rpcserver: GET / support (#36)

examples/rpcserver/main.go

@@ -0,0 +1,40 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+
+	"github.com/flashbots/go-utils/rpcserver"
+)
+
+var listenAddr = ":8080"
+
+func main() {
+	handler, err := rpcserver.NewJSONRPCHandler(
+		rpcserver.Methods{
+			"test_foo": HandleTestFoo,
+		},
+		rpcserver.JSONRPCHandlerOpts{
+			ServerName:         "public_server",
+			GetResponseContent: []byte("Hello world"),
+		},
+	)
+	if err != nil {
+		panic(err)
+	}
+
+	// server
+	server := &http.Server{
+		Addr:    listenAddr,
+		Handler: handler,
+	}
+	fmt.Println("Starting server.", "listenAddr:", listenAddr)
+	if err := server.ListenAndServe(); err != nil {
+		panic(err)
+	}
+}
+
+func HandleTestFoo(ctx context.Context) (string, error) {
+	return "foo", nil
+}

rpcserver/jsonrpc_server.go

@@ -92,6 +92,8 @@ type JSONRPCHandlerOpts struct {
 	// If true extract value from x-flashbots-origin header
 	// Result can be extracted from the context using GetOrigin
 	ExtractOriginFromHeader bool
+	// GET response content
+	GetResponseContent []byte
 }
 
 // NewJSONRPCHandler creates JSONRPC http.Handler from the map that maps method names to method functions
@@ -157,6 +159,19 @@ func (h *JSONRPCHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	}()
 
 	if r.Method != http.MethodPost {
+		// Respond with GET response content if it's set
+		if r.Method == http.MethodGet && len(h.GetResponseContent) > 0 {
+			w.WriteHeader(http.StatusOK)
+			_, err := w.Write(h.GetResponseContent)
+			if err != nil {
+				http.Error(w, errMarshalResponse, http.StatusInternalServerError)
+				incInternalErrors(h.ServerName)
+				return
+			}
+			return
+		}
+
+		// Responsd with "only POST method is allowed"
 		http.Error(w, errMethodNotAllowed, http.StatusMethodNotAllowed)
 		incIncorrectRequest(h.ServerName)
 		return