From 447519948102c96313390857dc743346491ec45a Mon Sep 17 00:00:00 2001
From: Ben Schwartz <bemasc@google.com>
Date: Thu, 25 Jun 2020 20:47:55 -0400
Subject: [PATCH 1/2] Fix query construction error

Queries weren't setting the "RD" bit, so they were not actually
traversing the recursive resolver as intended.
---
 choir_test.go             |  6 ++++++
 client.go                 |  1 +
 example/example_client.go | 21 ++++++++++++++++++++-
 3 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/choir_test.go b/choir_test.go
index 1015648..c58f726 100644
--- a/choir_test.go
+++ b/choir_test.go
@@ -288,6 +288,12 @@ func TestFormat(t *testing.T) {
 	if err := msg.Unpack(query); err != nil {
 		t.Fatal(err)
 	}
+	if msg.Header.OpCode != 0 {
+		t.Error("Message is not a question")
+	}
+	if !msg.Header.RecursionDesired {
+		t.Error("Query doesn't request recursion")
+	}
 	question := msg.Questions[0]
 	expectedQuestion := dnsmessage.Question{
 		Name:  dnsmessage.MustNewName(name + "."),
diff --git a/client.go b/client.go
index f88fb92..76e0a90 100644
--- a/client.go
+++ b/client.go
@@ -153,6 +153,7 @@ func formatQuery(name string) ([]byte, error) {
 	binary.BigEndian.PutUint16(ecsPayload[2:], ecsPrefixLength)
 
 	msg := &dnsmessage.Message{
+		Header: dnsmessage.Header{RecursionDesired: true},
 		Questions: []dnsmessage.Question{{
 			Name:  n,
 			Type:  dnsmessage.TypeTXT,
diff --git a/example/example_client.go b/example/example_client.go
index 325d5ef..34197c7 100644
--- a/example/example_client.go
+++ b/example/example_client.go
@@ -85,7 +85,26 @@ func (s udpDNSReportSender) Send(r choir.Report) error {
 	if err != nil {
 		log.Fatal("Failed to reach resolver:", err)
 	}
-	c.Write(query)
+	if _, err := c.Write(query); err != nil {
+		log.Printf("Warning: Query failed: %v", err)
+	} else {
+		var buf [4096]byte
+		c.SetReadDeadline(time.Now().Add(5 * time.Second))
+		n, err := c.Read(buf[:])
+		if err != nil {
+			log.Printf("Reading response failed: %v", err)
+		} else {
+			var msg dnsmessage.Message
+			if err := msg.Unpack(buf[:n]); err != nil {
+				log.Printf("Bad response: %v", err)
+			} else if msg.Header.RCode != dnsmessage.RCodeNameError {
+				// We expect an NXDOMAIN response.  Anything else is surprising.
+				log.Printf("Unexpected response: %v", msg.Header.RCode)
+			} else {
+				log.Printf("Report complete")
+			}
+		}
+	}
 	c.Close()
 	return nil
 }

From 55db4689eb71b8b12222c66a8262f63eee179bec Mon Sep 17 00:00:00 2001
From: Ben Schwartz <bemasc@google.com>
Date: Fri, 26 Jun 2020 12:46:40 -0400
Subject: [PATCH 2/2] Reduce nesting in the client example

---
 example/example_client.go | 42 ++++++++++++++++++++-------------------
 1 file changed, 22 insertions(+), 20 deletions(-)

diff --git a/example/example_client.go b/example/example_client.go
index 34197c7..9d6fbe3 100644
--- a/example/example_client.go
+++ b/example/example_client.go
@@ -83,29 +83,31 @@ func (s udpDNSReportSender) Send(r choir.Report) error {
 	log.Printf("Querying %s via %s\n", name, s.serverAddress)
 	c, err := net.Dial("udp", s.serverAddress)
 	if err != nil {
-		log.Fatal("Failed to reach resolver:", err)
+		return fmt.Errorf("Failed to reach resolver: %w", err)
 	}
+	defer c.Close()
+
 	if _, err := c.Write(query); err != nil {
-		log.Printf("Warning: Query failed: %v", err)
-	} else {
-		var buf [4096]byte
-		c.SetReadDeadline(time.Now().Add(5 * time.Second))
-		n, err := c.Read(buf[:])
-		if err != nil {
-			log.Printf("Reading response failed: %v", err)
-		} else {
-			var msg dnsmessage.Message
-			if err := msg.Unpack(buf[:n]); err != nil {
-				log.Printf("Bad response: %v", err)
-			} else if msg.Header.RCode != dnsmessage.RCodeNameError {
-				// We expect an NXDOMAIN response.  Anything else is surprising.
-				log.Printf("Unexpected response: %v", msg.Header.RCode)
-			} else {
-				log.Printf("Report complete")
-			}
-		}
+		return fmt.Errorf("Query failed: %w", err)
 	}
-	c.Close()
+
+	var buf [4096]byte
+	c.SetReadDeadline(time.Now().Add(5 * time.Second))
+	n, err := c.Read(buf[:])
+	if err != nil {
+		return fmt.Errorf("Reading response failed: %w", err)
+	}
+
+	var response dnsmessage.Message
+	if err := response.Unpack(buf[:n]); err != nil {
+		return fmt.Errorf("Bad response: %w", err)
+	}
+	if response.Header.RCode != dnsmessage.RCodeNameError {
+		// We expect an NXDOMAIN response.  Anything else is surprising.
+		return fmt.Errorf("Unexpected response: %v", response.Header.RCode)
+	}
+
+	log.Printf("Report complete")
 	return nil
 }