Low-level line framing for the OpenVPN management protocol.

This crate provides:

• [Frame] — a classified line from the management interface
• [FrameDecoder] — a stateless-ish [tokio_util::codec::Decoder] that splits the byte stream into [Frame] values
• Encoder primitives ([write_line], [write_block], [wire_safe], [escape], [quote]) for building wire-format commands

The decoder does not track which command was sent — it classifies each line purely from its content. Multi-line response accumulation (grouping Line/End sequences) is left to higher layers.

>CLIENT:ENV accumulation is handled here because the protocol guarantees atomicity for that block and the individual ENV lines are not meaningful on their own.

Decoding frames

use bytes::BytesMut;
use tokio_util::codec::Decoder;
use openvpn_mgmt_frame::{Frame, FrameDecoder};

let mut decoder = FrameDecoder::new();
let mut buf = BytesMut::from("SUCCESS: pid=1234\n>HOLD:Waiting for hold release:0\n");

assert_eq!(
    decoder.decode(&mut buf).unwrap(),
    Some(Frame::Success("pid=1234".to_string())),
);
assert_eq!(
    decoder.decode(&mut buf).unwrap(),
    Some(Frame::Notification {
        kind: "HOLD".to_string(),
        payload: "Waiting for hold release:0".to_string(),
    }),
);
assert_eq!(decoder.decode(&mut buf).unwrap(), None); // buffer drained

Encoding commands

use bytes::BytesMut;
use openvpn_mgmt_frame::{write_line, write_block, escape, quote, EncoderMode};

let mut buf = BytesMut::new();
write_line(&mut buf, "status 3");
assert_eq!(&buf[..], b"status 3\n");

buf.clear();
write_block(&mut buf, "client-auth 1 2", &["push-reply".to_string()], EncoderMode::Sanitize).unwrap();
assert_eq!(&buf[..], b"client-auth 1 2\npush-reply\nEND\n");