支持任意域名通过CNAME访问服务（开启选项后）

internal/utils/lookup.go

@@ -0,0 +1,35 @@
+package utils
+
+import (
+	"github.com/TeaOSLab/EdgeCommon/pkg/configutils"
+	"github.com/miekg/dns"
+)
+
+// LookupCNAME 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
+
+	var lastErr error
+	for _, serverAddr := range config.Servers {
+		r, _, err := c.Exchange(m, configutils.QuoteIP(serverAddr)+":"+config.Port)
+		if err != nil {
+			lastErr = err
+			continue
+		}
+		if len(r.Answer) == 0 {
+			continue
+		}
+
+		return r.Answer[0].(*dns.CNAME).Target, nil
+	}
+	return "", lastErr
+}