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      1 /*
      2  * Copyright (c) 2009-2012 Niels Provos and Nick Mathewson
      3  *
      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  * 3. The name of the author may not be used to endorse or promote products
     15  *    derived from this software without specific prior written permission.
     16  *
     17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     18  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     19  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     20  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     21  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     22  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     27  */
     28 
     29 #include "event2/event-config.h"
     30 
     31 #ifdef _EVENT_HAVE_SYS_TIME_H
     32 #include <sys/time.h>
     33 #endif
     34 
     35 #include <errno.h>
     36 #include <stdio.h>
     37 #include <stdlib.h>
     38 #include <string.h>
     39 #ifdef _EVENT_HAVE_STDARG_H
     40 #include <stdarg.h>
     41 #endif
     42 #ifdef _EVENT_HAVE_UNISTD_H
     43 #include <unistd.h>
     44 #endif
     45 
     46 #ifdef WIN32
     47 #include <winsock2.h>
     48 #include <ws2tcpip.h>
     49 #endif
     50 
     51 #include <sys/queue.h>
     52 
     53 #include "event2/util.h"
     54 #include "event2/bufferevent.h"
     55 #include "event2/buffer.h"
     56 #include "event2/bufferevent_struct.h"
     57 #include "event2/event.h"
     58 #include "event2/util.h"
     59 #include "event-internal.h"
     60 #include "log-internal.h"
     61 #include "mm-internal.h"
     62 #include "bufferevent-internal.h"
     63 #include "util-internal.h"
     64 #include "iocp-internal.h"
     65 
     66 #ifndef SO_UPDATE_CONNECT_CONTEXT
     67 /* Mingw is sometimes missing this */
     68 #define SO_UPDATE_CONNECT_CONTEXT 0x7010
     69 #endif
     70 
     71 /* prototypes */
     72 static int be_async_enable(struct bufferevent *, short);
     73 static int be_async_disable(struct bufferevent *, short);
     74 static void be_async_destruct(struct bufferevent *);
     75 static int be_async_flush(struct bufferevent *, short, enum bufferevent_flush_mode);
     76 static int be_async_ctrl(struct bufferevent *, enum bufferevent_ctrl_op, union bufferevent_ctrl_data *);
     77 
     78 struct bufferevent_async {
     79 	struct bufferevent_private bev;
     80 	struct event_overlapped connect_overlapped;
     81 	struct event_overlapped read_overlapped;
     82 	struct event_overlapped write_overlapped;
     83 	size_t read_in_progress;
     84 	size_t write_in_progress;
     85 	unsigned ok : 1;
     86 	unsigned read_added : 1;
     87 	unsigned write_added : 1;
     88 };
     89 
     90 const struct bufferevent_ops bufferevent_ops_async = {
     91 	"socket_async",
     92 	evutil_offsetof(struct bufferevent_async, bev.bev),
     93 	be_async_enable,
     94 	be_async_disable,
     95 	be_async_destruct,
     96 	_bufferevent_generic_adj_timeouts,
     97 	be_async_flush,
     98 	be_async_ctrl,
     99 };
    100 
    101 static inline struct bufferevent_async *
    102 upcast(struct bufferevent *bev)
    103 {
    104 	struct bufferevent_async *bev_a;
    105 	if (bev->be_ops != &bufferevent_ops_async)
    106 		return NULL;
    107 	bev_a = EVUTIL_UPCAST(bev, struct bufferevent_async, bev.bev);
    108 	return bev_a;
    109 }
    110 
    111 static inline struct bufferevent_async *
    112 upcast_connect(struct event_overlapped *eo)
    113 {
    114 	struct bufferevent_async *bev_a;
    115 	bev_a = EVUTIL_UPCAST(eo, struct bufferevent_async, connect_overlapped);
    116 	EVUTIL_ASSERT(BEV_IS_ASYNC(&bev_a->bev.bev));
    117 	return bev_a;
    118 }
    119 
    120 static inline struct bufferevent_async *
    121 upcast_read(struct event_overlapped *eo)
    122 {
    123 	struct bufferevent_async *bev_a;
    124 	bev_a = EVUTIL_UPCAST(eo, struct bufferevent_async, read_overlapped);
    125 	EVUTIL_ASSERT(BEV_IS_ASYNC(&bev_a->bev.bev));
    126 	return bev_a;
    127 }
    128 
    129 static inline struct bufferevent_async *
    130 upcast_write(struct event_overlapped *eo)
    131 {
    132 	struct bufferevent_async *bev_a;
    133 	bev_a = EVUTIL_UPCAST(eo, struct bufferevent_async, write_overlapped);
    134 	EVUTIL_ASSERT(BEV_IS_ASYNC(&bev_a->bev.bev));
    135 	return bev_a;
    136 }
    137 
    138 static void
    139 bev_async_del_write(struct bufferevent_async *beva)
    140 {
    141 	struct bufferevent *bev = &beva->bev.bev;
    142 
    143 	if (beva->write_added) {
    144 		beva->write_added = 0;
    145 		event_base_del_virtual(bev->ev_base);
    146 	}
    147 }
    148 
    149 static void
    150 bev_async_del_read(struct bufferevent_async *beva)
    151 {
    152 	struct bufferevent *bev = &beva->bev.bev;
    153 
    154 	if (beva->read_added) {
    155 		beva->read_added = 0;
    156 		event_base_del_virtual(bev->ev_base);
    157 	}
    158 }
    159 
    160 static void
    161 bev_async_add_write(struct bufferevent_async *beva)
    162 {
    163 	struct bufferevent *bev = &beva->bev.bev;
    164 
    165 	if (!beva->write_added) {
    166 		beva->write_added = 1;
    167 		event_base_add_virtual(bev->ev_base);
    168 	}
    169 }
    170 
    171 static void
    172 bev_async_add_read(struct bufferevent_async *beva)
    173 {
    174 	struct bufferevent *bev = &beva->bev.bev;
    175 
    176 	if (!beva->read_added) {
    177 		beva->read_added = 1;
    178 		event_base_add_virtual(bev->ev_base);
    179 	}
    180 }
    181 
    182 static void
    183 bev_async_consider_writing(struct bufferevent_async *beva)
    184 {
    185 	size_t at_most;
    186 	int limit;
    187 	struct bufferevent *bev = &beva->bev.bev;
    188 
    189 	/* Don't write if there's a write in progress, or we do not
    190 	 * want to write, or when there's nothing left to write. */
    191 	if (beva->write_in_progress || beva->bev.connecting)
    192 		return;
    193 	if (!beva->ok || !(bev->enabled&EV_WRITE) ||
    194 	    !evbuffer_get_length(bev->output)) {
    195 		bev_async_del_write(beva);
    196 		return;
    197 	}
    198 
    199 	at_most = evbuffer_get_length(bev->output);
    200 
    201 	/* This is safe so long as bufferevent_get_write_max never returns
    202 	 * more than INT_MAX.  That's true for now. XXXX */
    203 	limit = (int)_bufferevent_get_write_max(&beva->bev);
    204 	if (at_most >= (size_t)limit && limit >= 0)
    205 		at_most = limit;
    206 
    207 	if (beva->bev.write_suspended) {
    208 		bev_async_del_write(beva);
    209 		return;
    210 	}
    211 
    212 	/*  XXXX doesn't respect low-water mark very well. */
    213 	bufferevent_incref(bev);
    214 	if (evbuffer_launch_write(bev->output, at_most,
    215 	    &beva->write_overlapped)) {
    216 		bufferevent_decref(bev);
    217 		beva->ok = 0;
    218 		_bufferevent_run_eventcb(bev, BEV_EVENT_ERROR);
    219 	} else {
    220 		beva->write_in_progress = at_most;
    221 		_bufferevent_decrement_write_buckets(&beva->bev, at_most);
    222 		bev_async_add_write(beva);
    223 	}
    224 }
    225 
    226 static void
    227 bev_async_consider_reading(struct bufferevent_async *beva)
    228 {
    229 	size_t cur_size;
    230 	size_t read_high;
    231 	size_t at_most;
    232 	int limit;
    233 	struct bufferevent *bev = &beva->bev.bev;
    234 
    235 	/* Don't read if there is a read in progress, or we do not
    236 	 * want to read. */
    237 	if (beva->read_in_progress || beva->bev.connecting)
    238 		return;
    239 	if (!beva->ok || !(bev->enabled&EV_READ)) {
    240 		bev_async_del_read(beva);
    241 		return;
    242 	}
    243 
    244 	/* Don't read if we're full */
    245 	cur_size = evbuffer_get_length(bev->input);
    246 	read_high = bev->wm_read.high;
    247 	if (read_high) {
    248 		if (cur_size >= read_high) {
    249 			bev_async_del_read(beva);
    250 			return;
    251 		}
    252 		at_most = read_high - cur_size;
    253 	} else {
    254 		at_most = 16384; /* FIXME totally magic. */
    255 	}
    256 
    257 	/* XXXX This over-commits. */
    258 	/* XXXX see also not above on cast on _bufferevent_get_write_max() */
    259 	limit = (int)_bufferevent_get_read_max(&beva->bev);
    260 	if (at_most >= (size_t)limit && limit >= 0)
    261 		at_most = limit;
    262 
    263 	if (beva->bev.read_suspended) {
    264 		bev_async_del_read(beva);
    265 		return;
    266 	}
    267 
    268 	bufferevent_incref(bev);
    269 	if (evbuffer_launch_read(bev->input, at_most, &beva->read_overlapped)) {
    270 		beva->ok = 0;
    271 		_bufferevent_run_eventcb(bev, BEV_EVENT_ERROR);
    272 		bufferevent_decref(bev);
    273 	} else {
    274 		beva->read_in_progress = at_most;
    275 		_bufferevent_decrement_read_buckets(&beva->bev, at_most);
    276 		bev_async_add_read(beva);
    277 	}
    278 
    279 	return;
    280 }
    281 
    282 static void
    283 be_async_outbuf_callback(struct evbuffer *buf,
    284     const struct evbuffer_cb_info *cbinfo,
    285     void *arg)
    286 {
    287 	struct bufferevent *bev = arg;
    288 	struct bufferevent_async *bev_async = upcast(bev);
    289 
    290 	/* If we added data to the outbuf and were not writing before,
    291 	 * we may want to write now. */
    292 
    293 	_bufferevent_incref_and_lock(bev);
    294 
    295 	if (cbinfo->n_added)
    296 		bev_async_consider_writing(bev_async);
    297 
    298 	_bufferevent_decref_and_unlock(bev);
    299 }
    300 
    301 static void
    302 be_async_inbuf_callback(struct evbuffer *buf,
    303     const struct evbuffer_cb_info *cbinfo,
    304     void *arg)
    305 {
    306 	struct bufferevent *bev = arg;
    307 	struct bufferevent_async *bev_async = upcast(bev);
    308 
    309 	/* If we drained data from the inbuf and were not reading before,
    310 	 * we may want to read now */
    311 
    312 	_bufferevent_incref_and_lock(bev);
    313 
    314 	if (cbinfo->n_deleted)
    315 		bev_async_consider_reading(bev_async);
    316 
    317 	_bufferevent_decref_and_unlock(bev);
    318 }
    319 
    320 static int
    321 be_async_enable(struct bufferevent *buf, short what)
    322 {
    323 	struct bufferevent_async *bev_async = upcast(buf);
    324 
    325 	if (!bev_async->ok)
    326 		return -1;
    327 
    328 	if (bev_async->bev.connecting) {
    329 		/* Don't launch anything during connection attempts. */
    330 		return 0;
    331 	}
    332 
    333 	if (what & EV_READ)
    334 		BEV_RESET_GENERIC_READ_TIMEOUT(buf);
    335 	if (what & EV_WRITE)
    336 		BEV_RESET_GENERIC_WRITE_TIMEOUT(buf);
    337 
    338 	/* If we newly enable reading or writing, and we aren't reading or
    339 	   writing already, consider launching a new read or write. */
    340 
    341 	if (what & EV_READ)
    342 		bev_async_consider_reading(bev_async);
    343 	if (what & EV_WRITE)
    344 		bev_async_consider_writing(bev_async);
    345 	return 0;
    346 }
    347 
    348 static int
    349 be_async_disable(struct bufferevent *bev, short what)
    350 {
    351 	struct bufferevent_async *bev_async = upcast(bev);
    352 	/* XXXX If we disable reading or writing, we may want to consider
    353 	 * canceling any in-progress read or write operation, though it might
    354 	 * not work. */
    355 
    356 	if (what & EV_READ) {
    357 		BEV_DEL_GENERIC_READ_TIMEOUT(bev);
    358 		bev_async_del_read(bev_async);
    359 	}
    360 	if (what & EV_WRITE) {
    361 		BEV_DEL_GENERIC_WRITE_TIMEOUT(bev);
    362 		bev_async_del_write(bev_async);
    363 	}
    364 
    365 	return 0;
    366 }
    367 
    368 static void
    369 be_async_destruct(struct bufferevent *bev)
    370 {
    371 	struct bufferevent_async *bev_async = upcast(bev);
    372 	struct bufferevent_private *bev_p = BEV_UPCAST(bev);
    373 	evutil_socket_t fd;
    374 
    375 	EVUTIL_ASSERT(!upcast(bev)->write_in_progress &&
    376 			!upcast(bev)->read_in_progress);
    377 
    378 	bev_async_del_read(bev_async);
    379 	bev_async_del_write(bev_async);
    380 
    381 	fd = _evbuffer_overlapped_get_fd(bev->input);
    382 	if (bev_p->options & BEV_OPT_CLOSE_ON_FREE) {
    383 		/* XXXX possible double-close */
    384 		evutil_closesocket(fd);
    385 	}
    386 	/* delete this in case non-blocking connect was used */
    387 	if (event_initialized(&bev->ev_write)) {
    388 		event_del(&bev->ev_write);
    389 		_bufferevent_del_generic_timeout_cbs(bev);
    390 	}
    391 }
    392 
    393 /* GetQueuedCompletionStatus doesn't reliably yield WSA error codes, so
    394  * we use WSAGetOverlappedResult to translate. */
    395 static void
    396 bev_async_set_wsa_error(struct bufferevent *bev, struct event_overlapped *eo)
    397 {
    398 	DWORD bytes, flags;
    399 	evutil_socket_t fd;
    400 
    401 	fd = _evbuffer_overlapped_get_fd(bev->input);
    402 	WSAGetOverlappedResult(fd, &eo->overlapped, &bytes, FALSE, &flags);
    403 }
    404 
    405 static int
    406 be_async_flush(struct bufferevent *bev, short what,
    407     enum bufferevent_flush_mode mode)
    408 {
    409 	return 0;
    410 }
    411 
    412 static void
    413 connect_complete(struct event_overlapped *eo, ev_uintptr_t key,
    414     ev_ssize_t nbytes, int ok)
    415 {
    416 	struct bufferevent_async *bev_a = upcast_connect(eo);
    417 	struct bufferevent *bev = &bev_a->bev.bev;
    418 	evutil_socket_t sock;
    419 
    420 	BEV_LOCK(bev);
    421 
    422 	EVUTIL_ASSERT(bev_a->bev.connecting);
    423 	bev_a->bev.connecting = 0;
    424 	sock = _evbuffer_overlapped_get_fd(bev_a->bev.bev.input);
    425 	/* XXXX Handle error? */
    426 	setsockopt(sock, SOL_SOCKET, SO_UPDATE_CONNECT_CONTEXT, NULL, 0);
    427 
    428 	if (ok)
    429 		bufferevent_async_set_connected(bev);
    430 	else
    431 		bev_async_set_wsa_error(bev, eo);
    432 
    433 	_bufferevent_run_eventcb(bev,
    434 			ok? BEV_EVENT_CONNECTED : BEV_EVENT_ERROR);
    435 
    436 	event_base_del_virtual(bev->ev_base);
    437 
    438 	_bufferevent_decref_and_unlock(bev);
    439 }
    440 
    441 static void
    442 read_complete(struct event_overlapped *eo, ev_uintptr_t key,
    443     ev_ssize_t nbytes, int ok)
    444 {
    445 	struct bufferevent_async *bev_a = upcast_read(eo);
    446 	struct bufferevent *bev = &bev_a->bev.bev;
    447 	short what = BEV_EVENT_READING;
    448 	ev_ssize_t amount_unread;
    449 	BEV_LOCK(bev);
    450 	EVUTIL_ASSERT(bev_a->read_in_progress);
    451 
    452 	amount_unread = bev_a->read_in_progress - nbytes;
    453 	evbuffer_commit_read(bev->input, nbytes);
    454 	bev_a->read_in_progress = 0;
    455 	if (amount_unread)
    456 		_bufferevent_decrement_read_buckets(&bev_a->bev, -amount_unread);
    457 
    458 	if (!ok)
    459 		bev_async_set_wsa_error(bev, eo);
    460 
    461 	if (bev_a->ok) {
    462 		if (ok && nbytes) {
    463 			BEV_RESET_GENERIC_READ_TIMEOUT(bev);
    464 			if (evbuffer_get_length(bev->input) >= bev->wm_read.low)
    465 				_bufferevent_run_readcb(bev);
    466 			bev_async_consider_reading(bev_a);
    467 		} else if (!ok) {
    468 			what |= BEV_EVENT_ERROR;
    469 			bev_a->ok = 0;
    470 			_bufferevent_run_eventcb(bev, what);
    471 		} else if (!nbytes) {
    472 			what |= BEV_EVENT_EOF;
    473 			bev_a->ok = 0;
    474 			_bufferevent_run_eventcb(bev, what);
    475 		}
    476 	}
    477 
    478 	_bufferevent_decref_and_unlock(bev);
    479 }
    480 
    481 static void
    482 write_complete(struct event_overlapped *eo, ev_uintptr_t key,
    483     ev_ssize_t nbytes, int ok)
    484 {
    485 	struct bufferevent_async *bev_a = upcast_write(eo);
    486 	struct bufferevent *bev = &bev_a->bev.bev;
    487 	short what = BEV_EVENT_WRITING;
    488 	ev_ssize_t amount_unwritten;
    489 
    490 	BEV_LOCK(bev);
    491 	EVUTIL_ASSERT(bev_a->write_in_progress);
    492 
    493 	amount_unwritten = bev_a->write_in_progress - nbytes;
    494 	evbuffer_commit_write(bev->output, nbytes);
    495 	bev_a->write_in_progress = 0;
    496 
    497 	if (amount_unwritten)
    498 		_bufferevent_decrement_write_buckets(&bev_a->bev,
    499 		                                     -amount_unwritten);
    500 
    501 
    502 	if (!ok)
    503 		bev_async_set_wsa_error(bev, eo);
    504 
    505 	if (bev_a->ok) {
    506 		if (ok && nbytes) {
    507 			BEV_RESET_GENERIC_WRITE_TIMEOUT(bev);
    508 			if (evbuffer_get_length(bev->output) <=
    509 			    bev->wm_write.low)
    510 				_bufferevent_run_writecb(bev);
    511 			bev_async_consider_writing(bev_a);
    512 		} else if (!ok) {
    513 			what |= BEV_EVENT_ERROR;
    514 			bev_a->ok = 0;
    515 			_bufferevent_run_eventcb(bev, what);
    516 		} else if (!nbytes) {
    517 			what |= BEV_EVENT_EOF;
    518 			bev_a->ok = 0;
    519 			_bufferevent_run_eventcb(bev, what);
    520 		}
    521 	}
    522 
    523 	_bufferevent_decref_and_unlock(bev);
    524 }
    525 
    526 struct bufferevent *
    527 bufferevent_async_new(struct event_base *base,
    528     evutil_socket_t fd, int options)
    529 {
    530 	struct bufferevent_async *bev_a;
    531 	struct bufferevent *bev;
    532 	struct event_iocp_port *iocp;
    533 
    534 	options |= BEV_OPT_THREADSAFE;
    535 
    536 	if (!(iocp = event_base_get_iocp(base)))
    537 		return NULL;
    538 
    539 	if (fd >= 0 && event_iocp_port_associate(iocp, fd, 1)<0) {
    540 		int err = GetLastError();
    541 		/* We may have alrady associated this fd with a port.
    542 		 * Let's hope it's this port, and that the error code
    543 		 * for doing this neer changes. */
    544 		if (err != ERROR_INVALID_PARAMETER)
    545 			return NULL;
    546 	}
    547 
    548 	if (!(bev_a = mm_calloc(1, sizeof(struct bufferevent_async))))
    549 		return NULL;
    550 
    551 	bev = &bev_a->bev.bev;
    552 	if (!(bev->input = evbuffer_overlapped_new(fd))) {
    553 		mm_free(bev_a);
    554 		return NULL;
    555 	}
    556 	if (!(bev->output = evbuffer_overlapped_new(fd))) {
    557 		evbuffer_free(bev->input);
    558 		mm_free(bev_a);
    559 		return NULL;
    560 	}
    561 
    562 	if (bufferevent_init_common(&bev_a->bev, base, &bufferevent_ops_async,
    563 		options)<0)
    564 		goto err;
    565 
    566 	evbuffer_add_cb(bev->input, be_async_inbuf_callback, bev);
    567 	evbuffer_add_cb(bev->output, be_async_outbuf_callback, bev);
    568 
    569 	event_overlapped_init(&bev_a->connect_overlapped, connect_complete);
    570 	event_overlapped_init(&bev_a->read_overlapped, read_complete);
    571 	event_overlapped_init(&bev_a->write_overlapped, write_complete);
    572 
    573 	bev_a->ok = fd >= 0;
    574 	if (bev_a->ok)
    575 		_bufferevent_init_generic_timeout_cbs(bev);
    576 
    577 	return bev;
    578 err:
    579 	bufferevent_free(&bev_a->bev.bev);
    580 	return NULL;
    581 }
    582 
    583 void
    584 bufferevent_async_set_connected(struct bufferevent *bev)
    585 {
    586 	struct bufferevent_async *bev_async = upcast(bev);
    587 	bev_async->ok = 1;
    588 	_bufferevent_init_generic_timeout_cbs(bev);
    589 	/* Now's a good time to consider reading/writing */
    590 	be_async_enable(bev, bev->enabled);
    591 }
    592 
    593 int
    594 bufferevent_async_can_connect(struct bufferevent *bev)
    595 {
    596 	const struct win32_extension_fns *ext =
    597 	    event_get_win32_extension_fns();
    598 
    599 	if (BEV_IS_ASYNC(bev) &&
    600 	    event_base_get_iocp(bev->ev_base) &&
    601 	    ext && ext->ConnectEx)
    602 		return 1;
    603 
    604 	return 0;
    605 }
    606 
    607 int
    608 bufferevent_async_connect(struct bufferevent *bev, evutil_socket_t fd,
    609 	const struct sockaddr *sa, int socklen)
    610 {
    611 	BOOL rc;
    612 	struct bufferevent_async *bev_async = upcast(bev);
    613 	struct sockaddr_storage ss;
    614 	const struct win32_extension_fns *ext =
    615 	    event_get_win32_extension_fns();
    616 
    617 	EVUTIL_ASSERT(ext && ext->ConnectEx && fd >= 0 && sa != NULL);
    618 
    619 	/* ConnectEx() requires that the socket be bound to an address
    620 	 * with bind() before using, otherwise it will fail. We attempt
    621 	 * to issue a bind() here, taking into account that the error
    622 	 * code is set to WSAEINVAL when the socket is already bound. */
    623 	memset(&ss, 0, sizeof(ss));
    624 	if (sa->sa_family == AF_INET) {
    625 		struct sockaddr_in *sin = (struct sockaddr_in *)&ss;
    626 		sin->sin_family = AF_INET;
    627 		sin->sin_addr.s_addr = INADDR_ANY;
    628 	} else if (sa->sa_family == AF_INET6) {
    629 		struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)&ss;
    630 		sin6->sin6_family = AF_INET6;
    631 		sin6->sin6_addr = in6addr_any;
    632 	} else {
    633 		/* Well, the user will have to bind() */
    634 		return -1;
    635 	}
    636 	if (bind(fd, (struct sockaddr *)&ss, sizeof(ss)) < 0 &&
    637 	    WSAGetLastError() != WSAEINVAL)
    638 		return -1;
    639 
    640 	event_base_add_virtual(bev->ev_base);
    641 	bufferevent_incref(bev);
    642 	rc = ext->ConnectEx(fd, sa, socklen, NULL, 0, NULL,
    643 			    &bev_async->connect_overlapped.overlapped);
    644 	if (rc || WSAGetLastError() == ERROR_IO_PENDING)
    645 		return 0;
    646 
    647 	event_base_del_virtual(bev->ev_base);
    648 	bufferevent_decref(bev);
    649 
    650 	return -1;
    651 }
    652 
    653 static int
    654 be_async_ctrl(struct bufferevent *bev, enum bufferevent_ctrl_op op,
    655     union bufferevent_ctrl_data *data)
    656 {
    657 	switch (op) {
    658 	case BEV_CTRL_GET_FD:
    659 		data->fd = _evbuffer_overlapped_get_fd(bev->input);
    660 		return 0;
    661 	case BEV_CTRL_SET_FD: {
    662 		struct event_iocp_port *iocp;
    663 
    664 		if (data->fd == _evbuffer_overlapped_get_fd(bev->input))
    665 			return 0;
    666 		if (!(iocp = event_base_get_iocp(bev->ev_base)))
    667 			return -1;
    668 		if (event_iocp_port_associate(iocp, data->fd, 1) < 0)
    669 			return -1;
    670 		_evbuffer_overlapped_set_fd(bev->input, data->fd);
    671 		_evbuffer_overlapped_set_fd(bev->output, data->fd);
    672 		return 0;
    673 	}
    674 	case BEV_CTRL_CANCEL_ALL: {
    675 		struct bufferevent_async *bev_a = upcast(bev);
    676 		evutil_socket_t fd = _evbuffer_overlapped_get_fd(bev->input);
    677 		if (fd != (evutil_socket_t)INVALID_SOCKET &&
    678 		    (bev_a->bev.options & BEV_OPT_CLOSE_ON_FREE)) {
    679 			closesocket(fd);
    680 		}
    681 		bev_a->ok = 0;
    682 		return 0;
    683 	}
    684 	case BEV_CTRL_GET_UNDERLYING:
    685 	default:
    686 		return -1;
    687 	}
    688 }
    689 
    690 
    691