freebsd-dev/contrib/ntp/ntpd/ntp_monitor.c

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1999-12-09 13:01:21 +00:00
/*
* ntp_monitor.c - monitor who is using the ntpd server
*/
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#ifdef HAVE_CONFIG_H
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# include <config.h>
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#endif
#include "ntpd.h"
#include "ntp_io.h"
#include "ntp_if.h"
#include "ntp_stdlib.h"
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#include <stdio.h>
#include <signal.h>
#ifdef HAVE_SYS_IOCTL_H
# include <sys/ioctl.h>
#endif
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/*
* I'm still not sure I like what I've done here. It certainly consumes
* memory like it is going out of style, and also may not be as low
* overhead as I'd imagined.
*
* Anyway, we record statistics based on source address, mode and version
* (for now, anyway. Check the code). The receive procedure calls us with
* the incoming rbufp before it does anything else.
*
* Each entry is doubly linked into two lists, a hash table and a
* most-recently-used list. When a packet arrives it is looked up
* in the hash table. If found, the statistics are updated and the
* entry relinked at the head of the MRU list. If not found, a new
* entry is allocated, initialized and linked into both the hash
* table and at the head of the MRU list.
*
* Memory is usually allocated by grabbing a big chunk of new memory
* and cutting it up into littler pieces. The exception to this when we
* hit the memory limit. Then we free memory by grabbing entries off
* the tail for the MRU list, unlinking from the hash table, and
* reinitializing.
*
* trimmed back memory consumption ... jdg 8/94
*/
/*
* Limits on the number of structures allocated. This limit is picked
* with the illicit knowlege that we can only return somewhat less
* than 8K bytes in a mode 7 response packet, and that each structure
* will require about 20 bytes of space in the response.
*
* ... I don't believe the above is true anymore ... jdg
*/
#ifndef MAXMONMEM
#define MAXMONMEM 600 /* we allocate up to 600 structures */
#endif
#ifndef MONMEMINC
#define MONMEMINC 40 /* allocate them 40 at a time */
#endif
/*
* Hashing stuff
*/
#define MON_HASH_SIZE 128
#define MON_HASH_MASK (MON_HASH_SIZE-1)
#define MON_HASH(addr) ((int)(ntohl((addr)) & MON_HASH_MASK))
/*
* Pointers to the hash table, the MRU list and the count table. Memory
* for the hash and count tables is only allocated if monitoring is turned on.
*/
static struct mon_data *mon_hash[MON_HASH_SIZE]; /* array of list ptrs */
struct mon_data mon_mru_list;
struct mon_data mon_fifo_list;
/*
* List of free structures structures, and counters of free and total
* structures. The free structures are linked with the hash_next field.
*/
static struct mon_data *mon_free; /* the free list or null if none */
static int mon_total_mem; /* total number of structures allocated */
static int mon_mem_increments; /* number of times we've called malloc() */
/*
* Initialization state. We may be monitoring, we may not. If
* we aren't, we may not even have allocated any memory yet.
*/
int mon_enabled;
static int mon_have_memory;
static void mon_getmoremem P((void));
static void remove_from_hash P((struct mon_data *));
/*
* init_mon - initialize monitoring global data
*/
void
init_mon(void)
{
/*
* Don't do much of anything here. We don't allocate memory
* until someone explicitly starts us.
*/
mon_enabled = MON_OFF;
mon_have_memory = 0;
mon_total_mem = 0;
mon_mem_increments = 0;
mon_free = NULL;
memset((char *)&mon_hash[0], 0, sizeof mon_hash);
memset((char *)&mon_mru_list, 0, sizeof mon_mru_list);
memset((char *)&mon_fifo_list, 0, sizeof mon_fifo_list);
}
/*
* mon_start - start up the monitoring software
*/
void
mon_start(
int mode
)
{
if (mon_enabled != MON_OFF) {
mon_enabled |= mode;
return;
}
if (mode == MON_OFF)
return; /* Ooops.. */
if (!mon_have_memory) {
mon_total_mem = 0;
mon_mem_increments = 0;
mon_free = NULL;
mon_getmoremem();
mon_have_memory = 1;
}
mon_mru_list.mru_next = &mon_mru_list;
mon_mru_list.mru_prev = &mon_mru_list;
mon_fifo_list.fifo_next = &mon_fifo_list;
mon_fifo_list.fifo_prev = &mon_fifo_list;
mon_enabled = mode;
}
/*
* mon_stop - stop the monitoring software
*/
void
mon_stop(
int mode
)
{
register struct mon_data *md, *md_next;
register int i;
if (mon_enabled == MON_OFF)
return;
if ((mon_enabled & mode) == 0 || mode == MON_OFF)
return;
mon_enabled &= ~mode;
if (mon_enabled != MON_OFF)
return;
/*
* Put everything back on the free list
*/
for (i = 0; i < MON_HASH_SIZE; i++) {
md = mon_hash[i]; /* get next list */
mon_hash[i] = NULL; /* zero the list head */
while (md != NULL) {
md_next = md->hash_next;
md->hash_next = mon_free;
mon_free = md;
md = md_next;
}
}
mon_mru_list.mru_next = &mon_mru_list;
mon_mru_list.mru_prev = &mon_mru_list;
mon_fifo_list.fifo_next = &mon_fifo_list;
mon_fifo_list.fifo_prev = &mon_fifo_list;
}
/*
* ntp_monitor - record stats about this packet
*/
void
ntp_monitor(
struct recvbuf *rbufp
)
{
register struct pkt *pkt;
register struct mon_data *md;
register u_long netnum;
register int hash;
register int mode;
if (mon_enabled == MON_OFF)
return;
pkt = &rbufp->recv_pkt;
netnum = NSRCADR(&rbufp->recv_srcadr);
hash = MON_HASH(netnum);
mode = PKT_MODE(pkt->li_vn_mode);
md = mon_hash[hash];
while (md != NULL) {
if (md->rmtadr == netnum &&
/* ?? md->interface == rbufp->dstadr && ?? */
md->mode == (u_char)mode) {
md->lasttime = current_time;
md->count++;
md->version = PKT_VERSION(pkt->li_vn_mode);
md->rmtport = NSRCPORT(&rbufp->recv_srcadr);
/*
* Shuffle him to the head of the
* mru list. What a crock.
*/
md->mru_next->mru_prev = md->mru_prev;
md->mru_prev->mru_next = md->mru_next;
md->mru_next = mon_mru_list.mru_next;
md->mru_prev = &mon_mru_list;
mon_mru_list.mru_next->mru_prev = md;
mon_mru_list.mru_next = md;
return;
}
md = md->hash_next;
}
/*
* If we got here, this is the first we've heard of this
* guy. Get him some memory, either from the free list
* or from the tail of the MRU list.
*/
if (mon_free == NULL && mon_total_mem >= MAXMONMEM) {
/*
* Get it from MRU list
*/
md = mon_mru_list.mru_prev;
md->mru_prev->mru_next = &mon_mru_list;
mon_mru_list.mru_prev = md->mru_prev;
remove_from_hash(md);
/*
* Get it from FIFO list
*/
md->fifo_prev->fifo_next = md->fifo_next;
md->fifo_next->fifo_prev = md->fifo_prev;
} else {
if (mon_free == NULL) /* if free list empty */
mon_getmoremem(); /* then get more */
md = mon_free;
mon_free = md->hash_next;
}
/*
* Got one, initialize it
*/
md->lasttime = md->firsttime = current_time;
md->lastdrop = 0;
md->count = 1;
md->rmtadr = netnum;
md->rmtport = NSRCPORT(&rbufp->recv_srcadr);
md->mode = (u_char) mode;
md->version = PKT_VERSION(pkt->li_vn_mode);
md->interface = rbufp->dstadr;
md->cast_flags = ((rbufp->dstadr->flags & INT_MULTICAST) &&
rbufp->fd == md->interface->fd) ? MDF_MCAST: rbufp->fd ==
md->interface->bfd ? MDF_BCAST : MDF_UCAST;
/*
* Drop him into front of the hash table.
* Also put him on top of the MRU list
* and at bottom of FIFO list
*/
md->hash_next = mon_hash[hash];
mon_hash[hash] = md;
md->mru_next = mon_mru_list.mru_next;
md->mru_prev = &mon_mru_list;
mon_mru_list.mru_next->mru_prev = md;
mon_mru_list.mru_next = md;
md->fifo_prev = mon_fifo_list.fifo_prev;
md->fifo_next = &mon_fifo_list;
mon_fifo_list.fifo_prev->fifo_next = md;
mon_fifo_list.fifo_prev = md;
}
/*
* mon_getmoremem - get more memory and put it on the free list
*/
static void
mon_getmoremem(void)
{
register struct mon_data *md;
register int i;
struct mon_data *freedata; /* 'old' free list (null) */
md = (struct mon_data *)emalloc(MONMEMINC * sizeof(struct mon_data));
freedata = mon_free;
mon_free = md;
for (i = 0; i < (MONMEMINC-1); i++) {
md->hash_next = (md + 1);
md++;
}
/*
* md now points at the last. Link in the rest of the chain.
*/
md->hash_next = freedata;
mon_total_mem += MONMEMINC;
mon_mem_increments++;
}
static void
remove_from_hash(
struct mon_data *md
)
{
register int hash;
register struct mon_data *md_prev;
hash = MON_HASH(md->rmtadr);
if (mon_hash[hash] == md) {
mon_hash[hash] = md->hash_next;
} else {
md_prev = mon_hash[hash];
while (md_prev->hash_next != md) {
md_prev = md_prev->hash_next;
if (md_prev == NULL) {
/* logic error */
return;
}
}
md_prev->hash_next = md->hash_next;
}
}