aos/network/web_proxy.fbs

// Typescript namespaces are weird when coming from multiple files. We generate
// all transitive dependencies into the same file in typescript so we can
// include all 'aos' flatbuffers we care about here.
include "aos/configuration.fbs";
include "aos/network/connect.fbs";

namespace aos.web_proxy;

// SDP is Session Description Protocol. We only handle OFFER (starting a
// transaction) and ANSWER responding to an offer.
enum SdpType : byte {
  OFFER,
  ANSWER
}

// The SDP payload is an opaque string that describes what (media/data) we
// want to transmit.
table WebSocketSdp {
  type:SdpType;
  payload:string;
}

// ICE is way for different peers to learn how to connect to each other.
// Because we will only be running in a local network, we don't have to support
// advaced features.
table WebSocketIce {
  candidate:string;
  sdpMid:string;
  sdpMLineIndex:int;
}

union Payload {WebSocketSdp, WebSocketIce}

// We only send a single type of message on the websocket to simplify parsing.
table WebSocketMessage {
  payload:Payload;
}

// WebRTC has size limits on the messages sent on datachannels. This message
// ensures that parts are recieved in the correct order. If there is any
// mismatch, all the existing work should be dropped and restart when reasonable
// data starts again.
table MessageHeader {
  // Index of the channel in config
  channel_index:uint;

  // How many packets will be required for the message being sent.
  packet_count:uint;
  // What index into the the total packets for the multipart message, this
  // header is parts of.
  packet_index:uint;

  // Total number of bytes in the message
  length:uint;

  // Index into the sequence of messages. This will not always increase.
  queue_index:uint;

  data:[ubyte];

  // Time at which the message was sent, in nanoseconds.
  monotonic_sent_time:long;
}