/*

 * Copyright (c) 2008-2012 Niels Provos and Nick Mathewson

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in the

 *    documentation and/or other materials provided with the distribution.

 * 3. The name of the author may not be used to endorse or promote products

 *    derived from this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR

 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES

 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.

 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,

 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT

 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF

 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

#ifndef _BUFFEREVENT_INTERNAL_H_

#define _BUFFEREVENT_INTERNAL_H_

#ifdef __cplusplus

extern "C" {

#endif

#include "event2/event-config.h"

#include "event2/util.h"

#include "defer-internal.h"

#include "evthread-internal.h"

#include "event2/thread.h"

#include "ratelim-internal.h"

#include "event2/bufferevent_struct.h"

/* These flags are reasons that we might be declining to actually enable

   reading or writing on a bufferevent.

 */

/* On a all bufferevents, for reading: used when we have read up to the

   watermark value.

   On a filtering bufferevent, for writing: used when the underlying

   bufferevent's write buffer has been filled up to its watermark

   value.

*/

#define BEV_SUSPEND_WM 0x01

/* On a base bufferevent: when we have emptied a bandwidth buckets */

#define BEV_SUSPEND_BW 0x02

/* On a base bufferevent: when we have emptied the group's bandwidth bucket. */

#define BEV_SUSPEND_BW_GROUP 0x04

/* On a socket bufferevent: can't do any operations while we're waiting for

 * name lookup to finish. */

#define BEV_SUSPEND_LOOKUP 0x08

/* On a base bufferevent, for reading: used when a filter has choked this

 * (underlying) bufferevent because it has stopped reading from it. */

#define BEV_SUSPEND_FILT_READ 0x10

typedef ev_uint16_t bufferevent_suspend_flags;

struct bufferevent_rate_limit_group {

	/** List of all members in the group */

	TAILQ_HEAD(rlim_group_member_list, bufferevent_private) members;

	/** Current limits for the group. */

	struct ev_token_bucket rate_limit;

	struct ev_token_bucket_cfg rate_limit_cfg;

	/** True iff we don't want to read from any member of the group.until

	 * the token bucket refills.  */

	unsigned read_suspended : 1;

	/** True iff we don't want to write from any member of the group.until

	 * the token bucket refills.  */

	unsigned write_suspended : 1;

	/** True iff we were unable to suspend one of the bufferevents in the

	 * group for reading the last time we tried, and we should try

	 * again. */

	unsigned pending_unsuspend_read : 1;

	/** True iff we were unable to suspend one of the bufferevents in the

	 * group for writing the last time we tried, and we should try

	 * again. */

	unsigned pending_unsuspend_write : 1;

	/*@{*/

	/** Total number of bytes read or written in this group since last

	 * reset. */

	ev_uint64_t total_read;

	ev_uint64_t total_written;

	/*@}*/

	/** The number of bufferevents in the group. */

	int n_members;

	/** The smallest number of bytes that any member of the group should

	 * be limited to read or write at a time. */

	ev_ssize_t min_share;

	ev_ssize_t configured_min_share;

	/** Timeout event that goes off once a tick, when the bucket is ready

	 * to refill. */

	struct event master_refill_event;

	/** Lock to protect the members of this group.  This lock should nest

	 * within every bufferevent lock: if you are holding this lock, do

	 * not assume you can lock another bufferevent. */

	void *lock;

};

/** Fields for rate-limiting a single bufferevent. */

struct bufferevent_rate_limit {

	/* Linked-list elements for storing this bufferevent_private in a

	 * group.

	 *

	 * Note that this field is supposed to be protected by the group

	 * lock */

	TAILQ_ENTRY(bufferevent_private) next_in_group;

	/** The rate-limiting group for this bufferevent, or NULL if it is

	 * only rate-limited on its own. */

	struct bufferevent_rate_limit_group *group;

	/* This bufferevent's current limits. */

	struct ev_token_bucket limit;

	/* Pointer to the rate-limit configuration for this bufferevent.

	 * Can be shared.  XXX reference-count this? */

	struct ev_token_bucket_cfg *cfg;

	/* Timeout event used when one this bufferevent's buckets are

	 * empty. */

	struct event refill_bucket_event;

};

/** Parts of the bufferevent structure that are shared among all bufferevent

 * types, but not exposed in bufferevent_struct.h. */

struct bufferevent_private {

	/** The underlying bufferevent structure. */

	struct bufferevent bev;

	/** Evbuffer callback to enforce watermarks on input. */

	struct evbuffer_cb_entry *read_watermarks_cb;

	/** If set, we should free the lock when we free the bufferevent. */

	unsigned own_lock : 1;

	/** Flag: set if we have deferred callbacks and a read callback is

	 * pending. */

	unsigned readcb_pending : 1;

	/** Flag: set if we have deferred callbacks and a write callback is

	 * pending. */

	unsigned writecb_pending : 1;

	/** Flag: set if we are currently busy connecting. */

	unsigned connecting : 1;

	/** Flag: set if a connect failed prematurely; this is a hack for

	 * getting around the bufferevent abstraction. */

	unsigned connection_refused : 1;

	/** Set to the events pending if we have deferred callbacks and

	 * an events callback is pending. */

	short eventcb_pending;

	/** If set, read is suspended until one or more conditions are over.

	 * The actual value here is a bitfield of those conditions; see the

	 * BEV_SUSPEND_* flags above. */

	bufferevent_suspend_flags read_suspended;

	/** If set, writing is suspended until one or more conditions are over.

	 * The actual value here is a bitfield of those conditions; see the

	 * BEV_SUSPEND_* flags above. */

	bufferevent_suspend_flags write_suspended;

	/** Set to the current socket errno if we have deferred callbacks and

	 * an events callback is pending. */

	int errno_pending;

	/** The DNS error code for bufferevent_socket_connect_hostname */

	int dns_error;

	/** Used to implement deferred callbacks */

	struct deferred_cb deferred;

	/** The options this bufferevent was constructed with */

	enum bufferevent_options options;

	/** Current reference count for this bufferevent. */

	int refcnt;

	/** Lock for this bufferevent.  Shared by the inbuf and the outbuf.

	 * If NULL, locking is disabled. */

	void *lock;

	/** Rate-limiting information for this bufferevent */

	struct bufferevent_rate_limit *rate_limiting;

};

/** Possible operations for a control callback. */

enum bufferevent_ctrl_op {

	BEV_CTRL_SET_FD,

	BEV_CTRL_GET_FD,

	BEV_CTRL_GET_UNDERLYING,

	BEV_CTRL_CANCEL_ALL

};

/** Possible data types for a control callback */

union bufferevent_ctrl_data {

	void *ptr;

	evutil_socket_t fd;

};

/**

   Implementation table for a bufferevent: holds function pointers and other

   information to make the various bufferevent types work.

*/

struct bufferevent_ops {

	/** The name of the bufferevent's type. */

	const char *type;

	/** At what offset into the implementation type will we find a

	    bufferevent structure?

	    Example: if the type is implemented as

	    struct bufferevent_x {

	       int extra_data;

	       struct bufferevent bev;

	    }

	    then mem_offset should be offsetof(struct bufferevent_x, bev)

	*/

	off_t mem_offset;

	/** Enables one or more of EV_READ|EV_WRITE on a bufferevent.  Does

	    not need to adjust the 'enabled' field.  Returns 0 on success, -1

	    on failure.

	 */

	int (*enable)(struct bufferevent *, short);

	/** Disables one or more of EV_READ|EV_WRITE on a bufferevent.  Does

	    not need to adjust the 'enabled' field.  Returns 0 on success, -1

	    on failure.

	 */

	int (*disable)(struct bufferevent *, short);

	/** Free any storage and deallocate any extra data or structures used

	    in this implementation.

	 */

	void (*destruct)(struct bufferevent *);

	/** Called when the timeouts on the bufferevent have changed.*/

	int (*adj_timeouts)(struct bufferevent *);

	/** Called to flush data. */

	int (*flush)(struct bufferevent *, short, enum bufferevent_flush_mode);

	/** Called to access miscellaneous fields. */

	int (*ctrl)(struct bufferevent *, enum bufferevent_ctrl_op, union bufferevent_ctrl_data *);

};

extern const struct bufferevent_ops bufferevent_ops_socket;

extern const struct bufferevent_ops bufferevent_ops_filter;

extern const struct bufferevent_ops bufferevent_ops_pair;

#define BEV_IS_SOCKET(bevp) ((bevp)->be_ops == &bufferevent_ops_socket)

#define BEV_IS_FILTER(bevp) ((bevp)->be_ops == &bufferevent_ops_filter)

#define BEV_IS_PAIR(bevp) ((bevp)->be_ops == &bufferevent_ops_pair)

#ifdef WIN32

extern const struct bufferevent_ops bufferevent_ops_async;

#define BEV_IS_ASYNC(bevp) ((bevp)->be_ops == &bufferevent_ops_async)

#else

#define BEV_IS_ASYNC(bevp) 0

#endif

/** Initialize the shared parts of a bufferevent. */

int bufferevent_init_common(struct bufferevent_private *, struct event_base *, const struct bufferevent_ops *, enum bufferevent_options options);

/** For internal use: temporarily stop all reads on bufev, until the conditions

 * in 'what' are over. */

void bufferevent_suspend_read(struct bufferevent *bufev, bufferevent_suspend_flags what);

/** For internal use: clear the conditions 'what' on bufev, and re-enable

 * reading if there are no conditions left. */

void bufferevent_unsuspend_read(struct bufferevent *bufev, bufferevent_suspend_flags what);

/** For internal use: temporarily stop all writes on bufev, until the conditions

 * in 'what' are over. */

void bufferevent_suspend_write(struct bufferevent *bufev, bufferevent_suspend_flags what);

/** For internal use: clear the conditions 'what' on bufev, and re-enable

 * writing if there are no conditions left. */

void bufferevent_unsuspend_write(struct bufferevent *bufev, bufferevent_suspend_flags what);

#define bufferevent_wm_suspend_read(b) \

	bufferevent_suspend_read((b), BEV_SUSPEND_WM)

#define bufferevent_wm_unsuspend_read(b) \

	bufferevent_unsuspend_read((b), BEV_SUSPEND_WM)

/*

  Disable a bufferevent.  Equivalent to bufferevent_disable(), but

  first resets 'connecting' flag to force EV_WRITE down for sure.

  XXXX this method will go away in the future; try not to add new users.

    See comment in evhttp_connection_reset() for discussion.

  @param bufev the bufferevent to be disabled

  @param event any combination of EV_READ | EV_WRITE.

  @return 0 if successful, or -1 if an error occurred

  @see bufferevent_disable()

 */

int bufferevent_disable_hard(struct bufferevent *bufev, short event);

/** Internal: Set up locking on a bufferevent.  If lock is set, use it.

 * Otherwise, use a new lock. */

int bufferevent_enable_locking(struct bufferevent *bufev, void *lock);

/** Internal: Increment the reference count on bufev. */

void bufferevent_incref(struct bufferevent *bufev);

/** Internal: Lock bufev and increase its reference count.

 * unlocking it otherwise. */

void _bufferevent_incref_and_lock(struct bufferevent *bufev);

/** Internal: Decrement the reference count on bufev.  Returns 1 if it freed

 * the bufferevent.*/

int bufferevent_decref(struct bufferevent *bufev);

/** Internal: Drop the reference count on bufev, freeing as necessary, and

 * unlocking it otherwise.  Returns 1 if it freed the bufferevent. */

int _bufferevent_decref_and_unlock(struct bufferevent *bufev);

/** Internal: If callbacks are deferred and we have a read callback, schedule

 * a readcb.  Otherwise just run the readcb. */

void _bufferevent_run_readcb(struct bufferevent *bufev);

/** Internal: If callbacks are deferred and we have a write callback, schedule

 * a writecb.  Otherwise just run the writecb. */

void _bufferevent_run_writecb(struct bufferevent *bufev);

/** Internal: If callbacks are deferred and we have an eventcb, schedule

 * it to run with events "what".  Otherwise just run the eventcb. */

void _bufferevent_run_eventcb(struct bufferevent *bufev, short what);

/** Internal: Add the event 'ev' with timeout tv, unless tv is set to 0, in

 * which case add ev with no timeout. */

int _bufferevent_add_event(struct event *ev, const struct timeval *tv);

/* =========

 * These next functions implement timeouts for bufferevents that aren't doing

 * anything else with ev_read and ev_write, to handle timeouts.

 * ========= */

/** Internal use: Set up the ev_read and ev_write callbacks so that

 * the other "generic_timeout" functions will work on it.  Call this from

 * the constructor function. */

void _bufferevent_init_generic_timeout_cbs(struct bufferevent *bev);

/** Internal use: Delete the ev_read and ev_write callbacks if they're pending.

 * Call this from the destructor function. */

int _bufferevent_del_generic_timeout_cbs(struct bufferevent *bev);

/** Internal use: Add or delete the generic timeout events as appropriate.

 * (If an event is enabled and a timeout is set, we add the event.  Otherwise

 * we delete it.)  Call this from anything that changes the timeout values,

 * that enabled EV_READ or EV_WRITE, or that disables EV_READ or EV_WRITE. */

int _bufferevent_generic_adj_timeouts(struct bufferevent *bev);

/** Internal use: We have just successfully read data into an inbuf, so

 * reset the read timeout (if any). */

#define BEV_RESET_GENERIC_READ_TIMEOUT(bev)				\

	do {								\

		if (evutil_timerisset(&(bev)->timeout_read))		\

			event_add(&(bev)->ev_read, &(bev)->timeout_read); \

	} while (0)

/** Internal use: We have just successfully written data from an inbuf, so

 * reset the read timeout (if any). */

#define BEV_RESET_GENERIC_WRITE_TIMEOUT(bev)				\

	do {								\

		if (evutil_timerisset(&(bev)->timeout_write))		\

			event_add(&(bev)->ev_write, &(bev)->timeout_write); \

	} while (0)

#define BEV_DEL_GENERIC_READ_TIMEOUT(bev)	\

		event_del(&(bev)->ev_read)

#define BEV_DEL_GENERIC_WRITE_TIMEOUT(bev)	\

		event_del(&(bev)->ev_write)

/** Internal: Given a bufferevent, return its corresponding

 * bufferevent_private. */

#define BEV_UPCAST(b) EVUTIL_UPCAST((b), struct bufferevent_private, bev)

#ifdef _EVENT_DISABLE_THREAD_SUPPORT

#define BEV_LOCK(b) _EVUTIL_NIL_STMT

#define BEV_UNLOCK(b) _EVUTIL_NIL_STMT

#else

/** Internal: Grab the lock (if any) on a bufferevent */

#define BEV_LOCK(b) do {						\

		struct bufferevent_private *locking =  BEV_UPCAST(b);	\

		EVLOCK_LOCK(locking->lock, 0);				\

	} while (0)

/** Internal: Release the lock (if any) on a bufferevent */

#define BEV_UNLOCK(b) do {						\

		struct bufferevent_private *locking =  BEV_UPCAST(b);	\

		EVLOCK_UNLOCK(locking->lock, 0);			\

	} while (0)

#endif

/* ==== For rate-limiting. */

int _bufferevent_decrement_write_buckets(struct bufferevent_private *bev,

    ev_ssize_t bytes);

int _bufferevent_decrement_read_buckets(struct bufferevent_private *bev,

    ev_ssize_t bytes);

ev_ssize_t _bufferevent_get_read_max(struct bufferevent_private *bev);

ev_ssize_t _bufferevent_get_write_max(struct bufferevent_private *bev);

#ifdef __cplusplus

}

#endif

#endif /* _BUFFEREVENT_INTERNAL_H_ */