1 /* 2 * Copyright (c) 2000-2007 Niels Provos <provos (at) 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 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 */ 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. 521 522 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 */ 532 533 EVENT2_EXPORT_SYMBOL 534 void 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 */ 547 EVENT2_EXPORT_SYMBOL 548 int 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 */ 555 EVENT2_EXPORT_SYMBOL 556 void 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 */ 562 EVENT2_EXPORT_SYMBOL 563 void 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 */ 574 EVENT2_EXPORT_SYMBOL 575 void 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 */ 588 EVENT2_EXPORT_SYMBOL 589 int 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 */ 595 enum 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 */ 614 EVENT2_EXPORT_SYMBOL 615 int 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 */ 623 enum 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 */ 645 EVENT2_EXPORT_SYMBOL 646 void 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 */ 658 EVENT2_EXPORT_SYMBOL 659 void 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 */ 670 enum 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 */ 700 typedef 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 */ 717 EVENT2_EXPORT_SYMBOL 718 struct bufferevent * 719 bufferevent_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 */ 737 EVENT2_EXPORT_SYMBOL 738 int 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 */ 745 EVENT2_EXPORT_SYMBOL 746 struct 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 */ 752 struct ev_token_bucket_cfg; 753 754 /** 755 A group of bufferevents which are configured to respect the same rate 756 limit. 757 */ 758 struct 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 */ 779 EVENT2_EXPORT_SYMBOL 780 struct 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 */ 790 EVENT2_EXPORT_SYMBOL 791 void 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 */ 804 EVENT2_EXPORT_SYMBOL 805 int 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 */ 825 EVENT2_EXPORT_SYMBOL 826 struct 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 */ 834 EVENT2_EXPORT_SYMBOL 835 int 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 */ 855 EVENT2_EXPORT_SYMBOL 856 int 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 */ 863 EVENT2_EXPORT_SYMBOL 864 void 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 */ 876 EVENT2_EXPORT_SYMBOL 877 int 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). */ 881 EVENT2_EXPORT_SYMBOL 882 int 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 */ 891 EVENT2_EXPORT_SYMBOL 892 int 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 */ 901 EVENT2_EXPORT_SYMBOL 902 int bufferevent_set_max_single_write(struct bufferevent *bev, size_t size); 903 904 /** Get the current size limit for single read operation. */ 905 EVENT2_EXPORT_SYMBOL 906 ev_ssize_t bufferevent_get_max_single_read(struct bufferevent *bev); 907 908 /** Get the current size limit for single write operation. */ 909 EVENT2_EXPORT_SYMBOL 910 ev_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 */ 923 EVENT2_EXPORT_SYMBOL 924 ev_ssize_t bufferevent_get_read_limit(struct bufferevent *bev); 925 EVENT2_EXPORT_SYMBOL 926 ev_ssize_t bufferevent_get_write_limit(struct bufferevent *bev); 927 /*@}*/ 928 929 EVENT2_EXPORT_SYMBOL 930 ev_ssize_t bufferevent_get_max_to_read(struct bufferevent *bev); 931 EVENT2_EXPORT_SYMBOL 932 ev_ssize_t bufferevent_get_max_to_write(struct bufferevent *bev); 933 934 EVENT2_EXPORT_SYMBOL 935 const 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 */ 946 EVENT2_EXPORT_SYMBOL 947 ev_ssize_t bufferevent_rate_limit_group_get_read_limit( 948 struct bufferevent_rate_limit_group *); 949 EVENT2_EXPORT_SYMBOL 950 ev_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 */ 968 EVENT2_EXPORT_SYMBOL 969 int bufferevent_decrement_read_limit(struct bufferevent *bev, ev_ssize_t decr); 970 EVENT2_EXPORT_SYMBOL 971 int 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 */ 987 EVENT2_EXPORT_SYMBOL 988 int bufferevent_rate_limit_group_decrement_read( 989 struct bufferevent_rate_limit_group *, ev_ssize_t); 990 EVENT2_EXPORT_SYMBOL 991 int 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. */ 1002 EVENT2_EXPORT_SYMBOL 1003 void 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(). */ 1012 EVENT2_EXPORT_SYMBOL 1013 void 1014 bufferevent_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
