#64: Set filename for included images

3 files changed, 22 insertions, 5 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3adbf45..aa5a807 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+### Added
+- [Issue #64](https://github.com/Necoro/feed2imap-go/issues/64): Set filename for included images.
 
 ## [1.2.0] - 2021-10-20
 ### Added
diff --git a/internal/feed/item.go b/internal/feed/item.go
index f7dd506..b45f5c5 100644
--- a/internal/feed/item.go
+++ b/internal/feed/item.go
@@ -17,6 +17,7 @@ import (
 type feedImage struct {
 	image []byte
 	mime  string
+	name  string
 }
 
 type Item struct {
@@ -69,8 +70,8 @@ func (item *Item) AddReason(reason string) {
 	}
 }
 
-func (item *Item) addImage(img []byte, mime string) int {
-	i := feedImage{img, mime}
+func (item *Item) addImage(img []byte, mime string, name string) int {
+	i := feedImage{img, mime, name}
 	item.images = append(item.images, i)
 	return len(item.images)
 }
diff --git a/internal/feed/mail.go b/internal/feed/mail.go
index b6cd231..f5863a6 100644
--- a/internal/feed/mail.go
+++ b/internal/feed/mail.go
@@ -123,10 +123,19 @@ func (item *Item) writeHtmlPart(w *message.Writer) error {
 	return item.writeContentPart(w, "html", template.Html)
 }
 
+func (img *feedImage) buildNameMap(key string) map[string]string {
+	if img.name == "" {
+		return nil
+	}
+	return map[string]string{key: img.name}
+}
+
 func (img *feedImage) writeImagePart(w *message.Writer, cid string) error {
 	var ih message.Header
-	ih.SetContentType(img.mime, nil)
-	ih.SetContentDisposition("inline", nil)
+	// set filename for both Type and Disposition
+	// according to standard, it belongs to the latter -- but some clients expect the former
+	ih.SetContentType(img.mime, img.buildNameMap("name"))
+	ih.SetContentDisposition("inline", img.buildNameMap("filename"))
 	ih.Set("Content-Transfer-Encoding", "base64")
 	ih.SetText("Content-ID", fmt.Sprintf("<%s>", cid))
 
@@ -288,7 +297,12 @@ func (item *Item) downloadImage(src string) string {
 	if feed.EmbedImages {
 		return "data:" + mime + ";base64," + base64.StdEncoding.EncodeToString(img)
 	} else {
-		idx := item.addImage(img, mime)
+		name := path.Base(src)
+		if name == "/" || name == "." || name == " " {
+			name = ""
+		}
+
+		idx := item.addImage(img, mime, name)
 		return "cid:" + cidNr(idx)
 	}
 }