[Openvpn-devel,v7,2/6] client-connect: Add deferred support to the client-connect script handler

diff --git a/src/openvpn/multi.c b/src/openvpn/multi.c
index 9128798d..e26daeea 100644
--- a/src/openvpn/multi.c
+++ b/src/openvpn/multi.c
@@ -1854,6 +1854,168 @@  multi_client_set_protocol_options(struct context *c)
     }
 }
 
+/**
+ * Delete the temporary file for the return value of client connect
+ * It also removes it from it from client_connect_defer_state and
+ * environment
+ */
+static void
+ccs_delete_deferred_ret_file(struct multi_instance *mi)
+{
+    struct client_connect_defer_state *ccs = &(mi->client_connect_defer_state);
+    if (ccs->deferred_ret_file)
+    {
+        setenv_del(mi->context.c2.es, "client_connect_deferred_file");
+        if (!platform_unlink(ccs->deferred_ret_file))
+        {
+            msg(D_MULTI_ERRORS, "MULTI: problem deleting temporary file: %s",
+                ccs->deferred_ret_file);
+        }
+        free(ccs->deferred_ret_file);
+        ccs->deferred_ret_file = NULL;
+    }
+}
+
+/**
+ * Create a temporary file for the return value of client connect
+ * and puts it into the client_connect_defer_state and environment
+ * as "client_connect_deferred_file"
+ *
+ * @return boolean value if creation was successfull
+ */
+static bool
+ccs_gen_deferred_ret_file(struct multi_instance *mi)
+{
+    struct client_connect_defer_state *ccs = &(mi->client_connect_defer_state);
+    struct gc_arena gc = gc_new();
+    const char *fn;
+
+    if (ccs->deferred_ret_file)
+    {
+        ccs_delete_deferred_ret_file(mi);
+    }
+
+    fn = platform_create_temp_file(mi->context.options.tmp_dir, "ccr", &gc);
+    if (!fn)
+    {
+        gc_free(&gc);
+        return false;
+    }
+    ccs->deferred_ret_file = string_alloc(fn, NULL);
+
+    setenv_str(mi->context.c2.es, "client_connect_deferred_file",
+               ccs->deferred_ret_file);
+
+    gc_free(&gc);
+    return true;
+}
+
+/**
+ * Tests whether the deferred return value file exists and returns the
+ * contained return value.
+ *
+ * @return CC_RET_SKIPPED if the file does not exist or is empty.
+ *         CC_RET_DEFERRED, CC_RET_SUCCEEDED or CC_RET_FAILED depending on
+ *         the value stored in the file.
+ */
+static enum client_connect_return
+ccs_test_deferred_ret_file(struct multi_instance *mi)
+{
+    struct client_connect_defer_state *ccs = &(mi->client_connect_defer_state);
+    enum client_connect_return ret = CC_RET_SKIPPED;
+    FILE *fp = fopen(ccs->deferred_ret_file, "r");
+    if (fp)
+    {
+        const int c = fgetc(fp);
+        switch (c)
+        {
+            case '0':
+                ret = CC_RET_FAILED;
+                break;
+
+            case '1':
+                ret = CC_RET_SUCCEEDED;
+                break;
+
+            case '2':
+                ret = CC_RET_DEFERRED;
+                break;
+
+            case EOF:
+                if (feof(fp))
+                {
+                    ret = CC_RET_SKIPPED;
+                    break;
+                }
+
+            /* Not EOF, but other error fall through to error state */
+            default:
+                /* We received an unknown/unexpected value.  Assume failure. */
+                msg(M_WARN, "WARNING: Unknown/unexcepted value in deferred"
+                    "client-connect resultfile");
+                ret = CC_RET_FAILED;
+        }
+        fclose(fp);
+    }
+    return ret;
+}
+
+/**
+ * Deletes the temporary file for the config directives of the  client connect
+ * script and removes it into the client_connect_defer_state and environment
+ *
+ */
+static void
+ccs_delete_config_file(struct multi_instance *mi)
+{
+    struct client_connect_defer_state *ccs = &(mi->client_connect_defer_state);
+    if (ccs->config_file)
+    {
+        setenv_del(mi->context.c2.es, "client_connect_config_file");
+        if (!platform_unlink(ccs->config_file))
+        {
+            msg(D_MULTI_ERRORS, "MULTI: problem deleting temporary file: %s",
+                ccs->config_file);
+        }
+        free(ccs->config_file);
+        ccs->config_file = NULL;
+    }
+}
+
+/**
+ * Create a temporary file for the config directives of the  client connect
+ * script and puts it into the client_connect_defer_state and environment
+ * as "client_connect_config_file"
+ *
+ * @return boolean value if creation was successfull
+ */
+static bool
+ccs_gen_config_file(struct multi_instance *mi)
+{
+    struct client_connect_defer_state *ccs = &(mi->client_connect_defer_state);
+    struct gc_arena gc = gc_new();
+    const char *fn;
+
+    if (ccs->config_file)
+    {
+        ccs_delete_config_file(mi);
+    }
+
+    fn = platform_create_temp_file(mi->context.options.tmp_dir, "cc", &gc);
+    if (!fn)
+    {
+        gc_free(&gc);
+        return false;
+    }
+    ccs->config_file = string_alloc(fn, NULL);
+
+    setenv_str(mi->context.c2.es, "client_connect_config_file",
+               ccs->config_file);
+
+    gc_free(&gc);
+    return true;
+}
+
 static enum client_connect_return
 multi_client_connect_call_plugin_v1(struct multi_context *m,
                                     struct multi_instance *mi,
@@ -1954,7 +2116,39 @@  multi_client_connect_call_plugin_v2(struct multi_context *m,
     return ret;
 }
 
+static enum client_connect_return
+multi_client_connect_script_deferred(struct multi_context *m,
+                                     struct multi_instance *mi,
+                                     unsigned int *option_types_found)
+{
+    ASSERT(mi);
+    ASSERT(option_types_found);
+    struct client_connect_defer_state *ccs = &(mi->client_connect_defer_state);
+    enum client_connect_return ret = CC_RET_SKIPPED;
+
+    ret = ccs_test_deferred_ret_file(mi);
 
+    if (ret == CC_RET_SKIPPED)
+    {
+        /*
+         * Skipped and deferred are equivalent in this context.
+         * skipped means that the called program has not yet
+         * written a return status implicitly needing more time
+         * while deferred is the explicit notification that it
+         * needs more time
+         */
+        ret = CC_RET_DEFERRED;
+    }
+
+    if (ret != CC_RET_DEFERRED)
+    {
+        ccs_delete_deferred_ret_file(mi);
+        multi_client_connect_post(m, mi, ccs->config_file,
+                                  option_types_found);
+        ccs_delete_config_file(mi);
+    }
+    return ret;
+}
 
 /**
  * Runs the --client-connect script if one is defined.
@@ -1967,48 +2161,54 @@  multi_client_connect_call_script(struct multi_context *m,
 {
     if (deferred)
     {
-        return CC_RET_FAILED;
+        return multi_client_connect_script_deferred(m, mi, option_types_found);
     }
     ASSERT(m);
     ASSERT(mi);
 
     enum client_connect_return ret = CC_RET_SKIPPED;
+    struct client_connect_defer_state *ccs = &(mi->client_connect_defer_state);
 
     if (mi->context.options.client_connect_script)
     {
         struct argv argv = argv_new();
         struct gc_arena gc = gc_new();
-        const char *dc_file = NULL;
 
         setenv_str(mi->context.c2.es, "script_type", "client-connect");
 
-        dc_file = platform_create_temp_file(mi->context.options.tmp_dir,
-                                            "cc", &gc);
-        if (!dc_file)
+        if (!ccs_gen_config_file(mi)
+            || !ccs_gen_deferred_ret_file(mi))
         {
             ret = CC_RET_FAILED;
             goto cleanup;
         }
 
         argv_parse_cmd(&argv, mi->context.options.client_connect_script);
-        argv_printf_cat(&argv, "%s", dc_file);
+        argv_printf_cat(&argv, "%s", ccs->config_file);
 
         if (openvpn_run_script(&argv, mi->context.c2.es, 0, "--client-connect"))
         {
-            multi_client_connect_post(m, mi, dc_file, option_types_found);
-            ret = CC_RET_SUCCEEDED;
+            if (ccs_test_deferred_ret_file(mi) == CC_RET_DEFERRED)
+            {
+                ret = CC_RET_DEFERRED;
+            }
+            else
+            {
+                multi_client_connect_post(m, mi, ccs->config_file,
+                                          option_types_found);
+                ret = CC_RET_SUCCEEDED;
+            }
         }
         else
         {
             ret = CC_RET_FAILED;
         }
-
-        if (!platform_unlink(dc_file))
+cleanup:
+        if (ret != CC_RET_DEFERRED)
         {
-            msg(D_MULTI_ERRORS, "MULTI: problem deleting temporary file: %s",
-                dc_file);
+            ccs_delete_config_file(mi);
+            ccs_delete_deferred_ret_file(mi);
         }
-cleanup:
         argv_free(&argv);
         gc_free(&gc);
     }
diff --git a/src/openvpn/multi.h b/src/openvpn/multi.h
index 11da0209..3ebf6b9f 100644
--- a/src/openvpn/multi.h
+++ b/src/openvpn/multi.h
@@ -73,6 +73,18 @@  struct client_connect_defer_state
     /* Remember which option classes where processed for delayed option
      * handling. */
     unsigned int option_types_found;
+
+    /**
+     * The temporrary file name that contains the return status of the
+     * client-connect script if it exits with defer as status
+     */
+    char *deferred_ret_file;
+
+    /**
+     * The temporary file name that contains the config directives
+     * returned by the client-connect script
+     */
+    char *config_file;
 };
 
 /**