Allow setting a custom image proxy URL

proxy/image_proxy_test.go

@@ -151,6 +151,30 @@ func TestProxyFilterWithHttpsAlways(t *testing.T) {
 	}
 }
 
+func TestProxyFilterWithHttpsAlwaysAndCustomProxyServer(t *testing.T) {
+	os.Clearenv()
+	os.Setenv("PROXY_IMAGES", "all")
+	os.Setenv("PROXY_IMAGE_URL", "https://proxy-example/proxy")
+
+	var err error
+	parser := config.NewParser()
+	config.Opts, err = parser.ParseEnvironmentVariables()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %v`, err)
+	}
+
+	r := mux.NewRouter()
+	r.HandleFunc("/proxy/{encodedURL}", func(w http.ResponseWriter, r *http.Request) {}).Name("proxy")
+
+	input := `<p><img src="https://website/folder/image.png" alt="Test"/></p>`
+	output := ImageProxyRewriter(r, input)
+	expected := `<p><img src="https://proxy-example/proxy/aHR0cHM6Ly93ZWJzaXRlL2ZvbGRlci9pbWFnZS5wbmc=" alt="Test"/></p>`
+
+	if expected != output {
+		t.Errorf(`Not expected output: got "%s" instead of "%s"`, output, expected)
+	}
+}
+
 func TestProxyFilterWithHttpInvalid(t *testing.T) {
 	os.Clearenv()
 	os.Setenv("PROXY_IMAGES", "invalid")

proxy/proxy.go

@@ -6,16 +6,32 @@ package proxy // import "miniflux.app/proxy"
 
 import (
 	"encoding/base64"
+	"net/url"
+	"path"
 
 	"miniflux.app/http/route"
 
 	"github.com/gorilla/mux"
+
+	"miniflux.app/config"
 )
 
 // ProxifyURL generates an URL for a proxified resource.
 func ProxifyURL(router *mux.Router, link string) string {
 	if link != "" {
-		return route.Path(router, "proxy", "encodedURL", base64.URLEncoding.EncodeToString([]byte(link)))
+		proxyImageUrl := config.Opts.ProxyImageUrl()
+
+		if proxyImageUrl == "" {
+			return route.Path(router, "proxy", "encodedURL", base64.URLEncoding.EncodeToString([]byte(link)))
+		}
+
+		proxyUrl, err := url.Parse(proxyImageUrl)
+		if err != nil {
+			return ""
+		}
+
+		proxyUrl.Path = path.Join(proxyUrl.Path, base64.URLEncoding.EncodeToString([]byte(link)))
+		return proxyUrl.String()
 	}
 	return ""
 }