cache dns maybe

main.go

@@ -1,13 +1,18 @@
 package main
 
 import (
+	"context"
 	"crypto/tls"
 	"fmt"
 	"log"
+	"net"
 	"net/http"
 	"net/http/httputil"
 	"net/url"
 	"strings"
+	"time"
+
+	"github.com/viki-org/dnscache"
 )
 
 func main() {
@@ -32,6 +37,8 @@ func main() {
 	}
 }
 
+var resolver = dnscache.New(time.Minute * 500)
+
 func (c Config) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	endpoint := c.endpoint(r)
 	if endpoint.To == "" {
@@ -71,8 +78,18 @@ func (c Config) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	if err != nil {
 		log.Printf("[%s] %v", c.key(r), err)
 	}
+
 	var transport http.Transport
 	transport.TLSClientConfig = &tls.Config{InsecureSkipVerify: true}
+	if ip, _ := resolver.FetchOneString(strings.Split(u.Host, ":")[0]); ip != "" {
+		transport.DialContext = func(ctx context.Context, network string, address string) (net.Conn, error) {
+			if idx := strings.LastIndex(u.Host, ":"); idx > 0 {
+				ip = ip + u.Host[idx:]
+			}
+			return (&net.Dialer{}).DialContext(ctx, network, ip)
+		}
+	}
+
 	proxy := httputil.NewSingleHostReverseProxy(u)
 	proxy.Transport = redirPurge{
 		proxyHost:     r.Host,