/*
* snmp_alarm.c:
*/
/* Portions of this file are subject to the following copyright(s). See
* the Net-SNMP's COPYING file for more details and other copyrights
* that may apply:
*/
/*
* Portions of this file are copyrighted by:
* Copyright © 2003 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms specified in the COPYING file
* distributed with the Net-SNMP package.
*/
/** @defgroup snmp_alarm generic library based alarm timers for various parts of an application
* @ingroup library
*
* @{
*/
#include <net-snmp/net-snmp-config.h>
#if HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <signal.h>
#if HAVE_STDLIB_H
#include <stdlib.h>
#endif
#include <sys/types.h>
#if HAVE_NETINET_IN_H
#include <netinet/in.h>
#endif
#if HAVE_STRING_H
#include <string.h>
#endif
#if TIME_WITH_SYS_TIME
# include <sys/time.h>
# include <time.h>
#else
# if HAVE_SYS_TIME_H
# include <sys/time.h>
# else
# include <time.h>
# endif
#endif
#if HAVE_DMALLOC_H
#include <dmalloc.h>
#endif
#include <net-snmp/types.h>
#include <net-snmp/output_api.h>
#include <net-snmp/config_api.h>
#include <net-snmp/utilities.h>
#include <net-snmp/library/snmp_api.h>
#include <net-snmp/library/callback.h>
#include <net-snmp/library/snmp_alarm.h>
static struct snmp_alarm *thealarms = NULL;
static int start_alarms = 0;
static unsigned int regnum = 1;
int
init_alarm_post_config(int majorid, int minorid, void *serverarg,
void *clientarg)
{
start_alarms = 1;
set_an_alarm();
return SNMPERR_SUCCESS;
}
void
init_snmp_alarm(void)
{
start_alarms = 0;
snmp_register_callback(SNMP_CALLBACK_LIBRARY,
SNMP_CALLBACK_POST_READ_CONFIG,
init_alarm_post_config, NULL);
}
void
sa_update_entry(struct snmp_alarm *a)
{
if (!timerisset(&a->t_lastM)) {
/*
* First call of sa_update_entry() for alarm a: set t_lastM and t_nextM.
*/
netsnmp_get_monotonic_clock(&a->t_lastM);
NETSNMP_TIMERADD(&a->t_lastM, &a->t, &a->t_nextM);
} else if (!timerisset(&a->t_nextM)) {
/*
* We've been called but not reset for the next call.
*/
if (a->flags & SA_REPEAT) {
if (timerisset(&a->t)) {
NETSNMP_TIMERADD(&a->t_lastM, &a->t, &a->t_nextM);
} else {
DEBUGMSGTL(("snmp_alarm",
"update_entry: illegal interval specified\n"));
snmp_alarm_unregister(a->clientreg);
}
} else {
/*
* Single time call, remove it.
*/
snmp_alarm_unregister(a->clientreg);
}
}
}
/**
* This function removes the callback function from a list of registered
* alarms, unregistering the alarm.
*
* @param clientreg is a unique unsigned integer representing a registered
* alarm which the client wants to unregister.
*
* @return void
*
* @see snmp_alarm_register
* @see snmp_alarm_register_hr
* @see snmp_alarm_unregister_all
*/
void
snmp_alarm_unregister(unsigned int clientreg)
{
struct snmp_alarm *sa_ptr, **prevNext = &thealarms;
for (sa_ptr = thealarms;
sa_ptr != NULL && sa_ptr->clientreg != clientreg;
sa_ptr = sa_ptr->next) {
prevNext = &(sa_ptr->next);
}
if (sa_ptr != NULL) {
*prevNext = sa_ptr->next;
DEBUGMSGTL(("snmp_alarm", "unregistered alarm %d\n",
sa_ptr->clientreg));
/*
* Note: do not free the clientarg, it's the client's responsibility
*/
free(sa_ptr);
} else {
DEBUGMSGTL(("snmp_alarm", "no alarm %d to unregister\n", clientreg));
}
}
/**
* This function unregisters all alarms currently stored.
*
* @return void
*
* @see snmp_alarm_register
* @see snmp_alarm_register_hr
* @see snmp_alarm_unregister
*/
void
snmp_alarm_unregister_all(void)
{
struct snmp_alarm *sa_ptr, *sa_tmp;
for (sa_ptr = thealarms; sa_ptr != NULL; sa_ptr = sa_tmp) {
sa_tmp = sa_ptr->next;
free(sa_ptr);
}
DEBUGMSGTL(("snmp_alarm", "ALL alarms unregistered\n"));
thealarms = NULL;
}
struct snmp_alarm *
sa_find_next(void)
{
struct snmp_alarm *a, *lowest = NULL;
for (a = thealarms; a != NULL; a = a->next)
if (!(a->flags & SA_FIRED)
&& (lowest == NULL || timercmp(&a->t_nextM, &lowest->t_nextM, <)))
lowest = a;
return lowest;
}
NETSNMP_IMPORT struct snmp_alarm *sa_find_specific(unsigned int clientreg);
struct snmp_alarm *
sa_find_specific(unsigned int clientreg)
{
struct snmp_alarm *sa_ptr;
for (sa_ptr = thealarms; sa_ptr != NULL; sa_ptr = sa_ptr->next) {
if (sa_ptr->clientreg == clientreg) {
return sa_ptr;
}
}
return NULL;
}
void
run_alarms(void)
{
struct snmp_alarm *a;
unsigned int clientreg;
struct timeval t_now;
/*
* Loop through everything we have repeatedly looking for the next thing to
* call until all events are finally in the future again.
*/
while ((a = sa_find_next()) != NULL) {
netsnmp_get_monotonic_clock(&t_now);
if (timercmp(&a->t_nextM, &t_now, >))
return;
clientreg = a->clientreg;
a->flags |= SA_FIRED;
DEBUGMSGTL(("snmp_alarm", "run alarm %d\n", clientreg));
(*(a->thecallback)) (clientreg, a->clientarg);
DEBUGMSGTL(("snmp_alarm", "alarm %d completed\n", clientreg));
a = sa_find_specific(clientreg);
if (a) {
a->t_lastM = t_now;
timerclear(&a->t_nextM);
a->flags &= ~SA_FIRED;
sa_update_entry(a);
} else {
DEBUGMSGTL(("snmp_alarm", "alarm %d deleted itself\n",
clientreg));
}
}
}
RETSIGTYPE
alarm_handler(int a)
{
run_alarms();
set_an_alarm();
}
/**
* Look up the time at which the next alarm will fire.
*
* @param[out] alarm_tm Time at which the next alarm will fire.
* @param[in] now Earliest time that should be written into *alarm_tm.
*
* @return Zero if no alarms are scheduled; non-zero 'clientreg' value
* identifying the first alarm that will fire if one or more alarms are
* scheduled.
*/
int
netsnmp_get_next_alarm_time(struct timeval *alarm_tm, const struct timeval *now)
{
struct snmp_alarm *sa_ptr;
sa_ptr = sa_find_next();
if (sa_ptr) {
netsnmp_assert(alarm_tm);
netsnmp_assert(timerisset(&sa_ptr->t_nextM));
if (timercmp(&sa_ptr->t_nextM, now, >))
*alarm_tm = sa_ptr->t_nextM;
else
*alarm_tm = *now;
return sa_ptr->clientreg;
} else {
return 0;
}
}
/**
* Get the time until the next alarm will fire.
*
* @param[out] delta Time until the next alarm.
*
* @return Zero if no alarms are scheduled; non-zero 'clientreg' value
* identifying the first alarm that will fire if one or more alarms are
* scheduled.
*/
int
get_next_alarm_delay_time(struct timeval *delta)
{
struct timeval t_now, alarm_tm;
int res;
netsnmp_get_monotonic_clock(&t_now);
res = netsnmp_get_next_alarm_time(&alarm_tm, &t_now);
if (res)
NETSNMP_TIMERSUB(&alarm_tm, &t_now, delta);
return res;
}
void
set_an_alarm(void)
{
struct timeval delta;
int nextalarm = get_next_alarm_delay_time(&delta);
/*
* We don't use signals if they asked us nicely not to. It's expected
* they'll check the next alarm time and do their own calling of
* run_alarms().
*/
if (nextalarm && !netsnmp_ds_get_boolean(NETSNMP_DS_LIBRARY_ID,
NETSNMP_DS_LIB_ALARM_DONT_USE_SIG)) {
#ifndef WIN32
# ifdef HAVE_SETITIMER
struct itimerval it;
it.it_value = delta;
timerclear(&it.it_interval);
signal(SIGALRM, alarm_handler);
setitimer(ITIMER_REAL, &it, NULL);
DEBUGMSGTL(("snmp_alarm", "schedule alarm %d in %ld.%03ld seconds\n",
nextalarm, (long) delta.tv_sec, (long)(delta.tv_usec / 1000)));
# else /* HAVE_SETITIMER */
# ifdef SIGALRM
signal(SIGALRM, alarm_handler);
alarm(delta.tv_sec);
DEBUGMSGTL(("snmp_alarm",
"schedule alarm %d in roughly %ld seconds\n", nextalarm,
delta.tv_sec));
# endif /* SIGALRM */
# endif /* HAVE_SETITIMER */
#endif /* WIN32 */
} else {
DEBUGMSGTL(("snmp_alarm", "no alarms found to schedule\n"));
}
}
/**
* This function registers function callbacks to occur at a specific time
* in the future.
*
* @param when is an unsigned integer specifying when the callback function
* will be called in seconds.
*
* @param flags is an unsigned integer that specifies how frequent the callback
* function is called in seconds. Should be SA_REPEAT or 0. If
* flags is set with SA_REPEAT, then the registered callback function
* will be called every SA_REPEAT seconds. If flags is 0 then the
* function will only be called once and then removed from the
* registered alarm list.
*
* @param thecallback is a pointer SNMPAlarmCallback which is the callback
* function being stored and registered.
*
* @param clientarg is a void pointer used by the callback function. This
* pointer is assigned to snmp_alarm->clientarg and passed into the
* callback function for the client's specific needs.
*
* @return Returns a unique unsigned integer(which is also passed as the first
* argument of each callback), which can then be used to remove the
* callback from the list at a later point in the future using the
* snmp_alarm_unregister() function. If memory could not be allocated
* for the snmp_alarm struct 0 is returned.
*
* @see snmp_alarm_unregister
* @see snmp_alarm_register_hr
* @see snmp_alarm_unregister_all
*/
unsigned int
snmp_alarm_register(unsigned int when, unsigned int flags,
SNMPAlarmCallback * thecallback, void *clientarg)
{
struct timeval t;
if (0 == when) {
t.tv_sec = 0;
t.tv_usec = 1;
} else {
t.tv_sec = when;
t.tv_usec = 0;
}
return snmp_alarm_register_hr(t, flags, thecallback, clientarg);
}
/**
* This function offers finer granularity as to when the callback
* function is called by making use of t->tv_usec value forming the
* "when" aspect of snmp_alarm_register().
*
* @param t is a timeval structure used to specify when the callback
* function(alarm) will be called. Adds the ability to specify
* microseconds. t.tv_sec and t.tv_usec are assigned
* to snmp_alarm->tv_sec and snmp_alarm->tv_usec respectively internally.
* The snmp_alarm_register function only assigns seconds(it's when
* argument).
*
* @param flags is an unsigned integer that specifies how frequent the callback
* function is called in seconds. Should be SA_REPEAT or NULL. If
* flags is set with SA_REPEAT, then the registered callback function
* will be called every SA_REPEAT seconds. If flags is NULL then the
* function will only be called once and then removed from the
* registered alarm list.
*
* @param cb is a pointer SNMPAlarmCallback which is the callback
* function being stored and registered.
*
* @param cd is a void pointer used by the callback function. This
* pointer is assigned to snmp_alarm->clientarg and passed into the
* callback function for the client's specific needs.
*
* @return Returns a unique unsigned integer(which is also passed as the first
* argument of each callback), which can then be used to remove the
* callback from the list at a later point in the future using the
* snmp_alarm_unregister() function. If memory could not be allocated
* for the snmp_alarm struct 0 is returned.
*
* @see snmp_alarm_register
* @see snmp_alarm_unregister
* @see snmp_alarm_unregister_all
*/
unsigned int
snmp_alarm_register_hr(struct timeval t, unsigned int flags,
SNMPAlarmCallback * cb, void *cd)
{
struct snmp_alarm **s = NULL;
for (s = &(thealarms); *s != NULL; s = &((*s)->next));
*s = SNMP_MALLOC_STRUCT(snmp_alarm);
if (*s == NULL) {
return 0;
}
(*s)->t = t;
(*s)->flags = flags;
(*s)->clientarg = cd;
(*s)->thecallback = cb;
(*s)->clientreg = regnum++;
(*s)->next = NULL;
sa_update_entry(*s);
DEBUGMSGTL(("snmp_alarm",
"registered alarm %d, t = %ld.%03ld, flags=0x%02x\n",
(*s)->clientreg, (long) (*s)->t.tv_sec, (long)((*s)->t.tv_usec / 1000),
(*s)->flags));
if (start_alarms) {
set_an_alarm();
}
return (*s)->clientreg;
}
/**
* This function resets an existing alarm.
*
* @param clientreg is a unique unsigned integer representing a registered
* alarm which the client wants to unregister.
*
* @return 0 on success, -1 if the alarm was not found
*
* @see snmp_alarm_register
* @see snmp_alarm_register_hr
* @see snmp_alarm_unregister
*/
int
snmp_alarm_reset(unsigned int clientreg)
{
struct snmp_alarm *a;
struct timeval t_now;
if ((a = sa_find_specific(clientreg)) != NULL) {
netsnmp_get_monotonic_clock(&t_now);
a->t_lastM.tv_sec = t_now.tv_sec;
a->t_lastM.tv_usec = t_now.tv_usec;
a->t_nextM.tv_sec = 0;
a->t_nextM.tv_usec = 0;
NETSNMP_TIMERADD(&t_now, &a->t, &a->t_nextM);
return 0;
}
DEBUGMSGTL(("snmp_alarm_reset", "alarm %d not found\n",
clientreg));
return -1;
}
/** @} */