/*
* Copyright (c) 2009-2012 Niels Provos, 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.
*/
#include "event2/event-config.h"
#include "evconfig-private.h"
#include <sys/types.h>
#ifdef _WIN32
#include <winsock2.h>
#endif
#include "event2/util.h"
#include "event2/buffer.h"
#include "event2/bufferevent.h"
#include "event2/bufferevent_struct.h"
#include "event2/event.h"
#include "defer-internal.h"
#include "bufferevent-internal.h"
#include "mm-internal.h"
#include "util-internal.h"
struct bufferevent_pair {
struct bufferevent_private bev;
struct bufferevent_pair *partner;
/* For ->destruct() lock checking */
struct bufferevent_pair *unlinked_partner;
};
/* Given a bufferevent that's really a bev part of a bufferevent_pair,
* return that bufferevent_filtered. Returns NULL otherwise.*/
static inline struct bufferevent_pair *
upcast(struct bufferevent *bev)
{
struct bufferevent_pair *bev_p;
bev_p = EVUTIL_UPCAST(bev, struct bufferevent_pair, bev.bev);
EVUTIL_ASSERT(BEV_IS_PAIR(&bev_p->bev.bev));
return bev_p;
}
#define downcast(bev_pair) (&(bev_pair)->bev.bev)
static inline void
incref_and_lock(struct bufferevent *b)
{
struct bufferevent_pair *bevp;
bufferevent_incref_and_lock_(b);
bevp = upcast(b);
if (bevp->partner)
bufferevent_incref_and_lock_(downcast(bevp->partner));
}
static inline void
decref_and_unlock(struct bufferevent *b)
{
struct bufferevent_pair *bevp = upcast(b);
if (bevp->partner)
bufferevent_decref_and_unlock_(downcast(bevp->partner));
bufferevent_decref_and_unlock_(b);
}
/* XXX Handle close */
static void be_pair_outbuf_cb(struct evbuffer *,
const struct evbuffer_cb_info *, void *);
static struct bufferevent_pair *
bufferevent_pair_elt_new(struct event_base *base,
int options)
{
struct bufferevent_pair *bufev;
if (! (bufev = mm_calloc(1, sizeof(struct bufferevent_pair))))
return NULL;
if (bufferevent_init_common_(&bufev->bev, base, &bufferevent_ops_pair,
options)) {
mm_free(bufev);
return NULL;
}
if (!evbuffer_add_cb(bufev->bev.bev.output, be_pair_outbuf_cb, bufev)) {
bufferevent_free(downcast(bufev));
return NULL;
}
bufferevent_init_generic_timeout_cbs_(&bufev->bev.bev);
return bufev;
}
int
bufferevent_pair_new(struct event_base *base, int options,
struct bufferevent *pair[2])
{
struct bufferevent_pair *bufev1 = NULL, *bufev2 = NULL;
int tmp_options;
options |= BEV_OPT_DEFER_CALLBACKS;
tmp_options = options & ~BEV_OPT_THREADSAFE;
bufev1 = bufferevent_pair_elt_new(base, options);
if (!bufev1)
return -1;
bufev2 = bufferevent_pair_elt_new(base, tmp_options);
if (!bufev2) {
bufferevent_free(downcast(bufev1));
return -1;
}
if (options & BEV_OPT_THREADSAFE) {
/*XXXX check return */
bufferevent_enable_locking_(downcast(bufev2), bufev1->bev.lock);
}
bufev1->partner = bufev2;
bufev2->partner = bufev1;
evbuffer_freeze(downcast(bufev1)->input, 0);
evbuffer_freeze(downcast(bufev1)->output, 1);
evbuffer_freeze(downcast(bufev2)->input, 0);
evbuffer_freeze(downcast(bufev2)->output, 1);
pair[0] = downcast(bufev1);
pair[1] = downcast(bufev2);
return 0;
}
static void
be_pair_transfer(struct bufferevent *src, struct bufferevent *dst,
int ignore_wm)
{
size_t dst_size;
size_t n;
evbuffer_unfreeze(src->output, 1);
evbuffer_unfreeze(dst->input, 0);
if (dst->wm_read.high) {
dst_size = evbuffer_get_length(dst->input);
if (dst_size < dst->wm_read.high) {
n = dst->wm_read.high - dst_size;
evbuffer_remove_buffer(src->output, dst->input, n);
} else {
if (!ignore_wm)
goto done;
n = evbuffer_get_length(src->output);
evbuffer_add_buffer(dst->input, src->output);
}
} else {
n = evbuffer_get_length(src->output);
evbuffer_add_buffer(dst->input, src->output);
}
if (n) {
BEV_RESET_GENERIC_READ_TIMEOUT(dst);
if (evbuffer_get_length(dst->output))
BEV_RESET_GENERIC_WRITE_TIMEOUT(dst);
else
BEV_DEL_GENERIC_WRITE_TIMEOUT(dst);
}
bufferevent_trigger_nolock_(dst, EV_READ, 0);
bufferevent_trigger_nolock_(src, EV_WRITE, 0);
done:
evbuffer_freeze(src->output, 1);
evbuffer_freeze(dst->input, 0);
}
static inline int
be_pair_wants_to_talk(struct bufferevent_pair *src,
struct bufferevent_pair *dst)
{
return (downcast(src)->enabled & EV_WRITE) &&
(downcast(dst)->enabled & EV_READ) &&
!dst->bev.read_suspended &&
evbuffer_get_length(downcast(src)->output);
}
static void
be_pair_outbuf_cb(struct evbuffer *outbuf,
const struct evbuffer_cb_info *info, void *arg)
{
struct bufferevent_pair *bev_pair = arg;
struct bufferevent_pair *partner = bev_pair->partner;
incref_and_lock(downcast(bev_pair));
if (info->n_added > info->n_deleted && partner) {
/* We got more data. If the other side's reading, then
hand it over. */
if (be_pair_wants_to_talk(bev_pair, partner)) {
be_pair_transfer(downcast(bev_pair), downcast(partner), 0);
}
}
decref_and_unlock(downcast(bev_pair));
}
static int
be_pair_enable(struct bufferevent *bufev, short events)
{
struct bufferevent_pair *bev_p = upcast(bufev);
struct bufferevent_pair *partner = bev_p->partner;
incref_and_lock(bufev);
if (events & EV_READ) {
BEV_RESET_GENERIC_READ_TIMEOUT(bufev);
}
if ((events & EV_WRITE) && evbuffer_get_length(bufev->output))
BEV_RESET_GENERIC_WRITE_TIMEOUT(bufev);
/* We're starting to read! Does the other side have anything to write?*/
if ((events & EV_READ) && partner &&
be_pair_wants_to_talk(partner, bev_p)) {
be_pair_transfer(downcast(partner), bufev, 0);
}
/* We're starting to write! Does the other side want to read? */
if ((events & EV_WRITE) && partner &&
be_pair_wants_to_talk(bev_p, partner)) {
be_pair_transfer(bufev, downcast(partner), 0);
}
decref_and_unlock(bufev);
return 0;
}
static int
be_pair_disable(struct bufferevent *bev, short events)
{
if (events & EV_READ) {
BEV_DEL_GENERIC_READ_TIMEOUT(bev);
}
if (events & EV_WRITE) {
BEV_DEL_GENERIC_WRITE_TIMEOUT(bev);
}
return 0;
}
static void
be_pair_unlink(struct bufferevent *bev)
{
struct bufferevent_pair *bev_p = upcast(bev);
if (bev_p->partner) {
bev_p->unlinked_partner = bev_p->partner;
bev_p->partner->partner = NULL;
bev_p->partner = NULL;
}
}
/* Free *shared* lock in the latest be (since we share it between two of them). */
static void
be_pair_destruct(struct bufferevent *bev)
{
struct bufferevent_pair *bev_p = upcast(bev);
/* Transfer ownership of the lock into partner, otherwise we will use
* already free'd lock during freeing second bev, see next example:
*
* bev1->own_lock = 1
* bev2->own_lock = 0
* bev2->lock = bev1->lock
*
* bufferevent_free(bev1) # refcnt == 0 -> unlink
* bufferevent_free(bev2) # refcnt == 0 -> unlink
*
* event_base_free() -> finalizers -> EVTHREAD_FREE_LOCK(bev1->lock)
* -> BEV_LOCK(bev2->lock) <-- already freed
*
* Where bev1 == pair[0], bev2 == pair[1].
*/
if (bev_p->unlinked_partner && bev_p->bev.own_lock) {
bev_p->unlinked_partner->bev.own_lock = 1;
bev_p->bev.own_lock = 0;
}
bev_p->unlinked_partner = NULL;
}
static int
be_pair_flush(struct bufferevent *bev, short iotype,
enum bufferevent_flush_mode mode)
{
struct bufferevent_pair *bev_p = upcast(bev);
struct bufferevent *partner;
if (!bev_p->partner)
return -1;
if (mode == BEV_NORMAL)
return 0;
incref_and_lock(bev);
partner = downcast(bev_p->partner);
if ((iotype & EV_READ) != 0)
be_pair_transfer(partner, bev, 1);
if ((iotype & EV_WRITE) != 0)
be_pair_transfer(bev, partner, 1);
if (mode == BEV_FINISHED) {
short what = BEV_EVENT_EOF;
if (iotype & EV_READ)
what |= BEV_EVENT_WRITING;
if (iotype & EV_WRITE)
what |= BEV_EVENT_READING;
bufferevent_run_eventcb_(partner, what, 0);
}
decref_and_unlock(bev);
return 0;
}
struct bufferevent *
bufferevent_pair_get_partner(struct bufferevent *bev)
{
struct bufferevent_pair *bev_p;
struct bufferevent *partner = NULL;
if (!BEV_IS_PAIR(bev))
return NULL;
bev_p = upcast(bev);
incref_and_lock(bev);
if (bev_p->partner)
partner = downcast(bev_p->partner);
decref_and_unlock(bev);
return partner;
}
const struct bufferevent_ops bufferevent_ops_pair = {
"pair_elt",
evutil_offsetof(struct bufferevent_pair, bev.bev),
be_pair_enable,
be_pair_disable,
be_pair_unlink,
be_pair_destruct,
bufferevent_generic_adj_timeouts_,
be_pair_flush,
NULL, /* ctrl */
};
