Refactor ETag checking in transports

transport/azure/azure.go

@@ -18,6 +18,7 @@ import (
 	"github.com/imgproxy/imgproxy/v3/config"
 	"github.com/imgproxy/imgproxy/v3/ctxreader"
 	"github.com/imgproxy/imgproxy/v3/httprange"
+	"github.com/imgproxy/imgproxy/v3/transport/notmodified"
 )
 
 type transport struct {
@@ -120,22 +121,15 @@ func (t transport) RoundTrip(req *http.Request) (*http.Response, error) {
 	}
 
 	if config.ETagEnabled && result.ETag != nil {
-		azETag := string(*result.ETag)
+		etag := string(*result.ETag)
-		header.Set("ETag", azETag)
+		header.Set("ETag", etag)
-
-		if etag := req.Header.Get("If-None-Match"); len(etag) > 0 && azETag == etag {
-			return &http.Response{
-				StatusCode:    http.StatusNotModified,
-				Proto:         "HTTP/1.0",
-				ProtoMajor:    1,
-				ProtoMinor:    0,
-				Header:        header,
-				ContentLength: 0,
-				Body:          nil,
-				Close:         false,
-				Request:       req,
-			}, nil
 	}
+
+	if resp := notmodified.Response(req, header); resp != nil {
+		if result.Body != nil {
+			result.Body.Close()
+		}
+		return resp, nil
 	}
 
 	header.Set("Accept-Ranges", "bytes")

transport/fs/fs.go

@@ -16,6 +16,7 @@ import (
 	"github.com/imgproxy/imgproxy/v3/config"
 	"github.com/imgproxy/imgproxy/v3/ctxreader"
 	"github.com/imgproxy/imgproxy/v3/httprange"
+	"github.com/imgproxy/imgproxy/v3/transport/notmodified"
 )
 
 type transport struct {
@@ -73,27 +74,18 @@ func (t transport) RoundTrip(req *http.Request) (resp *http.Response, err error)
 		body = &fileLimiter{f: f, left: int(size)}
 		header.Set("Content-Range", fmt.Sprintf("bytes %d-%d/%d", start, end, fi.Size()))
 
-	case config.ETagEnabled:
+	default:
+		if config.ETagEnabled {
 			etag := BuildEtag(req.URL.Path, fi)
 			header.Set("ETag", etag)
-
-		if etag == req.Header.Get("If-None-Match") {
-			f.Close()
-
-			return &http.Response{
-				StatusCode:    http.StatusNotModified,
-				Proto:         "HTTP/1.0",
-				ProtoMajor:    1,
-				ProtoMinor:    0,
-				Header:        header,
-				ContentLength: 0,
-				Body:          nil,
-				Close:         false,
-				Request:       req,
-			}, nil
 		}
 	}
 
+	if resp := notmodified.Response(req, header); resp != nil {
+		f.Close()
+		return resp, nil
+	}
+
 	header.Set("Accept-Ranges", "bytes")
 	header.Set("Content-Length", strconv.Itoa(int(size)))
 

transport/gcs/gcs.go

@@ -14,6 +14,7 @@ import (
 	"github.com/imgproxy/imgproxy/v3/config"
 	"github.com/imgproxy/imgproxy/v3/ctxreader"
 	"github.com/imgproxy/imgproxy/v3/httprange"
+	"github.com/imgproxy/imgproxy/v3/transport/notmodified"
 )
 
 // For tests
@@ -104,20 +105,10 @@ func (t transport) RoundTrip(req *http.Request) (*http.Response, error) {
 				return handleError(req, err)
 			}
 			header.Set("ETag", attrs.Etag)
-
-			if etag := req.Header.Get("If-None-Match"); len(etag) > 0 && attrs.Etag == etag {
-				return &http.Response{
-					StatusCode:    http.StatusNotModified,
-					Proto:         "HTTP/1.0",
-					ProtoMajor:    1,
-					ProtoMinor:    0,
-					Header:        header,
-					ContentLength: 0,
-					Body:          nil,
-					Close:         false,
-					Request:       req,
-				}, nil
 		}
+
+		if resp := notmodified.Response(req, header); resp != nil {
+			return resp, nil
 		}
 
 		var err error

transport/notmodified/notmodified.go

@@ -0,0 +1,34 @@
+package notmodified
+
+import (
+	"net/http"
+
+	"github.com/imgproxy/imgproxy/v3/config"
+)
+
+func Response(req *http.Request, header http.Header) *http.Response {
+	if config.ETagEnabled {
+		etag := header.Get("ETag")
+		ifNoneMatch := req.Header.Get("If-None-Match")
+
+		if len(ifNoneMatch) > 0 && ifNoneMatch == etag {
+			return response(req, header)
+		}
+	}
+
+	return nil
+}
+
+func response(req *http.Request, header http.Header) *http.Response {
+	return &http.Response{
+		StatusCode:    http.StatusNotModified,
+		Proto:         "HTTP/1.0",
+		ProtoMajor:    1,
+		ProtoMinor:    0,
+		Header:        header,
+		ContentLength: 0,
+		Body:          nil,
+		Close:         false,
+		Request:       req,
+	}
+}

transport/swift/swift.go

@@ -13,6 +13,7 @@ import (
 
 	"github.com/imgproxy/imgproxy/v3/config"
 	"github.com/imgproxy/imgproxy/v3/ctxreader"
+	"github.com/imgproxy/imgproxy/v3/transport/notmodified"
 )
 
 type transport struct {
@@ -76,22 +77,11 @@ func (t transport) RoundTrip(req *http.Request) (resp *http.Response, err error)
 	if config.ETagEnabled {
 		if etag, ok := objectHeaders["Etag"]; ok {
 			header.Set("ETag", etag)
-
-			if len(etag) > 0 && etag == req.Header.Get("If-None-Match") {
-				object.Close()
-
-				return &http.Response{
-					StatusCode:    http.StatusNotModified,
-					Proto:         "HTTP/1.0",
-					ProtoMajor:    1,
-					ProtoMinor:    0,
-					Header:        header,
-					ContentLength: 0,
-					Body:          nil,
-					Close:         false,
-					Request:       req,
-				}, nil
 		}
+
+		if resp := notmodified.Response(req, header); resp != nil {
+			object.Close()
+			return resp, nil
 		}
 	}