This patch moves the state, that was previously tracked within the
multi_connection_established() function, into struct client_connect_state.  The
multi_connection_established() function can now be exited and re-entered as
many times as necessary - without losing the client-connect handling state.

The patch also adds the new return value CC_RET_DEFERRED which indicates that
the handler couldn't complete immediately, and needs to be called later.  At
that point multi_connection_established() will exit without indicating
completion.

Each client-connect handler now has an (optional) additional call-back:  The
call-back for handling the deferred case.  If the main call-back returns
CC_RET_DEFERRED, the next call to the handler will be through the deferred
call-back.

Signed-off-by: Fabian Knittel <fabian.knit...@lettink.de>

Patch V3: Use a static struct in multi_instance instead of using
          malloc/free and use two states (deffered with and without
          result) instead of one to eliminate the counter that was
          only tested for > 0.

Patch V5: Use new states in context_auth instead of the extra state
          that the patch series previously used.

Patch V6: Restructure code to make it a bit more readable, rebase on
          master.

Signed-off-by: Arne Schwabe <a...@rfc2549.org>
---
 src/openvpn/multi.c   | 168 +++++++++++++++++++++++++++++++-----------
 src/openvpn/multi.h   |  15 +++-
 src/openvpn/openvpn.h |   9 +++
 3 files changed, 147 insertions(+), 45 deletions(-)

diff --git a/src/openvpn/multi.c b/src/openvpn/multi.c
index 97b7df16..331891bc 100644
--- a/src/openvpn/multi.c
+++ b/src/openvpn/multi.c
@@ -2225,32 +2225,50 @@ multi_client_connect_source_ccd(struct multi_context *m,
     return ret;
 }
 
-static inline bool
-cc_check_return(int *cc_succeeded_count,
-                enum client_connect_return ret)
+typedef enum client_connect_return (*multi_client_connect_handler)
+    (struct multi_context *m, struct multi_instance *mi,
+    unsigned int *option_types_found);
+
+struct client_connect_handlers
+{
+    multi_client_connect_handler main;
+    multi_client_connect_handler deferred;
+};
+
+static enum client_connect_return
+multi_client_connect_fail(struct multi_context *m, struct multi_instance *mi,
+                          unsigned int *option_types_found)
 {
-    if (ret == CC_RET_SUCCEEDED)
+    /* Called null call-back.  This should never happen. */
+    return CC_RET_FAILED;
+}
+
+static const struct client_connect_handlers client_connect_handlers[] = {
     {
-        (*cc_succeeded_count)++;
-        return true;
-    }
-    else if (ret == CC_RET_FAILED)
+        .main = multi_client_connect_source_ccd,
+        .deferred = multi_client_connect_fail
+    },
     {
-        return false;
-    }
-    else if (ret == CC_RET_SKIPPED)
+        .main = multi_client_connect_call_plugin_v1,
+        .deferred = multi_client_connect_fail
+    },
     {
-        return true;
-    }
-    else
+        .main = multi_client_connect_call_plugin_v2,
+        .deferred = multi_client_connect_fail
+    },
+    {
+        .main = multi_client_connect_call_script,
+        .deferred = multi_client_connect_fail
+    },
     {
-        ASSERT(0);
+        .main = multi_client_connect_mda,
+        .deferred = multi_client_connect_fail
+    },
+    {
+        .main = NULL,
+        .deferred = NULL
     }
-}
-
-typedef enum client_connect_return (*multi_client_connect_handler)
-    (struct multi_context *m, struct multi_instance *mi,
-     unsigned int *option_types_found);
+};
 
 /*
  * Called as soon as the SSL/TLS connection is authenticated.
@@ -2280,27 +2298,81 @@ multi_connection_established(struct multi_context *m, 
struct multi_instance *mi)
         return;
     }
 
-        multi_client_connect_handler handlers[] = {
-            multi_client_connect_source_ccd,
-            multi_client_connect_call_plugin_v1,
-            multi_client_connect_call_plugin_v2,
-            multi_client_connect_call_script,
-            multi_client_connect_mda,
-            NULL
-        };
+    /* We are only called for the CAS_PENDING_x states, so we
+     * can ignore other states here */
+    bool from_deferred = (mi->context.c2.context_auth != CAS_PENDING);
 
-        unsigned int option_types_found = 0;
+    struct client_connect_defer_state *defer_state =
+        &(mi->client_connect_defer_state);
 
-    int cc_succeeded = true;     /* client connect script status */
-    int cc_succeeded_count = 0;
-    enum client_connect_return ret;
+    /* We are called for the first time */
+    if (!from_deferred)
+    {
+        defer_state->cur_handler_index = 0;
+        defer_state->option_types_found = 0;
+        /* Initially we have no handler that has returned a result */
+        mi->context.c2.context_auth = CAS_PENDING_DEFERRED;
+
+        multi_client_connect_early_setup(m, mi);
+    }
+
+    const struct client_connect_handlers *handler;
+    bool cc_succeeded = true;
 
-    multi_client_connect_early_setup(m, mi);
+    handler = &client_connect_handlers[defer_state->cur_handler_index];
 
-    for (int i = 0; cc_succeeded && handlers[i]; i++)
+    while (cc_succeeded && handler->main != NULL)
     {
-        ret = handlers[i](m, mi, &option_types_found);
-        cc_succeeded = cc_check_return(&cc_succeeded_count, ret);
+        enum client_connect_return ret;
+        if (from_deferred)
+        {
+            ret = handler->deferred(m, mi, &(defer_state->option_types_found));
+            from_deferred = false;
+        }
+        else
+        {
+            ret = handler->main(m, mi, &(defer_state->option_types_found));
+        }
+
+        if (ret == CC_RET_SUCCEEDED)
+        {
+            /*
+             * Remember that we already had at least one handler
+             * returning a result should go to into deferred state
+             */
+            mi->context.c2.context_auth = CAS_PENDING_DEFERRED_PARTIAL;
+        }
+        else if (ret == CC_RET_SKIPPED)
+        {
+            /*
+             * Move on with the next handler without modifying any
+             * other state
+             */
+        }
+        else if (ret == CC_RET_DEFERRED)
+        {
+            /*
+             * we already set client_connect_status to DEFERRED_RESULT or
+             * DEFERRED_NO_RESULT and increased index. We just return
+             * from the function as having client_connect_status
+             */
+            return;
+        }
+        else if (ret == CC_RET_FAILED)
+        {
+            /*
+             * One handler failed. We abort the chain and set the final
+             * result to failed
+             */
+            cc_succeeded = false;
+        }
+        else
+        {
+            ASSERT(0);
+        }
+
+        handler = &client_connect_handlers[defer_state->cur_handler_index];
+        (defer_state->cur_handler_index)++;
     }
 
     /*
@@ -2312,18 +2384,26 @@ multi_connection_established(struct multi_context *m, 
struct multi_instance *mi)
         msg(D_MULTI_ERRORS, "MULTI: client has been rejected due to "
             "'disable' directive");
         cc_succeeded = false;
-        cc_succeeded_count = 0;
     }
 
     if (cc_succeeded)
     {
-        multi_client_connect_late_setup(m, mi, option_types_found);
+        multi_client_connect_late_setup(m, mi,
+                                        defer_state->option_types_found);
     }
     else
     {
-        /* set context-level authentication flag */
-        mi->context.c2.context_auth =
-            cc_succeeded_count ? CAS_PARTIAL : CAS_FAILED;
+        /* set context-level authentication flag to failed but remember
+         * if had a handler succeed (for cleanup) */
+        if (mi->context.c2.context_auth == CAS_PENDING_DEFERRED_PARTIAL)
+        {
+            mi->context.c2.context_auth = CAS_PARTIAL;
+        }
+        else
+        {
+            mi->context.c2.context_auth = CAS_FAILED;
+        }
+
     }
 
     /* increment number of current authenticated clients */
@@ -2624,7 +2704,7 @@ multi_process_post(struct multi_context *m, struct 
multi_instance *mi, const uns
         {
             /* connection is "established" when SSL/TLS key negotiation 
succeeds
              * and (if specified) auth user/pass succeeds */
-            if (mi->context.c2.context_auth == CAS_PENDING
+            if (is_cas_pending(mi->context.c2.context_auth)
                 && CONNECTION_ESTABLISHED(&mi->context))
             {
                 multi_connection_established(m, mi);
@@ -3579,7 +3659,7 @@ management_client_auth(void *arg,
         {
             if (auth)
             {
-                if (mi->context.c2.context_auth == CAS_PENDING)
+                if (is_cas_pending(mi->context.c2.context_auth))
                 {
                     set_cc_config(mi, cc_config);
                     cc_config_owned = false;
@@ -3591,7 +3671,7 @@ management_client_auth(void *arg,
                 {
                     msg(D_MULTI_LOW, "MULTI: connection rejected: %s, CLI:%s", 
reason, np(client_reason));
                 }
-                if (mi->context.c2.context_auth != CAS_PENDING)
+                if (!is_cas_pending(mi->context.c2.context_auth))
                 {
                     send_auth_failed(&mi->context, client_reason); /* 
mid-session reauth failed */
                     multi_schedule_context_wakeup(m, mi);
diff --git a/src/openvpn/multi.h b/src/openvpn/multi.h
index 1d30dcc6..11da0209 100644
--- a/src/openvpn/multi.h
+++ b/src/openvpn/multi.h
@@ -62,6 +62,18 @@ struct deferred_signal_schedule_entry
     struct timeval wakeup;
 };
 
+/**
+ * Detached client connection state.  This is the state that is tracked while
+ * the client connect hooks are executed.
+ */
+struct client_connect_defer_state
+{
+    /* Index of currently executed handler.  */
+    int cur_handler_index;
+    /* Remember which option classes where processed for delayed option
+     * handling. */
+    unsigned int option_types_found;
+};
 
 /**
  * Server-mode state structure for one single VPN tunnel.
@@ -108,7 +120,7 @@ struct multi_instance {
 
     struct context context;     /**< The context structure storing state
                                  *   for this VPN tunnel. */
-
+    struct client_connect_defer_state client_connect_defer_state;
 #ifdef ENABLE_ASYNC_PUSH
     int inotify_watch; /* watch descriptor for acf */
 #endif
@@ -195,6 +207,7 @@ enum client_connect_return
 {
     CC_RET_FAILED,
     CC_RET_SUCCEEDED,
+    CC_RET_DEFERRED,
     CC_RET_SKIPPED
 };
 
diff --git a/src/openvpn/openvpn.h b/src/openvpn/openvpn.h
index 7c469b01..ccc7f118 100644
--- a/src/openvpn/openvpn.h
+++ b/src/openvpn/openvpn.h
@@ -217,6 +217,8 @@ struct context_1
 enum client_connect_status {
     CAS_SUCCEEDED=0,
     CAS_PENDING,
+    CAS_PENDING_DEFERRED,
+    CAS_PENDING_DEFERRED_PARTIAL,   /**< at least handler succeeded, no result 
yet*/
     CAS_FAILED,
     CAS_PARTIAL,        /**< Variant of CAS_FAILED: at least one
                          * client-connect script/plugin succeeded
@@ -225,6 +227,13 @@ enum client_connect_status {
                          */
 };
 
+static inline bool
+is_cas_pending(enum client_connect_status cas)
+{
+    return cas == CAS_PENDING || cas == CAS_PENDING_DEFERRED
+           || cas == CAS_PENDING_DEFERRED_PARTIAL;
+}
+
 /**
  * Level 2 %context containing state that is reset on both \c SIGHUP and
  * \c SIGUSR1 restarts.
-- 
2.26.2



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