fix: set correct Content-Type when downloading images

Fixes #414

Signed-off-by: Andrey Smirnov <andrey.smirnov@siderolabs.com>

Author: smira

internal/asset/cache/s3/s3.go

@@ -19,6 +19,7 @@ import (
 	"go.uber.org/zap"
 
 	"github.com/siderolabs/image-factory/internal/asset/cache"
+	"github.com/siderolabs/image-factory/internal/mime"
 )
 
 const (
@@ -173,6 +174,7 @@ func (c *Cache) Put(ctx context.Context, profileID string, asset cache.BootAsset
 	}
 
 	stat, err := c.s3cli.PutObject(ctx, c.bucketName, key, data, asset.Size(), minio.PutObjectOptions{
+		ContentType:        mime.ContentType(filename),
 		ContentDisposition: fmt.Sprintf(`attachment; filename="%s"`, filename),
 	})
 	if err != nil {
@@ -212,6 +214,7 @@ func (c *Cache) Put(ctx context.Context, profileID string, asset cache.BootAsset
 func hasRequiredMetadata(metadata http.Header) bool {
 	for _, key := range []string{
 		"Content-Disposition",
+		"Content-Type",
 	} {
 		if metadata.Get(key) == "" {
 			return false

internal/frontend/http/image.go

@@ -8,9 +8,7 @@ import (
 	"context"
 	"fmt"
 	"io"
-	"mime"
 	"net/http"
-	"path/filepath"
 	"strconv"
 	"strings"
 
@@ -19,6 +17,7 @@ import (
 	"go.uber.org/zap"
 
 	"github.com/siderolabs/image-factory/internal/asset/cache"
+	"github.com/siderolabs/image-factory/internal/mime"
 	"github.com/siderolabs/image-factory/internal/profile"
 )
 
@@ -83,11 +82,7 @@ func (f *Frontend) handleImage(ctx context.Context, w http.ResponseWriter, r *ht
 	}
 
 	w.Header().Set("Content-Length", strconv.FormatInt(asset.Size(), 10))
-
-	if ext := filepath.Ext(path); ext != "" {
-		w.Header().Set("Content-Type", mime.TypeByExtension(ext))
-	}
-
+	w.Header().Set("Content-Type", mime.ContentType(path))
 	w.Header().Set("Content-Disposition", fmt.Sprintf(`attachment; filename="%s"`, filename))
 	w.WriteHeader(http.StatusOK)
 

internal/integration/download_test.go

@@ -24,6 +24,7 @@ import (
 	"github.com/siderolabs/gen/xtesting/must"
 	"github.com/siderolabs/go-blockdevice/v2/blkid"
 	"github.com/siderolabs/go-pointer"
+	"github.com/siderolabs/image-factory/internal/mime"
 	"github.com/siderolabs/talos/pkg/machinery/imager/quirks"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -157,6 +158,7 @@ func downloadAssetAndMatchSize(ctx context.Context, t *testing.T, baseURL string
 
 	require.Equal(t, http.StatusOK, resp.StatusCode)
 	require.Contains(t, resp.Header, "Content-Disposition")
+	assert.Equal(t, mime.ContentType(path), resp.Header.Get("Content-Type"))
 
 	size := matchSizeAndType(t, body, fileType, expectedSize)
 

internal/mime/mime.go

@@ -0,0 +1,45 @@
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+// Package mime provides MIME type detection based on file extensions.
+package mime
+
+import (
+	"mime"
+	"path/filepath"
+)
+
+// ContentType returns the MIME type for a given filename based on its extension.
+//
+// If the extension is unknown, it returns "application/octet-stream".
+func ContentType(filename string) string {
+	ext := filepath.Ext(filename)
+
+	var mimeType string
+
+	switch ext {
+	case ".efi":
+		// see https://www.iana.org/assignments/media-types/media-types.xhtml
+		mimeType = "application/efi"
+	case ".iso":
+		mimeType = "application/x-iso9660-image"
+	case ".xz":
+		mimeType = "application/x-xz"
+	case ".gz":
+		mimeType = "application/gzip"
+	case ".qcow2":
+		mimeType = "application/x-qemu-disk"
+	default:
+		// no match
+		if ext != "" {
+			mimeType = mime.TypeByExtension(ext)
+		}
+
+		if mimeType == "" {
+			mimeType = "application/octet-stream"
+		}
+	}
+
+	return mimeType
+}

internal/mime/mime_test.go

@@ -0,0 +1,36 @@
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+package mime_test
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"github.com/siderolabs/image-factory/internal/mime"
+)
+
+func TestContentType(t *testing.T) {
+	t.Parallel()
+
+	for _, test := range []struct {
+		filename string
+		expected string
+	}{
+		{"file.efi", "application/efi"},
+		{"file.unknown", "application/octet-stream"},
+		{"file.txt", "text/plain; charset=utf-8"},
+		{"file.iso", "application/x-iso9660-image"},
+		{"file.tar.gz", "application/gzip"},
+		{"file.qcow2", "application/x-qemu-disk"},
+		{"file.xz", "application/x-xz"},
+	} {
+		t.Run(test.filename, func(t *testing.T) {
+			t.Parallel()
+
+			assert.Equal(t, test.expected, mime.ContentType(test.filename))
+		})
+	}
+}