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ENetConnection

Inherits: RefCounted < Object

A wrapper class for an ENetHost.

Description

ENet's purpose is to provide a relatively thin, simple and robust network communication layer on top of UDP (User Datagram Protocol).

Tutorials

• API documentation on the ENet website

Methods

void	bandwidth_limit(in_bandwidth: int = 0, out_bandwidth: int = 0)
void	broadcast(channel: int, packet: PackedByteArray, flags: int)
void	channel_limit(limit: int)
void	compress(mode: CompressionMode)
ENetPacketPeer	connect_to_host(address: String, port: int, channels: int = 0, data: int = 0)
Error	create_host(max_peers: int = 32, max_channels: int = 0, in_bandwidth: int = 0, out_bandwidth: int = 0)
Error	create_host_bound(bind_address: String, bind_port: int, max_peers: int = 32, max_channels: int = 0, in_bandwidth: int = 0, out_bandwidth: int = 0)
void	destroy()
Error	dtls_client_setup(hostname: String, client_options: TLSOptions = null)
Error	dtls_server_setup(server_options: TLSOptions)
void	flush()
int	get_local_port() const
int	get_max_channels() const
Array[ENetPacketPeer]	get_peers()
float	pop_statistic(statistic: HostStatistic)
void	refuse_new_connections(refuse: bool)
Array	service(timeout: int = 0)
void	socket_send(destination_address: String, destination_port: int, packet: PackedByteArray)

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Enumerations

enum CompressionMode: 🔗

CompressionMode COMPRESS_NONE = 0

No compression. This uses the most bandwidth, but has the upside of requiring the fewest CPU resources. This option may also be used to make network debugging using tools like Wireshark easier.

CompressionMode COMPRESS_RANGE_CODER = 1

ENet's built-in range encoding. Works well on small packets, but is not the most efficient algorithm on packets larger than 4 KB.

CompressionMode COMPRESS_FASTLZ = 2

FastLZ compression. This option uses less CPU resources compared to COMPRESS_ZLIB, at the expense of using more bandwidth.

CompressionMode COMPRESS_ZLIB = 3

Zlib compression. This option uses less bandwidth compared to COMPRESS_FASTLZ, at the expense of using more CPU resources.

CompressionMode COMPRESS_ZSTD = 4

Zstandard compression. Note that this algorithm is not very efficient on packets smaller than 4 KB. Therefore, it's recommended to use other compression algorithms in most cases.

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enum EventType: 🔗

EventType EVENT_ERROR = -1

An error occurred during service. You will likely need to destroy the host and recreate it.

EventType EVENT_NONE = 0

No event occurred within the specified time limit.

EventType EVENT_CONNECT = 1

A connection request initiated by enet_host_connect has completed. The array will contain the peer which successfully connected.

EventType EVENT_DISCONNECT = 2

A peer has disconnected. This event is generated on a successful completion of a disconnect initiated by ENetPacketPeer.peer_disconnect, if a peer has timed out, or if a connection request initialized by connect_to_host has timed out. The array will contain the peer which disconnected. The data field contains user supplied data describing the disconnection, or 0, if none is available.

EventType EVENT_RECEIVE = 3

A packet has been received from a peer. The array will contain the peer which sent the packet and the channel number upon which the packet was received. The received packet will be queued to the associated ENetPacketPeer.

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enum HostStatistic: 🔗

HostStatistic HOST_TOTAL_SENT_DATA = 0

Total data sent.

HostStatistic HOST_TOTAL_SENT_PACKETS = 1

Total UDP packets sent.

HostStatistic HOST_TOTAL_RECEIVED_DATA = 2

Total data received.

HostStatistic HOST_TOTAL_RECEIVED_PACKETS = 3

Total UDP packets received.

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Method Descriptions

void bandwidth_limit(in_bandwidth: int = 0, out_bandwidth: int = 0) 🔗

Adjusts the bandwidth limits of a host.

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void broadcast(channel: int, packet: PackedByteArray, flags: int) 🔗

Queues a packet to be sent to all peers associated with the host over the specified channel. See ENetPacketPeer FLAG_* constants for available packet flags.

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void channel_limit(limit: int) 🔗

Limits the maximum allowed channels of future incoming connections.

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void compress(mode: CompressionMode) 🔗

Sets the compression method used for network packets. These have different tradeoffs of compression speed versus bandwidth, you may need to test which one works best for your use case if you use compression at all.

Note: Most games' network design involve sending many small packets frequently (smaller than 4 KB each). If in doubt, it is recommended to keep the default compression algorithm as it works best on these small packets.

Note: The compression mode must be set to the same value on both the server and all its clients. Clients will fail to connect if the compression mode set on the client differs from the one set on the server.

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ENetPacketPeer connect_to_host(address: String, port: int, channels: int = 0, data: int = 0) 🔗

Initiates a connection to a foreign address using the specified port and allocating the requested channels. Optional data can be passed during connection in the form of a 32 bit integer.

Note: You must call either create_host or create_host_bound on both ends before calling this method.

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Error create_host(max_peers: int = 32, max_channels: int = 0, in_bandwidth: int = 0, out_bandwidth: int = 0) 🔗

Creates an ENetHost that allows up to max_peers connected peers, each allocating up to max_channels channels, optionally limiting bandwidth to in_bandwidth and out_bandwidth (if greater than zero).

This method binds a random available dynamic UDP port on the host machine at the unspecified address. Use create_host_bound to specify the address and port.

Note: It is necessary to create a host in both client and server in order to establish a connection.

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Error create_host_bound(bind_address: String, bind_port: int, max_peers: int = 32, max_channels: int = 0, in_bandwidth: int = 0, out_bandwidth: int = 0) 🔗

Creates an ENetHost bound to the given bind_address and bind_port that allows up to max_peers connected peers, each allocating up to max_channels channels, optionally limiting bandwidth to in_bandwidth and out_bandwidth (if greater than zero).

Note: It is necessary to create a host in both client and server in order to establish a connection.

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void destroy() 🔗

Destroys the host and all resources associated with it.

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Error dtls_client_setup(hostname: String, client_options: TLSOptions = null) 🔗

Configure this ENetHost to use the custom Godot extension allowing DTLS encryption for ENet clients. Call this before connect_to_host to have ENet connect using DTLS validating the server certificate against hostname. You can pass the optional client_options parameter to customize the trusted certification authorities, or disable the common name verification. See TLSOptions.client and TLSOptions.client_unsafe.

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Error dtls_server_setup(server_options: TLSOptions) 🔗

Configure this ENetHost to use the custom Godot extension allowing DTLS encryption for ENet servers. Call this right after create_host_bound to have ENet expect peers to connect using DTLS. See TLSOptions.server.

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void flush() 🔗

Sends any queued packets on the host specified to its designated peers.

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int get_local_port() const 🔗

Returns the local port to which this peer is bound.

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int get_max_channels() const 🔗

Returns the maximum number of channels allowed for connected peers.

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Array[ENetPacketPeer] get_peers() 🔗

Returns the list of peers associated with this host.

Note: This list might include some peers that are not fully connected or are still being disconnected.

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float pop_statistic(statistic: HostStatistic) 🔗

Returns and resets host statistics. See HostStatistic for more info.

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void refuse_new_connections(refuse: bool) 🔗

Configures the DTLS server to automatically drop new connections.

Note: This method is only relevant after calling dtls_server_setup.

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Array service(timeout: int = 0) 🔗

Waits for events on this connection and shuttles packets between the host and its peers, with the given timeout (in milliseconds). The returned Array will have 4 elements. An EventType, the ENetPacketPeer which generated the event, the event associated data (if any), the event associated channel (if any). If the generated event is EVENT_RECEIVE, the received packet will be queued to the associated ENetPacketPeer.

Call this function regularly to handle connections, disconnections, and to receive new packets.

Note: This method must be called on both ends involved in the event (sending and receiving hosts).

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void socket_send(destination_address: String, destination_port: int, packet: PackedByteArray) 🔗

Sends a packet toward a destination from the address and port currently bound by this ENetConnection instance.

This is useful as it serves to establish entries in NAT routing tables on all devices between this bound instance and the public facing internet, allowing a prospective client's connection packets to be routed backward through the NAT device(s) between the public internet and this host.

This requires forward knowledge of a prospective client's address and communication port as seen by the public internet - after any NAT devices have handled their connection request. This information can be obtained by a STUN service, and must be handed off to your host by an entity that is not the prospective client. This will never work for a client behind a Symmetric NAT due to the nature of the Symmetric NAT routing algorithm, as their IP and Port cannot be known beforehand.