/*
* $Id: snmpstats.c 1425 2006-12-18 22:22:51Z jmagder $
*
* SNMPStats Module
* Copyright (C) 2006 SOMA Networks, INC.
* Written by: Jeffrey Magder (jmagder@somanetworks.com)
*
* This file is part of openser, a free SIP server.
*
* openser 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
*
* openser 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)
*
* There are some important points to understanding the SNMPStat modules
* architecture.
*
* 1) The SNMPStats module will fork off a new process in mod_child_init when
* the rank is equal to PROC_MAIN_PROCESS. The sub-process will be
* responsible for registering with a master agent (the source of snmp
* requests), and handling all received requests.
*
* 2) The Module will register a periodic alarm checking function with a sip
* timer using register_timer(). This function checks for alarm conditions,
* and will send out traps to the master agent when it detects their
* presence.
*
* 3) The SNMPStats module is required to run an external application upon
* startup, to collect sysUpTime data from the master agent. This involves
* spawning a short-lived process. For this reason, the module temporarily
* installs a new SIGCHLD handler to deal specifically with this process. It
* does not change the normal SIGCHLD behaviour for any process except for
* this short lived sysUpTime process.
*
* 4) mod_init() will initialize some interprocess communication buffers, as
* well as callback mechanisms for the usrloc module. To understand what the
* interprocess buffer and callbacks are and are for, please see the comments
* at the beginning of openserSIPRegUserTable.c
*
*/
#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <signal.h>
#include <sys/wait.h>
#include "snmpstats.h"
#include "snmpstats_globals.h"
#include "../../timer.h"
#include <net-snmp/net-snmp-config.h>
#include <net-snmp/net-snmp-includes.h>
#include <net-snmp/agent/net-snmp-agent-includes.h>
#include "openserSIPRegUserTable.h"
#include "openserSIPContactTable.h"
#include "interprocess_buffer.h"
#include "hashTable.h"
#include "alarm_checks.h"
#include "utilities.h"
#include "sub_agent.h"
/* Required in every OpenSER Module. */
MODULE_VERSION
/*
* The module will fork off a child process to run an snmp command via execve().
* We need a customized handler to ignore the SIGCHLD when the execve()
* finishes. We keep around the child process's pid for the customized
* handler.
*
* Specifically, If the process that generated the SIGCHLD doesn't match this
* pid, we call OpenSER's default handlers. Otherwise, we just ignore SIGCHLD.
*/
volatile pid_t sysUpTime_pid;
/* The functions spawns a sysUpTime child. See the function definition below
* for a full description. */
static int spawn_sysUpTime_child();
/* Storage for the "snmpgetPath" and "snmpCommunity" openser.cfg parameters.
* The parameters are used to define what happens with the sysUpTime child. */
char *snmpget_path = NULL;
char *snmp_community = NULL;
/*
* This module replaces the default SIGCHLD handler with our own, as explained
* in the documentation for sysUpTime_pid above. This structure holds the old
* handler so we can call and restore OpenSER's usual handler when appropriate
*/
static struct sigaction old_sigchld_handler;
/* The following message codes are from Wikipedia at:
*
* http://en.wikipedia.org/wiki/SIP_Responses
*
* If there are more message codes added at a later time, they should be added
* here, and to out_message_code_names below.
*
* The array is used to register the statistics keeping track of the number of
* messages received with the response code X.
*/
char *in_message_code_names[] =
{
"100_in", "180_in", "181_in", "182_in", "183_in",
"200_in", "202_in",
"300_in", "301_in", "302_in", "305_in", "380_in",
"400_in", "401_in", "402_in", "403_in", "404_in", "405_in", "406_in",
"407_in", "408_in", "410_in", "413_in", "414_in", "415_in", "416_in",
"420_in", "421_in", "423_in", "480_in", "481_in", "482_in", "483_in",
"484_in", "485_in", "486_in", "487_in", "488_in", "491_in", "492_in",
"494_in",
"500_in", "501_in", "502_in", "503_in", "504_in", "505_in", "513_in",
"600_in", "603_in", "604_in", "606_in"
};
/* The following message codes are from Wikipedia at:
*
* http://en.wikipedia.org/wiki/SIP_Responses
*
* If there are more message codes added at a later time, they should be added
* here, and to in_message_code_names above.
*
* The array is used to register the statistics keeping track of the number of
* messages send out with the response code X.
*/
char *out_message_code_names[] =
{
"100_out", "180_out", "181_out", "182_out", "183_out",
"200_out", "202_out",
"300_out", "301_out", "302_out", "305_out", "380_out",
"400_out", "401_out", "402_out", "403_out", "404_out", "405_out", "406_out",
"407_out", "408_out", "410_out", "413_out", "414_out", "415_out", "416_out",
"420_out", "421_out", "423_out", "480_out", "481_out", "482_out", "483_out",
"484_out", "485_out", "486_out", "487_out", "488_out", "491_out", "492_out",
"494_out",
"500_out", "501_out", "502_out", "503_out", "504_out", "505_out", "513_out",
"600_out", "603_out", "604_out", "606_out"
};
/* message_code_stat_array[0] will be the data source for message_code_array[0]
* message_code_stat_array[3] will be the data source for message_code_array[3]
* and so on. */
stat_var **in_message_code_stats = NULL;
stat_var **out_message_code_stats = NULL;
/* Adds the message code statistics to the statistics framework */
static int register_message_code_statistics()
{
int i;
int number_of_message_codes =
sizeof(in_message_code_names) / sizeof(char *);
in_message_code_stats =
shm_malloc(sizeof(stat_var) * number_of_message_codes);
out_message_code_stats =
shm_malloc(sizeof(stat_var) * number_of_message_codes);
/* We can only proceed if we had enough memory to allocate the
* statistics. Note that we don't free the memory, but we don't care
* because the system is going to shut down */
if (in_message_code_stats == NULL ||
out_message_code_stats == NULL)
{
return -1;
}
/* Make sure everything is zeroed out */
memset(in_message_code_stats, 0, number_of_message_codes);
memset(out_message_code_stats, 0, number_of_message_codes);
for (i = 0; i < number_of_message_codes; i++)
{
register_stat(SNMPSTATS_MODULE_NAME, in_message_code_names[i],
&in_message_code_stats[i], 0);
register_stat(SNMPSTATS_MODULE_NAME, out_message_code_names[i],
&out_message_code_stats[i], 0);
}
return 0;
}
/* This is the first function to be called by OpenSER, to initialize the module.
* This call must always return a value as soon as possible. If it were not to
* return, then OpenSER would not be able to initialize any of the other
* modules. */
static int mod_init(void)
{
LOG(L_INFO, "INFO: SNMPStats: Starting up the SNMPStats Module\n");
if (register_message_code_statistics() < 0)
{
return -1;
}
/* Initialize shared memory used to buffer communication between the
* usrloc module and the snmpstats module. */
initInterprocessBuffers();
/* We need to register for callbacks with usrloc module, for whenever a
* contact is added or removed from the system. We need to do it now
* before OpenSER's functions get a chance to load up old user data from
* the database. That load will happen if a lookup() function is come
* across in openser.cfg. */
if (!registerForUSRLOCCallbacks())
{
/* Originally there were descriptive error messages here to help
* the operator debug problems. Turns out this may instead
* alarm them about problems they don't need to worry about. So
* the messages are commented out for now */
/*
LOG(L_ERR, "ERROR: snmpstats module was unable to register callbacks"
" with the usrloc module\n");
LOG(L_ERR, " Are you sure that the usrloc module was loaded"
"before the snmpstats module in ");
LOG(L_ERR, " openser.cfg? openserSIPRegUserTable will not be "
"updated.");
*/
}
/* Register the alarm checking function to run periodically */
register_timer(run_alarm_check, 0, ALARM_AGENT_FREQUENCY_IN_SECONDS);
return 0;
}
/* This function is called when OpenSER has finished creating all instances of
* itself. It is at this point that we want to create our AgentX sub-agent
* process, and register a handler for any state changes of our child. */
static int mod_child_init(int rank)
{
/* We only want to setup a single process, under the main attendant. */
if (rank != PROC_MAIN) {
return 0;
}
/* If we couldn't spawn a child, we can't continue. */
if (spawn_agentx_child() != 0) {
return -1;
}
/* Spawn a child that will check the system up time. */
spawn_sysUpTime_child();
return 0;
}
/* This function is called when OpenSER is shutting down. When this happens, we
* log a useful message and kill the AgentX Sub-Agent child process */
static void mod_destroy()
{
LOG(L_INFO, "INFO: SNMPStats: The SNMPStats module got the kill "
"signal\n");
LOG(L_INFO, " Shutting down the AgentX Sub-Agent!\n");
}
/* The SNMPStats module forks off a child process to run an snmp command via
* execve(). We need a customized handler to catch and ignore its SIGCHLD when it
* terminates. We also need to make sure to forward other processes SIGCHLD's to
* OpenSER's usual SIGCHLD handler. We do this by resetting back OpenSER's own
* signal handlers after we caught our appropriate SIGCHLD. */
static void sigchld_handler(int signal)
{
int pid_of_signalled_process_status;
int pid_of_signalled_process;
/* We need to lookout for the expected SIGCHLD from our
* sysUpTime child process, and ignore it. If the SIGCHLD is
* from another process, we need to call OpenSER's usual
* handlers */
pid_of_signalled_process =
waitpid(-1, &pid_of_signalled_process_status, WNOHANG);
if (pid_of_signalled_process == sysUpTime_pid)
{
/* It was the sysUpTime process which died, which was expected.
* At this point we will never see any SIGCHLDs from any other
* SNMPStats process. This means that we can restore OpenSER's
* original handlers. */
sigaction(SIGCHLD, &old_sigchld_handler, NULL);
} else
{
/* We need this 'else-block' in case another OpenSER process dies
* unexpectantly before the sysUpTime process dies. If this
* doesn't happen, then this code will never be called, because
* the block above re-assigns OpenSER's original SIGCHLD
* handler. If it does happen, then we make sure to call the
* default signal handlers. */
if (old_sigchld_handler.sa_handler != SIG_IGN &&
old_sigchld_handler.sa_handler != SIG_DFL)
{
(*(old_sigchld_handler.sa_handler))(signal);
}
}
}
/*
* This function will spawn a child that retrieves the sysUpTime, and stores the
* result in a file. This file will be read by the AgentX Sub-agent process to
* supply the openserSIPServiceStartTime time. This function never returns,
* but it will generated a SIGCHLD when it terminates. There must a SIGCHLD
* handler to ignore the SIGCHLD for only this process. (See sigchld_handler
* above).
*
* NOTE: sysUpTime is a scalar provided by netsnmp. It is not the same thing as
* a normal system uptime. Support for this has been provided to try to
* match the IETF Draft SIP MIBs as closely as possible.
*/
static int spawn_sysUpTime_child()
{
struct sigaction new_sigchld_handler;
char *local_path_to_snmpget = "/usr/local/bin/";
char *snmpget_binary_name = "/snmpget";
char *full_path_to_snmpget = NULL;
char *snmp_community_string = "public";
/* Set up a new SIGCHLD handler. The handler will be responsible for
* ignoring SIGCHLDs generated by our sysUpTime child process. Every
* other SIGCHLD will be redirected to the old SIGCHLD handler. */
sigfillset(&new_sigchld_handler.sa_mask);
new_sigchld_handler.sa_flags = SA_RESTART;
new_sigchld_handler.sa_handler = sigchld_handler;
sigaction(SIGCHLD, &new_sigchld_handler, &old_sigchld_handler);
int result_pid = fork();
if (result_pid < 0) {
LOG(L_ERR, "ERROR: SNMPStats: Could not spawn an agent to "
"check sysUpTime\n");
return -1;
} else if (result_pid != 0) {
/* Keep around the PID of the sysUpTime process so that the
* customized SIGCHLD handler knows to ignore the SIGCHLD we
* generate when we terminate. */
sysUpTime_pid = result_pid;
return 0;
}
/* If we are here, then we are the child process. Lets set up the file
* descriptors so we can capture the output of snmpget. */
int snmpget_fd =
open(SNMPGET_TEMP_FILE, O_CREAT|O_TRUNC|O_RDWR,
S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH);
if (snmpget_fd == -1) {
LOG(L_ERR, "ERROR: SNMPStats: Could not open a temporary file "
"for snmpget to write to\n");
return -1;
}
/* Redirect Standard Output to our temporary file. */
dup2(snmpget_fd, 1);
if (snmp_community != NULL) {
snmp_community_string = snmp_community;
} else {
LOG(L_INFO, "INFO: SNMPStats: An snmpCommunity parameter was"
" not provided. Defaulting to %s\n",
snmp_community_string);
}
char *args[] = {"-Ov", "-c", snmp_community_string, "localhost",
SYSUPTIME_OID, (char *) 0};
/* Make sure we have a path to snmpget, so we can retrieve the
* sysUpTime. */
if (snmpget_path == NULL)
{
LOG(L_INFO, "INFO: SNMPStats: An snmpgetPath parameter was not"
" specified. Defaulting to %s\n",
local_path_to_snmpget);
}
else
{
local_path_to_snmpget = snmpget_path;
}
int local_path_to_snmpget_length = strlen(local_path_to_snmpget);
int snmpget_binary_name_length = strlen(snmpget_binary_name);
/* Allocate enough memory to hold the path, the binary name, and the
* null character. We don't use pkg_memory here. */
full_path_to_snmpget =
malloc(sizeof(char) *
(local_path_to_snmpget_length +
snmpget_binary_name_length + 1));
if (full_path_to_snmpget == NULL)
{
LOG(L_ERR, "ERROR: SNMPStats: Ran out of memory while trying to"
" retrieve sysUpTime. ");
LOG(L_ERR, " openserSIPServiceStartTime is "
"defaulting to zero\n");
return -1;
}
else
{
/* Make a new string containing the full path to the binary. */
strcpy(full_path_to_snmpget, local_path_to_snmpget);
strcpy(&full_path_to_snmpget[local_path_to_snmpget_length],
snmpget_binary_name);
}
/* snmpget -Ov -c public localhost .1.3.6.1.2.1.1.3.0 */
if (execve(full_path_to_snmpget, args, NULL) == -1) {
LOG(L_ERR, "ERROR: SNMPStats: snmpget failed to run. Did you "
"supply the snmpstats\n");
LOG(L_ERR, " module with a proper snmpgetPath parameter?"
" The \n");
LOG(L_ERR, " openserSIPServiceStartTime is defaulting to "
"zero\n");
close(snmpget_fd);
free(full_path_to_snmpget);
exit(-1);
}
/* We should never be able to get here, because execve() is never
* supposed to return. */
free(full_path_to_snmpget);
exit(-1);
}
/* This function is called whenever the openser.cfg file specifies the
* snmpgetPath parameter. The function will set the snmpget_path parameter. */
int set_snmpget_path( modparam_t type, void *val)
{
if (!stringHandlerSanityCheck(type, val, "snmpgetPath" )) {
return -1;
}
snmpget_path = (char *)val;
return 0;
}
/* Handles setting of the snmp community string. */
int set_snmp_community( modparam_t type, void *val)
{
if (!stringHandlerSanityCheck(type, val, "snmpCommunity")) {
return -1;
}
snmp_community = (char *)val;
return 0;
}
syntax highlighted by Code2HTML, v. 0.9.1