修复域名检查时递归查询的问题

internal/utils/lookup.go

@@ -0,0 +1,28 @@
+package utils
+
+import (
+	"github.com/miekg/dns"
+)
+
+// 获取CNAME
+func LookupCNAME(host string) (string, error) {
+	config, err := dns.ClientConfigFromFile("/etc/resolv.conf")
+	if err != nil {
+		return "", err
+	}
+
+	c := new(dns.Client)
+	m := new(dns.Msg)
+
+	m.SetQuestion(host+".", dns.TypeCNAME)
+	m.RecursionDesired = true
+	r, _, err := c.Exchange(m, config.Servers[0]+":"+config.Port)
+	if err != nil {
+		return "", err
+	}
+	if len(r.Answer) == 0 {
+		return "", nil
+	}
+
+	return r.Answer[0].(*dns.CNAME).Target, nil
+}