1 /* $NetBSD: bufferevent_pair.c,v 1.1.1.1 2013/12/27 23:31:17 christos Exp $ */ 2 3 /* 4 * Copyright (c) 2009-2012 Niels Provos, Nick Mathewson 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. The name of the author may not be used to endorse or promote products 15 * derived from this software without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 */ 28 #include "event2/event-config.h" 29 #include "evconfig-private.h" 30 31 #include <sys/types.h> 32 33 #ifdef _WIN32 34 #include <winsock2.h> 35 #endif 36 37 #include "event2/util.h" 38 #include "event2/buffer.h" 39 #include "event2/bufferevent.h" 40 #include "event2/bufferevent_struct.h" 41 #include "event2/event.h" 42 #include "defer-internal.h" 43 #include "bufferevent-internal.h" 44 #include "mm-internal.h" 45 #include "util-internal.h" 46 47 struct bufferevent_pair { 48 struct bufferevent_private bev; 49 struct bufferevent_pair *partner; 50 }; 51 52 53 /* Given a bufferevent that's really a bev part of a bufferevent_pair, 54 * return that bufferevent_filtered. Returns NULL otherwise.*/ 55 static inline struct bufferevent_pair * 56 upcast(struct bufferevent *bev) 57 { 58 struct bufferevent_pair *bev_p; 59 if (bev->be_ops != &bufferevent_ops_pair) 60 return NULL; 61 bev_p = EVUTIL_UPCAST(bev, struct bufferevent_pair, bev.bev); 62 EVUTIL_ASSERT(bev_p->bev.bev.be_ops == &bufferevent_ops_pair); 63 return bev_p; 64 } 65 66 #define downcast(bev_pair) (&(bev_pair)->bev.bev) 67 68 static inline void 69 incref_and_lock(struct bufferevent *b) 70 { 71 struct bufferevent_pair *bevp; 72 bufferevent_incref_and_lock_(b); 73 bevp = upcast(b); 74 if (bevp->partner) 75 bufferevent_incref_and_lock_(downcast(bevp->partner)); 76 } 77 78 static inline void 79 decref_and_unlock(struct bufferevent *b) 80 { 81 struct bufferevent_pair *bevp = upcast(b); 82 if (bevp->partner) 83 bufferevent_decref_and_unlock_(downcast(bevp->partner)); 84 bufferevent_decref_and_unlock_(b); 85 } 86 87 /* XXX Handle close */ 88 89 static void be_pair_outbuf_cb(struct evbuffer *, 90 const struct evbuffer_cb_info *, void *); 91 92 static struct bufferevent_pair * 93 bufferevent_pair_elt_new(struct event_base *base, 94 int options) 95 { 96 struct bufferevent_pair *bufev; 97 if (! (bufev = mm_calloc(1, sizeof(struct bufferevent_pair)))) 98 return NULL; 99 if (bufferevent_init_common_(&bufev->bev, base, &bufferevent_ops_pair, 100 options)) { 101 mm_free(bufev); 102 return NULL; 103 } 104 if (!evbuffer_add_cb(bufev->bev.bev.output, be_pair_outbuf_cb, bufev)) { 105 bufferevent_free(downcast(bufev)); 106 return NULL; 107 } 108 109 bufferevent_init_generic_timeout_cbs_(&bufev->bev.bev); 110 111 return bufev; 112 } 113 114 int 115 bufferevent_pair_new(struct event_base *base, int options, 116 struct bufferevent *pair[2]) 117 { 118 struct bufferevent_pair *bufev1 = NULL, *bufev2 = NULL; 119 int tmp_options; 120 121 options |= BEV_OPT_DEFER_CALLBACKS; 122 tmp_options = options & ~BEV_OPT_THREADSAFE; 123 124 bufev1 = bufferevent_pair_elt_new(base, options); 125 if (!bufev1) 126 return -1; 127 bufev2 = bufferevent_pair_elt_new(base, tmp_options); 128 if (!bufev2) { 129 bufferevent_free(downcast(bufev1)); 130 return -1; 131 } 132 133 if (options & BEV_OPT_THREADSAFE) { 134 /*XXXX check return */ 135 bufferevent_enable_locking_(downcast(bufev2), bufev1->bev.lock); 136 } 137 138 bufev1->partner = bufev2; 139 bufev2->partner = bufev1; 140 141 evbuffer_freeze(downcast(bufev1)->input, 0); 142 evbuffer_freeze(downcast(bufev1)->output, 1); 143 evbuffer_freeze(downcast(bufev2)->input, 0); 144 evbuffer_freeze(downcast(bufev2)->output, 1); 145 146 pair[0] = downcast(bufev1); 147 pair[1] = downcast(bufev2); 148 149 return 0; 150 } 151 152 static void 153 be_pair_transfer(struct bufferevent *src, struct bufferevent *dst, 154 int ignore_wm) 155 { 156 size_t src_size, dst_size; 157 size_t n; 158 159 evbuffer_unfreeze(src->output, 1); 160 evbuffer_unfreeze(dst->input, 0); 161 162 if (dst->wm_read.high) { 163 dst_size = evbuffer_get_length(dst->input); 164 if (dst_size < dst->wm_read.high) { 165 n = dst->wm_read.high - dst_size; 166 evbuffer_remove_buffer(src->output, dst->input, n); 167 } else { 168 if (!ignore_wm) 169 goto done; 170 n = evbuffer_get_length(src->output); 171 evbuffer_add_buffer(dst->input, src->output); 172 } 173 } else { 174 n = evbuffer_get_length(src->output); 175 evbuffer_add_buffer(dst->input, src->output); 176 } 177 178 if (n) { 179 BEV_RESET_GENERIC_READ_TIMEOUT(dst); 180 181 if (evbuffer_get_length(dst->output)) 182 BEV_RESET_GENERIC_WRITE_TIMEOUT(dst); 183 else 184 BEV_DEL_GENERIC_WRITE_TIMEOUT(dst); 185 } 186 187 src_size = evbuffer_get_length(src->output); 188 dst_size = evbuffer_get_length(dst->input); 189 190 if (dst_size >= dst->wm_read.low) { 191 bufferevent_run_readcb_(dst); 192 } 193 if (src_size <= src->wm_write.low) { 194 bufferevent_run_writecb_(src); 195 } 196 done: 197 evbuffer_freeze(src->output, 1); 198 evbuffer_freeze(dst->input, 0); 199 } 200 201 static inline int 202 be_pair_wants_to_talk(struct bufferevent_pair *src, 203 struct bufferevent_pair *dst) 204 { 205 return (downcast(src)->enabled & EV_WRITE) && 206 (downcast(dst)->enabled & EV_READ) && 207 !dst->bev.read_suspended && 208 evbuffer_get_length(downcast(src)->output); 209 } 210 211 static void 212 be_pair_outbuf_cb(struct evbuffer *outbuf, 213 const struct evbuffer_cb_info *info, void *arg) 214 { 215 struct bufferevent_pair *bev_pair = arg; 216 struct bufferevent_pair *partner = bev_pair->partner; 217 218 incref_and_lock(downcast(bev_pair)); 219 220 if (info->n_added > info->n_deleted && partner) { 221 /* We got more data. If the other side's reading, then 222 hand it over. */ 223 if (be_pair_wants_to_talk(bev_pair, partner)) { 224 be_pair_transfer(downcast(bev_pair), downcast(partner), 0); 225 } 226 } 227 228 decref_and_unlock(downcast(bev_pair)); 229 } 230 231 static int 232 be_pair_enable(struct bufferevent *bufev, short events) 233 { 234 struct bufferevent_pair *bev_p = upcast(bufev); 235 struct bufferevent_pair *partner = bev_p->partner; 236 237 incref_and_lock(bufev); 238 239 if (events & EV_READ) { 240 BEV_RESET_GENERIC_READ_TIMEOUT(bufev); 241 } 242 if ((events & EV_WRITE) && evbuffer_get_length(bufev->output)) 243 BEV_RESET_GENERIC_WRITE_TIMEOUT(bufev); 244 245 /* We're starting to read! Does the other side have anything to write?*/ 246 if ((events & EV_READ) && partner && 247 be_pair_wants_to_talk(partner, bev_p)) { 248 be_pair_transfer(downcast(partner), bufev, 0); 249 } 250 /* We're starting to write! Does the other side want to read? */ 251 if ((events & EV_WRITE) && partner && 252 be_pair_wants_to_talk(bev_p, partner)) { 253 be_pair_transfer(bufev, downcast(partner), 0); 254 } 255 decref_and_unlock(bufev); 256 return 0; 257 } 258 259 static int 260 be_pair_disable(struct bufferevent *bev, short events) 261 { 262 if (events & EV_READ) { 263 BEV_DEL_GENERIC_READ_TIMEOUT(bev); 264 } 265 if (events & EV_WRITE) { 266 BEV_DEL_GENERIC_WRITE_TIMEOUT(bev); 267 } 268 return 0; 269 } 270 271 static void 272 be_pair_destruct(struct bufferevent *bev) 273 { 274 struct bufferevent_pair *bev_p = upcast(bev); 275 276 if (bev_p->partner) { 277 bev_p->partner->partner = NULL; 278 bev_p->partner = NULL; 279 } 280 281 bufferevent_del_generic_timeout_cbs_(bev); 282 } 283 284 static int 285 be_pair_flush(struct bufferevent *bev, short iotype, 286 enum bufferevent_flush_mode mode) 287 { 288 struct bufferevent_pair *bev_p = upcast(bev); 289 struct bufferevent *partner; 290 incref_and_lock(bev); 291 if (!bev_p->partner) 292 return -1; 293 294 partner = downcast(bev_p->partner); 295 296 if (mode == BEV_NORMAL) 297 return 0; 298 299 if ((iotype & EV_READ) != 0) 300 be_pair_transfer(partner, bev, 1); 301 302 if ((iotype & EV_WRITE) != 0) 303 be_pair_transfer(bev, partner, 1); 304 305 if (mode == BEV_FINISHED) { 306 bufferevent_run_eventcb_(partner, iotype|BEV_EVENT_EOF); 307 } 308 decref_and_unlock(bev); 309 return 0; 310 } 311 312 struct bufferevent * 313 bufferevent_pair_get_partner(struct bufferevent *bev) 314 { 315 struct bufferevent_pair *bev_p; 316 struct bufferevent *partner; 317 bev_p = upcast(bev); 318 if (! bev_p) 319 return NULL; 320 321 incref_and_lock(bev); 322 partner = downcast(bev_p->partner); 323 decref_and_unlock(bev); 324 return partner; 325 } 326 327 const struct bufferevent_ops bufferevent_ops_pair = { 328 "pair_elt", 329 evutil_offsetof(struct bufferevent_pair, bev.bev), 330 be_pair_enable, 331 be_pair_disable, 332 be_pair_destruct, 333 bufferevent_generic_adj_timeouts_, 334 be_pair_flush, 335 NULL, /* ctrl */ 336 }; 337