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-rw-r--r--src/providers/fail_over.c651
1 files changed, 651 insertions, 0 deletions
diff --git a/src/providers/fail_over.c b/src/providers/fail_over.c
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+++ b/src/providers/fail_over.c
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+/*
+ SSSD
+
+ Fail over helper functions.
+
+ Authors:
+ Martin Nagy <mnagy@redhat.com>
+
+ Copyright (C) Red Hat, Inc 2009
+
+ 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 <sys/time.h>
+
+#include <errno.h>
+#include <stdbool.h>
+#include <strings.h>
+#include <talloc.h>
+
+#include "util/dlinklist.h"
+#include "util/refcount.h"
+#include "util/util.h"
+#include "providers/fail_over.h"
+#include "resolv/async_resolv.h"
+
+#define STATUS_DIFF(p, now) ((now).tv_sec - (p)->last_status_change.tv_sec)
+#define SERVER_NAME(s) ((s)->common ? (s)->common->name : "(no name)")
+
+#define DEFAULT_PORT_STATUS PORT_NEUTRAL
+#define DEFAULT_SERVER_STATUS SERVER_NAME_NOT_RESOLVED
+
+struct fo_ctx {
+ struct fo_service *service_list;
+ struct server_common *server_common_list;
+
+ /* Settings. */
+ time_t retry_timeout;
+};
+
+struct fo_service {
+ struct fo_service *prev;
+ struct fo_service *next;
+
+ struct fo_ctx *ctx;
+ char *name;
+ struct fo_server *active_server;
+ struct fo_server *last_tried_server;
+ struct fo_server *server_list;
+};
+
+struct fo_server {
+ struct fo_server *prev;
+ struct fo_server *next;
+
+ void *user_data;
+ int port;
+ int port_status;
+ struct fo_service *service;
+ struct timeval last_status_change;
+ struct server_common *common;
+};
+
+struct server_common {
+ REFCOUNT_COMMON;
+
+ struct server_common *prev;
+ struct server_common *next;
+
+ char *name;
+ struct hostent *hostent;
+ struct resolve_service_request *request_list;
+ int server_status;
+ struct timeval last_status_change;
+};
+
+struct resolve_service_request {
+ struct resolve_service_request *prev;
+ struct resolve_service_request *next;
+
+ struct server_common *server_common;
+ struct tevent_req *req;
+};
+
+struct status {
+ int value;
+ struct timeval last_change;
+};
+
+struct fo_ctx *
+fo_context_init(TALLOC_CTX *mem_ctx, time_t retry_timeout)
+{
+ struct fo_ctx *ctx;
+
+ ctx = talloc_zero(mem_ctx, struct fo_ctx);
+ if (ctx == NULL) {
+ DEBUG(1, ("No memory\n"));
+ return NULL;
+ }
+
+ ctx->retry_timeout = retry_timeout;
+
+ DEBUG(3, ("Created new fail over context, retry timeout is %d\n",
+ retry_timeout));
+ return ctx;
+}
+
+static const char *
+str_port_status(enum port_status status)
+{
+ switch (status) {
+ case PORT_NEUTRAL:
+ return "neutral";
+ case PORT_WORKING:
+ return "working";
+ case PORT_NOT_WORKING:
+ return "not working";
+ }
+
+ return "unknown port status";
+}
+
+static const char *
+str_server_status(enum server_status status)
+{
+ switch (status) {
+ case SERVER_NAME_NOT_RESOLVED:
+ return "name not resolved";
+ case SERVER_RESOLVING_NAME:
+ return "resolving name";
+ case SERVER_NAME_RESOLVED:
+ return "name resolved";
+ case SERVER_WORKING:
+ return "working";
+ case SERVER_NOT_WORKING:
+ return "not working";
+ }
+
+ return "unknown server status";
+}
+
+/*
+ * This function will return the status of the server. If the status was
+ * last updated a long time ago, we will first reset the status.
+ */
+static enum server_status
+get_server_status(struct fo_server *server)
+{
+ struct timeval tv;
+ time_t timeout;
+
+ if (server->common == NULL)
+ return SERVER_NAME_RESOLVED;
+
+ DEBUG(7, ("Status of server '%s' is '%s'\n", SERVER_NAME(server),
+ str_server_status(server->common->server_status)));
+
+ timeout = server->service->ctx->retry_timeout;
+ if (timeout != 0 && server->common->server_status == SERVER_NOT_WORKING) {
+ gettimeofday(&tv, NULL);
+ if (STATUS_DIFF(server->common, tv) > timeout) {
+ DEBUG(4, ("Reseting the server status of '%s'\n",
+ SERVER_NAME(server)));
+ server->common->server_status = SERVER_NAME_NOT_RESOLVED;
+ server->last_status_change.tv_sec = 0;
+ }
+ }
+
+ return server->common->server_status;
+}
+
+/*
+ * This function will return the status of the service. If the status was
+ * last updated a long time ago, we will first reset the status.
+ */
+static enum port_status
+get_port_status(struct fo_server *server)
+{
+ struct timeval tv;
+ time_t timeout;
+
+ DEBUG(7, ("Port status of port %d for server '%s' is '%s'\n", server->port,
+ SERVER_NAME(server), str_port_status(server->port_status)));
+
+ timeout = server->service->ctx->retry_timeout;
+ if (timeout != 0 && server->port_status == PORT_NOT_WORKING) {
+ gettimeofday(&tv, NULL);
+ if (STATUS_DIFF(server, tv) > timeout) {
+ DEBUG(4, ("Reseting the status of port %d for server '%s'\n",
+ server->port, SERVER_NAME(server)));
+ server->port_status = PORT_NEUTRAL;
+ server->last_status_change.tv_sec = tv.tv_sec;
+ }
+ }
+
+ return server->port_status;
+}
+
+static int
+server_works(struct fo_server *server)
+{
+ if (get_server_status(server) == SERVER_NOT_WORKING)
+ return 0;
+
+ return 1;
+}
+
+static int
+service_works(struct fo_server *server)
+{
+ if (!server_works(server))
+ return 0;
+ if (get_port_status(server) == PORT_NOT_WORKING)
+ return 0;
+
+ return 1;
+}
+
+static int
+service_destructor(struct fo_service *service)
+{
+ DLIST_REMOVE(service->ctx->service_list, service);
+ return 0;
+}
+
+int
+fo_new_service(struct fo_ctx *ctx, const char *name,
+ struct fo_service **_service)
+{
+ struct fo_service *service;
+ int ret;
+
+ DEBUG(3, ("Creating new service '%s'\n", name));
+ ret = fo_get_service(ctx, name, &service);
+ if (ret == EOK) {
+ DEBUG(5, ("Service '%s' already exists\n", name));
+ if (_service) {
+ *_service = service;
+ }
+ return EEXIST;
+ } else if (ret != ENOENT) {
+ return ret;
+ }
+
+ service = talloc_zero(ctx, struct fo_service);
+ if (service == NULL)
+ return ENOMEM;
+
+ service->name = talloc_strdup(service, name);
+ if (service->name == NULL) {
+ talloc_free(service);
+ return ENOMEM;
+ }
+
+ service->ctx = ctx;
+ DLIST_ADD(ctx->service_list, service);
+
+ talloc_set_destructor(service, service_destructor);
+ if (_service) {
+ *_service = service;
+ }
+
+ return EOK;
+}
+
+int
+fo_get_service(struct fo_ctx *ctx, const char *name,
+ struct fo_service **_service)
+{
+ struct fo_service *service;
+
+ DLIST_FOR_EACH(service, ctx->service_list) {
+ if (!strcmp(name, service->name)) {
+ *_service = service;
+ return EOK;
+ }
+ }
+
+ return ENOENT;
+}
+
+static int
+get_server_common(TALLOC_CTX *mem_ctx, struct fo_ctx *ctx, const char *name,
+ struct server_common **_common)
+{
+ struct server_common *common;
+
+ DLIST_FOR_EACH(common, ctx->server_common_list) {
+ if (!strcmp(name, common->name)) {
+ *_common = rc_reference(mem_ctx, struct server_common, common);
+ if (_common == NULL)
+ return ENOMEM;
+ return EOK;
+ }
+ }
+
+ return ENOENT;
+}
+
+static struct server_common *
+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)
+ return NULL;
+
+ common->name = talloc_strdup(common, name);
+ if (common->name == NULL) {
+ talloc_free(common);
+ return NULL;
+ }
+
+ common->prev = NULL;
+ common->next = NULL;
+ common->hostent = NULL;
+ common->request_list = NULL;
+ common->server_status = DEFAULT_SERVER_STATUS;
+ common->last_status_change.tv_sec = 0;
+ common->last_status_change.tv_usec = 0;
+
+ DLIST_ADD_END(ctx->server_common_list, common, struct server_common *);
+ return common;
+}
+
+int
+fo_add_server(struct fo_service *service, const char *name, int port,
+ void *user_data)
+{
+ struct fo_server *server;
+ int ret;
+
+ DEBUG(3, ("Adding new server '%s', to service '%s'\n",
+ name ? name : "(no name)", service->name));
+ DLIST_FOR_EACH(server, service->server_list) {
+ if (server->port != port || server->user_data != user_data)
+ continue;
+ if (name == NULL && server->common == NULL) {
+ return EEXIST;
+ } else if (name != NULL && server->common != NULL) {
+ if (!strcmp(name, server->common->name))
+ return EEXIST;
+ }
+ }
+
+ server = talloc_zero(service, struct fo_server);
+ if (server == NULL)
+ return ENOMEM;
+
+ server->port = port;
+ server->user_data = user_data;
+ server->service = service;
+ server->port_status = DEFAULT_PORT_STATUS;
+
+ if (name != NULL) {
+ ret = get_server_common(server, service->ctx, name, &server->common);
+ if (ret == ENOENT) {
+ server->common = create_server_common(server, service->ctx, name);
+ if (server->common == NULL) {
+ talloc_free(server);
+ return ENOMEM;
+ }
+ } else if (ret != EOK) {
+ talloc_free(server);
+ return ret;
+ }
+ }
+
+ DLIST_ADD_END(service->server_list, server, struct fo_server *);
+
+ return EOK;
+}
+
+static int
+get_first_server_entity(struct fo_service *service, struct fo_server **_server)
+{
+ struct fo_server *server;
+
+ /* If we already have a working server, use that one. */
+ server = service->active_server;
+ if (server != NULL) {
+ if (service_works(server)) {
+ goto done;
+ }
+ service->active_server = NULL;
+ }
+
+ /*
+ * Otherwise iterate through the server list.
+ */
+
+ /* First, try servers after the last one we tried. */
+ if (service->last_tried_server != NULL) {
+ DLIST_FOR_EACH(server, service->last_tried_server->next) {
+ if (service_works(server)) {
+ goto done;
+ }
+ }
+ }
+
+ /* If none were found, try at the start. */
+ DLIST_FOR_EACH(server, service->server_list) {
+ if (service_works(server)) {
+ goto done;
+ }
+ if (server == service->last_tried_server) {
+ break;
+ }
+ }
+
+ service->last_tried_server = NULL;
+ return ENOENT;
+
+done:
+ service->last_tried_server = server;
+ *_server = server;
+ return EOK;
+}
+
+static int
+resolve_service_request_destructor(struct resolve_service_request *request)
+{
+ DLIST_REMOVE(request->server_common->request_list, request);
+ return 0;
+}
+
+static int
+set_lookup_hook(struct fo_server *server, struct tevent_req *req)
+{
+ struct resolve_service_request *request;
+
+ request = talloc(req, struct resolve_service_request);
+ if (request == NULL) {
+ DEBUG(1, ("No memory\n"));
+ talloc_free(request);
+ return ENOMEM;
+ }
+ request->server_common = server->common;
+ request->req = req;
+ DLIST_ADD(server->common->request_list, request);
+ talloc_set_destructor(request, resolve_service_request_destructor);
+
+ return EOK;
+}
+
+/*******************************************************************
+ * Get server to connect to. *
+ *******************************************************************/
+
+struct resolve_service_state {
+ struct fo_server *server;
+};
+
+static void fo_resolve_service_done(struct tevent_req *subreq);
+
+struct tevent_req *
+fo_resolve_service_send(TALLOC_CTX *mem_ctx, struct tevent_context *ev,
+ struct resolv_ctx *resolv, struct fo_service *service)
+{
+ int ret;
+ struct fo_server *server;
+ struct tevent_req *req;
+ struct tevent_req *subreq;
+ struct resolve_service_state *state;
+
+ DEBUG(4, ("Trying to resolve service '%s'\n", service->name));
+ req = tevent_req_create(mem_ctx, &state, struct resolve_service_state);
+ if (req == NULL)
+ return NULL;
+
+ ret = get_first_server_entity(service, &server);
+ if (ret != EOK) {
+ DEBUG(1, ("No available servers for service '%s'\n", service->name));
+ goto done;
+ }
+
+ state->server = server;
+
+ if (server->common == NULL) {
+ /* This server doesn't have a name, we don't do name resolution. */
+ tevent_req_done(req);
+ tevent_req_post(req, ev);
+ return req;
+ }
+
+ switch (get_server_status(server)) {
+ case SERVER_NAME_NOT_RESOLVED: /* Request name resolution. */
+ subreq = resolv_gethostbyname_send(server->common, ev, resolv,
+ server->common->name);
+ if (subreq == NULL) {
+ ret = ENOMEM;
+ goto done;
+ }
+ tevent_req_set_callback(subreq, fo_resolve_service_done, server->common);
+ fo_set_server_status(server, SERVER_RESOLVING_NAME);
+ /* FALLTHROUGH */
+ case SERVER_RESOLVING_NAME:
+ /* Name resolution is already under way. Just add ourselves into the
+ * waiting queue so we get notified after the operation is finished. */
+ ret = set_lookup_hook(server, req);
+ if (ret != EOK)
+ goto done;
+ break;
+ default: /* The name is already resolved. Return immediately. */
+ tevent_req_done(req);
+ tevent_req_post(req, ev);
+ break;
+ }
+
+done:
+ if (ret != EOK) {
+ tevent_req_error(req, ret);
+ tevent_req_post(req, ev);
+ }
+ return req;
+}
+
+static void set_server_common_status(struct server_common *common,
+ enum server_status status);
+
+static void
+fo_resolve_service_done(struct tevent_req *subreq)
+{
+ int resolv_status;
+ struct resolve_service_request *request;
+ struct server_common *common;
+ int ret;
+
+ common = tevent_req_callback_data(subreq, struct server_common);
+
+ if (common->hostent != NULL) {
+ talloc_zfree(common->hostent);
+ }
+
+ ret = resolv_gethostbyname_recv(subreq, common,
+ &resolv_status, NULL, &common->hostent);
+ talloc_free(subreq);
+ if (ret != EOK) {
+ DEBUG(1, ("Failed to resolve server '%s': %s\n", common->name,
+ resolv_strerror(resolv_status)));
+ set_server_common_status(common, SERVER_NOT_WORKING);
+ } else {
+ set_server_common_status(common, SERVER_NAME_RESOLVED);
+ }
+
+ /* Take care of all requests for this server. */
+ while ((request = common->request_list) != NULL) {
+ DLIST_REMOVE(common->request_list, request);
+ if (resolv_status) {
+ /* FIXME FIXME: resolv_status is an ARES error.
+ * but any caller will expect classic error codes.
+ * also the send() function may return ENOENT, so this mix
+ * IS explosive (ENOENT = 2 = ARES_EFORMER) */
+ tevent_req_error(request->req, resolv_status);
+ } else {
+ tevent_req_done(request->req);
+ }
+ }
+}
+
+int
+fo_resolve_service_recv(struct tevent_req *req, struct fo_server **server)
+{
+ struct resolve_service_state *state;
+
+ state = tevent_req_data(req, struct resolve_service_state);
+
+ /* always return the server if asked for, otherwise the caller
+ * cannot mark it as faulty in case we return an error */
+ if (server)
+ *server = state->server;
+
+ TEVENT_REQ_RETURN_ON_ERROR(req);
+
+ return EOK;
+}
+
+static void
+set_server_common_status(struct server_common *common,
+ enum server_status status)
+{
+ DEBUG(4, ("Marking server '%s' as '%s'\n", common->name,
+ str_server_status(status)));
+
+ common->server_status = status;
+ gettimeofday(&common->last_status_change, NULL);
+}
+
+void
+fo_set_server_status(struct fo_server *server, enum server_status status)
+{
+ if (server->common == NULL) {
+ DEBUG(1, ("Bug: Trying to set server status of a name-less server\n"));
+ return;
+ }
+
+ set_server_common_status(server->common, status);
+}
+
+void
+fo_set_port_status(struct fo_server *server, enum port_status status)
+{
+ DEBUG(4, ("Marking port %d of server '%s' as '%s'\n", server->port,
+ SERVER_NAME(server), str_port_status(status)));
+
+ server->port_status = status;
+ gettimeofday(&server->last_status_change, NULL);
+ if (status == PORT_WORKING) {
+ fo_set_server_status(server, SERVER_WORKING);
+ server->service->active_server = server;
+ }
+}
+
+void *
+fo_get_server_user_data(struct fo_server *server)
+{
+ return server->user_data;
+}
+
+int
+fo_get_server_port(struct fo_server *server)
+{
+ return server->port;
+}
+
+const char *fo_get_server_name(struct fo_server *server)
+{
+ return server->common->name;
+}
+
+struct hostent *
+fo_get_server_hostent(struct fo_server *server)
+{
+ if (server->common == NULL) {
+ DEBUG(1, ("Bug: Trying to get hostent from a name-less server\n"));
+ return NULL;
+ }
+ return server->common->hostent;
+}