1 /* $NetBSD: bufferevent-internal.h,v 1.5 2021/04/10 19:02:37 rillig Exp $ */ 2 3 /* 4 * Copyright (c) 2008-2012 Niels Provos and Nick Mathewson 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. The name of the author may not be used to endorse or promote products 15 * derived from this software without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 */ 28 #ifndef BUFFEREVENT_INTERNAL_H_INCLUDED_ 29 #define BUFFEREVENT_INTERNAL_H_INCLUDED_ 30 31 #ifdef __cplusplus 32 extern "C" { 33 #endif 34 35 #include "event2/event-config.h" 36 #include "event2/event_struct.h" 37 #include "evconfig-private.h" 38 #include "event2/util.h" 39 #include "defer-internal.h" 40 #include "evthread-internal.h" 41 #include "event2/thread.h" 42 #include "ratelim-internal.h" 43 #include "event2/bufferevent_struct.h" 44 45 #include "ipv6-internal.h" 46 #ifdef _WIN32 47 #include <ws2tcpip.h> 48 #endif 49 #ifdef EVENT__HAVE_NETINET_IN_H 50 #include <netinet/in.h> 51 #endif 52 #ifdef EVENT__HAVE_NETINET_IN6_H 53 #include <netinet/in6.h> 54 #endif 55 56 /* These flags are reasons that we might be declining to actually enable 57 reading or writing on a bufferevent. 58 */ 59 60 /* On a all bufferevents, for reading: used when we have read up to the 61 watermark value. 62 63 On a filtering bufferevent, for writing: used when the underlying 64 bufferevent's write buffer has been filled up to its watermark 65 value. 66 */ 67 #define BEV_SUSPEND_WM 0x01 68 /* On a base bufferevent: when we have emptied a bandwidth buckets */ 69 #define BEV_SUSPEND_BW 0x02 70 /* On a base bufferevent: when we have emptied the group's bandwidth bucket. */ 71 #define BEV_SUSPEND_BW_GROUP 0x04 72 /* On a socket bufferevent: can't do any operations while we're waiting for 73 * name lookup to finish. */ 74 #define BEV_SUSPEND_LOOKUP 0x08 75 /* On a base bufferevent, for reading: used when a filter has choked this 76 * (underlying) bufferevent because it has stopped reading from it. */ 77 #define BEV_SUSPEND_FILT_READ 0x10 78 79 typedef ev_uint16_t bufferevent_suspend_flags; 80 81 struct bufferevent_rate_limit_group { 82 /** List of all members in the group */ 83 LIST_HEAD(rlim_group_member_list, bufferevent_private) members; 84 /** Current limits for the group. */ 85 struct ev_token_bucket rate_limit; 86 struct ev_token_bucket_cfg rate_limit_cfg; 87 88 /** True iff we don't want to read from any member of the group.until 89 * the token bucket refills. */ 90 unsigned read_suspended : 1; 91 /** True iff we don't want to write from any member of the group.until 92 * the token bucket refills. */ 93 unsigned write_suspended : 1; 94 /** True iff we were unable to suspend one of the bufferevents in the 95 * group for reading the last time we tried, and we should try 96 * again. */ 97 unsigned pending_unsuspend_read : 1; 98 /** True iff we were unable to suspend one of the bufferevents in the 99 * group for writing the last time we tried, and we should try 100 * again. */ 101 unsigned pending_unsuspend_write : 1; 102 103 /*@{*/ 104 /** Total number of bytes read or written in this group since last 105 * reset. */ 106 ev_uint64_t total_read; 107 ev_uint64_t total_written; 108 /*@}*/ 109 110 /** The number of bufferevents in the group. */ 111 int n_members; 112 113 /** The smallest number of bytes that any member of the group should 114 * be limited to read or write at a time. */ 115 ev_ssize_t min_share; 116 ev_ssize_t configured_min_share; 117 118 /** Timeout event that goes off once a tick, when the bucket is ready 119 * to refill. */ 120 struct event master_refill_event; 121 122 /** Seed for weak random number generator. Protected by 'lock' */ 123 struct evutil_weakrand_state weakrand_seed; 124 125 /** Lock to protect the members of this group. This lock should nest 126 * within every bufferevent lock: if you are holding this lock, do 127 * not assume you can lock another bufferevent. */ 128 void *lock; 129 }; 130 131 /** Fields for rate-limiting a single bufferevent. */ 132 struct bufferevent_rate_limit { 133 /* Linked-list elements for storing this bufferevent_private in a 134 * group. 135 * 136 * Note that this field is supposed to be protected by the group 137 * lock */ 138 LIST_ENTRY(bufferevent_private) next_in_group; 139 /** The rate-limiting group for this bufferevent, or NULL if it is 140 * only rate-limited on its own. */ 141 struct bufferevent_rate_limit_group *group; 142 143 /* This bufferevent's current limits. */ 144 struct ev_token_bucket limit; 145 /* Pointer to the rate-limit configuration for this bufferevent. 146 * Can be shared. XXX reference-count this? */ 147 struct ev_token_bucket_cfg *cfg; 148 149 /* Timeout event used when one this bufferevent's buckets are 150 * empty. */ 151 struct event refill_bucket_event; 152 }; 153 154 /** Parts of the bufferevent structure that are shared among all bufferevent 155 * types, but not exposed in bufferevent_struct.h. */ 156 struct bufferevent_private { 157 /** The underlying bufferevent structure. */ 158 struct bufferevent bev; 159 160 /** Evbuffer callback to enforce watermarks on input. */ 161 struct evbuffer_cb_entry *read_watermarks_cb; 162 163 /** If set, we should free the lock when we free the bufferevent. */ 164 unsigned own_lock : 1; 165 166 /** Flag: set if we have deferred callbacks and a read callback is 167 * pending. */ 168 unsigned readcb_pending : 1; 169 /** Flag: set if we have deferred callbacks and a write callback is 170 * pending. */ 171 unsigned writecb_pending : 1; 172 /** Flag: set if we are currently busy connecting. */ 173 unsigned connecting : 1; 174 /** Flag: set if a connect failed prematurely; this is a hack for 175 * getting around the bufferevent abstraction. */ 176 unsigned connection_refused : 1; 177 /** Set to the events pending if we have deferred callbacks and 178 * an events callback is pending. */ 179 short eventcb_pending; 180 181 /** If set, read is suspended until one or more conditions are over. 182 * The actual value here is a bitfield of those conditions; see the 183 * BEV_SUSPEND_* flags above. */ 184 bufferevent_suspend_flags read_suspended; 185 186 /** If set, writing is suspended until one or more conditions are over. 187 * The actual value here is a bitfield of those conditions; see the 188 * BEV_SUSPEND_* flags above. */ 189 bufferevent_suspend_flags write_suspended; 190 191 /** Set to the current socket errno if we have deferred callbacks and 192 * an events callback is pending. */ 193 int errno_pending; 194 195 /** The DNS error code for bufferevent_socket_connect_hostname */ 196 int dns_error; 197 198 /** Used to implement deferred callbacks */ 199 struct event_callback deferred; 200 201 /** The options this bufferevent was constructed with */ 202 enum bufferevent_options options; 203 204 /** Current reference count for this bufferevent. */ 205 int refcnt; 206 207 /** Lock for this bufferevent. Shared by the inbuf and the outbuf. 208 * If NULL, locking is disabled. */ 209 void *lock; 210 211 /** No matter how big our bucket gets, don't try to read more than this 212 * much in a single read operation. */ 213 ev_ssize_t max_single_read; 214 215 /** No matter how big our bucket gets, don't try to write more than this 216 * much in a single write operation. */ 217 ev_ssize_t max_single_write; 218 219 /** Rate-limiting information for this bufferevent */ 220 struct bufferevent_rate_limit *rate_limiting; 221 222 /* Saved conn_addr, to extract IP address from it. 223 * 224 * Because some servers may reset/close connection without waiting clients, 225 * in that case we can't extract IP address even in close_cb. 226 * So we need to save it, just after we connected to remote server, or 227 * after resolving (to avoid extra dns requests during retrying, since UDP 228 * is slow) */ 229 union { 230 struct sockaddr_in6 in6; 231 struct sockaddr_in in; 232 } conn_address; 233 234 struct evdns_getaddrinfo_request *dns_request; 235 }; 236 237 /** Possible operations for a control callback. */ 238 enum bufferevent_ctrl_op { 239 BEV_CTRL_SET_FD, 240 BEV_CTRL_GET_FD, 241 BEV_CTRL_GET_UNDERLYING, 242 BEV_CTRL_CANCEL_ALL 243 }; 244 245 /** Possible data types for a control callback */ 246 union bufferevent_ctrl_data { 247 void *ptr; 248 evutil_socket_t fd; 249 }; 250 251 /** 252 Implementation table for a bufferevent: holds function pointers and other 253 information to make the various bufferevent types work. 254 */ 255 struct bufferevent_ops { 256 /** The name of the bufferevent's type. */ 257 const char *type; 258 /** At what offset into the implementation type will we find a 259 bufferevent structure? 260 261 Example: if the type is implemented as 262 struct bufferevent_x { 263 int extra_data; 264 struct bufferevent bev; 265 } 266 then mem_offset should be offsetof(struct bufferevent_x, bev) 267 */ 268 off_t mem_offset; 269 270 /** Enables one or more of EV_READ|EV_WRITE on a bufferevent. Does 271 not need to adjust the 'enabled' field. Returns 0 on success, -1 272 on failure. 273 */ 274 int (*enable)(struct bufferevent *, short); 275 276 /** Disables one or more of EV_READ|EV_WRITE on a bufferevent. Does 277 not need to adjust the 'enabled' field. Returns 0 on success, -1 278 on failure. 279 */ 280 int (*disable)(struct bufferevent *, short); 281 282 /** Detatches the bufferevent from related data structures. Called as 283 * soon as its reference count reaches 0. */ 284 void (*unlink)(struct bufferevent *); 285 286 /** Free any storage and deallocate any extra data or structures used 287 in this implementation. Called when the bufferevent is 288 finalized. 289 */ 290 void (*destruct)(struct bufferevent *); 291 292 /** Called when the timeouts on the bufferevent have changed.*/ 293 int (*adj_timeouts)(struct bufferevent *); 294 295 /** Called to flush data. */ 296 int (*flush)(struct bufferevent *, short, enum bufferevent_flush_mode); 297 298 /** Called to access miscellaneous fields. */ 299 int (*ctrl)(struct bufferevent *, enum bufferevent_ctrl_op, union bufferevent_ctrl_data *); 300 301 }; 302 303 extern const struct bufferevent_ops bufferevent_ops_socket; 304 extern const struct bufferevent_ops bufferevent_ops_filter; 305 extern const struct bufferevent_ops bufferevent_ops_pair; 306 307 #define BEV_IS_SOCKET(bevp) ((bevp)->be_ops == &bufferevent_ops_socket) 308 #define BEV_IS_FILTER(bevp) ((bevp)->be_ops == &bufferevent_ops_filter) 309 #define BEV_IS_PAIR(bevp) ((bevp)->be_ops == &bufferevent_ops_pair) 310 311 #if defined(EVENT__HAVE_OPENSSL) 312 extern const struct bufferevent_ops bufferevent_ops_openssl; 313 #define BEV_IS_OPENSSL(bevp) ((bevp)->be_ops == &bufferevent_ops_openssl) 314 #else 315 #define BEV_IS_OPENSSL(bevp) 0 316 #endif 317 318 #ifdef _WIN32 319 extern const struct bufferevent_ops bufferevent_ops_async; 320 #define BEV_IS_ASYNC(bevp) ((bevp)->be_ops == &bufferevent_ops_async) 321 #else 322 #define BEV_IS_ASYNC(bevp) 0 323 #endif 324 325 /** Initialize the shared parts of a bufferevent. */ 326 EVENT2_EXPORT_SYMBOL 327 int bufferevent_init_common_(struct bufferevent_private *, struct event_base *, const struct bufferevent_ops *, enum bufferevent_options options); 328 329 /** For internal use: temporarily stop all reads on bufev, until the conditions 330 * in 'what' are over. */ 331 EVENT2_EXPORT_SYMBOL 332 void bufferevent_suspend_read_(struct bufferevent *bufev, bufferevent_suspend_flags what); 333 /** For internal use: clear the conditions 'what' on bufev, and re-enable 334 * reading if there are no conditions left. */ 335 EVENT2_EXPORT_SYMBOL 336 void bufferevent_unsuspend_read_(struct bufferevent *bufev, bufferevent_suspend_flags what); 337 338 /** For internal use: temporarily stop all writes on bufev, until the conditions 339 * in 'what' are over. */ 340 void bufferevent_suspend_write_(struct bufferevent *bufev, bufferevent_suspend_flags what); 341 /** For internal use: clear the conditions 'what' on bufev, and re-enable 342 * writing if there are no conditions left. */ 343 void bufferevent_unsuspend_write_(struct bufferevent *bufev, bufferevent_suspend_flags what); 344 345 #define bufferevent_wm_suspend_read(b) \ 346 bufferevent_suspend_read_((b), BEV_SUSPEND_WM) 347 #define bufferevent_wm_unsuspend_read(b) \ 348 bufferevent_unsuspend_read_((b), BEV_SUSPEND_WM) 349 350 /* 351 Disable a bufferevent. Equivalent to bufferevent_disable(), but 352 first resets 'connecting' flag to force EV_WRITE down for sure. 353 354 XXXX this method will go away in the future; try not to add new users. 355 See comment in evhttp_connection_reset_() for discussion. 356 357 @param bufev the bufferevent to be disabled 358 @param event any combination of EV_READ | EV_WRITE. 359 @return 0 if successful, or -1 if an error occurred 360 @see bufferevent_disable() 361 */ 362 EVENT2_EXPORT_SYMBOL 363 int bufferevent_disable_hard_(struct bufferevent *bufev, short event); 364 365 /** Internal: Set up locking on a bufferevent. If lock is set, use it. 366 * Otherwise, use a new lock. */ 367 EVENT2_EXPORT_SYMBOL 368 int bufferevent_enable_locking_(struct bufferevent *bufev, void *lock); 369 /** Internal: backwards compat macro for the now public function 370 * Increment the reference count on bufev. */ 371 #define bufferevent_incref_(bufev) bufferevent_incref(bufev) 372 /** Internal: Lock bufev and increase its reference count. 373 * unlocking it otherwise. */ 374 EVENT2_EXPORT_SYMBOL 375 void bufferevent_incref_and_lock_(struct bufferevent *bufev); 376 /** Internal: backwards compat macro for the now public function 377 * Decrement the reference count on bufev. Returns 1 if it freed 378 * the bufferevent.*/ 379 #define bufferevent_decref_(bufev) bufferevent_decref(bufev) 380 381 /** Internal: Drop the reference count on bufev, freeing as necessary, and 382 * unlocking it otherwise. Returns 1 if it freed the bufferevent. */ 383 EVENT2_EXPORT_SYMBOL 384 int bufferevent_decref_and_unlock_(struct bufferevent *bufev); 385 386 /** Internal: If callbacks are deferred and we have a read callback, schedule 387 * a readcb. Otherwise just run the readcb. Ignores watermarks. */ 388 EVENT2_EXPORT_SYMBOL 389 void bufferevent_run_readcb_(struct bufferevent *bufev, int options); 390 /** Internal: If callbacks are deferred and we have a write callback, schedule 391 * a writecb. Otherwise just run the writecb. Ignores watermarks. */ 392 EVENT2_EXPORT_SYMBOL 393 void bufferevent_run_writecb_(struct bufferevent *bufev, int options); 394 /** Internal: If callbacks are deferred and we have an eventcb, schedule 395 * it to run with events "what". Otherwise just run the eventcb. 396 * See bufferevent_trigger_event for meaning of "options". */ 397 EVENT2_EXPORT_SYMBOL 398 void bufferevent_run_eventcb_(struct bufferevent *bufev, short what, int options); 399 400 /** Internal: Run or schedule (if deferred or options contain 401 * BEV_TRIG_DEFER_CALLBACKS) I/O callbacks specified in iotype. 402 * Must already hold the bufev lock. Honors watermarks unless 403 * BEV_TRIG_IGNORE_WATERMARKS is in options. */ 404 static inline void bufferevent_trigger_nolock_(struct bufferevent *bufev, short iotype, int options); 405 406 /* Making this inline since all of the common-case calls to this function in 407 * libevent use constant arguments. */ 408 static inline void 409 bufferevent_trigger_nolock_(struct bufferevent *bufev, short iotype, int options) 410 { 411 if ((iotype & EV_READ) && ((options & BEV_TRIG_IGNORE_WATERMARKS) || 412 evbuffer_get_length(bufev->input) >= bufev->wm_read.low)) 413 bufferevent_run_readcb_(bufev, options); 414 if ((iotype & EV_WRITE) && ((options & BEV_TRIG_IGNORE_WATERMARKS) || 415 evbuffer_get_length(bufev->output) <= bufev->wm_write.low)) 416 bufferevent_run_writecb_(bufev, options); 417 } 418 419 /** Internal: Add the event 'ev' with timeout tv, unless tv is set to 0, in 420 * which case add ev with no timeout. */ 421 EVENT2_EXPORT_SYMBOL 422 int bufferevent_add_event_(struct event *ev, const struct timeval *tv); 423 424 /* ========= 425 * These next functions implement timeouts for bufferevents that aren't doing 426 * anything else with ev_read and ev_write, to handle timeouts. 427 * ========= */ 428 /** Internal use: Set up the ev_read and ev_write callbacks so that 429 * the other "generic_timeout" functions will work on it. Call this from 430 * the constructor function. */ 431 EVENT2_EXPORT_SYMBOL 432 void bufferevent_init_generic_timeout_cbs_(struct bufferevent *bev); 433 /** Internal use: Add or delete the generic timeout events as appropriate. 434 * (If an event is enabled and a timeout is set, we add the event. Otherwise 435 * we delete it.) Call this from anything that changes the timeout values, 436 * that enabled EV_READ or EV_WRITE, or that disables EV_READ or EV_WRITE. */ 437 EVENT2_EXPORT_SYMBOL 438 int bufferevent_generic_adj_timeouts_(struct bufferevent *bev); 439 EVENT2_EXPORT_SYMBOL 440 int bufferevent_generic_adj_existing_timeouts_(struct bufferevent *bev); 441 442 EVENT2_EXPORT_SYMBOL 443 enum bufferevent_options bufferevent_get_options_(struct bufferevent *bev); 444 445 EVENT2_EXPORT_SYMBOL 446 const struct sockaddr* 447 bufferevent_socket_get_conn_address_(struct bufferevent *bev); 448 449 EVENT2_EXPORT_SYMBOL 450 void 451 bufferevent_socket_set_conn_address_fd_(struct bufferevent *bev, evutil_socket_t fd); 452 453 EVENT2_EXPORT_SYMBOL 454 void 455 bufferevent_socket_set_conn_address_(struct bufferevent *bev, struct sockaddr *addr, size_t addrlen); 456 457 458 /** Internal use: We have just successfully read data into an inbuf, so 459 * reset the read timeout (if any). */ 460 #define BEV_RESET_GENERIC_READ_TIMEOUT(bev) \ 461 do { \ 462 if (evutil_timerisset(&(bev)->timeout_read)) \ 463 event_add(&(bev)->ev_read, &(bev)->timeout_read); \ 464 } while (0) 465 /** Internal use: We have just successfully written data from an inbuf, so 466 * reset the read timeout (if any). */ 467 #define BEV_RESET_GENERIC_WRITE_TIMEOUT(bev) \ 468 do { \ 469 if (evutil_timerisset(&(bev)->timeout_write)) \ 470 event_add(&(bev)->ev_write, &(bev)->timeout_write); \ 471 } while (0) 472 #define BEV_DEL_GENERIC_READ_TIMEOUT(bev) \ 473 event_del(&(bev)->ev_read) 474 #define BEV_DEL_GENERIC_WRITE_TIMEOUT(bev) \ 475 event_del(&(bev)->ev_write) 476 477 478 /** Internal: Given a bufferevent, return its corresponding 479 * bufferevent_private. */ 480 #define BEV_UPCAST(b) EVUTIL_UPCAST((b), struct bufferevent_private, bev) 481 482 #ifdef EVENT__DISABLE_THREAD_SUPPORT 483 #define BEV_LOCK(b) EVUTIL_NIL_STMT_ 484 #define BEV_UNLOCK(b) EVUTIL_NIL_STMT_ 485 #else 486 /** Internal: Grab the lock (if any) on a bufferevent */ 487 #define BEV_LOCK(b) do { \ 488 struct bufferevent_private *locking = BEV_UPCAST(b); \ 489 EVLOCK_LOCK(locking->lock, 0); \ 490 } while (0) 491 492 /** Internal: Release the lock (if any) on a bufferevent */ 493 #define BEV_UNLOCK(b) do { \ 494 struct bufferevent_private *locking = BEV_UPCAST(b); \ 495 EVLOCK_UNLOCK(locking->lock, 0); \ 496 } while (0) 497 #endif 498 499 500 /* ==== For rate-limiting. */ 501 502 EVENT2_EXPORT_SYMBOL 503 int bufferevent_decrement_write_buckets_(struct bufferevent_private *bev, 504 ev_ssize_t bytes); 505 EVENT2_EXPORT_SYMBOL 506 int bufferevent_decrement_read_buckets_(struct bufferevent_private *bev, 507 ev_ssize_t bytes); 508 EVENT2_EXPORT_SYMBOL 509 ev_ssize_t bufferevent_get_read_max_(struct bufferevent_private *bev); 510 EVENT2_EXPORT_SYMBOL 511 ev_ssize_t bufferevent_get_write_max_(struct bufferevent_private *bev); 512 513 int bufferevent_ratelim_init_(struct bufferevent_private *bev); 514 515 #ifdef __cplusplus 516 } 517 #endif 518 519 520 #endif /* BUFFEREVENT_INTERNAL_H_INCLUDED_ */ 521