net: call socket_set_fast_reuse instead of setting SO_REUSEADDR

SO_REUSEADDR should be avoided on Windows but is desired on other operating
systems. So instead of setting it we call socket_set_fast_reuse that will result
in the appropriate behaviour on all operating systems.

An exception to this rule are multicast sockets where it is sensible to have
multiple sockets listen on the same ip and port and we should set SO_REUSEADDR
on windows.

Signed-off-by: Sebastian Ottlik <ottlik@fzi.de>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Stefan Weil <sw@weilnetz.de>

1 files changed, 10 insertions, 9 deletions

diff --git a/net/socket.c b/net/socket.c
index e61309d..fb21e20 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -262,6 +262,11 @@ static int net_socket_mcast_create(struct sockaddr_in *mcastaddr, struct in_addr
         return -1;
     }
 
+    /* Allow multiple sockets to bind the same multicast ip and port by setting
+     * SO_REUSEADDR. This is the only situation where SO_REUSEADDR should be set
+     * on windows. Use socket_set_fast_reuse otherwise as it sets SO_REUSEADDR
+     * only on posix systems.
+     */
     val = 1;
     ret = qemu_setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &val, sizeof(val));
     if (ret < 0) {
@@ -510,7 +515,7 @@ static int net_socket_listen_init(NetClientState *peer,
     NetClientState *nc;
     NetSocketState *s;
     struct sockaddr_in saddr;
-    int fd, val, ret;
+    int fd, ret;
 
     if (parse_host_port(&saddr, host_str) < 0)
         return -1;
@@ -522,9 +527,7 @@ static int net_socket_listen_init(NetClientState *peer,
     }
     qemu_set_nonblock(fd);
 
-    /* allow fast reuse */
-    val = 1;
-    qemu_setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &val, sizeof(val));
+    socket_set_fast_reuse(fd);
 
     ret = bind(fd, (struct sockaddr *)&saddr, sizeof(saddr));
     if (ret < 0) {
@@ -645,7 +648,7 @@ static int net_socket_udp_init(NetClientState *peer,
                                  const char *lhost)
 {
     NetSocketState *s;
-    int fd, val, ret;
+    int fd, ret;
     struct sockaddr_in laddr, raddr;
 
     if (parse_host_port(&laddr, lhost) < 0) {
@@ -661,11 +664,9 @@ static int net_socket_udp_init(NetClientState *peer,
         perror("socket(PF_INET, SOCK_DGRAM)");
         return -1;
     }
-    val = 1;
-    ret = qemu_setsockopt(fd, SOL_SOCKET, SO_REUSEADDR,
-                          &val, sizeof(val));
+
+    ret = socket_set_fast_reuse(fd);
     if (ret < 0) {
-        perror("setsockopt(SOL_SOCKET, SO_REUSEADDR)");
         closesocket(fd);
         return -1;
     }