DDS-XRCE Protocol dissector for Wireshark

This is a Wireshark dissector for the DDS for eXtremely Resource Constrained Environments (DDS-XRCE) protocol. In particular the Micro-XRCE-DDS implementation.

The dissector handles both UDP and TCP transports. To support the Micro-XRCE-DDS examples out of the box, it assumes that the agent and client communicate over port 2018, but this can be changed in the preferences.

Installation

To use the dissector, copy dds-xrce-idl.lua, dds-xrce-proto.lua and dds-xrce-types.lua to ~/.local/lib/wireshark/plugins and (re)start Wireshark.

Used-defined data types

The dissector is capable of deserializing user-defined data types, provided

• Wireshark captures the packets that create the DDS entities (topics, datareaders and datawriters),
• deserialization functions are registered for the data types,
• and only a single client is connected to the agent.

HelloWorld example

The HelloWorld examples in Micro-XRCE-DDS-Client all publish their messages on the HelloWorldTopic topic with the following data type:

struct HelloWorld {
  unsigned long index;
  string message;
};

To enable the dissector to deserialize these messages, create the ~/.local/lib/wireshark/plugins/HelloWorld.lua file, containing:

require "dds-xrce-idl"

local function HelloWorld_deserialize(tvb, offset, encoding, tree, label)
    local subtree = tree:add(tvb(offset), label)
    local subtree_begin = offset

    offset = unsigned_long_deserialize(tvb, offset, encoding, subtree, "index:")
    offset = string_deserialize(tvb, offset, encoding, subtree, "message:")

    subtree:set_len(offset - subtree_begin)

    return offset
end
types["HelloWorld"] = HelloWorld_deserialize

The examples create the DDS entities with a Qos XML string, in which case this is enough information.

If, instead, you create the entities with a reference to a profile in the QoS XML supplied to the agent, you need to provide some more information. First, associate the data type with a topic by adding the following line to HelloWorld.lua:

topic_type_names["HelloWorldTopic"] = "HelloWorld"

Second, associate the topic name with the profile references by adding the following three lines:

topic_names["my_topic_profile"] = "HelloWorldTopic"
data_reader_topic_names["my_data_reader_profile"] = "HelloWorldTopic"
data_writer_topic_names["my_data_writer_profile"] = "HelloWorldTopic"

Capturing the packets of the PublishHelloWorld example results in the following dissection: