/*
 * q_netem.c		NETEM.
 *
 *		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@osdl.org>
 *
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <syslog.h>
#include <fcntl.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <string.h>
#include <errno.h>

#include "utils.h"
#include "tc_util.h"
#include "tc_common.h"

static void explain(void)
{
	fprintf(stderr, 
"Usage: ... netem [ limit PACKETS ] \n" \
"		  [ delay TIME [ JITTER [CORRELATION]]]\n" \
"                 [ drop PERCENT [CORRELATION]] \n" \
"                 [ duplicate PERCENT [CORRELATION]]\n" \
"		  [ distribution {uniform|normal|pareto|paretonormal} ]\n" \
"                 [ gap PACKETS ]\n");
}

static void explain1(const char *arg)
{
	fprintf(stderr, "Illegal \"%s\"\n", arg);
}

#define usage() return(-1)

static int get_distribution(const char *type, __s16 *data, int limit)
{
	FILE *f;
	int n;
	char *p, *endp, buf[256];

	snprintf(buf, 256, "/usr/lib/tc/%s.dist", type);
	f = fopen(buf, "r");
	if (!f) {
		fprintf(stderr, "No distribution data for %s (%s: %s)\n", 
			type, buf, strerror(errno));
		return -1;
	}
	
	n = 0;
	while (fgets(buf, sizeof(buf), f) != NULL) {
		if (*buf == '#')
			continue;

		for (p = buf; *p && n < limit; p = endp) {
			long x = strtol(p, &endp, 0);
			if (endp == p)
				break;	/* no more digits */
			data[n++] = x;
		}
	}
	fclose(f);

	if (n > limit) {
		fprintf(stderr, "Too much distribution data for %s\n", type);
		return -1;
	}

	return n;
}

static int isnumber(const char *arg) 
{
	char *p;
	(void) strtod(arg, &p);
	return (p != arg);
}

#define NEXT_IS_NUMBER() (NEXT_ARG_OK() && isnumber(argv[1]))

/* Adjust for the fact that psched_ticks aren't always usecs 
   (based on kernel PSCHED_CLOCK configuration */
static int get_ticks(__u32 *ticks, const char *str)
{
	unsigned t;

	if(get_usecs(&t, str))
		return -1;
	
	*ticks = tc_core_usec2tick(t);
	return 0;
}

static char *sprint_ticks(__u32 ticks, char *buf)
{
	return sprint_usecs(tc_core_tick2usec(ticks), buf);
}


static int netem_parse_opt(struct qdisc_util *qu, int argc, char **argv, 
			   struct nlmsghdr *n)
{
#define REQ_DIST_SIZE (TCA_BUF_MAX/sizeof(__s16))
	struct {
		struct tc_netem_qopt opt;
		__s16 dbuf[REQ_DIST_SIZE];
	} req;
	int size = sizeof(struct tc_netem_qopt);

	memset(&req.opt, 0, sizeof(req.opt));
	req.opt.limit = 1000;

	while (argc > 0) {
		if (matches(*argv, "limit") == 0) {
			NEXT_ARG();
			if (get_size(&req.opt.limit, *argv)) {
				explain1("limit");
				return -1;
			}
		} else if (matches(*argv, "latency") == 0 ||
			   matches(*argv, "delay") == 0) {
			NEXT_ARG();
			if (get_ticks(&req.opt.latency, *argv)) {
				explain1("latency");
				return -1;
			}

			if (NEXT_IS_NUMBER()) {
				NEXT_ARG();
				if (get_ticks(&req.opt.jitter, *argv)) {
					explain1("latency");
					return -1;
				}

				if (NEXT_IS_NUMBER()) {
					NEXT_ARG();
					if (get_percent(&req.opt.delay_corr, 
							*argv)) {
						explain1("latency");
						return -1;
					}
				}
			}
		} else if (matches(*argv, "loss") == 0 ||
			   matches(*argv, "drop") == 0) {
			NEXT_ARG();
			if (get_percent(&req.opt.loss, *argv)) {
				explain1("loss");
				return -1;
			}
			if (NEXT_IS_NUMBER()) {
				NEXT_ARG();
				if (get_percent(&req.opt.loss_corr, *argv)) {
					explain1("loss");
					return -1;
				}
			}
		} else if (matches(*argv, "gap") == 0) {
			NEXT_ARG();
			if (get_u32(&req.opt.gap, *argv, 0)) {
				explain1("gap");
				return -1;
			}
		} else if (matches(*argv, "duplicate") == 0) {
			NEXT_ARG();
			if (get_percent(&req.opt.duplicate, *argv)) {
				explain1("duplicate");
				return -1;
			}
			if (NEXT_IS_NUMBER()) {
				NEXT_ARG();
				if (get_percent(&req.opt.dup_corr, *argv)) {
					explain1("duplicate");
					return -1;
				}
			}
		} else if (matches(*argv, "distribution") == 0) {
			int count;
			NEXT_ARG();
			count = get_distribution(*argv, req.opt.delay_dist,
						 REQ_DIST_SIZE);
			if (count < 0) {
				explain1("distribution");
				return -1;
			}
			size = sizeof(struct tc_netem_qopt) 
				+ count * sizeof(req.opt.delay_dist[0]);
		} else if (strcmp(*argv, "help") == 0) {
			explain();
			return -1;
		} else {
			fprintf(stderr, "What is \"%s\"?\n", *argv);
			explain();
			return -1;
		}
		argc--; argv++;
	}

	if (addattr_l(n, TCA_BUF_MAX, TCA_OPTIONS, &req, size)) {
		fprintf(stderr, "netem: options encoding problem\n");
		return -1;
	}

	return 0;
}

static int netem_print_opt(struct qdisc_util *qu, FILE *f, struct rtattr *opt)
{
	struct tc_netem_qopt *qopt;
	SPRINT_BUF(b1);

	if (opt == NULL)
		return 0;

	if (RTA_PAYLOAD(opt) < sizeof(*qopt)) {
		fprintf(stderr, "netem response too short\n");
		return -1;
	}

	qopt = RTA_DATA(opt);

	fprintf(f, "limit %d", qopt->limit);

	if (qopt->latency) {
		fprintf(f, " delay %s", sprint_ticks(qopt->latency, b1));

		if (qopt->jitter) {
			fprintf(f, "  %s", sprint_ticks(qopt->jitter, b1));
			if (qopt->delay_corr)
				fprintf(f, " %s", sprint_percent(qopt->delay_corr, b1));
		}
	}

	if (qopt->loss) {
		fprintf(f, " loss %s",
			sprint_percent(qopt->loss, b1));
		if (qopt->loss_corr)
			fprintf(f, " %s", sprint_percent(qopt->loss_corr, b1));
	}

	if (qopt->duplicate) {
		fprintf(f, " duplicate %s",
			sprint_percent(qopt->duplicate, b1));
		if (qopt->dup_corr)
			fprintf(f, " %s", sprint_percent(qopt->dup_corr, b1));
	}

	if (qopt->gap)
		fprintf(f, " gap %lu", (unsigned long)qopt->gap);

	return 0;
}

static int netem_print_xstats(struct qdisc_util *qu, FILE *f, struct rtattr *xstats)
{
	return 0;
}

struct qdisc_util netem_util = {
	.id	   	= "netem",
	.parse_qopt	= netem_parse_opt,
	.print_qopt	= netem_print_opt,
	.print_xstats	= netem_print_xstats,
};