1/*
2 * Copyright (c) 2000-2007 Niels Provos <provos@citi.umich.edu>
3 * Copyright (c) 2007-2012 Niels Provos and Nick Mathewson
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. The name of the author may not be used to endorse or promote products
14 * derived from this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 */
27#ifndef EVENT2_BUFFEREVENT_H_INCLUDED_
28#define EVENT2_BUFFEREVENT_H_INCLUDED_
29
30/**
31 @file event2/bufferevent.h
32
33 Functions for buffering data for network sending or receiving. Bufferevents
34 are higher level than evbuffers: each has an underlying evbuffer for reading
35 and one for writing, and callbacks that are invoked under certain
36 circumstances.
37
38 A bufferevent provides input and output buffers that get filled and
39 drained automatically. The user of a bufferevent no longer deals
40 directly with the I/O, but instead is reading from input and writing
41 to output buffers.
42
43 Once initialized, the bufferevent structure can be used repeatedly
44 with bufferevent_enable() and bufferevent_disable().
45
46 When reading is enabled, the bufferevent will try to read from the
47 file descriptor onto its input buffer, and call the read callback.
48 When writing is enabled, the bufferevent will try to write data onto its
49 file descriptor when the output buffer has enough data, and call the write
50 callback when the output buffer is sufficiently drained.
51
52 Bufferevents come in several flavors, including:
53
54 <dl>
55 <dt>Socket-based bufferevents</dt>
56 <dd>A bufferevent that reads and writes data onto a network
57 socket. Created with bufferevent_socket_new().</dd>
58
59 <dt>Paired bufferevents</dt>
60 <dd>A pair of bufferevents that send and receive data to one
61 another without touching the network. Created with
62 bufferevent_pair_new().</dd>
63
64 <dt>Filtering bufferevents</dt>
65 <dd>A bufferevent that transforms data, and sends or receives it
66 over another underlying bufferevent. Created with
67 bufferevent_filter_new().</dd>
68
69 <dt>SSL-backed bufferevents</dt>
70 <dd>A bufferevent that uses the openssl library to send and
71 receive data over an encrypted connection. Created with
72 bufferevent_openssl_socket_new() or
73 bufferevent_openssl_filter_new().</dd>
74 </dl>
75 */
76
77#include <event2/visibility.h>
78
79#ifdef __cplusplus
80extern "C" {
81#endif
82
83#include <event2/event-config.h>
84#ifdef EVENT__HAVE_SYS_TYPES_H
85#include <sys/types.h>
86#endif
87#ifdef EVENT__HAVE_SYS_TIME_H
88#include <sys/time.h>
89#endif
90
91/* For int types. */
92#include <event2/util.h>
93
94/** @name Bufferevent event codes
95
96 These flags are passed as arguments to a bufferevent's event callback.
97
98 @{
99*/
100#define BEV_EVENT_READING 0x01 /**< error encountered while reading */
101#define BEV_EVENT_WRITING 0x02 /**< error encountered while writing */
102#define BEV_EVENT_EOF 0x10 /**< eof file reached */
103#define BEV_EVENT_ERROR 0x20 /**< unrecoverable error encountered */
104#define BEV_EVENT_TIMEOUT 0x40 /**< user-specified timeout reached */
105#define BEV_EVENT_CONNECTED 0x80 /**< connect operation finished. */
106/**@}*/
107
108/**
109 An opaque type for handling buffered IO
110
111 @see event2/bufferevent.h
112 */
113struct bufferevent
114#ifdef EVENT_IN_DOXYGEN_
115{}
116#endif
117;
118struct event_base;
119struct evbuffer;
120struct sockaddr;
121
122/**
123 A read or write callback for a bufferevent.
124
125 The read callback is triggered when new data arrives in the input
126 buffer and the amount of readable data exceed the low watermark
127 which is 0 by default.
128
129 The write callback is triggered if the write buffer has been
130 exhausted or fell below its low watermark.
131
132 @param bev the bufferevent that triggered the callback
133 @param ctx the user-specified context for this bufferevent
134 */
135typedef void (*bufferevent_data_cb)(struct bufferevent *bev, void *ctx);
136
137/**
138 An event/error callback for a bufferevent.
139
140 The event callback is triggered if either an EOF condition or another
141 unrecoverable error was encountered.
142
143 For bufferevents with deferred callbacks, this is a bitwise OR of all errors
144 that have happened on the bufferevent since the last callback invocation.
145
146 @param bev the bufferevent for which the error condition was reached
147 @param what a conjunction of flags: BEV_EVENT_READING or BEV_EVENT_WRITING
148 to indicate if the error was encountered on the read or write path,
149 and one of the following flags: BEV_EVENT_EOF, BEV_EVENT_ERROR,
150 BEV_EVENT_TIMEOUT, BEV_EVENT_CONNECTED.
151
152 @param ctx the user-specified context for this bufferevent
153*/
154typedef void (*bufferevent_event_cb)(struct bufferevent *bev, short what, void *ctx);
155
156/** Options that can be specified when creating a bufferevent */
157enum bufferevent_options {
158 /** If set, we close the underlying file
159 * descriptor/bufferevent/whatever when this bufferevent is freed. */
160 BEV_OPT_CLOSE_ON_FREE = (1<<0),
161
162 /** If set, and threading is enabled, operations on this bufferevent
163 * are protected by a lock */
164 BEV_OPT_THREADSAFE = (1<<1),
165
166 /** If set, callbacks are run deferred in the event loop. */
167 BEV_OPT_DEFER_CALLBACKS = (1<<2),
168
169 /** If set, callbacks are executed without locks being held on the
170 * bufferevent. This option currently requires that
171 * BEV_OPT_DEFER_CALLBACKS also be set; a future version of Libevent
172 * might remove the requirement.*/
173 BEV_OPT_UNLOCK_CALLBACKS = (1<<3)
174};
175
176/**
177 Create a new socket bufferevent over an existing socket.
178
179 @param base the event base to associate with the new bufferevent.
180 @param fd the file descriptor from which data is read and written to.
181 This file descriptor is not allowed to be a pipe(2).
182 It is safe to set the fd to -1, so long as you later
183 set it with bufferevent_setfd or bufferevent_socket_connect().
184 @param options Zero or more BEV_OPT_* flags
185 @return a pointer to a newly allocated bufferevent struct, or NULL if an
186 error occurred
187 @see bufferevent_free()
188 */
189EVENT2_EXPORT_SYMBOL
190struct bufferevent *bufferevent_socket_new(struct event_base *base, evutil_socket_t fd, int options);
191
192/**
193 Launch a connect() attempt with a socket-based bufferevent.
194
195 When the connect succeeds, the eventcb will be invoked with
196 BEV_EVENT_CONNECTED set.
197
198 If the bufferevent does not already have a socket set, we allocate a new
199 socket here and make it nonblocking before we begin.
200
201 If no address is provided, we assume that the socket is already connecting,
202 and configure the bufferevent so that a BEV_EVENT_CONNECTED event will be
203 yielded when it is done connecting.
204
205 @param bufev an existing bufferevent allocated with
206 bufferevent_socket_new().
207 @param addr the address we should connect to
208 @param socklen The length of the address
209 @return 0 on success, -1 on failure.
210 */
211EVENT2_EXPORT_SYMBOL
212int bufferevent_socket_connect(struct bufferevent *, const struct sockaddr *, int);
213
214struct evdns_base;
215/**
216 Resolve the hostname 'hostname' and connect to it as with
217 bufferevent_socket_connect().
218
219 @param bufev An existing bufferevent allocated with bufferevent_socket_new()
220 @param evdns_base Optionally, an evdns_base to use for resolving hostnames
221 asynchronously. May be set to NULL for a blocking resolve.
222 @param family A preferred address family to resolve addresses to, or
223 AF_UNSPEC for no preference. Only AF_INET, AF_INET6, and AF_UNSPEC are
224 supported.
225 @param hostname The hostname to resolve; see below for notes on recognized
226 formats
227 @param port The port to connect to on the resolved address.
228 @return 0 if successful, -1 on failure.
229
230 Recognized hostname formats are:
231
232 www.example.com (hostname)
233 1.2.3.4 (ipv4address)
234 ::1 (ipv6address)
235 [::1] ([ipv6address])
236
237 Performance note: If you do not provide an evdns_base, this function
238 may block while it waits for a DNS response. This is probably not
239 what you want.
240 */
241EVENT2_EXPORT_SYMBOL
242int bufferevent_socket_connect_hostname(struct bufferevent *,
243 struct evdns_base *, int, const char *, int);
244
245/**
246 Return the error code for the last failed DNS lookup attempt made by
247 bufferevent_socket_connect_hostname().
248
249 @param bev The bufferevent object.
250 @return DNS error code.
251 @see evutil_gai_strerror()
252*/
253EVENT2_EXPORT_SYMBOL
254int bufferevent_socket_get_dns_error(struct bufferevent *bev);
255
256/**
257 Assign a bufferevent to a specific event_base.
258
259 NOTE that only socket bufferevents support this function.
260
261 @param base an event_base returned by event_init()
262 @param bufev a bufferevent struct returned by bufferevent_new()
263 or bufferevent_socket_new()
264 @return 0 if successful, or -1 if an error occurred
265 @see bufferevent_new()
266 */
267EVENT2_EXPORT_SYMBOL
268int bufferevent_base_set(struct event_base *base, struct bufferevent *bufev);
269
270/**
271 Return the event_base used by a bufferevent
272*/
273EVENT2_EXPORT_SYMBOL
274struct event_base *bufferevent_get_base(struct bufferevent *bev);
275
276/**
277 Assign a priority to a bufferevent.
278
279 Only supported for socket bufferevents.
280
281 @param bufev a bufferevent struct
282 @param pri the priority to be assigned
283 @return 0 if successful, or -1 if an error occurred
284 */
285EVENT2_EXPORT_SYMBOL
286int bufferevent_priority_set(struct bufferevent *bufev, int pri);
287
288/**
289 Return the priority of a bufferevent.
290
291 Only supported for socket bufferevents
292 */
293EVENT2_EXPORT_SYMBOL
294int bufferevent_get_priority(const struct bufferevent *bufev);
295
296/**
297 Deallocate the storage associated with a bufferevent structure.
298
299 If there is pending data to write on the bufferevent, it probably won't be
300 flushed before the bufferevent is freed.
301
302 @param bufev the bufferevent structure to be freed.
303 */
304EVENT2_EXPORT_SYMBOL
305void bufferevent_free(struct bufferevent *bufev);
306
307
308/**
309 Changes the callbacks for a bufferevent.
310
311 @param bufev the bufferevent object for which to change callbacks
312 @param readcb callback to invoke when there is data to be read, or NULL if
313 no callback is desired
314 @param writecb callback to invoke when the file descriptor is ready for
315 writing, or NULL if no callback is desired
316 @param eventcb callback to invoke when there is an event on the file
317 descriptor
318 @param cbarg an argument that will be supplied to each of the callbacks
319 (readcb, writecb, and errorcb)
320 @see bufferevent_new()
321 */
322EVENT2_EXPORT_SYMBOL
323void bufferevent_setcb(struct bufferevent *bufev,
324 bufferevent_data_cb readcb, bufferevent_data_cb writecb,
325 bufferevent_event_cb eventcb, void *cbarg);
326
327/**
328 Retrieves the callbacks for a bufferevent.
329
330 @param bufev the bufferevent to examine.
331 @param readcb_ptr if readcb_ptr is nonnull, *readcb_ptr is set to the current
332 read callback for the bufferevent.
333 @param writecb_ptr if writecb_ptr is nonnull, *writecb_ptr is set to the
334 current write callback for the bufferevent.
335 @param eventcb_ptr if eventcb_ptr is nonnull, *eventcb_ptr is set to the
336 current event callback for the bufferevent.
337 @param cbarg_ptr if cbarg_ptr is nonnull, *cbarg_ptr is set to the current
338 callback argument for the bufferevent.
339 @see buffervent_setcb()
340*/
341EVENT2_EXPORT_SYMBOL
342void bufferevent_getcb(struct bufferevent *bufev,
343 bufferevent_data_cb *readcb_ptr,
344 bufferevent_data_cb *writecb_ptr,
345 bufferevent_event_cb *eventcb_ptr,
346 void **cbarg_ptr);
347
348/**
349 Changes the file descriptor on which the bufferevent operates.
350 Not supported for all bufferevent types.
351
352 @param bufev the bufferevent object for which to change the file descriptor
353 @param fd the file descriptor to operate on
354*/
355EVENT2_EXPORT_SYMBOL
356int bufferevent_setfd(struct bufferevent *bufev, evutil_socket_t fd);
357
358/**
359 Returns the file descriptor associated with a bufferevent, or -1 if
360 no file descriptor is associated with the bufferevent.
361 */
362EVENT2_EXPORT_SYMBOL
363evutil_socket_t bufferevent_getfd(struct bufferevent *bufev);
364
365/**
366 Returns the underlying bufferevent associated with a bufferevent (if
367 the bufferevent is a wrapper), or NULL if there is no underlying bufferevent.
368 */
369EVENT2_EXPORT_SYMBOL
370struct bufferevent *bufferevent_get_underlying(struct bufferevent *bufev);
371
372/**
373 Write data to a bufferevent buffer.
374
375 The bufferevent_write() function can be used to write data to the file
376 descriptor. The data is appended to the output buffer and written to the
377 descriptor automatically as it becomes available for writing.
378
379 @param bufev the bufferevent to be written to
380 @param data a pointer to the data to be written
381 @param size the length of the data, in bytes
382 @return 0 if successful, or -1 if an error occurred
383 @see bufferevent_write_buffer()
384 */
385EVENT2_EXPORT_SYMBOL
386int bufferevent_write(struct bufferevent *bufev,
387 const void *data, size_t size);
388
389
390/**
391 Write data from an evbuffer to a bufferevent buffer. The evbuffer is
392 being drained as a result.
393
394 @param bufev the bufferevent to be written to
395 @param buf the evbuffer to be written
396 @return 0 if successful, or -1 if an error occurred
397 @see bufferevent_write()
398 */
399EVENT2_EXPORT_SYMBOL
400int bufferevent_write_buffer(struct bufferevent *bufev, struct evbuffer *buf);
401
402
403/**
404 Read data from a bufferevent buffer.
405
406 The bufferevent_read() function is used to read data from the input buffer.
407
408 @param bufev the bufferevent to be read from
409 @param data pointer to a buffer that will store the data
410 @param size the size of the data buffer, in bytes
411 @return the amount of data read, in bytes.
412 */
413EVENT2_EXPORT_SYMBOL
414size_t bufferevent_read(struct bufferevent *bufev, void *data, size_t size);
415
416/**
417 Read data from a bufferevent buffer into an evbuffer. This avoids
418 memory copies.
419
420 @param bufev the bufferevent to be read from
421 @param buf the evbuffer to which to add data
422 @return 0 if successful, or -1 if an error occurred.
423 */
424EVENT2_EXPORT_SYMBOL
425int bufferevent_read_buffer(struct bufferevent *bufev, struct evbuffer *buf);
426
427/**
428 Returns the input buffer.
429
430 The user MUST NOT set the callback on this buffer.
431
432 @param bufev the bufferevent from which to get the evbuffer
433 @return the evbuffer object for the input buffer
434 */
435
436EVENT2_EXPORT_SYMBOL
437struct evbuffer *bufferevent_get_input(struct bufferevent *bufev);
438
439/**
440 Returns the output buffer.
441
442 The user MUST NOT set the callback on this buffer.
443
444 When filters are being used, the filters need to be manually
445 triggered if the output buffer was manipulated.
446
447 @param bufev the bufferevent from which to get the evbuffer
448 @return the evbuffer object for the output buffer
449 */
450
451EVENT2_EXPORT_SYMBOL
452struct evbuffer *bufferevent_get_output(struct bufferevent *bufev);
453
454/**
455 Enable a bufferevent.
456
457 @param bufev the bufferevent to be enabled
458 @param event any combination of EV_READ | EV_WRITE.
459 @return 0 if successful, or -1 if an error occurred
460 @see bufferevent_disable()
461 */
462EVENT2_EXPORT_SYMBOL
463int bufferevent_enable(struct bufferevent *bufev, short event);
464
465/**
466 Disable a bufferevent.
467
468 @param bufev the bufferevent to be disabled
469 @param event any combination of EV_READ | EV_WRITE.
470 @return 0 if successful, or -1 if an error occurred
471 @see bufferevent_enable()
472 */
473EVENT2_EXPORT_SYMBOL
474int bufferevent_disable(struct bufferevent *bufev, short event);
475
476/**
477 Return the events that are enabled on a given bufferevent.
478
479 @param bufev the bufferevent to inspect
480 @return A combination of EV_READ | EV_WRITE
481 */
482EVENT2_EXPORT_SYMBOL
483short bufferevent_get_enabled(struct bufferevent *bufev);
484
485/**
486 Set the read and write timeout for a bufferevent.
487
488 A bufferevent's timeout will fire the first time that the indicated
489 amount of time has elapsed since a successful read or write operation,
490 during which the bufferevent was trying to read or write.
491
492 (In other words, if reading or writing is disabled, or if the
493 bufferevent's read or write operation has been suspended because
494 there's no data to write, or not enough bandwidth, or so on, the
495 timeout isn't active. The timeout only becomes active when we we're
496 willing to actually read or write.)
497
498 Calling bufferevent_enable or setting a timeout for a bufferevent
499 whose timeout is already pending resets its timeout.
500
501 If the timeout elapses, the corresponding operation (EV_READ or
502 EV_WRITE) becomes disabled until you re-enable it again. The
503 bufferevent's event callback is called with the
504 BEV_EVENT_TIMEOUT|BEV_EVENT_READING or
505 BEV_EVENT_TIMEOUT|BEV_EVENT_WRITING.
506
507 @param bufev the bufferevent to be modified
508 @param timeout_read the read timeout, or NULL
509 @param timeout_write the write timeout, or NULL
510 */
511EVENT2_EXPORT_SYMBOL
512int bufferevent_set_timeouts(struct bufferevent *bufev,
513 const struct timeval *timeout_read, const struct timeval *timeout_write);
514
515/**
516 Sets the watermarks for read and write events.
517
518 On input, a bufferevent does not invoke the user read callback unless
519 there is at least low watermark data in the buffer. If the read buffer
520 is beyond the high watermark, the bufferevent stops reading from the network.
521 But be aware that bufferevent input/read buffer can overrun high watermark
522 limit (typical example is openssl bufferevent), so you should not relay in
523 this.
524
525 On output, the user write callback is invoked whenever the buffered data
526 falls below the low watermark. Filters that write to this bufev will try
527 not to write more bytes to this buffer than the high watermark would allow,
528 except when flushing.
529
530 @param bufev the bufferevent to be modified
531 @param events EV_READ, EV_WRITE or both
532 @param lowmark the lower watermark to set
533 @param highmark the high watermark to set
534*/
535
536EVENT2_EXPORT_SYMBOL
537void bufferevent_setwatermark(struct bufferevent *bufev, short events,
538 size_t lowmark, size_t highmark);
539
540/**
541 Retrieves the watermarks for read or write events.
542 Returns non-zero if events contains not only EV_READ or EV_WRITE.
543 Returns zero if events equal EV_READ or EV_WRITE
544
545 @param bufev the bufferevent to be examined
546 @param events EV_READ or EV_WRITE
547 @param lowmark receives the lower watermark if not NULL
548 @param highmark receives the high watermark if not NULL
549*/
550EVENT2_EXPORT_SYMBOL
551int bufferevent_getwatermark(struct bufferevent *bufev, short events,
552 size_t *lowmark, size_t *highmark);
553
554/**
555 Acquire the lock on a bufferevent. Has no effect if locking was not
556 enabled with BEV_OPT_THREADSAFE.
557 */
558EVENT2_EXPORT_SYMBOL
559void bufferevent_lock(struct bufferevent *bufev);
560
561/**
562 Release the lock on a bufferevent. Has no effect if locking was not
563 enabled with BEV_OPT_THREADSAFE.
564 */
565EVENT2_EXPORT_SYMBOL
566void bufferevent_unlock(struct bufferevent *bufev);
567
568
569/**
570 * Public interface to manually increase the reference count of a bufferevent
571 * this is useful in situations where a user may reference the bufferevent
572 * somewhere else (unknown to libevent)
573 *
574 * @param bufev the bufferevent to increase the refcount on
575 *
576 */
577EVENT2_EXPORT_SYMBOL
578void bufferevent_incref(struct bufferevent *bufev);
579
580/**
581 * Public interface to manually decrement the reference count of a bufferevent
582 *
583 * Warning: make sure you know what you're doing. This is mainly used in
584 * conjunction with bufferevent_incref(). This will free up all data associated
585 * with a bufferevent if the reference count hits 0.
586 *
587 * @param bufev the bufferevent to decrement the refcount on
588 *
589 * @return 1 if the bufferevent was freed, otherwise 0 (still referenced)
590 */
591EVENT2_EXPORT_SYMBOL
592int bufferevent_decref(struct bufferevent *bufev);
593
594/**
595 Flags that can be passed into filters to let them know how to
596 deal with the incoming data.
597*/
598enum bufferevent_flush_mode {
599 /** usually set when processing data */
600 BEV_NORMAL = 0,
601
602 /** want to checkpoint all data sent. */
603 BEV_FLUSH = 1,
604
605 /** encountered EOF on read or done sending data */
606 BEV_FINISHED = 2
607};
608
609/**
610 Triggers the bufferevent to produce more data if possible.
611
612 @param bufev the bufferevent object
613 @param iotype either EV_READ or EV_WRITE or both.
614 @param mode either BEV_NORMAL or BEV_FLUSH or BEV_FINISHED
615 @return -1 on failure, 0 if no data was produces, 1 if data was produced
616 */
617EVENT2_EXPORT_SYMBOL
618int bufferevent_flush(struct bufferevent *bufev,
619 short iotype,
620 enum bufferevent_flush_mode mode);
621
622/**
623 Flags for bufferevent_trigger(_event) that modify when and how to trigger
624 the callback.
625*/
626enum bufferevent_trigger_options {
627 /** trigger the callback regardless of the watermarks */
628 BEV_TRIG_IGNORE_WATERMARKS = (1<<16),
629
630 /** defer even if the callbacks are not */
631 BEV_TRIG_DEFER_CALLBACKS = BEV_OPT_DEFER_CALLBACKS
632
633 /* (Note: for internal reasons, these need to be disjoint from
634 * bufferevent_options, except when they mean the same thing. */
635};
636
637/**
638 Triggers bufferevent data callbacks.
639
640 The function will honor watermarks unless options contain
641 BEV_TRIG_IGNORE_WATERMARKS. If the options contain BEV_OPT_DEFER_CALLBACKS,
642 the callbacks are deferred.
643
644 @param bufev the bufferevent object
645 @param iotype either EV_READ or EV_WRITE or both.
646 @param options
647 */
648EVENT2_EXPORT_SYMBOL
649void bufferevent_trigger(struct bufferevent *bufev, short iotype,
650 int options);
651
652/**
653 Triggers the bufferevent event callback.
654
655 If the options contain BEV_OPT_DEFER_CALLBACKS, the callbacks are deferred.
656
657 @param bufev the bufferevent object
658 @param what the flags to pass onto the event callback
659 @param options
660 */
661EVENT2_EXPORT_SYMBOL
662void bufferevent_trigger_event(struct bufferevent *bufev, short what,
663 int options);
664
665/**
666 @name Filtering support
667
668 @{
669*/
670/**
671 Values that filters can return.
672 */
673enum bufferevent_filter_result {
674 /** everything is okay */
675 BEV_OK = 0,
676
677 /** the filter needs to read more data before output */
678 BEV_NEED_MORE = 1,
679
680 /** the filter encountered a critical error, no further data
681 can be processed. */
682 BEV_ERROR = 2
683};
684
685/** A callback function to implement a filter for a bufferevent.
686
687 @param src An evbuffer to drain data from.
688 @param dst An evbuffer to add data to.
689 @param limit A suggested upper bound of bytes to write to dst.
690 The filter may ignore this value, but doing so means that
691 it will overflow the high-water mark associated with dst.
692 -1 means "no limit".
693 @param mode Whether we should write data as may be convenient
694 (BEV_NORMAL), or flush as much data as we can (BEV_FLUSH),
695 or flush as much as we can, possibly including an end-of-stream
696 marker (BEV_FINISH).
697 @param ctx A user-supplied pointer.
698
699 @return BEV_OK if we wrote some data; BEV_NEED_MORE if we can't
700 produce any more output until we get some input; and BEV_ERROR
701 on an error.
702 */
703typedef enum bufferevent_filter_result (*bufferevent_filter_cb)(
704 struct evbuffer *src, struct evbuffer *dst, ev_ssize_t dst_limit,
705 enum bufferevent_flush_mode mode, void *ctx);
706
707/**
708 Allocate a new filtering bufferevent on top of an existing bufferevent.
709
710 @param underlying the underlying bufferevent.
711 @param input_filter The filter to apply to data we read from the underlying
712 bufferevent
713 @param output_filter The filer to apply to data we write to the underlying
714 bufferevent
715 @param options A bitfield of bufferevent options.
716 @param free_context A function to use to free the filter context when
717 this bufferevent is freed.
718 @param ctx A context pointer to pass to the filter functions.
719 */
720EVENT2_EXPORT_SYMBOL
721struct bufferevent *
722bufferevent_filter_new(struct bufferevent *underlying,
723 bufferevent_filter_cb input_filter,
724 bufferevent_filter_cb output_filter,
725 int options,
726 void (*free_context)(void *),
727 void *ctx);
728/**@}*/
729
730/**
731 Allocate a pair of linked bufferevents. The bufferevents behave as would
732 two bufferevent_sock instances connected to opposite ends of a
733 socketpair(), except that no internal socketpair is allocated.
734
735 @param base The event base to associate with the socketpair.
736 @param options A set of options for this bufferevent
737 @param pair A pointer to an array to hold the two new bufferevent objects.
738 @return 0 on success, -1 on failure.
739 */
740EVENT2_EXPORT_SYMBOL
741int bufferevent_pair_new(struct event_base *base, int options,
742 struct bufferevent *pair[2]);
743
744/**
745 Given one bufferevent returned by bufferevent_pair_new(), returns the
746 other one if it still exists. Otherwise returns NULL.
747 */
748EVENT2_EXPORT_SYMBOL
749struct bufferevent *bufferevent_pair_get_partner(struct bufferevent *bev);
750
751/**
752 Abstract type used to configure rate-limiting on a bufferevent or a group
753 of bufferevents.
754 */
755struct ev_token_bucket_cfg;
756
757/**
758 A group of bufferevents which are configured to respect the same rate
759 limit.
760*/
761struct bufferevent_rate_limit_group;
762
763/** Maximum configurable rate- or burst-limit. */
764#define EV_RATE_LIMIT_MAX EV_SSIZE_MAX
765
766/**
767 Initialize and return a new object to configure the rate-limiting behavior
768 of bufferevents.
769
770 @param read_rate The maximum number of bytes to read per tick on
771 average.
772 @param read_burst The maximum number of bytes to read in any single tick.
773 @param write_rate The maximum number of bytes to write per tick on
774 average.
775 @param write_burst The maximum number of bytes to write in any single tick.
776 @param tick_len The length of a single tick. Defaults to one second.
777 Any fractions of a millisecond are ignored.
778
779 Note that all rate-limits hare are currently best-effort: future versions
780 of Libevent may implement them more tightly.
781 */
782EVENT2_EXPORT_SYMBOL
783struct ev_token_bucket_cfg *ev_token_bucket_cfg_new(
784 size_t read_rate, size_t read_burst,
785 size_t write_rate, size_t write_burst,
786 const struct timeval *tick_len);
787
788/** Free all storage held in 'cfg'.
789
790 Note: 'cfg' is not currently reference-counted; it is not safe to free it
791 until no bufferevent is using it.
792 */
793EVENT2_EXPORT_SYMBOL
794void ev_token_bucket_cfg_free(struct ev_token_bucket_cfg *cfg);
795
796/**
797 Set the rate-limit of a the bufferevent 'bev' to the one specified in
798 'cfg'. If 'cfg' is NULL, disable any per-bufferevent rate-limiting on
799 'bev'.
800
801 Note that only some bufferevent types currently respect rate-limiting.
802 They are: socket-based bufferevents (normal and IOCP-based), and SSL-based
803 bufferevents.
804
805 Return 0 on success, -1 on failure.
806 */
807EVENT2_EXPORT_SYMBOL
808int bufferevent_set_rate_limit(struct bufferevent *bev,
809 struct ev_token_bucket_cfg *cfg);
810
811/**
812 Create a new rate-limit group for bufferevents. A rate-limit group
813 constrains the maximum number of bytes sent and received, in toto,
814 by all of its bufferevents.
815
816 @param base An event_base to run any necessary timeouts for the group.
817 Note that all bufferevents in the group do not necessarily need to share
818 this event_base.
819 @param cfg The rate-limit for this group.
820
821 Note that all rate-limits hare are currently best-effort: future versions
822 of Libevent may implement them more tightly.
823
824 Note also that only some bufferevent types currently respect rate-limiting.
825 They are: socket-based bufferevents (normal and IOCP-based), and SSL-based
826 bufferevents.
827 */
828EVENT2_EXPORT_SYMBOL
829struct bufferevent_rate_limit_group *bufferevent_rate_limit_group_new(
830 struct event_base *base,
831 const struct ev_token_bucket_cfg *cfg);
832/**
833 Change the rate-limiting settings for a given rate-limiting group.
834
835 Return 0 on success, -1 on failure.
836*/
837EVENT2_EXPORT_SYMBOL
838int bufferevent_rate_limit_group_set_cfg(
839 struct bufferevent_rate_limit_group *,
840 const struct ev_token_bucket_cfg *);
841
842/**
843 Change the smallest quantum we're willing to allocate to any single
844 bufferevent in a group for reading or writing at a time.
845
846 The rationale is that, because of TCP/IP protocol overheads and kernel
847 behavior, if a rate-limiting group is so tight on bandwidth that you're
848 only willing to send 1 byte per tick per bufferevent, you might instead
849 want to batch up the reads and writes so that you send N bytes per
850 1/N of the bufferevents (chosen at random) each tick, so you still wind
851 up send 1 byte per tick per bufferevent on average, but you don't send
852 so many tiny packets.
853
854 The default min-share is currently 64 bytes.
855
856 Returns 0 on success, -1 on failure.
857 */
858EVENT2_EXPORT_SYMBOL
859int bufferevent_rate_limit_group_set_min_share(
860 struct bufferevent_rate_limit_group *, size_t);
861
862/**
863 Free a rate-limiting group. The group must have no members when
864 this function is called.
865*/
866EVENT2_EXPORT_SYMBOL
867void bufferevent_rate_limit_group_free(struct bufferevent_rate_limit_group *);
868
869/**
870 Add 'bev' to the list of bufferevents whose aggregate reading and writing
871 is restricted by 'g'. If 'g' is NULL, remove 'bev' from its current group.
872
873 A bufferevent may belong to no more than one rate-limit group at a time.
874 If 'bev' is already a member of a group, it will be removed from its old
875 group before being added to 'g'.
876
877 Return 0 on success and -1 on failure.
878 */
879EVENT2_EXPORT_SYMBOL
880int bufferevent_add_to_rate_limit_group(struct bufferevent *bev,
881 struct bufferevent_rate_limit_group *g);
882
883/** Remove 'bev' from its current rate-limit group (if any). */
884EVENT2_EXPORT_SYMBOL
885int bufferevent_remove_from_rate_limit_group(struct bufferevent *bev);
886
887/**
888 Set the size limit for single read operation.
889
890 Set to 0 for a reasonable default.
891
892 Return 0 on success and -1 on failure.
893 */
894EVENT2_EXPORT_SYMBOL
895int bufferevent_set_max_single_read(struct bufferevent *bev, size_t size);
896
897/**
898 Set the size limit for single write operation.
899
900 Set to 0 for a reasonable default.
901
902 Return 0 on success and -1 on failure.
903 */
904EVENT2_EXPORT_SYMBOL
905int bufferevent_set_max_single_write(struct bufferevent *bev, size_t size);
906
907/** Get the current size limit for single read operation. */
908EVENT2_EXPORT_SYMBOL
909ev_ssize_t bufferevent_get_max_single_read(struct bufferevent *bev);
910
911/** Get the current size limit for single write operation. */
912EVENT2_EXPORT_SYMBOL
913ev_ssize_t bufferevent_get_max_single_write(struct bufferevent *bev);
914
915/**
916 @name Rate limit inspection
917
918 Return the current read or write bucket size for a bufferevent.
919 If it is not configured with a per-bufferevent ratelimit, return
920 EV_SSIZE_MAX. This function does not inspect the group limit, if any.
921 Note that it can return a negative value if the bufferevent has been
922 made to read or write more than its limit.
923
924 @{
925 */
926EVENT2_EXPORT_SYMBOL
927ev_ssize_t bufferevent_get_read_limit(struct bufferevent *bev);
928EVENT2_EXPORT_SYMBOL
929ev_ssize_t bufferevent_get_write_limit(struct bufferevent *bev);
930/*@}*/
931
932EVENT2_EXPORT_SYMBOL
933ev_ssize_t bufferevent_get_max_to_read(struct bufferevent *bev);
934EVENT2_EXPORT_SYMBOL
935ev_ssize_t bufferevent_get_max_to_write(struct bufferevent *bev);
936
937EVENT2_EXPORT_SYMBOL
938const struct ev_token_bucket_cfg *bufferevent_get_token_bucket_cfg(const struct bufferevent * bev);
939
940/**
941 @name Group Rate limit inspection
942
943 Return the read or write bucket size for a bufferevent rate limit
944 group. Note that it can return a negative value if bufferevents in
945 the group have been made to read or write more than their limits.
946
947 @{
948 */
949EVENT2_EXPORT_SYMBOL
950ev_ssize_t bufferevent_rate_limit_group_get_read_limit(
951 struct bufferevent_rate_limit_group *);
952EVENT2_EXPORT_SYMBOL
953ev_ssize_t bufferevent_rate_limit_group_get_write_limit(
954 struct bufferevent_rate_limit_group *);
955/*@}*/
956
957/**
958 @name Rate limit manipulation
959
960 Subtract a number of bytes from a bufferevent's read or write bucket.
961 The decrement value can be negative, if you want to manually refill
962 the bucket. If the change puts the bucket above or below zero, the
963 bufferevent will resume or suspend reading writing as appropriate.
964 These functions make no change in the buckets for the bufferevent's
965 group, if any.
966
967 Returns 0 on success, -1 on internal error.
968
969 @{
970 */
971EVENT2_EXPORT_SYMBOL
972int bufferevent_decrement_read_limit(struct bufferevent *bev, ev_ssize_t decr);
973EVENT2_EXPORT_SYMBOL
974int bufferevent_decrement_write_limit(struct bufferevent *bev, ev_ssize_t decr);
975/*@}*/
976
977/**
978 @name Group rate limit manipulation
979
980 Subtract a number of bytes from a bufferevent rate-limiting group's
981 read or write bucket. The decrement value can be negative, if you
982 want to manually refill the bucket. If the change puts the bucket
983 above or below zero, the bufferevents in the group will resume or
984 suspend reading writing as appropriate.
985
986 Returns 0 on success, -1 on internal error.
987
988 @{
989 */
990EVENT2_EXPORT_SYMBOL
991int bufferevent_rate_limit_group_decrement_read(
992 struct bufferevent_rate_limit_group *, ev_ssize_t);
993EVENT2_EXPORT_SYMBOL
994int bufferevent_rate_limit_group_decrement_write(
995 struct bufferevent_rate_limit_group *, ev_ssize_t);
996/*@}*/
997
998
999/**
1000 * Inspect the total bytes read/written on a group.
1001 *
1002 * Set the variable pointed to by total_read_out to the total number of bytes
1003 * ever read on grp, and the variable pointed to by total_written_out to the
1004 * total number of bytes ever written on grp. */
1005EVENT2_EXPORT_SYMBOL
1006void bufferevent_rate_limit_group_get_totals(
1007 struct bufferevent_rate_limit_group *grp,
1008 ev_uint64_t *total_read_out, ev_uint64_t *total_written_out);
1009
1010/**
1011 * Reset the total bytes read/written on a group.
1012 *
1013 * Reset the number of bytes read or written on grp as given by
1014 * bufferevent_rate_limit_group_reset_totals(). */
1015EVENT2_EXPORT_SYMBOL
1016void
1017bufferevent_rate_limit_group_reset_totals(
1018 struct bufferevent_rate_limit_group *grp);
1019
1020#ifdef __cplusplus
1021}
1022#endif
1023
1024#endif /* EVENT2_BUFFEREVENT_H_INCLUDED_ */
1025

source code of include/event2/bufferevent.h