[Qemu-devel] [PATCH RFC 4/4] util: do not set SO_REUSEADDR on Windows

[Sebastian Ottlik <ottlik@fzi.de>]

If a socket is closed it may remain in TIME_WAIT state for some time. On most
operating systems the local port of the connection or socket may not be reeused
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 may result in
undefined behaviour. Fix this issue by no setting SO_REUSEADDR on windows.

Signed-off-by: Sebastian Ottlik <ottlik@fzi.de>
---
 util/qemu-sockets.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/util/qemu-sockets.c b/util/qemu-sockets.c
index 095716e..b5ea66a 100644
--- a/util/qemu-sockets.c
+++ b/util/qemu-sockets.c
@@ -154,8 +154,9 @@ int inet_listen_opts(QemuOpts *opts, int port_offset, Error **errp)
             }
             continue;
         }
-
+#ifndef _WIN32
         qemu_setsockopt(slisten, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));
+#endif
 #ifdef IPV6_V6ONLY
         if (e->ai_family == PF_INET6) {
             /* listen on both ipv4 and ipv6 */
@@ -274,7 +275,9 @@ static int inet_connect_addr(struct addrinfo *addr, bool *in_progress,
         error_set_errno(errp, errno, QERR_SOCKET_CREATE_FAILED);
         return -1;
     }
+#ifndef _WIN32
     qemu_setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));
+#endif
     if (connect_state != NULL) {
         qemu_set_nonblock(sock);
     }
@@ -455,7 +458,9 @@ int inet_dgram_opts(QemuOpts *opts, Error **errp)
         error_set_errno(errp, errno, QERR_SOCKET_CREATE_FAILED);
         goto err;
     }
+#ifndef _WIN32
     qemu_setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));
+#endif
 
     /* bind socket */
     if (bind(sock, local->ai_addr, local->ai_addrlen) < 0) {
-- 
1.7.9.5