Re: wg(4): 'Address already in use' when wgrtable is changed

[YASUOKA Masahiko]

Hello,

Let me ask "ok",

The diff fixes the problem as follows:

Configure wg0 without wgrtable

# ifconfig wg0 create wgport 7111 wgkey `openssl rand -base64 32` up
# ifconfig wg0                                                       
wg0: flags=80c3<UP,BROADCAST,RUNNING,NOARP,MULTICAST> mtu 1420
        index 6 priority 0 llprio 3
        wgport 7111
        wgpubkey OVDrQ6wTjZckC12gcUk8aeoYvF5oZ0wuyH17eZcS2BA=
        groups: wg

afterwards, we start using a rtable which belongs rdomain 0,

# netstat -R
Rdomain 0
  Interfaces: lo0 vio0 vio1 enc0 pflog0 wg0
  Routing tables: 0 1

then we want to configure wgrtable to use that rtable,

# ifconfig wg0 wgrtable 1
ifconfig: SIOCSWG: Address already in use
# 

After the diff, the command is executed successfully.

  # ifconfig wg0 wgrtable 1
  #

ok?


When changing wgrtable to a rtable which belongs to the same rdomain
of the old one, close the existing socket first to prevent
EADDRINUSE.

Index: sys/net/if_wg.c
===================================================================
RCS file: /var/cvs/openbsd/src/sys/net/if_wg.c,v
retrieving revision 1.26
diff -u -p -r1.26 if_wg.c
--- sys/net/if_wg.c     21 Jul 2022 11:26:50 -0000      1.26
+++ sys/net/if_wg.c     22 Jul 2022 01:59:14 -0000
@@ -750,6 +750,16 @@ wg_bind(struct wg_softc *sc, in_port_t *
        int              retries = 0;
 retry:
 #endif
+
+       if (port == sc->sc_udp_port &&
+           rtable_l2(rtable) == rtable_l2(sc->sc_udp_rtable)) {
+               /* changing rtable in the same domain */
+               wg_socket_close(&sc->sc_so4);
+#ifdef INET6
+               wg_socket_close(&sc->sc_so6);
+#endif
+       }
+
        if ((ret = wg_socket_open(&so4, AF_INET, &port, &rtable, sc)) != 0)
                return ret;