Configuration

Configure the HDDS dissector via Wireshark preferences.

Preferences

Access preferences at: Edit → Preferences → Protocols → HDDS

Preference	Default	Description
Types JSON	(empty)	Path to types JSON file for CDR decoding
Decode CDR	true	Enable/disable CDR payload decoding
Show Raw Hex	false	Display raw hex alongside decoded data
Verbose	false	Show additional debug info in info column

CDR Type Decoding

To enable full payload decoding, provide a types JSON file describing your data types.

Generate Types File

# Future: hdds_gen will generate this
hdds_gen --wireshark your_types.idl -o types.ws.json

Manual Types File

Create a JSON file with your types:

{
  "types": {
    "Temperature": {
      "kind": "struct",
      "fields": [
        { "name": "sensor_id", "type": "string" },
        { "name": "value", "type": "float64" },
        { "name": "unit", "type": "string" }
      ]
    },
    "SensorReading": {
      "kind": "struct",
      "fields": [
        { "name": "timestamp", "type": "uint64" },
        { "name": "sensor_type", "type": "uint8" },
        { "name": "readings", "type": "float32[]" }
      ]
    }
  },
  "topics": {
    "sensors/temperature": {
      "type": "Temperature"
    },
    "sensors/readings": {
      "type": "SensorReading"
    }
  }
}

Supported Types

Type	CDR Size	Description
uint8	1 byte	Unsigned 8-bit integer
int8	1 byte	Signed 8-bit integer
uint16	2 bytes	Unsigned 16-bit integer
int16	2 bytes	Signed 16-bit integer
uint32	4 bytes	Unsigned 32-bit integer
int32	4 bytes	Signed 32-bit integer
uint64	8 bytes	Unsigned 64-bit integer
int64	8 bytes	Signed 64-bit integer
float32	4 bytes	IEEE 754 single precision
float64	8 bytes	IEEE 754 double precision
string	4 + len + padding	CDR string (length-prefixed)
bytes	4 + len + padding	Raw byte sequence

Set Types Path

1. Edit → Preferences → Protocols → HDDS
2. Set Types JSON to your file path (e.g., /home/user/dds_types.json)
3. Click OK
4. Reload dissector: Analyze → Reload Lua Plugins (or restart Wireshark)

Vendor IDs

The dissector recognizes these vendor IDs:

ID	Vendor Name
0x0000	UNKNOWN
0x0101	RTI Connext
0x0102	OpenSplice (ADLink)
0x0103	OpenDDS (OCI)
0x010F	FastDDS (eProsima)
0x0110	Cyclone DDS
0x0112	RustDDS
0x01AA	HDDS

HDDS packets (0x01AA) are automatically highlighted with [HDDS] prefix.

Entity IDs

Well-known entity IDs are decoded by name:

ID	Name	Purpose
0x000001C1	PARTICIPANT	Participant entity
0x000100C2	SPDP_WRITER	Participant discovery writer
0x000100C7	SPDP_READER	Participant discovery reader
0x000003C2	SEDP_PUB_WRITER	Publication discovery writer
0x000003C7	SEDP_PUB_READER	Publication discovery reader
0x000004C2	SEDP_SUB_WRITER	Subscription discovery writer
0x000004C7	SEDP_SUB_READER	Subscription discovery reader
0x000300C3	TYPELOOKUP_REQ	Type lookup request
0x000300C4	TYPELOOKUP_REP	Type lookup reply

Troubleshooting

Dissector Not Loading

Check the Lua console for errors:

1. Tools → Lua → Console
2. Look for [HDDS] messages
3. Should show: [HDDS] RTPS Dissector loaded - Version 1.0.0

No HDDS Tree in Packets

• Verify packets are on ports 7400-7500
• Check packets have valid RTPS magic (RTPS)
• Enable the protocol: Analyze → Enabled Protocols → hdds

CDR Decoding Not Working

• Verify types JSON file path is correct and readable
• Check Lua console for JSON parsing errors
• Ensure JSON format matches expected schema
• Reload Lua plugins after changing preferences

Reload Without Restart

To apply changes without restarting Wireshark:

Analyze → Reload Lua Plugins

Or use the keyboard shortcut (Ctrl+Shift+L) to open Lua evaluation.

Debug Output

Enable Verbose preference to add debug info to the info column.

For more detailed debugging, add print statements to the Lua file:

print("[HDDS] Debug: " .. message)

Output appears in Tools → Lua → Console.