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.

Patch V7: move defferred bool into client connect handler calls, switch
          to switch case

Signed-off-by: Arne Schwabe <a...@rfc2549.org>
---
 src/openvpn/multi.c   | 157 +++++++++++++++++++++++++++++-------------
 src/openvpn/multi.h   |  15 +++-
 src/openvpn/openvpn.h |   9 +++
 3 files changed, 132 insertions(+), 49 deletions(-)

diff --git a/src/openvpn/multi.c b/src/openvpn/multi.c
index 97b7df16..9128798d 100644
--- a/src/openvpn/multi.c
+++ b/src/openvpn/multi.c
@@ -1713,8 +1713,11 @@ multi_client_connect_post_plugin(struct multi_context *m,
 enum client_connect_return
 multi_client_connect_mda(struct multi_context *m,
                          struct multi_instance *mi,
+                         bool deferred,
                          unsigned int *option_types_found)
 {
+    /* We never return CC_RET_DEFERRED */
+    ASSERT(!deferred);
     enum client_connect_return ret = CC_RET_SKIPPED;
 #ifdef MANAGEMENT_DEF_AUTH
     if (mi->cc_config)
@@ -1854,8 +1857,13 @@ multi_client_set_protocol_options(struct context *c)
 static enum client_connect_return
 multi_client_connect_call_plugin_v1(struct multi_context *m,
                                     struct multi_instance *mi,
+                                    bool deferred,
                                     unsigned int *option_types_found)
 {
+    if (deferred)
+    {
+        return CC_RET_FAILED;
+    }
     enum client_connect_return ret = CC_RET_SKIPPED;
 #ifdef ENABLE_PLUGIN
     ASSERT(m);
@@ -1907,8 +1915,13 @@ cleanup:
 static enum client_connect_return
 multi_client_connect_call_plugin_v2(struct multi_context *m,
                                     struct multi_instance *mi,
+                                    bool deferred,
                                     unsigned int *option_types_found)
 {
+    if (deferred)
+    {
+        return CC_RET_FAILED;
+    }
     enum client_connect_return ret = CC_RET_SKIPPED;
 #ifdef ENABLE_PLUGIN
     ASSERT(m);
@@ -1949,8 +1962,13 @@ multi_client_connect_call_plugin_v2(struct multi_context 
*m,
 static enum client_connect_return
 multi_client_connect_call_script(struct multi_context *m,
                                  struct multi_instance *mi,
+                                 bool deferred,
                                  unsigned int *option_types_found)
 {
+    if (deferred)
+    {
+        return CC_RET_FAILED;
+    }
     ASSERT(m);
     ASSERT(mi);
 
@@ -2173,8 +2191,12 @@ multi_client_connect_early_setup(struct multi_context *m,
 static enum client_connect_return
 multi_client_connect_source_ccd(struct multi_context *m,
                                 struct multi_instance *mi,
+                                bool deferred,
                                 unsigned int *option_types_found)
 {
+    /* Since we never return a CC_RET_DEFERRED, this indicates a serious
+     * problem */
+    ASSERT(!deferred);
     enum client_connect_return ret = CC_RET_SKIPPED;
     if (mi->context.options.client_config_dir)
     {
@@ -2225,32 +2247,18 @@ 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)
-{
-    if (ret == CC_RET_SUCCEEDED)
-    {
-        (*cc_succeeded_count)++;
-        return true;
-    }
-    else if (ret == CC_RET_FAILED)
-    {
-        return false;
-    }
-    else if (ret == CC_RET_SKIPPED)
-    {
-        return true;
-    }
-    else
-    {
-        ASSERT(0);
-    }
-}
-
 typedef enum client_connect_return (*multi_client_connect_handler)
     (struct multi_context *m, struct multi_instance *mi,
-     unsigned int *option_types_found);
+    bool from_deferred, unsigned int *option_types_found);
+
+static const multi_client_connect_handler client_connect_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,
+};
 
 /*
  * Called as soon as the SSL/TLS connection is authenticated.
@@ -2280,27 +2288,74 @@ 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;
+    int *cur_handler_index = &mi->client_connect_defer_state.cur_handler_index;
+    unsigned int *option_types_found =
+        &mi->client_connect_defer_state.option_types_found;
 
-    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)
+    {
+        *cur_handler_index = 0;
+        *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);
+        multi_client_connect_early_setup(m, mi);
+    }
 
-    for (int i = 0; cc_succeeded && handlers[i]; i++)
+    bool cc_succeeded = true;
+
+    while (cc_succeeded
+           && client_connect_handlers[*cur_handler_index] != NULL)
     {
-        ret = handlers[i](m, mi, &option_types_found);
-        cc_succeeded = cc_check_return(&cc_succeeded_count, ret);
+        enum client_connect_return ret;
+        ret = client_connect_handlers[*cur_handler_index](m, mi, from_deferred,
+                                                          option_types_found);
+
+        from_deferred = false;
+
+        switch (ret)
+        {
+            case 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;
+                break;
+
+            case CC_RET_SKIPPED:
+                /*
+                 * Move on with the next handler without modifying any
+                 * other state
+                 */
+                break;
+
+            case CC_RET_DEFERRED:
+                /*
+                 * we already set client_connect_status to DEFERRED_RESULT or
+                 * DEFERRED_NO_RESULT. We just return
+                 * from the function as having client_connect_status
+                 */
+                return;
+
+            case CC_RET_FAILED:
+                /*
+                 * One handler failed. We abort the chain and set the final
+                 * result to failed
+                 */
+                cc_succeeded = false;
+                break;
+
+            default:
+                ASSERT(0);
+        }
+
+        (*cur_handler_index)++;
     }
 
     /*
@@ -2312,18 +2367,24 @@ 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, *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 +2685,7 @@ 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 +3640,7 @@ 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 +3652,7 @@ 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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