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 #include "event2/event-config.h" 27 #include "evconfig-private.h" 28 29 #include <sys/types.h> 30 31 #ifdef _WIN32 32 #include <winsock2.h> 33 #endif 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 * 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 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 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 * 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 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 151 be_pair_transfer(struct bufferevent *src, struct bufferevent *dst, 152 int ignore_wm) 153 { 154 size_t 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 bufferevent_trigger_nolock_(dst, EV_READ, 0); 186 bufferevent_trigger_nolock_(src, EV_WRITE, 0); 187 done: 188 evbuffer_freeze(src->output, 1); 189 evbuffer_freeze(dst->input, 0); 190 } 191 192 static inline int 193 be_pair_wants_to_talk(struct bufferevent_pair *src, 194 struct bufferevent_pair *dst) 195 { 196 return (downcast(src)->enabled & EV_WRITE) && 197 (downcast(dst)->enabled & EV_READ) && 198 !dst->bev.read_suspended && 199 evbuffer_get_length(downcast(src)->output); 200 } 201 202 static void 203 be_pair_outbuf_cb(struct evbuffer *outbuf, 204 const struct evbuffer_cb_info *info, void *arg) 205 { 206 struct bufferevent_pair *bev_pair = arg; 207 struct bufferevent_pair *partner = bev_pair->partner; 208 209 incref_and_lock(downcast(bev_pair)); 210 211 if (info->n_added > info->n_deleted && partner) { 212 /* We got more data. If the other side's reading, then 213 hand it over. */ 214 if (be_pair_wants_to_talk(bev_pair, partner)) { 215 be_pair_transfer(downcast(bev_pair), downcast(partner), 0); 216 } 217 } 218 219 decref_and_unlock(downcast(bev_pair)); 220 } 221 222 static int 223 be_pair_enable(struct bufferevent *bufev, short events) 224 { 225 struct bufferevent_pair *bev_p = upcast(bufev); 226 struct bufferevent_pair *partner = bev_p->partner; 227 228 incref_and_lock(bufev); 229 230 if (events & EV_READ) { 231 BEV_RESET_GENERIC_READ_TIMEOUT(bufev); 232 } 233 if ((events & EV_WRITE) && evbuffer_get_length(bufev->output)) 234 BEV_RESET_GENERIC_WRITE_TIMEOUT(bufev); 235 236 /* We're starting to read! Does the other side have anything to write?*/ 237 if ((events & EV_READ) && partner && 238 be_pair_wants_to_talk(partner, bev_p)) { 239 be_pair_transfer(downcast(partner), bufev, 0); 240 } 241 /* We're starting to write! Does the other side want to read? */ 242 if ((events & EV_WRITE) && partner && 243 be_pair_wants_to_talk(bev_p, partner)) { 244 be_pair_transfer(bufev, downcast(partner), 0); 245 } 246 decref_and_unlock(bufev); 247 return 0; 248 } 249 250 static int 251 be_pair_disable(struct bufferevent *bev, short events) 252 { 253 if (events & EV_READ) { 254 BEV_DEL_GENERIC_READ_TIMEOUT(bev); 255 } 256 if (events & EV_WRITE) { 257 BEV_DEL_GENERIC_WRITE_TIMEOUT(bev); 258 } 259 return 0; 260 } 261 262 static void 263 be_pair_unlink(struct bufferevent *bev) 264 { 265 struct bufferevent_pair *bev_p = upcast(bev); 266 267 if (bev_p->partner) { 268 bev_p->partner->partner = NULL; 269 bev_p->partner = NULL; 270 } 271 } 272 273 static int 274 be_pair_flush(struct bufferevent *bev, short iotype, 275 enum bufferevent_flush_mode mode) 276 { 277 struct bufferevent_pair *bev_p = upcast(bev); 278 struct bufferevent *partner; 279 incref_and_lock(bev); 280 if (!bev_p->partner) 281 return -1; 282 283 partner = downcast(bev_p->partner); 284 285 if (mode == BEV_NORMAL) 286 return 0; 287 288 if ((iotype & EV_READ) != 0) 289 be_pair_transfer(partner, bev, 1); 290 291 if ((iotype & EV_WRITE) != 0) 292 be_pair_transfer(bev, partner, 1); 293 294 if (mode == BEV_FINISHED) { 295 bufferevent_run_eventcb_(partner, iotype|BEV_EVENT_EOF, 0); 296 } 297 decref_and_unlock(bev); 298 return 0; 299 } 300 301 struct bufferevent * 302 bufferevent_pair_get_partner(struct bufferevent *bev) 303 { 304 struct bufferevent_pair *bev_p; 305 struct bufferevent *partner = NULL; 306 bev_p = upcast(bev); 307 if (! bev_p) 308 return NULL; 309 310 incref_and_lock(bev); 311 if (bev_p->partner) 312 partner = downcast(bev_p->partner); 313 decref_and_unlock(bev); 314 return partner; 315 } 316 317 const struct bufferevent_ops bufferevent_ops_pair = { 318 "pair_elt", 319 evutil_offsetof(struct bufferevent_pair, bev.bev), 320 be_pair_enable, 321 be_pair_disable, 322 be_pair_unlink, 323 NULL, /* be_pair_destruct, */ 324 bufferevent_generic_adj_timeouts_, 325 be_pair_flush, 326 NULL, /* ctrl */ 327 }; 328