Add an example for serving HTTP and HTTPS

This commit adds a simple Go doc example for serving HTTP and HTTPS on
the same port.

example_tls_test.go

@@ -0,0 +1,70 @@
+package cmux_test
+
+import (
+	"crypto/rand"
+	"crypto/tls"
+	"fmt"
+	"log"
+	"net"
+	"net/http"
+
+	"github.com/soheilhy/cmux"
+)
+
+type anotherHTTPHandler struct{}
+
+func (h *anotherHTTPHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	fmt.Fprintf(w, "example http response")
+}
+
+func serveHTTP1(l net.Listener) {
+	s := &http.Server{
+		Handler: &anotherHTTPHandler{},
+	}
+	s.Serve(l)
+}
+
+func serveHTTPS(l net.Listener) {
+	// Load certificates.
+	certificate, err := tls.LoadX509KeyPair("cert.pem", "key.pem")
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	config := &tls.Config{
+		Certificates: []tls.Certificate{certificate},
+		Rand:         rand.Reader,
+	}
+
+	// Create TLS listener.
+	tlsl := tls.NewListener(l, config)
+
+	// Serve HTTP over TLS.
+	serveHTTP1(tlsl)
+}
+
+// This is an example is serving HTTP and HTTPS on the same port.
+func Example_bothHTTPAndHTTPS() {
+	// Create the TCP listener.
+	l, err := net.Listen("tcp", "127.0.0.1:50051")
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// Create a mux.
+	m := cmux.New(l)
+
+	// We first match on HTTP 1.1 methods.
+	httpl := m.Match(cmux.HTTP1Fast())
+
+	// If not matched, we assume that its TLS.
+	//
+	// Note that you can take this listener, do TLS handshake and
+	// create another mux to multiplex the connections over TLS.
+	tlsl := m.Match(cmux.Any())
+
+	go serveHTTP1(httpl)
+	go serveHTTPS(tlsl)
+
+	m.Serve()
+}