lib/frr_zmq.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * libzebra ZeroMQ bindings
   4  * Copyright (C) 2015  David Lamparter
   5  */
   6
   7 /*
   8  * IF YOU MODIFY THIS FILE PLEASE RUN `make check` and ensure that
   9  * the test_zmq.c unit test is still working.  There are dependencies
  10  * between the two that are extremely fragile.  My understanding
  11  * is that there is specialized ownership of the cb pointer based
  12  * upon what is happening.  Those assumptions are supposed to be
  13  * tested in the test_zmq.c
  14  */
  15 #include <zebra.h>
  16 #include <zmq.h>
  17
  18 #include "event.h"
  19 #include "memory.h"
  20 #include "frr_zmq.h"
  21 #include "log.h"
  22 #include "lib_errors.h"
  23
  24 DEFINE_MTYPE_STATIC(LIB, ZEROMQ_CB, "ZeroMQ callback");
  25
  26 /* libzmq's context */
  27 void *frrzmq_context = NULL;
  28 static unsigned frrzmq_initcount = 0;
  29
  30 void frrzmq_init(void)
  31 {
  32         if (frrzmq_initcount++ == 0) {
  33                 frrzmq_context = zmq_ctx_new();
  34                 zmq_ctx_set(frrzmq_context, ZMQ_IPV6, 1);
  35         }
  36 }
  37
  38 void frrzmq_finish(void)
  39 {
  40         if (--frrzmq_initcount == 0) {
  41                 zmq_ctx_term(frrzmq_context);
  42                 frrzmq_context = NULL;
  43         }
  44 }
  45
  46 static void frrzmq_read_msg(struct event *t)
  47 {
  48         struct frrzmq_cb **cbp = THREAD_ARG(t);
  49         struct frrzmq_cb *cb;
  50         zmq_msg_t msg;
  51         unsigned partno;
  52         unsigned char read = 0;
  53         int ret, more;
  54         size_t moresz;
  55
  56         if (!cbp)
  57                 return;
  58         cb = (*cbp);
  59         if (!cb || !cb->zmqsock)
  60                 return;
  61
  62         while (1) {
  63                 zmq_pollitem_t polli = {.socket = cb->zmqsock,
  64                                         .events = ZMQ_POLLIN};
  65                 ret = zmq_poll(&polli, 1, 0);
  66
  67                 if (ret < 0)
  68                         goto out_err;
  69
  70                 if (!(polli.revents & ZMQ_POLLIN))
  71                         break;
  72
  73                 if (cb->read.cb_msg) {
  74                         cb->in_cb = true;
  75                         cb->read.cb_msg(cb->read.arg, cb->zmqsock);
  76                         cb->in_cb = false;
  77
  78                         read = 1;
  79
  80                         if (cb->read.cancelled) {
  81                                 frrzmq_check_events(cbp, &cb->write,
  82                                                     ZMQ_POLLOUT);
  83                                 cb->read.thread = NULL;
  84                                 if (cb->write.cancelled && !cb->write.thread)
  85                                         XFREE(MTYPE_ZEROMQ_CB, *cbp);
  86
  87                                 return;
  88                         }
  89                         continue;
  90                 }
  91
  92                 partno = 0;
  93                 if (zmq_msg_init(&msg))
  94                         goto out_err;
  95                 do {
  96                         ret = zmq_msg_recv(&msg, cb->zmqsock, ZMQ_NOBLOCK);
  97                         if (ret < 0) {
  98                                 if (errno == EAGAIN)
  99                                         break;
 100
 101                                 zmq_msg_close(&msg);
 102                                 goto out_err;
 103                         }
 104                         read = 1;
 105
 106                         cb->in_cb = true;
 107                         cb->read.cb_part(cb->read.arg, cb->zmqsock, &msg,
 108                                          partno);
 109                         cb->in_cb = false;
 110
 111                         if (cb->read.cancelled) {
 112                                 zmq_msg_close(&msg);
 113                                 frrzmq_check_events(cbp, &cb->write,
 114                                                     ZMQ_POLLOUT);
 115                                 cb->read.thread = NULL;
 116                                 if (cb->write.cancelled && !cb->write.thread)
 117                                         XFREE(MTYPE_ZEROMQ_CB, *cbp);
 118
 119                                 return;
 120                         }
 121
 122                         /* cb_part may have read additional parts of the
 123                          * message; don't use zmq_msg_more here */
 124                         moresz = sizeof(more);
 125                         more = 0;
 126                         ret = zmq_getsockopt(cb->zmqsock, ZMQ_RCVMORE, &more,
 127                                              &moresz);
 128                         if (ret < 0) {
 129                                 zmq_msg_close(&msg);
 130                                 goto out_err;
 131                         }
 132
 133                         partno++;
 134                 } while (more);
 135                 zmq_msg_close(&msg);
 136         }
 137
 138         if (read)
 139                 frrzmq_check_events(cbp, &cb->write, ZMQ_POLLOUT);
 140
 141         event_add_read(t->master, frrzmq_read_msg, cbp, cb->fd,
 142                        &cb->read.thread);
 143         return;
 144
 145 out_err:
 146         flog_err(EC_LIB_ZMQ, "ZeroMQ read error: %s(%d)", strerror(errno),
 147                  errno);
 148         if (cb->read.cb_error)
 149                 cb->read.cb_error(cb->read.arg, cb->zmqsock);
 150 }
 151
 152 int _frrzmq_event_add_read(const struct xref_threadsched *xref,
 153                            struct thread_master *master,
 154                            void (*msgfunc)(void *arg, void *zmqsock),
 155                            void (*partfunc)(void *arg, void *zmqsock,
 156                                             zmq_msg_t *msg, unsigned partnum),
 157                            void (*errfunc)(void *arg, void *zmqsock), void *arg,
 158                            void *zmqsock, struct frrzmq_cb **cbp)
 159 {
 160         int fd, events;
 161         size_t len;
 162         struct frrzmq_cb *cb;
 163
 164         if (!cbp)
 165                 return -1;
 166         if (!(msgfunc || partfunc) || (msgfunc && partfunc))
 167                 return -1;
 168         len = sizeof(fd);
 169         if (zmq_getsockopt(zmqsock, ZMQ_FD, &fd, &len))
 170                 return -1;
 171         len = sizeof(events);
 172         if (zmq_getsockopt(zmqsock, ZMQ_EVENTS, &events, &len))
 173                 return -1;
 174
 175         if (*cbp)
 176                 cb = *cbp;
 177         else {
 178                 cb = XCALLOC(MTYPE_ZEROMQ_CB, sizeof(struct frrzmq_cb));
 179                 cb->write.cancelled = true;
 180                 *cbp = cb;
 181         }
 182
 183         cb->zmqsock = zmqsock;
 184         cb->fd = fd;
 185         cb->read.arg = arg;
 186         cb->read.cb_msg = msgfunc;
 187         cb->read.cb_part = partfunc;
 188         cb->read.cb_error = errfunc;
 189         cb->read.cancelled = false;
 190         cb->in_cb = false;
 191
 192         if (events & ZMQ_POLLIN) {
 193                 event_cancel(&cb->read.thread);
 194
 195                 event_add_event(master, frrzmq_read_msg, cbp, fd,
 196                                 &cb->read.thread);
 197         } else
 198                 event_add_read(master, frrzmq_read_msg, cbp, fd,
 199                                &cb->read.thread);
 200         return 0;
 201 }
 202
 203 static void frrzmq_write_msg(struct event *t)
 204 {
 205         struct frrzmq_cb **cbp = THREAD_ARG(t);
 206         struct frrzmq_cb *cb;
 207         unsigned char written = 0;
 208         int ret;
 209
 210         if (!cbp)
 211                 return;
 212         cb = (*cbp);
 213         if (!cb || !cb->zmqsock)
 214                 return;
 215
 216         while (1) {
 217                 zmq_pollitem_t polli = {.socket = cb->zmqsock,
 218                                         .events = ZMQ_POLLOUT};
 219                 ret = zmq_poll(&polli, 1, 0);
 220
 221                 if (ret < 0)
 222                         goto out_err;
 223
 224                 if (!(polli.revents & ZMQ_POLLOUT))
 225                         break;
 226
 227                 if (cb->write.cb_msg) {
 228                         cb->in_cb = true;
 229                         cb->write.cb_msg(cb->write.arg, cb->zmqsock);
 230                         cb->in_cb = false;
 231
 232                         written = 1;
 233
 234                         if (cb->write.cancelled) {
 235                                 frrzmq_check_events(cbp, &cb->read, ZMQ_POLLIN);
 236                                 cb->write.thread = NULL;
 237                                 if (cb->read.cancelled && !cb->read.thread)
 238                                         XFREE(MTYPE_ZEROMQ_CB, *cbp);
 239
 240                                 return;
 241                         }
 242                         continue;
 243                 }
 244         }
 245
 246         if (written)
 247                 frrzmq_check_events(cbp, &cb->read, ZMQ_POLLIN);
 248
 249         event_add_write(t->master, frrzmq_write_msg, cbp, cb->fd,
 250                         &cb->write.thread);
 251         return;
 252
 253 out_err:
 254         flog_err(EC_LIB_ZMQ, "ZeroMQ write error: %s(%d)", strerror(errno),
 255                  errno);
 256         if (cb->write.cb_error)
 257                 cb->write.cb_error(cb->write.arg, cb->zmqsock);
 258 }
 259
 260 int _frrzmq_event_add_write(const struct xref_threadsched *xref,
 261                             struct thread_master *master,
 262                             void (*msgfunc)(void *arg, void *zmqsock),
 263                             void (*errfunc)(void *arg, void *zmqsock),
 264                             void *arg, void *zmqsock, struct frrzmq_cb **cbp)
 265 {
 266         int fd, events;
 267         size_t len;
 268         struct frrzmq_cb *cb;
 269
 270         if (!cbp)
 271                 return -1;
 272         if (!msgfunc)
 273                 return -1;
 274         len = sizeof(fd);
 275         if (zmq_getsockopt(zmqsock, ZMQ_FD, &fd, &len))
 276                 return -1;
 277         len = sizeof(events);
 278         if (zmq_getsockopt(zmqsock, ZMQ_EVENTS, &events, &len))
 279                 return -1;
 280
 281         if (*cbp)
 282                 cb = *cbp;
 283         else {
 284                 cb = XCALLOC(MTYPE_ZEROMQ_CB, sizeof(struct frrzmq_cb));
 285                 cb->read.cancelled = true;
 286                 *cbp = cb;
 287         }
 288
 289         cb->zmqsock = zmqsock;
 290         cb->fd = fd;
 291         cb->write.arg = arg;
 292         cb->write.cb_msg = msgfunc;
 293         cb->write.cb_part = NULL;
 294         cb->write.cb_error = errfunc;
 295         cb->write.cancelled = false;
 296         cb->in_cb = false;
 297
 298         if (events & ZMQ_POLLOUT) {
 299                 event_cancel(&cb->write.thread);
 300
 301                 _event_add_event(xref, master, frrzmq_write_msg, cbp, fd,
 302                                  &cb->write.thread);
 303         } else
 304                 event_add_write(master, frrzmq_write_msg, cbp, fd,
 305                                 &cb->write.thread);
 306         return 0;
 307 }
 308
 309 void frrzmq_thread_cancel(struct frrzmq_cb **cb, struct cb_core *core)
 310 {
 311         if (!cb || !*cb)
 312                 return;
 313         core->cancelled = true;
 314         event_cancel(&core->thread);
 315
 316         /* If cancelled from within a callback, don't try to free memory
 317          * in this path.
 318          */
 319         if ((*cb)->in_cb)
 320                 return;
 321
 322         /* Ok to free the callback context if no more ... context. */
 323         if ((*cb)->read.cancelled && !(*cb)->read.thread
 324             && (*cb)->write.cancelled && ((*cb)->write.thread == NULL))
 325                 XFREE(MTYPE_ZEROMQ_CB, *cb);
 326 }
 327
 328 void frrzmq_check_events(struct frrzmq_cb **cbp, struct cb_core *core,
 329                          int event)
 330 {
 331         struct frrzmq_cb *cb;
 332         int events;
 333         size_t len;
 334
 335         if (!cbp)
 336                 return;
 337         cb = (*cbp);
 338         if (!cb || !cb->zmqsock)
 339                 return;
 340
 341         len = sizeof(events);
 342         if (zmq_getsockopt(cb->zmqsock, ZMQ_EVENTS, &events, &len))
 343                 return;
 344         if ((events & event) && core->thread && !core->cancelled) {
 345                 struct thread_master *tm = core->thread->master;
 346
 347                 event_cancel(&core->thread);
 348
 349                 if (event == ZMQ_POLLIN)
 350                         event_add_event(tm, frrzmq_read_msg, cbp, cb->fd,
 351                                         &core->thread);
 352                 else
 353                         event_add_event(tm, frrzmq_write_msg, cbp, cb->fd,
 354                                         &core->thread);
 355         }
 356 }