From 4ac06a342b48e25cf79773a7d9d1cf57f0f6c564 Mon Sep 17 00:00:00 2001
From: dilyevsky <ilyevsky@gmail.com>
Date: Mon, 17 Sep 2018 10:21:12 -0700
Subject: [PATCH] [plugin/proxy]: Return on WriteMsg err. (#2096)

* [plugin/proxy]: Return on WriteMsg err.

Followup PR on the heels of #2050. Short-circut and log on error from
`WriteMsg`. This will prevent code getting stuck on `ReadMsg` and allow
for easier debugging.

Also simply the `ReadMsg` calling code a little - remove double `Close` (already called above).
---
 plugin/proxy/dns.go | 13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/plugin/proxy/dns.go b/plugin/proxy/dns.go
index c1aa7f190..a96762c1d 100644
--- a/plugin/proxy/dns.go
+++ b/plugin/proxy/dns.go
@@ -89,15 +89,12 @@ func exchange(m *dns.Msg, co net.Conn) (*dns.Msg, error) {
 
 	writeDeadline := time.Now().Add(defaultTimeout)
 	dnsco.SetWriteDeadline(writeDeadline)
-	dnsco.WriteMsg(m)
+	if err := dnsco.WriteMsg(m); err != nil {
+		log.Debugf("Failed to send message: %v", err)
+		return nil, err
+	}
 
 	readDeadline := time.Now().Add(defaultTimeout)
 	co.SetReadDeadline(readDeadline)
-	r, err := dnsco.ReadMsg()
-
-	dnsco.Close()
-	if r == nil {
-		return nil, err
-	}
-	return r, err
+	return dnsco.ReadMsg()
 }