/*
 * Copyright (c) 2005-2006 The FreeBSD Project
 * All rights reserved.
 *
 * Author: Victor Cruceru <soc-victor@freebsd.org>
 *
 * Redistribution of this software and documentation and use in source and
 * binary forms, with or without modification, are permitted provided that
 * the following conditions are met:
 *
 * 1. Redistributions of source code or documentation must retain the above
 *    copyright notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * Host Resources MIB implementation for SNMPd: instrumentation for
 * hrSWInstalledTable
 */

#include <sys/limits.h>
#include <sys/stat.h>
#include <sys/sysctl.h>
#include <sys/utsname.h>

#include <assert.h>
#include <dirent.h>
#include <err.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <sysexits.h>

#include "hostres_snmp.h"
#include "hostres_oid.h"
#include "hostres_tree.h"

#define CONTENTS_FNAME  "+CONTENTS"

enum SWInstalledType {
        SWI_UNKNOWN             = 1,
        SWI_OPERATING_SYSTEM    = 2,
        SWI_DEVICE_DRIVER       = 3,
        SWI_APPLICATION         = 4
};

#define SW_NAME_MLEN    (64 + 1)

/*
 * This structure is used to hold a SNMP table entry
 * for HOST-RESOURCES-MIB's hrSWInstalledTable
 */
struct swins_entry {
        int32_t         index;
        u_char          *name;  /* max len for this is SW_NAME_MLEN */
        const struct asn_oid *id;
        int32_t         type;   /* from enum SWInstalledType */
        u_char          date[11];
        u_int           date_len;

#define HR_SWINSTALLED_FOUND            0x001
#define HR_SWINSTALLED_IMMUTABLE        0x002
        uint32_t        flags;

        TAILQ_ENTRY(swins_entry) link;
};
TAILQ_HEAD(swins_tbl, swins_entry);

/*
 * Table to keep a conistent mapping between software and indexes.
 */
struct swins_map_entry {
        int32_t index;  /* swins_entry::index */
        u_char  *name;  /* map key,a copy of swins_entry::name*/

        /*
         * next may be NULL if the respective hrSWInstalledTblEntry
         * is (temporally) gone
         */
        struct swins_entry *entry;

        STAILQ_ENTRY(swins_map_entry) link;
};
STAILQ_HEAD(swins_map, swins_map_entry);

/* map for consistent indexing */
static struct swins_map swins_map = STAILQ_HEAD_INITIALIZER(swins_map);

/* the head of the list with hrSWInstalledTable's entries */
static struct swins_tbl swins_tbl = TAILQ_HEAD_INITIALIZER(swins_tbl);

/* next int available for indexing the hrSWInstalledTable */
static uint32_t next_swins_index = 1;

/* last (agent) tick when hrSWInstalledTable was updated */
static uint64_t swins_tick;

/* maximum number of ticks between updates of network table */
uint32_t swins_tbl_refresh = HR_SWINS_TBL_REFRESH * 100;

/* package directory */
u_char *pkg_dir;

/* last change of package list */
static time_t os_pkg_last_change;

/**
 * Create a new entry into the hrSWInstalledTable
 */
static struct swins_entry *
swins_entry_create(const char *name)
{
        struct swins_entry *entry;
        struct swins_map_entry *map;

        STAILQ_FOREACH(map, &swins_map, link)
                if (strcmp((const char *)map->name, name) == 0)
                        break;

        if (map == NULL) {
                size_t name_len;
                /* new object - get a new index */
                if (next_swins_index > INT_MAX) {
                        syslog(LOG_ERR, "%s: hrSWInstalledTable index wrap",
                            __func__ );
                        /* There isn't much we can do here.
                         * If the next_swins_index is consumed
                         * then we can't add entries to this table
                         * So it is better to exit - if the table is sparsed
                         * at the next agent run we can fill it fully.
                         */
                        errx(EX_SOFTWARE, "hrSWInstalledTable index wrap");
                }

                if ((map = malloc(sizeof(*map))) == NULL) {
                        syslog(LOG_ERR, "%s: %m", __func__ );
                        return (NULL);
                }

                name_len = strlen(name) + 1;
                if (name_len > SW_NAME_MLEN)
                         name_len = SW_NAME_MLEN;

                if ((map->name = malloc(name_len)) == NULL) {
                        syslog(LOG_WARNING, "%s: %m", __func__);
                        free(map);
                        return (NULL);
                }

                map->index = next_swins_index++;
                strlcpy((char *)map->name, name, name_len);

                STAILQ_INSERT_TAIL(&swins_map, map, link);

                HRDBG("%s added into hrSWInstalled at %d", name, map->index);
        }

        if ((entry = malloc(sizeof(*entry))) == NULL) {
                syslog(LOG_WARNING, "%s: %m", __func__);
                return (NULL);
        }
        memset(entry, 0, sizeof(*entry));

        if ((entry->name = strdup(map->name)) == NULL) {
                syslog(LOG_WARNING, "%s: %m", __func__);
                free(entry);
                return (NULL);
        }

        entry->index = map->index;
        map->entry = entry;

        INSERT_OBJECT_INT(entry, &swins_tbl);

        return (entry);
}

/**
 * Delete an entry in the hrSWInstalledTable
 */
static void
swins_entry_delete(struct swins_entry *entry)
{
        struct swins_map_entry *map;

        assert(entry != NULL);

        TAILQ_REMOVE(&swins_tbl, entry, link);

        STAILQ_FOREACH(map, &swins_map, link)
                if (map->entry == entry) {
                        map->entry = NULL;
                        break;
                }

        free(entry->name);
        free(entry);
}

/**
 * Find an entry given it's name
 */
static struct swins_entry *
swins_find_by_name(const char *name)
{
        struct swins_entry *entry;

        TAILQ_FOREACH(entry, &swins_tbl, link)
                if (strcmp((const char*)entry->name, name) == 0)
                        return (entry);
        return (NULL);
}

/**
 * Finalize this table
 */
void
fini_swins_tbl(void)
{
        struct swins_map_entry  *n1;

        while ((n1 = STAILQ_FIRST(&swins_map)) != NULL) {
                STAILQ_REMOVE_HEAD(&swins_map, link);
                if (n1->entry != NULL) {
                        TAILQ_REMOVE(&swins_tbl, n1->entry, link);
                        free(n1->entry->name);
                        free(n1->entry);
                }
                free(n1->name);
                free(n1);
        }
        assert(TAILQ_EMPTY(&swins_tbl));
}

/**
 * Get the *running* O/S identification
 */
static void
swins_get_OS_ident(void)
{
        struct utsname os_id;
        char os_string[SW_NAME_MLEN] = "";
        struct swins_entry *entry;
        u_char *boot;
        struct stat sb;
        struct tm k_ts;

        if (uname(&os_id) == -1) {
                syslog(LOG_WARNING, "%s: %m", __func__);
                return;
        }

        snprintf(os_string, sizeof(os_string), "%s: %s",
            os_id.sysname, os_id.version);

        if ((entry = swins_find_by_name(os_string)) != NULL ||
            (entry = swins_entry_create(os_string)) == NULL)
                return;

        entry->flags |= (HR_SWINSTALLED_FOUND | HR_SWINSTALLED_IMMUTABLE);
        entry->id = &oid_zeroDotZero;
        entry->type = (int32_t)SWI_OPERATING_SYSTEM;
        memset(entry->date, 0, sizeof(entry->date));

        if (OS_getSystemInitialLoadParameters(&boot) == SNMP_ERR_NOERROR &&
            strlen(boot) > 0 && stat(boot, &sb) == 0 &&
            localtime_r(&sb.st_ctime, &k_ts) != NULL)
                entry->date_len = make_date_time(entry->date, &k_ts, 0);
}

/**
 * Read the installed packages
 */
static int
swins_get_packages(void)
{
        struct stat sb;
        DIR *p_dir;
        struct dirent *ent;
        struct tm k_ts;
        char *pkg_file;
        struct swins_entry *entry;
        int ret = 0;

        if (pkg_dir == NULL)
                /* initialisation may have failed */
                return (-1);

        if (stat(pkg_dir, &sb) != 0) {
                syslog(LOG_ERR, "hrSWInstalledTable: stat(\"%s\") failed: %m",
                    pkg_dir);
                return (-1);
        }
        if (!S_ISDIR(sb.st_mode)) {
                syslog(LOG_ERR, "hrSWInstalledTable: \"%s\" is not a directory",
                    pkg_dir);
                return (-1);
        }
        if (sb.st_ctime <= os_pkg_last_change) {
                HRDBG("no need to rescan installed packages -- "
                    "directory time-stamp unmodified");

                TAILQ_FOREACH(entry, &swins_tbl, link)
                        entry->flags |= HR_SWINSTALLED_FOUND;

                return (0);
        }

        if ((p_dir = opendir(pkg_dir)) == NULL) {
                syslog(LOG_ERR, "hrSWInstalledTable: opendir(\"%s\") failed: "
                    "%m", pkg_dir);
                return (-1);
        }

        while (errno = 0, (ent = readdir(p_dir)) != NULL) {
                HRDBG("  pkg file: %s", ent->d_name);

                /* check that the contents file is a regular file */
                if (asprintf(&pkg_file, "%s/%s/%s", pkg_dir, ent->d_name,
                    CONTENTS_FNAME) == -1)
                        continue;

                if (stat(pkg_file, &sb) != 0 ) {
                        free(pkg_file);
                        continue;
                }

                if (!S_ISREG(sb.st_mode)) {
                        syslog(LOG_ERR, "hrSWInstalledTable: \"%s\" not a "
                            "regular file -- skipped", pkg_file);
                        free(pkg_file);
                        continue;
                }
                free(pkg_file);

                /* read directory timestamp on package */
                if (asprintf(&pkg_file, "%s/%s", pkg_dir, ent->d_name) == -1)
                        continue;

                if (stat(pkg_file, &sb) == -1 ||
                    localtime_r(&sb.st_ctime, &k_ts) == NULL) {
                        free(pkg_file);
                        continue;
                }
                free(pkg_file);

                /* update or create entry */
                if ((entry = swins_find_by_name(ent->d_name)) == NULL &&
                    (entry = swins_entry_create(ent->d_name)) == NULL) {
                        ret = -1;
                        goto PKG_LOOP_END;
                }

                entry->flags |= HR_SWINSTALLED_FOUND;
                entry->id = &oid_zeroDotZero;
                entry->type = (int32_t)SWI_APPLICATION;

                entry->date_len = make_date_time(entry->date, &k_ts, 0);
        }

        if (errno != 0) {
                syslog(LOG_ERR, "hrSWInstalledTable: readdir(\"%s\") failed:"
                    " %m", pkg_dir);
                ret = -1;
        } else {
                /*
                 * save the timestamp of directory
                 * to avoid any further scanning
                 */
                os_pkg_last_change = sb.st_ctime;
        }
  PKG_LOOP_END:
        (void)closedir(p_dir);
        return (ret);
}

/**
 * Refresh the installed software table.
 */
void
refresh_swins_tbl(void)
{
        int ret;
        struct swins_entry *entry, *entry_tmp;

        if (this_tick - swins_tick < swins_tbl_refresh) {
                HRDBG("no refresh needed");
                return;
        }

        /* mark each entry as missing */
        TAILQ_FOREACH(entry, &swins_tbl, link)
                entry->flags &= ~HR_SWINSTALLED_FOUND;

        ret = swins_get_packages();

        TAILQ_FOREACH_SAFE(entry, &swins_tbl, link, entry_tmp)
                if (!(entry->flags & HR_SWINSTALLED_FOUND) &&
                    !(entry->flags & HR_SWINSTALLED_IMMUTABLE))
                        swins_entry_delete(entry);

        if (ret == 0)
                swins_tick = this_tick;
}

/**
 * Create and populate the package table
 */
void
init_swins_tbl(void)
{

        if ((pkg_dir = malloc(sizeof(PATH_PKGDIR))) == NULL)
                syslog(LOG_ERR, "%s: %m", __func__);
        else
                strcpy(pkg_dir, PATH_PKGDIR);

        swins_get_OS_ident();
        refresh_swins_tbl();

        HRDBG("init done");
}

/**
 * SNMP handler
 */
int
op_hrSWInstalledTable(struct snmp_context *ctx __unused,
    struct snmp_value *value, u_int sub, u_int iidx __unused,
    enum snmp_op curr_op)
{
        struct swins_entry *entry;

        refresh_swins_tbl();

        switch (curr_op) {

          case SNMP_OP_GETNEXT:
                if ((entry = NEXT_OBJECT_INT(&swins_tbl,
                    &value->var, sub)) == NULL)
                        return (SNMP_ERR_NOSUCHNAME);
                value->var.len = sub + 1;
                value->var.subs[sub] = entry->index;
                goto get;

          case SNMP_OP_GET:
                if ((entry = FIND_OBJECT_INT(&swins_tbl,
                    &value->var, sub)) == NULL)
                        return (SNMP_ERR_NOSUCHNAME);
                goto get;

          case SNMP_OP_SET:
                if ((entry = FIND_OBJECT_INT(&swins_tbl,
                    &value->var, sub)) == NULL)
                        return (SNMP_ERR_NO_CREATION);
                return (SNMP_ERR_NOT_WRITEABLE);

          case SNMP_OP_ROLLBACK:
          case SNMP_OP_COMMIT:
                abort();
        }
        abort();

  get:
        switch (value->var.subs[sub - 1]) {

          case LEAF_hrSWInstalledIndex:
                value->v.integer = entry->index;
                return (SNMP_ERR_NOERROR);

          case LEAF_hrSWInstalledName:
                return (string_get(value, entry->name, -1));
                break;

          case LEAF_hrSWInstalledID:
                assert(entry->id != NULL);
                value->v.oid = *entry->id;
                return (SNMP_ERR_NOERROR);

          case LEAF_hrSWInstalledType:
                value->v.integer = entry->type;
                return (SNMP_ERR_NOERROR);

          case LEAF_hrSWInstalledDate:
                return (string_get(value, entry->date, entry->date_len));
        }
        abort();
}

/**
 * Scalars
 */
int
op_hrSWInstalled(struct snmp_context *ctx __unused,
    struct snmp_value *value __unused, u_int sub,
    u_int iidx __unused, enum snmp_op curr_op)
{

        /* only SNMP GET is possible */
        switch (curr_op) {

        case SNMP_OP_GET:
                goto get;

        case SNMP_OP_SET:
                return (SNMP_ERR_NOT_WRITEABLE);

        case SNMP_OP_ROLLBACK:
        case SNMP_OP_COMMIT:
        case SNMP_OP_GETNEXT:
                abort();
        }
        abort();

  get:
        switch (value->var.subs[sub - 1]) {

        case LEAF_hrSWInstalledLastChange:
        case LEAF_hrSWInstalledLastUpdateTime:
                /*
                 * We always update the entire table so these two tick
                 * values should be equal.
                 */
                refresh_swins_tbl();
                if (swins_tick <= start_tick)
                        value->v.uint32 = 0;
                else {
                        uint64_t lastChange = swins_tick - start_tick;

                        /* may overflow the SNMP type */
                        value->v.uint32 =
                            (lastChange > UINT_MAX ? UINT_MAX : lastChange);
                }

                return (SNMP_ERR_NOERROR);

        default:
                abort();
        }
}