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