StreamHandler()
+ch.setLevel(logging.INFO)
+formatter = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')
+ch.setFormatter(formatter)
+logger.addHandler(ch)
+
+
+class BasicFwdTest(BaseTest):
+    def setUp(self):
+        self.dataplane = ptf.dataplane_instance
+        self.dataplane.flush()
+
+        logging.debug("BasicFwdTest.setUp()")
+        grpc_addr = tu.test_param_get("grpcaddr")
+        if grpc_addr is None:
+            grpc_addr = 'localhost:9559'
+        p4info_txt_fname = tu.test_param_get("p4info")
+        p4prog_binary_fname = tu.test_param_get("config")
+        sh.setup(device_id=0,
+                 grpc_addr=grpc_addr,
+                 election_id=(0, 1),
+                 config=sh.FwdPipeConfig(p4info_txt_fname, p4prog_binary_fname),
+                 verbose=False)
+
+    def tearDown(self):
+        logging.debug("BasicFwdTest.tearDown()")
+        sh.teardown()
+
+
+######################################################################
+# Helper function to add entries to ipv4_lpm table
+######################################################################
+
+def add_ipv4_lpm_entry(ipv4_addr_str, prefix_len, dst_mac_str, port):
+    te = sh.TableEntry('MyIngress.ipv4_lpm')(action='MyIngress.ipv4_forward')
+    te.match['hdr.ipv4.dstAddr'] = '%s/%d' % (ipv4_addr_str, prefix_len)
+    te.action['dstAddr'] = dst_mac_str
+    te.action['port'] = '%d' % port
+    te.insert()
+
+
+class DropTest(BasicFwdTest):
+    """Test that packets are dropped when no table entries are installed."""
+    def runTest(self):
+        in_dmac = 'ee:30:ca:9d:1e:00'
+        in_smac = 'ee:cd:00:7e:70:00'
+        ip_dst = '10.0.1.1'
+        ig_port = 1
+
+        pkt = tu.simple_tcp_packet(eth_src=in_smac, eth_dst=in_dmac,
+                                   ip_dst=ip_dst, ip_ttl=64)
+        tu.send_packet(self, ig_port, pkt)
+        tu.verify_no_other_packets(self)
+
+
+class FwdTest(BasicFwdTest):
+    """Test that a packet is forwarded correctly with one table entry."""
+    def runTest(self):
+        in_dmac = 'ee:30:ca:9d:1e:00'
+        in_smac = 'ee:cd:00:7e:70:00'
+        ip_dst = '10.0.1.1'
+        ig_port = 1
+
+        eg_port = 2
+        out_dmac = '08:00:00:00:02:22'
+
+        # Add a forwarding entry
+        add_ipv4_lpm_entry(ip_dst, 32, out_dmac, eg_port)
+
+        # Send packet
+        pkt = tu.simple_tcp_packet(eth_src=in_smac, eth_dst=in_dmac,
+                                   ip_dst=ip_dst, ip_ttl=64)
+
+        # Expected: srcAddr = old dstAddr, dstAddr = new MAC, TTL decremented
+        exp_pkt = tu.simple_tcp_packet(eth_src=in_dmac, eth_dst=out_dmac,
+                                       ip_dst=ip_dst, ip_ttl=63)
+        tu.send_packet(self, ig_port, pkt)
+        tu.verify_packets(self, exp_pkt, [eg_port])
+
+
+class MultiEntryTest(BasicFwdTest):
+    """Test multiple LPM entries route to different ports correctly."""
+    def runTest(self):
+        in_dmac = 'ee:30:ca:9d:1e:00'
+        in_smac = 'ee:cd:00:7e:70:00'
+        ig_port = 0
+
+        entries = []
+        entries.append({'ip_dst': '10.0.1.1',
+                        'prefix_len': 32,
+                        'pkt_dst': '10.0.1.1',
+                        'eg_port': 1,
+                        'out_dmac': '08:00:00:00:01:11'})
+        entries.append({'ip_dst': '10.0.2.0',
+                        'prefix_len': 24,
+                        'pkt_dst': '10.0.2.99',
+                        'eg_port': 2,
+                        'out_dmac': '08:00:00:00:02:22'})
+        entries.append({'ip_dst': '10.0.3.0',
+                        'prefix_len': 24,
+                        'pkt_dst': '10.0.3.1',
+                        'eg_port': 3,
+                        'out_dmac': '08:00:00:00:03:33'})
+
+        # Add all entries
+        for e in entries:
+            add_ipv4_lpm_entry(e['ip_dst'], e['prefix_len'],
+                               e['out_dmac'], e['eg_port'])
+
+        # Test each entry
+        ttl_in = 64
+        for e in entries:
+            pkt = tu.simple_tcp_packet(eth_src=in_smac, eth_dst=in_dmac,
+                                       ip_dst=e['pkt_dst'], ip_ttl=ttl_in)
+            exp_pkt = tu.simple_tcp_packet(eth_src=in_dmac, eth_dst=e['out_dmac'],
+                                           ip_dst=e['pkt_dst'],
+                                           ip_ttl=ttl_in - 1)
+            tu.send_packet(self, ig_port, pkt)
+            tu.verify_packets(self, exp_pkt, [e['eg_port']])
+            ttl_in -= 10