On 10/12/21 11:55, Paul Gofman wrote:
Signed-off-by: Paul Gofman pgofman@codeweavers.com
Using SO_REUSEADDR is currently problematic when more than one UDP socket is bound to different interfaces. While that succeeds, it is unspecified which socket will receive a packet coming to INADDR_ANY. The filter being installed for each socket with SO_ATTACH_FILTER can only reject the packet coming for another interface but that rejected packed doesn't arrive to another socket. SO_BINDTODEVICE seems to do exactly what we want without installing any socket filters and without requiring SO_REUSEADDR or SO_REUSEPORT. It originally considered for implementing broadcast listen on interface bound sockets but it wasn't much useful by that time as the SO_BINDTODEVICE required CAP_NET_RAW privilege which is normally not available for a non-root user. However, that changed since Linux 5.7 [2]. This patch uses SO_BINDTODEVICE but falls back to the previous way if that fails. 1. https://www.winehq.org/pipermail/wine-devel/2011-October/092681.html 2. https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/patch/?id=c427bfec18f2190b8f4718785ee8ed2db4f84ee6server/sock.c | 28 ++++++++++++++++++++++------ 1 file changed, 22 insertions(+), 6 deletions(-)
diff --git a/server/sock.c b/server/sock.c index 03716cba90f..af08cd6be24 100644 --- a/server/sock.c +++ b/server/sock.c @@ -1756,12 +1756,14 @@ static int accept_into_socket( struct sock *sock, struct sock *acceptsock )
#ifdef IP_BOUND_IF
-static int bind_to_index( int fd, in_addr_t bind_addr, unsigned int index ) +static int bind_to_index( int fd, in_addr_t bind_addr, const char *name, unsigned int index, BOOL *need_reuse_addr )
Perhaps we should rename bind_to_index to bind_to_iface or something, then?
Actually, for that matter, should we just pass the name, and call if_nametoindex() only as needed?
Also, do we really need to return a bool? Can we just call SO_REUSEADDR in bind_to_index() instead? That strikes me as cleaner, despite duplicating the call.