From abdd033310dcf687eb1c7a824182a99aba7c9d0e Mon Sep 17 00:00:00 2001
From: Star Brilliant <coder@poorlab.com>
Date: Tue, 12 Jun 2018 11:12:13 +0800
Subject: [PATCH] Print upstream information if error happens

---
 doh-client/client.go  |  1 +
 doh-client/google.go  |  3 ++-
 doh-client/ietf.go    |  3 ++-
 doh-client/version.go |  2 +-
 doh-server/server.go  | 29 +++++++++++++++--------------
 doh-server/version.go |  2 +-
 6 files changed, 22 insertions(+), 18 deletions(-)

diff --git a/doh-client/client.go b/doh-client/client.go
index 5de26e2..b4d31f2 100644
--- a/doh-client/client.go
+++ b/doh-client/client.go
@@ -58,6 +58,7 @@ type DNSRequest struct {
 	udpSize           uint16
 	ednsClientAddress net.IP
 	ednsClientNetmask uint8
+	currentUpstream   string
 	err               error
 }
 
diff --git a/doh-client/google.go b/doh-client/google.go
index adeaeb2..a6cb5c5 100644
--- a/doh-client/google.go
+++ b/doh-client/google.go
@@ -115,12 +115,13 @@ func (c *Client) generateRequestGoogle(w dns.ResponseWriter, r *dns.Msg, isTCP b
 		udpSize:           udpSize,
 		ednsClientAddress: ednsClientAddress,
 		ednsClientNetmask: ednsClientNetmask,
+		currentUpstream:   upstream,
 	}
 }
 
 func (c *Client) parseResponseGoogle(w dns.ResponseWriter, r *dns.Msg, isTCP bool, req *DNSRequest) {
 	if req.response.StatusCode != 200 {
-		log.Printf("HTTP error: %s\n", req.response.Status)
+		log.Printf("HTTP error from upstream %s: %s\n", req.currentUpstream, req.response.Status)
 		req.reply.Rcode = dns.RcodeServerFailure
 		contentType := req.response.Header.Get("Content-Type")
 		if contentType != "application/json" && !strings.HasPrefix(contentType, "application/json;") {
diff --git a/doh-client/ietf.go b/doh-client/ietf.go
index 5615737..6aae281 100644
--- a/doh-client/ietf.go
+++ b/doh-client/ietf.go
@@ -175,12 +175,13 @@ func (c *Client) generateRequestIETF(w dns.ResponseWriter, r *dns.Msg, isTCP boo
 		udpSize:           udpSize,
 		ednsClientAddress: ednsClientAddress,
 		ednsClientNetmask: ednsClientNetmask,
+		currentUpstream:   upstream,
 	}
 }
 
 func (c *Client) parseResponseIETF(w dns.ResponseWriter, r *dns.Msg, isTCP bool, req *DNSRequest) {
 	if req.response.StatusCode != 200 {
-		log.Printf("HTTP error: %s\n", req.response.Status)
+		log.Printf("HTTP error from upstream %s: %s\n", req.currentUpstream, req.response.Status)
 		req.reply.Rcode = dns.RcodeServerFailure
 		contentType := req.response.Header.Get("Content-Type")
 		if contentType != "application/dns-message" && !strings.HasPrefix(contentType, "application/dns-message;") {
diff --git a/doh-client/version.go b/doh-client/version.go
index ac25430..4e89ef5 100644
--- a/doh-client/version.go
+++ b/doh-client/version.go
@@ -24,6 +24,6 @@
 package main
 
 const (
-	VERSION    = "1.3.6"
+	VERSION    = "1.3.7"
 	USER_AGENT = "DNS-over-HTTPS/" + VERSION + " (+https://github.com/m13253/dns-over-https)"
 )
diff --git a/doh-server/server.go b/doh-server/server.go
index 6197352..557e75b 100644
--- a/doh-server/server.go
+++ b/doh-server/server.go
@@ -46,11 +46,12 @@ type Server struct {
 }
 
 type DNSRequest struct {
-	request    *dns.Msg
-	response   *dns.Msg
-	isTailored bool
-	errcode    int
-	errtext    string
+	request         *dns.Msg
+	response        *dns.Msg
+	currentUpstream string
+	isTailored      bool
+	errcode         int
+	errtext         string
 }
 
 func NewServer(conf *config) (s *Server) {
@@ -164,7 +165,7 @@ func (s *Server) handlerFunc(w http.ResponseWriter, r *http.Request) {
 	}
 
 	var err error
-	req.response, err = s.doDNSQuery(req.request)
+	req, err = s.doDNSQuery(req)
 	if err != nil {
 		jsonDNS.FormatError(w, fmt.Sprintf("DNS query failure (%s)", err.Error()), 503)
 		return
@@ -208,23 +209,23 @@ func (s *Server) findClientIP(r *http.Request) net.IP {
 	return nil
 }
 
-func (s *Server) doDNSQuery(msg *dns.Msg) (resp *dns.Msg, err error) {
+func (s *Server) doDNSQuery(req *DNSRequest) (resp *DNSRequest, err error) {
 	numServers := len(s.conf.Upstream)
 	for i := uint(0); i < s.conf.Tries; i++ {
-		server := s.conf.Upstream[rand.Intn(numServers)]
+		req.currentUpstream = s.conf.Upstream[rand.Intn(numServers)]
 		if !s.conf.TCPOnly {
-			resp, _, err = s.udpClient.Exchange(msg, server)
+			req.response, _, err = s.udpClient.Exchange(req.request, req.currentUpstream)
 			if err == dns.ErrTruncated {
 				log.Println(err)
-				resp, _, err = s.tcpClient.Exchange(msg, server)
+				req.response, _, err = s.tcpClient.Exchange(req.request, req.currentUpstream)
 			}
 		} else {
-			resp, _, err = s.tcpClient.Exchange(msg, server)
+			req.response, _, err = s.tcpClient.Exchange(req.request, req.currentUpstream)
 		}
 		if err == nil {
-			return
+			return req, nil
 		}
-		log.Println(err)
+		log.Printf("DNS error from upstream %s: %s\n", req.currentUpstream, err.Error())
 	}
-	return
+	return req, err
 }
diff --git a/doh-server/version.go b/doh-server/version.go
index ac25430..4e89ef5 100644
--- a/doh-server/version.go
+++ b/doh-server/version.go
@@ -24,6 +24,6 @@
 package main
 
 const (
-	VERSION    = "1.3.6"
+	VERSION    = "1.3.7"
 	USER_AGENT = "DNS-over-HTTPS/" + VERSION + " (+https://github.com/m13253/dns-over-https)"
 )