source: trunk/server/source3/lib/serverid.c

/*
   Unix SMB/CIFS implementation.
   Implementation of a reliable server_exists()
   Copyright (C) Volker Lendecke 2010

   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 "includes.h"
#include "system/filesys.h"
#include "serverid.h"
#include "util_tdb.h"
#include "dbwrap.h"
#include "lib/util/tdb_wrap.h"

struct serverid_key {
        pid_t pid;
        uint32_t vnn;
};

struct serverid_data {
        uint64_t unique_id;
        uint32_t msg_flags;
};

static struct db_context *db_ptr = NULL;

static struct db_context *serverid_init(TALLOC_CTX *mem_ctx,
                                        bool readonly)
{
        db_ptr = db_open(mem_ctx, lock_path("serverid.tdb"),
                         0, TDB_DEFAULT|TDB_CLEAR_IF_FIRST|TDB_INCOMPATIBLE_HASH,
                         readonly ? O_RDONLY : O_RDWR | O_CREAT,
                         0644);
        return db_ptr;
}

bool serverid_parent_init(TALLOC_CTX *mem_ctx)
{
        /*
         * Open the tdb in the parent process (smbd) so that our
         * CLEAR_IF_FIRST optimization in tdb_reopen_all can properly
         * work.
         */

        if (serverid_init(mem_ctx, false) == NULL) {
                DEBUG(1, ("could not open serverid.tdb: %s\n",
                          strerror(errno)));
                return false;
        }

        return true;
}

bool serverid_init_readonly(TALLOC_CTX *mem_ctx)
{
        if (serverid_init(mem_ctx, true) == NULL) {
                DEBUG(1, ("could not open serverid.tdb: %s\n",
                          strerror(errno)));
                return false;
        }

        return true;
}

static struct db_context *serverid_db(void)
{
        if (db_ptr != NULL) {
                return db_ptr;
        }

        return serverid_init(NULL, false);
}

static void serverid_fill_key(const struct server_id *id,
                              struct serverid_key *key)
{
        ZERO_STRUCTP(key);
        key->pid = id->pid;
        key->vnn = id->vnn;
}

bool serverid_register(const struct server_id id, uint32_t msg_flags)
{
        struct db_context *db;
        struct serverid_key key;
        struct serverid_data data;
        struct db_record *rec;
        TDB_DATA tdbkey, tdbdata;
        NTSTATUS status;
        bool ret = false;

        db = serverid_db();
        if (db == NULL) {
                return false;
        }

        serverid_fill_key(&id, &key);
        tdbkey = make_tdb_data((uint8_t *)&key, sizeof(key));

        rec = db->fetch_locked(db, talloc_tos(), tdbkey);
        if (rec == NULL) {
                DEBUG(1, ("Could not fetch_lock serverid.tdb record\n"));
                return false;
        }

        ZERO_STRUCT(data);
        data.unique_id = id.unique_id;
        data.msg_flags = msg_flags;

        tdbdata = make_tdb_data((uint8_t *)&data, sizeof(data));
        status = rec->store(rec, tdbdata, 0);
        if (!NT_STATUS_IS_OK(status)) {
                DEBUG(1, ("Storing serverid.tdb record failed: %s\n",
                          nt_errstr(status)));
                goto done;
        }
        ret = true;
done:
        TALLOC_FREE(rec);
        return ret;
}

bool serverid_register_msg_flags(const struct server_id id, bool do_reg,
                                 uint32_t msg_flags)
{
        struct db_context *db;
        struct serverid_key key;
        struct serverid_data *data;
        struct db_record *rec;
        TDB_DATA tdbkey;
        NTSTATUS status;
        bool ret = false;

        db = serverid_db();
        if (db == NULL) {
                return false;
        }

        serverid_fill_key(&id, &key);
        tdbkey = make_tdb_data((uint8_t *)&key, sizeof(key));

        rec = db->fetch_locked(db, talloc_tos(), tdbkey);
        if (rec == NULL) {
                DEBUG(1, ("Could not fetch_lock serverid.tdb record\n"));
                return false;
        }

        if (rec->value.dsize != sizeof(struct serverid_data)) {
                DEBUG(1, ("serverid record has unexpected size %d "
                          "(wanted %d)\n", (int)rec->value.dsize,
                          (int)sizeof(struct serverid_data)));
                goto done;
        }

        data = (struct serverid_data *)rec->value.dptr;

        if (do_reg) {
                data->msg_flags |= msg_flags;
        } else {
                data->msg_flags &= ~msg_flags;
        }

        status = rec->store(rec, rec->value, 0);
        if (!NT_STATUS_IS_OK(status)) {
                DEBUG(1, ("Storing serverid.tdb record failed: %s\n",
                          nt_errstr(status)));
                goto done;
        }
        ret = true;
done:
        TALLOC_FREE(rec);
        return ret;
}

bool serverid_deregister(struct server_id id)
{
        struct db_context *db;
        struct serverid_key key;
        struct db_record *rec;
        TDB_DATA tdbkey;
        NTSTATUS status;
        bool ret = false;

        db = serverid_db();
        if (db == NULL) {
                return false;
        }

        serverid_fill_key(&id, &key);
        tdbkey = make_tdb_data((uint8_t *)&key, sizeof(key));

        rec = db->fetch_locked(db, talloc_tos(), tdbkey);
        if (rec == NULL) {
                DEBUG(1, ("Could not fetch_lock serverid.tdb record\n"));
                return false;
        }

        status = rec->delete_rec(rec);
        if (!NT_STATUS_IS_OK(status)) {
                DEBUG(1, ("Deleting serverid.tdb record failed: %s\n",
                          nt_errstr(status)));
                goto done;
        }
        ret = true;
done:
        TALLOC_FREE(rec);
        return ret;
}

struct serverid_exists_state {
        const struct server_id *id;
        bool exists;
};

static int server_exists_parse(TDB_DATA key, TDB_DATA data, void *priv)
{
        struct serverid_exists_state *state =
                (struct serverid_exists_state *)priv;

        if (data.dsize != sizeof(struct serverid_data)) {
                return -1;
        }

        /*
         * Use memcmp, not direct compare. data.dptr might not be
         * aligned.
         */
        state->exists = (memcmp(&state->id->unique_id, data.dptr,
                                sizeof(state->id->unique_id)) == 0);
        return 0;
}

bool serverid_exists(const struct server_id *id)
{
        struct db_context *db;
        struct serverid_exists_state state;
        struct serverid_key key;
        TDB_DATA tdbkey;

        if (procid_is_me(id)) {
                return true;
        }

        if (!process_exists(*id)) {
                return false;
        }

        if (id->unique_id == SERVERID_UNIQUE_ID_NOT_TO_VERIFY) {
                return true;
        }

        db = serverid_db();
        if (db == NULL) {
                return false;
        }

        serverid_fill_key(id, &key);
        tdbkey = make_tdb_data((uint8_t *)&key, sizeof(key));

        state.id = id;
        state.exists = false;

        if (db->parse_record(db, tdbkey, server_exists_parse, &state) == -1) {
                return false;
        }
        return state.exists;
}

static bool serverid_rec_parse(const struct db_record *rec,
                               struct server_id *id, uint32_t *msg_flags)
{
        struct serverid_key key;
        struct serverid_data data;

        if (rec->key.dsize != sizeof(key)) {
                DEBUG(1, ("Found invalid key length %d in serverid.tdb\n",
                          (int)rec->key.dsize));
                return false;
        }
        if (rec->value.dsize != sizeof(data)) {
                DEBUG(1, ("Found invalid value length %d in serverid.tdb\n",
                          (int)rec->value.dsize));
                return false;
        }

        memcpy(&key, rec->key.dptr, sizeof(key));
        memcpy(&data, rec->value.dptr, sizeof(data));

        id->pid = key.pid;
        id->vnn = key.vnn;
        id->unique_id = data.unique_id;
        *msg_flags = data.msg_flags;
        return true;
}

struct serverid_traverse_read_state {
        int (*fn)(const struct server_id *id, uint32_t msg_flags,
                  void *private_data);
        void *private_data;
};

static int serverid_traverse_read_fn(struct db_record *rec, void *private_data)
{
        struct serverid_traverse_read_state *state =
                (struct serverid_traverse_read_state *)private_data;
        struct server_id id;
        uint32_t msg_flags;

        if (!serverid_rec_parse(rec, &id, &msg_flags)) {
                return 0;
        }
        return state->fn(&id, msg_flags,state->private_data);
}

bool serverid_traverse_read(int (*fn)(const struct server_id *id,
                                      uint32_t msg_flags, void *private_data),
                            void *private_data)
{
        struct db_context *db;
        struct serverid_traverse_read_state state;

        db = serverid_db();
        if (db == NULL) {
                return false;
        }
        state.fn = fn;
        state.private_data = private_data;
        return db->traverse_read(db, serverid_traverse_read_fn, &state);
}

struct serverid_traverse_state {
        int (*fn)(struct db_record *rec, const struct server_id *id,
                  uint32_t msg_flags, void *private_data);
        void *private_data;
};

static int serverid_traverse_fn(struct db_record *rec, void *private_data)
{
        struct serverid_traverse_state *state =
                (struct serverid_traverse_state *)private_data;
        struct server_id id;
        uint32_t msg_flags;

        if (!serverid_rec_parse(rec, &id, &msg_flags)) {
                return 0;
        }
        return state->fn(rec, &id, msg_flags, state->private_data);
}

bool serverid_traverse(int (*fn)(struct db_record *rec,
                                 const struct server_id *id,
                                 uint32_t msg_flags, void *private_data),
                            void *private_data)
{
        struct db_context *db;
        struct serverid_traverse_state state;

        db = serverid_db();
        if (db == NULL) {
                return false;
        }
        state.fn = fn;
        state.private_data = private_data;
        return db->traverse(db, serverid_traverse_fn, &state);
}

uint64_t serverid_get_random_unique_id(void)
{
        uint64_t unique_id = SERVERID_UNIQUE_ID_NOT_TO_VERIFY;

        while (unique_id == SERVERID_UNIQUE_ID_NOT_TO_VERIFY) {
                generate_random_buffer((uint8_t *)&unique_id,
                                        sizeof(unique_id));
        }

        return unique_id;
}