transport

Documentation

Overview

Package transport provides a listener and sender channel for unicast and multicast UDP IPv4 short message chat protocol with a pre shared key, forward error correction facilities with a nice friendly declaration syntax

Index

• Constants
• Variables
• func DecryptMessage(creator string, ciph cipher.AEAD, data []byte) (msg []byte, e error)
• func EncryptMessage(creator string, ciph cipher.AEAD, magic []byte, nonce, data []byte) (msg []byte, e error)
• func GetNonce(ciph cipher.AEAD) (nonce []byte, e error)
• func GetShards(data []byte) (shards [][]byte)
• func Handle(address string, channel *Channel, handlers Handlers, maxDatagramSize int, ...)
• func Listen(address string, channel *Channel, maxDatagramSize int, handlers Handlers, ...) (conn *net.UDPConn, e error)
• func ListenBroadcast(port int, channel *Channel, maxDatagramSize int, handlers Handlers, quit qu.C) (conn *net.UDPConn, e error)
• func NewBroadcaster(port int, maxDatagramSize int) (conn *net.UDPConn, e error)
• func NewSender(address string, maxDatagramSize int) (conn *net.UDPConn, e error)
• func PrevCallers() (out string)
• type Channel
  • func NewBroadcastChannel(creator string, ctx interface{}, key []byte, port int, maxDatagramSize int, ...) (channel *Channel, e error)
  • func NewUnicastChannel(creator string, ctx interface{}, key []byte, sender, receiver string, ...) (channel *Channel, e error)
  • func (c *Channel) Close() (e error)
  • func (c *Channel) Send(magic []byte, nonce []byte, data []byte) (n int, e error)
  • func (c *Channel) SendMany(magic []byte, b [][]byte) (e error)
  • func (c *Channel) SetDestination(dst string) (e error)
• type Connection
  • func (c *Connection) CreateShards(b, magic []byte) (shards [][]byte, e error)
  • func (c *Connection) Listen(handlers HandleFunc, ifc interface{}, lastSent *time.Time, firstSender *string) (e error)
  • func (c *Connection) Send(b, magic []byte) (e error)
  • func (c *Connection) SendShards(shards [][]byte) (e error)
  • func (c *Connection) SendShardsTo(shards [][]byte, addr *net.UDPAddr) (e error)
  • func (c *Connection) SendTo(addr *net.UDPAddr, b, magic []byte) (e error)
  • func (c *Connection) SetSendConn(ad string) (e error)
• type HandleFunc
• type HandlerFunc
• type Handlers
• type MsgBuffer

Constants

const (
	UDPMulticastAddress = "224.0.0.1"

	DefaultPort = 11049
)

Variables

var DefaultIP = net.IPv4(224, 0, 0, 1)

var F, E, W, I, D, T log.LevelPrinter = log.GetLogPrinterSet(subsystem)

var MulticastAddress = &net.UDPAddr{IP: DefaultIP, Port: DefaultPort}

Functions

func DecryptMessage

func DecryptMessage(creator string, ciph cipher.AEAD, data []byte) (msg []byte, e error)

DecryptMessage attempts to decode the received message

func EncryptMessage

func EncryptMessage(creator string, ciph cipher.AEAD, magic []byte, nonce, data []byte) (msg []byte, e error)

EncryptMessage encrypts a message, if the nonce is given it uses that otherwise it generates a new one. If there is no cipher this just returns a message with the given magic prepended.

func GetNonce

func GetNonce(ciph cipher.AEAD) (nonce []byte, e error)

GetNonce reads from a cryptographicallly secure random number source

func GetShards

func GetShards(data []byte) (shards [][]byte)

GetShards returns a buffer iterator to feed to Channel.SendMany containing fec encoded shards built from the provided buffer

func Handle

func Handle(
	address string, channel *Channel,
	handlers Handlers, maxDatagramSize int, quit qu.C,
)

Handle listens for messages, decodes them, aggregates them, recovers the data from the reed solomon fec shards received and invokes the handler provided matching the magic on the complete received messages

func Listen

func Listen(
	address string, channel *Channel, maxDatagramSize int, handlers Handlers,
	quit qu.C,
) (conn *net.UDPConn, e error)

Listen binds to the UDP Address and port given and writes packets received from that Address to a buffer which is passed to a handler

func ListenBroadcast

func ListenBroadcast(
	port int,
	channel *Channel,
	maxDatagramSize int,
	handlers Handlers,
	quit qu.C,
) (conn *net.UDPConn, e error)

ListenBroadcast binds to the UDP Address and port given and writes packets received from that Address to a buffer which is passed to a handler

func NewBroadcaster

func NewBroadcaster(port int, maxDatagramSize int) (
	conn *net.UDPConn, e error,
)

NewBroadcaster creates a new UDP multicast connection on which to broadcast

func NewSender

func NewSender(address string, maxDatagramSize int) (
	conn *net.UDPConn, e error,
)

NewSender creates a new UDP connection to a specified address

func PrevCallers

func PrevCallers() (out string)

Types

type Channel

type Channel struct {
	Ready qu.C

	Creator string

	MaxDatagramSize int

	Receiver *net.UDPConn

	Sender *net.UDPConn
	// contains filtered or unexported fields
}

func NewBroadcastChannel

func NewBroadcastChannel(
	creator string, ctx interface{}, key []byte, port int, maxDatagramSize int,
	handlers Handlers,
	quit qu.C,
) (channel *Channel, e error)

NewBroadcastChannel returns a broadcaster and listener with a given handler on a multicast address and specified port. The handlers define the messages that will be processed and any other messages are ignored

func NewUnicastChannel

func NewUnicastChannel(
	creator string, ctx interface{}, key []byte, sender, receiver string,
	maxDatagramSize int,
	handlers Handlers, quit qu.C,
) (channel *Channel, e error)

NewUnicastChannel sets up a listener and sender for a specified destination

func (*Channel) Close

func (c *Channel) Close() (e error)

Close the multicast

func (*Channel) Send

func (c *Channel) Send(magic []byte, nonce []byte, data []byte) (
	n int, e error,
)

Send fires off some data through the configured multicast's outbound.

func (*Channel) SendMany

func (c *Channel) SendMany(magic []byte, b [][]byte) (e error)

SendMany sends a BufIter of shards as produced by GetShards

func (*Channel) SetDestination

func (c *Channel) SetDestination(dst string) (e error)

SetDestination changes the address the outbound connection of a multicast directs to

type Connection

type Connection struct {
	SendConn net.Conn
	// contains filtered or unexported fields
}

Connection is the state and working memory references for a simple reliable UDP lan transport, encrypted by a GCM AES cipher, with the simple protocol of sending out 9 packets containing encrypted FEC shards containing a slice of bytes.

This protocol probably won't work well outside of a multicast lan in adverse conditions but it is designed for local network control systems todo: it is if the updated fec segmenting code is put in

func (*Connection) CreateShards

func (c *Connection) CreateShards(b, magic []byte) (
	shards [][]byte,
	e error,
)

CreateShards takes a slice of bites and generates 3

func (*Connection) Listen

func (c *Connection) Listen(handlers HandleFunc, ifc interface{},
	lastSent *time.Time, firstSender *string,
) (e error)

Listen runs a goroutine that collects and attempts to decode the FEC shards once it has enough intact pieces

func (*Connection) Send

func (c *Connection) Send(b, magic []byte) (e error)

func (*Connection) SendShards

func (c *Connection) SendShards(shards [][]byte) (e error)

func (*Connection) SendShardsTo

func (c *Connection) SendShardsTo(shards [][]byte, addr *net.UDPAddr,
) (e error)

func (*Connection) SendTo

func (c *Connection) SendTo(addr *net.UDPAddr, b, magic []byte) (e error)

func (*Connection) SetSendConn

func (c *Connection) SetSendConn(ad string) (e error)

SetSendConn sets up an outbound connection

type HandleFunc

type HandleFunc map[string]func(ctx interface{}) func(b []byte) (e error)

HandleFunc is a map of handlers for working on received, decoded packets

type HandlerFunc

type HandlerFunc func(
	ctx interface{}, src net.Addr, dst string, b []byte,
) (e error)

HandlerFunc is a function that is used to process a received message

type Handlers

type Handlers map[string]HandlerFunc

type MsgBuffer

type MsgBuffer struct {
	Buffers [][]byte
	First   time.Time
	Decoded bool
	Source  net.Addr
}