1 /*
2 * Copyright (c) 2009-2012 Niels Provos, 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
27 #include <sys/types.h>
28
29 #ifdef WIN32
30 #include <winsock2.h>
31 #endif
32
33 #include "event2/event-config.h"
34
35 #include "event2/util.h"
36 #include "event2/buffer.h"
37 #include "event2/bufferevent.h"
38 #include "event2/bufferevent_struct.h"
39 #include "event2/event.h"
40 #include "defer-internal.h"
41 #include "bufferevent-internal.h"
42 #include "mm-internal.h"
43 #include "util-internal.h"
44
45 struct bufferevent_pair {
46 struct bufferevent_private bev;
47 struct bufferevent_pair *partner;
48 };
49
50
51 /* Given a bufferevent that's really a bev part of a bufferevent_pair,
52 * return that bufferevent_filtered. Returns NULL otherwise.*/
53 static inline struct bufferevent_pair *
upcast(struct bufferevent * bev)54 upcast(struct bufferevent *bev)
55 {
56 struct bufferevent_pair *bev_p;
57 if (bev->be_ops != &bufferevent_ops_pair)
58 return NULL;
59 bev_p = EVUTIL_UPCAST(bev, struct bufferevent_pair, bev.bev);
60 EVUTIL_ASSERT(bev_p->bev.bev.be_ops == &bufferevent_ops_pair);
61 return bev_p;
62 }
63
64 #define downcast(bev_pair) (&(bev_pair)->bev.bev)
65
66 static inline void
incref_and_lock(struct bufferevent * b)67 incref_and_lock(struct bufferevent *b)
68 {
69 struct bufferevent_pair *bevp;
70 _bufferevent_incref_and_lock(b);
71 bevp = upcast(b);
72 if (bevp->partner)
73 _bufferevent_incref_and_lock(downcast(bevp->partner));
74 }
75
76 static inline void
decref_and_unlock(struct bufferevent * b)77 decref_and_unlock(struct bufferevent *b)
78 {
79 struct bufferevent_pair *bevp = upcast(b);
80 if (bevp->partner)
81 _bufferevent_decref_and_unlock(downcast(bevp->partner));
82 _bufferevent_decref_and_unlock(b);
83 }
84
85 /* XXX Handle close */
86
87 static void be_pair_outbuf_cb(struct evbuffer *,
88 const struct evbuffer_cb_info *, void *);
89
90 static struct bufferevent_pair *
bufferevent_pair_elt_new(struct event_base * base,int options)91 bufferevent_pair_elt_new(struct event_base *base,
92 int options)
93 {
94 struct bufferevent_pair *bufev;
95 if (! (bufev = mm_calloc(1, sizeof(struct bufferevent_pair))))
96 return NULL;
97 if (bufferevent_init_common(&bufev->bev, base, &bufferevent_ops_pair,
98 options)) {
99 mm_free(bufev);
100 return NULL;
101 }
102 if (!evbuffer_add_cb(bufev->bev.bev.output, be_pair_outbuf_cb, bufev)) {
103 bufferevent_free(downcast(bufev));
104 return NULL;
105 }
106
107 _bufferevent_init_generic_timeout_cbs(&bufev->bev.bev);
108
109 return bufev;
110 }
111
112 int
bufferevent_pair_new(struct event_base * base,int options,struct bufferevent * pair[2])113 bufferevent_pair_new(struct event_base *base, int options,
114 struct bufferevent *pair[2])
115 {
116 struct bufferevent_pair *bufev1 = NULL, *bufev2 = NULL;
117 int tmp_options;
118
119 options |= BEV_OPT_DEFER_CALLBACKS;
120 tmp_options = options & ~BEV_OPT_THREADSAFE;
121
122 bufev1 = bufferevent_pair_elt_new(base, options);
123 if (!bufev1)
124 return -1;
125 bufev2 = bufferevent_pair_elt_new(base, tmp_options);
126 if (!bufev2) {
127 bufferevent_free(downcast(bufev1));
128 return -1;
129 }
130
131 if (options & BEV_OPT_THREADSAFE) {
132 /*XXXX check return */
133 bufferevent_enable_locking(downcast(bufev2), bufev1->bev.lock);
134 }
135
136 bufev1->partner = bufev2;
137 bufev2->partner = bufev1;
138
139 evbuffer_freeze(downcast(bufev1)->input, 0);
140 evbuffer_freeze(downcast(bufev1)->output, 1);
141 evbuffer_freeze(downcast(bufev2)->input, 0);
142 evbuffer_freeze(downcast(bufev2)->output, 1);
143
144 pair[0] = downcast(bufev1);
145 pair[1] = downcast(bufev2);
146
147 return 0;
148 }
149
150 static void
be_pair_transfer(struct bufferevent * src,struct bufferevent * dst,int ignore_wm)151 be_pair_transfer(struct bufferevent *src, struct bufferevent *dst,
152 int ignore_wm)
153 {
154 size_t src_size, dst_size;
155 size_t n;
156
157 evbuffer_unfreeze(src->output, 1);
158 evbuffer_unfreeze(dst->input, 0);
159
160 if (dst->wm_read.high) {
161 dst_size = evbuffer_get_length(dst->input);
162 if (dst_size < dst->wm_read.high) {
163 n = dst->wm_read.high - dst_size;
164 evbuffer_remove_buffer(src->output, dst->input, n);
165 } else {
166 if (!ignore_wm)
167 goto done;
168 n = evbuffer_get_length(src->output);
169 evbuffer_add_buffer(dst->input, src->output);
170 }
171 } else {
172 n = evbuffer_get_length(src->output);
173 evbuffer_add_buffer(dst->input, src->output);
174 }
175
176 if (n) {
177 BEV_RESET_GENERIC_READ_TIMEOUT(dst);
178
179 if (evbuffer_get_length(dst->output))
180 BEV_RESET_GENERIC_WRITE_TIMEOUT(dst);
181 else
182 BEV_DEL_GENERIC_WRITE_TIMEOUT(dst);
183 }
184
185 src_size = evbuffer_get_length(src->output);
186 dst_size = evbuffer_get_length(dst->input);
187
188 if (dst_size >= dst->wm_read.low) {
189 _bufferevent_run_readcb(dst);
190 }
191 if (src_size <= src->wm_write.low) {
192 _bufferevent_run_writecb(src);
193 }
194 done:
195 evbuffer_freeze(src->output, 1);
196 evbuffer_freeze(dst->input, 0);
197 }
198
199 static inline int
be_pair_wants_to_talk(struct bufferevent_pair * src,struct bufferevent_pair * dst)200 be_pair_wants_to_talk(struct bufferevent_pair *src,
201 struct bufferevent_pair *dst)
202 {
203 return (downcast(src)->enabled & EV_WRITE) &&
204 (downcast(dst)->enabled & EV_READ) &&
205 !dst->bev.read_suspended &&
206 evbuffer_get_length(downcast(src)->output);
207 }
208
209 static void
be_pair_outbuf_cb(struct evbuffer * outbuf,const struct evbuffer_cb_info * info,void * arg)210 be_pair_outbuf_cb(struct evbuffer *outbuf,
211 const struct evbuffer_cb_info *info, void *arg)
212 {
213 struct bufferevent_pair *bev_pair = arg;
214 struct bufferevent_pair *partner = bev_pair->partner;
215
216 incref_and_lock(downcast(bev_pair));
217
218 if (info->n_added > info->n_deleted && partner) {
219 /* We got more data. If the other side's reading, then
220 hand it over. */
221 if (be_pair_wants_to_talk(bev_pair, partner)) {
222 be_pair_transfer(downcast(bev_pair), downcast(partner), 0);
223 }
224 }
225
226 decref_and_unlock(downcast(bev_pair));
227 }
228
229 static int
be_pair_enable(struct bufferevent * bufev,short events)230 be_pair_enable(struct bufferevent *bufev, short events)
231 {
232 struct bufferevent_pair *bev_p = upcast(bufev);
233 struct bufferevent_pair *partner = bev_p->partner;
234
235 incref_and_lock(bufev);
236
237 if (events & EV_READ) {
238 BEV_RESET_GENERIC_READ_TIMEOUT(bufev);
239 }
240 if ((events & EV_WRITE) && evbuffer_get_length(bufev->output))
241 BEV_RESET_GENERIC_WRITE_TIMEOUT(bufev);
242
243 /* We're starting to read! Does the other side have anything to write?*/
244 if ((events & EV_READ) && partner &&
245 be_pair_wants_to_talk(partner, bev_p)) {
246 be_pair_transfer(downcast(partner), bufev, 0);
247 }
248 /* We're starting to write! Does the other side want to read? */
249 if ((events & EV_WRITE) && partner &&
250 be_pair_wants_to_talk(bev_p, partner)) {
251 be_pair_transfer(bufev, downcast(partner), 0);
252 }
253 decref_and_unlock(bufev);
254 return 0;
255 }
256
257 static int
be_pair_disable(struct bufferevent * bev,short events)258 be_pair_disable(struct bufferevent *bev, short events)
259 {
260 if (events & EV_READ) {
261 BEV_DEL_GENERIC_READ_TIMEOUT(bev);
262 }
263 if (events & EV_WRITE)
264 BEV_DEL_GENERIC_WRITE_TIMEOUT(bev);
265 return 0;
266 }
267
268 static void
be_pair_destruct(struct bufferevent * bev)269 be_pair_destruct(struct bufferevent *bev)
270 {
271 struct bufferevent_pair *bev_p = upcast(bev);
272
273 if (bev_p->partner) {
274 bev_p->partner->partner = NULL;
275 bev_p->partner = NULL;
276 }
277
278 _bufferevent_del_generic_timeout_cbs(bev);
279 }
280
281 static int
be_pair_flush(struct bufferevent * bev,short iotype,enum bufferevent_flush_mode mode)282 be_pair_flush(struct bufferevent *bev, short iotype,
283 enum bufferevent_flush_mode mode)
284 {
285 struct bufferevent_pair *bev_p = upcast(bev);
286 struct bufferevent *partner;
287 incref_and_lock(bev);
288 if (!bev_p->partner)
289 return -1;
290
291 partner = downcast(bev_p->partner);
292
293 if (mode == BEV_NORMAL)
294 return 0;
295
296 if ((iotype & EV_READ) != 0)
297 be_pair_transfer(partner, bev, 1);
298
299 if ((iotype & EV_WRITE) != 0)
300 be_pair_transfer(bev, partner, 1);
301
302 if (mode == BEV_FINISHED) {
303 _bufferevent_run_eventcb(partner, iotype|BEV_EVENT_EOF);
304 }
305 decref_and_unlock(bev);
306 return 0;
307 }
308
309 struct bufferevent *
bufferevent_pair_get_partner(struct bufferevent * bev)310 bufferevent_pair_get_partner(struct bufferevent *bev)
311 {
312 struct bufferevent_pair *bev_p;
313 struct bufferevent *partner = NULL;
314 bev_p = upcast(bev);
315 if (! bev_p)
316 return NULL;
317
318 incref_and_lock(bev);
319 if (bev_p->partner)
320 partner = downcast(bev_p->partner);
321 decref_and_unlock(bev);
322 return partner;
323 }
324
325 const struct bufferevent_ops bufferevent_ops_pair = {
326 "pair_elt",
327 evutil_offsetof(struct bufferevent_pair, bev.bev),
328 be_pair_enable,
329 be_pair_disable,
330 be_pair_destruct,
331 _bufferevent_generic_adj_timeouts,
332 be_pair_flush,
333 NULL, /* ctrl */
334 };
335