Integrate Limited Relays

config/config.go

@@ -3,6 +3,7 @@ package config
 import (
 	"context"
 	"crypto/rand"
+	"errors"
 	"fmt"
 	"time"
 
@@ -24,8 +25,7 @@ import (
 
 	autonat "github.com/libp2p/go-libp2p-autonat"
 	blankhost "github.com/libp2p/go-libp2p-blankhost"
-	circuit "github.com/libp2p/go-libp2p-circuit"
-	discovery "github.com/libp2p/go-libp2p-discovery"
+	circuitv2 "github.com/libp2p/go-libp2p-circuit/v2/client"
 	swarm "github.com/libp2p/go-libp2p-swarm"
 	tptu "github.com/libp2p/go-libp2p-transport-upgrader"
 
@@ -74,7 +74,6 @@ type Config struct {
 
 	RelayCustom bool
 	Relay       bool
-	RelayOpts   []circuit.RelayOpt
 
 	ListenAddrs     []ma.Multiaddr
 	AddrsFactory    bhost.AddrsFactory
@@ -92,6 +91,8 @@ type Config struct {
 	EnableAutoRelay bool
 	AutoNATConfig
 	StaticRelays []peer.AddrInfo
+
+	EnableHolePunching bool
 }
 
 func (cfg *Config) makeSwarm(ctx context.Context) (*swarm.Swarm, error) {
@@ -166,7 +167,7 @@ func (cfg *Config) addTransports(ctx context.Context, h host.Host) (err error) {
 	}
 
 	if cfg.Relay {
-		err := circuit.AddRelayTransport(ctx, h, upgrader, cfg.RelayOpts...)
+		err := circuitv2.AddTransport(ctx, h, upgrader)
 		if err != nil {
 			h.Close()
 			return err
@@ -185,12 +186,17 @@ func (cfg *Config) NewNode(ctx context.Context) (host.Host, error) {
 		return nil, err
 	}
 
+	if cfg.EnableHolePunching && !cfg.Relay {
+		return nil, errors.New("cannot enable hole punching; relay is not enabled")
+	}
+
 	h, err := bhost.NewHost(ctx, swrm, &bhost.HostOpts{
-		ConnManager:  cfg.ConnManager,
-		AddrsFactory: cfg.AddrsFactory,
-		NATManager:   cfg.NATManager,
-		EnablePing:   !cfg.DisablePing,
-		UserAgent:    cfg.UserAgent,
+		ConnManager:        cfg.ConnManager,
+		AddrsFactory:       cfg.AddrsFactory,
+		NATManager:         cfg.NATManager,
+		EnablePing:         !cfg.DisablePing,
+		UserAgent:          cfg.UserAgent,
+		EnableHolePunching: cfg.EnableHolePunching,
 	})
 
 	if err != nil {
@@ -230,7 +236,7 @@ func (cfg *Config) NewNode(ctx context.Context) (host.Host, error) {
 		return nil, err
 	}
 
-	// Configure routing and autorelay
+	// Configure routing
 	var router routing.PeerRouting
 	if cfg.Routing != nil {
 		router, err = cfg.Routing(h)
@@ -240,6 +246,7 @@ func (cfg *Config) NewNode(ctx context.Context) (host.Host, error) {
 		}
 	}
 
+	// Configure AutoRelay
 	// Note: h.AddrsFactory may be changed by AutoRelay, but non-relay version is
 	// used by AutoNAT below.
 	addrF := h.AddrsFactory
@@ -249,36 +256,10 @@ func (cfg *Config) NewNode(ctx context.Context) (host.Host, error) {
 			return nil, fmt.Errorf("cannot enable autorelay; relay is not enabled")
 		}
 
-		hop := false
-		for _, opt := range cfg.RelayOpts {
-			if opt == circuit.OptHop {
-				hop = true
-				break
-			}
-		}
-
-		if !hop && len(cfg.StaticRelays) > 0 {
+		if len(cfg.StaticRelays) > 0 {
 			_ = relay.NewAutoRelay(ctx, h, nil, router, cfg.StaticRelays)
 		} else {
-			if router == nil {
-				h.Close()
-				return nil, fmt.Errorf("cannot enable autorelay; no routing for discovery")
-			}
-
-			crouter, ok := router.(routing.ContentRouting)
-			if !ok {
-				h.Close()
-				return nil, fmt.Errorf("cannot enable autorelay; no suitable routing for discovery")
-			}
-
-			discovery := discovery.NewRoutingDiscovery(crouter)
-
-			if hop {
-				// advertise ourselves
-				relay.Advertise(ctx, discovery)
-			} else {
-				_ = relay.NewAutoRelay(ctx, h, discovery, router, cfg.StaticRelays)
-			}
+			return nil, errors.New("need to configure v2 Relays to use for AutoRelay")
 		}
 	}
 

go.mod

@@ -11,13 +11,14 @@ require (
 	github.com/ipfs/go-log v1.0.4
 	github.com/jbenet/go-cienv v0.1.0
 	github.com/jbenet/goprocess v0.1.4
+	github.com/jpillora/backoff v1.0.0
 	github.com/libp2p/go-addr-util v0.0.2
 	github.com/libp2p/go-conn-security-multistream v0.2.1
 	github.com/libp2p/go-eventbus v0.2.1
 	github.com/libp2p/go-libp2p-autonat v0.4.0
 	github.com/libp2p/go-libp2p-blankhost v0.2.0
-	github.com/libp2p/go-libp2p-circuit v0.4.0
-	github.com/libp2p/go-libp2p-core v0.8.2
+	github.com/libp2p/go-libp2p-circuit v0.4.1-0.20210219221135-acf512620b1a
+	github.com/libp2p/go-libp2p-core v0.8.4
 	github.com/libp2p/go-libp2p-discovery v0.5.0
 	github.com/libp2p/go-libp2p-loggables v0.1.0
 	github.com/libp2p/go-libp2p-mplex v0.4.1

go.sum

@@ -34,6 +34,7 @@ github.com/btcsuite/winsvc v1.0.0/go.mod h1:jsenWakMcC0zFBFurPLEAyrnc/teJEM1O46f
 github.com/buger/jsonparser v0.0.0-20181115193947-bf1c66bbce23/go.mod h1:bbYlZJ7hK1yFx9hf58LP0zeX7UjIGs20ufpu3evjr+s=
 github.com/census-instrumentation/opencensus-proto v0.2.1/go.mod h1:f6KPmirojxKA12rnyqOA5BBL4O983OfeGPqjHWSTneU=
 github.com/cespare/xxhash v1.1.0/go.mod h1:XrSqR1VqqWfGrhpAt58auRo0WTKS1nRRg3ghfAqPWnc=
+github.com/cheekybits/genny v1.0.0 h1:uGGa4nei+j20rOSeDeP5Of12XVm7TGUd4dJA9RDitfE=
 github.com/cheekybits/genny v1.0.0/go.mod h1:+tQajlRqAUrPI7DOSpB0XAqZYtQakVtB7wXkRAgjxjQ=
 github.com/client9/misspell v0.3.4/go.mod h1:qj6jICC3Q7zFZvVWo7KLAzC3yx5G7kyvSDkc90ppPyw=
 github.com/cncf/udpa/go v0.0.0-20191209042840-269d4d468f6f/go.mod h1:M8M6+tZqaGXZJjfX53e64911xZQV5JYwmTeXPW+k8Sc=
@@ -201,6 +202,8 @@ github.com/jbenet/goprocess v0.1.4/go.mod h1:5yspPrukOVuOLORacaBi858NqyClJPQxYZl
 github.com/jellevandenhooff/dkim v0.0.0-20150330215556-f50fe3d243e1/go.mod h1:E0B/fFc00Y+Rasa88328GlI/XbtyysCtTHZS8h7IrBU=
 github.com/jessevdk/go-flags v0.0.0-20141203071132-1679536dcc89/go.mod h1:4FA24M0QyGHXBuZZK/XkWh8h0e1EYbRYJSGM75WSRxI=
 github.com/jessevdk/go-flags v1.4.0/go.mod h1:4FA24M0QyGHXBuZZK/XkWh8h0e1EYbRYJSGM75WSRxI=
+github.com/jpillora/backoff v1.0.0 h1:uvFg412JmmHBHw7iwprIxkPMI+sGQ4kzOWsMeHnm2EA=
+github.com/jpillora/backoff v1.0.0/go.mod h1:J/6gKK9jxlEcS3zixgDgUAsiuZ7yrSoa/FX5e0EB2j4=
 github.com/jrick/logrotate v1.0.0/go.mod h1:LNinyqDIJnpAur+b8yyulnQw/wDuN1+BYKlTRt3OuAQ=
 github.com/json-iterator/go v1.1.6/go.mod h1:+SdeFBvtyEkXs7REEP0seUULqWtbJapLOCVDaaPEHmU=
 github.com/jstemmer/go-junit-report v0.0.0-20190106144839-af01ea7f8024/go.mod h1:6v2b51hI/fHJwM22ozAgKL4VKDeJcHhJFhtBdhmNjmU=
@@ -226,6 +229,8 @@ github.com/libp2p/go-addr-util v0.0.2/go.mod h1:Ecd6Fb3yIuLzq4bD7VcywcVSBtefcAwn
 github.com/libp2p/go-buffer-pool v0.0.1/go.mod h1:xtyIz9PMobb13WaxR6Zo1Pd1zXJKYg0a8KiIvDp3TzQ=
 github.com/libp2p/go-buffer-pool v0.0.2 h1:QNK2iAFa8gjAe1SPz6mHSMuCcjs+X1wlHzeOSqcmlfs=
 github.com/libp2p/go-buffer-pool v0.0.2/go.mod h1:MvaB6xw5vOrDl8rYZGLFdKAuk/hRoRZd1Vi32+RXyFM=
+github.com/libp2p/go-cidranger v1.1.0 h1:ewPN8EZ0dd1LSnrtuwd4709PXVcITVeuwbag38yPW7c=
+github.com/libp2p/go-cidranger v1.1.0/go.mod h1:KWZTfSr+r9qEo9OkI9/SIEeAtw+NNoU0dXIXt15Okic=
 github.com/libp2p/go-conn-security-multistream v0.1.0/go.mod h1:aw6eD7LOsHEX7+2hJkDxw1MteijaVcI+/eP2/x3J1xc=
 github.com/libp2p/go-conn-security-multistream v0.2.0 h1:uNiDjS58vrvJTg9jO6bySd1rMKejieG7v45ekqHbZ1M=
 github.com/libp2p/go-conn-security-multistream v0.2.0/go.mod h1:hZN4MjlNetKD3Rq5Jb/P5ohUnFLNzEAR4DLSzpn2QLU=
@@ -241,6 +246,8 @@ github.com/libp2p/go-libp2p v0.6.1/go.mod h1:CTFnWXogryAHjXAKEbOf1OWY+VeAP3lDMZk
 github.com/libp2p/go-libp2p v0.7.0/go.mod h1:hZJf8txWeCduQRDC/WSqBGMxaTHCOYHt2xSU1ivxn0k=
 github.com/libp2p/go-libp2p v0.7.4/go.mod h1:oXsBlTLF1q7pxr+9w6lqzS1ILpyHsaBPniVO7zIHGMw=
 github.com/libp2p/go-libp2p v0.8.1/go.mod h1:QRNH9pwdbEBpx5DTJYg+qxcVaDMAz3Ee/qDKwXujH5o=
+github.com/libp2p/go-libp2p-asn-util v0.0.0-20210211060025-0db24c10d3bd h1:4+wRQ07VJe0ogkb74jFJwhiPuuSbSY1zSUl+tFlNbpg=
+github.com/libp2p/go-libp2p-asn-util v0.0.0-20210211060025-0db24c10d3bd/go.mod h1:nRMRTab+kZuk0LnKZpxhOVH/ndsdr2Nr//Zltc/vwgo=
 github.com/libp2p/go-libp2p-autonat v0.1.1/go.mod h1:OXqkeGOY2xJVWKAGV2inNF5aKN/djNA3fdpCWloIudE=
 github.com/libp2p/go-libp2p-autonat v0.2.0/go.mod h1:DX+9teU4pEEoZUqR1PiMlqliONQdNbfzE1C718tcViI=
 github.com/libp2p/go-libp2p-autonat v0.2.1/go.mod h1:MWtAhV5Ko1l6QBsHQNSuM6b1sRkXrpk0/LqCr+vCVxI=
@@ -252,9 +259,10 @@ github.com/libp2p/go-libp2p-blankhost v0.1.4/go.mod h1:oJF0saYsAXQCSfDq254GMNmLN
 github.com/libp2p/go-libp2p-blankhost v0.2.0 h1:3EsGAi0CBGcZ33GwRuXEYJLLPoVWyXJ1bcJzAJjINkk=
 github.com/libp2p/go-libp2p-blankhost v0.2.0/go.mod h1:eduNKXGTioTuQAUcZ5epXi9vMl+t4d8ugUBRQ4SqaNQ=
 github.com/libp2p/go-libp2p-circuit v0.1.4/go.mod h1:CY67BrEjKNDhdTk8UgBX1Y/H5c3xkAcs3gnksxY7osU=
+github.com/libp2p/go-libp2p-circuit v0.2.1 h1:BDiBcQxX/ZJJ/yDl3sqZt1bjj4PkZCEi7IEpwxXr13k=
 github.com/libp2p/go-libp2p-circuit v0.2.1/go.mod h1:BXPwYDN5A8z4OEY9sOfr2DUQMLQvKt/6oku45YUmjIo=
-github.com/libp2p/go-libp2p-circuit v0.4.0 h1:eqQ3sEYkGTtybWgr6JLqJY6QLtPWRErvFjFDfAOO1wc=
-github.com/libp2p/go-libp2p-circuit v0.4.0/go.mod h1:t/ktoFIUzM6uLQ+o1G6NuBl2ANhBKN9Bc8jRIk31MoA=
+github.com/libp2p/go-libp2p-circuit v0.4.1-0.20210219221135-acf512620b1a h1:o3lSbSYBFaiM6E7LSL3plAnsZlzS8w0rpcLccTwwtHc=
+github.com/libp2p/go-libp2p-circuit v0.4.1-0.20210219221135-acf512620b1a/go.mod h1:YeUzEy50jG3sJMhAUxj+VoAqcdLqWGmJ70QhcHb6r6E=
 github.com/libp2p/go-libp2p-core v0.0.1/go.mod h1:g/VxnTZ/1ygHxH3dKok7Vno1VfpvGcGip57wjTU4fco=
 github.com/libp2p/go-libp2p-core v0.0.4/go.mod h1:jyuCQP356gzfCFtRKyvAbNkyeuxb7OlyhWZ3nls5d2I=
 github.com/libp2p/go-libp2p-core v0.2.0/go.mod h1:X0eyB0Gy93v0DZtSYbEM7RnMChm9Uv3j7yRXjO77xSI=
@@ -279,13 +287,16 @@ github.com/libp2p/go-libp2p-core v0.8.1 h1:+hvGysqSZ1AAWFHU8vNXX05vMSwI/6BSukuyn
 github.com/libp2p/go-libp2p-core v0.8.1/go.mod h1:FfewUH/YpvWbEB+ZY9AQRQ4TAD8sJBt/G1rVvhz5XT8=
 github.com/libp2p/go-libp2p-core v0.8.2 h1:/eaSZACWftJZYm07S0nRxdI84v1hSmgnCXrGOvJdpNQ=
 github.com/libp2p/go-libp2p-core v0.8.2/go.mod h1:FfewUH/YpvWbEB+ZY9AQRQ4TAD8sJBt/G1rVvhz5XT8=
+github.com/libp2p/go-libp2p-core v0.8.4 h1:BL0noEpCJm0FIexkHlGI3nYEW3mGpc7zy7dxRmvXpwg=
+github.com/libp2p/go-libp2p-core v0.8.4/go.mod h1:FfewUH/YpvWbEB+ZY9AQRQ4TAD8sJBt/G1rVvhz5XT8=
 github.com/libp2p/go-libp2p-crypto v0.1.0/go.mod h1:sPUokVISZiy+nNuTTH/TY+leRSxnFj/2GLjtOTW90hI=
 github.com/libp2p/go-libp2p-discovery v0.2.0/go.mod h1:s4VGaxYMbw4+4+tsoQTqh7wfxg97AEdo4GYBt6BadWg=
 github.com/libp2p/go-libp2p-discovery v0.3.0/go.mod h1:o03drFnz9BVAZdzC/QUQ+NeQOu38Fu7LJGEOK2gQltw=
 github.com/libp2p/go-libp2p-discovery v0.5.0 h1:Qfl+e5+lfDgwdrXdu4YNCWyEo3fWuP+WgN9mN0iWviQ=
 github.com/libp2p/go-libp2p-discovery v0.5.0/go.mod h1:+srtPIU9gDaBNu//UHvcdliKBIcr4SfDcm0/PfPJLug=
 github.com/libp2p/go-libp2p-loggables v0.1.0 h1:h3w8QFfCt2UJl/0/NW4K829HX/0S4KD31PQ7m8UXXO8=
 github.com/libp2p/go-libp2p-loggables v0.1.0/go.mod h1:EyumB2Y6PrYjr55Q3/tiJ/o3xoDasoRYM7nOzEpoa90=
+github.com/libp2p/go-libp2p-metrics v0.1.0/go.mod h1:rpoJmXWFxnj7qs5sJ02sxSzrhaZvpqBn8GCG6Sx6E1k=
 github.com/libp2p/go-libp2p-mplex v0.2.0/go.mod h1:Ejl9IyjvXJ0T9iqUTE1jpYATQ9NM3g+OtR+EMMODbKo=
 github.com/libp2p/go-libp2p-mplex v0.2.1/go.mod h1:SC99Rxs8Vuzrf/6WhmH41kNn13TiYdAWNYHrwImKLnE=
 github.com/libp2p/go-libp2p-mplex v0.2.2/go.mod h1:74S9eum0tVQdAfFiKxAyKzNdSuLqw5oadDq7+L/FELo=
@@ -659,6 +670,7 @@ golang.org/x/crypto v0.0.0-20181030102418-4d3f4d9ffa16/go.mod h1:6SG95UA2DQfeDnf
 golang.org/x/crypto v0.0.0-20181203042331-505ab145d0a9/go.mod h1:6SG95UA2DQfeDnfUPMdvaQW0Q7yPrPDi9nlGo2tz2b4=
 golang.org/x/crypto v0.0.0-20190211182817-74369b46fc67/go.mod h1:6SG95UA2DQfeDnfUPMdvaQW0Q7yPrPDi9nlGo2tz2b4=
 golang.org/x/crypto v0.0.0-20190225124518-7f87c0fbb88b/go.mod h1:6SG95UA2DQfeDnfUPMdvaQW0Q7yPrPDi9nlGo2tz2b4=
+golang.org/x/crypto v0.0.0-20190228161510-8dd112bcdc25/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20190313024323-a1f597ede03a/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20190426145343-a29dc8fdc734/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=

options.go

@@ -9,7 +9,6 @@ import (
 	"net"
 	"time"
 
-	circuit "github.com/libp2p/go-libp2p-circuit"
 	"github.com/libp2p/go-libp2p-core/connmgr"
 	"github.com/libp2p/go-libp2p-core/crypto"
 	"github.com/libp2p/go-libp2p-core/metrics"
@@ -206,22 +205,19 @@ func AddrsFactory(factory config.AddrsFactory) Option {
 	}
 }
 
-// EnableRelay configures libp2p to enable the relay transport with
-// configuration options. By default, this option only configures libp2p to
-// accept inbound connections from relays and make outbound connections
-// _through_ relays when requested by the remote peer. (default: enabled)
-//
-// To _act_ as a relay, pass the circuit.OptHop option.
-func EnableRelay(options ...circuit.RelayOpt) Option {
+// EnableRelay configures libp2p to enable the v2 Relay Transport.
+// It enables libp2p to accept inbound connections from v1 & v2 Relays and make outbound connections
+// _through_ v1 & v2 Relays when requested by the remote peer. (default: enabled)
+// Please see the docs in `go-libp2p-circuit/v2/` for more details.
+func EnableRelay() Option {
 	return func(cfg *Config) error {
 		cfg.RelayCustom = true
 		cfg.Relay = true
-		cfg.RelayOpts = options
 		return nil
 	}
 }
 
-// DisableRelay configures libp2p to disable the relay transport.
+// DisableRelay configures libp2p to disable the v2 Relay transport.
 func DisableRelay() Option {
 	return func(cfg *Config) error {
 		cfg.RelayCustom = true
@@ -230,38 +226,31 @@ func DisableRelay() Option {
 	}
 }
 
-// EnableAutoRelay configures libp2p to enable the AutoRelay subsystem.
+// EnableAutoRelay configures libp2p to enable the AutoRelay subsystem using statically configured v2 Relays.
 //
 // Dependencies:
 //  * Relay (enabled by default)
-//  * Routing (to find relays), or StaticRelays/DefaultStaticRelays.
-//
-// This subsystem performs two functions:
+//  * StaticV2Relays/DefaultStaticV2Relays.
 //
-// 1. When this libp2p node is configured to act as a relay "hop"
-//    (circuit.OptHop is passed to EnableRelay), this node will advertise itself
-//    as a public relay using the provided routing system.
-// 2. When this libp2p node is _not_ configured as a relay "hop", it will
-//    automatically detect if it is unreachable (e.g., behind a NAT). If so, it will
-//    find, configure, and announce a set of public relays.
+// This subsystem will enable the libp2p node to automatically detect if it is unreachable (e.g., behind a NAT). If so, it will
+// reserve slots on the configured Limited Relays and announce a set of public relay addresses.
 func EnableAutoRelay() Option {
 	return func(cfg *Config) error {
 		cfg.EnableAutoRelay = true
 		return nil
 	}
 }
 
-// StaticRelays configures known relays for autorelay; when this option is enabled
-// then the system will use the configured relays instead of querying the DHT to
-// discover relays.
+// StaticRelays configures known v2 Relays for autorelay;
+// V2 Relays are Limited Relays as opposed to V1 Relays which are unlimited Relays.
 func StaticRelays(relays []peer.AddrInfo) Option {
 	return func(cfg *Config) error {
 		cfg.StaticRelays = append(cfg.StaticRelays, relays...)
 		return nil
 	}
 }
 
-// DefaultStaticRelays configures the static relays to use the known PL-operated relays.
+// DefaultStaticRelays configures the static relays to use the known PL-operated V2 relays.
 func DefaultStaticRelays() Option {
 	return func(cfg *Config) error {
 		for _, addr := range autorelay.DefaultRelays {
@@ -462,3 +451,41 @@ func UserAgent(userAgent string) Option {
 		return nil
 	}
 }
+
+// Experimental
+// EnableHolePunching enables NAT traversal by enabling NATT'd peers to both initiate and respond to hole punching attempts
+// to create direct/NAT-traversed connections with other peers. (default: disabled)
+//
+// Dependencies:
+//  * Relay (enabled by default)
+//
+// This subsystem performs two functions:
+//
+// 1. On receiving an inbound Relay connection, it attempts to create a direct connection with the remote peer
+//    by initiating and co-ordinating a hole punch over the Relayed connection.
+// 2. If a peer sees a request to co-ordinate a hole punch on an outbound Relay connection,
+//    it will participate in the hole-punch to create a direct connection with the remote peer.
+//
+// If the hole punch is successful, all new streams will thereafter be created on the hole-punched connection.
+// The Relayed connection will eventually be closed after a grace period.
+//
+// All existing indefinite long-lived streams on the Relayed connection will have to re-opened on the hole-punched connection by the user.
+// Users can make use of the `Connected`/`Disconnected` notifications emitted by the Network for this purpose.
+//
+// It is not mandatory but nice to also enable the `AutoRelay` option (See `EnableAutoRelay`)
+// so the peer can discover and connect to Relay servers  if it discovers that it is NATT'd and has private reachability via AutoNAT.
+// This will then enable it to advertise Relay addresses which can be used to accept inbound Relay connections to then co-ordinate
+// a hole punch.
+//
+// If `EnableAutoRelay` is configured and the user is confident that the peer has private reachability/is NATT'd,
+// the `ForceReachabilityPrivate` option can be configured to short-circuit reachability discovery via AutoNAT
+// so the peer can immediately start connecting to Relay servers.
+//
+// If `EnableAutoRelay` is configured, the `StaticRelays` option can be used to configure a static set of Relay servers
+// for `AutoRelay` to connect to so that it does not need to discover Relay servers via Routing.
+func EnableHolePunching() Option {
+	return func(cfg *Config) error {
+		cfg.EnableHolePunching = true
+		return nil
+	}
+}