daemon option to optionally disable secio

This commit adds an option to turn off all encryption. This is a mode
used for tests, debugging, achieving protocol implementation interop,
learning about how the protocol works (nc ftw), and worst case
networks which _demand_ to be able to snoop on all the traffic.
(sadly, there are some private intranets like this...). (We should
consider at least _signing_ all this traffic.)

Because of the severity of this sort of thing, this is an
all-or-nothing deal. Either encryption is ON or OFF _fully_.
This way, partially unencrypted nodes cannot be accidentally left
running without the user's understanding. Nodes without encrypted
connections will simply not be able to speak to any of the global
bootstrap nodes, or anybody in the public network.

License: MIT
Signed-off-by: Juan Batiz-Benet <juan@benet.ai>

net/conn/dial.go

@@ -60,7 +60,7 @@ func (d *Dialer) Dial(ctx context.Context, raddr ma.Multiaddr, remote peer.ID) (
 			return
 		}
 
-		if d.PrivateKey == nil {
+		if d.PrivateKey == nil || EncryptConnections == false {
 			log.Warning("dialer %s dialing INSECURELY %s at %s!", d, remote, raddr)
 			connOut = c
 			return

net/conn/interface.go

@@ -93,3 +93,11 @@ type Listener interface {
 	// Any blocked Accept operations will be unblocked and return errors.
 	Close() error
 }
+
+// EncryptConnections is a global parameter because it should either be
+// enabled or _completely disabled_. I.e. a node should only be able to talk
+// to proper (encrypted) networks if it is encrypting all its transports.
+// Running a node with disabled transport encryption is useful to debug the
+// protocols, achieve implementation interop, or for private networks which
+// -- for whatever reason -- _must_ run unencrypted.
+var EncryptConnections = true

net/conn/listen.go

@@ -107,7 +107,7 @@ func (l *listener) Accept() (net.Conn, error) {
 			return nil, err
 		}
 
-		if l.privk == nil {
+		if l.privk == nil || EncryptConnections == false {
 			log.Warning("listener %s listening INSECURELY!", l)
 			return c, nil
 		}