Add initial failover support for ldap and ipa

The retun values are still not directly used with ldap libraries that still do
their own name resolution, but this patch introduces a very basic framework to
have a multiple providers in one domain use and share a single failover
service if they want to.

1 files changed, 358 insertions, 0 deletions

diff --git a/server/providers/data_provider_fo.c b/server/providers/data_provider_fo.c
new file mode 100644
index 000000000..ebf92a43a
--- /dev/null
+++ b/server/providers/data_provider_fo.c
@@ -0,0 +1,358 @@
+/*
+    SSSD
+
+    Data Provider Helpers
+
+    Copyright (C) Simo Sorce <ssorce@redhat.com> 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 <netdb.h>
+#include <arpa/inet.h>
+#include "providers/dp_backend.h"
+#include "resolv/async_resolv.h"
+
+struct be_svc_callback {
+    struct be_svc_callback *prev;
+    struct be_svc_callback *next;
+
+    struct be_svc_data *svc;
+
+    be_svc_callback_fn_t *fn;
+    void *private_data;
+};
+
+struct be_svc_data {
+    struct be_svc_data *prev;
+    struct be_svc_data *next;
+
+    const char *name;
+    struct fo_service *fo_service;
+
+    struct hostent *last_good_srvaddr;
+
+    struct be_svc_callback *callbacks;
+};
+
+struct be_failover_ctx {
+    struct fo_ctx *fo_ctx;
+    struct resolv_ctx *resolv;
+
+    struct be_svc_data *svcs;
+};
+
+int be_init_failover(struct be_ctx *ctx)
+{
+    int ret;
+
+    if (ctx->be_fo != NULL) {
+        return EOK;
+    }
+
+    ctx->be_fo = talloc_zero(ctx, struct be_failover_ctx);
+    if (!ctx->be_fo) {
+        return ENOMEM;
+    }
+
+    ret = resolv_init(ctx, ctx->ev, &ctx->be_fo->resolv);
+    if (ret != EOK) {
+        talloc_zfree(ctx->be_fo);
+        return ret;
+    }
+
+    /* todo get timeout from configuration */
+    ctx->be_fo->fo_ctx = fo_context_init(ctx->be_fo, 30);
+    if (!ctx->be_fo->fo_ctx) {
+        talloc_zfree(ctx->be_fo);
+        return ENOMEM;
+    }
+
+    return EOK;
+}
+
+static int be_svc_data_destroy(void *memptr)
+{
+    struct be_svc_data *svc;
+
+    svc = talloc_get_type(memptr, struct be_svc_data);
+
+    while (svc->callbacks) {
+        /* callbacks removes themselves from the list,
+         * so this while will freem them all and then terminate */
+        talloc_free(svc->callbacks);
+    }
+
+    return 0;
+}
+
+int be_fo_add_service(struct be_ctx *ctx, const char *service_name)
+{
+    struct fo_service *service;
+    struct be_svc_data *svc;
+    int ret;
+
+    DLIST_FOR_EACH(svc, ctx->be_fo->svcs) {
+        if (strcmp(svc->name, service_name) == 0) {
+            DEBUG(6, ("Failover service already initialized!\n"));
+            /* we already have a service up and configured,
+             * can happen when using both id and auth provider
+             */
+            return EOK;
+        }
+    }
+
+    /* if not in the be service list, try to create new one */
+
+    ret = fo_new_service(ctx->be_fo->fo_ctx, service_name, &service);
+    if (ret != EOK && ret != EEXIST) {
+        DEBUG(1, ("Failed to create failover service!\n"));
+        return ret;
+    }
+
+    svc = talloc_zero(ctx->be_fo, struct be_svc_data);
+    if (!svc) {
+        return ENOMEM;
+    }
+    talloc_set_destructor((TALLOC_CTX *)svc, be_svc_data_destroy);
+
+    svc->name = talloc_strdup(svc, service_name);
+    if (!svc->name) {
+        talloc_zfree(svc);
+        return ENOMEM;
+    }
+    svc->fo_service = service;
+
+    DLIST_ADD(ctx->be_fo->svcs, svc);
+
+    return EOK;
+}
+
+static int be_svc_callback_destroy(void *memptr)
+{
+    struct be_svc_callback *callback;
+
+    callback = talloc_get_type(memptr, struct be_svc_callback);
+
+    if (callback->svc) {
+        DLIST_REMOVE(callback->svc->callbacks, callback);
+    }
+
+    return 0;
+}
+
+int be_fo_service_add_callback(TALLOC_CTX *memctx,
+                               struct be_ctx *ctx, const char *service_name,
+                               be_svc_callback_fn_t *fn, void *private_data)
+{
+    struct be_svc_callback *callback;
+    struct be_svc_data *svc;
+
+    DLIST_FOR_EACH(svc, ctx->be_fo->svcs) {
+        if (strcmp(svc->name, service_name) == 0) {
+            break;
+        }
+    }
+    if (NULL == svc) {
+        return ENOENT;
+    }
+
+    callback = talloc_zero(memctx, struct be_svc_callback);
+    if (!callback) {
+        return ENOMEM;
+    }
+    talloc_set_destructor((TALLOC_CTX *)callback, be_svc_callback_destroy);
+
+    callback->fn = fn;
+    callback->private_data = private_data;
+
+    DLIST_ADD(svc->callbacks, callback);
+
+    return EOK;
+}
+
+int be_fo_add_server(struct be_ctx *ctx, const char *service_name,
+                     const char *server, int port, void *user_data)
+{
+    struct be_svc_data *svc;
+    int ret;
+
+    DLIST_FOR_EACH(svc, ctx->be_fo->svcs) {
+        if (strcmp(svc->name, service_name) == 0) {
+            break;
+        }
+    }
+    if (NULL == svc) {
+        return ENOENT;
+    }
+
+    ret = fo_add_server(svc->fo_service, server, port, user_data);
+    if (ret && ret != EEXIST) {
+        DEBUG(1, ("Failed to add server to failover service\n"));
+        return ret;
+    }
+
+    return EOK;
+}
+
+struct be_resolve_server_state {
+    struct tevent_context *ev;
+    struct be_ctx *ctx;
+
+    struct be_svc_data *svc;
+    int attempts;
+
+    struct fo_server *srv;
+};
+
+static void be_resolve_server_done(struct tevent_req *subreq);
+
+struct tevent_req *be_resolve_server_send(TALLOC_CTX *memctx,
+                                          struct tevent_context *ev,
+                                          struct be_ctx *ctx,
+                                          const char *service_name)
+{
+    struct tevent_req *req, *subreq;
+    struct be_resolve_server_state *state;
+    struct be_svc_data *svc;
+
+    req = tevent_req_create(memctx, &state, struct be_resolve_server_state);
+    if (!req) return NULL;
+
+    state->ev = ev;
+    state->ctx = ctx;
+
+    DLIST_FOR_EACH(svc, ctx->be_fo->svcs) {
+        if (strcmp(svc->name, service_name) == 0) {
+            state->svc = svc;
+            break;
+        }
+    }
+
+    if (NULL == svc) {
+        tevent_req_error(req, EINVAL);
+        tevent_req_post(req, ev);
+        return req;
+    }
+
+    state->attempts = 0;
+
+    subreq = fo_resolve_service_send(state, ev,
+                                     ctx->be_fo->resolv, svc->fo_service);
+    if (!subreq) {
+        talloc_zfree(req);
+        return NULL;
+    }
+    tevent_req_set_callback(subreq, be_resolve_server_done, req);
+
+    return req;
+}
+
+static void be_resolve_server_done(struct tevent_req *subreq)
+{
+    struct tevent_req *req = tevent_req_callback_data(subreq,
+                                                      struct tevent_req);
+    struct be_resolve_server_state *state = tevent_req_data(req,
+                                             struct be_resolve_server_state);
+    struct be_svc_callback *callback;
+    struct hostent *srvaddr;
+    int ret;
+
+    ret = fo_resolve_service_recv(subreq, &state->srv);
+    talloc_zfree(subreq);
+    switch (ret) {
+    case EOK:
+        if (!state->srv) {
+            tevent_req_error(req, EFAULT);
+            return;
+        }
+        break;
+
+    case ENOENT:
+        /* all servers have been tried and none
+         * was found good, go offline */
+        tevent_req_error(req, EIO);
+        return;
+
+    default:
+        /* mark server as bad and retry */
+        if (!state->srv) {
+            tevent_req_error(req, EFAULT);
+            return;
+        }
+        DEBUG(6, ("Couldn't resolve server (%s), resolver returned (%d)\n",
+                  fo_get_server_name(state->srv), ret));
+
+        /* mark as bad server */
+        fo_set_server_status(state->srv, SERVER_NOT_WORKING);
+
+        state->attempts++;
+        if (state->attempts >= 10) {
+            DEBUG(2, ("Failed to find a server after 10 attempts\n"));
+            tevent_req_error(req, EIO);
+            return;
+        }
+
+        /* now try next one */
+        DEBUG(6, ("Trying with the next one!\n"));
+        subreq = fo_resolve_service_send(state, state->ev,
+                                         state->ctx->be_fo->resolv,
+                                         state->svc->fo_service);
+        if (!subreq) {
+            tevent_req_error(req, ENOMEM);
+            return;
+        }
+        tevent_req_set_callback(subreq, be_resolve_server_done, req);
+
+        return;
+    }
+
+    /* all fine we got the server */
+    srvaddr = fo_get_server_hostent(state->srv);
+
+    if (debug_level >= 4) {
+        char ipaddr[128];
+        inet_ntop(srvaddr->h_addrtype, srvaddr->h_addr_list[0],
+                  ipaddr, 128);
+
+        DEBUG(4, ("Found address for server %s: [%s]\n",
+                  fo_get_server_name(state->srv), ipaddr));
+    }
+
+    /* now call all svc callbacks if server changed */
+    if (srvaddr != state->svc->last_good_srvaddr) {
+        state->svc->last_good_srvaddr = srvaddr;
+
+        DLIST_FOR_EACH(callback, state->svc->callbacks) {
+            callback->fn(callback->private_data, state->srv);
+        }
+    }
+
+    tevent_req_done(req);
+}
+
+int be_resolve_server_recv(struct tevent_req *req, struct fo_server **srv)
+{
+    struct be_resolve_server_state *state = tevent_req_data(req,
+                                             struct be_resolve_server_state);
+
+    TEVENT_REQ_RETURN_ON_ERROR(req);
+
+    if (srv) {
+        *srv = state->srv;
+    }
+
+    return EOK;
+}
+