1 /* $NetBSD: bufferevent-internal.h,v 1.6 2024/08/18 20:47:20 christos 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
bufferevent_trigger_nolock_(struct bufferevent * bufev,short iotype,int options)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