lib-smtp: client: Prevent sending an empty XCLIENT command when the first parameter...

diff --git a/src/lib-smtp/smtp-client-connection.c b/src/lib-smtp/smtp-client-connection.c
index c1e548890cacf80dec656e3bb9b6bb760281de60..3c6d3f1c2714f08a20b0530bfb0e993cf4f4cf82 100644 (file)
--- a/src/lib-smtp/smtp-client-connection.c
+++ b/src/lib-smtp/smtp-client-connection.c
@@ -683,12 +683,15 @@ smtp_client_connection_xclient_add(struct smtp_client_connection *conn,
        size_t prev_offset = str_len(str);
        const char *new_field;
 
+       i_assert(prev_offset >= offset);
+
        str_append_c(str, ' ');
        str_append(str, field);
        str_append_c(str, '=');
        smtp_xtext_encode_cstr(str, value);
 
-       if (str_len(str) <= SMTP_CLIENT_BASE_LINE_LENGTH_LIMIT)
+       if (prev_offset == offset ||
+           str_len(str) <= SMTP_CLIENT_BASE_LINE_LENGTH_LIMIT)
                return;
                
        /* preserve field we just added */