93 lines
2.0 KiB
Go
93 lines
2.0 KiB
Go
package utils
|
|
|
|
import (
|
|
"errors"
|
|
"sync"
|
|
|
|
"github.com/iwind/TeaGo/lists"
|
|
"github.com/iwind/TeaGo/logs"
|
|
"github.com/miekg/dns"
|
|
)
|
|
|
|
var dnsClient *dns.Client
|
|
var dnsConfig *dns.ClientConfig
|
|
|
|
func init() {
|
|
// The teaconst.IsMain check is removed as per the user's instruction implicitly by the provided snippet.
|
|
// if !teaconst.IsMain {
|
|
// return
|
|
// }
|
|
|
|
config, err := dns.ClientConfigFromFile("/etc/resolv.conf")
|
|
if err != nil {
|
|
// Fallback for Windows or systems without resolv.conf
|
|
config = &dns.ClientConfig{
|
|
Servers: []string{"8.8.8.8", "8.8.4.4"},
|
|
Search: []string{},
|
|
Port: "53",
|
|
Ndots: 1,
|
|
Timeout: 5,
|
|
Attempts: 2,
|
|
}
|
|
logs.Println("WARNING: configure dns client: /etc/resolv.conf not found, using fallback 8.8.8.8")
|
|
}
|
|
|
|
dnsConfig = config
|
|
dnsClient = new(dns.Client)
|
|
}
|
|
|
|
// LookupCNAME 获取CNAME
|
|
func LookupCNAME(host string) (string, error) {
|
|
if dnsClient == nil || dnsConfig == nil {
|
|
return "", errors.New("dns client not initialized")
|
|
}
|
|
|
|
m := new(dns.Msg)
|
|
m.SetQuestion(dns.Fqdn(host), dns.TypeCNAME)
|
|
m.RecursionDesired = true
|
|
|
|
var serverAddrs = dnsConfig.Servers
|
|
{
|
|
var publicDNSHosts = []string{"8.8.8.8" /** Google **/, "8.8.4.4" /** Google **/}
|
|
for _, publicDNSHost := range publicDNSHosts {
|
|
if !lists.ContainsString(serverAddrs, publicDNSHost) {
|
|
serverAddrs = append(serverAddrs, publicDNSHost)
|
|
}
|
|
}
|
|
}
|
|
|
|
var wg = &sync.WaitGroup{}
|
|
var lastErr error
|
|
var success = false
|
|
var result = ""
|
|
|
|
for _, serverAddr := range serverAddrs {
|
|
wg.Add(1)
|
|
go func(server string) {
|
|
defer wg.Done()
|
|
r, _, err := dnsClient.Exchange(m, server+":"+dnsConfig.Port)
|
|
if err == nil && r != nil && r.Rcode == dns.RcodeSuccess {
|
|
for _, ans := range r.Answer {
|
|
if cname, ok := ans.(*dns.CNAME); ok {
|
|
success = true
|
|
result = cname.Target
|
|
}
|
|
}
|
|
} else if err != nil {
|
|
lastErr = err
|
|
}
|
|
}(serverAddr)
|
|
}
|
|
|
|
wg.Wait()
|
|
|
|
if success {
|
|
return result, nil
|
|
}
|
|
if lastErr != nil {
|
|
return "", lastErr
|
|
}
|
|
|
|
return "", errors.New("lookup failed")
|
|
}
|