Proxying Accept-Encoding and Accept headers for /asis

img/loader/http.go

@@ -33,7 +33,7 @@ var client = &http.Client{
 	},
 }
 
-func (r *Http) Load(url string, _ context.Context) (*img.Image, error) {
+func (r *Http) Load(url string, ctx context.Context) (*img.Image, error) {
 	req, err := http.NewRequest("GET", url, nil)
 	if err != nil {
 		return nil, err
@@ -44,6 +44,14 @@ func (r *Http) Load(url string, _ context.Context) (*img.Image, error) {
 		}
 	}
 
+	if moreHeaders, ok := headerFromContext(ctx); ok {
+		for k, v := range *moreHeaders {
+			for _, headerVal := range v {
+				req.Header.Add(k, headerVal)
+			}
+		}
+	}
+
 	resp, err := client.Do(req)
 	if err != nil {
 		return nil, err
@@ -70,3 +78,14 @@ func (r *Http) Load(url string, _ context.Context) (*img.Image, error) {
 		MimeType: contentType,
 	}, nil
 }
+
+type headersKey int
+
+func NewContextWithHeaders(ctx context.Context, headers *http.Header) context.Context {
+	return context.WithValue(ctx, headersKey(0), headers)
+}
+
+func headerFromContext(ctx context.Context) (*http.Header, bool) {
+	header, ok := ctx.Value(headersKey(0)).(*http.Header)
+	return header, ok
+}

img/service.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"github.com/Pixboost/transformimgs/v8/img/loader"
 	"github.com/dooman87/glogi"
 	"github.com/gorilla/mux"
 	"net/http"
@@ -192,7 +193,10 @@ func (r *Service) AsIs(resp http.ResponseWriter, req *http.Request) {
 
 	Log.Printf("Requested image %s as is\n", imgUrl)
 
-	result, err := r.Loader.Load(imgUrl, req.Context())
+	var proxyHeaders http.Header
+	proxyHeaders.Add("Accept", req.Header.Get("Accept"))
+	proxyHeaders.Add("Accept-Encoding", req.Header.Get("Accept-Encoding"))
+	result, err := r.Loader.Load(imgUrl, loader.NewContextWithHeaders(req.Context(), &proxyHeaders))
 
 	if err != nil {
 		sendError(resp, err)