michael@0: /*
michael@0:  * Copyright (c) 2009-2012 Niels Provos, Nick Mathewson
michael@0:  *
michael@0:  * Redistribution and use in source and binary forms, with or without
michael@0:  * modification, are permitted provided that the following conditions
michael@0:  * are met:
michael@0:  * 1. Redistributions of source code must retain the above copyright
michael@0:  *    notice, this list of conditions and the following disclaimer.
michael@0:  * 2. Redistributions in binary form must reproduce the above copyright
michael@0:  *    notice, this list of conditions and the following disclaimer in the
michael@0:  *    documentation and/or other materials provided with the distribution.
michael@0:  * 3. The name of the author may not be used to endorse or promote products
michael@0:  *    derived from this software without specific prior written permission.
michael@0:  *
michael@0:  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
michael@0:  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
michael@0:  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
michael@0:  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
michael@0:  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
michael@0:  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
michael@0:  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
michael@0:  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
michael@0:  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
michael@0:  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
michael@0:  */
michael@0: 
michael@0: #include <sys/types.h>
michael@0: 
michael@0: #ifdef WIN32
michael@0: #include <winsock2.h>
michael@0: #endif
michael@0: 
michael@0: #include "event2/event-config.h"
michael@0: 
michael@0: #include "event2/util.h"
michael@0: #include "event2/buffer.h"
michael@0: #include "event2/bufferevent.h"
michael@0: #include "event2/bufferevent_struct.h"
michael@0: #include "event2/event.h"
michael@0: #include "defer-internal.h"
michael@0: #include "bufferevent-internal.h"
michael@0: #include "mm-internal.h"
michael@0: #include "util-internal.h"
michael@0: 
michael@0: struct bufferevent_pair {
michael@0: 	struct bufferevent_private bev;
michael@0: 	struct bufferevent_pair *partner;
michael@0: };
michael@0: 
michael@0: 
michael@0: /* Given a bufferevent that's really a bev part of a bufferevent_pair,
michael@0:  * return that bufferevent_filtered. Returns NULL otherwise.*/
michael@0: static inline struct bufferevent_pair *
michael@0: upcast(struct bufferevent *bev)
michael@0: {
michael@0: 	struct bufferevent_pair *bev_p;
michael@0: 	if (bev->be_ops != &bufferevent_ops_pair)
michael@0: 		return NULL;
michael@0: 	bev_p = EVUTIL_UPCAST(bev, struct bufferevent_pair, bev.bev);
michael@0: 	EVUTIL_ASSERT(bev_p->bev.bev.be_ops == &bufferevent_ops_pair);
michael@0: 	return bev_p;
michael@0: }
michael@0: 
michael@0: #define downcast(bev_pair) (&(bev_pair)->bev.bev)
michael@0: 
michael@0: static inline void
michael@0: incref_and_lock(struct bufferevent *b)
michael@0: {
michael@0: 	struct bufferevent_pair *bevp;
michael@0: 	_bufferevent_incref_and_lock(b);
michael@0: 	bevp = upcast(b);
michael@0: 	if (bevp->partner)
michael@0: 		_bufferevent_incref_and_lock(downcast(bevp->partner));
michael@0: }
michael@0: 
michael@0: static inline void
michael@0: decref_and_unlock(struct bufferevent *b)
michael@0: {
michael@0: 	struct bufferevent_pair *bevp = upcast(b);
michael@0: 	if (bevp->partner)
michael@0: 		_bufferevent_decref_and_unlock(downcast(bevp->partner));
michael@0: 	_bufferevent_decref_and_unlock(b);
michael@0: }
michael@0: 
michael@0: /* XXX Handle close */
michael@0: 
michael@0: static void be_pair_outbuf_cb(struct evbuffer *,
michael@0:     const struct evbuffer_cb_info *, void *);
michael@0: 
michael@0: static struct bufferevent_pair *
michael@0: bufferevent_pair_elt_new(struct event_base *base,
michael@0:     int options)
michael@0: {
michael@0: 	struct bufferevent_pair *bufev;
michael@0: 	if (! (bufev = mm_calloc(1, sizeof(struct bufferevent_pair))))
michael@0: 		return NULL;
michael@0: 	if (bufferevent_init_common(&bufev->bev, base, &bufferevent_ops_pair,
michael@0: 		options)) {
michael@0: 		mm_free(bufev);
michael@0: 		return NULL;
michael@0: 	}
michael@0: 	if (!evbuffer_add_cb(bufev->bev.bev.output, be_pair_outbuf_cb, bufev)) {
michael@0: 		bufferevent_free(downcast(bufev));
michael@0: 		return NULL;
michael@0: 	}
michael@0: 
michael@0: 	_bufferevent_init_generic_timeout_cbs(&bufev->bev.bev);
michael@0: 
michael@0: 	return bufev;
michael@0: }
michael@0: 
michael@0: int
michael@0: bufferevent_pair_new(struct event_base *base, int options,
michael@0:     struct bufferevent *pair[2])
michael@0: {
michael@0: 	struct bufferevent_pair *bufev1 = NULL, *bufev2 = NULL;
michael@0: 	int tmp_options;
michael@0: 
michael@0: 	options |= BEV_OPT_DEFER_CALLBACKS;
michael@0: 	tmp_options = options & ~BEV_OPT_THREADSAFE;
michael@0: 
michael@0: 	bufev1 = bufferevent_pair_elt_new(base, options);
michael@0: 	if (!bufev1)
michael@0: 		return -1;
michael@0: 	bufev2 = bufferevent_pair_elt_new(base, tmp_options);
michael@0: 	if (!bufev2) {
michael@0: 		bufferevent_free(downcast(bufev1));
michael@0: 		return -1;
michael@0: 	}
michael@0: 
michael@0: 	if (options & BEV_OPT_THREADSAFE) {
michael@0: 		/*XXXX check return */
michael@0: 		bufferevent_enable_locking(downcast(bufev2), bufev1->bev.lock);
michael@0: 	}
michael@0: 
michael@0: 	bufev1->partner = bufev2;
michael@0: 	bufev2->partner = bufev1;
michael@0: 
michael@0: 	evbuffer_freeze(downcast(bufev1)->input, 0);
michael@0: 	evbuffer_freeze(downcast(bufev1)->output, 1);
michael@0: 	evbuffer_freeze(downcast(bufev2)->input, 0);
michael@0: 	evbuffer_freeze(downcast(bufev2)->output, 1);
michael@0: 
michael@0: 	pair[0] = downcast(bufev1);
michael@0: 	pair[1] = downcast(bufev2);
michael@0: 
michael@0: 	return 0;
michael@0: }
michael@0: 
michael@0: static void
michael@0: be_pair_transfer(struct bufferevent *src, struct bufferevent *dst,
michael@0:     int ignore_wm)
michael@0: {
michael@0: 	size_t src_size, dst_size;
michael@0: 	size_t n;
michael@0: 
michael@0: 	evbuffer_unfreeze(src->output, 1);
michael@0: 	evbuffer_unfreeze(dst->input, 0);
michael@0: 
michael@0: 	if (dst->wm_read.high) {
michael@0: 		dst_size = evbuffer_get_length(dst->input);
michael@0: 		if (dst_size < dst->wm_read.high) {
michael@0: 			n = dst->wm_read.high - dst_size;
michael@0: 			evbuffer_remove_buffer(src->output, dst->input, n);
michael@0: 		} else {
michael@0: 			if (!ignore_wm)
michael@0: 				goto done;
michael@0: 			n = evbuffer_get_length(src->output);
michael@0: 			evbuffer_add_buffer(dst->input, src->output);
michael@0: 		}
michael@0: 	} else {
michael@0: 		n = evbuffer_get_length(src->output);
michael@0: 		evbuffer_add_buffer(dst->input, src->output);
michael@0: 	}
michael@0: 
michael@0: 	if (n) {
michael@0: 		BEV_RESET_GENERIC_READ_TIMEOUT(dst);
michael@0: 
michael@0: 		if (evbuffer_get_length(dst->output))
michael@0: 			BEV_RESET_GENERIC_WRITE_TIMEOUT(dst);
michael@0: 		else
michael@0: 			BEV_DEL_GENERIC_WRITE_TIMEOUT(dst);
michael@0: 	}
michael@0: 
michael@0: 	src_size = evbuffer_get_length(src->output);
michael@0: 	dst_size = evbuffer_get_length(dst->input);
michael@0: 
michael@0: 	if (dst_size >= dst->wm_read.low) {
michael@0: 		_bufferevent_run_readcb(dst);
michael@0: 	}
michael@0: 	if (src_size <= src->wm_write.low) {
michael@0: 		_bufferevent_run_writecb(src);
michael@0: 	}
michael@0: done:
michael@0: 	evbuffer_freeze(src->output, 1);
michael@0: 	evbuffer_freeze(dst->input, 0);
michael@0: }
michael@0: 
michael@0: static inline int
michael@0: be_pair_wants_to_talk(struct bufferevent_pair *src,
michael@0:     struct bufferevent_pair *dst)
michael@0: {
michael@0: 	return (downcast(src)->enabled & EV_WRITE) &&
michael@0: 	    (downcast(dst)->enabled & EV_READ) &&
michael@0: 	    !dst->bev.read_suspended &&
michael@0: 	    evbuffer_get_length(downcast(src)->output);
michael@0: }
michael@0: 
michael@0: static void
michael@0: be_pair_outbuf_cb(struct evbuffer *outbuf,
michael@0:     const struct evbuffer_cb_info *info, void *arg)
michael@0: {
michael@0: 	struct bufferevent_pair *bev_pair = arg;
michael@0: 	struct bufferevent_pair *partner = bev_pair->partner;
michael@0: 
michael@0: 	incref_and_lock(downcast(bev_pair));
michael@0: 
michael@0: 	if (info->n_added > info->n_deleted && partner) {
michael@0: 		/* We got more data.  If the other side's reading, then
michael@0: 		   hand it over. */
michael@0: 		if (be_pair_wants_to_talk(bev_pair, partner)) {
michael@0: 			be_pair_transfer(downcast(bev_pair), downcast(partner), 0);
michael@0: 		}
michael@0: 	}
michael@0: 
michael@0: 	decref_and_unlock(downcast(bev_pair));
michael@0: }
michael@0: 
michael@0: static int
michael@0: be_pair_enable(struct bufferevent *bufev, short events)
michael@0: {
michael@0: 	struct bufferevent_pair *bev_p = upcast(bufev);
michael@0: 	struct bufferevent_pair *partner = bev_p->partner;
michael@0: 
michael@0: 	incref_and_lock(bufev);
michael@0: 
michael@0: 	if (events & EV_READ) {
michael@0: 		BEV_RESET_GENERIC_READ_TIMEOUT(bufev);
michael@0: 	}
michael@0: 	if ((events & EV_WRITE) && evbuffer_get_length(bufev->output))
michael@0: 		BEV_RESET_GENERIC_WRITE_TIMEOUT(bufev);
michael@0: 
michael@0: 	/* We're starting to read! Does the other side have anything to write?*/
michael@0: 	if ((events & EV_READ) && partner &&
michael@0: 	    be_pair_wants_to_talk(partner, bev_p)) {
michael@0: 		be_pair_transfer(downcast(partner), bufev, 0);
michael@0: 	}
michael@0: 	/* We're starting to write! Does the other side want to read? */
michael@0: 	if ((events & EV_WRITE) && partner &&
michael@0: 	    be_pair_wants_to_talk(bev_p, partner)) {
michael@0: 		be_pair_transfer(bufev, downcast(partner), 0);
michael@0: 	}
michael@0: 	decref_and_unlock(bufev);
michael@0: 	return 0;
michael@0: }
michael@0: 
michael@0: static int
michael@0: be_pair_disable(struct bufferevent *bev, short events)
michael@0: {
michael@0: 	if (events & EV_READ) {
michael@0: 		BEV_DEL_GENERIC_READ_TIMEOUT(bev);
michael@0: 	}
michael@0: 	if (events & EV_WRITE)
michael@0: 		BEV_DEL_GENERIC_WRITE_TIMEOUT(bev);
michael@0: 	return 0;
michael@0: }
michael@0: 
michael@0: static void
michael@0: be_pair_destruct(struct bufferevent *bev)
michael@0: {
michael@0: 	struct bufferevent_pair *bev_p = upcast(bev);
michael@0: 
michael@0: 	if (bev_p->partner) {
michael@0: 		bev_p->partner->partner = NULL;
michael@0: 		bev_p->partner = NULL;
michael@0: 	}
michael@0: 
michael@0: 	_bufferevent_del_generic_timeout_cbs(bev);
michael@0: }
michael@0: 
michael@0: static int
michael@0: be_pair_flush(struct bufferevent *bev, short iotype,
michael@0:     enum bufferevent_flush_mode mode)
michael@0: {
michael@0: 	struct bufferevent_pair *bev_p = upcast(bev);
michael@0: 	struct bufferevent *partner;
michael@0: 	incref_and_lock(bev);
michael@0: 	if (!bev_p->partner)
michael@0: 		return -1;
michael@0: 
michael@0: 	partner = downcast(bev_p->partner);
michael@0: 
michael@0: 	if (mode == BEV_NORMAL)
michael@0: 		return 0;
michael@0: 
michael@0: 	if ((iotype & EV_READ) != 0)
michael@0: 		be_pair_transfer(partner, bev, 1);
michael@0: 
michael@0: 	if ((iotype & EV_WRITE) != 0)
michael@0: 		be_pair_transfer(bev, partner, 1);
michael@0: 
michael@0: 	if (mode == BEV_FINISHED) {
michael@0: 		_bufferevent_run_eventcb(partner, iotype|BEV_EVENT_EOF);
michael@0: 	}
michael@0: 	decref_and_unlock(bev);
michael@0: 	return 0;
michael@0: }
michael@0: 
michael@0: struct bufferevent *
michael@0: bufferevent_pair_get_partner(struct bufferevent *bev)
michael@0: {
michael@0: 	struct bufferevent_pair *bev_p;
michael@0: 	struct bufferevent *partner;
michael@0: 	bev_p = upcast(bev);
michael@0: 	if (! bev_p)
michael@0: 		return NULL;
michael@0: 
michael@0: 	incref_and_lock(bev);
michael@0: 	partner = downcast(bev_p->partner);
michael@0: 	decref_and_unlock(bev);
michael@0: 	return partner;
michael@0: }
michael@0: 
michael@0: const struct bufferevent_ops bufferevent_ops_pair = {
michael@0: 	"pair_elt",
michael@0: 	evutil_offsetof(struct bufferevent_pair, bev.bev),
michael@0: 	be_pair_enable,
michael@0: 	be_pair_disable,
michael@0: 	be_pair_destruct,
michael@0: 	_bufferevent_generic_adj_timeouts,
michael@0: 	be_pair_flush,
michael@0: 	NULL, /* ctrl */
michael@0: };