DP: Introduce new interface for backend

Terminology:
* Backend: Implemenation of domain
* Data Provider: interface between backend and responders
* Module: ldap/ipa/ad/... dlopened library that implements dp interface
* Target: id/autofs/sudo/... functionality of module

Benefits over current code:
* data provider is a black box completely separated from backend
* method handlers are just simple tevent requests on backend side
* no need of spy on be_client
* simplified and error proof adding of new responders
* simplified adding of new methods
* reply to D-Bus message is completely handled by DP code
* each target can have several methods defined
* properties can be added on objects
* each method can have output parameters
* modules now support constructor
* improved debugging
* clear memory hierarchy
* ability to chain requests
* type safe private data

Reviewed-by: Sumit Bose <sbose@redhat.com>
Reviewed-by: Jakub Hrozek <jhrozek@redhat.com>
Reviewed-by: Lukáš Slebodník <lslebodn@redhat.com>

1 files changed, 122 insertions, 0 deletions

diff --git a/src/providers/data_provider/dp_methods.c b/src/providers/data_provider/dp_methods.c
new file mode 100644
index 000000000..e4290beee
--- /dev/null
+++ b/src/providers/data_provider/dp_methods.c
@@ -0,0 +1,122 @@
+/*
+    Authors:
+        Pavel Březina <pbrezina@redhat.com>
+
+    Copyright (C) 2016 Red Hat
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <talloc.h>
+
+#include "config.h"
+#include "providers/data_provider/dp.h"
+#include "providers/data_provider/dp_private.h"
+#include "providers/backend.h"
+#include "util/util.h"
+
+void _dp_set_method(struct dp_method *methods,
+                    enum dp_methods method,
+                    dp_req_send_fn send_fn,
+                    dp_req_recv_fn recv_fn,
+                    void *method_data,
+                    const char *method_dtype,
+                    const char *request_dtype,
+                    const char *output_dtype,
+                    uint32_t output_size)
+{
+    if (method >= DP_METHOD_SENTINEL) {
+        DEBUG(SSSDBG_CRIT_FAILURE, "Bug: invalid method %d\n", method);
+        return;
+    }
+
+    /* Each method can be set only once, if we attempt to set it twice it
+     * is a bug in module initialization. */
+    if (methods[method].send_fn != NULL) {
+        DEBUG(SSSDBG_CRIT_FAILURE, "Bug: method %d is already set!\n", method);
+        return;
+    }
+
+    if (send_fn == NULL || recv_fn == NULL || method_dtype == NULL
+            || request_dtype == NULL || output_dtype == NULL) {
+        DEBUG(SSSDBG_CRIT_FAILURE, "Bug: one or more required parameter was "
+              "not provided for method %d\n", method);
+        return;
+    }
+
+    methods[method].send_fn = send_fn;
+    methods[method].recv_fn = recv_fn;
+    methods[method].method_data = method_data;
+
+    methods[method].method_dtype = method_dtype;
+    methods[method].request_dtype = request_dtype;
+    methods[method].output_dtype = output_dtype;
+    methods[method].output_size = output_size;
+}
+
+bool dp_method_enabled(struct data_provider *provider,
+                       enum dp_targets target,
+                       enum dp_methods method)
+{
+    struct dp_target *dp_target;
+
+    if (target >= DP_TARGET_SENTINEL || method >= DP_METHOD_SENTINEL) {
+        DEBUG(SSSDBG_CRIT_FAILURE, "Bug: Invalid target or method ID\n");
+        return false;
+    }
+
+    dp_target = provider->targets[target];
+    if (dp_target == NULL || dp_target->initialized == false) {
+        DEBUG(SSSDBG_TRACE_FUNC, "Target %s is not configured\n",
+              dp_target_to_string(target));
+        return false;
+    }
+
+    if (dp_target->methods[method].send_fn == NULL) {
+        return false;
+    }
+
+    return true;
+}
+
+errno_t dp_find_method(struct data_provider *provider,
+                       enum dp_targets target,
+                       enum dp_methods method,
+                       struct dp_method **_execute)
+{
+    struct dp_method *execute;
+
+    if (target >= DP_TARGET_SENTINEL || method >= DP_METHOD_SENTINEL) {
+        DEBUG(SSSDBG_CRIT_FAILURE, "Bug: Invalid target or method ID\n");
+        return ERR_INTERNAL;
+    }
+
+    if (!dp_target_initialized(provider->targets, target)) {
+        DEBUG(SSSDBG_CRIT_FAILURE, "Target [%s] is not initialized\n",
+              dp_target_to_string(target));
+        return ERR_MISSING_DP_TARGET;
+    }
+
+    execute = &provider->targets[target]->methods[method];
+    if (execute->send_fn == NULL || execute->recv_fn == NULL) {
+        DEBUG(SSSDBG_CRIT_FAILURE,
+              "Bug: Invalid combination of target [%s] and method [%d]\n",
+              dp_target_to_string(target), method);
+        return ERR_INTERNAL;
+    }
+
+    *_execute = execute;
+
+    return EOK;
+}