dtn7-go

Delay-Tolerant Networking software suite and library based on the Bundle Protocol Version 7.

Protocols

This software implements the current draft of the Bundle Protocol Version 7.

• Bundle Protocol Version 7 (RFC 9171)

Convergence Layer

A convergence layer in bundle protocol parlance is the abstraction for peer-to-peer communication. We have implemented the following protocols:

• Minimal TCP Convergence-Layer Protocol (mtcp) (draft-ietf-dtn-mtcpcl-01)
• Delay-Tolerant Networking TCP Convergence-Layer Protocol Version 4 (tcpcl) (RFC 9174), including:
  • WebSocket-based variant
• Bundle Broadcasting Connector, a generic Broadcasting Interface
  • rf95modem based CLA for LoRa PHY by rf95modem-go

At this point, mtcp is probably your best bet for reliable data transfer.

Routing

We have implemented the following routing algorithms:

• Epidemic Routing
• Spray and Wait, vanilla and binary
• Delay-Tolerant Link State Routing (DTLSR)
• Probabilistic Routing Protocol using History of Encounters and Transitivity (PRoPHET)
• Sensor Network-specific routing algorithm for Data Mules, documentation

Software

Installation

Package Manager

• Arch Linux: dtn7 (AUR)
• macOS: jonashoechst/hoechst/dtn7 (brew)
• Nix / NixOS: dtn7/nur-packages (NUR)

From Source

Install the Go programming language, version 1.16 or later.

git clone https://github.com/dtn7/dtn7-go.git
cd dtn7-go

go build ./cmd/dtn-tool
go build ./cmd/dtnd

dtnd

dtnd is a delay-tolerant networking daemon. It acts as a node in the network and can transmit, receive and forward bundles to other nodes. A node's neighbours may be specified in the configuration or detected within the local network through a peer discovery. Bundles might be sent and received through a REST-like web interface. The features and configuration are described inside the provided example configuration.toml.

REST API / WebSocket API

We provide different interfaces to allow communication from external programs with dtnd. More precisely: a REST API and a WebSocket API.

The simpler REST API allows a client to register itself with an address, receive bundles and create/dispatch new ones simply by POSTing JSON objects to dtnd's RESTful HTTP server. The endpoints and structure of the JSON objects are described in the documentation for the github.com/dtn7/dtn7-go/agent.RestAgent type.

If you need bidirectional communication, you can use the WebSocket API. This API sends CBOR-encoded messages. For details, see the ws_agent-files of the agent package. But one can also simply use it with the github.com/dtn7/dtn7-go/agent.WebSocketAgentConnector, which implements a client.

dtn-tool

dtn-tool is a swiss army knife for bundles and uses the WebSockets API.

It allows the simple creation of new bundles, written to a file or the stdout. Furthermore, one can print out bundles as a human/machine-readable JSON object. To exchange bundles, dtn-tool may watch a directory and send all new bundle files to the corresponding dtnd instance. In the same way, incoming bundles from dtnd are stored in this directory.

Usage of ./dtn-tool create|exchange|ping|show:

./dtn-tool create sender receiver -|filename [-|filename]
  Creates a new Bundle, addressed from sender to receiver with the stdin (-)
  or the given file (filename) as payload. If no further specified, the
  Bundle is stored locally named after the hex representation of its ID.
  Otherwise, the Bundle can be written to the stdout (-) or saved
  according to a freely selectable filename.

./dtn-tool exchange websocket endpoint-id directory
  ./dtn-tool registeres itself as an agent on the given websocket and writes
  incoming Bundles in the directory. If the user dropps a new Bundle in the
  directory, it will be sent to the server.

./dtn-tool ping websocket sender receiver
  Send continuously bundles from sender to receiver over a websocket.

./dtn-tool show -|filename
  Prints a JSON version of a Bundle, read from stdin (-) or filename.

Go Library

Most components of this software are usable as a Go library. Those libraries are available within the pkg-directory.

For example, the bpv7-package contains code for bundle modification, serialization and deserialization and would most likely be the most interesting part. If you are interested in working with this code, check out the documentation.

Contributing

We warmly welcome any contribution.

Please format your code using Gofmt. Further inspection of the code via golangci-lint is highly recommended, our CI-pipeline includes a golangci-lint-action.

As a development environment, you may, of course, use whatever you personally like best. However, we have had a good experience with GoLand, especially because of the size of the project.

Assuming you have a supported version of the Go programming language installed, just clone the repository and install the dependencies as documented in the Installation, From Source section above.

Please document your changes in your commit messages and the CHANGELOG.md file.

Also, we attempt to be REUSE compliant. You can use the contrib/reuse/reuse-headers.py-script for automatic copyright header generation.

OS-specific

macOS

Installing the Go programming language via brew, should solve permission errors while trying to fetch the dependencies.

License

This project's code is licensed under the GNU General Public License version 3 (GPL-3.0-or-later). We use the REUSE-tool to simplify the copyright stuff.