From eb3be068596717565df06fe557589ba6ac93dd5d Mon Sep 17 00:00:00 2001
From: gVisor bot <gvisor-bot@google.com>
Date: Fri, 13 Mar 2020 00:11:54 +0800
Subject: [PATCH] Fix: dns fallback logic

---
 dns/filters.go  | 2 +-
 dns/resolver.go | 5 ++---
 2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/dns/filters.go b/dns/filters.go
index 456280fa..03089d4c 100644
--- a/dns/filters.go
+++ b/dns/filters.go
@@ -14,7 +14,7 @@ type geoipFilter struct{}
 
 func (gf *geoipFilter) Match(ip net.IP) bool {
 	record, _ := mmdb.Instance().Country(ip)
-	return record.Country.IsoCode == "CN" || record.Country.IsoCode == ""
+	return record.Country.IsoCode != "CN" && record.Country.IsoCode != ""
 }
 
 type ipnetFilter struct {
diff --git a/dns/resolver.go b/dns/resolver.go
index 986aec79..dc526a7b 100644
--- a/dns/resolver.go
+++ b/dns/resolver.go
@@ -197,8 +197,7 @@ func (r *Resolver) fallbackExchange(m *D.Msg) (msg *D.Msg, err error) {
 	res := <-msgCh
 	if res.Error == nil {
 		if ips := r.msgToIP(res.Msg); len(ips) != 0 {
-			if r.shouldFallback(ips[0]) {
-				go func() { <-fallbackMsg }()
+			if !r.shouldFallback(ips[0]) {
 				msg = res.Msg
 				err = res.Error
 				return msg, err
@@ -258,7 +257,7 @@ func (r *Resolver) msgToIP(msg *D.Msg) []net.IP {
 }
 
 func (r *Resolver) asyncExchange(client []dnsClient, msg *D.Msg) <-chan *result {
-	ch := make(chan *result)
+	ch := make(chan *result, 1)
 	go func() {
 		res, err := r.batchExchange(client, msg)
 		ch <- &result{Msg: res, Error: err}