lossy

avec perte

Package Go pour simuler la bande passante, la latence et la perte de paquets pour les interfaces net.PacketConn et net.Conn.

Son utilisation principale est de tester la robustesse des applications et des protocoles réseau exécutés sur des protocoles de transport peu fiables tels que UDP ou IP. Autre avantage, il peut également être utilisé comme limiteur de bande passante sortante.

avec perte ne modifie que le côté écriture de la connexion, le côté lecture est conservé tel quel.

Exemple

 package main

import (
	"fmt"
	"github.com/cevatbarisyilmaz/lossy"
	"log"
	"math/rand"
	"net"
	"time"
)

const packetSize = 64

func main () {
	// Create two connection endpoints over UDP
	packetConn , conn := createConnections ()

	// Create a lossy packet connection
	bandwidth := 1048 // 8 Kbit/s
	minLatency := 100 * time . Millisecond
	maxLatency := time . Second
	packetLossRate := 0.33
	headerOverhead := lossy . UDPv4MinHeaderOverhead
	lossyPacketConn := lossy . NewPacketConn ( packetConn , bandwidth , minLatency , maxLatency , packetLossRate , headerOverhead )

	// Write some packets via lossy
	var bytesWritten int
	const packetCount = 32
	go func () {
		for i := 0 ; i < packetCount ; i ++ {
			packet := createPacket ()
			_ , err := lossyPacketConn . WriteTo ( packet , conn . LocalAddr ())
			if err != nil {
				log . Fatal ( err )
			}
			bytesWritten += len ( packet ) + headerOverhead
		}
		fmt . Println ( "Sent" , packetCount , "packets with total size of" , bytesWritten , "bytes" )
		baseTransmissionDuration := time . Duration ( float64 ( bytesWritten * int ( time . Second )) / float64 ( bandwidth ))
		earliestCompletion := baseTransmissionDuration + minLatency
		latestCompletion := baseTransmissionDuration + maxLatency
		fmt . Println ( "Expected transmission duration is between" , earliestCompletion , "and" , latestCompletion )
	}()

	// Read packets at the other side
	const timeout = 3 * time . Second
	var packets , bytesRead int
	startTime := time . Now ()
	for {
		_ = conn . SetReadDeadline ( time . Now (). Add ( timeout ))
		buffer := make ([] byte , packetSize )
		n , err := conn . Read ( buffer )
		if err != nil {
			break
		}
		bytesRead += n + headerOverhead
		packets ++
	}
	dur := time . Now (). Sub ( startTime ) - timeout
	fmt . Println ( "Received" , packets , "packets with total size of" , bytesRead , "bytes in" , dur )

	// Close the connections
	_ = lossyPacketConn . Close ()
	_ = conn . Close ()
}

func createConnections () (net. PacketConn , net. Conn ) {
	packetConn , err := net . ListenUDP ( "udp" , & net. UDPAddr {
		IP :   net . IPv4 ( 127 , 0 , 0 , 1 ),
		Port : 0 ,
	})
	if err != nil {
		log . Fatal ( err )
	}
	conn , err := net . DialUDP ( "udp" , nil , packetConn . LocalAddr ().( * net. UDPAddr ))
	if err != nil {
		log . Fatal ( err )
	}
	return packetConn , conn
}

func createPacket () [] byte {
	packet := make ([] byte , packetSize )
	rand . Read ( packet )
	return packet
}

Sortir

 Sent 32 packets with total size of 2944 bytes
Expected transmission duration is between 2.909160305s and 3.809160305s
Received 23 packets with total size of 2116 bytes in 3.2507523s