/*
* util/winsock_event.h - unbound event handling for winsock on windows
*
* Copyright (c) 2008, NLnet Labs. All rights reserved.
*
* This software is open source.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* 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.
*
* Neither the name of the NLNET LABS nor the names of its contributors may
* be used to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "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 COPYRIGHT
* HOLDER OR CONTRIBUTORS 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.
*/
/**
* \file
*
* This file contains interface functions with the WinSock2 API on Windows.
* It uses the winsock WSAWaitForMultipleEvents interface on a number of
* sockets.
*
* Note that windows can only wait for max 64 events at one time.
*
* Also, file descriptors cannot be waited for.
*
* Named pipes are not easily available (and are not usable in select() ).
* For interprocess communication, it is possible to wait for a hEvent to
* be signaled by another thread.
*
* When a socket becomes readable, then it will not be flagged as
* readable again until you have gotten WOULDBLOCK from a recv routine.
* That means the event handler must store the readability (edge notify)
* and process the incoming data until it blocks.
* The function performing recv then has to inform the event handler that
* the socket has blocked, and the event handler can mark it as such.
* Thus, this file transforms the edge notify from windows to a level notify
* that is compatible with UNIX.
* The WSAEventSelect page says that it does do level notify, as long
* as you call a recv/write/accept at least once when it is signalled.
* This last bit is not true, even though documented in server2008 api docs
* from microsoft, it does not happen at all. Instead you have to test for
* WSAEWOULDBLOCK on a tcp stream, and only then retest the socket.
* And before that remember the previous result as still valid.
*
* To stay 'fair', instead of emptying a socket completely, the event handler
* can test the other (marked as blocking) sockets for new events.
*
* Additionally, TCP accept sockets get special event support.
*
* Socket numbers are not starting small, they can be any number (say 33060).
* Therefore, bitmaps are not used, but arrays.
*
* on winsock, you must use recv() and send() for TCP reads and writes,
* not read() and write(), those work only on files.
*
* Also fseek and fseeko do not work if a FILE is not fopen-ed in binary mode.
*
* When under a high load windows gives out lots of errors, from recvfrom
* on udp sockets for example (WSAECONNRESET). Even though the udp socket
* has no connection per se.
*/
#ifndef UTIL_WINSOCK_EVENT_H
#define UTIL_WINSOCK_EVENT_H
#ifdef USE_WINSOCK
#ifndef HAVE_EVENT_BASE_FREE
#define HAVE_EVENT_BASE_FREE
#endif
/* redefine the calls to different names so that there is no name
* collision with other code that uses libevent names. (that uses libunbound)*/
#define event_init winsockevent_init
#define event_get_version winsockevent_get_version
#define event_get_method winsockevent_get_method
#define event_base_dispatch winsockevent_base_dispatch
#define event_base_loopexit winsockevent_base_loopexit
#define event_base_free winsockevent_base_free
#define event_set winsockevent_set
#define event_base_set winsockevent_base_set
#define event_add winsockevent_add
#define event_del winsockevent_del
#define signal_add winsocksignal_add
#define signal_del winsocksignal_del
/** event timeout */
#define EV_TIMEOUT 0x01
/** event fd readable */
#define EV_READ 0x02
/** event fd writable */
#define EV_WRITE 0x04
/** event signal */
#define EV_SIGNAL 0x08
/** event must persist */
#define EV_PERSIST 0x10
/* needs our redblack tree */
#include "rbtree.h"
/** max number of signals to support */
#define MAX_SIG 32
/** The number of items that the winsock event handler can service.
* Windows cannot handle more anyway */
#define WSK_MAX_ITEMS 64
/**
* event base for winsock event handler
*/
struct event_base
{
/** sorted by timeout (absolute), ptr */
rbtree_t* times;
/** array (first part in use) of handles to work on */
struct event** items;
/** number of items in use in array */
int max;
/** capacity of array, size of array in items */
int cap;
/** array of 0 - maxsig of ptr to event for it */
struct event** signals;
/** if we need to exit */
int need_to_exit;
/** where to store time in seconds */
time_t* time_secs;
/** where to store time in microseconds */
struct timeval* time_tv;
/**
* TCP streams have sticky events to them, these are not
* reported by the windows event system anymore, we have to
* keep reporting those events as present until wouldblock() is
* signalled by the handler back to use.
*/
int tcp_stickies;
/**
* should next cycle process reinvigorated stickies,
* these are stickies that have been stored, but due to a new
* event_add a sudden interest in the event has incepted.
*/
int tcp_reinvigorated;
/** The list of events that is currently being processed. */
WSAEVENT waitfor[WSK_MAX_ITEMS];
};
/**
* Event structure. Has some of the event elements.
*/
struct event {
/** node in timeout rbtree */
rbnode_t node;
/** is event already added */
int added;
/** event base it belongs to */
struct event_base *ev_base;
/** fd to poll or -1 for timeouts. signal number for sigs. */
int ev_fd;
/** what events this event is interested in, see EV_.. above. */
short ev_events;
/** timeout value */
struct timeval ev_timeout;
/** callback to call: fd, eventbits, userarg */
void (*ev_callback)(int, short, void *);
/** callback user arg */
void *ev_arg;
/* ----- nonpublic part, for winsock_event only ----- */
/** index of this event in the items array (if added) */
int idx;
/** the event handle to wait for new events to become ready */
WSAEVENT hEvent;
/** true if this filedes is a TCP socket and needs special attention */
int is_tcp;
/** remembered EV_ values */
short old_events;
/** should remembered EV_ values be used for TCP streams.
* Reset after WOULDBLOCK is signaled using the function. */
int stick_events;
/** true if this event is a signaling WSAEvent by the user.
* User created and user closed WSAEvent. Only signaled/unsignaled,
* no read/write/distinctions needed. */
int is_signal;
/** used during callbacks to see which events were just checked */
int just_checked;
};
/** create event base */
void *event_init(time_t* time_secs, struct timeval* time_tv);
/** get version */
const char *event_get_version(void);
/** get polling method (select,epoll) */
const char *event_get_method(void);
/** run select in a loop */
int event_base_dispatch(struct event_base *);
/** exit that loop */
int event_base_loopexit(struct event_base *, struct timeval *);
/** free event base. Free events yourself */
void event_base_free(struct event_base *);
/** set content of event */
void event_set(struct event *, int, short, void (*)(int, short, void *), void *);
/** add event to a base. You *must* call this for every event. */
int event_base_set(struct event_base *, struct event *);
/** add event to make it active. You may not change it with event_set anymore */
int event_add(struct event *, struct timeval *);
/** remove event. You may change it again */
int event_del(struct event *);
#define evtimer_add(ev, tv) event_add(ev, tv)
#define evtimer_del(ev) event_del(ev)
/* uses different implementation. Cannot mix fd/timeouts and signals inside
* the same struct event. create several event structs for that. */
/** install signal handler */
int signal_add(struct event *, struct timeval *);
/** set signal event contents */
#define signal_set(ev, x, cb, arg) \
event_set(ev, x, EV_SIGNAL|EV_PERSIST, cb, arg)
/** remove signal handler */
int signal_del(struct event *);
/** compare events in tree, based on timevalue, ptr for uniqueness */
int mini_ev_cmp(const void* a, const void* b);
/**
* Routine for windows only, where the handling layer can signal that
* a TCP stream encountered WSAEWOULDBLOCK for a stream and thus needs
* retesting the event.
* Pass if EV_READ or EV_WRITE gave wouldblock.
*/
void winsock_tcp_wouldblock(struct event* ev, int eventbit);
/**
* Routine for windows only. where you pass a signal WSAEvent that
* you wait for. When the event is signaled, the callback gets called.
* The callback has to WSAResetEvent to disable the signal.
* @param base: the event base.
* @param ev: the event structure for data storage
* can be passed uninitialised.
* @param wsaevent: the WSAEvent that gets signaled.
* @param cb: callback routine.
* @param arg: user argument to callback routine.
* @return false on error.
*/
int winsock_register_wsaevent(struct event_base* base, struct event* ev,
WSAEVENT wsaevent, void (*cb)(int, short, void*), void* arg);
/**
* Unregister a wsaevent. User has to close the WSAEVENT itself.
* @param ev: event data storage.
*/
void winsock_unregister_wsaevent(struct event* ev);
#endif /* USE_WINSOCK */
#endif /* UTIL_WINSOCK_EVENT_H */
