style:包名小写

util/checker.go

@@ -0,0 +1,23 @@
+package util
+
+import (
+	"context"
+	"net"
+)
+
+type checker struct{}
+
+var Checker checker
+
+func (checker) NetOk() bool {
+	r := &net.Resolver{ //指定DNS，防止本地DNS缓存影响
+		PreferGo: true,
+		Dial:     NetDailEr(),
+	}
+	if ip, err := r.LookupIP(context.Background(), "ip4", "www.msftconnecttest.com"); err != nil { //通过DNS确认是否在线
+		return false
+	} else if len(ip) == 0 || ip[0].String() != "13.107.4.52" {
+		return false
+	}
+	return true
+}