unbound/util/winsock_event.h

   1 /*
   2  * util/winsock_event.h - unbound event handling for winsock on windows
   3  *
   4  * Copyright (c) 2008, NLnet Labs. All rights reserved.
   5  *
   6  * This software is open source.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  *
  12  * Redistributions of source code must retain the above copyright notice,
  13  * this list of conditions and the following disclaimer.
  14  *
  15  * Redistributions in binary form must reproduce the above copyright notice,
  16  * this list of conditions and the following disclaimer in the documentation
  17  * and/or other materials provided with the distribution.
  18  *
  19  * Neither the name of the NLNET LABS nor the names of its contributors may
  20  * be used to endorse or promote products derived from this software without
  21  * specific prior written permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  24  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  25  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  26  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  27  * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  28  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
  29  * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  30  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
  31  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  32  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  33  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  34  */
  35
  36 /**
  37  * \file
  38  *
  39  * This file contains interface functions with the WinSock2 API on Windows.
  40  * It uses the winsock WSAWaitForMultipleEvents interface on a number of
  41  * sockets.
  42  *
  43  * Note that windows can only wait for max 64 events at one time.
  44  *
  45  * Also, file descriptors cannot be waited for.
  46  *
  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.
  50  *
  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.
  65  *
  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.
  68  *
  69  * Additionally, TCP accept sockets get special event support.
  70  *
  71  * Socket numbers are not starting small, they can be any number (say 33060).
  72  * Therefore, bitmaps are not used, but arrays.
  73  *
  74  * on winsock, you must use recv() and send() for TCP reads and writes,
  75  * not read() and write(), those work only on files.
  76  *
  77  * Also fseek and fseeko do not work if a FILE is not fopen-ed in binary mode.
  78  *
  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.
  82  */
  83
  84 #ifndef UTIL_WINSOCK_EVENT_H
  85 #define UTIL_WINSOCK_EVENT_H
  86
  87 #ifdef USE_WINSOCK
  88
  89 #ifndef HAVE_EVENT_BASE_FREE
  90 #define HAVE_EVENT_BASE_FREE
  91 #endif
  92
  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
 107
 108 /** event timeout */
 109 #define EV_TIMEOUT      0x01
 110 /** event fd readable */
 111 #define EV_READ         0x02
 112 /** event fd writable */
 113 #define EV_WRITE        0x04
 114 /** event signal */
 115 #define EV_SIGNAL       0x08
 116 /** event must persist */
 117 #define EV_PERSIST      0x10
 118
 119 /* needs our redblack tree */
 120 #include "rbtree.h"
 121
 122 /** max number of signals to support */
 123 #define MAX_SIG 32
 124
 125 /** The number of items that the winsock event handler can service.
 126  * Windows cannot handle more anyway */
 127 #define WSK_MAX_ITEMS 64
 128
 129 /**
 130  * event base for winsock event handler
 131  */
 132 struct event_base
 133 {
 134         /** sorted by timeout (absolute), ptr */
 135         rbtree_t* times;
 136         /** array (first part in use) of handles to work on */
 137         struct event** items;
 138         /** number of items in use in array */
 139         int max;
 140         /** capacity of array, size of array in items */
 141         int cap;
 142         /** array of 0 - maxsig of ptr to event for it */
 143         struct event** signals;
 144         /** if we need to exit */
 145         int need_to_exit;
 146         /** where to store time in seconds */
 147         time_t* time_secs;
 148         /** where to store time in microseconds */
 149         struct timeval* time_tv;
 150         /**
 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.
 155          */
 156         int tcp_stickies;
 157         /**
 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.
 161          */
 162         int tcp_reinvigorated;
 163         /** The list of events that is currently being processed. */
 164         WSAEVENT waitfor[WSK_MAX_ITEMS];
 165 };
 166
 167 /**
 168  * Event structure. Has some of the event elements.
 169  */
 170 struct event {
 171         /** node in timeout rbtree */
 172         rbnode_t node;
 173         /** is event already added */
 174         int added;
 175
 176         /** event base it belongs to */
 177         struct event_base *ev_base;
 178         /** fd to poll or -1 for timeouts. signal number for sigs. */
 179         int ev_fd;
 180         /** what events this event is interested in, see EV_.. above. */
 181         short ev_events;
 182         /** timeout value */
 183         struct timeval ev_timeout;
 184
 185         /** callback to call: fd, eventbits, userarg */
 186         void (*ev_callback)(int, short, void *);
 187         /** callback user arg */
 188         void *ev_arg;
 189
 190         /* ----- nonpublic part, for winsock_event only ----- */
 191         /** index of this event in the items array (if added) */
 192         int idx;
 193         /** the event handle to wait for new events to become ready */
 194         WSAEVENT hEvent;
 195         /** true if this filedes is a TCP socket and needs special attention */
 196         int is_tcp;
 197         /** remembered EV_ values */
 198         short old_events;
 199         /** should remembered EV_ values be used for TCP streams.
 200          * Reset after WOULDBLOCK is signaled using the function. */
 201         int stick_events;
 202
 203         /** true if this event is a signaling WSAEvent by the user.
 204          * User created and user closed WSAEvent. Only signaled/unsigneled,
 205          * no read/write/distinctions needed. */
 206         int is_signal;
 207         /** used during callbacks to see which events were just checked */
 208         int just_checked;
 209 };
 210
 211 /** create event base */
 212 void *event_init(time_t* time_secs, struct timeval* time_tv);
 213 /** get version */
 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 *);
 225
 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 *);
 232
 233 #define evtimer_add(ev, tv)             event_add(ev, tv)
 234 #define evtimer_del(ev)                 event_del(ev)
 235
 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 *);
 245
 246 /** compare events in tree, based on timevalue, ptr for uniqueness */
 247 int mini_ev_cmp(const void* a, const void* b);
 248
 249 /**
 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.
 254  */
 255 void winsock_tcp_wouldblock(struct event* ev, int eventbit);
 256
 257 /**
 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.
 268  */
 269 int winsock_register_wsaevent(struct event_base* base, struct event* ev,
 270         WSAEVENT wsaevent, void (*cb)(int, short, void*), void* arg);
 271
 272 /**
 273  * Unregister a wsaevent. User has to close the WSAEVENT itself.
 274  * @param ev: event data storage.
 275  */
 276 void winsock_unregister_wsaevent(struct event* ev);
 277
 278 #endif /* USE_WINSOCK */
 279 #endif /* UTIL_WINSOCK_EVENT_H */