Fix caching behavior

client.go

@@ -84,7 +84,7 @@ func (c *Client) Exchange(ctx context.Context, transport Transport, message *dns
 }
 
 func (c *Client) ExchangeWithResponseCheck(ctx context.Context, transport Transport, message *dns.Msg, strategy DomainStrategy, responseChecker func(response *dns.Msg) bool) (*dns.Msg, error) {
-	if len(message.Question) != 1 {
+	if len(message.Question) == 0 {
 		if c.logger != nil {
 			c.logger.WarnContext(ctx, "bad question size: ", len(message.Question))
 		}
@@ -99,7 +99,15 @@ func (c *Client) ExchangeWithResponseCheck(ctx context.Context, transport Transp
 		return &responseMessage, nil
 	}
 	question := message.Question[0]
-	disableCache := c.disableCache || DisableCacheFromContext(ctx)
+	clientSubnet, clientSubnetLoaded := ClientSubnetFromContext(ctx)
+	if clientSubnetLoaded {
+		SetClientSubnet(message, clientSubnet, true)
+	}
+	isSimpleRequest := len(message.Question) == 1 &&
+		len(message.Ns) == 0 &&
+		len(message.Extra) == 0 &&
+		!clientSubnetLoaded
+	disableCache := isSimpleRequest || c.disableCache || DisableCacheFromContext(ctx)
 	if !disableCache {
 		response, ttl := c.loadResponse(question, transport)
 		if response != nil {
@@ -129,15 +137,11 @@ func (c *Client) ExchangeWithResponseCheck(ctx context.Context, transport Transp
 		return nil, ErrNoRawSupport
 	}
 	messageId := message.Id
-	contextTransport, loaded := transportNameFromContext(ctx)
-	if loaded && transport.Name() == contextTransport {
+	contextTransport, clientSubnetLoaded := transportNameFromContext(ctx)
+	if clientSubnetLoaded && transport.Name() == contextTransport {
 		return nil, E.New("DNS query loopback in transport[", contextTransport, "]")
 	}
 	ctx = contextWithTransportName(ctx, transport.Name())
-	clientSubnet, loaded := ClientSubnetFromContext(ctx)
-	if loaded {
-		SetClientSubnet(message, clientSubnet, true)
-	}
 	if responseChecker != nil && c.rdrc != nil {
 		rejected := c.rdrc.LoadRDRC(transport.Name(), question.Name)
 		if rejected {
@@ -170,13 +174,11 @@ func (c *Client) ExchangeWithResponseCheck(ctx context.Context, transport Transp
 			record.Header().Ttl = uint32(timeToLive)
 		}
 	}
-	logExchangedResponse(c.logger, ctx, response, timeToLive)
-
 	response.Id = messageId
 	if !disableCache {
 		c.storeCache(transport, question, response, timeToLive)
 	}
-
+	logExchangedResponse(c.logger, ctx, response, timeToLive)
 	return response, err
 }
 

go.mod

@@ -7,6 +7,7 @@ require (
 	github.com/sagernet/quic-go v0.40.1
 	github.com/sagernet/sing v0.3.2
 	github.com/stretchr/testify v1.8.4
+	golang.org/x/exp v0.0.0-20240222234643-814bf88cf225
 )
 
 require (
@@ -17,12 +18,11 @@ require (
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/quic-go/qpack v0.4.0 // indirect
 	github.com/quic-go/qtls-go1-20 v0.4.1 // indirect
-	golang.org/x/crypto v0.18.0 // indirect
-	golang.org/x/exp v0.0.0-20231226003508-02704c960a9b // indirect
-	golang.org/x/mod v0.14.0 // indirect
-	golang.org/x/net v0.20.0 // indirect
+	golang.org/x/crypto v0.19.0 // indirect
+	golang.org/x/mod v0.15.0 // indirect
+	golang.org/x/net v0.21.0 // indirect
 	golang.org/x/sys v0.17.0 // indirect
 	golang.org/x/text v0.14.0 // indirect
-	golang.org/x/tools v0.17.0 // indirect
+	golang.org/x/tools v0.18.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )

go.sum

@@ -27,21 +27,21 @@ github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+
 github.com/stretchr/testify v1.6.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.8.4 h1:CcVxjf3Q8PM0mHUKJCdn+eZZtm5yQwehR5yeSVQQcUk=
 github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
-golang.org/x/crypto v0.18.0 h1:PGVlW0xEltQnzFZ55hkuX5+KLyrMYhHld1YHO4AKcdc=
-golang.org/x/crypto v0.18.0/go.mod h1:R0j02AL6hcrfOiy9T4ZYp/rcWeMxM3L6QYxlOuEG1mg=
-golang.org/x/exp v0.0.0-20231226003508-02704c960a9b h1:kLiC65FbiHWFAOu+lxwNPujcsl8VYyTYYEZnsOO1WK4=
-golang.org/x/exp v0.0.0-20231226003508-02704c960a9b/go.mod h1:iRJReGqOEeBhDZGkGbynYwcHlctCvnjTYIamk7uXpHI=
-golang.org/x/mod v0.14.0 h1:dGoOF9QVLYng8IHTm7BAyWqCqSheQ5pYWGhzW00YJr0=
-golang.org/x/mod v0.14.0/go.mod h1:hTbmBsO62+eylJbnUtE2MGJUyE7QWk4xUqPFrRgJ+7c=
-golang.org/x/net v0.20.0 h1:aCL9BSgETF1k+blQaYUBx9hJ9LOGP3gAVemcZlf1Kpo=
-golang.org/x/net v0.20.0/go.mod h1:z8BVo6PvndSri0LbOE3hAn0apkU+1YvI6E70E9jsnvY=
+golang.org/x/crypto v0.19.0 h1:ENy+Az/9Y1vSrlrvBSyna3PITt4tiZLf7sgCjZBX7Wo=
+golang.org/x/crypto v0.19.0/go.mod h1:Iy9bg/ha4yyC70EfRS8jz+B6ybOBKMaSxLj6P6oBDfU=
+golang.org/x/exp v0.0.0-20240222234643-814bf88cf225 h1:LfspQV/FYTatPTr/3HzIcmiUFH7PGP+OQ6mgDYo3yuQ=
+golang.org/x/exp v0.0.0-20240222234643-814bf88cf225/go.mod h1:CxmFvTBINI24O/j8iY7H1xHzx2i4OsyguNBmN/uPtqc=
+golang.org/x/mod v0.15.0 h1:SernR4v+D55NyBH2QiEQrlBAnj1ECL6AGrA5+dPaMY8=
+golang.org/x/mod v0.15.0/go.mod h1:hTbmBsO62+eylJbnUtE2MGJUyE7QWk4xUqPFrRgJ+7c=
+golang.org/x/net v0.21.0 h1:AQyQV4dYCvJ7vGmJyKki9+PBdyvhkSd8EIx/qb0AYv4=
+golang.org/x/net v0.21.0/go.mod h1:bIjVDfnllIU7BJ2DNgfnXvpSvtn8VRwhlsaeUTyUS44=
 golang.org/x/sync v0.6.0 h1:5BMeUDZ7vkXGfEr1x9B4bRcTH4lpkTkpdh0T/J+qjbQ=
 golang.org/x/sys v0.17.0 h1:25cE3gD+tdBA7lp7QfhuV+rJiE9YXTcS3VG1SqssI/Y=
 golang.org/x/sys v0.17.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/text v0.14.0 h1:ScX5w1eTa3QqT8oi6+ziP7dTV1S2+ALU0bI+0zXKWiQ=
 golang.org/x/text v0.14.0/go.mod h1:18ZOQIKpY8NJVqYksKHtTdi31H5itFRjB5/qKTNYzSU=
-golang.org/x/tools v0.17.0 h1:FvmRgNOcs3kOa+T20R1uhfP9F6HgG2mfxDv1vrx1Htc=
-golang.org/x/tools v0.17.0/go.mod h1:xsh6VxdV005rRVaS6SSAf9oiAqljS7UZUacMZ8Bnsps=
+golang.org/x/tools v0.18.0 h1:k8NLag8AGHnn+PHbl7g43CtqZAwG60vZkLqgyZgIHgQ=
+golang.org/x/tools v0.18.0/go.mod h1:GL7B4CwcLLeo59yx/9UWWuNOW1n3VZ4f5axWfML7Lcg=
 google.golang.org/protobuf v1.28.0 h1:w43yiav+6bVFTBQFZX0r7ipe9JQ1QsbMgHwbBziscLw=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=