Packet.Rhp2 0.36.0

Packet.Rhp2

The RHPv2 (Radio Host Protocol v2) JSON-over-TCP wire codec.

Packet.Rhp2 is the single source of truth for the RHPv2 (PWP-0222 / PWP-0245) wire format: framing, the message catalogue, JSON serialization, and payload encoding - with no engine, no transport, and no client/server policy. It is the shared codec layer that both RHPv2 servers and RHPv2 clients build on. Part of Packet.NET, a .NET amateur-radio / AX.25 packet stack.

Install

dotnet add package Packet.Rhp2

Quick start

Build a typed message, serialize it to JSON, and write it as one length-prefixed frame; on the way back, read a frame and dispatch on its type.

using Packet.Rhp2;

// --- send: connect a socket handle to a remote station ---
var connect = new ConnectMessage { Id = 1, Handle = 1234, Remote = "Q0PDN-1" };
byte[] json = RhpJson.Serialize(connect);          // type-first UTF-8 JSON
await RhpFraming.WriteFrameAsync(stream, json);     // 2-byte BE length + bytes

// --- send binary payload: data goes in the JSON `data` field as Latin-1, not base64 ---
var send = new SendMessage { Id = 2, Handle = 1234, Data = RhpDataEncoding.ToWireString(payloadBytes) };
await RhpFraming.WriteFrameAsync(stream, RhpJson.Serialize(send));

// --- receive: one frame, then dispatch on the concrete type ---
byte[]? frame = await RhpFraming.ReadFrameAsync(stream);   // null = peer hung up between frames
if (frame is not null)
{
    RhpMessage msg = RhpJson.Deserialize(frame);
    switch (msg)
    {
        case ConnectReplyMessage r when r.ErrCode == RhpErrorCode.Ok:
            // connected
            break;
        case RecvMessage rx:
            byte[] data = RhpDataEncoding.FromWireString(rx.Data);
            break;
        case UnknownMessage u:
            // forward-compatible: a newer XRouter added a type we don't model
            break;
    }
}

ReadFrameAsync returns null at a clean end-of-stream (the normal way an RHP conversation ends) and throws EndOfStreamException only when a peer hangs up mid-frame. An overload takes an in-frame timeout to drop a slowloris peer without bounding idle-between-frames waits.

Key types

• RhpFraming - read/write one length-prefixed frame (2-byte big-endian length + UTF-8 JSON); zero-length frames are legal.
• RhpJson - serialize/deserialize RhpMessage DTOs; type-first key emission, null omission, case-insensitive reads.
• RhpMessage - abstract base for every message; subclasses (AuthMessage, OpenMessage, ConnectMessage, SendMessage, RecvMessage, … and their replies) map one-to-one to the type discriminators.
• UnknownMessage - carries the raw JSON for an unrecognised type instead of throwing (forward-compatible).
• RhpDataEncoding - bytes ↔ the JSON data field via Latin-1 (one byte per code unit). Not base64.
• RhpConstants - ProtocolFamily, SocketMode, OpenFlags, StatusFlags, RhpErrorCode (with canonical Text()), RhpMessageType.
• RhpProtocolException - thrown for a codec-level violation (non-object JSON, missing type), but never for a merely unknown type.

Wire fidelity

The shapes here are pinned against live XRouter, not just the published spec: capital errCode / errText on every reply (read case-insensitively so the spec's lowercase form still parses), the connectReply PascalCase-typo tolerance on read, port string-or-number normalisation, errCode 17 "Not connected", and the Latin-1 (not base64) data encoding.

See also

• Source & issues
• Packet.NetRom - NET/ROM layer 3/4
• Packet.Ax25 - the AX.25 link layer underneath

AGPL-3.0-licensed. Part of the Packet.NET stack.