diff options
Diffstat (limited to 'server/providers')
| -rw-r--r-- | server/providers/fail_over.c | 543 | ||||
| -rw-r--r-- | server/providers/fail_over.h | 106 |
2 files changed, 649 insertions, 0 deletions
diff --git a/server/providers/fail_over.c b/server/providers/fail_over.c new file mode 100644 index 00000000..ce94ac30 --- /dev/null +++ b/server/providers/fail_over.c @@ -0,0 +1,543 @@ +/* + 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, tv2) ((p)->last_status_change.tv_sec - (tv2).tv_sec) + +#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 *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; + + return ctx; +} + +/* + * 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; + + 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) { + server->common->server_status = SERVER_NAME_RESOLVED; + server->last_status_change.tv_sec = tv.tv_sec; + } + } + + 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; + + timeout = server->service->ctx->retry_timeout; + if (timeout != 0 && server->port_status == PORT_NOT_WORKING) { + gettimeofday(&tv, NULL); + if (STATUS_DIFF(server, tv) > timeout) { + 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; + + ret = fo_get_service(ctx, name, &service); + if (ret == EOK) { + DEBUG(1, ("Service %s already exists\n", name)); + 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); + *_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 (!strcasecmp(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; + + 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)) { + *_server = server; + return EOK; + } + service->active_server = NULL; + } + + /* Otherwise iterate through the server list. */ + DLIST_FOR_EACH(server, service->server_list) { + if (service_works(server)) { + *_server = server; + return EOK; + } + } + + return ENOENT; +} + +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; + + 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. */ + /* TODO: Enable IPv6. */ + subreq = resolv_gethostbyname_send(server->common, ev, resolv, + server->common->name, AF_INET); + if (subreq == NULL) { + ret = ENOMEM; + goto done; + } + tevent_req_set_callback(subreq, fo_resolve_service_done, server->common); + /* 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 +fo_resolve_service_done(struct tevent_req *subreq) +{ + int resolv_status; + struct resolve_service_request *request; + struct server_common *common; + + common = tevent_req_callback_data(subreq, struct server_common); + + if (common->hostent != NULL) + talloc_free(common->hostent); + resolv_gethostbyname_recv(common, subreq, &resolv_status, NULL, + &common->hostent); + talloc_free(subreq); + + if (common->hostent == NULL) { + DEBUG(1, ("Failed to resolve %s: %s\n", common->name, + resolv_strerror(resolv_status))); + } + + /* Take care of all requests for this server. */ + while ((request = common->request_list) != NULL) { + DLIST_REMOVE(common->request_list, request); + if (resolv_status) + 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; + enum tevent_req_state tstate; + uint64_t err = EIO; + + state = tevent_req_data(req, struct resolve_service_state); + + if (tevent_req_is_error(req, &tstate, &err)) + return err; + + if (server) + *server = state->server; + + return EOK; +} + +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; + } + server->common->server_status = status; + gettimeofday(&server->common->last_status_change, NULL); +} + +void +fo_set_port_status(struct fo_server *server, enum 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; +} + +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; +} diff --git a/server/providers/fail_over.h b/server/providers/fail_over.h new file mode 100644 index 00000000..b6e2f2f7 --- /dev/null +++ b/server/providers/fail_over.h @@ -0,0 +1,106 @@ +#ifndef __FAIL_OVER_H__ +#define __FAIL_OVER_H__ + +#include <stdbool.h> +#include <talloc.h> + +/* Some forward declarations that don't have to do anything with fail over. */ +struct hostent; +struct resolv_ctx; +struct tevent_context; +struct tevent_req; + +enum port_status { + PORT_NEUTRAL, /* We didn't try this port yet. */ + PORT_WORKING, /* This port was reported to work. */ + PORT_NOT_WORKING /* This port was reported to not work. */ +}; + +enum server_status { + SERVER_NAME_NOT_RESOLVED, /* We didn't yet resolved the host name. */ + SERVER_RESOLVING_NAME, /* Name resolving is in progress. */ + SERVER_NAME_RESOLVED, /* We resolved the host name but didn't try to connect. */ + SERVER_WORKING, /* We successfully connected to the server. */ + SERVER_NOT_WORKING /* We tried and failed to connect to the server. */ +}; + +struct fo_ctx; +struct fo_service; +struct fo_server; + +/* + * Create a new fail over context. The 'retry_timeout' argument specifies the + * duration in seconds of how long a server or port will be considered + * non-working after being marked as such. + */ +struct fo_ctx *fo_context_init(TALLOC_CTX *mem_ctx, + time_t retry_timeout); + +/* + * Create a new service structure for 'ctx', saving it to the location pointed + * to by '_service'. The needed memory will be allocated from 'ctx'. + * Service name will be set to 'name'. + */ +int fo_new_service(struct fo_ctx *ctx, + const char *name, + struct fo_service **_service); + +/* + * Look up service named 'name' from the 'ctx' service list. Target of + * '_service' will be set to the service if it was found. + */ +int fo_get_service(struct fo_ctx *ctx, + const char *name, + struct fo_service **_service); + +/* + * Adds a server 'name' to the 'service'. Port 'port' will be used for + * connection. If 'name' is NULL, no server resolution will be done. + */ +int fo_add_server(struct fo_service *service, + const char *name, + int port, + void *user_data); + +/* + * Request the first server from the service's list of servers. It is only + * considered if it is not marked as not working (or the retry interval already + * passed). If the server address wasn't resolved yet, it will be done. + */ +struct tevent_req *fo_resolve_service_send(TALLOC_CTX *mem_ctx, + struct tevent_context *ev, + struct resolv_ctx *resolv, + struct fo_service *service); + +int fo_resolve_service_recv(struct tevent_req *req, + struct fo_server **server); + +/* + * Set feedback about 'server'. Caller should use this to indicate a problem + * with the server itself, not only with the service on that server. This + * should be used, for example, when the IP address of the server can't be + * reached. This setting can affect other services as well, since they can + * share the same server. + */ +void fo_set_server_status(struct fo_server *server, + enum server_status status); + +/* + * Set feedback about the port status. This function should be used when + * the server itself is working but the service is not. When status is set + * to PORT_WORKING, 'server' is also marked as an "active server" for it's + * service. When the next fo_resolve_service_send() function is called, this + * server will be preferred. This will hold as long as it is not marked as + * not-working. + */ +void fo_set_port_status(struct fo_server *server, + enum port_status status); + + +void *fo_get_server_user_data(struct fo_server *server); + +int fo_get_server_port(struct fo_server *server); + +struct hostent *fo_get_server_hostent(struct fo_server *server); + +#endif /* !__FAIL_OVER_H__ */ |