Add vnet to SettingEngine

Also add simple example to show usage

Resolves #778

examples/vnet/README.md

@@ -0,0 +1,15 @@
+# vnet
+vnet is the virtual network layer for Pion. This allows developers to simulate issues that cause issues
+with production WebRTC deployments.
+
+See the full documentation for vnet [here](https://github.com/pion/transport/tree/master/vnet#vnet)
+
+## What can vnet do
+* Simulate different network topologies. Assert when a STUN/TURN server is actually needed.
+* Simulate packet loss, jitter, re-ordering. See how your application performs under adverse conditions.
+* Measure the total bandwidth used. Determine the total cost of running your application.
+* More! We would love to continue extending this to support everyones needs.
+
+## Instructions
+Each directory contains a single `main.go` that aims to demonstrate a single feature of vnet.
+They can all be run directly, and require no additional setup.

examples/vnet/show-network-usage/main.go

@@ -0,0 +1,78 @@
+package main
+
+import (
+	"time"
+
+	"github.com/pion/logging"
+	"github.com/pion/transport/vnet"
+	"github.com/pion/webrtc/v2"
+)
+
+func main() {
+	wan, err := vnet.NewRouter(&vnet.RouterConfig{
+		CIDR:          "1.2.3.0/24",
+		LoggerFactory: logging.NewDefaultLoggerFactory(),
+	})
+	panicIfError(err)
+
+	offerVNet := vnet.NewNet(&vnet.NetConfig{})
+	panicIfError(wan.AddNet(offerVNet))
+
+	offerSettingEngine := webrtc.SettingEngine{}
+	offerSettingEngine.SetVNet(offerVNet)
+	offerAPI := webrtc.NewAPI(webrtc.WithSettingEngine(offerSettingEngine))
+
+	answerVNet := vnet.NewNet(&vnet.NetConfig{})
+	panicIfError(wan.AddNet(answerVNet))
+
+	answerSettingEngine := webrtc.SettingEngine{}
+	answerSettingEngine.SetVNet(answerVNet)
+	answerAPI := webrtc.NewAPI(webrtc.WithSettingEngine(answerSettingEngine))
+
+	panicIfError(wan.Start())
+
+	offerPeerConnection, err := offerAPI.NewPeerConnection(webrtc.Configuration{})
+	panicIfError(err)
+
+	answerPeerConnection, err := answerAPI.NewPeerConnection(webrtc.Configuration{})
+	panicIfError(err)
+
+	offerDataChannel, err := offerPeerConnection.CreateDataChannel("label", nil)
+	panicIfError(err)
+
+	msgSendLoop := func(dc *webrtc.DataChannel) {
+		for {
+			time.Sleep(500 * time.Millisecond)
+			panicIfError(dc.SendText("My DataChannel Message"))
+		}
+
+	}
+
+	offerDataChannel.OnOpen(func() {
+		msgSendLoop(offerDataChannel)
+	})
+
+	answerPeerConnection.OnDataChannel(func(answerDataChannel *webrtc.DataChannel) {
+		answerDataChannel.OnOpen(func() {
+			msgSendLoop(answerDataChannel)
+		})
+	})
+
+	offer, err := offerPeerConnection.CreateOffer(nil)
+	panicIfError(err)
+	panicIfError(offerPeerConnection.SetLocalDescription(offer))
+	panicIfError(answerPeerConnection.SetRemoteDescription(offer))
+
+	answer, err := answerPeerConnection.CreateAnswer(nil)
+	panicIfError(err)
+	panicIfError(answerPeerConnection.SetLocalDescription(answer))
+	panicIfError(offerPeerConnection.SetRemoteDescription(answer))
+
+	select {}
+}
+
+func panicIfError(err error) {
+	if err != nil {
+		panic(err)
+	}
+}

icegatherer.go

@@ -96,6 +96,7 @@ func (g *ICEGatherer) createAgent() error {
 		InterfaceFilter:           g.api.settingEngine.candidates.InterfaceFilter,
 		NAT1To1IPs:                g.api.settingEngine.candidates.NAT1To1IPs,
 		NAT1To1IPCandidateType:    nat1To1CandiTyp,
+		Net:                       g.api.settingEngine.vnet,
 	}
 
 	requestedNetworkTypes := g.api.settingEngine.candidates.ICENetworkTypes

settingengine.go

@@ -8,6 +8,7 @@ import (
 
 	"github.com/pion/ice"
 	"github.com/pion/logging"
+	"github.com/pion/transport/vnet"
 )
 
 // SettingEngine allows influencing behavior in ways that are not
@@ -39,6 +40,7 @@ type SettingEngine struct {
 		NAT1To1IPCandidateType ICECandidateType
 	}
 	answeringDTLSRole DTLSRole
+	vnet              *vnet.Net
 	LoggerFactory     logging.LoggerFactory
 }
 
@@ -163,3 +165,12 @@ func (e *SettingEngine) SetAnsweringDTLSRole(role DTLSRole) error {
 	e.answeringDTLSRole = role
 	return nil
 }
+
+// SetVNet sets the VNet instance that is passed to pion/ice
+//
+// VNet is a virtual network layer for Pion, allowing users to simulate
+// different topologies, latency, loss and jitter. This can be useful for
+// learning WebRTC concepts or testing your application in a lab environment
+func (e *SettingEngine) SetVNet(vnet *vnet.Net) {
+	e.vnet = vnet
+}