oppo-multiplexer

Multiplexes client connections onto a single TCP connection to the Oppo Blu-ray Player, broadcasting unsolicited updates to all clients.

Build

Requires Rust.

cargo build --release

The binary will be at target/release/oppo-multiplexer.

Run

oppo-multiplexer <listen_port> <backend_host:backend_port> <timeout_seconds> [max_consecutive_timeouts] [--protocol udp20x|magnetar]

• listen_port - port to accept incoming client connections on
• backend_host:backend_port - address of the Oppo player
• timeout_seconds - how long to wait for a response from the player before giving up
• max_consecutive_timeouts - optional; reconnect backend only after this many consecutive timed-out requests (default: 3, must be in the range 1-100)
• --protocol - optional; the player's control protocol (default: udp20x). One instance serves one player, so this is fixed per instance:

  • udp20x - Oppo UDP-203/205 IP protocol: #CODE\r commands, \r-terminated @… responses, and @U?? unsolicited updates broadcast to all clients.

  • magnetar - Magnetar network protocol: #CODE\r\n commands. The player answers each with a bare ack carrying no state, so the proxy acks each client immediately without waiting for it. It still multiplexes because Magnetar, like the Oppo players, accepts only one control connection.

    On each backend connect, the proxy also sends #APP\r\n (undocumented handshake), which switches the player into pushing unsolicited <message>...</message> XML blocks with playback/volume state on that connection. These are broadcast to all clients, same as Oppo's @U?? updates.

    Liveness note: because ordinary Magnetar commands get no meaningful response, there is nothing to time out on, so the max_consecutive_timeouts reconnect does not apply to them. A backend that dies cleanly (FIN/RST) is detected and reconnected, but a silently black-holed player cannot be detected at the application layer from command traffic alone - commands are ack'd even if the player never received them. This is inherent to a fire-and-forget command protocol; the metadata push, once active, does at least reveal real player state.

Example:

oppo-multiplexer 23 192.168.1.50:23 10 5

Magnetar (listens on port 8102):

oppo-multiplexer 8102 192.168.1.50:8102 10 --protocol magnetar

Docker

A prebuilt multi-arch image (linux/amd64, linux/arm64) is published to Docker Hub as henrikwidlund/oppo-multiplexer on each v*.*.* tag. It is a static scratch image that runs as a non-root user.

Ports below 1024: the container runs as a non-root user (UID 65532), which cannot bind privileged ports inside the container. Have the app listen on a high port (e.g. 1024) and use Docker's port mapping to expose it on a low host port if needed - e.g. -p 23:1024 with command listening on 1024. The listen_port argument is the container port, and the left side of -p host:container is what clients connect to.

Arguments are passed the same way as the binary:

docker run --rm -p 23:1024 henrikwidlund/oppo-multiplexer \
  1024 192.168.1.50:23 10 5

Run detached:

docker run -d --name oppo -p 23:1024 --restart unless-stopped \
  henrikwidlund/oppo-multiplexer 1024 192.168.1.50:23 10 5

Or with Docker Compose:

services:
  oppo-multiplexer:
    image: henrikwidlund/oppo-multiplexer
    ports: ["23:1024"]
    command: ["1024", "192.168.1.50:23", "10", "5"]
    restart: unless-stopped
    environment:
      RUST_LOG: info

Logs go to stderr (journald is not available in the container).

Building the image locally

docker build -t oppo-multiplexer:local .
docker run --rm -p 23:1024 oppo-multiplexer:local 1024 192.168.1.50:23 10 5

Installing on Linux

Download install_linux.sh and follow the instructions. If you want to run on ports below 1024, you will need to run as root. You can use the CAP_NET_BIND_SERVICE capability to avoid root on ports below 1024, but the script does not take this into consideration.

Logging

Log level is controlled via the RUST_LOG environment variable. Defaults to info. On Linux, logs are sent to journald.

RUST_LOG=debug oppo-multiplexer 23 192.168.1.50:23 10