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 80 extern "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 */ 113 struct bufferevent 114 #ifdef EVENT_IN_DOXYGEN_ 115 {} 116 #endif 117 ; 118 struct event_base; 119 struct evbuffer; 120 struct 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 */ 135 typedef 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 */ 154 typedef void (*bufferevent_event_cb)(struct bufferevent *bev, short what, void *ctx); 155 156 /** Options that can be specified when creating a bufferevent */ 157 enum 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 */ 189 EVENT2_EXPORT_SYMBOL 190 struct 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 */ 211 EVENT2_EXPORT_SYMBOL 212 int bufferevent_socket_connect(struct bufferevent *, const struct sockaddr *, int); 213 214 struct 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 */ 241 EVENT2_EXPORT_SYMBOL 242 int 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 */ 253 EVENT2_EXPORT_SYMBOL 254 int 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 */ 267 EVENT2_EXPORT_SYMBOL 268 int bufferevent_base_set(struct event_base *base, struct bufferevent *bufev); 269 270 /** 271 Return the event_base used by a bufferevent 272 */ 273 EVENT2_EXPORT_SYMBOL 274 struct 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 */ 285 EVENT2_EXPORT_SYMBOL 286 int 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 */ 293 EVENT2_EXPORT_SYMBOL 294 int 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 */ 304 EVENT2_EXPORT_SYMBOL 305 void 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 */ 322 EVENT2_EXPORT_SYMBOL 323 void 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 */ 341 EVENT2_EXPORT_SYMBOL 342 void 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 */ 355 EVENT2_EXPORT_SYMBOL 356 int 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 */ 362 EVENT2_EXPORT_SYMBOL 363 evutil_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 */ 369 EVENT2_EXPORT_SYMBOL 370 struct 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 */ 385 EVENT2_EXPORT_SYMBOL 386 int 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 */ 399 EVENT2_EXPORT_SYMBOL 400 int 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 */ 413 EVENT2_EXPORT_SYMBOL 414 size_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 */ 424 EVENT2_EXPORT_SYMBOL 425 int 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 */ 435 436 EVENT2_EXPORT_SYMBOL 437 struct 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 */ 450 451 EVENT2_EXPORT_SYMBOL 452 struct 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 */ 462 EVENT2_EXPORT_SYMBOL 463 int 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 */ 473 EVENT2_EXPORT_SYMBOL 474 int 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 */ 482 EVENT2_EXPORT_SYMBOL 483 short 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 */ 511 EVENT2_EXPORT_SYMBOL 512 int 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 */ 535 536 EVENT2_EXPORT_SYMBOL 537 void 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 */ 550 EVENT2_EXPORT_SYMBOL 551 int 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 */ 558 EVENT2_EXPORT_SYMBOL 559 void 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 */ 565 EVENT2_EXPORT_SYMBOL 566 void 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 */ 577 EVENT2_EXPORT_SYMBOL 578 void 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 */ 591 EVENT2_EXPORT_SYMBOL 592 int 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 */ 598 enum 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 */ 617 EVENT2_EXPORT_SYMBOL 618 int 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 */ 626 enum 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 */ 648 EVENT2_EXPORT_SYMBOL 649 void 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 */ 661 EVENT2_EXPORT_SYMBOL 662 void 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 */ 673 enum 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 */ 703 typedef 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 */ 720 EVENT2_EXPORT_SYMBOL 721 struct bufferevent * 722 bufferevent_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 */ 740 EVENT2_EXPORT_SYMBOL 741 int 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 */ 748 EVENT2_EXPORT_SYMBOL 749 struct 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 */ 755 struct ev_token_bucket_cfg; 756 757 /** 758 A group of bufferevents which are configured to respect the same rate 759 limit. 760 */ 761 struct 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 */ 782 EVENT2_EXPORT_SYMBOL 783 struct 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 */ 793 EVENT2_EXPORT_SYMBOL 794 void 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 */ 807 EVENT2_EXPORT_SYMBOL 808 int 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 */ 828 EVENT2_EXPORT_SYMBOL 829 struct 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 */ 837 EVENT2_EXPORT_SYMBOL 838 int 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 */ 858 EVENT2_EXPORT_SYMBOL 859 int 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 */ 866 EVENT2_EXPORT_SYMBOL 867 void 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 */ 879 EVENT2_EXPORT_SYMBOL 880 int 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). */ 884 EVENT2_EXPORT_SYMBOL 885 int 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 */ 894 EVENT2_EXPORT_SYMBOL 895 int 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 */ 904 EVENT2_EXPORT_SYMBOL 905 int bufferevent_set_max_single_write(struct bufferevent *bev, size_t size); 906 907 /** Get the current size limit for single read operation. */ 908 EVENT2_EXPORT_SYMBOL 909 ev_ssize_t bufferevent_get_max_single_read(struct bufferevent *bev); 910 911 /** Get the current size limit for single write operation. */ 912 EVENT2_EXPORT_SYMBOL 913 ev_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 */ 926 EVENT2_EXPORT_SYMBOL 927 ev_ssize_t bufferevent_get_read_limit(struct bufferevent *bev); 928 EVENT2_EXPORT_SYMBOL 929 ev_ssize_t bufferevent_get_write_limit(struct bufferevent *bev); 930 /*@}*/ 931 932 EVENT2_EXPORT_SYMBOL 933 ev_ssize_t bufferevent_get_max_to_read(struct bufferevent *bev); 934 EVENT2_EXPORT_SYMBOL 935 ev_ssize_t bufferevent_get_max_to_write(struct bufferevent *bev); 936 937 EVENT2_EXPORT_SYMBOL 938 const 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 */ 949 EVENT2_EXPORT_SYMBOL 950 ev_ssize_t bufferevent_rate_limit_group_get_read_limit( 951 struct bufferevent_rate_limit_group *); 952 EVENT2_EXPORT_SYMBOL 953 ev_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 */ 971 EVENT2_EXPORT_SYMBOL 972 int bufferevent_decrement_read_limit(struct bufferevent *bev, ev_ssize_t decr); 973 EVENT2_EXPORT_SYMBOL 974 int 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 */ 990 EVENT2_EXPORT_SYMBOL 991 int bufferevent_rate_limit_group_decrement_read( 992 struct bufferevent_rate_limit_group *, ev_ssize_t); 993 EVENT2_EXPORT_SYMBOL 994 int 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. */ 1005 EVENT2_EXPORT_SYMBOL 1006 void 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(). */ 1015 EVENT2_EXPORT_SYMBOL 1016 void 1017 bufferevent_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