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 banwidth, 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
522 On output, the user write callback is invoked whenever the buffered data
523 falls below the low watermark. Filters that write to this bufev will try
524 not to write more bytes to this buffer than the high watermark would allow,
525 except when flushing.
526
527 @param bufev the bufferevent to be modified
528 @param events EV_READ, EV_WRITE or both
529 @param lowmark the lower watermark to set
530 @param highmark the high watermark to set
531*/
532
533EVENT2_EXPORT_SYMBOL
534void bufferevent_setwatermark(struct bufferevent *bufev, short events,
535 size_t lowmark, size_t highmark);
536
537/**
538 Retrieves the watermarks for read or write events.
539 Returns non-zero if events contains not only EV_READ or EV_WRITE.
540 Returns zero if events equal EV_READ or EV_WRITE
541
542 @param bufev the bufferevent to be examined
543 @param events EV_READ or EV_WRITE
544 @param lowmark receives the lower watermark if not NULL
545 @param highmark receives the high watermark if not NULL
546*/
547EVENT2_EXPORT_SYMBOL
548int bufferevent_getwatermark(struct bufferevent *bufev, short events,
549 size_t *lowmark, size_t *highmark);
550
551/**
552 Acquire the lock on a bufferevent. Has no effect if locking was not
553 enabled with BEV_OPT_THREADSAFE.
554 */
555EVENT2_EXPORT_SYMBOL
556void bufferevent_lock(struct bufferevent *bufev);
557
558/**
559 Release the lock on a bufferevent. Has no effect if locking was not
560 enabled with BEV_OPT_THREADSAFE.
561 */
562EVENT2_EXPORT_SYMBOL
563void bufferevent_unlock(struct bufferevent *bufev);
564
565
566/**
567 * Public interface to manually increase the reference count of a bufferevent
568 * this is useful in situations where a user may reference the bufferevent
569 * somewhere eles (unknown to libevent)
570 *
571 * @param bufev the bufferevent to increase the refcount on
572 *
573 */
574EVENT2_EXPORT_SYMBOL
575void bufferevent_incref(struct bufferevent *bufev);
576
577/**
578 * Public interface to manually decrement the reference count of a bufferevent
579 *
580 * Warning: make sure you know what you're doing. This is mainly used in
581 * conjunction with bufferevent_incref(). This will free up all data associated
582 * with a bufferevent if the reference count hits 0.
583 *
584 * @param bufev the bufferevent to decrement the refcount on
585 *
586 * @return 1 if the bufferevent was freed, otherwise 0 (still referenced)
587 */
588EVENT2_EXPORT_SYMBOL
589int bufferevent_decref(struct bufferevent *bufev);
590
591/**
592 Flags that can be passed into filters to let them know how to
593 deal with the incoming data.
594*/
595enum bufferevent_flush_mode {
596 /** usually set when processing data */
597 BEV_NORMAL = 0,
598
599 /** want to checkpoint all data sent. */
600 BEV_FLUSH = 1,
601
602 /** encountered EOF on read or done sending data */
603 BEV_FINISHED = 2
604};
605
606/**
607 Triggers the bufferevent to produce more data if possible.
608
609 @param bufev the bufferevent object
610 @param iotype either EV_READ or EV_WRITE or both.
611 @param mode either BEV_NORMAL or BEV_FLUSH or BEV_FINISHED
612 @return -1 on failure, 0 if no data was produces, 1 if data was produced
613 */
614EVENT2_EXPORT_SYMBOL
615int bufferevent_flush(struct bufferevent *bufev,
616 short iotype,
617 enum bufferevent_flush_mode mode);
618
619/**
620 Flags for bufferevent_trigger(_event) that modify when and how to trigger
621 the callback.
622*/
623enum bufferevent_trigger_options {
624 /** trigger the callback regardless of the watermarks */
625 BEV_TRIG_IGNORE_WATERMARKS = (1<<16),
626
627 /** defer even if the callbacks are not */
628 BEV_TRIG_DEFER_CALLBACKS = BEV_OPT_DEFER_CALLBACKS
629
630 /* (Note: for internal reasons, these need to be disjoint from
631 * bufferevent_options, except when they mean the same thing. */
632};
633
634/**
635 Triggers bufferevent data callbacks.
636
637 The function will honor watermarks unless options contain
638 BEV_TRIG_IGNORE_WATERMARKS. If the options contain BEV_OPT_DEFER_CALLBACKS,
639 the callbacks are deferred.
640
641 @param bufev the bufferevent object
642 @param iotype either EV_READ or EV_WRITE or both.
643 @param options
644 */
645EVENT2_EXPORT_SYMBOL
646void bufferevent_trigger(struct bufferevent *bufev, short iotype,
647 int options);
648
649/**
650 Triggers the bufferevent event callback.
651
652 If the options contain BEV_OPT_DEFER_CALLBACKS, the callbacks are deferred.
653
654 @param bufev the bufferevent object
655 @param what the flags to pass onto the event callback
656 @param options
657 */
658EVENT2_EXPORT_SYMBOL
659void bufferevent_trigger_event(struct bufferevent *bufev, short what,
660 int options);
661
662/**
663 @name Filtering support
664
665 @{
666*/
667/**
668 Values that filters can return.
669 */
670enum bufferevent_filter_result {
671 /** everything is okay */
672 BEV_OK = 0,
673
674 /** the filter needs to read more data before output */
675 BEV_NEED_MORE = 1,
676
677 /** the filter encountered a critical error, no further data
678 can be processed. */
679 BEV_ERROR = 2
680};
681
682/** A callback function to implement a filter for a bufferevent.
683
684 @param src An evbuffer to drain data from.
685 @param dst An evbuffer to add data to.
686 @param limit A suggested upper bound of bytes to write to dst.
687 The filter may ignore this value, but doing so means that
688 it will overflow the high-water mark associated with dst.
689 -1 means "no limit".
690 @param mode Whether we should write data as may be convenient
691 (BEV_NORMAL), or flush as much data as we can (BEV_FLUSH),
692 or flush as much as we can, possibly including an end-of-stream
693 marker (BEV_FINISH).
694 @param ctx A user-supplied pointer.
695
696 @return BEV_OK if we wrote some data; BEV_NEED_MORE if we can't
697 produce any more output until we get some input; and BEV_ERROR
698 on an error.
699 */
700typedef enum bufferevent_filter_result (*bufferevent_filter_cb)(
701 struct evbuffer *src, struct evbuffer *dst, ev_ssize_t dst_limit,
702 enum bufferevent_flush_mode mode, void *ctx);
703
704/**
705 Allocate a new filtering bufferevent on top of an existing bufferevent.
706
707 @param underlying the underlying bufferevent.
708 @param input_filter The filter to apply to data we read from the underlying
709 bufferevent
710 @param output_filter The filer to apply to data we write to the underlying
711 bufferevent
712 @param options A bitfield of bufferevent options.
713 @param free_context A function to use to free the filter context when
714 this bufferevent is freed.
715 @param ctx A context pointer to pass to the filter functions.
716 */
717EVENT2_EXPORT_SYMBOL
718struct bufferevent *
719bufferevent_filter_new(struct bufferevent *underlying,
720 bufferevent_filter_cb input_filter,
721 bufferevent_filter_cb output_filter,
722 int options,
723 void (*free_context)(void *),
724 void *ctx);
725/**@}*/
726
727/**
728 Allocate a pair of linked bufferevents. The bufferevents behave as would
729 two bufferevent_sock instances connected to opposite ends of a
730 socketpair(), except that no internal socketpair is allocated.
731
732 @param base The event base to associate with the socketpair.
733 @param options A set of options for this bufferevent
734 @param pair A pointer to an array to hold the two new bufferevent objects.
735 @return 0 on success, -1 on failure.
736 */
737EVENT2_EXPORT_SYMBOL
738int bufferevent_pair_new(struct event_base *base, int options,
739 struct bufferevent *pair[2]);
740
741/**
742 Given one bufferevent returned by bufferevent_pair_new(), returns the
743 other one if it still exists. Otherwise returns NULL.
744 */
745EVENT2_EXPORT_SYMBOL
746struct bufferevent *bufferevent_pair_get_partner(struct bufferevent *bev);
747
748/**
749 Abstract type used to configure rate-limiting on a bufferevent or a group
750 of bufferevents.
751 */
752struct ev_token_bucket_cfg;
753
754/**
755 A group of bufferevents which are configured to respect the same rate
756 limit.
757*/
758struct bufferevent_rate_limit_group;
759
760/** Maximum configurable rate- or burst-limit. */
761#define EV_RATE_LIMIT_MAX EV_SSIZE_MAX
762
763/**
764 Initialize and return a new object to configure the rate-limiting behavior
765 of bufferevents.
766
767 @param read_rate The maximum number of bytes to read per tick on
768 average.
769 @param read_burst The maximum number of bytes to read in any single tick.
770 @param write_rate The maximum number of bytes to write per tick on
771 average.
772 @param write_burst The maximum number of bytes to write in any single tick.
773 @param tick_len The length of a single tick. Defaults to one second.
774 Any fractions of a millisecond are ignored.
775
776 Note that all rate-limits hare are currently best-effort: future versions
777 of Libevent may implement them more tightly.
778 */
779EVENT2_EXPORT_SYMBOL
780struct ev_token_bucket_cfg *ev_token_bucket_cfg_new(
781 size_t read_rate, size_t read_burst,
782 size_t write_rate, size_t write_burst,
783 const struct timeval *tick_len);
784
785/** Free all storage held in 'cfg'.
786
787 Note: 'cfg' is not currently reference-counted; it is not safe to free it
788 until no bufferevent is using it.
789 */
790EVENT2_EXPORT_SYMBOL
791void ev_token_bucket_cfg_free(struct ev_token_bucket_cfg *cfg);
792
793/**
794 Set the rate-limit of a the bufferevent 'bev' to the one specified in
795 'cfg'. If 'cfg' is NULL, disable any per-bufferevent rate-limiting on
796 'bev'.
797
798 Note that only some bufferevent types currently respect rate-limiting.
799 They are: socket-based bufferevents (normal and IOCP-based), and SSL-based
800 bufferevents.
801
802 Return 0 on sucess, -1 on failure.
803 */
804EVENT2_EXPORT_SYMBOL
805int bufferevent_set_rate_limit(struct bufferevent *bev,
806 struct ev_token_bucket_cfg *cfg);
807
808/**
809 Create a new rate-limit group for bufferevents. A rate-limit group
810 constrains the maximum number of bytes sent and received, in toto,
811 by all of its bufferevents.
812
813 @param base An event_base to run any necessary timeouts for the group.
814 Note that all bufferevents in the group do not necessarily need to share
815 this event_base.
816 @param cfg The rate-limit for this group.
817
818 Note that all rate-limits hare are currently best-effort: future versions
819 of Libevent may implement them more tightly.
820
821 Note also that only some bufferevent types currently respect rate-limiting.
822 They are: socket-based bufferevents (normal and IOCP-based), and SSL-based
823 bufferevents.
824 */
825EVENT2_EXPORT_SYMBOL
826struct bufferevent_rate_limit_group *bufferevent_rate_limit_group_new(
827 struct event_base *base,
828 const struct ev_token_bucket_cfg *cfg);
829/**
830 Change the rate-limiting settings for a given rate-limiting group.
831
832 Return 0 on success, -1 on failure.
833*/
834EVENT2_EXPORT_SYMBOL
835int bufferevent_rate_limit_group_set_cfg(
836 struct bufferevent_rate_limit_group *,
837 const struct ev_token_bucket_cfg *);
838
839/**
840 Change the smallest quantum we're willing to allocate to any single
841 bufferevent in a group for reading or writing at a time.
842
843 The rationale is that, because of TCP/IP protocol overheads and kernel
844 behavior, if a rate-limiting group is so tight on bandwidth that you're
845 only willing to send 1 byte per tick per bufferevent, you might instead
846 want to batch up the reads and writes so that you send N bytes per
847 1/N of the bufferevents (chosen at random) each tick, so you still wind
848 up send 1 byte per tick per bufferevent on average, but you don't send
849 so many tiny packets.
850
851 The default min-share is currently 64 bytes.
852
853 Returns 0 on success, -1 on faulre.
854 */
855EVENT2_EXPORT_SYMBOL
856int bufferevent_rate_limit_group_set_min_share(
857 struct bufferevent_rate_limit_group *, size_t);
858
859/**
860 Free a rate-limiting group. The group must have no members when
861 this function is called.
862*/
863EVENT2_EXPORT_SYMBOL
864void bufferevent_rate_limit_group_free(struct bufferevent_rate_limit_group *);
865
866/**
867 Add 'bev' to the list of bufferevents whose aggregate reading and writing
868 is restricted by 'g'. If 'g' is NULL, remove 'bev' from its current group.
869
870 A bufferevent may belong to no more than one rate-limit group at a time.
871 If 'bev' is already a member of a group, it will be removed from its old
872 group before being added to 'g'.
873
874 Return 0 on success and -1 on failure.
875 */
876EVENT2_EXPORT_SYMBOL
877int bufferevent_add_to_rate_limit_group(struct bufferevent *bev,
878 struct bufferevent_rate_limit_group *g);
879
880/** Remove 'bev' from its current rate-limit group (if any). */
881EVENT2_EXPORT_SYMBOL
882int bufferevent_remove_from_rate_limit_group(struct bufferevent *bev);
883
884/**
885 Set the size limit for single read operation.
886
887 Set to 0 for a reasonable default.
888
889 Return 0 on success and -1 on failure.
890 */
891EVENT2_EXPORT_SYMBOL
892int bufferevent_set_max_single_read(struct bufferevent *bev, size_t size);
893
894/**
895 Set the size limit for single write operation.
896
897 Set to 0 for a reasonable default.
898
899 Return 0 on success and -1 on failure.
900 */
901EVENT2_EXPORT_SYMBOL
902int bufferevent_set_max_single_write(struct bufferevent *bev, size_t size);
903
904/** Get the current size limit for single read operation. */
905EVENT2_EXPORT_SYMBOL
906ev_ssize_t bufferevent_get_max_single_read(struct bufferevent *bev);
907
908/** Get the current size limit for single write operation. */
909EVENT2_EXPORT_SYMBOL
910ev_ssize_t bufferevent_get_max_single_write(struct bufferevent *bev);
911
912/**
913 @name Rate limit inspection
914
915 Return the current read or write bucket size for a bufferevent.
916 If it is not configured with a per-bufferevent ratelimit, return
917 EV_SSIZE_MAX. This function does not inspect the group limit, if any.
918 Note that it can return a negative value if the bufferevent has been
919 made to read or write more than its limit.
920
921 @{
922 */
923EVENT2_EXPORT_SYMBOL
924ev_ssize_t bufferevent_get_read_limit(struct bufferevent *bev);
925EVENT2_EXPORT_SYMBOL
926ev_ssize_t bufferevent_get_write_limit(struct bufferevent *bev);
927/*@}*/
928
929EVENT2_EXPORT_SYMBOL
930ev_ssize_t bufferevent_get_max_to_read(struct bufferevent *bev);
931EVENT2_EXPORT_SYMBOL
932ev_ssize_t bufferevent_get_max_to_write(struct bufferevent *bev);
933
934EVENT2_EXPORT_SYMBOL
935const struct ev_token_bucket_cfg *bufferevent_get_token_bucket_cfg(const struct bufferevent * bev);
936
937/**
938 @name Group Rate limit inspection
939
940 Return the read or write bucket size for a bufferevent rate limit
941 group. Note that it can return a negative value if bufferevents in
942 the group have been made to read or write more than their limits.
943
944 @{
945 */
946EVENT2_EXPORT_SYMBOL
947ev_ssize_t bufferevent_rate_limit_group_get_read_limit(
948 struct bufferevent_rate_limit_group *);
949EVENT2_EXPORT_SYMBOL
950ev_ssize_t bufferevent_rate_limit_group_get_write_limit(
951 struct bufferevent_rate_limit_group *);
952/*@}*/
953
954/**
955 @name Rate limit manipulation
956
957 Subtract a number of bytes from a bufferevent's read or write bucket.
958 The decrement value can be negative, if you want to manually refill
959 the bucket. If the change puts the bucket above or below zero, the
960 bufferevent will resume or suspend reading writing as appropriate.
961 These functions make no change in the buckets for the bufferevent's
962 group, if any.
963
964 Returns 0 on success, -1 on internal error.
965
966 @{
967 */
968EVENT2_EXPORT_SYMBOL
969int bufferevent_decrement_read_limit(struct bufferevent *bev, ev_ssize_t decr);
970EVENT2_EXPORT_SYMBOL
971int bufferevent_decrement_write_limit(struct bufferevent *bev, ev_ssize_t decr);
972/*@}*/
973
974/**
975 @name Group rate limit manipulation
976
977 Subtract a number of bytes from a bufferevent rate-limiting group's
978 read or write bucket. The decrement value can be negative, if you
979 want to manually refill the bucket. If the change puts the bucket
980 above or below zero, the bufferevents in the group will resume or
981 suspend reading writing as appropriate.
982
983 Returns 0 on success, -1 on internal error.
984
985 @{
986 */
987EVENT2_EXPORT_SYMBOL
988int bufferevent_rate_limit_group_decrement_read(
989 struct bufferevent_rate_limit_group *, ev_ssize_t);
990EVENT2_EXPORT_SYMBOL
991int bufferevent_rate_limit_group_decrement_write(
992 struct bufferevent_rate_limit_group *, ev_ssize_t);
993/*@}*/
994
995
996/**
997 * Inspect the total bytes read/written on a group.
998 *
999 * Set the variable pointed to by total_read_out to the total number of bytes
1000 * ever read on grp, and the variable pointed to by total_written_out to the
1001 * total number of bytes ever written on grp. */
1002EVENT2_EXPORT_SYMBOL
1003void bufferevent_rate_limit_group_get_totals(
1004 struct bufferevent_rate_limit_group *grp,
1005 ev_uint64_t *total_read_out, ev_uint64_t *total_written_out);
1006
1007/**
1008 * Reset the total bytes read/written on a group.
1009 *
1010 * Reset the number of bytes read or written on grp as given by
1011 * bufferevent_rate_limit_group_reset_totals(). */
1012EVENT2_EXPORT_SYMBOL
1013void
1014bufferevent_rate_limit_group_reset_totals(
1015 struct bufferevent_rate_limit_group *grp);
1016
1017#ifdef __cplusplus
1018}
1019#endif
1020
1021#endif /* EVENT2_BUFFEREVENT_H_INCLUDED_ */
1022