/*
 * DEBUG: section 34    Dnsserver interface
 * AUTHOR: Harvest Derived
 *
 * SQUID Web Proxy Cache          http://www.squid-cache.org/
 * ----------------------------------------------------------
 *
 *  Squid is the result of efforts by numerous individuals from
 *  the Internet community; see the CONTRIBUTORS file for full
 *  details.   Many organizations have provided support for Squid's
 *  development; see the SPONSORS file for full details.  Squid is
 *  Copyrighted (C) 2001 by the Regents of the University of
 *  California; see the COPYRIGHT file for full details.  Squid
 *  incorporates software developed and/or copyrighted by other
 *  sources; see the CREDITS file for full details.
 *
 *  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 2 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, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
 *
 */

#include "squid.h"
#include "helper.h"
#include "mgr/Registration.h"
#include "SquidConfig.h"
#include "SquidTime.h"
#include "Store.h"
#include "wordlist.h"

#if SQUID_SNMP
#include "snmp_core.h"
#endif

/* MS VisualStudio Projects are monolitich, so we need the following
   #if to include the external DNS code in compile process when
   using external DNS.
 */
#if USE_DNSHELPER

static helper *dnsservers = NULL;

static void
dnsStats(StoreEntry * sentry)
{
    storeAppendPrintf(sentry, "Dnsserver Statistics:\n");
    helperStats(sentry, dnsservers);
}

static void
dnsRegisterWithCacheManager(void)
{
    Mgr::RegisterAction("dns", "Dnsserver Statistics", dnsStats, 0, 1);
}

void
dnsInit(void)
{
    wordlist *w;

    dnsRegisterWithCacheManager();

    if (!Config.Program.dnsserver)
        return;

    if (dnsservers == NULL)
        dnsservers = new helper("dnsserver");

    dnsservers->childs.updateLimits(Config.dnsChildren);

    dnsservers->ipc_type = IPC_STREAM;

    assert(dnsservers->cmdline == NULL);

    wordlistAdd(&dnsservers->cmdline, Config.Program.dnsserver);

    if (Config.onoff.res_defnames)
        wordlistAdd(&dnsservers->cmdline, "-D");

    for (w = Config.dns_nameservers; w != NULL; w = w->next) {
        wordlistAdd(&dnsservers->cmdline, "-s");
        wordlistAdd(&dnsservers->cmdline, w->key);
    }

    helperOpenServers(dnsservers);
}

void
dnsShutdown(void)
{
    if (!dnsservers)
        return;

    helperShutdown(dnsservers);

    wordlistDestroy(&dnsservers->cmdline);

    if (!shutting_down)
        return;

    delete dnsservers;
    dnsservers = NULL;
}

void
dnsSubmit(const char *lookup, HLPCB * callback, void *data)
{
    char buf[256];
    static time_t first_warn = 0;
    snprintf(buf, 256, "%s\n", lookup);

    if (dnsservers->stats.queue_size >= (int)dnsservers->childs.n_active && dnsservers->childs.needNew() > 0) {
        helperOpenServers(dnsservers);
    }

    if (dnsservers->stats.queue_size >= (int)(dnsservers->childs.n_running * 2)) {
        if (first_warn == 0)
            first_warn = squid_curtime;

        if (squid_curtime - first_warn > 3 * 60)
            fatal("DNS servers not responding for 3 minutes");

        debugs(34, DBG_IMPORTANT, "dnsSubmit: queue overload, rejecting " << lookup);

        callback(data, (char *)"$fail Temporary network problem, please retry later");

        return;
    }

    first_warn = 0;
    helperSubmit(dnsservers, buf, callback, data);
}

#if SQUID_SNMP
/*
 * The function to return the DNS via SNMP
 */
variable_list *
snmp_netDnsFn(variable_list * Var, snint * ErrP)
{
    variable_list *Answer = NULL;
    MemBuf tmp;
    debugs(49, 5, "snmp_netDnsFn: Processing request: " << Var->name[LEN_SQ_NET + 1] << " " << snmpDebugOid(Var->name, Var->name_length, tmp));
    *ErrP = SNMP_ERR_NOERROR;

    switch (Var->name[LEN_SQ_NET + 1]) {

    case DNS_REQ:
        Answer = snmp_var_new_integer(Var->name, Var->name_length,
                                      dnsservers->stats.requests,
                                      SMI_COUNTER32);
        break;

    case DNS_REP:
        Answer = snmp_var_new_integer(Var->name, Var->name_length,
                                      dnsservers->stats.replies,
                                      SMI_COUNTER32);
        break;

    case DNS_SERVERS:
        Answer = snmp_var_new_integer(Var->name, Var->name_length,
                                      dnsservers->childs.n_running,
                                      SMI_COUNTER32);
        break;

    default:
        *ErrP = SNMP_ERR_NOSUCHNAME;
        break;
    }

    return Answer;
}

#endif /* SQUID_SNMP */
#endif /* USE_DNSHELPER */