github.com/TeaOSLab/EdgeNode@v1.3.8/internal/utils/lookup.go (about)

     1  package utils
     2  
     3  import (
     4  	"github.com/TeaOSLab/EdgeCommon/pkg/configutils"
     5  	"github.com/miekg/dns"
     6  )
     7  
     8  // LookupCNAME 获取CNAME
     9  func LookupCNAME(host string) (string, error) {
    10  	config, err := dns.ClientConfigFromFile("/etc/resolv.conf")
    11  	if err != nil {
    12  		return "", err
    13  	}
    14  
    15  	c := new(dns.Client)
    16  	m := new(dns.Msg)
    17  
    18  	m.SetQuestion(host+".", dns.TypeCNAME)
    19  	m.RecursionDesired = true
    20  
    21  	var lastErr error
    22  	for _, serverAddr := range config.Servers {
    23  		r, _, err := c.Exchange(m, configutils.QuoteIP(serverAddr)+":"+config.Port)
    24  		if err != nil {
    25  			lastErr = err
    26  			continue
    27  		}
    28  		if len(r.Answer) == 0 {
    29  			continue
    30  		}
    31  
    32  		return r.Answer[0].(*dns.CNAME).Target, nil
    33  	}
    34  	return "", lastErr
    35  }