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[Openvpn-devel,M] Change in openvpn[master]: event/multi: add event_arg object to make event handling more generic

Message ID bc2908feebcce0b7ae7dfaf3b978f9d2a450cde1-HTML@gerrit.openvpn.net
State Not Applicable
Headers show
Series [Openvpn-devel,M] Change in openvpn[master]: event/multi: add event_arg object to make event handling more generic | expand

Commit Message

flichtenheld (Code Review) Nov. 15, 2023, 1:45 p.m. UTC 
Attention is currently required from: flichtenheld, plaisthos.

Hello plaisthos, flichtenheld,

I'd like you to do a code review.
Please visit

    http://gerrit.openvpn.net/c/openvpn/+/430?usp=email

to review the following change.


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

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 pocked 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 i/o.

Change-Id: If11e901c26fc5aafdcfd59a214d70c6e6a548f40
Signed-off-by: Antonio Quartulli <a@unstable.cc>
---
M src/openvpn/event.h
M src/openvpn/mtcp.c
M src/openvpn/multi.c
M src/openvpn/multi.h
M src/openvpn/socket.c
M src/openvpn/socket.h
6 files changed, 58 insertions(+), 13 deletions(-)



  git pull ssh://gerrit.openvpn.net:29418/openvpn refs/changes/30/430/1
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Patch

diff --git a/src/openvpn/event.h b/src/openvpn/event.h
index 6282873..23a6799 100644
--- a/src/openvpn/event.h
+++ b/src/openvpn/event.h
@@ -126,6 +126,20 @@ 
     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 62eb14b..9d383af 100644
--- a/src/openvpn/mtcp.c
+++ b/src/openvpn/mtcp.c
@@ -253,7 +253,7 @@ 
         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);
     }
 }
@@ -264,7 +264,8 @@ 
 {
     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))
@@ -692,21 +693,43 @@ 
     for (i = 0; i < mtcp->n_esr; ++i)
     {
         struct event_set_return *e = &mtcp->esr[i];
+        struct event_arg *ev_arg = (struct event_arg *)e->arg;
 
-        /* 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)
+            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
diff --git a/src/openvpn/multi.c b/src/openvpn/multi.c
index 8b490ed..af04dc8 100644
--- a/src/openvpn/multi.c
+++ b/src/openvpn/multi.c
@@ -823,6 +823,9 @@ 
         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 6b1c68d..7656bac 100644
--- a/src/openvpn/multi.h
+++ b/src/openvpn/multi.h
@@ -102,6 +102,7 @@ 
     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;
     struct gc_arena gc;
     bool halt;
     int refcount;
diff --git a/src/openvpn/socket.c b/src/openvpn/socket.c
index 903f98b..8ee14df 100644
--- a/src/openvpn/socket.c
+++ b/src/openvpn/socket.c
@@ -1827,6 +1827,8 @@ 
     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 bfc1253..39e30b8 100644
--- a/src/openvpn/socket.h
+++ b/src/openvpn/socket.h
@@ -166,6 +166,8 @@ 
 {
     struct link_socket_info info;
 
+    struct event_arg ev_arg;
+
     socket_descriptor_t sd;
     socket_descriptor_t ctrl_sd; /* only used for UDP over Socks */