netconf

NETCONF support libraries for golang

Support libraries for writing NETCONF applications in Go.

Install

Add to your go module, running the tests to be sure.

# add netconf package to your go module
$ go get github.com/andaru/netconf
# run the tests
$ (go test github.com/andaru/netconf/... && echo "OK: tests passed") || echo "FAIL: uhoh, tests failed"

Introduction

With these libraries, it's easy to build NETCONF applications.

By taking care of the messy and inconvenient parts of NETCONF transport and message handling, these libraries let you write fully-featured NETCONF clients and servers with support for any underlying network transport.

Quickstart

Client

• Instantiate a new session.Session using an io.Reader and io.WriteCloser from your transport (client or server), typically via SSH or TLS.

import (
  "log"

  "github.com/andaru/netconf/session"
)

type ClientHandler struct {
  // any local client state goes here
}

func (h *ClientHandler) OnEstablished(s *session.Session) {
  // called once by the session runner, after session start-up, framing mode and capabilities exchange
  for _, capabilityString := range s.State.Capabilties {
    // inspect the remote peer's capabilities against your own (s.Config.Capabilities)
  }
  // use the established trigger an RPC request immediately (alternatively, start an RPC request sender
  // goroutine to run alongside the client handler, using the OnClose handler method to shut it down)
  _, err := s.Outgoing().Write([]byte(`<rpc xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">...</rpc>`))
}

// OnMessage is called for each message received by the session from the peer
func (h *ClientHandler) OnMessage(s *session.Session) {
  // Consider use of the github.com/antchfx/xmlquery package instead of io.ReadAll to
  // parse NETCONF response XML data from the server (<rpc-reply> elements).

  // read the entire message (all chunks, when in chunked mode)
  _, err := io.ReadAll(s.Incoming())
  // typical read error handling
  if err != nil {
    if err != session.ErrEndOfStream {
      s.AddError(err)
      // abnormal session termination occurred (likely a transport error)
    }
    // move the status to error state, which will terminate the session and call OnError()
    s.State.Status = session.StatusError
    return
  }
  // otherwise, handle server response, then...
  // send another request (default server capabilities require <rpc> to be sent one at a time)...
}

// OnError is called when the session status changes to session.StatusError
func (h *ClientHandler) OnError(s *session.Session) { /* look at s.Errors() */ }

// OnClose is called when the session status changes to session.StatusClosed
func (h *ClientHandler) OnClose(s *session.Session) {}

func main() {
  // setup transport io.Reader as r, io.WriteCloser as w
  clientHandler := &ClientHandler{}
  // Create a NETCONF session with base and chunked capabilities
  s := session.New(r, w, session.Config{
    Capabilities: {
      "urn:ietf:params:netconf:base:1.0", // required by all clients
      "urn:ietf:params:netconf:base:1.1" // your client will support chunked encoding
    },
  })
  // Run our client handler on the session
  s.Run(clientHandler)
}

Key Features

• NETCONF stream decoders and encoders with full NETCONF 1.1 support
• Support for both NETCONF :base:1.0 (aka end of message delimited) and :base:1.1 (aka chunked) framing.
• A NETCONF session.Session type with corresponding session.Handler interface.
  • Performs session initialization (<hello> and <capabilities> exchange) and session validation common to both client and server sessions, as well as any required framing mode switch.
  • Allows NETCONF application development based on session.Handler event handlers along with access to the session's current Incoming and Outgoing messages (as handler callback arguments).
  • Supports both client and server session customization.
  • Use *xml.Decoder or any other consumer supporting an io.Reader source to consume NETCONF messages.
  • Use *xml.Encoder or any other producer supporting an io.WriteCloser destination to produce NETCONF messages.

Related libraries under development

• A streaming gRPC protocol for passing transport data
  • Allows e.g., openssh calling a small binary using the protocol client to call into a central NETCONF management agent running the protocol server
• A document object model (perhaps an extension of xmlquery)
• Encoding, decoding and validation of YANG data, including:
  • [RFC6020 XML][https://tools.ietf.org/html/rfc6020] and [RFC7951 JSON][https://tools.ietf.org/html/rfc7951] encoding and decoding of YANG data.