obfsvpn: allow wrapping existing connections

This can be used to add support for additional networks that we don't
necessarily want to depend on in the library.

Signed-off-by: Sam Whited <sam@samwhited.com>

1 files changed, 15 insertions, 3 deletions

diff --git a/dialer.go b/dialer.go
index 444e0c2..5043aeb 100644
--- a/dialer.go
+++ b/dialer.go
@@ -120,8 +120,22 @@ func NewDialerArgs(args pt.Args) (*Dialer, error) {
 	}, nil
 }
 
+// Wrap performs the ntor handshake over an existing conection.
+// Wrap ignores the underlying Dialer config.
+func (d *Dialer) Wrap(ctx context.Context, conn net.Conn) (net.Conn, error) {
+	return d.dial(ctx, "", "", func(network, address string) (net.Conn, error) {
+		return conn, nil
+	})
+}
+
 // Dial creates an outbound net.Conn and performs the ntor handshake.
 func (d *Dialer) Dial(ctx context.Context, network, address string) (net.Conn, error) {
+	return d.dial(ctx, network, address, func(network, address string) (net.Conn, error) {
+		return d.Dialer.DialContext(ctx, network, address)
+	})
+}
+
+func (d *Dialer) dial(ctx context.Context, network, address string, f func(network, address string) (net.Conn, error)) (net.Conn, error) {
 	if d.cf == nil {
 		cf, err := (&obfs4.Transport{}).ClientFactory("")
 		if err != nil {
@@ -134,9 +148,7 @@ func (d *Dialer) Dial(ctx context.Context, network, address string) (net.Conn, e
 	if err != nil {
 		return nil, err
 	}
-	return d.cf.Dial(network, address, func(network, address string) (net.Conn, error) {
-		return d.Dialer.DialContext(ctx, network, address)
-	}, args)
+	return d.cf.Dial(network, address, f, args)
 }
 
 // Args returns the dialers options as pluggable transport arguments.