ubus (Rust)

Work in progress

This is a pure Rust library for implementing OpenWRT ubus clients.

Quick Try

1. make sure ubusd is running, and you are using root to run examples (or hack ubusd's ubusd_acl_check()) to skip root check, see above
2. make sure your rust toolchain is nightly, because I use the try_collect() features
3. cargo run --example=addserver - start the server
4. cargo run --example=invoke - invoke server's method and print result
5. cargo run --example=ubuscall ttt echo '{"1": true}' - another way to invoke server's method and print result
6. cargo run --example=subscribe - subscribe to server and get notifications

Supported

• High-level abstraction for lookup command
• High level abstraction for call command
• High level abstraction for server object
• High level abstraction for subscribe / notify commands
• Async with Tokio
• JSON support
• Strongly typed result

TODO

• unsubscribe / remove_server
• handle IO/channel errors better instead of panic

Technical Notes

This is a fork of shavac/ubus-rs, using allocations (Vec and String) to convert raw bytes to native rust types.

There are almost none documention about libubus, especially about server object. And the libubus source code has no comments at all... I draw a Figma from what I learned by reading source code and debugging.

This makes strong assumption that ubus only use limited size of types of Blob, and actual data is always json (Vec<BlobMsg>), to make parsing more specific:

• Blob with its most-significat-bit 1 is BlobMsg, which can represents json data
• Blob with its most-significat-bit 0 is UbusBlob, which has fixed size of types, no other types of Blob used in ubus, except the container Blob in UbusMsg
• UbusMsg always has a UbusMsgHeader, followed by a giant container Blob that has type 0
• The container Blob contains multiple UbusBlobs, and UbusBlobs' payload data type is tied to UbusBlobs' type
  • e.g. If UbusBlob has type STATUS, then its payload is a u32
  • e.g. If UbusBlob has type DATA, then its payload is multiple BlobMsgs, which can be converted to one json object

Seems only root can connect to ubusd? To tests and development, I add an early return 0; to beginning of ubusd_acl.c -> ubusd_acl_check() in ubusd to skip auth.

Signature varification is skipped, (ubusd also doesn't care about it), making transfer any valid json possible. This is the behaviour of libubus and ubus cli.

Seems ubusd even doesn't care about method existence, its server object's responsibilty to return a method not found status.