The server will only overwrite the mac if it is zero. Ths allows acting in place of (non-alfred) legacy clients by injecting their data with the correct source mac. Signed-off-by: Dominik Heidler <dominik(a)heidler.eu> --- unix_sock.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/unix_sock.c b/unix_sock.c index 3c7e583..d7578a3 100644 --- a/unix_sock.c +++ b/unix_sock.c @@ -119,7 +119,13 @@ static int unix_sock_add_data(struct globals *globals, data = push->data; data_len = ntohs(data->header.length); - memcpy(data->source, &interface->hwaddr, sizeof(interface->hwaddr)); + + /* clients should set the source mac to 00:00:00:00:00:00 + * to make the server set the source for them + */ + static const char zero[ETH_ALEN] = { 0 }; + if (!memcmp(zero, data->source, sizeof(data->source))) + memcpy(data->source, &interface->hwaddr, sizeof(interface->hwaddr)); if ((int)(data_len + sizeof(*data)) > len) goto err; -- 2.7.2