Add GRPC server to SMM

grpc/api_key_interceptor.go

@@ -0,0 +1,26 @@
+package grpc
+
+import (
+	"context"
+	"errors"
+
+	"github.com/PretendoNetwork/super-mario-maker/globals"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/metadata"
+)
+
+func apiKeyInterceptor(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (interface{}, error) {
+	md, ok := metadata.FromIncomingContext(ctx)
+
+	if ok {
+		apiKeyHeader := md.Get("X-API-Key")
+
+		if len(apiKeyHeader) == 0 || apiKeyHeader[0] != globals.GRPCAPIKey {
+			return nil, errors.New("Missing or invalid API key")
+		}
+	}
+
+	h, err := handler(ctx, req)
+
+	return h, err
+}