On 09/10/2013 07:26 AM, Sebastian Ottlik wrote:
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 and does the right thing on all operating systems.
Signed-off-by: Sebastian Ottlik <address@hidden>
---
+int socket_set_fast_reuse(int fd)
+{
+ int val = 1, ret;
+
+ ret = setsockopt(fd, SOL_SOCKET, SO_REUSEADDR,
+ (const char *)&val, sizeof(val));
+
+ if (ret < 0) {
+ perror("setsockopt(SOL_SOCKET, SO_REUSEADDR)");
+ }
This would be the first use of perror in this file; I'm not sure if that
is the right function, or if there is a better thing to be using (in
fact, returning -1 and letting the client decide whether to issue a
warning may even be better).