Networking Messages

Networking API intended to make it easy to port non-connection-oriented code to take advantage of P2P connectivity and Steam Datagram Relay. These are part of the newer networking classes; not to be confused with the older, now-deprecated Networking class.

Networking Sockets is connection-oriented (like TCP), meaning you need to listen and connect, and then you send messages using a connection handle. Networking Messages, on the other hand, is more like UDP, in that you can just send messages to arbitrary peers at any time. The underlying connections are established implicitly.

Under the hood Networking Messages works on top of the Networking Sockets code, so you get the same routing and messaging efficiency. The difference is mainly in your responsibility to explicitly establish a connection and the type of feedback you get about the state of the connection. Both interfaces can do "P2P" communications, both support both unreliable and reliable messages, fragmentation and reassembly, and both can be used to take advantage of Steam Datagram Relay to talk to dedicated servers.

The primary purpose of this interface is to be "like UDP", so that UDP-based code can be ported easily to take advantage of relayed connections. If you find yourself needing more low level information or control, or to be able to better handle failure, then you probably need to use Networking Sockets directly. Also, note that if your main goal is to obtain a connection between two peers without concerning yourself with assigning roles of "client" and "server", you may find the symmetric connection mode of Networking Sockets useful. See NETWORKING_CONFIG_SYMMETRIC_CONNECT.

Only available in the main GodotSteam branches and GodotSteam Server branches

Functions

acceptSessionWithUser

acceptSessionWithUser( uint64_t remote_steam_id )

Parameter	Type	Notes
remote_steam_id	uint64_t	The Steam ID of the user to accept a Messages session with.

Call this in response to a network_messages_session_request callback. network_messages_session_request callbacks are posted when a user tries to send you a message, and you haven't tried to talk to them first. If you don't want to talk to them, just ignore the request. If the user continues to send you messages, network_messages_session_request callbacks will continue to be posted periodically.

Calling sendMessageToUser will implicitly accept any pending session request to that user.

Returns: bool

Returns true if there is an existing active session, even if it is not pending; otherwise, false if there is no session with the user pending or otherwise.

closeChannelWithUser

closeChannelWithUser( uint64_t remote_steam_id, int channel )

Parameter	Type	Notes
remote_steam_id	uint64_t	The Steam ID of the user to close the channel with.
channel	int	The channel to close.

Call this when you're done talking to a user on a specific channel. Once all open channels to a user have been closed, the open session to the user will be closed, and any new data from this user will trigger a network_messages_session_request callback.

Returns: bool

closeSessionWithUser

closeSessionWithUser( uint64_t remote_steam_id )

Parameter	Type	Notes
remote_staem_id	uint64_t	The Steam ID of the user to close the session with.

Call this when you're done talking to a user to immediately free up resources under-the-hood. If the remote user tries to send data to you again, another network_messages_session_request callback will be posted.

Sessions that go unused for a few minutes are automatically timed out.

Returns: bool

getSessionConnectionInfo

getSessionConnectionInfouint64_t remote_steam_id, bool get_connection, bool get_status )

Parameter	Type	Notes
remote_steam_id	uint64_t	The Steam ID of the user to get connection info for.
get_connection	bool	Get the connection information.
get_status	bool	Get the connection status.

Returns information about the latest state of a connection, if any, with the given peer. Primarily intended for debugging purposes but can also be used to get more detailed failure information.

You may pass false for either get_connection or get_status if you do not need the corresponding details.

Sessions time out after a while, so if a connection fails or sendMessageToUser returns 3, you cannot wait indefinitely to obtain the reason for failure.

Returns: dictionary

Contains the following keys:

Key	Type	Notes
connection_state	NetworkingConnectionState enum	The value of connection state or 0 if no connection exists with specified peer.

If get_connection is true, also contains the following keys:

Key	Type	Notes
identity	uint64_t	Who is on the other end? Depending on the connection type and phase of the connection, we might not know.
user_data	uint64_t	Arbitrary user data set by the local application code.
listen_socket	uint32_t	Handle to listen socket this was connected on or LISTEN_SOCKET_INVALID if we initiated the connection.
remote_address	string	Remote address. Might be all 0's if we don't know it or if this is N/A; eg. basically everything except direct UDP connection.
remote_pop	uint32_t	What data center is the remote host in? 0 if we don't know.
pop_relay	uint32_t	What relay are we using to communicate with the remote host? 0 if not applicable.
connection_state	int	High level state of the connection.
end_reason	NetworkingConnectionEnd enum	Basic cause of the connection termination or problem.
end_debug	string	Human-readable but non-localized explanation for connection termination or problem. This is intended for debugging / diagnostic purposes only, not to display to users. It might have some details specific to the issue.
debug_description	string	Debug description. This includes the internal connection ID, connection type (and peer information), and any name given to the connection by the app. This string is used in various internal logging messages.
info_flags	int	Misc flags. Bitmask of NETWORKING_CONNECTION_INFO_FLAG_.

If get_status is true, also contains the following keys:

Key	Type	Notes
state	NetworkingConnectionState enum	High level state of the connection.
ping	int	Current ping in milliseconds.
local_quality	float	Connection quality measured locally, 0 to 1. Percentage of packets delivered end-to-end in order).
remote_quality	float	Packet delivery success rate as observed from remote host.
packets_out_per_second	float	Current data rates from recent history.
bytes_out_per_second	float	Current data rates from recent history.
packets_in_per_second	float	Current data rates from recent history.
bytes_in_per_second	float	Current data rates from recent history.
send_rate	int	Estimate rate that we believe that we can send data to our peer. This could be significantly higher than bytes_out_per_second, meaning the capacity of the channel is higher than you are sending data and that's OK.
pending_unreliable	int	Number of bytes pending to be sent.
pending_reliable	int	Number of bytes pending to be sent.
send_unacknowledged_reliable	int	Number of bytes of reliable data that has been placed the wire but for which we have not yet received an acknowledgment and thus we may have to re-transmit.
queue_time	uint64_t	If you queued a message right now, approximately how long would that message wait in the queue before we actually started putting its data on the wire in a packet?

receiveMessagesOnChannel

receiveMessagesOnChannel( int channel, int max_messages )

Parameter	Type	Notes
channel	int	The channel to receive messages on.
max_messages	int	The maximum number of messages to receive.

Reads the next message that has been sent from another user via sendMessageToUser on the given channel.

Returns: array of dictionaries

Each contains the following keys:

Key	Type	Notes
payload	PackedByteArray	The message payload.
size	int	Size of the payload.
connection	uint32_t	What connection did this come from?
identity	uint64_t	The Steam ID of the user who sent the message.
receiver_user_data	uint64_t	The user data associated with the connection.
time_received	uint64_t	Local timestamp when the message was received.
message_number	uint64_t	Message number assigned by teh sender.
channel	int	The channel number the message was received on.
flags	int	Bitmask of NETWORKING_SEND_ flags; only the NETWORKING_SEND_RELIABLE bit is valid.

sendMessageToUser

sendMessageToUser( uint64_t remote_steam_id, PackedByteArray data, int flags, int channel )

Parameter	Type	Notes
remote_steam_id	uint64_t	The Steam ID of the user you want to send the message to.
data	PackedByteArray	The packet data to send.
flags	int	Bitmask of NETWORKING_SEND_ options.
channel	int	Routing number you can use to help route message to different systems. You'll have to call receiveMessagesOnChannel with the same channel number in order to retrieve the data on the other end.

Sends a message to the specified host via identity_reference. If we don't already have a session with that user, a session is implicitly created. There might be some handshaking that needs to happen before we can actually begin sending message data. If this handshaking fails and we can't get through, an error will be posted via the callback network_messages_session_failed. There is no notification when the operation succeeds. You should have the peer send a reply for this purpose.

Sending a message to a host will also implicitly accept any incoming connection from that host.

Using different channels to talk to the same user will still use the same underlying connection, saving on resources. If you don't need this feature, use 0. Otherwise, small integers are the most efficient.

It is guaranteed that reliable messages to the same host on the same channel will be be received by the remote host, if they are received at all, exactly once and in the same order that they were sent.

No other order guarantees exist. In particular, unreliable messages may be dropped, received out of order with respect to each other and with respect to reliable data, or may be received multiple times. Messages on different channels are not guaranteed to be received in the order they were sent.

A note for those familiar with TCP/IP ports, or converting an existing codebase that opened multiple sockets: You might notice that there is only one channel, and with TCP/IP each endpoint has a port number. You can think of the channel number as the destination port. If you need each message to also include a source port, so the recipient can route the reply, then just put that in your message. That is essentially how UDP works.

Returns: int

Possible results may be:

RESULT_OK on success.
RESULT_NO_CONNECTION if the session has failed or was closed by the peer and NETWORKING_SEND_AUTORESTART_BROKEN_SESSION was not specified. You can use getSessionConnectionInfo to get the details.) In order to acknowledge the broken session and start a new one, you must call closeSessionWithUser or you may repeat the call with NETWORKING_SEND_AUTORESTART_BROKEN_SESSION](main.md#constants). See NETWORKING_SEND_AUTORESTART_BROKEN_SESSION](main.md#constants) for more details.
RESULT_NO_CONNECTION will be returned if the session has failed or was closed by the peer and NETWORKING_SEND_AUTORESTART_BROKEN_SESSION](main.md#constants) is not used. You can use getSessionConnectionInfo to get the details. In order to acknowledge the broken session and start a new one, you must call closeSessionWithUser.
See sendMessageToConnection for more possible return values.

Signals

These callbacks require you to setup one of the three callback methods to receive them.

network_messages_session_request

Posted when a remote host is sending us a message, and we do not already have a session with them.

Returns

Key	Type	Notes
remote_steam_id	uint64_t	User who wants to talk to us.

network_messages_session_failed

Posted when we fail to establish a connection or we detect that communications have been disrupted it an unusual way. There is no notification when a peer proactively closes the session. "Closed by peer" is not a concept of UDP-style communications and Networking Messages is primarily intended to make porting UDP code easy.

Remember, callbacks are asynchronous. See notes on sendMessageToUser and NETWORKING_SEND_AUTORESTART_BROKEN_SESSION constant in particular.

Also, if a session times out due to inactivity, no callbacks will be posted. The only way to detect that this is happening is that querying the session state may return none, connecting, and findingroute again.

Returns

Key	Type	Notes
reason	NetworkingConnectionEnd enum	Basic cause of the connection termination or problem.
remote_steam_id	int	Who is on the other end? Depending on the connection type and phase of the connection, we might not know.
connection_state	NetworkingConnectionState enum	High level state of the connection.
debug_message	string	Human-readable but non-localized explanation for connection termination or problem. This is intended for debugging / diagnostic purposes only, not to display to users. It might have some details specific to the issue.