2 * util/winsock_event.h - unbound event handling for winsock on windows
4 * Copyright (c) 2008, NLnet Labs. All rights reserved.
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39 * This file contains interface functions with the WinSock2 API on Windows.
40 * It uses the winsock WSAWaitForMultipleEvents interface on a number of
43 * Note that windows can only wait for max 64 events at one time.
45 * Also, file descriptors cannot be waited for.
47 * Named pipes are not easily available (and are not usable in select() ).
48 * For interprocess communication, it is possible to wait for a hEvent to
49 * be signaled by another thread.
51 * When a socket becomes readable, then it will not be flagged as
52 * readable again until you have gotten WOULDBLOCK from a recv routine.
53 * That means the event handler must store the readability (edge notify)
54 * and process the incoming data until it blocks.
55 * The function performing recv then has to inform the event handler that
56 * the socket has blocked, and the event handler can mark it as such.
57 * Thus, this file transforms the edge notify from windows to a level notify
58 * that is compatible with UNIX.
59 * The WSAEventSelect page says that it does do level notify, as long
60 * as you call a recv/write/accept at least once when it is signalled.
61 * This last bit is not true, even though documented in server2008 api docs
62 * from microsoft, it does not happen at all. Instead you have to test for
63 * WSAEWOULDBLOCK on a tcp stream, and only then retest the socket.
64 * And before that remember the previous result as still valid.
66 * To stay 'fair', instead of emptying a socket completely, the event handler
67 * can test the other (marked as blocking) sockets for new events.
69 * Additionally, TCP accept sockets get special event support.
71 * Socket numbers are not starting small, they can be any number (say 33060).
72 * Therefore, bitmaps are not used, but arrays.
74 * on winsock, you must use recv() and send() for TCP reads and writes,
75 * not read() and write(), those work only on files.
77 * Also fseek and fseeko do not work if a FILE is not fopen-ed in binary mode.
79 * When under a high load windows gives out lots of errors, from recvfrom
80 * on udp sockets for example (WSAECONNRESET). Even though the udp socket
81 * has no connection per se.
84 #ifndef UTIL_WINSOCK_EVENT_H
85 #define UTIL_WINSOCK_EVENT_H
89 #ifndef HAVE_EVENT_BASE_FREE
90 #define HAVE_EVENT_BASE_FREE
93 /* redefine the calls to different names so that there is no name
94 * collision with other code that uses libevent names. (that uses libunbound)*/
95 #define event_init winsockevent_init
96 #define event_get_version winsockevent_get_version
97 #define event_get_method winsockevent_get_method
98 #define event_base_dispatch winsockevent_base_dispatch
99 #define event_base_loopexit winsockevent_base_loopexit
100 #define event_base_free winsockevent_base_free
101 #define event_set winsockevent_set
102 #define event_base_set winsockevent_base_set
103 #define event_add winsockevent_add
104 #define event_del winsockevent_del
105 #define signal_add winsocksignal_add
106 #define signal_del winsocksignal_del
109 #define EV_TIMEOUT 0x01
110 /** event fd readable */
112 /** event fd writable */
113 #define EV_WRITE 0x04
115 #define EV_SIGNAL 0x08
116 /** event must persist */
117 #define EV_PERSIST 0x10
119 /* needs our redblack tree */
122 /** max number of signals to support */
125 /** The number of items that the winsock event handler can service.
126 * Windows cannot handle more anyway */
127 #define WSK_MAX_ITEMS 64
130 * event base for winsock event handler
134 /** sorted by timeout (absolute), ptr */
136 /** array (first part in use) of handles to work on */
137 struct event** items;
138 /** number of items in use in array */
140 /** capacity of array, size of array in items */
142 /** array of 0 - maxsig of ptr to event for it */
143 struct event** signals;
144 /** if we need to exit */
146 /** where to store time in seconds */
148 /** where to store time in microseconds */
149 struct timeval* time_tv;
151 * TCP streams have sticky events to them, these are not
152 * reported by the windows event system anymore, we have to
153 * keep reporting those events as present until wouldblock() is
154 * signalled by the handler back to use.
158 * should next cycle process reinvigorated stickies,
159 * these are stickies that have been stored, but due to a new
160 * event_add a sudden interest in the event has incepted.
162 int tcp_reinvigorated;
163 /** The list of events that is currently being processed. */
164 WSAEVENT waitfor[WSK_MAX_ITEMS];
168 * Event structure. Has some of the event elements.
171 /** node in timeout rbtree */
173 /** is event already added */
176 /** event base it belongs to */
177 struct event_base *ev_base;
178 /** fd to poll or -1 for timeouts. signal number for sigs. */
180 /** what events this event is interested in, see EV_.. above. */
183 struct timeval ev_timeout;
185 /** callback to call: fd, eventbits, userarg */
186 void (*ev_callback)(int, short, void *);
187 /** callback user arg */
190 /* ----- nonpublic part, for winsock_event only ----- */
191 /** index of this event in the items array (if added) */
193 /** the event handle to wait for new events to become ready */
195 /** true if this filedes is a TCP socket and needs special attention */
197 /** remembered EV_ values */
199 /** should remembered EV_ values be used for TCP streams.
200 * Reset after WOULDBLOCK is signaled using the function. */
203 /** true if this event is a signaling WSAEvent by the user.
204 * User created and user closed WSAEvent. Only signaled/unsignaled,
205 * no read/write/distinctions needed. */
207 /** used during callbacks to see which events were just checked */
211 /** create event base */
212 void *event_init(time_t* time_secs, struct timeval* time_tv);
214 const char *event_get_version(void);
215 /** get polling method (select,epoll) */
216 const char *event_get_method(void);
217 /** run select in a loop */
218 int event_base_dispatch(struct event_base *);
219 /** exit that loop */
220 int event_base_loopexit(struct event_base *, struct timeval *);
221 /** free event base. Free events yourself */
222 void event_base_free(struct event_base *);
223 /** set content of event */
224 void event_set(struct event *, int, short, void (*)(int, short, void *), void *);
226 /** add event to a base. You *must* call this for every event. */
227 int event_base_set(struct event_base *, struct event *);
228 /** add event to make it active. You may not change it with event_set anymore */
229 int event_add(struct event *, struct timeval *);
230 /** remove event. You may change it again */
231 int event_del(struct event *);
233 #define evtimer_add(ev, tv) event_add(ev, tv)
234 #define evtimer_del(ev) event_del(ev)
236 /* uses different implementation. Cannot mix fd/timeouts and signals inside
237 * the same struct event. create several event structs for that. */
238 /** install signal handler */
239 int signal_add(struct event *, struct timeval *);
240 /** set signal event contents */
241 #define signal_set(ev, x, cb, arg) \
242 event_set(ev, x, EV_SIGNAL|EV_PERSIST, cb, arg)
243 /** remove signal handler */
244 int signal_del(struct event *);
246 /** compare events in tree, based on timevalue, ptr for uniqueness */
247 int mini_ev_cmp(const void* a, const void* b);
250 * Routine for windows only, where the handling layer can signal that
251 * a TCP stream encountered WSAEWOULDBLOCK for a stream and thus needs
252 * retesting the event.
253 * Pass if EV_READ or EV_WRITE gave wouldblock.
255 void winsock_tcp_wouldblock(struct event* ev, int eventbit);
258 * Routine for windows only. where you pass a signal WSAEvent that
259 * you wait for. When the event is signaled, the callback gets called.
260 * The callback has to WSAResetEvent to disable the signal.
261 * @param base: the event base.
262 * @param ev: the event structure for data storage
263 * can be passed uninitialised.
264 * @param wsaevent: the WSAEvent that gets signaled.
265 * @param cb: callback routine.
266 * @param arg: user argument to callback routine.
267 * @return false on error.
269 int winsock_register_wsaevent(struct event_base* base, struct event* ev,
270 WSAEVENT wsaevent, void (*cb)(int, short, void*), void* arg);
273 * Unregister a wsaevent. User has to close the WSAEVENT itself.
274 * @param ev: event data storage.
276 void winsock_unregister_wsaevent(struct event* ev);
278 #endif /* USE_WINSOCK */
279 #endif /* UTIL_WINSOCK_EVENT_H */