/*-
 * 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
 * hrNetworkTable
 */

#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/sysctl.h>

#include <net/if.h>
#include <net/if_mib.h>

#include <assert.h>
#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <ifaddrs.h>
#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>

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

#include <bsnmp/snmp_mibII.h>

/*
 * This structure is used to hold a SNMP table entry
 * for HOST-RESOURCES-MIB's hrNetworkTable
 */
struct network_entry {
        int32_t         index;
        int32_t         ifIndex;
        TAILQ_ENTRY(network_entry) link;
#define HR_NETWORK_FOUND                0x001
        uint32_t        flags;

};
TAILQ_HEAD(network_tbl, network_entry);

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

/* last (agent) tick when hrNetworkTable was updated */
static uint64_t network_tick;

/* maximum number of ticks between updates of network table */
uint32_t network_tbl_refresh = HR_NETWORK_TBL_REFRESH * 100;

/* Constants */
static const struct asn_oid OIDX_hrDeviceNetwork_c = OIDX_hrDeviceNetwork;

/**
 * Create a new entry into the network table
 */
static struct network_entry *
network_entry_create(const struct device_entry *devEntry)
{
        struct network_entry *entry;

        assert(devEntry != NULL);
        if (devEntry == NULL)
                return (NULL);

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

        memset(entry, 0, sizeof(*entry));
        entry->index = devEntry->index;
        INSERT_OBJECT_INT(entry, &network_tbl);

        return (entry);
}

/**
 * Delete an entry in the network table
 */
static void
network_entry_delete(struct network_entry* entry)
{

        TAILQ_REMOVE(&network_tbl, entry, link);
        free(entry);
}

/**
 * Fetch the interfaces from the mibII module, get their real name from the
 * kernel and try to find it in the device table.
 */
static void
network_get_interfaces(void)
{
        struct device_entry *dev;
        struct network_entry *net;
        struct mibif *ifp;
        int name[6];
        size_t len;
        char *dname;

        name[0] = CTL_NET;
        name[1] = PF_LINK;
        name[2] = NETLINK_GENERIC;
        name[3] = IFMIB_IFDATA;
        name[5] = IFDATA_DRIVERNAME;

        for (ifp = mib_first_if(); ifp != NULL; ifp = mib_next_if(ifp)) {
                HRDBG("%s %s", ifp->name, ifp->descr);

                name[4] = ifp->sysindex;

                /* get the original name */
                len = 0;
                if (sysctl(name, 6, NULL, &len, 0, 0) < 0) {
                        syslog(LOG_ERR, "sysctl(net.link.ifdata.%d."
                            "drivername): %m", ifp->sysindex);
                        continue;
                }
                if ((dname = malloc(len)) == NULL) {
                        syslog(LOG_ERR, "malloc: %m");
                        continue;
                }
                if (sysctl(name, 6, dname, &len, 0, 0) < 0) {
                        syslog(LOG_ERR, "sysctl(net.link.ifdata.%d."
                            "drivername): %m", ifp->sysindex);
                        free(dname);
                        continue;
                }

                HRDBG("got device %s (%s)", ifp->name, dname);

                if ((dev = device_find_by_name(dname)) == NULL) {
                        HRDBG("%s not in hrDeviceTable", dname);
                        free(dname);
                        continue;
                }
                HRDBG("%s found in hrDeviceTable", dname);

                dev->type = &OIDX_hrDeviceNetwork_c;
                dev->flags |= HR_DEVICE_IMMUTABLE;

                free(dname);

                /* Then check hrNetworkTable for this device */
                TAILQ_FOREACH(net, &network_tbl, link)
                        if (net->index == dev->index)
                                break;

                if (net == NULL && (net = network_entry_create(dev)) == NULL)
                        continue;

                net->flags |= HR_NETWORK_FOUND;
                net->ifIndex = ifp->index;
        }

        network_tick = this_tick;
}

/**
 * Finalization routine for hrNetworkTable.
 * It destroys the lists and frees any allocated heap memory.
 */
void
fini_network_tbl(void)
{
        struct network_entry *n1;

        while ((n1 = TAILQ_FIRST(&network_tbl)) != NULL) {
                TAILQ_REMOVE(&network_tbl, n1, link);
                free(n1);
        }
}

/**
 * Get the interface list from mibII only at this point to be sure that
 * it is there already.
 */
void
start_network_tbl(void)
{

        mib_refresh_iflist();
        network_get_interfaces();
}

/**
 * Refresh the table.
 */
static void
refresh_network_tbl(void)
{
        struct network_entry *entry, *entry_tmp;

        if (this_tick - network_tick < network_tbl_refresh) {
                HRDBG("no refresh needed");
                return;
        }

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

        network_get_interfaces();

        /*
         * Purge items that disappeared
         */
        TAILQ_FOREACH_SAFE(entry, &network_tbl, link, entry_tmp) {
                if (!(entry->flags & HR_NETWORK_FOUND))
                        network_entry_delete(entry);
        }

        HRDBG("refresh DONE");
}

/*
 * This is the implementation for a generated (by our SNMP tool)
 * function prototype, see hostres_tree.h
 * It handles the SNMP operations for hrNetworkTable
 */
int
op_hrNetworkTable(struct snmp_context *ctx __unused, struct snmp_value *value,
    u_int sub, u_int iidx __unused, enum snmp_op curr_op)
{
        struct network_entry *entry;

        refresh_network_tbl();

        switch (curr_op) {

        case SNMP_OP_GETNEXT:
                if ((entry = NEXT_OBJECT_INT(&network_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(&network_tbl,
                    &value->var, sub)) == NULL)
                        return (SNMP_ERR_NOSUCHNAME);
                goto get;

        case SNMP_OP_SET:
                if ((entry = FIND_OBJECT_INT(&network_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_hrNetworkIfIndex:
                value->v.integer = entry->ifIndex;
                return (SNMP_ERR_NOERROR);

        }
        abort();
}