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      1 /*
      2  * Copyright (c) 2009-2012 Niels Provos and Nick Mathewson
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions
      6  * are met:
      7  * 1. Redistributions of source code must retain the above copyright
      8  *    notice, this list of conditions and the following disclaimer.
      9  * 2. Redistributions in binary form must reproduce the above copyright
     10  *    notice, this list of conditions and the following disclaimer in the
     11  *    documentation and/or other materials provided with the distribution.
     12  * 3. The name of the author may not be used to endorse or promote products
     13  *    derived from this software without specific prior written permission.
     14  *
     15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     25  */
     26 #include "../util-internal.h"
     27 
     28 #include <stdio.h>
     29 #include <stdlib.h>
     30 #include <string.h>
     31 #include <assert.h>
     32 #include <math.h>
     33 
     34 #ifdef _WIN32
     35 #include <winsock2.h>
     36 #include <ws2tcpip.h>
     37 #else
     38 #include <sys/socket.h>
     39 #include <netinet/in.h>
     40 # ifdef _XOPEN_SOURCE_EXTENDED
     41 #  include <arpa/inet.h>
     42 # endif
     43 #endif
     44 #include <signal.h>
     45 
     46 #include "event2/bufferevent.h"
     47 #include "event2/buffer.h"
     48 #include "event2/event.h"
     49 #include "event2/util.h"
     50 #include "event2/listener.h"
     51 #include "event2/thread.h"
     52 
     53 static struct evutil_weakrand_state weakrand_state;
     54 
     55 static int cfg_verbose = 0;
     56 static int cfg_help = 0;
     57 
     58 static int cfg_n_connections = 30;
     59 static int cfg_duration = 5;
     60 static int cfg_connlimit = 0;
     61 static int cfg_grouplimit = 0;
     62 static int cfg_tick_msec = 1000;
     63 static int cfg_min_share = -1;
     64 static int cfg_group_drain = 0;
     65 
     66 static int cfg_connlimit_tolerance = -1;
     67 static int cfg_grouplimit_tolerance = -1;
     68 static int cfg_stddev_tolerance = -1;
     69 
     70 #ifdef _WIN32
     71 static int cfg_enable_iocp = 0;
     72 #endif
     73 
     74 static struct timeval cfg_tick = { 0, 500*1000 };
     75 
     76 static struct ev_token_bucket_cfg *conn_bucket_cfg = NULL;
     77 static struct ev_token_bucket_cfg *group_bucket_cfg = NULL;
     78 struct bufferevent_rate_limit_group *ratelim_group = NULL;
     79 static double seconds_per_tick = 0.0;
     80 
     81 struct client_state {
     82 	size_t queued;
     83 	ev_uint64_t received;
     84 
     85 };
     86 static const struct timeval *ms100_common=NULL;
     87 
     88 /* info from check_bucket_levels_cb */
     89 static int total_n_bev_checks = 0;
     90 static ev_int64_t total_rbucket_level=0;
     91 static ev_int64_t total_wbucket_level=0;
     92 static ev_int64_t total_max_to_read=0;
     93 static ev_int64_t total_max_to_write=0;
     94 static ev_int64_t max_bucket_level=EV_INT64_MIN;
     95 static ev_int64_t min_bucket_level=EV_INT64_MAX;
     96 
     97 /* from check_group_bucket_levels_cb */
     98 static int total_n_group_bev_checks = 0;
     99 static ev_int64_t total_group_rbucket_level = 0;
    100 static ev_int64_t total_group_wbucket_level = 0;
    101 
    102 static int n_echo_conns_open = 0;
    103 
    104 /* Info on the open connections */
    105 struct bufferevent **bevs;
    106 struct client_state *states;
    107 struct bufferevent_rate_limit_group *group = NULL;
    108 
    109 static void check_bucket_levels_cb(evutil_socket_t fd, short events, void *arg);
    110 
    111 static void
    112 loud_writecb(struct bufferevent *bev, void *ctx)
    113 {
    114 	struct client_state *cs = ctx;
    115 	struct evbuffer *output = bufferevent_get_output(bev);
    116 	char buf[1024];
    117 	int r = evutil_weakrand_(&weakrand_state);
    118 	memset(buf, r, sizeof(buf));
    119 	while (evbuffer_get_length(output) < 8192) {
    120 		evbuffer_add(output, buf, sizeof(buf));
    121 		cs->queued += sizeof(buf);
    122 	}
    123 }
    124 
    125 static void
    126 discard_readcb(struct bufferevent *bev, void *ctx)
    127 {
    128 	struct client_state *cs = ctx;
    129 	struct evbuffer *input = bufferevent_get_input(bev);
    130 	size_t len = evbuffer_get_length(input);
    131 	evbuffer_drain(input, len);
    132 	cs->received += len;
    133 }
    134 
    135 static void
    136 write_on_connectedcb(struct bufferevent *bev, short what, void *ctx)
    137 {
    138 	if (what & BEV_EVENT_CONNECTED) {
    139 		loud_writecb(bev, ctx);
    140 		/* XXXX this shouldn't be needed. */
    141 		bufferevent_enable(bev, EV_READ|EV_WRITE);
    142 	}
    143 }
    144 
    145 static void
    146 echo_readcb(struct bufferevent *bev, void *ctx)
    147 {
    148 	struct evbuffer *input = bufferevent_get_input(bev);
    149 	struct evbuffer *output = bufferevent_get_output(bev);
    150 
    151 	evbuffer_add_buffer(output, input);
    152 	if (evbuffer_get_length(output) > 1024000)
    153 		bufferevent_disable(bev, EV_READ);
    154 }
    155 
    156 static void
    157 echo_writecb(struct bufferevent *bev, void *ctx)
    158 {
    159 	struct evbuffer *output = bufferevent_get_output(bev);
    160 	if (evbuffer_get_length(output) < 512000)
    161 		bufferevent_enable(bev, EV_READ);
    162 }
    163 
    164 static void
    165 echo_eventcb(struct bufferevent *bev, short what, void *ctx)
    166 {
    167 	if (what & (BEV_EVENT_EOF|BEV_EVENT_ERROR)) {
    168 		--n_echo_conns_open;
    169 		bufferevent_free(bev);
    170 	}
    171 }
    172 
    173 static void
    174 echo_listenercb(struct evconnlistener *listener, evutil_socket_t newsock,
    175     struct sockaddr *sourceaddr, int socklen, void *ctx)
    176 {
    177 	struct event_base *base = ctx;
    178 	int flags = BEV_OPT_CLOSE_ON_FREE|BEV_OPT_THREADSAFE;
    179 	struct bufferevent *bev;
    180 
    181 	bev = bufferevent_socket_new(base, newsock, flags);
    182 	bufferevent_setcb(bev, echo_readcb, echo_writecb, echo_eventcb, NULL);
    183 	if (conn_bucket_cfg) {
    184 		struct event *check_event =
    185 		    event_new(base, -1, EV_PERSIST, check_bucket_levels_cb, bev);
    186 		bufferevent_set_rate_limit(bev, conn_bucket_cfg);
    187 
    188 		assert(bufferevent_get_token_bucket_cfg(bev) != NULL);
    189 		event_add(check_event, ms100_common);
    190 	}
    191 	if (ratelim_group)
    192 		bufferevent_add_to_rate_limit_group(bev, ratelim_group);
    193 	++n_echo_conns_open;
    194 	bufferevent_enable(bev, EV_READ|EV_WRITE);
    195 }
    196 
    197 /* Called periodically to check up on how full the buckets are */
    198 static void
    199 check_bucket_levels_cb(evutil_socket_t fd, short events, void *arg)
    200 {
    201 	struct bufferevent *bev = arg;
    202 
    203 	ev_ssize_t r = bufferevent_get_read_limit(bev);
    204 	ev_ssize_t w = bufferevent_get_write_limit(bev);
    205 	ev_ssize_t rm = bufferevent_get_max_to_read(bev);
    206 	ev_ssize_t wm = bufferevent_get_max_to_write(bev);
    207 	/* XXXX check that no value is above the cofigured burst
    208 	 * limit */
    209 	total_rbucket_level += r;
    210 	total_wbucket_level += w;
    211 	total_max_to_read += rm;
    212 	total_max_to_write += wm;
    213 #define B(x) \
    214 	if ((x) > max_bucket_level)		\
    215 		max_bucket_level = (x);		\
    216 	if ((x) < min_bucket_level)		\
    217 		min_bucket_level = (x)
    218 	B(r);
    219 	B(w);
    220 #undef B
    221 
    222 	total_n_bev_checks++;
    223 	if (total_n_bev_checks >= .8 * ((double)cfg_duration / cfg_tick_msec) * cfg_n_connections) {
    224 		event_free(event_base_get_running_event(bufferevent_get_base(bev)));
    225 	}
    226 }
    227 
    228 static void
    229 check_group_bucket_levels_cb(evutil_socket_t fd, short events, void *arg)
    230 {
    231 	if (ratelim_group) {
    232 		ev_ssize_t r = bufferevent_rate_limit_group_get_read_limit(ratelim_group);
    233 		ev_ssize_t w = bufferevent_rate_limit_group_get_write_limit(ratelim_group);
    234 		total_group_rbucket_level += r;
    235 		total_group_wbucket_level += w;
    236 	}
    237 	++total_n_group_bev_checks;
    238 }
    239 
    240 static void
    241 group_drain_cb(evutil_socket_t fd, short events, void *arg)
    242 {
    243 	bufferevent_rate_limit_group_decrement_read(ratelim_group, cfg_group_drain);
    244 	bufferevent_rate_limit_group_decrement_write(ratelim_group, cfg_group_drain);
    245 }
    246 
    247 static int
    248 test_ratelimiting(void)
    249 {
    250 	struct event_base *base;
    251 	struct sockaddr_in sin;
    252 	struct evconnlistener *listener;
    253 
    254 	struct sockaddr_storage ss;
    255 	ev_socklen_t slen;
    256 
    257 	int i;
    258 
    259 	struct timeval tv;
    260 
    261 	ev_uint64_t total_received;
    262 	double total_sq_persec, total_persec;
    263 	double variance;
    264 	double expected_total_persec = -1.0, expected_avg_persec = -1.0;
    265 	int ok = 1;
    266 	struct event_config *base_cfg;
    267 	struct event *periodic_level_check;
    268 	struct event *group_drain_event=NULL;
    269 
    270 	memset(&sin, 0, sizeof(sin));
    271 	sin.sin_family = AF_INET;
    272 	sin.sin_addr.s_addr = htonl(0x7f000001); /* 127.0.0.1 */
    273 	sin.sin_port = 0; /* unspecified port */
    274 
    275 	if (0)
    276 		event_enable_debug_mode();
    277 
    278 	base_cfg = event_config_new();
    279 
    280 #ifdef _WIN32
    281 	if (cfg_enable_iocp) {
    282 #ifdef EVTHREAD_USE_WINDOWS_THREADS_IMPLEMENTED
    283 		evthread_use_windows_threads();
    284 #endif
    285 		event_config_set_flag(base_cfg, EVENT_BASE_FLAG_STARTUP_IOCP);
    286 	}
    287 #endif
    288 
    289 	base = event_base_new_with_config(base_cfg);
    290 	event_config_free(base_cfg);
    291 	if (! base) {
    292 		fprintf(stderr, "Couldn't create event_base");
    293 		return 1;
    294 	}
    295 
    296 	listener = evconnlistener_new_bind(base, echo_listenercb, base,
    297 	    LEV_OPT_CLOSE_ON_FREE|LEV_OPT_REUSEABLE, -1,
    298 	    (struct sockaddr *)&sin, sizeof(sin));
    299 	if (! listener) {
    300 		fprintf(stderr, "Couldn't create listener");
    301 		return 1;
    302 	}
    303 
    304 	slen = sizeof(ss);
    305 	if (getsockname(evconnlistener_get_fd(listener), (struct sockaddr *)&ss,
    306 		&slen) < 0) {
    307 		perror("getsockname");
    308 		return 1;
    309 	}
    310 
    311 	if (cfg_connlimit > 0) {
    312 		conn_bucket_cfg = ev_token_bucket_cfg_new(
    313 			cfg_connlimit, cfg_connlimit * 4,
    314 			cfg_connlimit, cfg_connlimit * 4,
    315 			&cfg_tick);
    316 		assert(conn_bucket_cfg);
    317 	}
    318 
    319 	if (cfg_grouplimit > 0) {
    320 		group_bucket_cfg = ev_token_bucket_cfg_new(
    321 			cfg_grouplimit, cfg_grouplimit * 4,
    322 			cfg_grouplimit, cfg_grouplimit * 4,
    323 			&cfg_tick);
    324 		group = ratelim_group = bufferevent_rate_limit_group_new(
    325 			base, group_bucket_cfg);
    326 		expected_total_persec = cfg_grouplimit - (cfg_group_drain / seconds_per_tick);
    327 		expected_avg_persec = cfg_grouplimit / cfg_n_connections;
    328 		if (cfg_connlimit > 0 && expected_avg_persec > cfg_connlimit)
    329 			expected_avg_persec = cfg_connlimit;
    330 		if (cfg_min_share >= 0)
    331 			bufferevent_rate_limit_group_set_min_share(
    332 				ratelim_group, cfg_min_share);
    333 	}
    334 
    335 	if (expected_avg_persec < 0 && cfg_connlimit > 0)
    336 		expected_avg_persec = cfg_connlimit;
    337 
    338 	if (expected_avg_persec > 0)
    339 		expected_avg_persec /= seconds_per_tick;
    340 	if (expected_total_persec > 0)
    341 		expected_total_persec /= seconds_per_tick;
    342 
    343 	bevs = calloc(cfg_n_connections, sizeof(struct bufferevent *));
    344 	states = calloc(cfg_n_connections, sizeof(struct client_state));
    345 
    346 	for (i = 0; i < cfg_n_connections; ++i) {
    347 		bevs[i] = bufferevent_socket_new(base, -1,
    348 		    BEV_OPT_CLOSE_ON_FREE|BEV_OPT_THREADSAFE);
    349 		assert(bevs[i]);
    350 		bufferevent_setcb(bevs[i], discard_readcb, loud_writecb,
    351 		    write_on_connectedcb, &states[i]);
    352 		bufferevent_enable(bevs[i], EV_READ|EV_WRITE);
    353 		bufferevent_socket_connect(bevs[i], (struct sockaddr *)&ss,
    354 		    slen);
    355 	}
    356 
    357 	tv.tv_sec = cfg_duration - 1;
    358 	tv.tv_usec = 995000;
    359 
    360 	event_base_loopexit(base, &tv);
    361 
    362 	tv.tv_sec = 0;
    363 	tv.tv_usec = 100*1000;
    364 	ms100_common = event_base_init_common_timeout(base, &tv);
    365 
    366 	periodic_level_check = event_new(base, -1, EV_PERSIST, check_group_bucket_levels_cb, NULL);
    367 	event_add(periodic_level_check, ms100_common);
    368 
    369 	if (cfg_group_drain && ratelim_group) {
    370 		group_drain_event = event_new(base, -1, EV_PERSIST, group_drain_cb, NULL);
    371 		event_add(group_drain_event, &cfg_tick);
    372 	}
    373 
    374 	event_base_dispatch(base);
    375 
    376 	ratelim_group = NULL; /* So no more responders get added */
    377 	event_free(periodic_level_check);
    378 	if (group_drain_event)
    379 		event_del(group_drain_event);
    380 
    381 	for (i = 0; i < cfg_n_connections; ++i) {
    382 		bufferevent_free(bevs[i]);
    383 	}
    384 	evconnlistener_free(listener);
    385 
    386 	/* Make sure no new echo_conns get added to the group. */
    387 	ratelim_group = NULL;
    388 
    389 	/* This should get _everybody_ freed */
    390 	while (n_echo_conns_open) {
    391 		printf("waiting for %d conns\n", n_echo_conns_open);
    392 		tv.tv_sec = 0;
    393 		tv.tv_usec = 300000;
    394 		event_base_loopexit(base, &tv);
    395 		event_base_dispatch(base);
    396 	}
    397 
    398 	if (group)
    399 		bufferevent_rate_limit_group_free(group);
    400 
    401 	if (total_n_bev_checks) {
    402 		printf("Average read bucket level: %f\n",
    403 		    (double)total_rbucket_level/total_n_bev_checks);
    404 		printf("Average write bucket level: %f\n",
    405 		    (double)total_wbucket_level/total_n_bev_checks);
    406 		printf("Highest read bucket level: %f\n",
    407 		    (double)max_bucket_level);
    408 		printf("Highest write bucket level: %f\n",
    409 		    (double)min_bucket_level);
    410 		printf("Average max-to-read: %f\n",
    411 		    ((double)total_max_to_read)/total_n_bev_checks);
    412 		printf("Average max-to-write: %f\n",
    413 		    ((double)total_max_to_write)/total_n_bev_checks);
    414 	}
    415 	if (total_n_group_bev_checks) {
    416 		printf("Average group read bucket level: %f\n",
    417 		    ((double)total_group_rbucket_level)/total_n_group_bev_checks);
    418 		printf("Average group write bucket level: %f\n",
    419 		    ((double)total_group_wbucket_level)/total_n_group_bev_checks);
    420 	}
    421 
    422 	total_received = 0;
    423 	total_persec = 0.0;
    424 	total_sq_persec = 0.0;
    425 	for (i=0; i < cfg_n_connections; ++i) {
    426 		double persec = states[i].received;
    427 		persec /= cfg_duration;
    428 		total_received += states[i].received;
    429 		total_persec += persec;
    430 		total_sq_persec += persec*persec;
    431 		printf("%d: %f per second\n", i+1, persec);
    432 	}
    433 	printf("   total: %f per second\n",
    434 	    ((double)total_received)/cfg_duration);
    435 	if (expected_total_persec > 0) {
    436 		double diff = expected_total_persec -
    437 		    ((double)total_received/cfg_duration);
    438 		printf("  [Off by %lf]\n", diff);
    439 		if (cfg_grouplimit_tolerance > 0 &&
    440 		    fabs(diff) > cfg_grouplimit_tolerance) {
    441 			fprintf(stderr, "Group bandwidth out of bounds\n");
    442 			ok = 0;
    443 		}
    444 	}
    445 
    446 	printf(" average: %f per second\n",
    447 	    (((double)total_received)/cfg_duration)/cfg_n_connections);
    448 	if (expected_avg_persec > 0) {
    449 		double diff = expected_avg_persec - (((double)total_received)/cfg_duration)/cfg_n_connections;
    450 		printf("  [Off by %lf]\n", diff);
    451 		if (cfg_connlimit_tolerance > 0 &&
    452 		    fabs(diff) > cfg_connlimit_tolerance) {
    453 			fprintf(stderr, "Connection bandwidth out of bounds\n");
    454 			ok = 0;
    455 		}
    456 	}
    457 
    458 	variance = total_sq_persec/cfg_n_connections - total_persec*total_persec/(cfg_n_connections*cfg_n_connections);
    459 
    460 	printf("  stddev: %f per second\n", sqrt(variance));
    461 	if (cfg_stddev_tolerance > 0 &&
    462 	    sqrt(variance) > cfg_stddev_tolerance) {
    463 		fprintf(stderr, "Connection variance out of bounds\n");
    464 		ok = 0;
    465 	}
    466 
    467 	event_base_free(base);
    468 	free(bevs);
    469 	free(states);
    470 
    471 	return ok ? 0 : 1;
    472 }
    473 
    474 static struct option {
    475 	const char *name; int *ptr; int min; int isbool;
    476 } options[] = {
    477 	{ "-v", &cfg_verbose, 0, 1 },
    478 	{ "-h", &cfg_help, 0, 1 },
    479 	{ "-n", &cfg_n_connections, 1, 0 },
    480 	{ "-d", &cfg_duration, 1, 0 },
    481 	{ "-c", &cfg_connlimit, 0, 0 },
    482 	{ "-g", &cfg_grouplimit, 0, 0 },
    483 	{ "-G", &cfg_group_drain, -100000, 0 },
    484 	{ "-t", &cfg_tick_msec, 10, 0 },
    485 	{ "--min-share", &cfg_min_share, 0, 0 },
    486 	{ "--check-connlimit", &cfg_connlimit_tolerance, 0, 0 },
    487 	{ "--check-grouplimit", &cfg_grouplimit_tolerance, 0, 0 },
    488 	{ "--check-stddev", &cfg_stddev_tolerance, 0, 0 },
    489 #ifdef _WIN32
    490 	{ "--iocp", &cfg_enable_iocp, 0, 1 },
    491 #endif
    492 	{ NULL, NULL, -1, 0 },
    493 };
    494 
    495 static int
    496 handle_option(int argc, char **argv, int *i, const struct option *opt)
    497 {
    498 	long val;
    499 	char *endptr = NULL;
    500 	if (opt->isbool) {
    501 		*opt->ptr = 1;
    502 		return 0;
    503 	}
    504 	if (*i + 1 == argc) {
    505 		fprintf(stderr, "Too few arguments to '%s'\n",argv[*i]);
    506 		return -1;
    507 	}
    508 	val = strtol(argv[*i+1], &endptr, 10);
    509 	if (*argv[*i+1] == '\0' || !endptr || *endptr != '\0') {
    510 		fprintf(stderr, "Couldn't parse numeric value '%s'\n",
    511 		    argv[*i+1]);
    512 		return -1;
    513 	}
    514 	if (val < opt->min || val > 0x7fffffff) {
    515 		fprintf(stderr, "Value '%s' is out-of-range'\n",
    516 		    argv[*i+1]);
    517 		return -1;
    518 	}
    519 	*opt->ptr = (int)val;
    520 	++*i;
    521 	return 0;
    522 }
    523 
    524 static void
    525 usage(void)
    526 {
    527 	fprintf(stderr,
    528 "test-ratelim [-v] [-n INT] [-d INT] [-c INT] [-g INT] [-t INT]\n\n"
    529 "Pushes bytes through a number of possibly rate-limited connections, and\n"
    530 "displays average throughput.\n\n"
    531 "  -n INT: Number of connections to open (default: 30)\n"
    532 "  -d INT: Duration of the test in seconds (default: 5 sec)\n");
    533 	fprintf(stderr,
    534 "  -c INT: Connection-rate limit applied to each connection in bytes per second\n"
    535 "	   (default: None.)\n"
    536 "  -g INT: Group-rate limit applied to sum of all usage in bytes per second\n"
    537 "	   (default: None.)\n"
    538 "  -G INT: drain INT bytes from the group limit every tick. (default: 0)\n"
    539 "  -t INT: Granularity of timing, in milliseconds (default: 1000 msec)\n");
    540 }
    541 
    542 int
    543 main(int argc, char **argv)
    544 {
    545 	int i,j;
    546 	double ratio;
    547 
    548 #ifdef _WIN32
    549 	WORD wVersionRequested = MAKEWORD(2,2);
    550 	WSADATA wsaData;
    551 
    552 	(void) WSAStartup(wVersionRequested, &wsaData);
    553 #endif
    554 
    555 	evutil_weakrand_seed_(&weakrand_state, 0);
    556 
    557 #ifndef _WIN32
    558 	if (signal(SIGPIPE, SIG_IGN) == SIG_ERR)
    559 		return 1;
    560 #endif
    561 	for (i = 1; i < argc; ++i) {
    562 		for (j = 0; options[j].name; ++j) {
    563 			if (!strcmp(argv[i],options[j].name)) {
    564 				if (handle_option(argc,argv,&i,&options[j])<0)
    565 					return 1;
    566 				goto again;
    567 			}
    568 		}
    569 		fprintf(stderr, "Unknown option '%s'\n", argv[i]);
    570 		usage();
    571 		return 1;
    572 	again:
    573 		;
    574 	}
    575 	if (cfg_help) {
    576 		usage();
    577 		return 0;
    578 	}
    579 
    580 	cfg_tick.tv_sec = cfg_tick_msec / 1000;
    581 	cfg_tick.tv_usec = (cfg_tick_msec % 1000)*1000;
    582 
    583 	seconds_per_tick = ratio = cfg_tick_msec / 1000.0;
    584 
    585 	cfg_connlimit *= ratio;
    586 	cfg_grouplimit *= ratio;
    587 
    588 	{
    589 		struct timeval tv;
    590 		evutil_gettimeofday(&tv, NULL);
    591 #ifdef _WIN32
    592 		srand(tv.tv_usec);
    593 #else
    594 		srandom(tv.tv_usec);
    595 #endif
    596 	}
    597 
    598 #ifndef EVENT__DISABLE_THREAD_SUPPORT
    599 	evthread_enable_lock_debugging();
    600 #endif
    601 
    602 	return test_ratelimiting();
    603 }
    604