feat: support TLS by default

But don't make it the default per https://github.com/libp2p/go-libp2p/pull/710#pullrequestreview-382182995.

defaults.go

@@ -9,6 +9,7 @@ import (
 	mplex "github.com/libp2p/go-libp2p-mplex"
 	pstoremem "github.com/libp2p/go-libp2p-peerstore/pstoremem"
 	secio "github.com/libp2p/go-libp2p-secio"
+	tls "github.com/libp2p/go-libp2p-tls"
 	yamux "github.com/libp2p/go-libp2p-yamux"
 	tcp "github.com/libp2p/go-tcp-transport"
 	ws "github.com/libp2p/go-ws-transport"
@@ -19,7 +20,10 @@ import (
 //
 // Useful when you want to extend, but not replace, the supported transport
 // security protocols.
-var DefaultSecurity = Security(secio.ID, secio.New)
+var DefaultSecurity = ChainOptions(
+	Security(secio.ID, secio.New),
+	Security(tls.ID, tls.New),
+)
 
 // DefaultMuxers configures libp2p to use the stream connection multiplexers.
 //

go.mod

@@ -23,6 +23,7 @@ require (
 	github.com/libp2p/go-libp2p-secio v0.2.2
 	github.com/libp2p/go-libp2p-swarm v0.2.3
 	github.com/libp2p/go-libp2p-testing v0.1.1
+	github.com/libp2p/go-libp2p-tls v0.1.3
 	github.com/libp2p/go-libp2p-transport-upgrader v0.2.0
 	github.com/libp2p/go-libp2p-yamux v0.2.7
 	github.com/libp2p/go-maddr-filter v0.0.5

go.sum

@@ -227,6 +227,8 @@ github.com/libp2p/go-libp2p-testing v0.0.4/go.mod h1:gvchhf3FQOtBdr+eFUABet5a4MB
 github.com/libp2p/go-libp2p-testing v0.1.0/go.mod h1:xaZWMJrPUM5GlDBxCeGUi7kI4eqnjVyavGroI2nxEM0=
 github.com/libp2p/go-libp2p-testing v0.1.1 h1:U03z3HnGI7Ni8Xx6ONVZvUFOAzWYmolWf5W5jAOPNmU=
 github.com/libp2p/go-libp2p-testing v0.1.1/go.mod h1:xaZWMJrPUM5GlDBxCeGUi7kI4eqnjVyavGroI2nxEM0=
+github.com/libp2p/go-libp2p-tls v0.1.3 h1:twKMhMu44jQO+HgQK9X8NHO5HkeJu2QbhLzLJpa8oNM=
+github.com/libp2p/go-libp2p-tls v0.1.3/go.mod h1:wZfuewxOndz5RTnCAxFliGjvYSDA40sKitV4c50uI1M=
 github.com/libp2p/go-libp2p-transport-upgrader v0.1.1/go.mod h1:IEtA6or8JUbsV07qPW4r01GnTenLW4oi3lOPbUMGJJA=
 github.com/libp2p/go-libp2p-transport-upgrader v0.2.0 h1:5EhPgQhXZNyfL22ERZTUoVp9UVVbNowWNVtELQaKCHk=
 github.com/libp2p/go-libp2p-transport-upgrader v0.2.0/go.mod h1:mQcrHj4asu6ArfSoMuyojOdjx73Q47cYD7s5+gZOlns=
@@ -468,6 +470,7 @@ golang.org/x/sys v0.0.0-20190228124157-a34e9553db1e/go.mod h1:STP8DvDyc/dI5b8T5h
 golang.org/x/sys v0.0.0-20190405154228-4b34438f7a67/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20190502145724-3ef323f4f1fd/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20190526052359-791d8a0f4d09/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20190626221950-04f50cda93cb/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20190924154521-2837fb4f24fe/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20191120155948-bd437916bb0e/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=