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kc3-lang/libevent/listener.c

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  • Author : kenping
    Date : 2022-04-21 15:59:28
    Hash : d96457e1
    Message : listener: Preserve last error in evconnlistener_new_bind() before close In function evconnlistener_new_bind() after go to "err:", The evutil_closesocket() would clear the error code( I found this under Windows ). User can not use EVUTIL_SOCKET_ERROR() to get the evconnlistener_new_bind()'s failing error. I add a err_code variable to store and restore the last error code. v2: rebased by azat to make the patch simpler

  • listener.c
  • /*
     * Copyright (c) 2009-2012 Niels Provos, Nick Mathewson
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. The name of the author may not be used to endorse or promote products
     *    derived from this software without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     */
    
    #include "event2/event-config.h"
    #include "evconfig-private.h"
    
    #include <sys/types.h>
    
    #ifdef _WIN32
    #ifndef _WIN32_WINNT
    /* Minimum required for InitializeCriticalSectionAndSpinCount */
    #define _WIN32_WINNT 0x0403
    #endif
    #include <winsock2.h>
    #include <winerror.h>
    #include <ws2tcpip.h>
    #include <mswsock.h>
    #endif
    #ifdef EVENT__HAVE_AFUNIX_H
    #include <afunix.h>
    #endif
    #include <errno.h>
    #ifdef EVENT__HAVE_SYS_SOCKET_H
    #include <sys/socket.h>
    #endif
    #ifdef EVENT__HAVE_FCNTL_H
    #include <fcntl.h>
    #endif
    #ifdef EVENT__HAVE_UNISTD_H
    #include <unistd.h>
    #endif
    
    #include "event2/listener.h"
    #include "event2/util.h"
    #include "event2/event.h"
    #include "event2/event_struct.h"
    #include "mm-internal.h"
    #include "util-internal.h"
    #include "log-internal.h"
    #include "evthread-internal.h"
    #ifdef _WIN32
    #include "iocp-internal.h"
    #include "defer-internal.h"
    #include "event-internal.h"
    #endif
    
    struct evconnlistener_ops {
    	int (*enable)(struct evconnlistener *);
    	int (*disable)(struct evconnlistener *);
    	void (*destroy)(struct evconnlistener *);
    	void (*shutdown)(struct evconnlistener *);
    	evutil_socket_t (*getfd)(struct evconnlistener *);
    	struct event_base *(*getbase)(struct evconnlistener *);
    };
    
    struct evconnlistener {
    	const struct evconnlistener_ops *ops;
    	void *lock;
    	evconnlistener_cb cb;
    	evconnlistener_errorcb errorcb;
    	void *user_data;
    	unsigned flags;
    	short refcnt;
    	int accept4_flags;
    	unsigned enabled : 1;
    };
    
    struct evconnlistener_event {
    	struct evconnlistener base;
    	struct event listener;
    };
    
    #ifdef _WIN32
    struct evconnlistener_iocp {
    	struct evconnlistener base;
    	evutil_socket_t fd;
    	struct event_base *event_base;
    	struct event_iocp_port *port;
    	short n_accepting;
    	unsigned shutting_down : 1;
    	unsigned event_added : 1;
    	struct accepting_socket **accepting;
    };
    #endif
    
    #define LOCK(listener) EVLOCK_LOCK((listener)->lock, 0)
    #define UNLOCK(listener) EVLOCK_UNLOCK((listener)->lock, 0)
    
    struct evconnlistener *
    evconnlistener_new_async(struct event_base *base,
        evconnlistener_cb cb, void *ptr, unsigned flags, int backlog,
        evutil_socket_t fd); /* XXXX export this? */
    
    static int event_listener_enable(struct evconnlistener *);
    static int event_listener_disable(struct evconnlistener *);
    static void event_listener_destroy(struct evconnlistener *);
    static evutil_socket_t event_listener_getfd(struct evconnlistener *);
    static struct event_base *event_listener_getbase(struct evconnlistener *);
    
    #if 0
    static void
    listener_incref_and_lock(struct evconnlistener *listener)
    {
    	LOCK(listener);
    	++listener->refcnt;
    }
    #endif
    
    static int
    listener_decref_and_unlock(struct evconnlistener *listener)
    {
    	int refcnt = --listener->refcnt;
    	if (refcnt == 0) {
    		listener->ops->destroy(listener);
    		UNLOCK(listener);
    		EVTHREAD_FREE_LOCK(listener->lock, EVTHREAD_LOCKTYPE_RECURSIVE);
    		mm_free(listener);
    		return 1;
    	} else {
    		UNLOCK(listener);
    		return 0;
    	}
    }
    
    static const struct evconnlistener_ops evconnlistener_event_ops = {
    	event_listener_enable,
    	event_listener_disable,
    	event_listener_destroy,
    	NULL, /* shutdown */
    	event_listener_getfd,
    	event_listener_getbase
    };
    
    static void listener_read_cb(evutil_socket_t, short, void *);
    
    struct evconnlistener *
    evconnlistener_new(struct event_base *base,
        evconnlistener_cb cb, void *ptr, unsigned flags, int backlog,
        evutil_socket_t fd)
    {
    	struct evconnlistener_event *lev;
    
    #ifdef _WIN32
    	if (base && event_base_get_iocp_(base)) {
    		const struct win32_extension_fns *ext =
    			event_get_win32_extension_fns_();
    		if (ext->AcceptEx && ext->GetAcceptExSockaddrs)
    			return evconnlistener_new_async(base, cb, ptr, flags,
    				backlog, fd);
    	}
    #endif
    
    	if (backlog > 0) {
    		if (listen(fd, backlog) < 0)
    			return NULL;
    	} else if (backlog < 0) {
    		if (listen(fd, 128) < 0)
    			return NULL;
    	}
    
    	lev = mm_calloc(1, sizeof(struct evconnlistener_event));
    	if (!lev)
    		return NULL;
    
    	lev->base.ops = &evconnlistener_event_ops;
    	lev->base.cb = cb;
    	lev->base.user_data = ptr;
    	lev->base.flags = flags;
    	lev->base.refcnt = 1;
    
    	lev->base.accept4_flags = 0;
    	if (!(flags & LEV_OPT_LEAVE_SOCKETS_BLOCKING))
    		lev->base.accept4_flags |= EVUTIL_SOCK_NONBLOCK;
    	if (flags & LEV_OPT_CLOSE_ON_EXEC)
    		lev->base.accept4_flags |= EVUTIL_SOCK_CLOEXEC;
    
    	if (flags & LEV_OPT_THREADSAFE) {
    		EVTHREAD_ALLOC_LOCK(lev->base.lock, EVTHREAD_LOCKTYPE_RECURSIVE);
    	}
    
    	event_assign(&lev->listener, base, fd, EV_READ|EV_PERSIST,
    	    listener_read_cb, lev);
    
    	if (!(flags & LEV_OPT_DISABLED))
    	    evconnlistener_enable(&lev->base);
    
    	return &lev->base;
    }
    
    struct evconnlistener *
    evconnlistener_new_bind(struct event_base *base, evconnlistener_cb cb,
        void *ptr, unsigned flags, int backlog, const struct sockaddr *sa,
        int socklen)
    {
    	struct evconnlistener *listener;
    	evutil_socket_t fd;
    	int on = 1;
    	int family = sa ? sa->sa_family : AF_UNSPEC;
    	int socktype = SOCK_STREAM | EVUTIL_SOCK_NONBLOCK;
    	int support_keepalive = 1;
    
    	if (backlog == 0)
    		return NULL;
    
    	if (flags & LEV_OPT_CLOSE_ON_EXEC)
    		socktype |= EVUTIL_SOCK_CLOEXEC;
    
    	fd = evutil_socket_(family, socktype, 0);
    	if (fd == -1)
    		return NULL;
    
    #if defined(_WIN32) && defined(EVENT__HAVE_AFUNIX_H)
    	if (family == AF_UNIX && evutil_check_working_afunix_()) {
    		/* AF_UNIX socket can't set SO_KEEPALIVE option on Win10.
    		 * Avoid 10042 error.  */
    		support_keepalive = 0;
    	}
    #endif
    	if (support_keepalive) {
    		if (setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE, (void*)&on, sizeof(on))<0)
    			goto err;
    	}
    
    	if (flags & LEV_OPT_REUSEABLE) {
    		if (evutil_make_listen_socket_reuseable(fd) < 0)
    			goto err;
    	}
    
    	if (flags & LEV_OPT_REUSEABLE_PORT) {
    		if (evutil_make_listen_socket_reuseable_port(fd) < 0)
    			goto err;
    	}
    
    	if (flags & LEV_OPT_DEFERRED_ACCEPT) {
    		if (evutil_make_tcp_listen_socket_deferred(fd) < 0)
    			goto err;
    	}
    
    	if (flags & LEV_OPT_BIND_IPV6ONLY) {
    		if (evutil_make_listen_socket_ipv6only(fd) < 0)
    			goto err;
    	}
    
    	if (sa) {
    		if (bind(fd, sa, socklen)<0)
    			goto err;
    	}
    
    	listener = evconnlistener_new(base, cb, ptr, flags, backlog, fd);
    	if (!listener)
    		goto err;
    
    	return listener;
    err:
    	{
    		int saved_errno = EVUTIL_SOCKET_ERROR();
    		evutil_closesocket(fd);
    		if (saved_errno)
    			EVUTIL_SET_SOCKET_ERROR(saved_errno);
    		return NULL;
    	}
    }
    
    void
    evconnlistener_free(struct evconnlistener *lev)
    {
    	LOCK(lev);
    	lev->cb = NULL;
    	lev->errorcb = NULL;
    	if (lev->ops->shutdown)
    		lev->ops->shutdown(lev);
    	listener_decref_and_unlock(lev);
    }
    
    static void
    event_listener_destroy(struct evconnlistener *lev)
    {
    	struct evconnlistener_event *lev_e =
    	    EVUTIL_UPCAST(lev, struct evconnlistener_event, base);
    
    	event_del(&lev_e->listener);
    	if (lev->flags & LEV_OPT_CLOSE_ON_FREE)
    		evutil_closesocket(event_get_fd(&lev_e->listener));
    	event_debug_unassign(&lev_e->listener);
    }
    
    int
    evconnlistener_enable(struct evconnlistener *lev)
    {
    	int r;
    	LOCK(lev);
    	lev->enabled = 1;
    	if (lev->cb)
    		r = lev->ops->enable(lev);
    	else
    		r = 0;
    	UNLOCK(lev);
    	return r;
    }
    
    int
    evconnlistener_disable(struct evconnlistener *lev)
    {
    	int r;
    	LOCK(lev);
    	lev->enabled = 0;
    	r = lev->ops->disable(lev);
    	UNLOCK(lev);
    	return r;
    }
    
    static int
    event_listener_enable(struct evconnlistener *lev)
    {
    	struct evconnlistener_event *lev_e =
    	    EVUTIL_UPCAST(lev, struct evconnlistener_event, base);
    	return event_add(&lev_e->listener, NULL);
    }
    
    static int
    event_listener_disable(struct evconnlistener *lev)
    {
    	struct evconnlistener_event *lev_e =
    	    EVUTIL_UPCAST(lev, struct evconnlistener_event, base);
    	return event_del(&lev_e->listener);
    }
    
    evutil_socket_t
    evconnlistener_get_fd(struct evconnlistener *lev)
    {
    	evutil_socket_t fd;
    	LOCK(lev);
    	fd = lev->ops->getfd(lev);
    	UNLOCK(lev);
    	return fd;
    }
    
    static evutil_socket_t
    event_listener_getfd(struct evconnlistener *lev)
    {
    	struct evconnlistener_event *lev_e =
    	    EVUTIL_UPCAST(lev, struct evconnlistener_event, base);
    	return event_get_fd(&lev_e->listener);
    }
    
    struct event_base *
    evconnlistener_get_base(struct evconnlistener *lev)
    {
    	struct event_base *base;
    	LOCK(lev);
    	base = lev->ops->getbase(lev);
    	UNLOCK(lev);
    	return base;
    }
    
    static struct event_base *
    event_listener_getbase(struct evconnlistener *lev)
    {
    	struct evconnlistener_event *lev_e =
    	    EVUTIL_UPCAST(lev, struct evconnlistener_event, base);
    	return event_get_base(&lev_e->listener);
    }
    
    void
    evconnlistener_set_cb(struct evconnlistener *lev,
        evconnlistener_cb cb, void *arg)
    {
    	int enable = 0;
    	LOCK(lev);
    	if (lev->enabled && !lev->cb)
    		enable = 1;
    	lev->cb = cb;
    	lev->user_data = arg;
    	if (enable)
    		evconnlistener_enable(lev);
    	UNLOCK(lev);
    }
    
    void
    evconnlistener_set_error_cb(struct evconnlistener *lev,
        evconnlistener_errorcb errorcb)
    {
    	LOCK(lev);
    	lev->errorcb = errorcb;
    	UNLOCK(lev);
    }
    
    static void
    listener_read_cb(evutil_socket_t fd, short what, void *p)
    {
    	struct evconnlistener *lev = p;
    	int err;
    	evconnlistener_cb cb;
    	evconnlistener_errorcb errorcb;
    	void *user_data;
    	LOCK(lev);
    	while (1) {
    		struct sockaddr_storage ss;
    		ev_socklen_t socklen = sizeof(ss);
    		evutil_socket_t new_fd = evutil_accept4_(fd, (struct sockaddr*)&ss, &socklen, lev->accept4_flags);
    		if (new_fd < 0)
    			break;
    		if (socklen == 0) {
    			/* This can happen with some older linux kernels in
    			 * response to nmap. */
    			evutil_closesocket(new_fd);
    			continue;
    		}
    
    		if (lev->cb == NULL) {
    			evutil_closesocket(new_fd);
    			UNLOCK(lev);
    			return;
    		}
    		++lev->refcnt;
    		cb = lev->cb;
    		user_data = lev->user_data;
    		cb(lev, new_fd, (struct sockaddr*)&ss, (int)socklen,
    		    user_data);
    		if (lev->refcnt == 1) {
    			int freed = listener_decref_and_unlock(lev);
    			EVUTIL_ASSERT(freed);
    			return;
    		}
    		--lev->refcnt;
    		if (!lev->enabled) {
    			/* the callback could have disabled the listener */
    			UNLOCK(lev);
    			return;
    		}
    	}
    	err = evutil_socket_geterror(fd);
    	if (EVUTIL_ERR_ACCEPT_RETRIABLE(err)) {
    		UNLOCK(lev);
    		return;
    	}
    	if (lev->errorcb != NULL) {
    		++lev->refcnt;
    		errorcb = lev->errorcb;
    		user_data = lev->user_data;
    		errorcb(lev, user_data);
    		listener_decref_and_unlock(lev);
    	} else {
    		event_sock_warn(fd, "Error from accept() call");
    		UNLOCK(lev);
    	}
    }
    
    #ifdef _WIN32
    struct accepting_socket {
    	CRITICAL_SECTION lock;
    	struct event_overlapped overlapped;
    	SOCKET s;
    	int error;
    	struct event_callback deferred;
    	struct evconnlistener_iocp *lev;
    	ev_uint8_t buflen;
    	ev_uint8_t family;
    	unsigned free_on_cb:1;
    	char addrbuf[1];
    };
    
    static void accepted_socket_cb(struct event_overlapped *o, ev_uintptr_t key,
        ev_ssize_t n, int ok);
    static void accepted_socket_invoke_user_cb(struct event_callback *cb, void *arg);
    
    static void
    iocp_listener_event_add(struct evconnlistener_iocp *lev)
    {
    	if (lev->event_added)
    		return;
    
    	lev->event_added = 1;
    	event_base_add_virtual_(lev->event_base);
    }
    
    static void
    iocp_listener_event_del(struct evconnlistener_iocp *lev)
    {
    	if (!lev->event_added)
    		return;
    
    	lev->event_added = 0;
    	event_base_del_virtual_(lev->event_base);
    }
    
    static struct accepting_socket *
    new_accepting_socket(struct evconnlistener_iocp *lev, int family)
    {
    	struct accepting_socket *res;
    	int addrlen;
    	int buflen;
    
    	if (family == AF_INET)
    		addrlen = sizeof(struct sockaddr_in);
    	else if (family == AF_INET6)
    		addrlen = sizeof(struct sockaddr_in6);
    #ifdef EVENT__HAVE_AFUNIX_H
    	else if (family == AF_UNIX && evutil_check_working_afunix_())
    		addrlen = sizeof(struct sockaddr_un);
    #endif
    	else
    		return NULL;
    	buflen = (addrlen+16)*2;
    
    	res = mm_calloc(1,sizeof(struct accepting_socket)-1+buflen);
    	if (!res)
    		return NULL;
    
    	event_overlapped_init_(&res->overlapped, accepted_socket_cb);
    	res->s = EVUTIL_INVALID_SOCKET;
    	res->lev = lev;
    	res->buflen = buflen;
    	res->family = family;
    
    	event_deferred_cb_init_(&res->deferred,
    	    event_base_get_npriorities(lev->event_base) / 2,
    	    accepted_socket_invoke_user_cb, res);
    
    	InitializeCriticalSectionAndSpinCount(&res->lock, 1000);
    
    	return res;
    }
    
    static void
    free_and_unlock_accepting_socket(struct accepting_socket *as)
    {
    	/* requires lock. */
    	if (as->s != EVUTIL_INVALID_SOCKET)
    		closesocket(as->s);
    
    	LeaveCriticalSection(&as->lock);
    	DeleteCriticalSection(&as->lock);
    	mm_free(as);
    }
    
    static int
    start_accepting(struct accepting_socket *as)
    {
    	/* requires lock */
    	const struct win32_extension_fns *ext = event_get_win32_extension_fns_();
    	DWORD pending = 0;
    	SOCKET s = socket(as->family, SOCK_STREAM, 0);
    	int error = 0;
    
    	if (!as->lev->base.enabled)
    		return 0;
    
    	if (s == EVUTIL_INVALID_SOCKET) {
    		error = WSAGetLastError();
    		goto report_err;
    	}
    
    	/* XXXX It turns out we need to do this again later.  Does this call
    	 * have any effect? */
    	setsockopt(s, SOL_SOCKET, SO_UPDATE_ACCEPT_CONTEXT,
    	    (char *)&as->lev->fd, sizeof(&as->lev->fd));
    
    	if (!(as->lev->base.flags & LEV_OPT_LEAVE_SOCKETS_BLOCKING))
    		evutil_make_socket_nonblocking(s);
    
    	if (event_iocp_port_associate_(as->lev->port, s, 1) < 0) {
    		closesocket(s);
    		return -1;
    	}
    
    	as->s = s;
    
    	if (ext->AcceptEx(as->lev->fd, s, as->addrbuf, 0,
    		as->buflen/2, as->buflen/2, &pending, &as->overlapped.overlapped))
    	{
    		/* Immediate success! */
    		accepted_socket_cb(&as->overlapped, 1, 0, 1);
    	} else {
    		error = WSAGetLastError();
    		if (error != ERROR_IO_PENDING) {
    			goto report_err;
    		}
    	}
    
    	return 0;
    
    report_err:
    	as->error = error;
    	event_deferred_cb_schedule_(
    		as->lev->event_base,
    		&as->deferred);
    	return 0;
    }
    
    static void
    stop_accepting(struct accepting_socket *as)
    {
    	/* requires lock. */
    	SOCKET s = as->s;
    	as->s = EVUTIL_INVALID_SOCKET;
    	closesocket(s);
    }
    
    static void
    accepted_socket_invoke_user_cb(struct event_callback *dcb, void *arg)
    {
    	struct accepting_socket *as = arg;
    
    	struct sockaddr *sa_local=NULL, *sa_remote=NULL;
    	int socklen_local=0, socklen_remote=0;
    	const struct win32_extension_fns *ext = event_get_win32_extension_fns_();
    	struct evconnlistener *lev = &as->lev->base;
    	evutil_socket_t sock=-1;
    	void *data;
    	evconnlistener_cb cb=NULL;
    	evconnlistener_errorcb errorcb=NULL;
    	int error;
    
    	EVUTIL_ASSERT(ext->GetAcceptExSockaddrs);
    
    	LOCK(lev);
    	EnterCriticalSection(&as->lock);
    	if (as->free_on_cb) {
    		free_and_unlock_accepting_socket(as);
    		listener_decref_and_unlock(lev);
    		return;
    	}
    
    	++lev->refcnt;
    
    	error = as->error;
    	if (error) {
    		as->error = 0;
    		errorcb = lev->errorcb;
    	} else {
    		ext->GetAcceptExSockaddrs(
    			as->addrbuf, 0, as->buflen/2, as->buflen/2,
    			&sa_local, &socklen_local, &sa_remote,
    			&socklen_remote);
    		sock = as->s;
    		cb = lev->cb;
    		as->s = EVUTIL_INVALID_SOCKET;
    
    		/* We need to call this so getsockname, getpeername, and
    		 * shutdown work correctly on the accepted socket. */
    		/* XXXX handle error? */
    		setsockopt(sock, SOL_SOCKET, SO_UPDATE_ACCEPT_CONTEXT,
    		    (char *)&as->lev->fd, sizeof(&as->lev->fd));
    	}
    	data = lev->user_data;
    
    	LeaveCriticalSection(&as->lock);
    	UNLOCK(lev);
    
    	if (errorcb) {
    		WSASetLastError(error);
    		errorcb(lev, data);
    	} else if (cb) {
    		cb(lev, sock, sa_remote, socklen_remote, data);
    	}
    
    	LOCK(lev);
    	if (listener_decref_and_unlock(lev))
    		return;
    
    	EnterCriticalSection(&as->lock);
    	start_accepting(as);
    	LeaveCriticalSection(&as->lock);
    }
    
    static void
    accepted_socket_cb(struct event_overlapped *o, ev_uintptr_t key, ev_ssize_t n, int ok)
    {
    	struct accepting_socket *as =
    	    EVUTIL_UPCAST(o, struct accepting_socket, overlapped);
    
    	LOCK(&as->lev->base);
    	EnterCriticalSection(&as->lock);
    	if (ok) {
    		/* XXXX Don't do this if some EV_MT flag is set. */
    		event_deferred_cb_schedule_(
    			as->lev->event_base,
    			&as->deferred);
    		LeaveCriticalSection(&as->lock);
    	} else if (as->free_on_cb) {
    		struct evconnlistener *lev = &as->lev->base;
    		free_and_unlock_accepting_socket(as);
    		listener_decref_and_unlock(lev);
    		return;
    	} else if (as->s == EVUTIL_INVALID_SOCKET) {
    		/* This is okay; we were disabled by iocp_listener_disable. */
    		LeaveCriticalSection(&as->lock);
    	} else {
    		/* Some error on accept that we couldn't actually handle. */
    		BOOL ok;
    		DWORD transfer = 0, flags=0;
    		event_sock_warn(as->s, "Unexpected error on AcceptEx");
    		ok = WSAGetOverlappedResult(as->s, &o->overlapped,
    		    &transfer, FALSE, &flags);
    		if (ok) {
    			/* well, that was confusing! */
    			as->error = 1;
    		} else {
    			as->error = WSAGetLastError();
    		}
    		event_deferred_cb_schedule_(
    			as->lev->event_base,
    			&as->deferred);
    		LeaveCriticalSection(&as->lock);
    	}
    	UNLOCK(&as->lev->base);
    }
    
    static int
    iocp_listener_enable(struct evconnlistener *lev)
    {
    	int i;
    	struct evconnlistener_iocp *lev_iocp =
    	    EVUTIL_UPCAST(lev, struct evconnlistener_iocp, base);
    
    	LOCK(lev);
    	iocp_listener_event_add(lev_iocp);
    	for (i = 0; i < lev_iocp->n_accepting; ++i) {
    		struct accepting_socket *as = lev_iocp->accepting[i];
    		if (!as)
    			continue;
    		EnterCriticalSection(&as->lock);
    		if (!as->free_on_cb && as->s == EVUTIL_INVALID_SOCKET)
    			start_accepting(as);
    		LeaveCriticalSection(&as->lock);
    	}
    	UNLOCK(lev);
    	return 0;
    }
    
    static int
    iocp_listener_disable_impl(struct evconnlistener *lev, int shutdown)
    {
    	int i;
    	struct evconnlistener_iocp *lev_iocp =
    	    EVUTIL_UPCAST(lev, struct evconnlistener_iocp, base);
    
    	LOCK(lev);
    	iocp_listener_event_del(lev_iocp);
    	for (i = 0; i < lev_iocp->n_accepting; ++i) {
    		struct accepting_socket *as = lev_iocp->accepting[i];
    		if (!as)
    			continue;
    		EnterCriticalSection(&as->lock);
    		if (!as->free_on_cb && as->s != EVUTIL_INVALID_SOCKET) {
    			if (shutdown)
    				as->free_on_cb = 1;
    			stop_accepting(as);
    		}
    		LeaveCriticalSection(&as->lock);
    	}
    
    	if (shutdown && lev->flags & LEV_OPT_CLOSE_ON_FREE)
    		evutil_closesocket(lev_iocp->fd);
    
    	UNLOCK(lev);
    	return 0;
    }
    
    static int
    iocp_listener_disable(struct evconnlistener *lev)
    {
    	return iocp_listener_disable_impl(lev,0);
    }
    
    static void
    iocp_listener_destroy(struct evconnlistener *lev)
    {
    	struct evconnlistener_iocp *lev_iocp =
    	    EVUTIL_UPCAST(lev, struct evconnlistener_iocp, base);
    
    	if (! lev_iocp->shutting_down) {
    		lev_iocp->shutting_down = 1;
    		iocp_listener_disable_impl(lev,1);
    	}
    
    }
    
    static evutil_socket_t
    iocp_listener_getfd(struct evconnlistener *lev)
    {
    	struct evconnlistener_iocp *lev_iocp =
    	    EVUTIL_UPCAST(lev, struct evconnlistener_iocp, base);
    	return lev_iocp->fd;
    }
    static struct event_base *
    iocp_listener_getbase(struct evconnlistener *lev)
    {
    	struct evconnlistener_iocp *lev_iocp =
    	    EVUTIL_UPCAST(lev, struct evconnlistener_iocp, base);
    	return lev_iocp->event_base;
    }
    
    static const struct evconnlistener_ops evconnlistener_iocp_ops = {
    	iocp_listener_enable,
    	iocp_listener_disable,
    	iocp_listener_destroy,
    	iocp_listener_destroy, /* shutdown */
    	iocp_listener_getfd,
    	iocp_listener_getbase
    };
    
    /* XXX define some way to override this. */
    #define N_SOCKETS_PER_LISTENER 4
    
    struct evconnlistener *
    evconnlistener_new_async(struct event_base *base,
        evconnlistener_cb cb, void *ptr, unsigned flags, int backlog,
        evutil_socket_t fd)
    {
    	struct sockaddr_storage ss;
    	int socklen = sizeof(ss);
    	struct evconnlistener_iocp *lev;
    	int i;
    
    	flags |= LEV_OPT_THREADSAFE;
    
    	if (!base || !event_base_get_iocp_(base))
    		goto err;
    
    	/* XXXX duplicate code */
    	if (backlog > 0) {
    		if (listen(fd, backlog) < 0)
    			goto err;
    	} else if (backlog < 0) {
    		if (listen(fd, 128) < 0)
    			goto err;
    	}
    	if (getsockname(fd, (struct sockaddr*)&ss, &socklen)) {
    		event_sock_warn(fd, "getsockname");
    		goto err;
    	}
    	lev = mm_calloc(1, sizeof(struct evconnlistener_iocp));
    	if (!lev) {
    		event_warn("calloc");
    		goto err;
    	}
    	lev->base.ops = &evconnlistener_iocp_ops;
    	lev->base.cb = cb;
    	lev->base.user_data = ptr;
    	lev->base.flags = flags;
    	lev->base.refcnt = 1;
    	lev->base.enabled = 1;
    
    	lev->port = event_base_get_iocp_(base);
    	lev->fd = fd;
    	lev->event_base = base;
    
    
    	if (event_iocp_port_associate_(lev->port, fd, 1) < 0)
    		goto err_free_lev;
    
    	EVTHREAD_ALLOC_LOCK(lev->base.lock, EVTHREAD_LOCKTYPE_RECURSIVE);
    
    	lev->n_accepting = N_SOCKETS_PER_LISTENER;
    	lev->accepting = mm_calloc(lev->n_accepting,
    	    sizeof(struct accepting_socket *));
    	if (!lev->accepting) {
    		event_warn("calloc");
    		goto err_delete_lock;
    	}
    	for (i = 0; i < lev->n_accepting; ++i) {
    		lev->accepting[i] = new_accepting_socket(lev, ss.ss_family);
    		if (!lev->accepting[i]) {
    			event_warnx("Couldn't create accepting socket");
    			goto err_free_accepting;
    		}
    		if (cb && start_accepting(lev->accepting[i]) < 0) {
    			event_warnx("Couldn't start accepting on socket");
    			EnterCriticalSection(&lev->accepting[i]->lock);
    			free_and_unlock_accepting_socket(lev->accepting[i]);
    			goto err_free_accepting;
    		}
    		++lev->base.refcnt;
    	}
    
    	iocp_listener_event_add(lev);
    
    	return &lev->base;
    
    err_free_accepting:
    	mm_free(lev->accepting);
    	/* XXXX free the other elements. */
    err_delete_lock:
    	EVTHREAD_FREE_LOCK(lev->base.lock, EVTHREAD_LOCKTYPE_RECURSIVE);
    err_free_lev:
    	mm_free(lev);
    err:
    	/* Don't close the fd, it is caller's responsibility. */
    	return NULL;
    }
    
    #endif