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OWSD web socket daemon

This is a fork of http://public.inteno.se/owsd.git without SSL, ubus-proxy and dbus support. OpenWrt build files that do a static link against libwebsockets are in openwrt.

The final .ipkg is only 53kb and has no dependencies

Usage:

feeds.conf:

src-git owsd https://gitlab.bau-ha.us/mt/owsd-tiny

.config:

CONFIG_PACKAGE_owsd=y

Overview

  • uses web sockets to accept RPC calls in JSON-RPC
  • intended as web back-end for Inteno JUCI Web UI on OpenWrt based platform experiments :)
  • RPCs are routed to local IPC bus objects on ubus
  • supports receiving events in addition to issuing method calls
  • uses ubus session object to perform access control
  • JSON-RPC format is compatible with uhttpd-mod-ubus
  • basic HTTP file serving logic is available
  • powered by libwebsockets, libubox, libubus

Supported RPCs

  • "list"
  • "call"
  • "subscribe"
    • start listening for broadcast events by glob (wildcard) pattern
  • "subscribe-list"
    • list which events we are listening for
  • "unsubscribe"
    • stop listening

ubus support

  • methods on ubus objects can be called via the "call" rpc
  • events sent via ubus_send_event can be received
  • ACL checks are made prior to calling methods on ubus objects - the ubus session object is accessed to verify if session ID field has access
  • ACL checks are also made prior to notifying clients of events they are listening for - "owsd" is used as the scope to check for "read" permission on the event

ubus proxy support - networked ubus

  • using ubus proxy support, ubus objects can be proxied over the network across two hosts
  • with two hosts, client with ubus proxy support connects to remote server, and lists available objects
  • remotely available objects are created on the local client's ubus, calling methods of these (stub) objects results in RPC calls to the server's objects
  • see this screencast

Manual test run

If you run the owsd as RPC server to listen on some port (e.g. 1234)

owsd -p 1234

then it is easiest to test/connect with a tool like wscat:

wscat -c 'ws://127.0.0.1' -s ubus-json

The established web socket can be used to send RPCs in the JSON format.

Tests

In the test/ subdirectory, there is a very simple test runner made in nodejs. It is configured by editing parameters config.js, and running:

node client.js [session-id]

The config.js file specifies the text file containing test input and expected output. See existing text files for examples of RPC commands.

Other resources: libwebsockets documentation

https://libwebsockets.org/lws-api-doc-master/html/md_README.coding.html