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 void 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;
  71         cb = (*cbp);
  72         if (!cb || !cb->zmqsock)
  73                 return;
  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;
 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;
 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;
 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 }
 164
 165 int _frrzmq_thread_add_read(const struct xref_threadsched *xref,
 166                             struct thread_master *master,
 167                             void (*msgfunc)(void *arg, void *zmqsock),
 168                             void (*partfunc)(void *arg, void *zmqsock,
 169                                              zmq_msg_t *msg, unsigned partnum),
 170                             void (*errfunc)(void *arg, void *zmqsock),
 171                             void *arg, void *zmqsock,
 172                             struct frrzmq_cb **cbp)
 173 {
 174         int fd, events;
 175         size_t len;
 176         struct frrzmq_cb *cb;
 177
 178         if (!cbp)
 179                 return -1;
 180         if (!(msgfunc || partfunc) || (msgfunc && partfunc))
 181                 return -1;
 182         len = sizeof(fd);
 183         if (zmq_getsockopt(zmqsock, ZMQ_FD, &fd, &len))
 184                 return -1;
 185         len = sizeof(events);
 186         if (zmq_getsockopt(zmqsock, ZMQ_EVENTS, &events, &len))
 187                 return -1;
 188
 189         if (*cbp)
 190                 cb = *cbp;
 191         else {
 192                 cb = XCALLOC(MTYPE_ZEROMQ_CB, sizeof(struct frrzmq_cb));
 193                 cb->write.cancelled = true;
 194                 *cbp = cb;
 195         }
 196
 197         cb->zmqsock = zmqsock;
 198         cb->fd = fd;
 199         cb->read.arg = arg;
 200         cb->read.cb_msg = msgfunc;
 201         cb->read.cb_part = partfunc;
 202         cb->read.cb_error = errfunc;
 203         cb->read.cancelled = false;
 204         cb->in_cb = false;
 205
 206         if (events & ZMQ_POLLIN) {
 207                 thread_cancel(&cb->read.thread);
 208
 209                 thread_add_event(master, frrzmq_read_msg, cbp, fd,
 210                                   &cb->read.thread);
 211         } else
 212                 thread_add_read(master, frrzmq_read_msg, cbp, fd,
 213                                 &cb->read.thread);
 214         return 0;
 215 }
 216
 217 static void frrzmq_write_msg(struct thread *t)
 218 {
 219         struct frrzmq_cb **cbp = THREAD_ARG(t);
 220         struct frrzmq_cb *cb;
 221         unsigned char written = 0;
 222         int ret;
 223
 224         if (!cbp)
 225                 return;
 226         cb = (*cbp);
 227         if (!cb || !cb->zmqsock)
 228                 return;
 229
 230         while (1) {
 231                 zmq_pollitem_t polli = {.socket = cb->zmqsock,
 232                                         .events = ZMQ_POLLOUT};
 233                 ret = zmq_poll(&polli, 1, 0);
 234
 235                 if (ret < 0)
 236                         goto out_err;
 237
 238                 if (!(polli.revents & ZMQ_POLLOUT))
 239                         break;
 240
 241                 if (cb->write.cb_msg) {
 242                         cb->in_cb = true;
 243                         cb->write.cb_msg(cb->write.arg, cb->zmqsock);
 244                         cb->in_cb = false;
 245
 246                         written = 1;
 247
 248                         if (cb->write.cancelled) {
 249                                 frrzmq_check_events(cbp, &cb->read, ZMQ_POLLIN);
 250                                 cb->write.thread = NULL;
 251                                 if (cb->read.cancelled && !cb->read.thread)
 252                                         XFREE(MTYPE_ZEROMQ_CB, *cbp);
 253
 254                                 return;
 255                         }
 256                         continue;
 257                 }
 258         }
 259
 260         if (written)
 261                 frrzmq_check_events(cbp, &cb->read, ZMQ_POLLIN);
 262
 263         thread_add_write(t->master, frrzmq_write_msg, cbp,
 264                          cb->fd, &cb->write.thread);
 265         return;
 266
 267 out_err:
 268         flog_err(EC_LIB_ZMQ, "ZeroMQ write error: %s(%d)", strerror(errno),
 269                  errno);
 270         if (cb->write.cb_error)
 271                 cb->write.cb_error(cb->write.arg, cb->zmqsock);
 272 }
 273
 274 int _frrzmq_thread_add_write(const struct xref_threadsched *xref,
 275                              struct thread_master *master,
 276                              void (*msgfunc)(void *arg, void *zmqsock),
 277                              void (*errfunc)(void *arg, void *zmqsock),
 278                              void *arg, void *zmqsock, struct frrzmq_cb **cbp)
 279 {
 280         int fd, events;
 281         size_t len;
 282         struct frrzmq_cb *cb;
 283
 284         if (!cbp)
 285                 return -1;
 286         if (!msgfunc)
 287                 return -1;
 288         len = sizeof(fd);
 289         if (zmq_getsockopt(zmqsock, ZMQ_FD, &fd, &len))
 290                 return -1;
 291         len = sizeof(events);
 292         if (zmq_getsockopt(zmqsock, ZMQ_EVENTS, &events, &len))
 293                 return -1;
 294
 295         if (*cbp)
 296                 cb = *cbp;
 297         else {
 298                 cb = XCALLOC(MTYPE_ZEROMQ_CB, sizeof(struct frrzmq_cb));
 299                 cb->read.cancelled = true;
 300                 *cbp = cb;
 301         }
 302
 303         cb->zmqsock = zmqsock;
 304         cb->fd = fd;
 305         cb->write.arg = arg;
 306         cb->write.cb_msg = msgfunc;
 307         cb->write.cb_part = NULL;
 308         cb->write.cb_error = errfunc;
 309         cb->write.cancelled = false;
 310         cb->in_cb = false;
 311
 312         if (events & ZMQ_POLLOUT) {
 313                 thread_cancel(&cb->write.thread);
 314
 315                 _thread_add_event(xref, master, frrzmq_write_msg, cbp, fd,
 316                                   &cb->write.thread);
 317         } else
 318                 thread_add_write(master, frrzmq_write_msg, cbp, fd,
 319                                  &cb->write.thread);
 320         return 0;
 321 }
 322
 323 void frrzmq_thread_cancel(struct frrzmq_cb **cb, struct cb_core *core)
 324 {
 325         if (!cb || !*cb)
 326                 return;
 327         core->cancelled = true;
 328         thread_cancel(&core->thread);
 329
 330         /* If cancelled from within a callback, don't try to free memory
 331          * in this path.
 332          */
 333         if ((*cb)->in_cb)
 334                 return;
 335
 336         /* Ok to free the callback context if no more ... context. */
 337         if ((*cb)->read.cancelled && !(*cb)->read.thread
 338             && (*cb)->write.cancelled && ((*cb)->write.thread == NULL))
 339                 XFREE(MTYPE_ZEROMQ_CB, *cb);
 340 }
 341
 342 void frrzmq_check_events(struct frrzmq_cb **cbp, struct cb_core *core,
 343                          int event)
 344 {
 345         struct frrzmq_cb *cb;
 346         int events;
 347         size_t len;
 348
 349         if (!cbp)
 350                 return;
 351         cb = (*cbp);
 352         if (!cb || !cb->zmqsock)
 353                 return;
 354
 355         len = sizeof(events);
 356         if (zmq_getsockopt(cb->zmqsock, ZMQ_EVENTS, &events, &len))
 357                 return;
 358         if ((events & event) && core->thread && !core->cancelled) {
 359                 struct thread_master *tm = core->thread->master;
 360
 361                 thread_cancel(&core->thread);
 362
 363                 if (event == ZMQ_POLLIN)
 364                         thread_add_event(tm, frrzmq_read_msg,
 365                                          cbp, cb->fd, &core->thread);
 366                 else
 367                         thread_add_event(tm, frrzmq_write_msg,
 368                                          cbp, cb->fd, &core->thread);
 369         }
 370 }