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