Network library

UDP transport, packet and message framing, sequence tracking and connection management (lib/Network). More...

Classes
class	Connection
	State the server keeps for one connected client. More...
struct	NetworkMetrics
	Traffic and latency counters of a network endpoint. More...
struct	HandshakeHeader
	Header of the datagrams exchanged before a connection exists. More...
struct	MessageHeader
	Header placed in front of every message inside a connected packet. More...
struct	ParsedMessage
	Message extracted from a connected packet. More...
class	MessageParser
	Splits the body of a connected packet into messages. More...
struct	PacketHeader
	Header that starts every packet sent on an open connection. More...
class	PacketReader
	Bounds checked reader of big-endian values over a byte buffer. More...
class	PacketWriter
	Growable buffer of big-endian values, capped at MAX_PAYLOAD_SIZE. More...
struct	PingMessage
	Payload of a Ping message, 4 bytes, sent by a client to measure latency. More...
struct	PongMessage
	Payload of a Pong message, 4 bytes, sent by the server in answer to a Ping. More...
class	NetworkServer
	UDP server that runs the handshake, tracks connections and dispatches messages. More...
class	PacketTracker
	Generates outgoing sequence numbers and tracks received ones. More...
class	UdpTransport
	Asynchronous UDP socket wrapper used by the server. More...

Typedefs
using	MessageId = std::uint16_t
	Numeric identifier of a message type.

Enumerations
enum class	HandshakeType : std::uint8_t { HandshakeType::Hello = 1 , HandshakeType::Welcome = 2 , HandshakeType::Rejected = 3 }
	Kind of handshake datagram. More...
enum class	PacketReceiveRes { PacketReceiveRes::New , PacketReceiveRes::Dup , PacketReceiveRes::Out , PacketReceiveRes::TooOld }
	Classification of a received packet sequence number. More...

Functions
void	updateRttMetrics (NetworkMetrics &metrics, float newRtt)
	Adds a round trip time sample and updates smoothing and jitter.
void	updatePacketMetrics (NetworkMetrics &metrics)
	Recomputes the packet loss percentage.
void	onPacketSend (NetworkMetrics &metrics, std::size_t packetSize)
	Counts a sent datagram.
void	onPacketReceived (NetworkMetrics &metrics, std::size_t packetSize)
	Counts a received datagram.
void	onPacketDuplicated (NetworkMetrics &metrics)
	Counts a duplicated datagram.
void	onPacketOut (NetworkMetrics &metrics)
	Counts a datagram received out of order.
void	onRetransmission (NetworkMetrics &metrics)
	Counts a retransmitted datagram.

Variables
constexpr std::size_t	MAX_PACKET_SIZE = 576
	Largest IPv4 datagram every host is required to accept, in bytes.
constexpr std::size_t	IP_HEADER_SIZE = 20
	Size of an IPv4 header without options, in bytes.
constexpr std::size_t	UDP_HEADER_SIZE = 8
	Size of a UDP header, in bytes.
constexpr std::size_t	MAX_PAYLOAD_SIZE
	Largest UDP payload sent or accepted by the network layer, in bytes.
constexpr std::size_t	PACKET_HEADER_SIZE = 16
	Size of the PacketHeader that starts every connected packet, in bytes.
constexpr std::size_t	MAX_MESSAGE_SIZE
	Room left for messages after the packet header, in bytes.
constexpr std::uint32_t	MAGIC = 0x52545950
	Magic number that starts every handshake datagram, "RTYP" in ASCII.
constexpr std::uint8_t	VERSION = 1
	Protocol version announced and expected during the handshake.
constexpr MessageId	systemMessage::Ping = 0x03
	Latency probe sent by a client.
constexpr MessageId	systemMessage::Disconnect = 0x04
	Client closes its connection.
constexpr MessageId	systemMessage::Pong = 0x86
	Server answer to a Ping.

Detailed Description

UDP transport, packet and message framing, sequence tracking and connection management (lib/Network).

See Networking for an overview.

Enumeration Type Documentation

HandshakeType

enum class HandshakeType : std::uint8_t

strong

Kind of handshake datagram.

Enumerator
Hello	Client asks the server to open a connection.
Welcome	Server accepts the client and gives its connection id.
Rejected	Server refuses the connection.

PacketReceiveRes

enum class PacketReceiveRes

strong

Classification of a received packet sequence number.

Enumerator
New	Newer than every packet received so far.
Dup	Already received.
Out	Older than the latest one but inside the 32 packet window.
TooOld	Older than the 32 packet window.

Function Documentation

updateRttMetrics()

void updateRttMetrics	(	NetworkMetrics &	metrics,
		float	newRtt )

Adds a round trip time sample and updates smoothing and jitter.

Parameters

metrics	Counters to update.
newRtt	New round trip time sample.

updatePacketMetrics()

void updatePacketMetrics

(

NetworkMetrics &

metrics

)

Recomputes the packet loss percentage.

Parameters

metrics

Counters to update.

onPacketSend()

void onPacketSend	(	NetworkMetrics &	metrics,
		std::size_t	packetSize )

Counts a sent datagram.

Parameters

metrics	Counters to update.
packetSize	Size of the datagram in bytes.

onPacketReceived()

void onPacketReceived	(	NetworkMetrics &	metrics,
		std::size_t	packetSize )

Counts a received datagram.

Parameters

metrics	Counters to update.
packetSize	Size of the datagram in bytes.

onPacketDuplicated()

void onPacketDuplicated

(

NetworkMetrics &

metrics

)

Counts a duplicated datagram.

Parameters

metrics

Counters to update.

onPacketOut()

void onPacketOut

(

NetworkMetrics &

metrics

)

Counts a datagram received out of order.

Parameters

metrics

Counters to update.

onRetransmission()

void onRetransmission

(

NetworkMetrics &

metrics

)

Counts a retransmitted datagram.

Parameters

metrics

Counters to update.

Variable Documentation

MAX_PAYLOAD_SIZE

std::size_t MAX_PAYLOAD_SIZE

inlineconstexpr

Initial value:

=
    MAX_PACKET_SIZE - IP_HEADER_SIZE - UDP_HEADER_SIZE

Largest UDP payload sent or accepted by the network layer, in bytes.

MAX_MESSAGE_SIZE

std::size_t MAX_MESSAGE_SIZE

inlineconstexpr

Initial value:

=
    MAX_PAYLOAD_SIZE - PACKET_HEADER_SIZE

Room left for messages after the packet header, in bytes.