From c42303e93ed101786db7182ad9385185eaeed8e2 Mon Sep 17 00:00:00 2001
From: Star Brilliant <coder@poorlab.com>
Date: Thu, 30 Nov 2017 17:09:55 +0800
Subject: [PATCH] Improve DNS error handling

---
 doh-client/client.go  | 9 ++++++++-
 json-dns/unmarshal.go | 1 -
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/doh-client/client.go b/doh-client/client.go
index 20e6bfe..3ee543a 100644
--- a/doh-client/client.go
+++ b/doh-client/client.go
@@ -198,7 +198,10 @@ func (c *Client) handlerFunc(w dns.ResponseWriter, r *dns.Msg, isTCP bool) {
 		log.Printf("HTTP error: %s\n", resp.Status)
 		reply.Rcode = dns.RcodeServerFailure
 		w.WriteMsg(reply)
-		return
+		contentType := resp.Header.Get("Content-Type")
+		if contentType != "application/json" && !strings.HasPrefix(contentType, "application/json;") {
+			return
+		}
 	}
 
 	body, err := ioutil.ReadAll(resp.Body)
@@ -218,6 +221,10 @@ func (c *Client) handlerFunc(w dns.ResponseWriter, r *dns.Msg, isTCP bool) {
 		return
 	}
 
+	if respJson.Status != dns.RcodeSuccess && respJson.Comment != "" {
+		log.Printf("DNS error: %s\n", respJson.Comment)
+	}
+
 	fullReply := jsonDNS.Unmarshal(reply, &respJson, udpSize, ednsClientNetmask)
 	buf, err := fullReply.Pack()
 	if err != nil {
diff --git a/json-dns/unmarshal.go b/json-dns/unmarshal.go
index e26b3c5..c97fc69 100644
--- a/json-dns/unmarshal.go
+++ b/json-dns/unmarshal.go
@@ -52,7 +52,6 @@ func Unmarshal(msg *dns.Msg, resp *Response, udpSize uint16, ednsClientNetmask u
 
 	reply := msg.Copy()
 	reply.Truncated = resp.TC
-	reply.RecursionDesired = resp.RD
 	reply.RecursionAvailable = resp.RA
 	reply.AuthenticatedData = resp.AD
 	reply.CheckingDisabled = resp.CD