event/multi: add event_arg object to make event handling more generic

In order to prepare the event handling code to deal with multiple
listening sockets, we have to make sure that it is possible to
distinguish which of these sockets have been poked by an incoming
connection request.

To achieve that, this patch changes the object being passed as
event handler argument, from a "partly integer-evaluated variable"
to a full struct with a proper type attribute.

This struct will allow the code to carry around the particular
listening socket where the connection is being established.

This change affects the TCP server code path only as UDP servers
use only one socket to handle all clients.

Change-Id: Icd7f6a2ad350cdc2312b3e80fa0dbdd7e4311d2e
Signed-off-by: Antonio Quartulli <a@unstable.cc>
Signed-off-by: Gianmarco De Gregori <gianmarco@mandelbit.com>
Acked-by: Frank Lichtenheld <frank@lichtenheld.com>
Message-Id: <20241023080853.3710-1-gert@greenie.muc.de>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg29602.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>

diff --git a/src/openvpn/event.h b/src/openvpn/event.h
index 856551adf57557cef49f00b039c2935b3d5fecaf..844ea7b330f2884b08aea99a94a4a69e48f5147b 100644 (file)
--- a/src/openvpn/event.h
+++ b/src/openvpn/event.h
@@ -126,6 +126,20 @@ struct event_set
     struct event_set_functions func;
 };
 
+typedef enum {
+    EVENT_ARG_MULTI_INSTANCE = 0,
+    EVENT_ARG_LINK_SOCKET,
+} event_arg_t;
+
+/* generic event argument object to pass to event_ctl() */
+struct event_arg
+{
+    event_arg_t type;
+    union {
+        struct multi_instance *mi; /* if type = EVENT_ARG_MULTI_INSTANCE */
+    } u;
+};
+
 /*
  * maxevents on input:  desired max number of event_t descriptors
  *                      simultaneously set with event_ctl

diff --git a/src/openvpn/mtcp.c b/src/openvpn/mtcp.c
index 3ae8be7361ffa902923f67e4834839a15dbcdabf..67e3e8e263d58ca6462f9b21ccf20fc3ea106494 100644 (file)
--- a/src/openvpn/mtcp.c
+++ b/src/openvpn/mtcp.c
@@ -54,7 +54,6 @@
 /*
  * Special tags passed to event.[ch] functions
  */
-#define MTCP_SOCKET      ((void *)1)
 #define MTCP_TUN         ((void *)2)
 #define MTCP_SIG         ((void *)3) /* Only on Windows */
 #define MTCP_MANAGEMENT ((void *)4)
@@ -245,7 +244,7 @@ multi_tcp_set_global_rw_flags(struct multi_context *m, struct multi_instance *mi
         socket_set(mi->context.c2.link_socket,
                    m->mtcp->es,
                    mbuf_defined(mi->tcp_link_out_deferred) ? EVENT_WRITE : EVENT_READ,
-                   mi,
+                   &mi->ev_arg,
                    &mi->tcp_rwflags);
     }
 }
@@ -255,8 +254,8 @@ multi_tcp_wait(const struct context *c,
                struct multi_tcp *mtcp)
 {
     int status;
-    unsigned int *persistent = &mtcp->tun_rwflags;
-    socket_set_listen_persistent(c->c2.link_socket, mtcp->es, MTCP_SOCKET);
+    socket_set_listen_persistent(c->c2.link_socket, mtcp->es,
+                                 &c->c2.link_socket->ev_arg);
 
 #ifdef _WIN32
     if (tuntap_is_wintun(c->c1.tuntap))
@@ -272,7 +271,7 @@ multi_tcp_wait(const struct context *c,
         persistent = NULL;
     }
 #endif
-    tun_set(c->c1.tuntap, mtcp->es, EVENT_READ, MTCP_TUN, persistent);
+    tun_set(c->c1.tuntap, mtcp->es, EVENT_READ, MTCP_TUN, &mtcp->tun_rwflags);
 #if defined(TARGET_LINUX) || defined(TARGET_FREEBSD)
     dco_event_set(&c->c1.tuntap->dco, mtcp->es, MTCP_DCO);
 #endif
@@ -685,20 +684,43 @@ multi_tcp_process_io(struct multi_context *m)
     {
         struct event_set_return *e = &mtcp->esr[i];
 
-        /* incoming data for instance? */
+        /* incoming data for instance or listening socket? */
         if (e->arg >= MTCP_N)
         {
-            struct multi_instance *mi = (struct multi_instance *) e->arg;
-            if (mi)
+            struct event_arg *ev_arg = (struct event_arg *)e->arg;
+            switch (ev_arg->type)
             {
-                if (e->rwflags & EVENT_WRITE)
-                {
-                    multi_tcp_action(m, mi, TA_SOCKET_WRITE_READY, false);
-                }
-                else if (e->rwflags & EVENT_READ)
-                {
-                    multi_tcp_action(m, mi, TA_SOCKET_READ, false);
-                }
+                struct multi_instance *mi;
+
+                /* react to event on child instance */
+                case EVENT_ARG_MULTI_INSTANCE:
+                    if (!ev_arg->u.mi)
+                    {
+                        msg(D_MULTI_ERRORS, "MULTI: mtcp_proc_io: null minstance");
+                        break;
+                    }
+
+                    mi = ev_arg->u.mi;
+                    if (e->rwflags & EVENT_WRITE)
+                    {
+                        multi_tcp_action(m, mi, TA_SOCKET_WRITE_READY, false);
+                    }
+                    else if (e->rwflags & EVENT_READ)
+                    {
+                        multi_tcp_action(m, mi, TA_SOCKET_READ, false);
+                    }
+                    break;
+
+                /* new incoming TCP client attempting to connect? */
+                case EVENT_ARG_LINK_SOCKET:
+                    ASSERT(m->top.c2.link_socket);
+                    socket_reset_listen_persistent(m->top.c2.link_socket);
+                    mi = multi_create_instance_tcp(m);
+                    if (mi)
+                    {
+                        multi_tcp_action(m, mi, TA_INITIAL, false);
+                    }
+                    break;
             }
         }
         else
@@ -723,18 +745,6 @@ multi_tcp_process_io(struct multi_context *m)
                     multi_tcp_action(m, NULL, TA_TUN_READ, false);
                 }
             }
-            /* new incoming TCP client attempting to connect? */
-            else if (e->arg == MTCP_SOCKET)
-            {
-                struct multi_instance *mi;
-                ASSERT(m->top.c2.link_socket);
-                socket_reset_listen_persistent(m->top.c2.link_socket);
-                mi = multi_create_instance_tcp(m);
-                if (mi)
-                {
-                    multi_tcp_action(m, mi, TA_INITIAL, false);
-                }
-            }
 #if defined(ENABLE_DCO) && (defined(TARGET_LINUX) || defined(TARGET_FREEBSD))
             /* incoming data on DCO? */
             else if (e->arg == MTCP_DCO)

diff --git a/src/openvpn/multi.c b/src/openvpn/multi.c
index 0509911d63d6ab4350a6103b359b68a1d1eadcf2..45b3cfa260d94ba75188c0162b333be2a014cea3 100644 (file)
--- a/src/openvpn/multi.c
+++ b/src/openvpn/multi.c
@@ -823,6 +823,9 @@ multi_create_instance(struct multi_context *m, const struct mroute_addr *real)
         goto err;
     }
 
+    mi->ev_arg.type = EVENT_ARG_MULTI_INSTANCE;
+    mi->ev_arg.u.mi = mi;
+
     perf_pop();
     gc_free(&gc);
     return mi;

diff --git a/src/openvpn/multi.h b/src/openvpn/multi.h
index 7167639e8697db5b13291c46cc7e8d0c46c03605..1b99ef70b8d3ac5183b6794f071fcd2aad82be20 100644 (file)
--- a/src/openvpn/multi.h
+++ b/src/openvpn/multi.h
@@ -102,6 +102,12 @@ struct multi_instance {
     struct schedule_entry se;  /* this must be the first element of the structure,
                                 * We cast between this and schedule_entry so the
                                 * beginning of the struct must be identical */
+
+    struct event_arg ev_arg;   /**< this struct will store a pointer to either mi or
+                                * link_socket, depending on the event type, to keep
+                                * it accessible it's placed within the same struct
+                                * it points to. */
+
     struct gc_arena gc;
     bool halt;
     int refcount;

diff --git a/src/openvpn/socket.c b/src/openvpn/socket.c
index 7b1e6038fafed2d5a068fd0edb09c63376549975..cf04090cdc6e9eaf21cdec564381faa207ae8dca 100644 (file)
--- a/src/openvpn/socket.c
+++ b/src/openvpn/socket.c
@@ -1830,6 +1830,8 @@ link_socket_new(void)
     ALLOC_OBJ_CLEAR(sock, struct link_socket);
     sock->sd = SOCKET_UNDEFINED;
     sock->ctrl_sd = SOCKET_UNDEFINED;
+    sock->ev_arg.type = EVENT_ARG_LINK_SOCKET;
+
     return sock;
 }
 

diff --git a/src/openvpn/socket.h b/src/openvpn/socket.h
index 04eb8a421d61be252a9e24c39f4942e25fc9f1d0..27caab4d42d141de3db308214fe8c5f7843462b9 100644 (file)
--- a/src/openvpn/socket.h
+++ b/src/openvpn/socket.h
@@ -178,6 +178,11 @@ struct link_socket
 {
     struct link_socket_info info;
 
+    struct event_arg ev_arg;   /**< this struct will store a pointer to either mi or
+                                * link_socket, depending on the event type, to keep
+                                * it accessible it's placed within the same struct
+                                * it points to. */
+
     socket_descriptor_t sd;
     socket_descriptor_t ctrl_sd; /* only used for UDP over Socks */