syntax = "proto3";

/*
  There are four types of messages that palm can send.
    1. Unencrypted reflection. This is unencrypted communication between a relay and a client.
    2. Encrypted reflection. This is encrypted communication between a relay and a client.
    3. Unencrypted tunnel. This is unencrypted communication between a client and a client, through a relay. Note that it is encrypted both ways via encrypted reflection.
    4. Encrypted tunnel. This is doubly-encrypted communcation between a client and a client, through a relay.

  The following convention is used:
    C2R Client to Relay - Reflection
    R2C Relay to Client - Reflection
    I2R Initiating Client to Receiving Client - Tunneled
    R2I Receiving Client to Initiating Client - Tunneled
 */

/////// UNENCRYPTED REFLECTION ///////

// Sent by client at start of connection
message PalmC2RHandshakeStart {
  bytes ClientPublicKey = 1;  // 32-byte X25519 public key
  bytes SessionIV = 2;        // 12-byte randomized IV generated by the client
  bytes Check = 3;            // 32-byte randomized value used to check encryption
}

// Sent by relay in response to PalmC2RHandshakeStart
message PalmR2CHandshakeFinish {
  bytes ServerPublicKey = 1;  // 32-byte X25519 public key
  bytes Check = 2;            // The same 32-byte value provided in PalmC2SHandshakeStart, used to tie this response to the original session
}

/////// ENCRYPTED REFLECTED MESSAGES ///////

// Sent by client after receiving PalmR2CHandshakeFinish.
// Used by the client to request a room on the server.
message PalmC2RRelayRequest {
  bytes Check = 1;            // The same 32-byte value used in initial reflected handshake, ties this to the session.
  string ChannelID = 2;       // The string channel ID this client is requested to be routed to.
}

// Represents the states a room/channel can be in.
enum PalmRoomStatus {
  NotReady = 0;               // Waiting for a peer to join
  Ready = 1;                  // A peer has joined, and the relay is ready to relay the connection
  InUse = 2;                  // This channel is already in use and cannot be used currently
}

// Send at *any time* by the server to indicate the current status of the server.
// Must also be sent in response to PalmC2RRelayRequest to indicate the current status of the room.
// If the other peer is disconnected, PalmR2CChannelStatus will be sent again with Status = NotReady;
// The client must handle this correctly.
message PalmR2CChannelStatus {
  bytes Check = 1;            // The same 32-byte value used in previous packets, ties this packet to the session.
  string ChannelID = 2;       // The channel that the client requested.
  PalmRoomStatus Status = 3;  // The current status of the room.
}