lib/frr_zmq.c

   1 /*
   2  * libzebra ZeroMQ bindings
   3  * Copyright (C) 2015  David Lamparter
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License as published by the Free
   7  * Software Foundation; either version 2 of the License, or (at your option)
   8  * any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  13  * more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; see the file COPYING; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  18  */
  19
  20 /*
  21  * IF YOU MODIFY THIS FILE PLEASE RUN `make check` and ensure that
  22  * the test_zmq.c unit test is still working.  There are dependencies
  23  * between the two that are extremely fragile.  My understanding
  24  * is that there is specialized ownership of the cb pointer based
  25  * upon what is happening.  Those assumptions are supposed to be
  26  * tested in the test_zmq.c
  27  */
  28 #include <zebra.h>
  29 #include <zmq.h>
  30
  31 #include "thread.h"
  32 #include "memory.h"
  33 #include "frr_zmq.h"
  34 #include "log.h"
  35 #include "lib_errors.h"
  36
  37 DEFINE_MTYPE_STATIC(LIB, ZEROMQ_CB, "ZeroMQ callback");
  38
  39 /* libzmq's context */
  40 void *frrzmq_context = NULL;
  41 static unsigned frrzmq_initcount = 0;
  42
  43 void frrzmq_init(void)
  44 {
  45         if (frrzmq_initcount++ == 0) {
  46                 frrzmq_context = zmq_ctx_new();
  47                 zmq_ctx_set(frrzmq_context, ZMQ_IPV6, 1);
  48         }
  49 }
  50
  51 void frrzmq_finish(void)
  52 {
  53         if (--frrzmq_initcount == 0) {
  54                 zmq_ctx_term(frrzmq_context);
  55                 frrzmq_context = NULL;
  56         }
  57 }
  58
  59 static int frrzmq_read_msg(struct thread *t)
  60 {
  61         struct frrzmq_cb **cbp = THREAD_ARG(t);
  62         struct frrzmq_cb *cb;
  63         zmq_msg_t msg;
  64         unsigned partno;
  65         unsigned char read = 0;
  66         int ret, more;
  67         size_t moresz;
  68
  69         if (!cbp)
  70                 return 1;
  71         cb = (*cbp);
  72         if (!cb || !cb->zmqsock)
  73                 return 1;
  74
  75         while (1) {
  76                 zmq_pollitem_t polli = {.socket = cb->zmqsock,
  77                                         .events = ZMQ_POLLIN};
  78                 ret = zmq_poll(&polli, 1, 0);
  79
  80                 if (ret < 0)
  81                         goto out_err;
  82
  83                 if (!(polli.revents & ZMQ_POLLIN))
  84                         break;
  85
  86                 if (cb->read.cb_msg) {
  87                         cb->in_cb = true;
  88                         cb->read.cb_msg(cb->read.arg, cb->zmqsock);
  89                         cb->in_cb = false;
  90
  91                         read = 1;
  92
  93                         if (cb->read.cancelled) {
  94                                 frrzmq_check_events(cbp, &cb->write,
  95                                                     ZMQ_POLLOUT);
  96                                 cb->read.thread = NULL;
  97                                 if (cb->write.cancelled && !cb->write.thread)
  98                                         XFREE(MTYPE_ZEROMQ_CB, *cbp);
  99
 100                                 return 0;
 101                         }
 102                         continue;
 103                 }
 104
 105                 partno = 0;
 106                 if (zmq_msg_init(&msg))
 107                         goto out_err;
 108                 do {
 109                         ret = zmq_msg_recv(&msg, cb->zmqsock, ZMQ_NOBLOCK);
 110                         if (ret < 0) {
 111                                 if (errno == EAGAIN)
 112                                         break;
 113
 114                                 zmq_msg_close(&msg);
 115                                 goto out_err;
 116                         }
 117                         read = 1;
 118
 119                         cb->in_cb = true;
 120                         cb->read.cb_part(cb->read.arg, cb->zmqsock, &msg,
 121                                          partno);
 122                         cb->in_cb = false;
 123
 124                         if (cb->read.cancelled) {
 125                                 zmq_msg_close(&msg);
 126                                 frrzmq_check_events(cbp, &cb->write,
 127                                                     ZMQ_POLLOUT);
 128                                 cb->read.thread = NULL;
 129                                 if (cb->write.cancelled && !cb->write.thread)
 130                                         XFREE(MTYPE_ZEROMQ_CB, *cbp);
 131
 132                                 return 0;
 133                         }
 134
 135                         /* cb_part may have read additional parts of the
 136                          * message; don't use zmq_msg_more here */
 137                         moresz = sizeof(more);
 138                         more = 0;
 139                         ret = zmq_getsockopt(cb->zmqsock, ZMQ_RCVMORE, &more,
 140                                              &moresz);
 141                         if (ret < 0) {
 142                                 zmq_msg_close(&msg);
 143                                 goto out_err;
 144                         }
 145
 146                         partno++;
 147                 } while (more);
 148                 zmq_msg_close(&msg);
 149         }
 150
 151         if (read)
 152                 frrzmq_check_events(cbp, &cb->write, ZMQ_POLLOUT);
 153
 154         thread_add_read(t->master, frrzmq_read_msg, cbp,
 155                         cb->fd, &cb->read.thread);
 156         return 0;
 157
 158 out_err:
 159         flog_err(EC_LIB_ZMQ, "ZeroMQ read error: %s(%d)", strerror(errno),
 160                  errno);
 161         if (cb->read.cb_error)
 162                 cb->read.cb_error(cb->read.arg, cb->zmqsock);
 163         return 1;
 164 }
 165
 166 int _frrzmq_thread_add_read(const struct xref_threadsched *xref,
 167                             struct thread_master *master,
 168                             void (*msgfunc)(void *arg, void *zmqsock),
 169                             void (*partfunc)(void *arg, void *zmqsock,
 170                                              zmq_msg_t *msg, unsigned partnum),
 171                             void (*errfunc)(void *arg, void *zmqsock),
 172                             void *arg, void *zmqsock,
 173                             struct frrzmq_cb **cbp)
 174 {
 175         int fd, events;
 176         size_t len;
 177         struct frrzmq_cb *cb;
 178
 179         if (!cbp)
 180                 return -1;
 181         if (!(msgfunc || partfunc) || (msgfunc && partfunc))
 182                 return -1;
 183         len = sizeof(fd);
 184         if (zmq_getsockopt(zmqsock, ZMQ_FD, &fd, &len))
 185                 return -1;
 186         len = sizeof(events);
 187         if (zmq_getsockopt(zmqsock, ZMQ_EVENTS, &events, &len))
 188                 return -1;
 189
 190         if (*cbp)
 191                 cb = *cbp;
 192         else {
 193                 cb = XCALLOC(MTYPE_ZEROMQ_CB, sizeof(struct frrzmq_cb));
 194                 cb->write.cancelled = true;
 195                 *cbp = cb;
 196         }
 197
 198         cb->zmqsock = zmqsock;
 199         cb->fd = fd;
 200         cb->read.arg = arg;
 201         cb->read.cb_msg = msgfunc;
 202         cb->read.cb_part = partfunc;
 203         cb->read.cb_error = errfunc;
 204         cb->read.cancelled = false;
 205         cb->in_cb = false;
 206
 207         if (events & ZMQ_POLLIN) {
 208                 thread_cancel(&cb->read.thread);
 209
 210                 thread_add_event(master, frrzmq_read_msg, cbp, fd,
 211                                   &cb->read.thread);
 212         } else
 213                 thread_add_read(master, frrzmq_read_msg, cbp, fd,
 214                                 &cb->read.thread);
 215         return 0;
 216 }
 217
 218 static int frrzmq_write_msg(struct thread *t)
 219 {
 220         struct frrzmq_cb **cbp = THREAD_ARG(t);
 221         struct frrzmq_cb *cb;
 222         unsigned char written = 0;
 223         int ret;
 224
 225         if (!cbp)
 226                 return 1;
 227         cb = (*cbp);
 228         if (!cb || !cb->zmqsock)
 229                 return 1;
 230
 231         while (1) {
 232                 zmq_pollitem_t polli = {.socket = cb->zmqsock,
 233                                         .events = ZMQ_POLLOUT};
 234                 ret = zmq_poll(&polli, 1, 0);
 235
 236                 if (ret < 0)
 237                         goto out_err;
 238
 239                 if (!(polli.revents & ZMQ_POLLOUT))
 240                         break;
 241
 242                 if (cb->write.cb_msg) {
 243                         cb->in_cb = true;
 244                         cb->write.cb_msg(cb->write.arg, cb->zmqsock);
 245                         cb->in_cb = false;
 246
 247                         written = 1;
 248
 249                         if (cb->write.cancelled) {
 250                                 frrzmq_check_events(cbp, &cb->read, ZMQ_POLLIN);
 251                                 cb->write.thread = NULL;
 252                                 if (cb->read.cancelled && !cb->read.thread)
 253                                         XFREE(MTYPE_ZEROMQ_CB, *cbp);
 254
 255                                 return 0;
 256                         }
 257                         continue;
 258                 }
 259         }
 260
 261         if (written)
 262                 frrzmq_check_events(cbp, &cb->read, ZMQ_POLLIN);
 263
 264         thread_add_write(t->master, frrzmq_write_msg, cbp,
 265                          cb->fd, &cb->write.thread);
 266         return 0;
 267
 268 out_err:
 269         flog_err(EC_LIB_ZMQ, "ZeroMQ write error: %s(%d)", strerror(errno),
 270                  errno);
 271         if (cb->write.cb_error)
 272                 cb->write.cb_error(cb->write.arg, cb->zmqsock);
 273         return 1;
 274 }
 275
 276 int _frrzmq_thread_add_write(const struct xref_threadsched *xref,
 277                              struct thread_master *master,
 278                              void (*msgfunc)(void *arg, void *zmqsock),
 279                              void (*errfunc)(void *arg, void *zmqsock),
 280                              void *arg, void *zmqsock, struct frrzmq_cb **cbp)
 281 {
 282         int fd, events;
 283         size_t len;
 284         struct frrzmq_cb *cb;
 285
 286         if (!cbp)
 287                 return -1;
 288         if (!msgfunc)
 289                 return -1;
 290         len = sizeof(fd);
 291         if (zmq_getsockopt(zmqsock, ZMQ_FD, &fd, &len))
 292                 return -1;
 293         len = sizeof(events);
 294         if (zmq_getsockopt(zmqsock, ZMQ_EVENTS, &events, &len))
 295                 return -1;
 296
 297         if (*cbp)
 298                 cb = *cbp;
 299         else {
 300                 cb = XCALLOC(MTYPE_ZEROMQ_CB, sizeof(struct frrzmq_cb));
 301                 cb->read.cancelled = true;
 302                 *cbp = cb;
 303         }
 304
 305         cb->zmqsock = zmqsock;
 306         cb->fd = fd;
 307         cb->write.arg = arg;
 308         cb->write.cb_msg = msgfunc;
 309         cb->write.cb_part = NULL;
 310         cb->write.cb_error = errfunc;
 311         cb->write.cancelled = false;
 312         cb->in_cb = false;
 313
 314         if (events & ZMQ_POLLOUT) {
 315                 thread_cancel(&cb->write.thread);
 316
 317                 _thread_add_event(xref, master, frrzmq_write_msg, cbp, fd,
 318                                   &cb->write.thread);
 319         } else
 320                 thread_add_write(master, frrzmq_write_msg, cbp, fd,
 321                                  &cb->write.thread);
 322         return 0;
 323 }
 324
 325 void frrzmq_thread_cancel(struct frrzmq_cb **cb, struct cb_core *core)
 326 {
 327         if (!cb || !*cb)
 328                 return;
 329         core->cancelled = true;
 330         thread_cancel(&core->thread);
 331
 332         /* If cancelled from within a callback, don't try to free memory
 333          * in this path.
 334          */
 335         if ((*cb)->in_cb)
 336                 return;
 337
 338         /* Ok to free the callback context if no more ... context. */
 339         if ((*cb)->read.cancelled && !(*cb)->read.thread
 340             && (*cb)->write.cancelled && ((*cb)->write.thread == NULL))
 341                 XFREE(MTYPE_ZEROMQ_CB, *cb);
 342 }
 343
 344 void frrzmq_check_events(struct frrzmq_cb **cbp, struct cb_core *core,
 345                          int event)
 346 {
 347         struct frrzmq_cb *cb;
 348         int events;
 349         size_t len;
 350
 351         if (!cbp)
 352                 return;
 353         cb = (*cbp);
 354         if (!cb || !cb->zmqsock)
 355                 return;
 356
 357         len = sizeof(events);
 358         if (zmq_getsockopt(cb->zmqsock, ZMQ_EVENTS, &events, &len))
 359                 return;
 360         if ((events & event) && core->thread && !core->cancelled) {
 361                 struct thread_master *tm = core->thread->master;
 362
 363                 thread_cancel(&core->thread);
 364
 365                 if (event == ZMQ_POLLIN)
 366                         thread_add_event(tm, frrzmq_read_msg,
 367                                          cbp, cb->fd, &core->thread);
 368                 else
 369                         thread_add_event(tm, frrzmq_write_msg,
 370                                          cbp, cb->fd, &core->thread);
 371         }
 372 }