/*

 * q_choke.c		CHOKE.

 *

 *		This program 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.

 *

 * Authors:	Stephen Hemminger <shemminger@vyatta.com>

 */

#include <stdio.h>

#include <stdlib.h>

#include <unistd.h>

#include <fcntl.h>

#include <sys/socket.h>

#include <netinet/in.h>

#include <arpa/inet.h>

#include <string.h>

#include <math.h>

#include "utils.h"

#include "tc_util.h"

#include "tc_red.h"

static void explain(void)

{

	fprintf(stderr,

		"Usage: ... choke limit PACKETS bandwidth KBPS [ecn]\n"

		"		 [ min PACKETS ] [ max PACKETS ] [ burst PACKETS ]\n");

}

static int choke_parse_opt(struct qdisc_util *qu, int argc, char **argv,

			   struct nlmsghdr *n, const char *dev)

{

	struct tc_red_qopt opt = {};

	unsigned int burst = 0;

	unsigned int avpkt = 1000;

	double probability = 0.02;

	unsigned int rate = 0;

	int ecn_ok = 0;

	int wlog;

	__u8 sbuf[256];

	__u32 max_P;

	struct rtattr *tail;

	while (argc > 0) {

		if (strcmp(*argv, "limit") == 0) {

			NEXT_ARG();

			if (get_unsigned(&opt.limit, *argv, 0)) {

				fprintf(stderr, "Illegal \"limit\"\n");

				return -1;

			}

		} else if (strcmp(*argv, "bandwidth") == 0) {

			NEXT_ARG();

			if (strchr(*argv, '%')) {

				if (get_percent_rate(&rate, *argv, dev)) {

					fprintf(stderr, "Illegal \"bandwidth\"\n");

					return -1;

				}

			} else if (get_rate(&rate, *argv)) {

				fprintf(stderr, "Illegal \"bandwidth\"\n");

				return -1;

			}

		} else if (strcmp(*argv, "ecn") == 0) {

			ecn_ok = 1;

		} else if (strcmp(*argv, "min") == 0) {

			NEXT_ARG();

			if (get_unsigned(&opt.qth_min, *argv, 0)) {

				fprintf(stderr, "Illegal \"min\"\n");

				return -1;

			}

		} else if (strcmp(*argv, "max") == 0) {

			NEXT_ARG();

			if (get_unsigned(&opt.qth_max, *argv, 0)) {

				fprintf(stderr, "Illegal \"max\"\n");

				return -1;

			}

		} else if (strcmp(*argv, "burst") == 0) {

			NEXT_ARG();

			if (get_unsigned(&burst, *argv, 0)) {

				fprintf(stderr, "Illegal \"burst\"\n");

				return -1;

			}

		} else if (strcmp(*argv, "avpkt") == 0) {

			NEXT_ARG();

			if (get_size(&avpkt, *argv)) {

				fprintf(stderr, "Illegal \"avpkt\"\n");

				return -1;

			}

		} else if (strcmp(*argv, "probability") == 0) {

			NEXT_ARG();

			if (sscanf(*argv, "%lg", &probability) != 1) {

				fprintf(stderr, "Illegal \"probability\"\n");

				return -1;

			}

		} else if (strcmp(*argv, "help") == 0) {

			explain();

			return -1;

		} else {

			fprintf(stderr, "What is \"%s\"?\n", *argv);

			explain();

			return -1;

		}

		argc--; argv++;

	}

	if (!rate || !opt.limit) {

		fprintf(stderr, "Required parameter (bandwidth, limit) is missing\n");

		return -1;

	}

	/* Compute default min/max thresholds based on

	   Sally Floyd's recommendations:

	   http://www.icir.org/floyd/REDparameters.txt

	*/

	if (!opt.qth_max)

		opt.qth_max = opt.limit / 4;

	if (!opt.qth_min)

		opt.qth_min = opt.qth_max / 3;

	if (!burst)

		burst = (2 * opt.qth_min + opt.qth_max) / 3;

	if (opt.qth_max > opt.limit) {

		fprintf(stderr, "\"max\" is larger than \"limit\"\n");

		return -1;

	}

	if (opt.qth_min >= opt.qth_max) {

		fprintf(stderr, "\"min\" is not smaller than \"max\"\n");

		return -1;

	}

	wlog = tc_red_eval_ewma(opt.qth_min*avpkt, burst, avpkt);

	if (wlog < 0) {

		fprintf(stderr, "CHOKE: failed to calculate EWMA constant.\n");

		return -1;

	}

	if (wlog >= 10)

		fprintf(stderr, "CHOKE: WARNING. Burst %d seems to be too large.\n", burst);

	opt.Wlog = wlog;

	wlog = tc_red_eval_P(opt.qth_min*avpkt, opt.qth_max*avpkt, probability);

	if (wlog < 0) {

		fprintf(stderr, "CHOKE: failed to calculate probability.\n");

		return -1;

	}

	opt.Plog = wlog;

	wlog = tc_red_eval_idle_damping(opt.Wlog, avpkt, rate, sbuf);

	if (wlog < 0) {

		fprintf(stderr, "CHOKE: failed to calculate idle damping table.\n");

		return -1;

	}

	opt.Scell_log = wlog;

	if (ecn_ok)

		opt.flags |= TC_RED_ECN;

	tail = addattr_nest(n, 1024, TCA_OPTIONS);

	addattr_l(n, 1024, TCA_CHOKE_PARMS, &opt, sizeof(opt));

	addattr_l(n, 1024, TCA_CHOKE_STAB, sbuf, 256);

	max_P = probability * pow(2, 32);

	addattr_l(n, 1024, TCA_CHOKE_MAX_P, &max_P, sizeof(max_P));

	addattr_nest_end(n, tail);

	return 0;

}

static int choke_print_opt(struct qdisc_util *qu, FILE *f, struct rtattr *opt)

{

	struct rtattr *tb[TCA_CHOKE_MAX+1];

	const struct tc_red_qopt *qopt;

	__u32 max_P = 0;

	if (opt == NULL)

		return 0;

	parse_rtattr_nested(tb, TCA_CHOKE_MAX, opt);

	if (tb[TCA_CHOKE_PARMS] == NULL)

		return -1;

	qopt = RTA_DATA(tb[TCA_CHOKE_PARMS]);

	if (RTA_PAYLOAD(tb[TCA_CHOKE_PARMS])  < sizeof(*qopt))

		return -1;

	if (tb[TCA_CHOKE_MAX_P] &&

	    RTA_PAYLOAD(tb[TCA_CHOKE_MAX_P]) >= sizeof(__u32))

		max_P = rta_getattr_u32(tb[TCA_CHOKE_MAX_P]);

	fprintf(f, "limit %up min %up max %up ",

		qopt->limit, qopt->qth_min, qopt->qth_max);

	tc_red_print_flags(qopt->flags);

	if (show_details) {

		fprintf(f, "ewma %u ", qopt->Wlog);

		if (max_P)

			fprintf(f, "probability %g ", max_P / pow(2, 32));

		else

			fprintf(f, "Plog %u ", qopt->Plog);

		fprintf(f, "Scell_log %u", qopt->Scell_log);

	}

	return 0;

}

static int choke_print_xstats(struct qdisc_util *qu, FILE *f,

			      struct rtattr *xstats)

{

	struct tc_choke_xstats *st;

	if (xstats == NULL)

		return 0;

	if (RTA_PAYLOAD(xstats) < sizeof(*st))

		return -1;

	st = RTA_DATA(xstats);

	fprintf(f, "  marked %u early %u pdrop %u other %u matched %u",

		st->marked, st->early, st->pdrop, st->other, st->matched);

	return 0;

}

struct qdisc_util choke_qdisc_util = {

	.id		= "choke",

	.parse_qopt	= choke_parse_opt,

	.print_qopt	= choke_print_opt,

	.print_xstats	= choke_print_xstats,

};