Add an upstream channel for PNG queries

internal/config/config.go

@@ -62,6 +62,10 @@ type Uplink struct {
 	// for all other queries.
 	Address3 string `yaml:"address3,omitempty"`
 
+	// Address4 contains address of the uplink server in form IP:PORT
+	// for PNG queries.
+	Address4 string `yaml:"address4,omitempty"`
+
 	// Timeout for upstream queries.
 	Timeout int `yaml:"timeout,omitempty"`
 
@@ -152,6 +156,7 @@ func Default() *Config {
 			Address1:         "127.0.0.1:9002",
 			Address2:         "127.0.0.1:9002",
 			Address3:         "127.0.0.1:9002",
+			Address4:         "127.0.0.1:9002",
 			Timeout:          30,
 			PrefetchInterval: 300,
 		},

internal/processor/j1.go

@@ -9,7 +9,7 @@ import (
 	"time"
 )
 
-func getAny(req *http.Request, tr1, tr2, tr3 *http.Transport) (*ResponseWithHeader, error) {
+func getAny(req *http.Request, tr1, tr2, tr3, tr4 *http.Transport) (*ResponseWithHeader, error) {
 	uri := strings.ReplaceAll(req.URL.RequestURI(), "%", "%25")
 
 	u, err := url.Parse(uri)
@@ -28,6 +28,10 @@ func getAny(req *http.Request, tr1, tr2, tr3 *http.Transport) (*ResponseWithHead
 	// log.Println(req.URL.Query())
 	// log.Println()
 
+	if checkURLForPNG(req) {
+		return getDefault(req, tr4)
+	}
+
 	return getDefault(req, tr3)
 }
 
@@ -87,3 +91,8 @@ func getUpstream(req *http.Request, transport *http.Transport) (*ResponseWithHea
 		StatusCode: res.StatusCode,
 	}, nil
 }
+
+func checkURLForPNG(r *http.Request) bool {
+	url := r.URL.String()
+	return strings.Contains(url, ".png") && !strings.Contains(url, "/files/")
+}

internal/processor/processor.go

@@ -60,6 +60,7 @@ type RequestProcessor struct {
 	upstreamTransport1 *http.Transport
 	upstreamTransport2 *http.Transport
 	upstreamTransport3 *http.Transport
+	upstreamTransport4 *http.Transport
 	config             *config.Config
 	geoIPCache         *geoip.Cache
 	geoLocation        *geoloc.Cache
@@ -93,6 +94,11 @@ func NewRequestProcessor(config *config.Config) (*RequestProcessor, error) {
 			return dialer.DialContext(ctx, network, config.Uplink.Address3)
 		},
 	}
+	transport4 := &http.Transport{
+		DialContext: func(ctx context.Context, network, _ string) (net.Conn, error) {
+			return dialer.DialContext(ctx, network, config.Uplink.Address4)
+		},
+	}
 
 	geoCache, err := geoip.NewCache(config)
 	if err != nil {
@@ -110,6 +116,7 @@ func NewRequestProcessor(config *config.Config) (*RequestProcessor, error) {
 		upstreamTransport1: transport1,
 		upstreamTransport2: transport2,
 		upstreamTransport3: transport3,
+		upstreamTransport4: transport4,
 		config:             config,
 		geoIPCache:         geoCache,
 		geoLocation:        geoLocation,
@@ -156,7 +163,7 @@ func (rp *RequestProcessor) ProcessRequest(r *http.Request) (*ResponseWithHeader
 	if dontCache(r) {
 		rp.stats.Inc("uncached")
 
-		return getAny(r, rp.upstreamTransport1, rp.upstreamTransport2, rp.upstreamTransport3)
+		return getAny(r, rp.upstreamTransport1, rp.upstreamTransport2, rp.upstreamTransport3, rp.upstreamTransport4)
 	}
 
 	// processing cached request
@@ -247,7 +254,7 @@ func (rp *RequestProcessor) processUncachedRequest(r *http.Request) (*ResponseWi
 		rp.stats.Inc("geoip")
 	}
 
-	response, err = getAny(r, rp.upstreamTransport1, rp.upstreamTransport2, rp.upstreamTransport3)
+	response, err = getAny(r, rp.upstreamTransport1, rp.upstreamTransport2, rp.upstreamTransport3, rp.upstreamTransport4)
 	if err != nil {
 		return nil, err
 	}