Support HEAD requests for artwork endpoints

src/webserver/apiv1_endpoints.go

@@ -19,12 +19,16 @@ const (
 // It is an uri_path => list of HTTP methods map.
 var APIv1Methods map[string][]string = map[string][]string{
 	APIv1EndpointFile:           {http.MethodGet},
-	APIv1EndpointAlbumArtwork:   {http.MethodGet, http.MethodPut, http.MethodDelete},
 	APIv1EndpointDownloadAlbum:  {http.MethodGet},
-	APIv1EndpointArtistImage:    {http.MethodGet, http.MethodPut, http.MethodDelete},
 	APIv1EndpointBrowse:         {http.MethodGet},
 	APIv1EndpointSearchWithPath: {http.MethodGet},
 	APIv1EndpointSearch:         {http.MethodGet},
 	APIv1EndpointLoginToken:     {http.MethodPost},
 	APIv1EndpointRegisterToken:  {http.MethodPost},
+	APIv1EndpointArtistImage: {
+		http.MethodGet, http.MethodHead, http.MethodPut, http.MethodDelete,
+	},
+	APIv1EndpointAlbumArtwork: {
+		http.MethodGet, http.MethodHead, http.MethodPut, http.MethodDelete,
+	},
 }

src/webserver/handler_album_artwork.go

@@ -77,6 +77,10 @@ func (aah AlbumArtworkHandler) Find(
 
 	if err == library.ErrArtworkNotFound || os.IsNotExist(err) {
 		writer.WriteHeader(http.StatusNotFound)
+		if req.Method == http.MethodHead {
+			return nil
+		}
+
 		notFoundImage, err := aah.rootFS.Open(aah.notFoundPath)
 		if err == nil {
 			defer notFoundImage.Close()
@@ -96,8 +100,13 @@ func (aah AlbumArtworkHandler) Find(
 	defer imgReader.Close()
 
 	writer.Header().Set("Cache-Control", "max-age=604800")
-	_, err = io.Copy(writer, imgReader)
+	if req.Method == http.MethodHead {
+		n, _ := io.Copy(io.Discard, imgReader)
+		writer.Header().Set("Content-Length", strconv.FormatInt(n, 10))
+		return nil
+	}
 
+	_, err = io.Copy(writer, imgReader)
 	if err != nil {
 		log.Printf("еrror sending HTTP data for artwork %d: %s", id, err)
 	}

src/webserver/handler_album_artwork_test.go

@@ -8,6 +8,7 @@ import (
 	"io"
 	"net/http"
 	"net/http/httptest"
+	"strconv"
 	"strings"
 	"testing"
 	"testing/fstest"
@@ -19,9 +20,9 @@ import (
 	"github.com/ironsmile/euterpe/src/webserver"
 )
 
-// TestAlbumArtworkHandlerGET makes sure the artwork handler is processing the HTTP
+// TestAlbumArtworkHandler makes sure the artwork handler is processing the HTTP
 // request correctly and sending the expected arguments to its artwork manager.
-func TestAlbumArtworkHandlerGET(t *testing.T) {
+func TestAlbumArtworkHandler(t *testing.T) {
 	imgBytesOriginal := []byte("album 321 image original")
 	imgBytesSmall := []byte("album 321 image small")
 
@@ -155,6 +156,26 @@ func TestAlbumArtworkHandlerGET(t *testing.T) {
 			respString,
 		)
 	}
+
+	// Test the HEAD request. It should return the Content-Length and 200 for
+	// images which are present.
+	resp = httptest.NewRecorder()
+	req = httptest.NewRequest(http.MethodHead, "/v1/album/321/artwork?size=small", nil)
+	handler.ServeHTTP(resp, req)
+
+	if resp.Code != http.StatusOK {
+		t.Errorf("HEAD small: expected code %d but got %d", http.StatusOK, resp.Code)
+	}
+
+	clExpected := strconv.FormatInt(int64(len(imgBytesSmall)), 10)
+	if cl := resp.Result().Header.Get("Content-Length"); clExpected != cl {
+		t.Errorf("HEAD small: expected Content-Length `%s` but got `%s`",
+			clExpected, cl)
+	}
+	respBodySize, err := io.Copy(io.Discard, resp.Result().Body)
+	if err != nil || respBodySize != 0 {
+		t.Errorf("HEAD response should have empty body")
+	}
 }
 
 // TestAlbumArtworkHandlerDELETE tests what happens when artwork is removed.

src/webserver/handler_artist_images.go

@@ -74,6 +74,10 @@ func (aih ArtstImageHandler) Find(
 
 	if err == library.ErrArtworkNotFound || os.IsNotExist(err) {
 		writer.WriteHeader(http.StatusNotFound)
+		if req.Method == http.MethodHead {
+			return nil
+		}
+
 		fmt.Fprintln(writer, "404 image not found")
 		return nil
 	}
@@ -86,8 +90,13 @@ func (aih ArtstImageHandler) Find(
 	defer imgReader.Close()
 
 	writer.Header().Set("Cache-Control", "max-age=604800")
-	_, err = io.Copy(writer, imgReader)
+	if req.Method == http.MethodHead {
+		n, _ := io.Copy(io.Discard, imgReader)
+		writer.Header().Set("Content-Length", strconv.FormatInt(n, 10))
+		return nil
+	}
 
+	_, err = io.Copy(writer, imgReader)
 	if err != nil {
 		log.Printf("еrror sending HTTP data for artwork %d: %s", id, err)
 	}

src/webserver/handler_artist_images_test.go

@@ -8,6 +8,7 @@ import (
 	"io"
 	"net/http"
 	"net/http/httptest"
+	"strconv"
 	"strings"
 	"testing"
 
@@ -17,9 +18,9 @@ import (
 	"github.com/ironsmile/euterpe/src/webserver"
 )
 
-// TestArtstImageHandlerGET checks that the HTTP handler for GET requests is parsing
+// TestArtstImageHandler checks that the HTTP handler for GET requests is parsing
 // its arguments as expected and responds with the image found by its image manager.
-func TestArtstImageHandlerGET(t *testing.T) {
+func TestArtstImageHandler(t *testing.T) {
 	imgBytesOriginal := []byte("artist 321 image original")
 	imgBytesSmall := []byte("artist 321 image small")
 
@@ -128,6 +129,25 @@ func TestArtstImageHandlerGET(t *testing.T) {
 			respString,
 		)
 	}
+
+	// Test the HEDE reqeuest.
+	resp = httptest.NewRecorder()
+	req = httptest.NewRequest(http.MethodHead, "/v1/artist/321/image?size=small", nil)
+	handler.ServeHTTP(resp, req)
+
+	if resp.Code != http.StatusOK {
+		t.Errorf("HEAD small: expected code %d but got %d", http.StatusOK, resp.Code)
+	}
+
+	clExpected := strconv.FormatInt(int64(len(imgBytesSmall)), 10)
+	if cl := resp.Result().Header.Get("Content-Length"); clExpected != cl {
+		t.Errorf("HEAD Dsmall: expected image `%s` but got `%s`",
+			clExpected, cl)
+	}
+	respBodySize, err := io.Copy(io.Discard, resp.Result().Body)
+	if err != nil || respBodySize != 0 {
+		t.Errorf("HEAD response should have empty body")
+	}
 }
 
 // TestArtstImageHandlerDELETE tests what happens when artwork is removed.

src/webserver/subsonic/index.go

@@ -89,7 +89,7 @@ func (s *subsonic) initRouter() {
 	setUpHandler("/getArtist", s.getArtist)
 	setUpHandler("/getArtistInfo", s.getArtistInfo)
 	setUpHandler("/getArtistInfo2", s.getArtistInfo2)
-	setUpHandler("/getCoverArt", s.getCoverArt)
+	setUpHandler("/getCoverArt", s.getCoverArt, "GET", "HEAD")
 	setUpHandler("/stream", s.stream, "GET", "HEAD")
 	setUpHandler("/download", s.stream, "GET", "HEAD")
 	setUpHandler("/getSong", s.getSong)