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WebRTCPeerConnection

Inherits: RefCounted < Object

Inherited By: WebRTCPeerConnectionExtension

Interface to a WebRTC peer connection.

Description

A WebRTC connection between the local computer and a remote peer. Provides an interface to connect, maintain and monitor the connection.

Setting up a WebRTC connection between two peers from now on) may not seem a trivial task, but it can be broken down into 3 main steps:

• The peer that wants to initiate the connection (A from now on) creates an offer and send it to the other peer (B from now on).

• B receives the offer, generate and answer, and sends it to A).

• A and B then generates and exchange ICE candidates with each other.

After these steps, the connection should become connected. Keep on reading or look into the tutorial for more information.

Methods

Signals

data_channel_received ( WebRTCDataChannel channel )

Emitted when a new in-band channel is received, i.e. when the channel was created with negotiated: false (default).

The object will be an instance of WebRTCDataChannel. You must keep a reference of it or it will be closed automatically. See create_data_channel.

ice_candidate_created ( String media, int index, String name )

Emitted when a new ICE candidate has been created. The three parameters are meant to be passed to the remote peer over the signaling server.

session_description_created ( String type, String sdp )

Emitted after a successful call to create_offer or set_remote_description (when it generates an answer). The parameters are meant to be passed to set_local_description on this object, and sent to the remote peer over the signaling server.

Enumerations

enum ConnectionState:

ConnectionState STATE_NEW = 0

The connection is new, data channels and an offer can be created in this state.

ConnectionState STATE_CONNECTING = 1

The peer is connecting, ICE is in progress, none of the transports has failed.

ConnectionState STATE_CONNECTED = 2

The peer is connected, all ICE transports are connected.

ConnectionState STATE_DISCONNECTED = 3

At least one ICE transport is disconnected.

ConnectionState STATE_FAILED = 4

One or more of the ICE transports failed.

ConnectionState STATE_CLOSED = 5

The peer connection is closed (after calling close for example).

enum GatheringState:

GatheringState GATHERING_STATE_NEW = 0

The peer connection was just created and hasn’t done any networking yet.

GatheringState GATHERING_STATE_GATHERING = 1

The ICE agent is in the process of gathering candidates for the connection.

GatheringState GATHERING_STATE_COMPLETE = 2

The ICE agent has finished gathering candidates. If something happens that requires collecting new candidates, such as a new interface being added or the addition of a new ICE server, the state will revert to gathering to gather those candidates.

enum SignalingState:

SignalingState SIGNALING_STATE_STABLE = 0

There is no ongoing exchange of offer and answer underway. This may mean that the WebRTCPeerConnection is new (STATE_NEW) or that negotiation is complete and a connection has been established (STATE_CONNECTED).

SignalingState SIGNALING_STATE_HAVE_LOCAL_OFFER = 1

The local peer has called set_local_description, passing in SDP representing an offer (usually created by calling create_offer), and the offer has been applied successfully.

SignalingState SIGNALING_STATE_HAVE_REMOTE_OFFER = 2

The remote peer has created an offer and used the signaling server to deliver it to the local peer, which has set the offer as the remote description by calling set_remote_description.

SignalingState SIGNALING_STATE_HAVE_LOCAL_PRANSWER = 3

The offer sent by the remote peer has been applied and an answer has been created and applied by calling set_local_description. This provisional answer describes the supported media formats and so forth, but may not have a complete set of ICE candidates included. Further candidates will be delivered separately later.

SignalingState SIGNALING_STATE_HAVE_REMOTE_PRANSWER = 4

A provisional answer has been received and successfully applied in response to an offer previously sent and established by calling set_local_description.

SignalingState SIGNALING_STATE_CLOSED = 5

The WebRTCPeerConnection has been closed.

Method Descriptions

Error add_ice_candidate ( String media, int index, String name )

Add an ice candidate generated by a remote peer (and received over the signaling server). See ice_candidate_created.

void close ( )

Close the peer connection and all data channels associated with it.

Note: You cannot reuse this object for a new connection unless you call initialize.

WebRTCDataChannel create_data_channel ( String label, Dictionary options={} )

Returns a new WebRTCDataChannel (or null on failure) with given label and optionally configured via the options dictionary. This method can only be called when the connection is in state STATE_NEW.

There are two ways to create a working data channel: either call create_data_channel on only one of the peer and listen to data_channel_received on the other, or call create_data_channel on both peers, with the same values, and the "negotiated" option set to true.

Valid options are:

{
    "negotiated": true, # When set to true (default off), means the channel is negotiated out of band. "id" must be set too. "data_channel_received" will not be called.
    "id": 1, # When "negotiated" is true this value must also be set to the same value on both peer.
    # Only one of maxRetransmits and maxPacketLifeTime can be specified, not both. They make the channel unreliable (but also better at real time).
    "maxRetransmits": 1, # Specify the maximum number of attempt the peer will make to retransmits packets if they are not acknowledged.
    "maxPacketLifeTime": 100, # Specify the maximum amount of time before giving up retransmitions of unacknowledged packets (in milliseconds).
    "ordered": true, # When in unreliable mode (i.e. either "maxRetransmits" or "maxPacketLifetime" is set), "ordered" (true by default) specify if packet ordering is to be enforced.
    "protocol": "my-custom-protocol", # A custom sub-protocol string for this channel.
}

Note: You must keep a reference to channels created this way, or it will be closed.

Error create_offer ( )

Creates a new SDP offer to start a WebRTC connection with a remote peer. At least one WebRTCDataChannel must have been created before calling this method.

If this functions returns @GlobalScope.OK, session_description_created will be called when the session is ready to be sent.

ConnectionState get_connection_state ( ) const

Returns the connection state. See ConnectionState.

GatheringState get_gathering_state ( ) const

Returns the ICE GatheringState of the connection. This lets you detect, for example, when collection of ICE candidates has finished.

SignalingState get_signaling_state ( ) const

Returns the SignalingState on the local end of the connection while connecting or reconnecting to another peer.

Error initialize ( Dictionary configuration={} )

Re-initialize this peer connection, closing any previously active connection, and going back to state STATE_NEW. A dictionary of configuration options can be passed to configure the peer connection.

Valid configuration options are:

{
    "iceServers": [
        {
            "urls": [ "stun:stun.example.com:3478" ], # One or more STUN servers.
        },
        {
            "urls": [ "turn:turn.example.com:3478" ], # One or more TURN servers.
            "username": "a_username", # Optional username for the TURN server.
            "credential": "a_password", # Optional password for the TURN server.
        }
    ]
}

Error poll ( )

Call this method frequently (e.g. in Node._process or Node._physics_process) to properly receive signals.

void set_default_extension ( StringName extension_class ) static

Sets the extension_class as the default WebRTCPeerConnectionExtension returned when creating a new WebRTCPeerConnection.

Error set_local_description ( String type, String sdp )

Sets the SDP description of the local peer. This should be called in response to session_description_created.

After calling this function the peer will start emitting ice_candidate_created (unless an Error different from @GlobalScope.OK is returned).

Error set_remote_description ( String type, String sdp )

Sets the SDP description of the remote peer. This should be called with the values generated by a remote peer and received over the signaling server.

If type is "offer" the peer will emit session_description_created with the appropriate answer.

If type is "answer" the peer will start emitting ice_candidate_created.