FO: Use refcount to keep track of servers returned to callers

Resolves:
    https://fedorahosted.org/sssd/ticket/2829

Reviewed-by: Pavel Březina <pbrezina@redhat.com>

1 files changed, 76 insertions, 19 deletions

diff --git a/src/providers/fail_over.c b/src/providers/fail_over.c
index b309f1c68..24aed9dfa 100644
--- a/src/providers/fail_over.c
+++ b/src/providers/fail_over.c
@@ -79,6 +79,8 @@ struct fo_service {
 };
 
 struct fo_server {
+    REFCOUNT_COMMON;
+
     struct fo_server *prev;
     struct fo_server *next;
 
@@ -90,6 +92,8 @@ struct fo_server {
     struct fo_service *service;
     struct timeval last_status_change;
     struct server_common *common;
+
+    TALLOC_CTX *fo_internal_owner;
 };
 
 struct server_common {
@@ -217,6 +221,15 @@ int fo_is_srv_lookup(struct fo_server *s)
     return s && s->srv_data;
 }
 
+static void fo_server_free(struct fo_server *server)
+{
+    if (server == NULL) {
+        return;
+    }
+
+    talloc_free(server->fo_internal_owner);
+}
+
 static struct fo_server *
 collapse_srv_lookup(struct fo_server **_server)
 {
@@ -231,12 +244,12 @@ collapse_srv_lookup(struct fo_server **_server)
         while (server->prev && server->prev->srv_data == meta->srv_data) {
             tmp = server->prev;
             DLIST_REMOVE(server->service->server_list, tmp);
-            talloc_zfree(tmp);
+            fo_server_free(tmp);
         }
         while (server->next && server->next->srv_data == meta->srv_data) {
             tmp = server->next;
             DLIST_REMOVE(server->service->server_list, tmp);
-            talloc_zfree(tmp);
+            fo_server_free(tmp);
         }
 
         if (server == server->service->active_server) {
@@ -249,7 +262,7 @@ collapse_srv_lookup(struct fo_server **_server)
         /* add back the meta server to denote SRV lookup */
         DLIST_ADD_AFTER(server->service->server_list, meta, server);
         DLIST_REMOVE(server->service->server_list, server);
-        talloc_zfree(server);
+        fo_server_free(server);
     }
 
     meta->srv_data->srv_lookup_status = SRV_NEUTRAL;
@@ -502,8 +515,9 @@ create_server_common(TALLOC_CTX *mem_ctx, struct fo_ctx *ctx, const char *name)
     struct server_common *common;
 
     common = rc_alloc(mem_ctx, struct server_common);
-    if (common == NULL)
+    if (common == NULL) {
         return NULL;
+    }
 
     common->name = talloc_strdup(common, name);
     if (common->name == NULL) {
@@ -524,6 +538,41 @@ create_server_common(TALLOC_CTX *mem_ctx, struct fo_ctx *ctx, const char *name)
     return common;
 }
 
+static struct fo_server *
+fo_server_alloc(struct fo_service *service, int port,
+                void *user_data, bool primary)
+{
+    static struct fo_server *server;
+    TALLOC_CTX *server_owner;
+
+    server_owner = talloc_new(service);
+    if (server_owner == NULL) {
+        return NULL;
+    }
+
+    server = rc_alloc(server_owner, struct fo_server);
+    if (server == NULL) {
+        return NULL;
+    }
+
+    server->fo_internal_owner = server_owner;
+
+    server->common = NULL;
+    server->next = NULL;
+    server->prev = NULL;
+    server->srv_data = NULL;
+    server->last_status_change.tv_sec = 0;
+    server->last_status_change.tv_usec = 0;
+
+    server->port = port;
+    server->user_data = user_data;
+    server->service = service;
+    server->port_status = DEFAULT_PORT_STATUS;
+    server->primary = primary;
+
+    return server;
+}
+
 int
 fo_add_srv_server(struct fo_service *service, const char *srv,
                   const char *discovery_domain, const char *sssd_domain,
@@ -557,14 +606,11 @@ fo_add_srv_server(struct fo_service *service, const char *srv,
         }
     }
 
-    server = talloc_zero(service, struct fo_server);
-    if (server == NULL)
+    /* SRV servers are always primary */
+    server = fo_server_alloc(service, 0, user_data, true);
+    if (server == NULL) {
         return ENOMEM;
-
-    server->user_data = user_data;
-    server->service = service;
-    server->port_status = DEFAULT_PORT_STATUS;
-    server->primary = true; /* SRV servers are never back up */
+    }
 
     /* add the SRV-specific data */
     server->srv_data = talloc_zero(service, struct srv_data);
@@ -608,7 +654,7 @@ create_fo_server(struct fo_service *service, const char *name,
     struct fo_server *server;
     int ret;
 
-    server = talloc_zero(service, struct fo_server);
+    server = fo_server_alloc(service, port, user_data, primary);
     if (server == NULL)
         return NULL;
 
@@ -623,11 +669,11 @@ create_fo_server(struct fo_service *service, const char *name,
         if (ret == ENOENT) {
             server->common = create_server_common(server, service->ctx, name);
             if (server->common == NULL) {
-                talloc_free(server);
+                fo_server_free(server);
                 return NULL;
             }
         } else if (ret != EOK) {
-            talloc_free(server);
+            fo_server_free(server);
             return NULL;
         }
     }
@@ -760,7 +806,6 @@ static errno_t fo_add_server_list(struct fo_service *service,
         server = create_fo_server(service, servers[i].host, servers[i].port,
                                   user_data, primary);
         if (server == NULL) {
-            talloc_free(srv_list);
             return ENOMEM;
         }
 
@@ -769,7 +814,7 @@ static errno_t fo_add_server_list(struct fo_service *service,
         ret = fo_add_server_to_list(&srv_list, service->server_list,
                                     server, service->name);
         if (ret != EOK) {
-            talloc_zfree(server);
+            fo_server_free(server);
             continue;
         }
 
@@ -803,12 +848,20 @@ fo_add_server(struct fo_service *service, const char *name, int port,
     ret = fo_add_server_to_list(&service->server_list, service->server_list,
                                 server, service->name);
     if (ret != EOK) {
-        talloc_free(server);
+        fo_server_free(server);
     }
 
     return ret;
 }
 
+void fo_ref_server(TALLOC_CTX *ref_ctx,
+                   struct fo_server *server)
+{
+    if (server) {
+        rc_reference(ref_ctx, struct fo_server, server);
+    }
+}
+
 static int
 get_first_server_entity(struct fo_service *service, struct fo_server **_server)
 {
@@ -1150,7 +1203,9 @@ fo_resolve_service_done(struct tevent_req *subreq)
 }
 
 int
-fo_resolve_service_recv(struct tevent_req *req, struct fo_server **server)
+fo_resolve_service_recv(struct tevent_req *req,
+                        TALLOC_CTX *ref_ctx,
+                        struct fo_server **server)
 {
     struct resolve_service_state *state;
 
@@ -1158,8 +1213,10 @@ fo_resolve_service_recv(struct tevent_req *req, struct fo_server **server)
 
     /* always return the server if asked for, otherwise the caller
      * cannot mark it as faulty in case we return an error */
-    if (server)
+    if (server != NULL) {
+        fo_ref_server(ref_ctx, state->server);
         *server = state->server;
+    }
 
     TEVENT_REQ_RETURN_ON_ERROR(req);