Bringing back and changing some tests

conn.go

@@ -713,7 +713,7 @@ func (c *Conn) writeToSocket(
 	}
 }
 
-func (c *Conn) createAnswer(id uint16, q dnsmessage.Question, addr netip.Addr, config *Config) (dnsmessage.Message, error) {
+func createAnswer(id uint16, q dnsmessage.Question, addr netip.Addr, config *Config) (dnsmessage.Message, error) {
 	packedName, err := dnsmessage.NewName(q.Name.String())
 	if err != nil {
 		return dnsmessage.Message{}, err
@@ -767,7 +767,7 @@ func (c *Conn) createAnswer(id uint16, q dnsmessage.Question, addr netip.Addr, c
 }
 
 func (c *Conn) sendAnswer(queryID uint16, q dnsmessage.Question, ifIndex int, result netip.Addr, dst *net.UDPAddr, config *Config) {
-	answer, err := c.createAnswer(queryID, q, result, config)
+	answer, err := createAnswer(queryID, q, result, config)
 	if err != nil {
 		c.log.Warnf("[%s] failed to create mDNS answer %v", c.name, err)
 		return
@@ -1066,7 +1066,7 @@ func (c *Conn) readLoop(name string, pktConn ipPacketConn, inboundBufferSize int
 					for _, query := range queries {
 						queryCopy := query
 						if queryCopy.nameWithSuffix == a.Header.Name.String() {
-							addr, err := addrFromAnswerHeader(a)
+							addr, err := addrFromAnswer(a)
 							if err != nil {
 								c.log.Warnf("[%s] failed to parse mDNS answer %v", c.name, err)
 								return
@@ -1166,7 +1166,7 @@ func (c *Conn) start(started chan<- struct{}, inboundBufferSize int, config *Con
 	}
 }
 
-func addrFromAnswerHeader(answer dnsmessage.Resource) (*netip.Addr, error) {
+func addrFromAnswer(answer dnsmessage.Resource) (*netip.Addr, error) {
 	switch answer.Header.Type {
 	case dnsmessage.TypeA:
 		if a, ok := answer.Body.(*dnsmessage.AResource); ok {

conn_test.go

@@ -672,6 +672,73 @@ func TestQueryRespectClose(t *testing.T) {
 	}
 }
 
+func testResourceParsing(t *testing.T, echoQuery bool) {
+	lookForIP := func(msg dnsmessage.Message, expectedIP []byte, t *testing.T) {
+		actualAddr, err := addrFromAnswer(msg.Answers[0])
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		if echoQuery {
+			if len(msg.Questions) == 0 {
+				t.Fatal("Echoed query not included in answer")
+			}
+		} else {
+			if len(msg.Questions) > 0 {
+				t.Fatal("Echoed query erroneously included in answer")
+			}
+		}
+
+		if !bytes.Equal(actualAddr.AsSlice(), expectedIP) {
+			t.Fatalf("Expected(%v) and Actual(%v) IP don't match", expectedIP, actualAddr)
+		}
+	}
+
+	name := "test-server."
+
+	config := &Config{
+		DoNotEchoQueryWithAnswer: !echoQuery,
+	}
+
+	t.Run("A Record", func(t *testing.T) {
+		answer, err := createAnswer(1, dnsmessage.Question{
+			Name: dnsmessage.MustNewName(name),
+			Type: dnsmessage.TypeA,
+		}, mustAddr(net.IP{127, 0, 0, 1}), config)
+		if err != nil {
+			t.Fatal(err)
+		}
+		lookForIP(answer, []byte{127, 0, 0, 1}, t)
+	})
+
+	t.Run("AAAA Record", func(t *testing.T) {
+		answer, err := createAnswer(1, dnsmessage.Question{
+			Name: dnsmessage.MustNewName(name),
+			Type: dnsmessage.TypeAAAA,
+		}, netip.MustParseAddr("::1"), config)
+		if err != nil {
+			t.Fatal(err)
+		}
+		lookForIP(answer, []byte{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1}, t)
+	})
+}
+
+func TestResourceParsingWithEchoedQuery(t *testing.T) {
+	testResourceParsing(t, true)
+}
+
+func TestResourceParsingWithoutEchoedQuery(t *testing.T) {
+	testResourceParsing(t, false)
+}
+
+func mustAddr(ip net.IP) netip.Addr {
+	addr, ok := netip.AddrFromSlice(ip)
+	if !ok {
+		panic(ipToAddrError{ip})
+	}
+	return addr
+}
+
 func TestIPToBytes(t *testing.T) {
 	expectedIP := []byte{127, 0, 0, 1}
 	actualAddr4, err := ipv4ToBytes(netip.MustParseAddr("127.0.0.1"))