pkg/email: handle emails without Content-Type header

git-send-email sends emails without Content-Type,
let's assume it's text.

2 files changed, 8 insertions, 4 deletions

diff --git a/pkg/email/parser.go b/pkg/email/parser.go
index 37490af1d..702c17a0c 100644
--- a/pkg/email/parser.go
+++ b/pkg/email/parser.go
@@ -246,9 +246,14 @@ func extractArgsLine(body []byte) string {
 }
 
 func parseBody(r io.Reader, headers mail.Header) (body []byte, attachments [][]byte, err error) {
-	mediaType, params, err := mime.ParseMediaType(headers.Get("Content-Type"))
-	if err != nil {
-		return nil, nil, fmt.Errorf("failed to parse email header 'Content-Type': %v", err)
+	// git-send-email sends emails without Content-Type, let's assume it's text.
+	mediaType := "text/plain"
+	var params map[string]string
+	if contentType := headers.Get("Content-Type"); contentType != "" {
+		mediaType, params, err = mime.ParseMediaType(headers.Get("Content-Type"))
+		if err != nil {
+			return nil, nil, fmt.Errorf("failed to parse email header 'Content-Type': %v", err)
+		}
 	}
 	// Note: mime package handles quoted-printable internally.
 	if strings.ToLower(headers.Get("Content-Transfer-Encoding")) == "base64" {
diff --git a/pkg/email/parser_test.go b/pkg/email/parser_test.go
index ed4a76f27..69e237806 100644
--- a/pkg/email/parser_test.go
+++ b/pkg/email/parser_test.go
@@ -320,7 +320,6 @@ Message-ID: <123>
 Subject: test subject
 From: Bob <bob@example.com>
 To: syzbot <bot@example.com>, Alice <alice@example.com>
-Content-Type: text/plain
 
 #syz  invalid   	 
 text body