From 606600a176c981addcfedb0698f13fd0f2f4446e Mon Sep 17 00:00:00 2001 From: Sebastian Ottlik Date: Wed, 2 Oct 2013 12:23:12 +0200 Subject: util: add socket_set_fast_reuse function which will replace setting SO_REUSEADDR If a socket is closed it remains in TIME_WAIT state for some time. On operating systems using BSD sockets the endpoint of the socket may not be reused while in this state unless SO_REUSEADDR was set on the socket. On windows on the other hand the default behaviour is to allow reuse (i.e. identical to SO_REUSEADDR on other operating systems) and setting SO_REUSEADDR on a socket allows it to be bound to a endpoint even if the endpoint is already used by another socket independently of the other sockets state. This can even result in undefined behaviour. Many sockets used by QEMU should not block the use of their endpoint after being closed while they are still in TIME_WAIT state. Currently QEMU sets SO_REUSEADDR for such sockets, which can lead to problems on Windows. This patch introduces the function socket_set_fast_reuse that should be used instead of setting SO_REUSEADDR when fast socket reuse is desired and behaves correctly on all operating systems. As a failure of this function can only be caused by bad QEMU internal errors, an assertion handles these situations. The return value is still passed on, to minimize changes in client code and prevent unused variable warnings if NDEBUG is defined. Signed-off-by: Sebastian Ottlik Reviewed-by: Eric Blake Signed-off-by: Stefan Weil --- include/qemu/sockets.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/qemu/sockets.h') diff --git a/include/qemu/sockets.h b/include/qemu/sockets.h index c5174d7..45588d7 100644 --- a/include/qemu/sockets.h +++ b/include/qemu/sockets.h @@ -39,6 +39,7 @@ int socket_set_cork(int fd, int v); int socket_set_nodelay(int fd); void qemu_set_block(int fd); void qemu_set_nonblock(int fd); +int socket_set_fast_reuse(int fd); int send_all(int fd, const void *buf, int len1); int recv_all(int fd, void *buf, int len1, bool single_read); -- cgit v1.1