File: winsock_event.h

package info (click to toggle)
unbound 1.6.0-2~bpo8%2B1
  • links: PTS, VCS
  • area: main
  • in suites: jessie-backports
  • size: 20,444 kB
  • sloc: ansic: 79,862; sh: 5,040; yacc: 1,900; makefile: 1,315; python: 1,302; perl: 141
file content (279 lines) | stat: -rw-r--r-- 10,425 bytes parent folder | download | duplicates (2)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
/*
 * 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 */