fail_over_srv.c revision a3c8390d19593b1e5277d95bfb4ab206d4785150
/*
Authors:
Pavel Březina <pbrezina@redhat.com>
Copyright (C) 2013 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 <strings.h>
#include <talloc.h>
#include <tevent.h>
#include "util/util.h"
#include "resolv/async_resolv.h"
#include "providers/fail_over_srv.h"
struct fo_discover_srv_state {
char *dns_domain;
struct fo_server_info *servers;
size_t num_servers;
};
static void fo_discover_srv_done(struct tevent_req *subreq);
struct tevent_req *fo_discover_srv_send(TALLOC_CTX *mem_ctx,
struct tevent_context *ev,
struct resolv_ctx *resolv_ctx,
const char *service,
const char *protocol,
const char **discovery_domains)
{
struct fo_discover_srv_state *state = NULL;
struct tevent_req *req = NULL;
struct tevent_req *subreq = NULL;
errno_t ret;
req = tevent_req_create(mem_ctx, &state, struct fo_discover_srv_state);
if (req == NULL) {
DEBUG(SSSDBG_CRIT_FAILURE, "tevent_req_create() failed\n");
return NULL;
}
subreq = resolv_discover_srv_send(state, ev, resolv_ctx, service,
protocol, discovery_domains);
if (subreq == NULL) {
ret = ENOMEM;
goto immediately;
}
tevent_req_set_callback(subreq, fo_discover_srv_done, req);
return req;
immediately:
tevent_req_error(req, ret);
tevent_req_post(req, ev);
return req;
}
static void fo_discover_srv_done(struct tevent_req *subreq)
{
struct fo_discover_srv_state *state = NULL;
struct tevent_req *req = NULL;
struct ares_srv_reply *reply_list = NULL;
struct ares_srv_reply *record = NULL;
int i;
errno_t ret;
req = tevent_req_callback_data(subreq, struct tevent_req);
state = tevent_req_data(req, struct fo_discover_srv_state);
ret = resolv_discover_srv_recv(state, subreq,
&reply_list, &state->dns_domain);
talloc_zfree(subreq);
if (ret == ENOENT) {
ret = ERR_SRV_NOT_FOUND;
goto done;
} else if (ret == EIO) {
ret = ERR_SRV_LOOKUP_ERROR;
goto done;
} else if (ret != EOK) {
goto done;
}
DEBUG(SSSDBG_TRACE_FUNC, "Got answer. Processing...\n");
/* sort and store the answer */
ret = resolv_sort_srv_reply(&reply_list);
if (ret != EOK) {
DEBUG(SSSDBG_CRIT_FAILURE, "Could not sort the answers from DNS "
"[%d]: %s\n", ret, strerror(ret));
goto done;
}
state->num_servers = 0;
for (record = reply_list; record != NULL; record = record->next) {
state->num_servers++;
}
DEBUG(SSSDBG_TRACE_FUNC, "Got %zu servers\n", state->num_servers);
state->servers = talloc_array(state, struct fo_server_info,
state->num_servers);
if (state->servers == NULL) {
ret = ENOMEM;
goto done;
}
for (record = reply_list, i = 0;
record != NULL;
record = record->next, i++) {
state->servers[i].host = talloc_steal(state->servers, record->host);
state->servers[i].port = record->port;
state->servers[i].priority = record->priority;
}
talloc_zfree(reply_list);
ret = EOK;
done:
if (ret != EOK) {
tevent_req_error(req, ret);
return;
}
tevent_req_done(req);
}
errno_t fo_discover_srv_recv(TALLOC_CTX *mem_ctx,
struct tevent_req *req,
char **_dns_domain,
struct fo_server_info **_servers,
size_t *_num_servers)
{
struct fo_discover_srv_state *state = NULL;
state = tevent_req_data(req, struct fo_discover_srv_state);
TEVENT_REQ_RETURN_ON_ERROR(req);
if (_dns_domain != NULL) {
*_dns_domain = talloc_steal(mem_ctx, state->dns_domain);
}
if (_servers != NULL) {
*_servers = talloc_steal(mem_ctx, state->servers);
}
if (_num_servers != NULL) {
*_num_servers = state->num_servers;
}
return EOK;
}
struct fo_discover_servers_state {
struct tevent_context *ev;
struct resolv_ctx *resolv_ctx;
const char *service;
const char *protocol;
const char *primary_domain;
const char *backup_domain;
char *dns_domain;
struct fo_server_info *primary_servers;
size_t num_primary_servers;
struct fo_server_info *backup_servers;
size_t num_backup_servers;
};
static void fo_discover_servers_primary_done(struct tevent_req *subreq);
static void fo_discover_servers_backup_done(struct tevent_req *subreq);
struct tevent_req *fo_discover_servers_send(TALLOC_CTX *mem_ctx,
struct tevent_context *ev,
struct resolv_ctx *resolv_ctx,
const char *service,
const char *protocol,
const char *primary_domain,
const char *backup_domain)
{
struct fo_discover_servers_state *state = NULL;
struct tevent_req *req = NULL;
struct tevent_req *subreq = NULL;
const char **domains = NULL;
errno_t ret;
req = tevent_req_create(mem_ctx, &state,
struct fo_discover_servers_state);
if (req == NULL) {
DEBUG(SSSDBG_CRIT_FAILURE, "tevent_req_create() failed\n");
return NULL;
}
if (primary_domain == NULL) {
if (backup_domain == NULL) {
state->primary_servers = NULL;
state->num_primary_servers = 0;
state->backup_servers = NULL;
state->num_backup_servers = 0;
state->dns_domain = NULL;
ret = EOK;
goto immediately;
} else {
primary_domain = backup_domain;
backup_domain = NULL;
}
}
state->ev = ev;
state->resolv_ctx = resolv_ctx;
state->service = talloc_strdup(state, service);
if (state->service == NULL) {
ret = ENOMEM;
goto immediately;
}
state->protocol = talloc_strdup(state, protocol);
if (state->protocol == NULL) {
ret = ENOMEM;
goto immediately;
}
state->primary_domain = talloc_strdup(state, primary_domain);
if (state->primary_domain == NULL) {
ret = ENOMEM;
goto immediately;
}
state->backup_domain = talloc_strdup(state, backup_domain);
if (state->backup_domain == NULL && backup_domain != NULL) {
ret = ENOMEM;
goto immediately;
}
DEBUG(SSSDBG_TRACE_FUNC, "Looking up primary servers\n");
domains = talloc_zero_array(state, const char *, 3);
if (domains == NULL) {
ret = ENOMEM;
goto immediately;
}
domains[0] = state->primary_domain;
domains[1] = state->backup_domain;
subreq = fo_discover_srv_send(state, ev, resolv_ctx,
state->service, state->protocol, domains);
if (subreq == NULL) {
ret = ENOMEM;
goto immediately;
}
tevent_req_set_callback(subreq, fo_discover_servers_primary_done, req);
return req;
immediately:
tevent_req_error(req, ret);
tevent_req_post(req, ev);
return req;
}
static void fo_discover_servers_primary_done(struct tevent_req *subreq)
{
struct fo_discover_servers_state *state = NULL;
struct tevent_req *req = NULL;
const char **domains = NULL;
errno_t ret;
req = tevent_req_callback_data(subreq, struct tevent_req);
state = tevent_req_data(req, struct fo_discover_servers_state);
ret = fo_discover_srv_recv(state, subreq,
&state->dns_domain,
&state->primary_servers,
&state->num_primary_servers);
talloc_zfree(subreq);
if (ret != EOK) {
DEBUG(SSSDBG_OP_FAILURE, "Unable to retrieve primary servers "
"[%d]: %s\n", ret, sss_strerror(ret));
if (ret != ERR_SRV_NOT_FOUND && ret != ERR_SRV_LOOKUP_ERROR) {
/* abort on system error */
goto done;
}
}
if (state->backup_domain == NULL) {
/* if there is no backup domain, we are done */
DEBUG(SSSDBG_TRACE_FUNC, "No backup domain specified\n");
goto done;
}
if (state->dns_domain != NULL
&& strcasecmp(state->dns_domain, state->backup_domain) == 0) {
/* If there was no error and dns_domain is the same as backup domain,
* it means that we were unable to resolve SRV in primary domain, but
* SRV from backup domain was resolved and those servers are considered
* to be primary. We are done. */
state->backup_servers = NULL;
state->num_backup_servers = 0;
ret = EOK;
goto done;
}
DEBUG(SSSDBG_TRACE_FUNC, "Looking up backup servers\n");
domains = talloc_zero_array(state, const char *, 2);
if (domains == NULL) {
ret = ENOMEM;
goto done;
}
domains[0] = state->backup_domain;
subreq = fo_discover_srv_send(state, state->ev, state->resolv_ctx,
state->service, state->protocol, domains);
if (subreq == NULL) {
ret = ENOMEM;
goto done;
}
tevent_req_set_callback(subreq, fo_discover_servers_backup_done, req);
ret = EAGAIN;
done:
if (ret == EOK) {
tevent_req_done(req);
} else if (ret != EAGAIN) {
tevent_req_error(req, ret);
}
return;
}
static void fo_discover_servers_backup_done(struct tevent_req *subreq)
{
struct fo_discover_servers_state *state = NULL;
struct tevent_req *req = NULL;
errno_t ret;
req = tevent_req_callback_data(subreq, struct tevent_req);
state = tevent_req_data(req, struct fo_discover_servers_state);
ret = fo_discover_srv_recv(state, subreq, NULL,
&state->backup_servers,
&state->num_backup_servers);
talloc_zfree(subreq);
if (ret != EOK) {
DEBUG(SSSDBG_MINOR_FAILURE, "Unable to retrieve backup servers "
"[%d]: %s\n", ret, sss_strerror(ret));
if (ret == ERR_SRV_NOT_FOUND || ret == ERR_SRV_LOOKUP_ERROR) {
/* we have successfully fetched primary servers, so we will
* finish the request normally on non system error */
ret = EOK;
}
}
if (ret != EOK) {
tevent_req_error(req, ret);
return;
}
tevent_req_done(req);
}
errno_t fo_discover_servers_recv(TALLOC_CTX *mem_ctx,
struct tevent_req *req,
char **_dns_domain,
struct fo_server_info **_primary_servers,
size_t *_num_primary_servers,
struct fo_server_info **_backup_servers,
size_t *_num_backup_servers)
{
struct fo_discover_servers_state *state = NULL;
state = tevent_req_data(req, struct fo_discover_servers_state);
TEVENT_REQ_RETURN_ON_ERROR(req);
if (_primary_servers) {
*_primary_servers = talloc_steal(mem_ctx, state->primary_servers);
}
if (_num_primary_servers) {
*_num_primary_servers = state->num_primary_servers;
}
if (_backup_servers) {
*_backup_servers = talloc_steal(mem_ctx, state->backup_servers);
}
if (_num_backup_servers) {
*_num_backup_servers = state->num_backup_servers;
}
if (_dns_domain) {
*_dns_domain = talloc_steal(mem_ctx, state->dns_domain);
}
return EOK;
}
struct fo_resolve_srv_dns_ctx {
struct resolv_ctx *resolv_ctx;
enum restrict_family family_order;
enum host_database *host_dbs;
char *hostname;
char *sssd_domain;
char *detected_domain;
};
struct fo_resolve_srv_dns_state {
struct tevent_context *ev;
struct fo_resolve_srv_dns_ctx *ctx;
const char *service;
const char *protocol;
const char *discovery_domain;
char *dns_domain;
struct fo_server_info *servers;
size_t num_servers;
};
static void fo_resolve_srv_dns_domain_done(struct tevent_req *subreq);
static errno_t fo_resolve_srv_dns_discover(struct tevent_req *req);
static void fo_resolve_srv_dns_done(struct tevent_req *subreq);
struct fo_resolve_srv_dns_ctx *
fo_resolve_srv_dns_ctx_init(TALLOC_CTX *mem_ctx,
struct resolv_ctx *resolv_ctx,
enum restrict_family family_order,
enum host_database *host_dbs,
const char *hostname,
const char *sssd_domain)
{
struct fo_resolve_srv_dns_ctx *ctx = NULL;
ctx = talloc_zero(mem_ctx, struct fo_resolve_srv_dns_ctx);
if (ctx == NULL) {
return NULL;
}
ctx->resolv_ctx = resolv_ctx;
ctx->family_order = family_order;
ctx->host_dbs = host_dbs;
ctx->hostname = talloc_strdup(ctx, hostname);
if (ctx->hostname == NULL) {
goto fail;
}
ctx->sssd_domain = talloc_strdup(ctx, sssd_domain);
if (ctx->sssd_domain == NULL) {
goto fail;
}
return ctx;
fail:
talloc_free(ctx);
return NULL;
}
struct tevent_req *fo_resolve_srv_dns_send(TALLOC_CTX *mem_ctx,
struct tevent_context *ev,
const char *service,
const char *protocol,
const char *discovery_domain,
void *pvt)
{
struct fo_resolve_srv_dns_state *state = NULL;
struct fo_resolve_srv_dns_ctx *ctx = NULL;
struct tevent_req *req = NULL;
struct tevent_req *subreq = NULL;
errno_t ret;
req = tevent_req_create(mem_ctx, &state, struct fo_resolve_srv_dns_state);
if (req == NULL) {
DEBUG(SSSDBG_CRIT_FAILURE, "tevent_req_create() failed\n");
return NULL;
}
ctx = talloc_get_type(pvt, struct fo_resolve_srv_dns_ctx);
if (ctx == NULL) {
ret = EINVAL;
goto immediately;
}
state->ev = ev;
state->ctx = ctx;
state->service = service;
state->protocol = protocol;
if (discovery_domain == NULL) {
state->discovery_domain = NULL;
} else {
state->discovery_domain = discovery_domain;
}
if (discovery_domain == NULL && ctx->detected_domain == NULL) {
/* we will try to detect proper discovery domain */
subreq = resolv_get_domain_send(state, state->ev, ctx->resolv_ctx,
ctx->hostname, ctx->host_dbs,
ctx->family_order);
if (subreq == NULL) {
ret = ENOMEM;
goto immediately;
}
tevent_req_set_callback(subreq, fo_resolve_srv_dns_domain_done, req);
} else {
/* we will use either provided or previously detected
* discovery domain */
ret = fo_resolve_srv_dns_discover(req);
if (ret != EAGAIN) {
goto immediately;
}
}
return req;
immediately:
if (ret == EOK) {
tevent_req_done(req);
} else {
tevent_req_error(req, ret);
}
tevent_req_post(req, ev);
return req;
}
static void fo_resolve_srv_dns_domain_done(struct tevent_req *subreq)
{
struct fo_resolve_srv_dns_state *state = NULL;
struct tevent_req *req = NULL;
errno_t ret;
req = tevent_req_callback_data(subreq, struct tevent_req);
state = tevent_req_data(req, struct fo_resolve_srv_dns_state);
ret = resolv_get_domain_recv(state->ctx, subreq,
&state->ctx->detected_domain);
talloc_zfree(subreq);
if (ret != EOK) {
goto done;
}
ret = fo_resolve_srv_dns_discover(req);
done:
if (ret == EOK) {
tevent_req_done(req);
} else if (ret != EAGAIN) {
tevent_req_error(req, ret);
}
return;
}
static errno_t fo_resolve_srv_dns_discover(struct tevent_req *req)
{
struct fo_resolve_srv_dns_state *state = NULL;
struct fo_resolve_srv_dns_ctx *ctx = NULL;
struct tevent_req *subreq = NULL;
const char **domains = NULL;
errno_t ret;
state = tevent_req_data(req, struct fo_resolve_srv_dns_state);
ctx = state->ctx;
domains = talloc_zero_array(state, const char *, 3);
if (domains == NULL) {
ret = ENOMEM;
goto done;
}
if (state->discovery_domain == NULL) {
/* we will use detected domain with SSSD domain as fallback */
domains[0] = talloc_strdup(domains, ctx->detected_domain);
if (domains[0] == NULL) {
ret = ENOMEM;
goto done;
}
if (strcasecmp(ctx->detected_domain, ctx->sssd_domain) != 0) {
domains[1] = talloc_strdup(domains, ctx->sssd_domain);
if (domains[1] == NULL) {
ret = ENOMEM;
goto done;
}
}
} else {
/* We will use only discovery domain that was provided via plugin
* interface. We don't have to dup here because it is already on
* state. */
domains[0] = state->discovery_domain;
}
subreq = fo_discover_srv_send(state, state->ev, ctx->resolv_ctx,
state->service, state->protocol, domains);
if (subreq == NULL) {
ret = ENOMEM;
goto done;
}
tevent_req_set_callback(subreq, fo_resolve_srv_dns_done, req);
ret = EAGAIN;
done:
if (ret != EAGAIN) {
talloc_free(domains);
}
return ret;
}
static void fo_resolve_srv_dns_done(struct tevent_req *subreq)
{
struct fo_resolve_srv_dns_state *state = NULL;
struct tevent_req *req = NULL;
errno_t ret;
req = tevent_req_callback_data(subreq, struct tevent_req);
state = tevent_req_data(req, struct fo_resolve_srv_dns_state);
ret = fo_discover_srv_recv(state, subreq, &state->dns_domain,
&state->servers, &state->num_servers);
talloc_zfree(subreq);
if (ret != EOK) {
goto done;
}
done:
if (ret != EOK) {
tevent_req_error(req, ret);
return;
}
tevent_req_done(req);
}
errno_t fo_resolve_srv_dns_recv(TALLOC_CTX *mem_ctx,
struct tevent_req *req,
char **_dns_domain,
struct fo_server_info **_primary_servers,
size_t *_num_primary_servers,
struct fo_server_info **_backup_servers,
size_t *_num_backup_servers)
{
struct fo_resolve_srv_dns_state *state = NULL;
state = tevent_req_data(req, struct fo_resolve_srv_dns_state);
TEVENT_REQ_RETURN_ON_ERROR(req);
if (_primary_servers) {
*_primary_servers = talloc_steal(mem_ctx, state->servers);
}
if (_num_primary_servers) {
*_num_primary_servers = state->num_servers;
}
/* backup servers are not supported by simple srv lookup */
if (_backup_servers) {
*_backup_servers = NULL;
}
if (_num_backup_servers) {
*_num_backup_servers = 0;
}
if (_dns_domain) {
*_dns_domain = talloc_steal(mem_ctx, state->dns_domain);
}
return EOK;
}