sub_agent.c

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/*
 * $Id: sub_agent.c 4764 2008-08-28 14:41:06Z henningw $
 *
 * SNMPStats Module 
 * Copyright (C) 2006 SOMA Networks, INC.
 * Written by: Jeffrey Magder (jmagder@somanetworks.com)
 *
 * This file is part of Kamailio, a free SIP server.
 *
 * Kamailio 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
 *
 * Kamailio 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 02111-1307
 * USA
 *
 * History:
 * --------
 * 2006-11-23 initial version (jmagder)
 */

/*!
 * \file
 * \brief SNMP statistic module, master agent connection
 *
 * This file defines all functions required to establish a relationship with a
 * master agent.
 * \ingroup snmpstats
 * - Module: \ref snmpstats
 */


#include <sys/types.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>

#include "sub_agent.h"

/* Bring in the NetSNMP headers */
#include <net-snmp/net-snmp-config.h>
#include <net-snmp/net-snmp-includes.h>
#include <net-snmp/agent/net-snmp-agent-includes.h>

/* Bring in the initialization functions for all scalars */
#include "openserSIPCommonObjects.h"
#include "openserSIPServerObjects.h"
#include "openserObjects.h"

/* Bring in the initialization functions for all tables */
#include "openserSIPPortTable.h"
#include "openserSIPMethodSupportedTable.h"
#include "openserSIPStatusCodesTable.h"
#include "openserSIPRegUserTable.h"
#include "openserSIPContactTable.h"
#include "openserSIPRegUserLookupTable.h"
#include "openserMIBNotifications.h"

#include "../../dprint.h"

static int keep_running;

/*! The function handles Handles shutting down of the sub_agent process. */
static void sigterm_handler(int signal) 
{
   /* Just exit.  The master agent will clean everything up for us */
   exit(0);
}

/*! This function:
 *
 *   1) Registers itself with the Master Agent
 *   2) Initializes all of the SNMPStats modules scalars and tables, while
 *      simultaneously registering their respective SNMP OID's and handlers 
 *      with the master agent.
 *   3) Repeatedly checks for new SNMP messages to process
 *
 * \note This function never returns, so it should always be called from a 
 *       sub-process.
 */
static int initialize_agentx(void) 
{
   /* We register with a master agent */
   register_with_master_agent(AGENT_PROCESS_NAME);
   
   /* Initialize all scalars, and let the master agent know we want to
    * handle all OID's pertaining to these scalars. */
   init_openserSIPCommonObjects();
   init_openserSIPServerObjects();
   init_openserObjects();

   /* Initialiaze all the tables, and let the master agent know we want to
    * handle all the OID's pertaining to these tables */
   init_openserSIPPortTable();
   init_openserSIPMethodSupportedTable();
   init_openserSIPStatusCodesTable();
   init_openserSIPRegUserTable();
   init_openserSIPContactTable();
   init_openserSIPRegUserLookupTable();

   /* In case we recevie a request to stop (kill -TERM or kill -INT) */
   keep_running = 1;

   while(keep_running) {
      agent_check_and_process(1); /* 0 == don't block */
   }

   snmp_shutdown(AGENT_PROCESS_NAME);
   SOCK_CLEANUP;
   exit (0);

   return 0;
}

/*! Creates a child that will become the AgentX sub-agent.  The child will
 * insulate itself from the rest of OpenSER by overriding most of signal
 * handlers. */
void agentx_child(int rank)
{
   struct sigaction new_sigterm_handler;
   struct sigaction default_handlers;
   struct sigaction sigpipe_handler;

   /* Setup a SIGTERM handler */
   sigfillset(&new_sigterm_handler.sa_mask);
   new_sigterm_handler.sa_flags   = 0;
   new_sigterm_handler.sa_handler = sigterm_handler;
   sigaction(SIGTERM, &new_sigterm_handler, NULL);

   /* We don't want OpenSER's normal handlers doing anything when
    * we die.  As far as OpenSER knows this process never existed.
    * So override all signal handlers to the OS default. */
   sigemptyset(&default_handlers.sa_mask);
   default_handlers.sa_flags = 0;
   default_handlers.sa_handler = SIG_DFL;

   sigaction(SIGCHLD, &default_handlers, NULL);
   sigaction(SIGINT,  &default_handlers, NULL);
   sigaction(SIGHUP,  &default_handlers, NULL);
   sigaction(SIGUSR1, &default_handlers, NULL);
   sigaction(SIGUSR2, &default_handlers, NULL);

   /* It is possible that the master agent will unregister us if we
    * take too long to respond to an SNMP request.  This would
    * happen if a large number of users/contacts have been
    * registered between snmp requests to the user/contact tables.
    * In this situation we may try to write to a closed socket when
    * we are done processing, resulting in a SIGPIPE.  This doesn't
    * need to be fatal however, because we can re-establish our
    * connection.  Therefore we set ourselves up to ignore the
    * SIGPIPE. */
   sigpipe_handler.sa_flags = SA_RESTART;
   sigpipe_handler.sa_handler = SIG_IGN;

   sigaction(SIGPIPE, &sigpipe_handler, NULL);

   initialize_agentx();
}



/*! This function opens up a connection with the master agent specified in
 * the snmpstats modules configuration file */
void register_with_master_agent(char *name_to_register_under) 
{
   /* Set ourselves up as an AgentX Client. */
   netsnmp_ds_set_boolean(NETSNMP_DS_APPLICATION_ID, NETSNMP_DS_AGENT_ROLE, 1);

   /* Initialize TCP if necessary.  (Its here for WIN32) compatibility. */
   SOCK_STARTUP;

   /* Read in our configuration file to determine master agent ping times
    * what port communication is to take place over, etc. */
   init_agent("snmpstats");

   /* Use a name we can register our agent under. */
   init_snmp(name_to_register_under);
}