Refactor dynamic DNS updates

Provides two new layers instead of the previous IPA specific layer:
 1) dp_dyndns.c -- a very generic dyndns layer on the DP level. Its
 purpose it to make it possible for any back end to use dynamic DNS
 updates.
 2) sdap_dyndns.c -- a wrapper around dp_dyndns.c that utilizes some
 LDAP-specific features like autodetecting the address from the LDAP
 connection.

Also converts the dyndns code to new specific error codes.

2 files changed, 545 insertions, 0 deletions

diff --git a/src/providers/ldap/sdap_dyndns.c b/src/providers/ldap/sdap_dyndns.c
new file mode 100644
index 00000000..e7fad7ba
--- /dev/null
+++ b/src/providers/ldap/sdap_dyndns.c
@@ -0,0 +1,498 @@
+/*
+    SSSD
+
+    sdap_dyndns.c: LDAP specific dynamic DNS update
+
+    Authors:
+        Jakub Hrozek <jhrozek@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 "util/util.h"
+#include "resolv/async_resolv.h"
+#include "providers/dp_backend.h"
+#include "providers/dp_dyndns.h"
+#include "providers/ldap/sdap_async_private.h"
+#include "providers/ldap/sdap_id_op.h"
+#include "providers/ldap/ldap_common.h"
+
+static struct tevent_req *
+sdap_dyndns_get_addrs_send(TALLOC_CTX *mem_ctx,
+                           struct tevent_context *ev,
+                           struct sdap_id_ctx *sdap_ctx,
+                           const char *iface);
+static errno_t
+sdap_dyndns_get_addrs_recv(struct tevent_req *req,
+                           TALLOC_CTX *mem_ctx,
+                           struct sss_iface_addr **_addresses);
+
+struct sdap_dyndns_update_state {
+    struct tevent_context *ev;
+    struct be_resolv_ctx *be_res;
+
+    const char *hostname;
+    const char *dns_zone;
+    const char *realm;
+    const char *servername;
+    int ttl;
+
+    struct sss_iface_addr *addresses;
+    uint8_t remove_af;
+
+    bool check_diff;
+    bool use_server_with_nsupdate;
+    char *update_msg;
+};
+
+static void sdap_dyndns_update_addrs_done(struct tevent_req *subreq);
+static void sdap_dyndns_addrs_check_done(struct tevent_req *subreq);
+static errno_t sdap_dyndns_update_step(struct tevent_req *req);
+static void sdap_dyndns_update_done(struct tevent_req *subreq);
+
+struct tevent_req *
+sdap_dyndns_update_send(TALLOC_CTX *mem_ctx,
+                        struct tevent_context *ev,
+                        struct be_ctx *be_ctx,
+                        struct sdap_id_ctx *sdap_ctx,
+                        const char *ifname,
+                        const char *hostname,
+                        const char *dns_zone,
+                        const char *realm,
+                        const char *servername,
+                        const int ttl,
+                        bool check_diff)
+{
+    errno_t ret;
+    struct tevent_req *req;
+    struct tevent_req *subreq;
+    struct sdap_dyndns_update_state *state;
+
+    req = tevent_req_create(mem_ctx, &state, struct sdap_dyndns_update_state);
+    if (req == NULL) {
+        return NULL;
+    }
+    state->check_diff = check_diff;
+    state->hostname = hostname;
+    state->dns_zone = dns_zone;
+    state->realm = realm;
+    state->servername = servername;
+    state->use_server_with_nsupdate = false;
+    state->ttl = ttl;
+    state->be_res = be_ctx->be_res;
+    state->ev = ev;
+
+    if (ifname) {
+       /* Unless one family is restricted, just replace all
+        * address families during the update
+        */
+        switch (state->be_res->family_order) {
+        case IPV4_ONLY:
+            state->remove_af |= DYNDNS_REMOVE_A;
+            break;
+        case IPV6_ONLY:
+            state->remove_af |= DYNDNS_REMOVE_AAAA;
+            break;
+        case IPV4_FIRST:
+        case IPV6_FIRST:
+            state->remove_af |= (DYNDNS_REMOVE_A |
+                                 DYNDNS_REMOVE_AAAA);
+            break;
+        }
+    } else {
+        /* If the interface isn't specified, we ONLY want to have the address
+         * that's connected to the LDAP server stored, so we need to check
+         * (and later remove) both address families.
+         */
+        state->remove_af = (DYNDNS_REMOVE_A | DYNDNS_REMOVE_AAAA);
+    }
+
+    subreq = sdap_dyndns_get_addrs_send(state, state->ev, sdap_ctx, ifname);
+    if (!subreq) {
+        ret = EIO;
+        DEBUG(SSSDBG_OP_FAILURE, ("sdap_id_op_connect_send failed: [%d](%s)\n",
+              ret, sss_strerror(ret)));
+        goto done;
+    }
+    tevent_req_set_callback(subreq, sdap_dyndns_update_addrs_done, req);
+
+    ret = EOK;
+done:
+    if (ret != EOK) {
+        tevent_req_error(req, ret);
+        tevent_req_post(req, ev);
+    }
+    return req;
+}
+
+static void
+sdap_dyndns_update_addrs_done(struct tevent_req *subreq)
+{
+    errno_t ret;
+    struct tevent_req *req;
+    struct sdap_dyndns_update_state *state;
+
+    req = tevent_req_callback_data(subreq, struct tevent_req);
+    state = tevent_req_data(req, struct sdap_dyndns_update_state);
+
+    ret = sdap_dyndns_get_addrs_recv(subreq, state, &state->addresses);
+    if (ret != EOK) {
+        DEBUG(SSSDBG_OP_FAILURE, ("Can't get addresses for DNS update\n"));
+        tevent_req_error(req, ret);
+        return;
+    }
+
+    if (state->check_diff) {
+        /* Check if we need the update at all */
+        subreq = nsupdate_get_addrs_send(state, state->ev,
+                                         state->be_res, state->hostname);
+        if (subreq == NULL) {
+            DEBUG(SSSDBG_OP_FAILURE, ("Can't initiate address check\n"));
+            tevent_req_error(req, ret);
+            return;
+        }
+        tevent_req_set_callback(subreq, sdap_dyndns_addrs_check_done, req);
+        return;
+    }
+
+    /* Perform update */
+    ret = sdap_dyndns_update_step(req);
+    if (ret != EOK) {
+        tevent_req_error(req, ret);
+        return;
+    }
+    /* Execution will resume in sdap_dyndns_update_done */
+}
+
+static void
+sdap_dyndns_addrs_check_done(struct tevent_req *subreq)
+{
+    errno_t ret;
+    int i;
+    struct tevent_req *req;
+    struct sdap_dyndns_update_state *state;
+    char **str_dnslist = NULL, **str_local_list = NULL;
+    char **dns_only = NULL, **local_only = NULL;
+    bool do_update;
+
+    req = tevent_req_callback_data(subreq, struct tevent_req);
+    state = tevent_req_data(req, struct sdap_dyndns_update_state);
+
+    ret = nsupdate_get_addrs_recv(subreq, state, &str_dnslist);
+    talloc_zfree(subreq);
+    if (ret != EOK) {
+        DEBUG(SSSDBG_OP_FAILURE,
+              ("Could not receive list of current addresses [%d]: %s\n",
+              ret, sss_strerror(ret)));
+        tevent_req_error(req, ret);
+        return;
+    }
+
+    ret = sss_iface_addr_list_as_str_list(state,
+                                          state->addresses, &str_local_list);
+    if (ret != EOK) {
+        DEBUG(SSSDBG_OP_FAILURE,
+               ("Converting DNS IP addresses to strings failed: [%d]: %s\n",
+               ret, sss_strerror(ret)));
+        tevent_req_error(req, ret);
+        return;
+    }
+
+    /* Compare the lists */
+    ret = diff_string_lists(state, str_dnslist, str_local_list,
+                            &dns_only, &local_only, NULL);
+    if (ret != EOK) {
+        DEBUG(SSSDBG_OP_FAILURE,
+              ("diff_string_lists failed: [%d]: %s\n", ret, sss_strerror(ret)));
+        tevent_req_error(req, ret);
+        return;
+    }
+
+    if (dns_only) {
+        for (i=0; dns_only[i]; i++) {
+            DEBUG(SSSDBG_TRACE_LIBS,
+                  ("Address in DNS only: %s\n", dns_only[i]));
+            do_update = true;
+        }
+    }
+
+    if (local_only) {
+        for (i=0; local_only[i]; i++) {
+            DEBUG(SSSDBG_TRACE_LIBS,
+                  ("Address on localhost only: %s\n", local_only[i]));
+            do_update = true;
+        }
+    }
+
+    if (do_update) {
+        DEBUG(SSSDBG_TRACE_FUNC,
+              ("Detected IP addresses change, will perform an update\n"));
+        ret = sdap_dyndns_update_step(req);
+        if (ret != EOK) {
+            DEBUG(SSSDBG_OP_FAILURE, ("Could not start the update [%d]: %s\n",
+                  ret, sss_strerror(ret)));
+            tevent_req_error(req, ret);
+        }
+        return;
+    }
+
+    DEBUG(SSSDBG_TRACE_FUNC,
+          ("No DNS update needed, addresses did not change\n"));
+    tevent_req_done(req);
+    return;
+}
+
+static errno_t
+sdap_dyndns_update_step(struct tevent_req *req)
+{
+    errno_t ret;
+    struct sdap_dyndns_update_state *state;
+    const char *servername;
+    struct tevent_req *subreq;
+
+    state = tevent_req_data(req, struct sdap_dyndns_update_state);
+
+    servername = NULL;
+    if (state->use_server_with_nsupdate == true &&
+        state->servername) {
+        servername = state->servername;
+    }
+
+    ret = be_nsupdate_create_msg(state, state->realm, state->dns_zone,
+                                 servername, state->hostname,
+                                 state->ttl, state->remove_af,
+                                 state->addresses,
+                                 &state->update_msg);
+    if (ret != EOK) {
+        DEBUG(SSSDBG_OP_FAILURE, ("Can't get addresses for DNS update\n"));
+        return ret;
+    }
+
+    /* Fork a child process to perform the DNS update */
+    subreq = be_nsupdate_send(state, state->ev, state->update_msg);
+    if (subreq == NULL) {
+        return EIO;
+    }
+
+    tevent_req_set_callback(subreq, sdap_dyndns_update_done, req);
+    return EOK;
+}
+
+static void
+sdap_dyndns_update_done(struct tevent_req *subreq)
+{
+    errno_t ret;
+    int child_status;
+    struct tevent_req *req;
+    struct sdap_dyndns_update_state *state;
+
+    req = tevent_req_callback_data(subreq, struct tevent_req);
+    state = tevent_req_data(req, struct sdap_dyndns_update_state);
+
+    ret = be_nsupdate_recv(subreq, &child_status);
+    talloc_zfree(subreq);
+    if (ret != EOK) {
+        /* If the update didn't succeed, we can retry using the server name */
+        if (state->use_server_with_nsupdate == false && state->servername &&
+            WIFEXITED(child_status) && WEXITSTATUS(child_status) != 0) {
+            state->use_server_with_nsupdate = true;
+            DEBUG(SSSDBG_MINOR_FAILURE,
+                   ("nsupdate failed, retrying with server name\n"));
+            ret = sdap_dyndns_update_step(req);
+            if (ret == EOK) {
+                return;
+            }
+        }
+
+        tevent_req_error(req, ret);
+        return;
+    }
+
+    tevent_req_done(req);
+}
+
+errno_t
+sdap_dyndns_update_recv(struct tevent_req *req)
+{
+    TEVENT_REQ_RETURN_ON_ERROR(req);
+    return EOK;
+}
+
+/* A request to get addresses to update with */
+struct sdap_dyndns_get_addrs_state {
+    struct sdap_id_op* sdap_op;
+    struct sss_iface_addr *addresses;
+};
+
+static void sdap_dyndns_get_addrs_done(struct tevent_req *subreq);
+static errno_t sdap_dyndns_add_ldap_conn(struct sdap_dyndns_get_addrs_state *state,
+                                         struct sdap_handle *sh);
+
+static struct tevent_req *
+sdap_dyndns_get_addrs_send(TALLOC_CTX *mem_ctx,
+                           struct tevent_context *ev,
+                           struct sdap_id_ctx *sdap_ctx,
+                           const char *iface)
+{
+    errno_t ret;
+    struct tevent_req *req;
+    struct tevent_req *subreq;
+    struct sdap_dyndns_get_addrs_state *state;
+
+    req = tevent_req_create(mem_ctx, &state,
+                            struct sdap_dyndns_get_addrs_state);
+    if (req == NULL) {
+        return NULL;
+    }
+
+    if (iface) {
+        ret = sss_iface_addr_list_get(state, iface, &state->addresses);
+        if (ret != EOK) {
+            DEBUG(SSSDBG_OP_FAILURE,
+                  ("Cannot get list of addresses from interface %s\n", iface));
+        }
+        /* We're done. Just fake an async request completion */
+        goto done;
+    }
+
+    /* Detect DYNDNS address from LDAP connection */
+    state->sdap_op = sdap_id_op_create(state, sdap_ctx->conn_cache);
+    if (!state->sdap_op) {
+        ret = ENOMEM;
+        DEBUG(SSSDBG_OP_FAILURE, ("sdap_id_op_create failed\n"));
+        goto done;
+    }
+
+    subreq = sdap_id_op_connect_send(state->sdap_op, state, &ret);
+    if (!subreq) {
+        ret = EIO;
+        DEBUG(SSSDBG_OP_FAILURE, ("sdap_id_op_connect_send failed: [%d](%s)\n",
+              ret, sss_strerror(ret)));
+        goto done;
+    }
+    tevent_req_set_callback(subreq, sdap_dyndns_get_addrs_done, req);
+
+    ret = EAGAIN;
+done:
+    if (ret == EOK) {
+        tevent_req_done(req);
+        tevent_req_post(req, ev);
+    } else if (ret != EAGAIN) {
+        tevent_req_error(req, ret);
+        tevent_req_post(req, ev);
+    }
+
+    /* EAGAIN - resolution in progress */
+    return req;
+}
+
+static void
+sdap_dyndns_get_addrs_done(struct tevent_req *subreq)
+{
+    errno_t ret;
+    int dp_error;
+    struct tevent_req *req;
+    struct sdap_dyndns_get_addrs_state *state;
+
+    req = tevent_req_callback_data(subreq, struct tevent_req);
+    state = tevent_req_data(req, struct sdap_dyndns_get_addrs_state);
+
+    ret = sdap_id_op_connect_recv(subreq, &dp_error);
+    talloc_zfree(subreq);
+    if (ret != EOK) {
+        if (dp_error == DP_ERR_OFFLINE) {
+            DEBUG(SSSDBG_MINOR_FAILURE, ("No LDAP server is available, "
+                  "dynamic DNS update is skipped in offline mode.\n"));
+            ret = ERR_DYNDNS_OFFLINE;
+        } else {
+            DEBUG(SSSDBG_OP_FAILURE,
+                  ("Failed to connect to LDAP server: [%d](%s)\n",
+                  ret, sss_strerror(ret)));
+        }
+        tevent_req_error(req, ret);
+        return;
+    }
+
+    ret = sdap_dyndns_add_ldap_conn(state, sdap_id_op_handle(state->sdap_op));
+    if (ret != EOK) {
+        DEBUG(SSSDBG_OP_FAILURE, ("Can't get addresses from LDAP connection\n"));
+        tevent_req_error(req, ret);
+        return;
+    }
+
+    /* Got the address! Done! */
+    tevent_req_done(req);
+}
+
+static errno_t
+sdap_dyndns_add_ldap_conn(struct sdap_dyndns_get_addrs_state *state,
+                          struct sdap_handle *sh)
+{
+    int ret;
+    int fd;
+    struct sss_iface_addr *address;
+    struct sockaddr_storage ss;
+    socklen_t ss_len = sizeof(ss);
+
+    if (sh == NULL) {
+        return EINVAL;
+    }
+
+    /* Get the file descriptor for the primary LDAP connection */
+    ret = get_fd_from_ldap(sh->ldap, &fd);
+    if (ret != EOK) {
+        return ret;
+    }
+
+    errno = 0;
+    ret = getsockname(fd, (struct sockaddr *) &ss, &ss_len);
+    if (ret == -1) {
+        ret = errno;
+        DEBUG(SSSDBG_CRIT_FAILURE, ("Failed to get socket name\n"));
+        return ret;
+    }
+
+    switch(ss.ss_family) {
+    case AF_INET:
+    case AF_INET6:
+        address = sss_iface_addr_add(state, &state->addresses, &ss);
+        if (address == NULL) {
+            return ENOMEM;
+        }
+        break;
+    default:
+        DEBUG(SSSDBG_CRIT_FAILURE,
+              ("Connection to LDAP is neither IPv4 nor IPv6\n"));
+        return EIO;
+    }
+
+    return EOK;
+}
+
+static errno_t
+sdap_dyndns_get_addrs_recv(struct tevent_req *req,
+                           TALLOC_CTX *mem_ctx,
+                           struct sss_iface_addr **_addresses)
+{
+    struct sdap_dyndns_get_addrs_state *state;
+
+    state = tevent_req_data(req, struct sdap_dyndns_get_addrs_state);
+
+    TEVENT_REQ_RETURN_ON_ERROR(req);
+
+    *_addresses = talloc_steal(mem_ctx, state->addresses);
+    return EOK;
+}
diff --git a/src/providers/ldap/sdap_dyndns.h b/src/providers/ldap/sdap_dyndns.h
new file mode 100644
index 00000000..1602938e
--- /dev/null
+++ b/src/providers/ldap/sdap_dyndns.h
@@ -0,0 +1,47 @@
+/*
+    SSSD
+
+    sdap_dyndns.h: LDAP specific dynamic DNS update
+
+    Authors:
+        Jakub Hrozek <jhrozek@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/>.
+*/
+
+#ifndef SDAP_DYNDNS_H_
+#define SDAP_DYNDNS_H_
+
+#include "util/util.h"
+#include "providers/dp_backend.h"
+#include "providers/ldap/ldap_common.h"
+
+struct tevent_req *
+sdap_dyndns_update_send(TALLOC_CTX *mem_ctx,
+                        struct tevent_context *ev,
+                        struct be_ctx *be_ctx,
+                        struct sdap_id_ctx *sdap_ctx,
+                        const char *ifname,
+                        const char *hostname,
+                        const char *dns_zone,
+                        const char *realm,
+                        const char *servername,
+                        const int ttl,
+                        bool check_diff);
+
+errno_t sdap_dyndns_update_recv(struct tevent_req *req);
+
+#endif /* SDAP_DYNDNS_H_ */