Networking

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Networking

The following functions and constants allow you to use Steam's Networking functionality.

Packets IO

These functions are provided for handling sending and receiving packets:

• steam_net_packet_get_data
• steam_net_packet_get_sender_id
• steam_net_packet_get_size
• steam_net_packet_receive
• steam_net_packet_send
• steam_net_packet_set_type

Session

The following functions allow handling P2P sessions:

• steam_net_accept_p2p_session
• steam_net_close_p2p_session
• steam_net_set_auto_accept_p2p_sessions

Constants

These are the constants used by this API:

• PacketType

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steam_net_packet_get_data

Copies the contents of last received packet to the given buffer. Data is copied to the start of the buffer (position remains unaffected), meaning that if you reuse the same buffer, you should "rewind" it prior to reading.

ℹ️ NOTE

If the buffer is not big enough to fit data, it will be resized automatically (the buffer needs to be created using the using the buffer_grow type).

Syntax:

steam_net_packet_get_data(buffer)

Argument	Type	Description
buffer	real	The buffer to write the incoming data to.

Returns:

bool

Example:

while (steam_net_packet_receive())
{
    steam_net_packet_get_data(inbuf);
    buffer_seek(inbuf, buffer_seek_start, 0);
    switch (buffer_read(inbuf, buffer_u8))
    {
        case 1: show_debug_message("packet ID 1"); break;
        case 2: show_debug_message("packet ID 2"); break;
        default: show_debug_message("unknown packet"); break;
    }
}

The code above will check for an incoming packet and get its data into a buffer (resizing if necessary) and reads from it.

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steam_net_packet_get_sender_id

Returns Steam ID of the user that sent the last received packet. Can be used in conjunction with steam_net_packet_send to send something back and for just telling the senders apart.

Syntax:

steam_net_packet_get_sender_id();

Returns:

int64

Example:

while(steam_net_packet_receive())
{
    var sender = steam_net_packet_get_sender_id();

    buffer_seek(outbuf, buffer_seek_start, 0);
    buffer_write(outbuf, buffer_u8, test_network_packet.ping);

    steam_net_packet_send(sender, outbuf);
}

The above code will show a code example.

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steam_net_packet_get_size

Returns the size of last received packet, in bytes.

Syntax:

steam_net_packet_get_size();

Returns:

real

Example:

while (steam_net_packet_receive())
{
    var size = steam_net_packet_size();
    show_debug_message("Received " + string(size) + " bytes.");
}

The code above will display the size of each incoming packet.

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steam_net_packet_receive

Attempts to get the next packet from Steam API and returns whether successfully done so. Other steam_net_ functions can then be used to get packet information/contents.

Syntax:

steam_net_packet_receive();

Returns:

bool

Example:

while (steam_net_packet_receive())
{
    // process the received packet
}

The code above will attempt to get the next packet from Steam API, would be used every step while in lobby or with less frequency otherwise.

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steam_net_packet_send

Sends a packet to the given endpoint, returns whether successful (as opposed to incorrect arguments/invalid ID). If no packet type is passed in then default value will be used, the default value can be set using the steam_net_packet_set_type function. Returns whether or not the packet was successfully sent.

Syntax:

steam_net_packet_send(user_id, buffer, size, packet_type)

Argument	Type	Description
user_id	int64	The target user to send the packet to
buffer	real	Buffer that contains the raw byte array for the packet data to send
size	real	The size of data to send (default -1, sends the entire buffer) ✴️ OPTIONAL
packet_type	PacketType	The type of packet to be used ✴️ OPTIONAL

Returns:

bool

Example:

var buf = buffer_create(16, buffer_grow, 1);
buffer_write(buf, buffer_string, "Hello!");
steam_net_packet_send(steam_id, buf, -1);
buffer_delete(buff);

The code sample will create a buffer and write to it, sending the total length of it to the given steam_id, the buffer is then deleted.

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steam_net_packet_set_type

Set the default connection protocol used when sending the data packets (using the steam_net_packet_send function). Returns whether or not the default protocol was successfully set.

Syntax:

steam_net_packet_set_type(protocol);

Argument	Type	Description
protocol	PacketType	The default connection protocol to be used

Returns:

bool

Example:

steam_net_packet_set_type(steam_net_packet_type_reliable)

The above code will set the current connection to use the steam_net_packet_type_reliable protocol to send data packages.

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steam_net_accept_p2p_session

Accepts a P2P session request from the specified user. Returns whether successful or not.

Syntax:

steam_net_accept_p2p_session(userID);

Argument	Type	Description
userID	int64	The User ID of the user that sent the initial packet to us.

Returns:

bool

Example:

if (isMyFriend(userID))
{
    steam_net_accept_p2p_session(userID);
}

The code above uses a custom implemented function that will check if a given userID is a friend and if it is it will accept the P2P session.

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steam_net_close_p2p_session

Closes a P2P session with the specified user. Returns whether successful or not. Steam will automatically close sessions after a period of inactivity, but you could also do it manually if you so desired.

Syntax:

steam_net_close_p2p_session(user_id)

Argument	Type	Description
user_id	int64	The user ID of the user to close the connection with.

Returns:

bool

Example:

if (global.chat_closed)
{
     steam_net_close_p2p_session(user_id)
}

The code above check to see if a global variable (chat_closed) is true and if so, it will close the P2P session.

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steam_net_set_auto_accept_p2p_sessions

Sets whether to auto-accept session requests coming from players in the same lobby. This is enabled by default for convenience. If you disable it, you will need to handle the async event when someone uses the steam_lobby_join_id function.

Syntax:

steam_net_set_auto_accept_p2p_sessions(enable);

Argument	Type	Description
enable	bool	disable/enable auto accept sessions

Returns:

Undefined

Triggers:

Asynchronous Steam Event (for each request, if disabled)

Key	Type	Description
type	string	The string value "lobby_join_requested"
lobby_id	int64	The lobby unique identifier
friend_id	int64	The friend unique identifier

Example:

steam_net_set_auto_accept_p2p_sessions(false);

The code above will disable the auto accept P2P sessions functionality meaning we should deal with the requests manually. In order to do so we need to use the Steam Async Event to catch the callback:

if (async_load[?"event_type"] == "lobby_join_requested")
{
    steam_net_accept_p2p_session(async_load[?"friend_id"]);
}

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PacketType

These constants specify the type of a steam packet and should be used with the function steam_net_packet_set_type.

Packet Type Constant	Description
steam_net_packet_type_unreliable	Equivalent to UDP the data may or may not be delivered, will not be resent automatically.
steam_net_packet_type_unreliable_nodelay	Similar to "unreliable" type, but always sent instantly (as soon as function is called). Intended for things like streaming voice data, where you want lowest latency possible and only care about the current data.
steam_net_packet_type_reliable	Equivalent to TCP, the data is warranted to be delivered in order and intact.
steam_net_packet_type_reliable_buffer	Similar to "reliable" type, but utilizes Nagle's algorithm to reduce the number of packets at cost of potential delay while the data accumulates until the sending threshold.

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