xref: /freebsd/sys/netgraph/ng_car.c (revision 6ff6d951ade3f3379932df7f878ef3ea272cfc59)
1 /*-
2  * Copyright (c) 2005 Nuno Antunes <nuno.antunes@gmail.com>
3  * Copyright (c) 2007 Alexander Motin <mav@freebsd.org>
4  * All rights reserved.
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions
8  * are met:
9  * 1. Redistributions of source code must retain the above copyright
10  *    notice, this list of conditions and the following disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in the
13  *    documentation and/or other materials provided with the distribution.
14  *
15  * THIS SOFTWARE IS PROVIDED BY AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18  * ARE DISCLAIMED.  IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25  * SUCH DAMAGE.
26  *
27  * $FreeBSD$
28  */
29 
30 /*
31  * ng_car - An implementation of commited access rate for netgraph
32  *
33  * TODO:
34  *	- Sanitize input config values (impose some limits)
35  *	- Implement internal packet painting (possibly using mbuf tags)
36  *	- Implement color-aware mode
37  *	- Implement DSCP marking for IPv4
38  */
39 
40 #include <sys/param.h>
41 #include <sys/errno.h>
42 #include <sys/kernel.h>
43 #include <sys/malloc.h>
44 #include <sys/mbuf.h>
45 
46 #include <netgraph/ng_message.h>
47 #include <netgraph/ng_parse.h>
48 #include <netgraph/netgraph.h>
49 #include <netgraph/ng_car.h>
50 
51 #define NG_CAR_QUEUE_SIZE	100	/* Maximum queue size for SHAPE mode */
52 #define NG_CAR_QUEUE_MIN_TH	8	/* Minimum RED threshhold for SHAPE mode */
53 
54 /* Hook private info */
55 struct hookinfo {
56 	hook_p		hook;		/* this (source) hook */
57 	hook_p		dest;		/* destination hook */
58 
59 	int64_t 	tc;		/* commited token bucket counter */
60 	int64_t 	te;		/* exceeded/peak token bucket counter */
61 	struct bintime	lastRefill;	/* last token refill time */
62 
63 	struct ng_car_hookconf conf;	/* hook configuration */
64 	struct ng_car_hookstats stats;	/* hook stats */
65 
66 	struct mbuf	*q[NG_CAR_QUEUE_SIZE];	/* circular packet queue */
67 	u_int		q_first;	/* first queue element */
68 	u_int		q_last;		/* last queue element */
69 	struct callout	q_callout;	/* periodic queue processing routine */
70 	struct mtx	q_mtx;		/* queue mutex */
71 };
72 
73 /* Private information for each node instance */
74 struct privdata {
75 	node_p node;				/* the node itself */
76 	struct hookinfo upper;			/* hook to upper layers */
77 	struct hookinfo lower;			/* hook to lower layers */
78 };
79 typedef struct privdata *priv_p;
80 
81 static ng_constructor_t	ng_car_constructor;
82 static ng_rcvmsg_t	ng_car_rcvmsg;
83 static ng_shutdown_t	ng_car_shutdown;
84 static ng_newhook_t	ng_car_newhook;
85 static ng_rcvdata_t	ng_car_rcvdata;
86 static ng_disconnect_t	ng_car_disconnect;
87 
88 static void	ng_car_refillhook(struct hookinfo *h);
89 static void	ng_car_schedule(struct hookinfo *h);
90 void		ng_car_q_event(node_p node, hook_p hook, void *arg, int arg2);
91 static void	ng_car_enqueue(struct hookinfo *h, item_p item);
92 
93 /* Parse type for struct ng_car_hookstats */
94 static const struct ng_parse_struct_field ng_car_hookstats_type_fields[]
95 	= NG_CAR_HOOKSTATS;
96 static const struct ng_parse_type ng_car_hookstats_type = {
97 	&ng_parse_struct_type,
98 	&ng_car_hookstats_type_fields
99 };
100 
101 /* Parse type for struct ng_car_bulkstats */
102 static const struct ng_parse_struct_field ng_car_bulkstats_type_fields[]
103 	= NG_CAR_BULKSTATS(&ng_car_hookstats_type);
104 static const struct ng_parse_type ng_car_bulkstats_type = {
105 	&ng_parse_struct_type,
106 	&ng_car_bulkstats_type_fields
107 };
108 
109 /* Parse type for struct ng_car_hookconf */
110 static const struct ng_parse_struct_field ng_car_hookconf_type_fields[]
111 	= NG_CAR_HOOKCONF;
112 static const struct ng_parse_type ng_car_hookconf_type = {
113 	&ng_parse_struct_type,
114 	&ng_car_hookconf_type_fields
115 };
116 
117 /* Parse type for struct ng_car_bulkconf */
118 static const struct ng_parse_struct_field ng_car_bulkconf_type_fields[]
119 	= NG_CAR_BULKCONF(&ng_car_hookconf_type);
120 static const struct ng_parse_type ng_car_bulkconf_type = {
121 	&ng_parse_struct_type,
122 	&ng_car_bulkconf_type_fields
123 };
124 
125 /* Command list */
126 static struct ng_cmdlist ng_car_cmdlist[] = {
127 	{
128 	  NGM_CAR_COOKIE,
129 	  NGM_CAR_GET_STATS,
130 	  "getstats",
131 	  NULL,
132 	  &ng_car_bulkstats_type,
133 	},
134 	{
135 	  NGM_CAR_COOKIE,
136 	  NGM_CAR_CLR_STATS,
137 	  "clrstats",
138 	  NULL,
139 	  NULL,
140 	},
141 	{
142 	  NGM_CAR_COOKIE,
143 	  NGM_CAR_GETCLR_STATS,
144 	  "getclrstats",
145 	  NULL,
146 	  &ng_car_bulkstats_type,
147 	},
148 
149 	{
150 	  NGM_CAR_COOKIE,
151 	  NGM_CAR_GET_CONF,
152 	  "getconf",
153 	  NULL,
154 	  &ng_car_bulkconf_type,
155 	},
156 	{
157 	  NGM_CAR_COOKIE,
158 	  NGM_CAR_SET_CONF,
159 	  "setconf",
160 	  &ng_car_bulkconf_type,
161 	  NULL,
162 	},
163 	{ 0 }
164 };
165 
166 /* Netgraph node type descriptor */
167 static struct ng_type ng_car_typestruct = {
168 	.version =	NG_ABI_VERSION,
169 	.name =		NG_CAR_NODE_TYPE,
170 	.constructor =	ng_car_constructor,
171 	.rcvmsg =	ng_car_rcvmsg,
172 	.shutdown =	ng_car_shutdown,
173 	.newhook =	ng_car_newhook,
174 	.rcvdata =	ng_car_rcvdata,
175 	.disconnect =	ng_car_disconnect,
176 	.cmdlist =	ng_car_cmdlist,
177 };
178 NETGRAPH_INIT(car, &ng_car_typestruct);
179 
180 /*
181  * Node constructor
182  */
183 static int
184 ng_car_constructor(node_p node)
185 {
186 	priv_p priv;
187 
188 	/* Initialize private descriptor. */
189 	priv = malloc(sizeof(*priv), M_NETGRAPH, M_NOWAIT | M_ZERO);
190 	if (priv == NULL)
191 		return (ENOMEM);
192 
193 	NG_NODE_SET_PRIVATE(node, priv);
194 	priv->node = node;
195 
196 	/*
197 	 * Arbitrary default values
198 	 */
199 
200 	priv->upper.hook = NULL;
201 	priv->upper.dest = NULL;
202 	priv->upper.tc = priv->upper.conf.cbs = NG_CAR_CBS_MIN;
203 	priv->upper.te = priv->upper.conf.ebs = NG_CAR_EBS_MIN;
204 	priv->upper.conf.cir = NG_CAR_CIR_DFLT;
205 	priv->upper.conf.green_action = NG_CAR_ACTION_FORWARD;
206 	priv->upper.conf.yellow_action = NG_CAR_ACTION_FORWARD;
207 	priv->upper.conf.red_action = NG_CAR_ACTION_DROP;
208 	priv->upper.conf.mode = 0;
209 	getbinuptime(&priv->upper.lastRefill);
210 	priv->upper.q_first = 0;
211 	priv->upper.q_last = 0;
212 	ng_callout_init(&priv->upper.q_callout);
213 	mtx_init(&priv->upper.q_mtx, "ng_car_u", NULL, MTX_DEF);
214 
215 	priv->lower.hook = NULL;
216 	priv->lower.dest = NULL;
217 	priv->lower.tc = priv->lower.conf.cbs = NG_CAR_CBS_MIN;
218 	priv->lower.te = priv->lower.conf.ebs = NG_CAR_EBS_MIN;
219 	priv->lower.conf.cir = NG_CAR_CIR_DFLT;
220 	priv->lower.conf.green_action = NG_CAR_ACTION_FORWARD;
221 	priv->lower.conf.yellow_action = NG_CAR_ACTION_FORWARD;
222 	priv->lower.conf.red_action = NG_CAR_ACTION_DROP;
223 	priv->lower.conf.mode = 0;
224 	priv->lower.lastRefill = priv->upper.lastRefill;
225 	priv->lower.q_first = 0;
226 	priv->lower.q_last = 0;
227 	ng_callout_init(&priv->lower.q_callout);
228 	mtx_init(&priv->lower.q_mtx, "ng_car_l", NULL, MTX_DEF);
229 
230 	return (0);
231 }
232 
233 /*
234  * Add a hook.
235  */
236 static int
237 ng_car_newhook(node_p node, hook_p hook, const char *name)
238 {
239 	const priv_p priv = NG_NODE_PRIVATE(node);
240 
241 	if (strcmp(name, NG_CAR_HOOK_LOWER) == 0) {
242 		priv->lower.hook = hook;
243 		priv->upper.dest = hook;
244 		bzero(&priv->lower.stats, sizeof(priv->lower.stats));
245 		NG_HOOK_SET_PRIVATE(hook, &priv->lower);
246 	} else if (strcmp(name, NG_CAR_HOOK_UPPER) == 0) {
247 		priv->upper.hook = hook;
248 		priv->lower.dest = hook;
249 		bzero(&priv->upper.stats, sizeof(priv->upper.stats));
250 		NG_HOOK_SET_PRIVATE(hook, &priv->upper);
251 	} else
252 		return (EINVAL);
253 	return(0);
254 }
255 
256 /*
257  * Data has arrived.
258  */
259 static int
260 ng_car_rcvdata(hook_p hook, item_p item )
261 {
262 	struct hookinfo *const hinfo = NG_HOOK_PRIVATE(hook);
263 	struct mbuf *m;
264 	int error = 0;
265 	u_int len;
266 
267 	/* If queue is not empty now then enqueue packet. */
268 	if (hinfo->q_first != hinfo->q_last) {
269 		ng_car_enqueue(hinfo, item);
270 		return (0);
271 	}
272 
273 	m = NGI_M(item);
274 
275 #define NG_CAR_PERFORM_MATCH_ACTION(a)			\
276 	do {						\
277 		switch (a) {				\
278 		case NG_CAR_ACTION_FORWARD:		\
279 			/* Do nothing. */		\
280 			break;				\
281 		case NG_CAR_ACTION_MARK:		\
282 			/* XXX find a way to mark packets (mbuf tag?) */ \
283 			++hinfo->stats.errors;		\
284 			break;				\
285 		case NG_CAR_ACTION_DROP:		\
286 		default:				\
287 			/* Drop packet and return. */	\
288 			NG_FREE_ITEM(item);		\
289 			++hinfo->stats.droped_pkts;	\
290 			return (0);			\
291 		}					\
292 	} while (0)
293 
294 	/* Packet is counted as 128 tokens for better resolution */
295 	if (hinfo->conf.opt & NG_CAR_COUNT_PACKETS) {
296 		len = 128;
297 	} else {
298 		len = m->m_pkthdr.len;
299 	}
300 
301 	/* Check commited token bucket. */
302 	if (hinfo->tc - len >= 0) {
303 		/* This packet is green. */
304 		++hinfo->stats.green_pkts;
305 		hinfo->tc -= len;
306 		NG_CAR_PERFORM_MATCH_ACTION(hinfo->conf.green_action);
307 	} else {
308 
309 		/* Refill only if not green without it. */
310 		ng_car_refillhook(hinfo);
311 
312 		 /* Check commited token bucket again after refill. */
313 		if (hinfo->tc - len >= 0) {
314 			/* This packet is green */
315 			++hinfo->stats.green_pkts;
316 			hinfo->tc -= len;
317 			NG_CAR_PERFORM_MATCH_ACTION(hinfo->conf.green_action);
318 
319 		/* If not green and mode is SHAPE, enqueue packet. */
320 		} else if (hinfo->conf.mode == NG_CAR_SHAPE) {
321 			ng_car_enqueue(hinfo, item);
322 			return (0);
323 
324 		/* If not green and mode is RED, calculate probability. */
325 		} else if (hinfo->conf.mode == NG_CAR_RED) {
326 			/* Is packet is bigger then extended burst? */
327 			if (len - (hinfo->tc - len) > hinfo->conf.ebs) {
328 				/* This packet is definitely red. */
329 				++hinfo->stats.red_pkts;
330 				hinfo->te = 0;
331 				NG_CAR_PERFORM_MATCH_ACTION(hinfo->conf.red_action);
332 
333 			/* Use token bucket to simulate RED-like drop
334 			   probability. */
335 			} else if (hinfo->te + (len - hinfo->tc) <
336 			    hinfo->conf.ebs) {
337 				/* This packet is yellow */
338 				++hinfo->stats.yellow_pkts;
339 				hinfo->te += len - hinfo->tc;
340 				/* Go to negative tokens. */
341 				hinfo->tc -= len;
342 				NG_CAR_PERFORM_MATCH_ACTION(hinfo->conf.yellow_action);
343 			} else {
344 				/* This packet is probaly red. */
345 				++hinfo->stats.red_pkts;
346 				hinfo->te = 0;
347 				NG_CAR_PERFORM_MATCH_ACTION(hinfo->conf.red_action);
348 			}
349 		/* If not green and mode is SINGLE/DOUBLE RATE. */
350 		} else {
351 			/* Check extended token bucket. */
352 			if (hinfo->te - len >= 0) {
353 				/* This packet is yellow */
354 				++hinfo->stats.yellow_pkts;
355 				hinfo->te -= len;
356 				NG_CAR_PERFORM_MATCH_ACTION(hinfo->conf.yellow_action);
357 			} else {
358 				/* This packet is red */
359 				++hinfo->stats.red_pkts;
360 				NG_CAR_PERFORM_MATCH_ACTION(hinfo->conf.red_action);
361 			}
362 		}
363 	}
364 
365 #undef NG_CAR_PERFORM_MATCH_ACTION
366 
367 	NG_FWD_ITEM_HOOK(error, item, hinfo->dest);
368 	if (error != 0)
369 		++hinfo->stats.errors;
370 	++hinfo->stats.passed_pkts;
371 
372 	return (error);
373 }
374 
375 /*
376  * Receive a control message.
377  */
378 static int
379 ng_car_rcvmsg(node_p node, item_p item, hook_p lasthook)
380 {
381 	const priv_p priv = NG_NODE_PRIVATE(node);
382 	struct ng_mesg *resp = NULL;
383 	int error = 0;
384 	struct ng_mesg *msg;
385 
386 	NGI_GET_MSG(item, msg);
387 	switch (msg->header.typecookie) {
388 	case NGM_CAR_COOKIE:
389 		switch (msg->header.cmd) {
390 		case NGM_CAR_GET_STATS:
391 		case NGM_CAR_GETCLR_STATS:
392 			{
393 				struct ng_car_bulkstats *bstats;
394 
395 				NG_MKRESPONSE(resp, msg,
396 					sizeof(*bstats), M_NOWAIT);
397 				if (resp == NULL) {
398 					error = ENOMEM;
399 					break;
400 				}
401 				bstats = (struct ng_car_bulkstats *)resp->data;
402 
403 				bcopy(&priv->upper.stats, &bstats->downstream,
404 				    sizeof(bstats->downstream));
405 				bcopy(&priv->lower.stats, &bstats->upstream,
406 				    sizeof(bstats->upstream));
407 			}
408 			if (msg->header.cmd == NGM_CAR_GET_STATS)
409 				break;
410 		case NGM_CAR_CLR_STATS:
411 			bzero(&priv->upper.stats,
412 				sizeof(priv->upper.stats));
413 			bzero(&priv->lower.stats,
414 				sizeof(priv->lower.stats));
415 			break;
416 		case NGM_CAR_GET_CONF:
417 			{
418 				struct ng_car_bulkconf *bconf;
419 
420 				NG_MKRESPONSE(resp, msg,
421 					sizeof(*bconf), M_NOWAIT);
422 				if (resp == NULL) {
423 					error = ENOMEM;
424 					break;
425 				}
426 				bconf = (struct ng_car_bulkconf *)resp->data;
427 
428 				bcopy(&priv->upper.conf, &bconf->downstream,
429 				    sizeof(bconf->downstream));
430 				bcopy(&priv->lower.conf, &bconf->upstream,
431 				    sizeof(bconf->upstream));
432 				/* Convert internal 1/(8*128) of pps into pps */
433 				if (bconf->downstream.opt & NG_CAR_COUNT_PACKETS) {
434 				    bconf->downstream.cir /= 1024;
435 				    bconf->downstream.pir /= 1024;
436 				    bconf->downstream.cbs /= 128;
437 				    bconf->downstream.ebs /= 128;
438 				}
439 				if (bconf->upstream.opt & NG_CAR_COUNT_PACKETS) {
440 				    bconf->upstream.cir /= 1024;
441 				    bconf->upstream.pir /= 1024;
442 				    bconf->upstream.cbs /= 128;
443 				    bconf->upstream.ebs /= 128;
444 				}
445 			}
446 			break;
447 		case NGM_CAR_SET_CONF:
448 			{
449 				struct ng_car_bulkconf *const bconf =
450 				(struct ng_car_bulkconf *)msg->data;
451 
452 				/* Check for invalid or illegal config. */
453 				if (msg->header.arglen != sizeof(*bconf)) {
454 					error = EINVAL;
455 					break;
456 				}
457 				/* Convert pps into internal 1/(8*128) of pps */
458 				if (bconf->downstream.opt & NG_CAR_COUNT_PACKETS) {
459 				    bconf->downstream.cir *= 1024;
460 				    bconf->downstream.pir *= 1024;
461 				    bconf->downstream.cbs *= 125;
462 				    bconf->downstream.ebs *= 125;
463 				}
464 				if (bconf->upstream.opt & NG_CAR_COUNT_PACKETS) {
465 				    bconf->upstream.cir *= 1024;
466 				    bconf->upstream.pir *= 1024;
467 				    bconf->upstream.cbs *= 125;
468 				    bconf->upstream.ebs *= 125;
469 				}
470 				if ((bconf->downstream.cir > 1000000000) ||
471 				    (bconf->downstream.pir > 1000000000) ||
472 				    (bconf->upstream.cir > 1000000000) ||
473 				    (bconf->upstream.pir > 1000000000) ||
474 				    (bconf->downstream.cbs == 0 &&
475 					bconf->downstream.ebs == 0) ||
476 				    (bconf->upstream.cbs == 0 &&
477 					bconf->upstream.ebs == 0))
478 				{
479 					error = EINVAL;
480 					break;
481 				}
482 				if ((bconf->upstream.mode == NG_CAR_SHAPE) &&
483 				    (bconf->upstream.cir == 0)) {
484 					error = EINVAL;
485 					break;
486 				}
487 				if ((bconf->downstream.mode == NG_CAR_SHAPE) &&
488 				    (bconf->downstream.cir == 0)) {
489 					error = EINVAL;
490 					break;
491 				}
492 
493 				/* Copy downstream config. */
494 				bcopy(&bconf->downstream, &priv->upper.conf,
495 				    sizeof(priv->upper.conf));
496     				priv->upper.tc = priv->upper.conf.cbs;
497 				if (priv->upper.conf.mode == NG_CAR_RED ||
498 				    priv->upper.conf.mode == NG_CAR_SHAPE) {
499 					priv->upper.te = 0;
500 				} else {
501 					priv->upper.te = priv->upper.conf.ebs;
502 				}
503 
504 				/* Copy upstream config. */
505 				bcopy(&bconf->upstream, &priv->lower.conf,
506 				    sizeof(priv->lower.conf));
507     				priv->lower.tc = priv->lower.conf.cbs;
508 				if (priv->lower.conf.mode == NG_CAR_RED ||
509 				    priv->lower.conf.mode == NG_CAR_SHAPE) {
510 					priv->lower.te = 0;
511 				} else {
512 					priv->lower.te = priv->lower.conf.ebs;
513 				}
514 			}
515 			break;
516 		default:
517 			error = EINVAL;
518 			break;
519 		}
520 		break;
521 	default:
522 		error = EINVAL;
523 		break;
524 	}
525 	NG_RESPOND_MSG(error, node, item, resp);
526 	NG_FREE_MSG(msg);
527 	return (error);
528 }
529 
530 /*
531  * Do local shutdown processing.
532  */
533 static int
534 ng_car_shutdown(node_p node)
535 {
536 	const priv_p priv = NG_NODE_PRIVATE(node);
537 
538 	ng_uncallout(&priv->upper.q_callout, node);
539 	ng_uncallout(&priv->lower.q_callout, node);
540 	mtx_destroy(&priv->upper.q_mtx);
541 	mtx_destroy(&priv->lower.q_mtx);
542 	NG_NODE_UNREF(priv->node);
543 	free(priv, M_NETGRAPH);
544 	return (0);
545 }
546 
547 /*
548  * Hook disconnection.
549  *
550  * For this type, removal of the last link destroys the node.
551  */
552 static int
553 ng_car_disconnect(hook_p hook)
554 {
555 	struct hookinfo *const hinfo = NG_HOOK_PRIVATE(hook);
556 	const node_p node = NG_HOOK_NODE(hook);
557 	const priv_p priv = NG_NODE_PRIVATE(node);
558 
559 	if (hinfo) {
560 		/* Purge queue if not empty. */
561 		while (hinfo->q_first != hinfo->q_last) {
562 			NG_FREE_M(hinfo->q[hinfo->q_first]);
563 			hinfo->q_first++;
564 			if (hinfo->q_first >= NG_CAR_QUEUE_SIZE)
565 		    		hinfo->q_first = 0;
566 		}
567 		/* Remove hook refs. */
568 		if (hinfo->hook == priv->upper.hook)
569 			priv->lower.dest = NULL;
570 		else
571 			priv->upper.dest = NULL;
572 		hinfo->hook = NULL;
573 	}
574 	/* Already shutting down? */
575 	if ((NG_NODE_NUMHOOKS(NG_HOOK_NODE(hook)) == 0)
576 	    && (NG_NODE_IS_VALID(NG_HOOK_NODE(hook))))
577 		ng_rmnode_self(NG_HOOK_NODE(hook));
578 	return (0);
579 }
580 
581 /*
582  * Hook's token buckets refillment.
583  */
584 static void
585 ng_car_refillhook(struct hookinfo *h)
586 {
587 	struct bintime newt, deltat;
588 	unsigned int deltat_us;
589 
590 	/* Get current time. */
591 	getbinuptime(&newt);
592 
593 	/* Get time delta since last refill. */
594 	deltat = newt;
595 	bintime_sub(&deltat, &h->lastRefill);
596 
597 	/* Time must go forward. */
598 	if (deltat.sec < 0) {
599 	    h->lastRefill = newt;
600 	    return;
601 	}
602 
603 	/* But not too far forward. */
604 	if (deltat.sec >= 1000) {
605 	    deltat_us = (1000 << 20);
606 	} else {
607 	    /* convert bintime to the 1/(2^20) of sec */
608 	    deltat_us = (deltat.sec << 20) + (deltat.frac >> 44);
609 	}
610 
611 	if (h->conf.mode == NG_CAR_SINGLE_RATE) {
612 		int64_t	delta;
613 		/* Refill commited token bucket. */
614 		h->tc += (h->conf.cir * deltat_us) >> 23;
615 		delta = h->tc - h->conf.cbs;
616 		if (delta > 0) {
617 			h->tc = h->conf.cbs;
618 
619 			/* Refill exceeded token bucket. */
620 			h->te += delta;
621 			if (h->te > ((int64_t)h->conf.ebs))
622 				h->te = h->conf.ebs;
623 		}
624 
625 	} else if (h->conf.mode == NG_CAR_DOUBLE_RATE) {
626 		/* Refill commited token bucket. */
627 		h->tc += (h->conf.cir * deltat_us) >> 23;
628 		if (h->tc > ((int64_t)h->conf.cbs))
629 			h->tc = h->conf.cbs;
630 
631 		/* Refill peak token bucket. */
632 		h->te += (h->conf.pir * deltat_us) >> 23;
633 		if (h->te > ((int64_t)h->conf.ebs))
634 			h->te = h->conf.ebs;
635 
636 	} else { /* RED or SHAPE mode. */
637 		/* Refill commited token bucket. */
638 		h->tc += (h->conf.cir * deltat_us) >> 23;
639 		if (h->tc > ((int64_t)h->conf.cbs))
640 			h->tc = h->conf.cbs;
641 	}
642 
643 	/* Remember this moment. */
644 	h->lastRefill = newt;
645 }
646 
647 /*
648  * Schedule callout when we will have required tokens.
649  */
650 static void
651 ng_car_schedule(struct hookinfo *hinfo)
652 {
653 	int 	delay;
654 
655 	delay = (-(hinfo->tc)) * hz * 8 / hinfo->conf.cir + 1;
656 
657 	ng_callout(&hinfo->q_callout, NG_HOOK_NODE(hinfo->hook), hinfo->hook,
658 	    delay, &ng_car_q_event, NULL, 0);
659 }
660 
661 /*
662  * Queue processing callout handler.
663  */
664 void
665 ng_car_q_event(node_p node, hook_p hook, void *arg, int arg2)
666 {
667 	struct hookinfo	*hinfo = NG_HOOK_PRIVATE(hook);
668 	struct mbuf 	*m;
669 	int		error;
670 
671 	/* Refill tokens for time we have slept. */
672 	ng_car_refillhook(hinfo);
673 
674 	/* If we have some tokens */
675 	while (hinfo->tc >= 0) {
676 
677 		/* Send packet. */
678 		m = hinfo->q[hinfo->q_first];
679 		NG_SEND_DATA_ONLY(error, hinfo->dest, m);
680 		if (error != 0)
681 			++hinfo->stats.errors;
682 		++hinfo->stats.passed_pkts;
683 
684 		/* Get next one. */
685 		hinfo->q_first++;
686 		if (hinfo->q_first >= NG_CAR_QUEUE_SIZE)
687 			hinfo->q_first = 0;
688 
689 		/* Stop if none left. */
690 		if (hinfo->q_first == hinfo->q_last)
691 			break;
692 
693 		/* If we have more packet, try it. */
694 		m = hinfo->q[hinfo->q_first];
695 		if (hinfo->conf.opt & NG_CAR_COUNT_PACKETS) {
696 			hinfo->tc -= 128;
697 		} else {
698 			hinfo->tc -= m->m_pkthdr.len;
699 		}
700 	}
701 
702 	/* If something left */
703 	if (hinfo->q_first != hinfo->q_last)
704 		/* Schedule queue processing. */
705 		ng_car_schedule(hinfo);
706 }
707 
708 /*
709  * Enqueue packet.
710  */
711 static void
712 ng_car_enqueue(struct hookinfo *hinfo, item_p item)
713 {
714 	struct mbuf 	*m;
715 	int		len;
716 
717 	NGI_GET_M(item, m);
718 	NG_FREE_ITEM(item);
719 
720 	/* Lock queue mutex. */
721 	mtx_lock(&hinfo->q_mtx);
722 
723 	/* Calculate used queue length. */
724 	len = hinfo->q_last - hinfo->q_first;
725 	if (len < 0)
726 		len += NG_CAR_QUEUE_SIZE;
727 
728 	/* If queue is overflowed or we have no RED tokens. */
729 	if ((len >= (NG_CAR_QUEUE_SIZE - 1)) ||
730 	    (hinfo->te + len >= NG_CAR_QUEUE_SIZE)) {
731 		/* Drop packet. */
732 		++hinfo->stats.red_pkts;
733 		++hinfo->stats.droped_pkts;
734 		NG_FREE_M(m);
735 
736 		hinfo->te = 0;
737 	} else {
738 		/* This packet is yellow. */
739 		++hinfo->stats.yellow_pkts;
740 
741 		/* Enqueue packet. */
742 		hinfo->q[hinfo->q_last] = m;
743 		hinfo->q_last++;
744 		if (hinfo->q_last >= NG_CAR_QUEUE_SIZE)
745 			hinfo->q_last = 0;
746 
747 		/* Use RED tokens. */
748 		if (len > NG_CAR_QUEUE_MIN_TH)
749 			hinfo->te += len - NG_CAR_QUEUE_MIN_TH;
750 
751 		/* If this is a first packet in the queue. */
752 		if (len == 0) {
753 			if (hinfo->conf.opt & NG_CAR_COUNT_PACKETS) {
754 				hinfo->tc -= 128;
755 			} else {
756 				hinfo->tc -= m->m_pkthdr.len;
757 			}
758 
759 			/* Schedule queue processing. */
760 			ng_car_schedule(hinfo);
761 		}
762 	}
763 
764 	/* Unlock queue mutex. */
765 	mtx_unlock(&hinfo->q_mtx);
766 }
767