From 5fb9dfcfeeb8294d4d2e8a7b3e496eed5c3f2a9d Mon Sep 17 00:00:00 2001
From: wweir <wweir@foxmail.com>
Date: Sat, 25 Apr 2026 03:06:25 +0800
Subject: [PATCH] fix(router): skip empty country mmdb

---
 router/router.go      | 12 ++++++++----
 router/router_test.go | 22 ++++++++++++++++++++++
 2 files changed, 30 insertions(+), 4 deletions(-)

diff --git a/router/router.go b/router/router.go
index b848dd5..8d5fb66 100644
--- a/router/router.go
+++ b/router/router.go
@@ -6,6 +6,7 @@ import (
 	"log/slog"
 	"net"
 	"strconv"
+	"strings"
 	"sync"
 	"time"
 
@@ -63,10 +64,13 @@ func NewRouter(serveIPs []string, upstreamDNS, fallbackDNS, mmdbFile string, pro
 		}
 	}
 
-	var err error
-	r.country.Reader, err = geoip2.Open(mmdbFile)
-	if err != nil {
-		slog.Warn("open geoip2 db", "error", err, "file", mmdbFile)
+	mmdbFile = strings.TrimSpace(mmdbFile)
+	if mmdbFile != "" {
+		var err error
+		r.country.Reader, err = geoip2.Open(mmdbFile)
+		if err != nil {
+			slog.Warn("open geoip2 db", "error", err, "file", mmdbFile)
+		}
 	}
 
 	return &r
diff --git a/router/router_test.go b/router/router_test.go
index c2c9a56..3bd3040 100644
--- a/router/router_test.go
+++ b/router/router_test.go
@@ -1,8 +1,10 @@
 package router
 
 import (
+	"bytes"
 	"errors"
 	"io"
+	"log/slog"
 	"net"
 	"net/http"
 	"strings"
@@ -142,6 +144,26 @@ func TestAddCountryCIDRsSkipsInvalidEntries(t *testing.T) {
 	}
 }
 
+func TestNewRouterSkipsEmptyCountryMMDB(t *testing.T) {
+	var logs bytes.Buffer
+	previous := slog.Default()
+	slog.SetDefault(slog.New(slog.NewTextHandler(&logs, nil)))
+	t.Cleanup(func() {
+		slog.SetDefault(previous)
+	})
+
+	for _, mmdbFile := range []string{"", "   "} {
+		r := NewRouter(nil, "", "223.5.5.5", mmdbFile, nil)
+		if r.country.Reader != nil {
+			t.Fatalf("expected empty MMDB %q to disable GeoIP lookup", mmdbFile)
+		}
+	}
+
+	if strings.Contains(logs.String(), "open geoip2 db") {
+		t.Fatalf("empty MMDB should not emit open warning, logs: %s", logs.String())
+	}
+}
+
 func TestIsAccessChecksRequestedPortOnly(t *testing.T) {
 	t.Parallel()