Make image proxy configurable

Adds IMAGE_PROXY configuration setting to change image proxy filter behaviour:

- none = No proxy
- http-only = Proxy only non-HTTPS images (default)
- all = Proxy everything

filter/image_proxy_filter.go

@@ -8,6 +8,7 @@ import (
 	"encoding/base64"
 	"strings"
 
+	"github.com/miniflux/miniflux/config"
 	"github.com/miniflux/miniflux/http/route"
 	"github.com/miniflux/miniflux/url"
 
@@ -15,8 +16,13 @@ import (
 	"github.com/gorilla/mux"
 )
 
-// ImageProxyFilter rewrites image tag URLs without HTTPS to local proxy URL
-func ImageProxyFilter(router *mux.Router, data string) string {
+// ImageProxyFilter rewrites image tag URLs to local proxy URL (by default only non-HTTPS URLs)
+func ImageProxyFilter(router *mux.Router, cfg *config.Config, data string) string {
+	proxyImages := cfg.ProxyImages()
+	if proxyImages == "none" {
+		return data
+	}
+
 	doc, err := goquery.NewDocumentFromReader(strings.NewReader(data))
 	if err != nil {
 		return data
@@ -24,7 +30,7 @@ func ImageProxyFilter(router *mux.Router, data string) string {
 
 	doc.Find("img").Each(func(i int, img *goquery.Selection) {
 		if srcAttr, ok := img.Attr("src"); ok {
-			if !url.IsHTTPS(srcAttr) {
+			if proxyImages == "all" || !url.IsHTTPS(srcAttr) {
 				img.SetAttr("src", Proxify(router, srcAttr))
 			}
 		}

filter/image_proxy_filter_test.go

@@ -6,17 +6,24 @@ package filter
 
 import (
 	"net/http"
+	"os"
 	"testing"
 
+	"github.com/miniflux/miniflux/config"
+
 	"github.com/gorilla/mux"
 )
 
-func TestProxyFilterWithHttp(t *testing.T) {
+func TestProxyFilterWithHttpDefault(t *testing.T) {
+	os.Clearenv()
+	os.Setenv("PROXY_IMAGES", "http-only")
+	c := config.NewConfig()
+
 	r := mux.NewRouter()
 	r.HandleFunc("/proxy/{encodedURL}", func(w http.ResponseWriter, r *http.Request) {}).Name("proxy")
 
 	input := `<p><img src="http://website/folder/image.png" alt="Test"/></p>`
-	output := ImageProxyFilter(r, input)
+	output := ImageProxyFilter(r, c, input)
 	expected := `<p><img src="/proxy/aHR0cDovL3dlYnNpdGUvZm9sZGVyL2ltYWdlLnBuZw==" alt="Test"/></p>`
 
 	if expected != output {
@@ -24,12 +31,118 @@ func TestProxyFilterWithHttp(t *testing.T) {
 	}
 }
 
-func TestProxyFilterWithHttps(t *testing.T) {
+func TestProxyFilterWithHttpsDefault(t *testing.T) {
+	os.Clearenv()
+	os.Setenv("PROXY_IMAGES", "http-only")
+	c := config.NewConfig()
+
 	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 := ImageProxyFilter(r, input)
+	output := ImageProxyFilter(r, c, input)
+	expected := `<p><img src="https://website/folder/image.png" alt="Test"/></p>`
+
+	if expected != output {
+		t.Errorf(`Not expected output: got "%s" instead of "%s"`, output, expected)
+	}
+}
+
+func TestProxyFilterWithHttpNever(t *testing.T) {
+	os.Clearenv()
+	os.Setenv("PROXY_IMAGES", "none")
+	c := config.NewConfig()
+
+	r := mux.NewRouter()
+	r.HandleFunc("/proxy/{encodedURL}", func(w http.ResponseWriter, r *http.Request) {}).Name("proxy")
+
+	input := `<p><img src="http://website/folder/image.png" alt="Test"/></p>`
+	output := ImageProxyFilter(r, c, input)
+	expected := input
+
+	if expected != output {
+		t.Errorf(`Not expected output: got "%s" instead of "%s"`, output, expected)
+	}
+}
+
+func TestProxyFilterWithHttpsNever(t *testing.T) {
+	os.Clearenv()
+	os.Setenv("PROXY_IMAGES", "none")
+	c := config.NewConfig()
+
+	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 := ImageProxyFilter(r, c, input)
+	expected := input
+
+	if expected != output {
+		t.Errorf(`Not expected output: got "%s" instead of "%s"`, output, expected)
+	}
+}
+
+func TestProxyFilterWithHttpAlways(t *testing.T) {
+	os.Clearenv()
+	os.Setenv("PROXY_IMAGES", "all")
+	c := config.NewConfig()
+
+	r := mux.NewRouter()
+	r.HandleFunc("/proxy/{encodedURL}", func(w http.ResponseWriter, r *http.Request) {}).Name("proxy")
+
+	input := `<p><img src="http://website/folder/image.png" alt="Test"/></p>`
+	output := ImageProxyFilter(r, c, input)
+	expected := `<p><img src="/proxy/aHR0cDovL3dlYnNpdGUvZm9sZGVyL2ltYWdlLnBuZw==" alt="Test"/></p>`
+
+	if expected != output {
+		t.Errorf(`Not expected output: got "%s" instead of "%s"`, output, expected)
+	}
+}
+
+func TestProxyFilterWithHttpsAlways(t *testing.T) {
+	os.Clearenv()
+	os.Setenv("PROXY_IMAGES", "all")
+	c := config.NewConfig()
+
+	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 := ImageProxyFilter(r, c, input)
+	expected := `<p><img src="/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")
+	c := config.NewConfig()
+
+	r := mux.NewRouter()
+	r.HandleFunc("/proxy/{encodedURL}", func(w http.ResponseWriter, r *http.Request) {}).Name("proxy")
+
+	input := `<p><img src="http://website/folder/image.png" alt="Test"/></p>`
+	output := ImageProxyFilter(r, c, input)
+	expected := `<p><img src="/proxy/aHR0cDovL3dlYnNpdGUvZm9sZGVyL2ltYWdlLnBuZw==" alt="Test"/></p>`
+
+	if expected != output {
+		t.Errorf(`Not expected output: got "%s" instead of "%s"`, output, expected)
+	}
+}
+
+func TestProxyFilterWithHttpsInvalid(t *testing.T) {
+	os.Clearenv()
+	os.Setenv("PROXY_IMAGES", "invalid")
+	c := config.NewConfig()
+
+	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 := ImageProxyFilter(r, c, input)
 	expected := `<p><img src="https://website/folder/image.png" alt="Test"/></p>`
 
 	if expected != output {