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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_ */
411