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_
27 #define _BUFFEREVENT_INTERNAL_H_
28
29 #ifdef __cplusplus
30 extern "C" {
31 #endif
32
33 #include "event2/event-config.h"
34 #include "event2/util.h"
35 #include "defer-internal.h"
36 #include "evthread-internal.h"
37 #include "event2/thread.h"
38 #include "ratelim-internal.h"
39 #include "event2/bufferevent_struct.h"
40
41 /* These flags are reasons that we might be declining to actually enable
42 reading or writing on a bufferevent.
43 */
44
45 /* On a all bufferevents, for reading: used when we have read up to the
46 watermark value.
47
48 On a filtering bufferevent, for writing: used when the underlying
49 bufferevent's write buffer has been filled up to its watermark
50 value.
51 */
52 #define BEV_SUSPEND_WM 0x01
53 /* On a base bufferevent: when we have emptied a bandwidth buckets */
54 #define BEV_SUSPEND_BW 0x02
55 /* On a base bufferevent: when we have emptied the group's bandwidth bucket. */
56 #define BEV_SUSPEND_BW_GROUP 0x04
57 /* On a socket bufferevent: can't do any operations while we're waiting for
58 * name lookup to finish. */
59 #define BEV_SUSPEND_LOOKUP 0x08
60 /* On a base bufferevent, for reading: used when a filter has choked this
61 * (underlying) bufferevent because it has stopped reading from it. */
62 #define BEV_SUSPEND_FILT_READ 0x10
63
64 typedef ev_uint16_t bufferevent_suspend_flags;
65
66 struct bufferevent_rate_limit_group {
67 /** List of all members in the group */
68 TAILQ_HEAD(rlim_group_member_list, bufferevent_private) members;
69 /** Current limits for the group. */
70 struct ev_token_bucket rate_limit;
71 struct ev_token_bucket_cfg rate_limit_cfg;
72
73 /** True iff we don't want to read from any member of the group.until
74 * the token bucket refills. */
75 unsigned read_suspended : 1;
76 /** True iff we don't want to write from any member of the group.until
77 * the token bucket refills. */
78 unsigned write_suspended : 1;
79 /** True iff we were unable to suspend one of the bufferevents in the
80 * group for reading the last time we tried, and we should try
81 * again. */
82 unsigned pending_unsuspend_read : 1;
83 /** True iff we were unable to suspend one of the bufferevents in the
84 * group for writing the last time we tried, and we should try
85 * again. */
86 unsigned pending_unsuspend_write : 1;
87
88 /*@{*/
89 /** Total number of bytes read or written in this group since last
90 * reset. */
91 ev_uint64_t total_read;
92 ev_uint64_t total_written;
93 /*@}*/
94
95 /** The number of bufferevents in the group. */
96 int n_members;
97
98 /** The smallest number of bytes that any member of the group should
99 * be limited to read or write at a time. */
100 ev_ssize_t min_share;
101 ev_ssize_t configured_min_share;
102
103 /** Timeout event that goes off once a tick, when the bucket is ready
104 * to refill. */
105 struct event master_refill_event;
106 /** Lock to protect the members of this group. This lock should nest
107 * within every bufferevent lock: if you are holding this lock, do
108 * not assume you can lock another bufferevent. */
109 void *lock;
110 };
111
112 /** Fields for rate-limiting a single bufferevent. */
113 struct bufferevent_rate_limit {
114 /* Linked-list elements for storing this bufferevent_private in a
115 * group.
116 *
117 * Note that this field is supposed to be protected by the group
118 * lock */
119 TAILQ_ENTRY(bufferevent_private) next_in_group;
120 /** The rate-limiting group for this bufferevent, or NULL if it is
121 * only rate-limited on its own. */
122 struct bufferevent_rate_limit_group *group;
123
124 /* This bufferevent's current limits. */
125 struct ev_token_bucket limit;
126 /* Pointer to the rate-limit configuration for this bufferevent.
127 * Can be shared. XXX reference-count this? */
128 struct ev_token_bucket_cfg *cfg;
129
130 /* Timeout event used when one this bufferevent's buckets are
131 * empty. */
132 struct event refill_bucket_event;
133 };
134
135 /** Parts of the bufferevent structure that are shared among all bufferevent
136 * types, but not exposed in bufferevent_struct.h. */
137 struct bufferevent_private {
138 /** The underlying bufferevent structure. */
139 struct bufferevent bev;
140
141 /** Evbuffer callback to enforce watermarks on input. */
142 struct evbuffer_cb_entry *read_watermarks_cb;
143
144 /** If set, we should free the lock when we free the bufferevent. */
145 unsigned own_lock : 1;
146
147 /** Flag: set if we have deferred callbacks and a read callback is
148 * pending. */
149 unsigned readcb_pending : 1;
150 /** Flag: set if we have deferred callbacks and a write callback is
151 * pending. */
152 unsigned writecb_pending : 1;
153 /** Flag: set if we are currently busy connecting. */
154 unsigned connecting : 1;
155 /** Flag: set if a connect failed prematurely; this is a hack for
156 * getting around the bufferevent abstraction. */
157 unsigned connection_refused : 1;
158 /** Set to the events pending if we have deferred callbacks and
159 * an events callback is pending. */
160 short eventcb_pending;
161
162 /** If set, read is suspended until one or more conditions are over.
163 * The actual value here is a bitfield of those conditions; see the
164 * BEV_SUSPEND_* flags above. */
165 bufferevent_suspend_flags read_suspended;
166
167 /** If set, writing is suspended until one or more conditions are over.
168 * The actual value here is a bitfield of those conditions; see the
169 * BEV_SUSPEND_* flags above. */
170 bufferevent_suspend_flags write_suspended;
171
172 /** Set to the current socket errno if we have deferred callbacks and
173 * an events callback is pending. */
174 int errno_pending;
175
176 /** The DNS error code for bufferevent_socket_connect_hostname */
177 int dns_error;
178
179 /** Used to implement deferred callbacks */
180 struct deferred_cb deferred;
181
182 /** The options this bufferevent was constructed with */
183 enum bufferevent_options options;
184
185 /** Current reference count for this bufferevent. */
186 int refcnt;
187
188 /** Lock for this bufferevent. Shared by the inbuf and the outbuf.
189 * If NULL, locking is disabled. */
190 void *lock;
191
192 /** Rate-limiting information for this bufferevent */
193 struct bufferevent_rate_limit *rate_limiting;
194 };
195
196 /** Possible operations for a control callback. */
197 enum bufferevent_ctrl_op {
198 BEV_CTRL_SET_FD,
199 BEV_CTRL_GET_FD,
200 BEV_CTRL_GET_UNDERLYING,
201 BEV_CTRL_CANCEL_ALL
202 };
203
204 /** Possible data types for a control callback */
205 union bufferevent_ctrl_data {
206 void *ptr;
207 evutil_socket_t fd;
208 };
209
210 /**
211 Implementation table for a bufferevent: holds function pointers and other
212 information to make the various bufferevent types work.
213 */
214 struct bufferevent_ops {
215 /** The name of the bufferevent's type. */
216 const char *type;
217 /** At what offset into the implementation type will we find a
218 bufferevent structure?
219
220 Example: if the type is implemented as
221 struct bufferevent_x {
222 int extra_data;
223 struct bufferevent bev;
224 }
225 then mem_offset should be offsetof(struct bufferevent_x, bev)
226 */
227 off_t mem_offset;
228
229 /** Enables one or more of EV_READ|EV_WRITE on a bufferevent. Does
230 not need to adjust the 'enabled' field. Returns 0 on success, -1
231 on failure.
232 */
233 int (*enable)(struct bufferevent *, short);
234
235 /** Disables one or more of EV_READ|EV_WRITE on a bufferevent. Does
236 not need to adjust the 'enabled' field. Returns 0 on success, -1
237 on failure.
238 */
239 int (*disable)(struct bufferevent *, short);
240
241 /** Free any storage and deallocate any extra data or structures used
242 in this implementation.
243 */
244 void (*destruct)(struct bufferevent *);
245
246 /** Called when the timeouts on the bufferevent have changed.*/
247 int (*adj_timeouts)(struct bufferevent *);
248
249 /** Called to flush data. */
250 int (*flush)(struct bufferevent *, short, enum bufferevent_flush_mode);
251
252 /** Called to access miscellaneous fields. */
253 int (*ctrl)(struct bufferevent *, enum bufferevent_ctrl_op, union bufferevent_ctrl_data *);
254
255 };
256
257 extern const struct bufferevent_ops bufferevent_ops_socket;
258 extern const struct bufferevent_ops bufferevent_ops_filter;
259 extern const struct bufferevent_ops bufferevent_ops_pair;
260
261 #define BEV_IS_SOCKET(bevp) ((bevp)->be_ops == &bufferevent_ops_socket)
262 #define BEV_IS_FILTER(bevp) ((bevp)->be_ops == &bufferevent_ops_filter)
263 #define BEV_IS_PAIR(bevp) ((bevp)->be_ops == &bufferevent_ops_pair)
264
265 #ifdef WIN32
266 extern const struct bufferevent_ops bufferevent_ops_async;
267 #define BEV_IS_ASYNC(bevp) ((bevp)->be_ops == &bufferevent_ops_async)
268 #else
269 #define BEV_IS_ASYNC(bevp) 0
270 #endif
271
272 /** Initialize the shared parts of a bufferevent. */
273 int bufferevent_init_common(struct bufferevent_private *, struct event_base *, const struct bufferevent_ops *, enum bufferevent_options options);
274
275 /** For internal use: temporarily stop all reads on bufev, until the conditions
276 * in 'what' are over. */
277 void bufferevent_suspend_read(struct bufferevent *bufev, bufferevent_suspend_flags what);
278 /** For internal use: clear the conditions 'what' on bufev, and re-enable
279 * reading if there are no conditions left. */
280 void bufferevent_unsuspend_read(struct bufferevent *bufev, bufferevent_suspend_flags what);
281
282 /** For internal use: temporarily stop all writes on bufev, until the conditions
283 * in 'what' are over. */
284 void bufferevent_suspend_write(struct bufferevent *bufev, bufferevent_suspend_flags what);
285 /** For internal use: clear the conditions 'what' on bufev, and re-enable
286 * writing if there are no conditions left. */
287 void bufferevent_unsuspend_write(struct bufferevent *bufev, bufferevent_suspend_flags what);
288
289 #define bufferevent_wm_suspend_read(b) \
290 bufferevent_suspend_read((b), BEV_SUSPEND_WM)
291 #define bufferevent_wm_unsuspend_read(b) \
292 bufferevent_unsuspend_read((b), BEV_SUSPEND_WM)
293
294 /*
295 Disable a bufferevent. Equivalent to bufferevent_disable(), but
296 first resets 'connecting' flag to force EV_WRITE down for sure.
297
298 XXXX this method will go away in the future; try not to add new users.
299 See comment in evhttp_connection_reset() for discussion.
300
301 @param bufev the bufferevent to be disabled
302 @param event any combination of EV_READ | EV_WRITE.
303 @return 0 if successful, or -1 if an error occurred
304 @see bufferevent_disable()
305 */
306 int bufferevent_disable_hard(struct bufferevent *bufev, short event);
307
308 /** Internal: Set up locking on a bufferevent. If lock is set, use it.
309 * Otherwise, use a new lock. */
310 int bufferevent_enable_locking(struct bufferevent *bufev, void *lock);
311 /** Internal: Increment the reference count on bufev. */
312 void bufferevent_incref(struct bufferevent *bufev);
313 /** Internal: Lock bufev and increase its reference count.
314 * unlocking it otherwise. */
315 void _bufferevent_incref_and_lock(struct bufferevent *bufev);
316 /** Internal: Decrement the reference count on bufev. Returns 1 if it freed
317 * the bufferevent.*/
318 int bufferevent_decref(struct bufferevent *bufev);
319 /** Internal: Drop the reference count on bufev, freeing as necessary, and
320 * unlocking it otherwise. Returns 1 if it freed the bufferevent. */
321 int _bufferevent_decref_and_unlock(struct bufferevent *bufev);
322
323 /** Internal: If callbacks are deferred and we have a read callback, schedule
324 * a readcb. Otherwise just run the readcb. */
325 void _bufferevent_run_readcb(struct bufferevent *bufev);
326 /** Internal: If callbacks are deferred and we have a write callback, schedule
327 * a writecb. Otherwise just run the writecb. */
328 void _bufferevent_run_writecb(struct bufferevent *bufev);
329 /** Internal: If callbacks are deferred and we have an eventcb, schedule
330 * it to run with events "what". Otherwise just run the eventcb. */
331 void _bufferevent_run_eventcb(struct bufferevent *bufev, short what);
332
333 /** Internal: Add the event 'ev' with timeout tv, unless tv is set to 0, in
334 * which case add ev with no timeout. */
335 int _bufferevent_add_event(struct event *ev, const struct timeval *tv);
336
337 /* =========
338 * These next functions implement timeouts for bufferevents that aren't doing
339 * anything else with ev_read and ev_write, to handle timeouts.
340 * ========= */
341 /** Internal use: Set up the ev_read and ev_write callbacks so that
342 * the other "generic_timeout" functions will work on it. Call this from
343 * the constructor function. */
344 void _bufferevent_init_generic_timeout_cbs(struct bufferevent *bev);
345 /** Internal use: Delete the ev_read and ev_write callbacks if they're pending.
346 * Call this from the destructor function. */
347 int _bufferevent_del_generic_timeout_cbs(struct bufferevent *bev);
348 /** Internal use: Add or delete the generic timeout events as appropriate.
349 * (If an event is enabled and a timeout is set, we add the event. Otherwise
350 * we delete it.) Call this from anything that changes the timeout values,
351 * that enabled EV_READ or EV_WRITE, or that disables EV_READ or EV_WRITE. */
352 int _bufferevent_generic_adj_timeouts(struct bufferevent *bev);
353
354 /** Internal use: We have just successfully read data into an inbuf, so
355 * reset the read timeout (if any). */
356 #define BEV_RESET_GENERIC_READ_TIMEOUT(bev) \
357 do { \
358 if (evutil_timerisset(&(bev)->timeout_read)) \
359 event_add(&(bev)->ev_read, &(bev)->timeout_read); \
360 } while (0)
361 /** Internal use: We have just successfully written data from an inbuf, so
362 * reset the read timeout (if any). */
363 #define BEV_RESET_GENERIC_WRITE_TIMEOUT(bev) \
364 do { \
365 if (evutil_timerisset(&(bev)->timeout_write)) \
366 event_add(&(bev)->ev_write, &(bev)->timeout_write); \
367 } while (0)
368 #define BEV_DEL_GENERIC_READ_TIMEOUT(bev) \
369 event_del(&(bev)->ev_read)
370 #define BEV_DEL_GENERIC_WRITE_TIMEOUT(bev) \
371 event_del(&(bev)->ev_write)
372
373
374 /** Internal: Given a bufferevent, return its corresponding
375 * bufferevent_private. */
376 #define BEV_UPCAST(b) EVUTIL_UPCAST((b), struct bufferevent_private, bev)
377
378 #ifdef _EVENT_DISABLE_THREAD_SUPPORT
379 #define BEV_LOCK(b) _EVUTIL_NIL_STMT
380 #define BEV_UNLOCK(b) _EVUTIL_NIL_STMT
381 #else
382 /** Internal: Grab the lock (if any) on a bufferevent */
383 #define BEV_LOCK(b) do { \
384 struct bufferevent_private *locking = BEV_UPCAST(b); \
385 EVLOCK_LOCK(locking->lock, 0); \
386 } while (0)
387
388 /** Internal: Release the lock (if any) on a bufferevent */
389 #define BEV_UNLOCK(b) do { \
390 struct bufferevent_private *locking = BEV_UPCAST(b); \
391 EVLOCK_UNLOCK(locking->lock, 0); \
392 } while (0)
393 #endif
394
395
396 /* ==== For rate-limiting. */
397
398 int _bufferevent_decrement_write_buckets(struct bufferevent_private *bev,
399 ev_ssize_t bytes);
400 int _bufferevent_decrement_read_buckets(struct bufferevent_private *bev,
401 ev_ssize_t bytes);
402 ev_ssize_t _bufferevent_get_read_max(struct bufferevent_private *bev);
403 ev_ssize_t _bufferevent_get_write_max(struct bufferevent_private *bev);
404
405 #ifdef __cplusplus
406 }
407 #endif
408
409
410 #endif /* _BUFFEREVENT_INTERNAL_H_ */