set utf-8 encoded filenames

Characters in HTTP headers should be encoded with the ISO 8859-1
character set. So the previous implementation was wrong.
Browsers may have slightly different behaviours but this seems to work
in firefox.

server/files.go

@@ -8,6 +8,7 @@ import (
 	"fmt"
 	"io"
 	"mime/multipart"
+	"net/url"
 	"strconv"
 	"strings"
 
@@ -128,17 +129,17 @@ func Download(ctx context.Context, input *DownloadInput) (*huma.StreamResponse,
 			writer := ctx.BodyWriter()
 
 			stat, err := obj.Stat()
-			filename := stat.UserMetadata["Filename"]
+			filename := url.PathEscape(stat.UserMetadata["Filename"])
 			content_type := stat.UserMetadata["Type"]
 
 			main_type, _, _ := strings.Cut(content_type, "/")
 
 			ctx.SetHeader("Accept-Range", "bytes")
 			ctx.SetHeader("Content-Length", fmt.Sprintf("%d", stat.Size))
 			if main_type == "text" {
-				ctx.SetHeader("Content-Disposition", fmt.Sprintf("inline; filename=%s", filename))
+				ctx.SetHeader("Content-Disposition", fmt.Sprintf("inline; filename=\"%s\"; filename*=UTF-8''%s", filename, filename))
 			} else {
-				ctx.SetHeader("Content-Disposition", fmt.Sprintf("attachment; filename=%s", filename))
+				ctx.SetHeader("Content-Disposition", fmt.Sprintf("attachment; filename=\"%s\"; filename*=UTF-8''%s", filename, filename))
 			}
 			ctx.SetHeader("Content-Type", content_type)
 

server/producer_test.go

@@ -8,6 +8,7 @@ import (
 	"fmt"
 	"mime/multipart"
 	"net/http/httptest"
+	"net/url"
 	"regexp"
 	"testing"
 
@@ -63,7 +64,7 @@ func TestUploadDownload(t *testing.T) {
 
 	test_data := []byte("hello world")
 	mime := mimetype.Detect(test_data)
-	filename := "test_file"
+	filename := "test file"
 	upload_data := uploadData(t, api, test_data, filename)
 
 	path := fmt.Sprintf("/%s", upload_data.Body.ID)
@@ -96,7 +97,7 @@ func TestUploadDownload(t *testing.T) {
 	}
 
 	matched, _ := regexp.MatchString(
-		fmt.Sprintf("filename=%s", regexp.QuoteMeta(filename)),
+		fmt.Sprintf("filename=\"%s\"", regexp.QuoteMeta(url.PathEscape(filename))),
 		content_disposition_header,
 	)