add resolver

pkg/handler/dns/metadata.go

@@ -1,6 +1,8 @@
 package dns
 
 import (
+	"net"
+	"strings"
 	"time"
 
 	mdata "github.com/go-gost/gost/pkg/metadata"
@@ -11,10 +13,10 @@ type metadata struct {
 	retryCount  int
 	ttl         time.Duration
 	timeout     time.Duration
-	prefer      string
-	clientIP    string
+	clientIP    net.IP
 	// nameservers
 	servers []string
+	dns     []string // compatible with v2
 }
 
 func (h *dnsHandler) parseMetadata(md mdata.Metadata) (err error) {
@@ -23,9 +25,9 @@ func (h *dnsHandler) parseMetadata(md mdata.Metadata) (err error) {
 		retryCount  = "retry"
 		ttl         = "ttl"
 		timeout     = "timeout"
-		prefer      = "prefer"
 		clientIP    = "clientIP"
 		servers     = "servers"
+		dns         = "dns"
 	)
 
 	h.md.readTimeout = mdata.GetDuration(md, readTimeout)
@@ -35,9 +37,15 @@ func (h *dnsHandler) parseMetadata(md mdata.Metadata) (err error) {
 	if h.md.timeout <= 0 {
 		h.md.timeout = 5 * time.Second
 	}
-	h.md.prefer = mdata.GetString(md, prefer)
-	h.md.clientIP = mdata.GetString(md, clientIP)
+	sip := mdata.GetString(md, clientIP)
+	if sip != "" {
+		h.md.clientIP = net.ParseIP(sip)
+	}
 	h.md.servers = mdata.GetStrings(md, servers)
+	h.md.dns = strings.Split(mdata.GetString(md, dns), ",")
+	if len(h.md.dns) > 0 {
+		h.md.servers = append(h.md.servers, h.md.dns...)
+	}
 
 	return
 }