1: /*
2: * ntp_monitor - monitor ntpd statistics
3: */
4: #ifdef HAVE_CONFIG_H
5: # include <config.h>
6: #endif
7:
8: #include "ntpd.h"
9: #include "ntp_io.h"
10: #include "ntp_if.h"
11: #include "ntp_stdlib.h"
12: #include <ntp_random.h>
13:
14: #include <stdio.h>
15: #include <signal.h>
16: #ifdef HAVE_SYS_IOCTL_H
17: # include <sys/ioctl.h>
18: #endif
19:
20: /*
21: * Record statistics based on source address, mode and version. The
22: * receive procedure calls us with the incoming rbufp before it does
23: * anything else. While at it, implement rate controls for inbound
24: * traffic.
25: *
26: * Each entry is doubly linked into two lists, a hash table and a most-
27: * recently-used (MRU) list. When a packet arrives it is looked up in
28: * the hash table. If found, the statistics are updated and the entry
29: * relinked at the head of the MRU list. If not found, a new entry is
30: * allocated, initialized and linked into both the hash table and at the
31: * head of the MRU list.
32: *
33: * Memory is usually allocated by grabbing a big chunk of new memory and
34: * cutting it up into littler pieces. The exception to this when we hit
35: * the memory limit. Then we free memory by grabbing entries off the
36: * tail for the MRU list, unlinking from the hash table, and
37: * reinitializing.
38: */
39: /*
40: * Limits on the number of structures allocated. This limit is picked
41: * with the illicit knowlege that we can only return somewhat less than
42: * 8K bytes in a mode 7 response packet, and that each structure will
43: * require about 20 bytes of space in the response.
44: *
45: * ... I don't believe the above is true anymore ... jdg
46: */
47: #ifndef MAXMONMEM
48: #define MAXMONMEM 600 /* we allocate up to 600 structures */
49: #endif
50: #ifndef MONMEMINC
51: #define MONMEMINC 40 /* allocate them 40 at a time */
52: #endif
53:
54: /*
55: * Hashing stuff
56: */
57: #define MON_HASH_SIZE NTP_HASH_SIZE
58: #define MON_HASH_MASK NTP_HASH_MASK
59: #define MON_HASH(addr) NTP_HASH_ADDR(addr)
60:
61: /*
62: * Pointers to the hash table, the MRU list and the count table. Memory
63: * for the hash and count tables is only allocated if monitoring is
64: * turned on.
65: */
66: static struct mon_data *mon_hash[MON_HASH_SIZE]; /* list ptrs */
67: struct mon_data mon_mru_list;
68:
69: /*
70: * List of free structures structures, and counters of free and total
71: * structures. The free structures are linked with the hash_next field.
72: */
73: static struct mon_data *mon_free; /* free list or null if none */
74: static int mon_total_mem; /* total structures allocated */
75: static int mon_mem_increments; /* times called malloc() */
76:
77: /*
78: * Parameters of the RES_LIMITED restriction option. We define headway
79: * as the idle time between packets. A packet is discarded if the
80: * headway is less than the minimum, as well as if the average headway
81: * is less than eight times the increment.
82: */
83: int ntp_minpkt = NTP_MINPKT; /* minimum (log 2 s) */
84: int ntp_minpoll = NTP_MINPOLL; /* increment (log 2 s) */
85:
86: /*
87: * Initialization state. We may be monitoring, we may not. If
88: * we aren't, we may not even have allocated any memory yet.
89: */
90: int mon_enabled; /* enable switch */
91: int mon_age = 3000; /* preemption limit */
92: static int mon_have_memory;
93: static void mon_getmoremem (void);
94: static void remove_from_hash (struct mon_data *);
95:
96: /*
97: * init_mon - initialize monitoring global data
98: */
99: void
100: init_mon(void)
101: {
102: /*
103: * Don't do much of anything here. We don't allocate memory
104: * until someone explicitly starts us.
105: */
106: mon_enabled = MON_OFF;
107: mon_have_memory = 0;
108: mon_total_mem = 0;
109: mon_mem_increments = 0;
110: mon_free = NULL;
111: memset(&mon_hash[0], 0, sizeof mon_hash);
112: memset(&mon_mru_list, 0, sizeof mon_mru_list);
113: }
114:
115:
116: /*
117: * mon_start - start up the monitoring software
118: */
119: void
120: mon_start(
121: int mode
122: )
123: {
124:
125: if (mon_enabled != MON_OFF) {
126: mon_enabled |= mode;
127: return;
128: }
129: if (mode == MON_OFF)
130: return;
131:
132: if (!mon_have_memory) {
133: mon_total_mem = 0;
134: mon_mem_increments = 0;
135: mon_free = NULL;
136: mon_getmoremem();
137: mon_have_memory = 1;
138: }
139:
140: mon_mru_list.mru_next = &mon_mru_list;
141: mon_mru_list.mru_prev = &mon_mru_list;
142: mon_enabled = mode;
143: }
144:
145:
146: /*
147: * mon_stop - stop the monitoring software
148: */
149: void
150: mon_stop(
151: int mode
152: )
153: {
154: register struct mon_data *md, *md_next;
155: register int i;
156:
157: if (mon_enabled == MON_OFF)
158: return;
159: if ((mon_enabled & mode) == 0 || mode == MON_OFF)
160: return;
161:
162: mon_enabled &= ~mode;
163: if (mon_enabled != MON_OFF)
164: return;
165:
166: /*
167: * Put everything back on the free list
168: */
169: for (i = 0; i < MON_HASH_SIZE; i++) {
170: md = mon_hash[i]; /* get next list */
171: mon_hash[i] = NULL; /* zero the list head */
172: while (md != NULL) {
173: md_next = md->hash_next;
174: md->hash_next = mon_free;
175: mon_free = md;
176: md = md_next;
177: }
178: }
179: mon_mru_list.mru_next = &mon_mru_list;
180: mon_mru_list.mru_prev = &mon_mru_list;
181: }
182:
183: void
184: ntp_monclearinterface(struct interface *interface)
185: {
186: struct mon_data *md;
187:
188: for (md = mon_mru_list.mru_next; md != &mon_mru_list;
189: md = md->mru_next) {
190: if (md->interface == interface) {
191: /* dequeue from mru list and put to free list */
192: md->mru_prev->mru_next = md->mru_next;
193: md->mru_next->mru_prev = md->mru_prev;
194: remove_from_hash(md);
195: md->hash_next = mon_free;
196: mon_free = md;
197: }
198: }
199: }
200:
201:
202: /*
203: * ntp_monitor - record stats about this packet
204: *
205: * Returns flags
206: */
207: int
208: ntp_monitor(
209: struct recvbuf *rbufp,
210: int flags
211: )
212: {
213: register struct pkt *pkt;
214: register struct mon_data *md;
215: sockaddr_u addr;
216: register u_int hash;
217: register int mode;
218: int interval;
219:
220: if (mon_enabled == MON_OFF)
221: return (flags);
222:
223: pkt = &rbufp->recv_pkt;
224: memset(&addr, 0, sizeof(addr));
225: memcpy(&addr, &(rbufp->recv_srcadr), sizeof(addr));
226: hash = MON_HASH(&addr);
227: mode = PKT_MODE(pkt->li_vn_mode);
228: md = mon_hash[hash];
229: while (md != NULL) {
230: int head; /* headway increment */
231: int leak; /* new headway */
232: int limit; /* average threshold */
233:
234: /*
235: * Match address only to conserve MRU size.
236: */
237: if (SOCK_EQ(&md->rmtadr, &addr)) {
238: interval = current_time - md->lasttime;
239: md->lasttime = current_time;
240: md->count++;
241: md->flags = flags;
242: md->rmtport = NSRCPORT(&rbufp->recv_srcadr);
243: md->mode = (u_char) mode;
244: md->version = PKT_VERSION(pkt->li_vn_mode);
245:
246: /*
247: * Shuffle to the head of the MRU list.
248: */
249: md->mru_next->mru_prev = md->mru_prev;
250: md->mru_prev->mru_next = md->mru_next;
251: md->mru_next = mon_mru_list.mru_next;
252: md->mru_prev = &mon_mru_list;
253: mon_mru_list.mru_next->mru_prev = md;
254: mon_mru_list.mru_next = md;
255:
256: /*
257: * At this point the most recent arrival is
258: * first in the MRU list. Decrease the counter
259: * by the headway, but not less than zero.
260: */
261: md->leak -= interval;
262: if (md->leak < 0)
263: md->leak = 0;
264: head = 1 << ntp_minpoll;
265: leak = md->leak + head;
266: limit = NTP_SHIFT * head;
267: #ifdef DEBUG
268: if (debug > 1)
269: printf("restrict: interval %d headway %d limit %d\n",
270: interval, leak, limit);
271: #endif
272:
273: /*
274: * If the minimum and average thresholds are not
275: * exceeded, douse the RES_LIMITED and RES_KOD
276: * bits and increase the counter by the headway
277: * increment. Note that we give a 1-s grace for
278: * the minimum threshold and a 2-s grace for the
279: * headway increment. If one or both thresholds
280: * are exceeded and the old counter is less than
281: * the average threshold, set the counter to the
282: * average threshold plus the inrcrment and
283: * leave the RES_KOD bit lit. Othewise, leave
284: * the counter alone and douse the RES_KOD bit.
285: * This rate-limits the KoDs to no less than the
286: * average headway.
287: */
288: if (interval + 1 >= (1 << ntp_minpkt) &&
289: leak < limit) {
290: md->leak = leak - 2;
291: md->flags &= ~(RES_LIMITED | RES_KOD);
292: } else if (md->leak < limit) {
293: md->leak = limit + head;
294: } else {
295: md->flags &= ~RES_KOD;
296: }
297: return (md->flags);
298: }
299: md = md->hash_next;
300: }
301:
302: /*
303: * If we got here, this is the first we've heard of this
304: * guy. Get him some memory, either from the free list
305: * or from the tail of the MRU list.
306: */
307: if (mon_free == NULL && mon_total_mem >= MAXMONMEM) {
308:
309: /*
310: * Preempt from the MRU list if old enough.
311: */
312: md = mon_mru_list.mru_prev;
313: if (ntp_random() / (2. * FRAC) > (double)(current_time
314: - md->lasttime) / mon_age)
315: return (flags & ~(RES_LIMITED | RES_KOD));
316:
317: md->mru_prev->mru_next = &mon_mru_list;
318: mon_mru_list.mru_prev = md->mru_prev;
319: remove_from_hash(md);
320: } else {
321: if (mon_free == NULL)
322: mon_getmoremem();
323: md = mon_free;
324: mon_free = md->hash_next;
325: }
326:
327: /*
328: * Got one, initialize it
329: */
330: md->lasttime = md->firsttime = current_time;
331: md->count = 1;
332: md->flags = flags & ~(RES_LIMITED | RES_KOD);
333: md->leak = 0;
334: memset(&md->rmtadr, 0, sizeof(md->rmtadr));
335: memcpy(&md->rmtadr, &addr, sizeof(addr));
336: md->rmtport = NSRCPORT(&rbufp->recv_srcadr);
337: md->mode = (u_char) mode;
338: md->version = PKT_VERSION(pkt->li_vn_mode);
339: md->interface = rbufp->dstadr;
340: md->cast_flags = (u_char)(((rbufp->dstadr->flags &
341: INT_MCASTOPEN) && rbufp->fd == md->interface->fd) ?
342: MDF_MCAST: rbufp->fd == md->interface->bfd ? MDF_BCAST :
343: MDF_UCAST);
344:
345: /*
346: * Drop him into front of the hash table. Also put him on top of
347: * the MRU list.
348: */
349: md->hash_next = mon_hash[hash];
350: mon_hash[hash] = md;
351: md->mru_next = mon_mru_list.mru_next;
352: md->mru_prev = &mon_mru_list;
353: mon_mru_list.mru_next->mru_prev = md;
354: mon_mru_list.mru_next = md;
355: return (md->flags);
356: }
357:
358:
359: /*
360: * mon_getmoremem - get more memory and put it on the free list
361: */
362: static void
363: mon_getmoremem(void)
364: {
365: register struct mon_data *md;
366: register int i;
367: struct mon_data *freedata; /* 'old' free list (null) */
368:
369: md = (struct mon_data *)emalloc(MONMEMINC *
370: sizeof(struct mon_data));
371: freedata = mon_free;
372: mon_free = md;
373: for (i = 0; i < (MONMEMINC-1); i++) {
374: md->hash_next = (md + 1);
375: md++;
376: }
377:
378: /*
379: * md now points at the last. Link in the rest of the chain.
380: */
381: md->hash_next = freedata;
382: mon_total_mem += MONMEMINC;
383: mon_mem_increments++;
384: }
385:
386: static void
387: remove_from_hash(
388: struct mon_data *md
389: )
390: {
391: register u_int hash;
392: register struct mon_data *md_prev;
393:
394: hash = MON_HASH(&md->rmtadr);
395: if (mon_hash[hash] == md) {
396: mon_hash[hash] = md->hash_next;
397: } else {
398: md_prev = mon_hash[hash];
399: while (md_prev->hash_next != md) {
400: md_prev = md_prev->hash_next;
401: if (md_prev == NULL) {
402: /* logic error */
403: return;
404: }
405: }
406: md_prev->hash_next = md->hash_next;
407: }
408: }
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