fix: resolve final addon review

tests/test_runtime.sh

@@ -209,26 +209,34 @@ assert_processes_return_to_baseline() {
 
 assert_loopback_cdp_listener() {
     local container="$1"
-    local artifact="$2"
-    docker exec "$container" cat /proc/net/tcp > "$artifact"
+    local tcp_artifact="$2"
+    local tcp6_artifact="$3"
+    docker exec "$container" cat /proc/net/tcp > "$tcp_artifact"
+    docker exec "$container" cat /proc/net/tcp6 > "$tcp6_artifact"
     docker exec -i "$container" python3 - <<'PY'
 expected = f"0100007F:{9222:04X}"
-wildcard = f"00000000:{9222:04X}"
 if expected != "0100007F:2406":
     raise SystemExit(f"unexpected 9222 hexadecimal encoding: {expected}")
 
-listeners = set()
-with open("/proc/net/tcp", encoding="ascii") as handle:
-    next(handle)
-    for line in handle:
-        fields = line.split()
-        if len(fields) >= 4 and fields[3] == "0A":
-            listeners.add(fields[1].upper())
+listeners = {"/proc/net/tcp": set(), "/proc/net/tcp6": set()}
+for table in ("/proc/net/tcp", "/proc/net/tcp6"):
+    with open(table, encoding="ascii") as handle:
+        next(handle)
+        for line in handle:
+            fields = line.split()
+            if len(fields) < 4 or fields[3] != "0A":
+                continue
+            local_address = fields[1].upper()
+            if local_address.rsplit(":", 1)[-1] != "2406":
+                continue
+            listeners[table].add(local_address)
+            if table == "/proc/net/tcp6":
+                raise SystemExit(f"IPv6 CDP listener present: {local_address}")
 
-if expected not in listeners:
-    raise SystemExit(f"missing loopback CDP listener {expected}: {sorted(listeners)}")
-if wildcard in listeners:
-    raise SystemExit(f"wildcard CDP listener present: {wildcard}")
+if listeners["/proc/net/tcp"] != {expected}:
+    raise SystemExit(
+        f"IPv4 CDP listeners = {sorted(listeners['/proc/net/tcp'])}, want [{expected}]"
+    )
 PY
 }
 
@@ -370,7 +378,10 @@ first_port="$(host_port "$first_container")"
 wait_ready "$first_container" "$first_port"
 first_baseline="$(capture_process_baseline "$first_container")"
 assert_no_9222_mapping "$first_container"
-assert_loopback_cdp_listener "$first_container" "${artifacts_dir}/runtime-proc-net-tcp.txt"
+assert_loopback_cdp_listener \
+    "$first_container" \
+    "${artifacts_dir}/runtime-proc-net-tcp.txt" \
+    "${artifacts_dir}/runtime-proc-net-tcp6.txt"
 probe_and_close_cdp "$first_container"
 assert_processes_return_to_baseline "$first_container" "$first_baseline"
 post_invalid_worker "$first_port" "${artifacts_dir}/runtime-invalid-worker-response.json"
@@ -383,7 +394,10 @@ second_port="$(host_port "$second_container")"
 wait_ready "$second_container" "$second_port"
 second_baseline="$(capture_process_baseline "$second_container")"
 assert_no_9222_mapping "$second_container"
-assert_loopback_cdp_listener "$second_container" "${artifacts_dir}/runtime-restart-proc-net-tcp.txt"
+assert_loopback_cdp_listener \
+    "$second_container" \
+    "${artifacts_dir}/runtime-restart-proc-net-tcp.txt" \
+    "${artifacts_dir}/runtime-restart-proc-net-tcp6.txt"
 probe_and_close_cdp "$second_container"
 assert_processes_return_to_baseline "$second_container" "$second_baseline"