fix(bug): wrong max string len constant

examples/ubuntu/main.cpp

@@ -40,6 +40,7 @@ IntegerDesc_t __attribute__((weak)) integer_desc_pool[] = {
 IntegerParamValue_t integer_values_pool[sizeof(integer_desc_pool) / sizeof(IntegerDesc_t)];
 
 StringDesc_t __attribute__((weak)) string_desc_pool[] = {
+    {"uavcan.node.description", "", true},
     {"system.name", "dronecan_application", true},
 };
 StringParamValue_t string_values_pool[sizeof(string_desc_pool) / sizeof(StringDesc_t)];
@@ -140,7 +141,7 @@ void lights_callback(const uavcan_equipment_indication_LightsCommand &msg)
 int main()
 {
 
-    paramsInit(1, 1, -1, 1);
+    paramsInit(1, 2, -1, 1);
     paramsResetToDefault();
     ParamsApi params_api = {
         .getName = paramsGetName,

include/libdcnode/legacy/uavcan/protocol/param/getset.h

@@ -88,7 +88,7 @@ uint16_t uavcanParamGetSetMakeStringResponse(
 
     // Value value (uint8[<=128] string_value)
     canardEncodeScalar(buffer, 5, 3, &tag_string);
-    uint8_t string_size = strlenSafely(str_val, 128);
+    uint8_t string_size = strlenSafely(str_val, STRING_MAX_SIZE);
     uint16_t string_bit_offset = string_size * 8;
     canardEncodeScalar(buffer, 8, 8, &string_size);
     memcpy(&buffer[2], str_val, string_size);

tests/smoke_socketcan.py

@@ -1,20 +1,55 @@
 #!/usr/bin/env python3
+import time
 from pathlib import Path
 import dronecan
 import pytest
 
+pytestmark = pytest.mark.filterwarnings(
+    "ignore:The 'bustype' argument is deprecated.*:DeprecationWarning"
+)
+
 APP_NODE_ID = 50
 APP_IFACE = "slcan0"
 NODE_ID_TESTER = 100
 MESSAGE_TIMEOUT = 1.2
-SERVICE_TIMEOUT = 0.2
+SERVICE_TIMEOUT = 1.0
+MAX_STRING_LENGTH = 56
+PARAM_DESCRIPTION_INDEX = 1
+PARAM_SYSTEM_NAME_INDEX = 2
+PARAM_DESCRIPTION_NAME = "uavcan.node.description"
+PARAM_SYSTEM_NAME = "system.name"
 
 def make_dronecan_node() -> dronecan.node.Node:
-    node = dronecan.make_node(APP_IFACE, node_id=NODE_ID_TESTER, bitrate=1_000_000, baudrate=1_000_000)
+    node = dronecan.make_node(
+        APP_IFACE,
+        node_id=NODE_ID_TESTER,
+        bitrate=1_000_000,
+        baudrate=1_000_000,
+        node_status_interval=3600,
+    )
     node.mode = dronecan.uavcan.protocol.NodeStatus().MODE_OPERATIONAL
     node.health = dronecan.uavcan.protocol.NodeStatus().HEALTH_OK
     return node
 
+def request(node: dronecan.node.Node, payload):
+    response_transfer_event = None
+
+    def _callback(transfer_event: dronecan.node.TransferEvent):
+        nonlocal response_transfer_event
+        if transfer_event is None or transfer_event.transfer.source_node_id != APP_NODE_ID:
+            return
+        response_transfer_event = transfer_event
+
+    node.request(payload, APP_NODE_ID, _callback, timeout=SERVICE_TIMEOUT)
+    deadline = time.monotonic() + SERVICE_TIMEOUT + 0.1
+    while response_transfer_event is None and time.monotonic() < deadline:
+        node.spin(0.01)
+    assert response_transfer_event is not None, f"{payload} response is missing"
+    return response_transfer_event.response
+
+def as_string(value) -> str:
+    return str(value).rstrip("\x00")
+
 @pytest.mark.dependency()
 def test_node_status():
     node = make_dronecan_node()
@@ -59,5 +94,34 @@ def _get_info_callback(transfer_event: dronecan.node.TransferEvent):
     assert get_node_info_response_transfer_event.transfer.dest_node_id == NODE_ID_TESTER
     assert get_node_info_response_transfer_event.response.name.decode("utf-8").rstrip("\x00") == "com.example.libdcnode.sitl"
 
+@pytest.mark.dependency(depends=["test_node_status"])
+def test_max_length_string_param():
+    node = make_dronecan_node()
+    max_string = "S" * MAX_STRING_LENGTH
+    neighbor_marker = "AFTER_MAX_STRING"
+
+    req = dronecan.uavcan.protocol.param.GetSet.Request(name=PARAM_SYSTEM_NAME)
+    req.value = dronecan.uavcan.protocol.param.Value(string_value=neighbor_marker)
+    response = request(node, req)
+    assert as_string(response.name) == PARAM_SYSTEM_NAME
+    assert as_string(response.value.string_value) == neighbor_marker
+
+    req = dronecan.uavcan.protocol.param.GetSet.Request(name=PARAM_DESCRIPTION_NAME)
+    req.value = dronecan.uavcan.protocol.param.Value(string_value=max_string)
+    response = request(node, req)
+    assert as_string(response.name) == PARAM_DESCRIPTION_NAME
+    assert as_string(response.value.string_value) == max_string
+
+    req = dronecan.uavcan.protocol.param.GetSet.Request(index=PARAM_DESCRIPTION_INDEX)
+    response = request(node, req)
+    assert as_string(response.name) == PARAM_DESCRIPTION_NAME
+    assert as_string(response.value.string_value) == max_string
+    assert neighbor_marker not in as_string(response.value.string_value)
+
+    req = dronecan.uavcan.protocol.param.GetSet.Request(index=PARAM_SYSTEM_NAME_INDEX)
+    response = request(node, req)
+    assert as_string(response.name) == PARAM_SYSTEM_NAME
+    assert as_string(response.value.string_value) == neighbor_marker
+
 if __name__ == "__main__":
     raise SystemExit(pytest.main([str(Path(__file__).resolve())]))