forward,recall: fix charsets in part attachment

Fix charset to UTF-8 in part attachments. The forward and recall
commands fetch message parts with the go-message package which decodes
to UTF-8. Hence, we should set the charset of the part attachment to
utf-8 and not just copying over the one from the original message.

Reported-by: Bence Ferdinandy <bence@ferdinandy.com>
Signed-off-by: Koni Marti <koni.marti@gmail.com>
Acked-by: Robin Jarry <robin@jarry.cc>

commands/msg/forward.go

@@ -198,12 +198,13 @@ func (forward) Execute(aerc *widgets.Aerc, args []string) error {
 					}
 					store.FetchBodyPart(msg.Uid, p, func(reader io.Reader) {
 						mime := fmt.Sprintf("%s/%s", bs.MIMEType, bs.MIMESubType)
-						name, ok := bs.Params["name"]
+						params := lib.SetUtf8Charset(bs.Params)
+						name, ok := params["name"]
 						if !ok {
 							name = fmt.Sprintf("%s_%s_%d", bs.MIMEType, bs.MIMESubType, rand.Uint64())
 						}
 						mu.Lock()
-						composer.AddPartAttachment(name, mime, bs.Params, reader)
+						composer.AddPartAttachment(name, mime, params, reader)
 						mu.Unlock()
 					})
 				}

commands/msg/recall.go

@@ -204,12 +204,13 @@ func (Recall) Execute(aerc *widgets.Aerc, args []string) error {
 					}
 					msg.FetchBodyPart(p, func(reader io.Reader) {
 						mime := fmt.Sprintf("%s/%s", bs.MIMEType, bs.MIMESubType)
-						name, ok := bs.Params["name"]
+						params := lib.SetUtf8Charset(bs.Params)
+						name, ok := params["name"]
 						if !ok {
 							name = fmt.Sprintf("%s_%s_%d", bs.MIMEType, bs.MIMESubType, rand.Uint64())
 						}
 						mu.Lock()
-						composer.AddPartAttachment(name, mime, bs.Params, reader)
+						composer.AddPartAttachment(name, mime, params, reader)
 						mu.Unlock()
 					})
 				}

lib/attachment.go

@@ -7,7 +7,9 @@ import (
 	"net/http"
 	"os"
 	"path/filepath"
+	"strings"
 
+	"git.sr.ht/~rjarry/aerc/logging"
 	"github.com/emersion/go-message/mail"
 	"github.com/pkg/errors"
 )
@@ -134,3 +136,18 @@ func (pa *PartAttachment) WriteTo(w *mail.Writer) error {
 	}
 	return nil
 }
+
+// SetUtf8Charset sets the charset in a params map to UTF-8.
+func SetUtf8Charset(origParams map[string]string) map[string]string {
+	params := make(map[string]string)
+	for k, v := range origParams {
+		switch strings.ToLower(k) {
+		case "charset":
+			logging.Infof("substitute charset %s with utf-8", v)
+			params[k] = "utf-8"
+		default:
+			params[k] = v
+		}
+	}
+	return params
+}