Fix dco_win and multisocket interaction

The recent introduction of the multisocket support
did not account for some Windows-specific DCO paths.
This patch restores correct behavior on Windows.

Key changes:

 - Add WIN32 guards around DCO-specifc code.
 - Disable wait_signal() when running in
   server mode, as it conflicts with the
   event engine since Windows handles
   signals as I/Os.
 - Ensure correct socket handling for TCP
   vs UDP.

Github: closes OpenVPN/openvpn#720

Change-Id: I719b1aa2d2f4d63dc9c18d8e313fba339e3e4b0c
Signed-off-by: Gianmarco De Gregori <[email protected]>
Acked-by: Lev Stipakov <[email protected]>
Message-Id: <[email protected]>
URL: https://www.mail-archive.com/[email protected]/msg31419.html
Signed-off-by: Gert Doering <[email protected]>

Author: itsGiaan

src/openvpn/forward.c

@@ -2072,7 +2072,7 @@ multi_io_process_flags(struct context *c, struct event_set *es,
     /*
      * Calculate the flags based on the provided 'flags' argument.
      */
-    if (flags & IOW_WAIT_SIGNAL)
+    if ((c->options.mode != MODE_SERVER) && (flags & IOW_WAIT_SIGNAL))
     {
         wait_signal(es, (void *)err_shift);
     }

src/openvpn/mtcp.c

@@ -181,7 +181,8 @@ multi_tcp_process_outgoing_link(struct multi_context *m, bool defer, const unsig
 
     if (mi)
     {
-        if (defer || mbuf_defined(mi->tcp_link_out_deferred))
+        if ((defer && !proto_is_dgram(mi->context.c2.link_sockets[0]->info.proto))
+            || mbuf_defined(mi->tcp_link_out_deferred))
         {
             /* save to queue */
             struct buffer *buf = &mi->context.c2.to_link;

src/openvpn/multi_io.c

@@ -176,10 +176,13 @@ multi_io_wait(struct multi_context *m)
     int status, i;
     unsigned int *persistent = &m->multi_io->tun_rwflags;
 
-    for (i = 0; i < m->top.c1.link_sockets_num; i++)
+    if (!tuntap_is_dco_win(m->top.c1.tuntap))
     {
-        socket_set_listen_persistent(m->top.c2.link_sockets[i], m->multi_io->es,
-                                     &m->top.c2.link_sockets[i]->ev_arg);
+        for (i = 0; i < m->top.c1.link_sockets_num; i++)
+        {
+            socket_set_listen_persistent(m->top.c2.link_sockets[i], m->multi_io->es,
+                                         &m->top.c2.link_sockets[i]->ev_arg);
+        }
     }
 
     if (has_udp_in_local_list(&m->top.options))
@@ -202,7 +205,8 @@ multi_io_wait(struct multi_context *m)
     }
 #endif
     tun_set(m->top.c1.tuntap, m->multi_io->es, EVENT_READ, MULTI_IO_TUN, persistent);
-#if defined(TARGET_LINUX) || defined(TARGET_FREEBSD)
+#if defined(ENABLE_DCO) \
+    && (defined(TARGET_LINUX) || defined(TARGET_FREEBSD) || defined(TARGET_WIN32))
     dco_event_set(&m->top.c1.tuntap->dco, m->multi_io->es, MULTI_IO_DCO);
 #endif
 
@@ -535,7 +539,8 @@ multi_io_process_io(struct multi_context *m)
                     multi_io_action(m, mi, TA_INITIAL, false);
                 }
             }
-#if defined(ENABLE_DCO) && (defined(TARGET_LINUX) || defined(TARGET_FREEBSD))
+#if defined(ENABLE_DCO) \
+            && (defined(TARGET_LINUX) || defined(TARGET_FREEBSD) || defined(TARGET_WIN32))
             /* incoming data on DCO? */
             else if (e->arg == MULTI_IO_DCO)
             {