v0.6.3

Date: 2026-10-21
Previous release: v0.6.2

Summary

Four behaviours of the command line and of the simulated outstation follow what the documentation promises: usage errors honour --format json, a binary built with go install reports its version, a connection style on the command line wins over another one in the environment, and over UDP the event log says connected once a master is known. Commands, flags and the JSON shapes are unchanged.

Changed

• Usage errors and --format json: an unknown command or flag, a missing required flag or a value a flag cannot hold is now the JSON error object {"error": {"kind": "usage", "code": "invalid_input", "message": ...}} on stdout when the invocation asks for JSON, by --format json (also --format=json, wherever it stands on the command line) or by DNP3CTL_OUTPUT_FORMAT=json for a command that has --format. It was always the text error: line on stderr. The exit code stays 2, and text stays as it was. server generate-config --format is the format of the model file it writes, not of a result, so its errors stay text.
• Connection styles, environment and command line: a flag of one connection style on the command line now wins over the environment variables of the others, as for every other flag: client … --ip works with DNP3CTL_URL set (likewise --url, --listen with DNP3CTL_IP, DNP3CTL_MASTER_LISTEN), and server start --dial with DNP3CTL_PORT or DNP3CTL_UDP set (likewise --serial, and --listen, --port, --udp, --udp-peer, --allow with DNP3CTL_DIAL or DNP3CTL_SERIAL). Two styles both on the command line, or both in the environment, are still refused as mutually exclusive.
• go-dnp3 v1.3.2, which runs its interop suite against otfabric/dnp3-interop v0.4.3 (the FAQ says so); no change of the library.
• Docs: README.md, docs/json-output.md, docs/exitcodes.md and docs/server-config.md describe the new behaviour, and say why server generate-config --format takes yaml or json.

Fixed

• Version of go install binaries: a binary built without the ldflags of the release (go install …@v0.6.3, go build) reported version dev. It now reports the version the go toolchain records, such as v0.6.3 (with go build in a clone the one it derives from the git tags, such as v0.6.3+dirty), and the git commit it records, when there is one; dev remains when nothing is recorded, as in a copy without git.
• UDP connected: over UDP (server start --udp, with one model or several) the event log said connected with an empty remote as soon as the socket was served, before any master had sent anything. It now says connected when the first datagram arrives, naming its sender as remote (at once, naming the master, with --udp-peer); a socket no master sent to logs neither connected nor disconnected.
• server start --dial with --duration: the goroutine that dials the master read the context that --duration replaces, a data race the race detector reports; it now gets its context before it starts.

Upgrade notes

• No breaking changes. A script that read usage errors from stderr while passing --format json now finds them on stdout, as every other error.