Add a gRPC router wrapper, useful for the upcoming grpc controller example

Former-commit-id: ae4c29597ce1336a74278b86b59d08b6c91eab0a

_examples/websocket/socketio/main.go

@@ -52,3 +52,8 @@ func main() {
 		iris.WithoutServerError(iris.ErrServerClosed),
 	)
 }
+
+/*
+If you want to enable CORS in your websocket handler,
+please follow this post: https://github.com/googollee/go-socket.io/issues/242
+*/

middleware/grpc/grpc.go

@@ -0,0 +1,30 @@
+package grpc
+
+import (
+	"net/http"
+	"strings"
+
+	"github.com/kataras/iris/v12/core/router"
+)
+
+// New returns a new gRPC Iris router wrapper for a gRPC server.
+// useful when you want to share one port (such as 443 for https) between gRPC and Iris.
+//
+// The Iris server SHOULD run under HTTP/2 and clients too.
+//
+// Usage:
+//  import grpcWrapper "github.com/kataras/iris/v12/middleware/grpc"
+//  [...]
+//  app := iris.New()
+//  grpcServer := grpc.NewServer()
+//  app.WrapRouter(grpcWrapper.New(grpcServer))
+func New(grpcServer http.Handler) router.WrapperFunc {
+	return func(w http.ResponseWriter, r *http.Request, mux http.HandlerFunc) {
+		if r.ProtoMajor == 2 && strings.HasPrefix(
+			r.Header.Get("Content-Type"), "application/grpc") {
+			grpcServer.ServeHTTP(w, r)
+		} else {
+			mux.ServeHTTP(w, r)
+		}
+	}
+}