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"
  • lists available object and methods; identical to uhttpd-mod-ubus
• "call"
  • call method of an object; identical to uhttpd-mod-ubus
• "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