lib/jsonrpc.c

   1 /*
   2  * Copyright (c) 2009, 2010 Nicira Networks.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at:
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #include <config.h>
  18
  19 #include "jsonrpc.h"
  20
  21 #include <assert.h>
  22 #include <errno.h>
  23
  24 #include "byteq.h"
  25 #include "dynamic-string.h"
  26 #include "fatal-signal.h"
  27 #include "json.h"
  28 #include "list.h"
  29 #include "ofpbuf.h"
  30 #include "poll-loop.h"
  31 #include "reconnect.h"
  32 #include "stream.h"
  33 #include "timeval.h"
  34 #include "vlog.h"
  35
  36 VLOG_DEFINE_THIS_MODULE(jsonrpc);
  37 \f
  38 struct jsonrpc {
  39     struct stream *stream;
  40     char *name;
  41     int status;
  42
  43     /* Input. */
  44     struct byteq input;
  45     struct json_parser *parser;
  46     struct jsonrpc_msg *received;
  47
  48     /* Output. */
  49     struct list output;         /* Contains "struct ofpbuf"s. */
  50     size_t backlog;
  51 };
  52
  53 /* Rate limit for error messages. */
  54 static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 5);
  55
  56 static void jsonrpc_received(struct jsonrpc *);
  57 static void jsonrpc_cleanup(struct jsonrpc *);
  58
  59 /* This is just the same as stream_open() except that it uses the default
  60  * JSONRPC ports if none is specified. */
  61 int
  62 jsonrpc_stream_open(const char *name, struct stream **streamp)
  63 {
  64     return stream_open_with_default_ports(name, JSONRPC_TCP_PORT,
  65                                           JSONRPC_SSL_PORT, streamp);
  66 }
  67
  68 /* This is just the same as pstream_open() except that it uses the default
  69  * JSONRPC ports if none is specified. */
  70 int
  71 jsonrpc_pstream_open(const char *name, struct pstream **pstreamp)
  72 {
  73     return pstream_open_with_default_ports(name, JSONRPC_TCP_PORT,
  74                                            JSONRPC_SSL_PORT, pstreamp);
  75 }
  76
  77 struct jsonrpc *
  78 jsonrpc_open(struct stream *stream)
  79 {
  80     struct jsonrpc *rpc;
  81
  82     assert(stream != NULL);
  83
  84     rpc = xzalloc(sizeof *rpc);
  85     rpc->name = xstrdup(stream_get_name(stream));
  86     rpc->stream = stream;
  87     byteq_init(&rpc->input);
  88     list_init(&rpc->output);
  89
  90     return rpc;
  91 }
  92
  93 void
  94 jsonrpc_close(struct jsonrpc *rpc)
  95 {
  96     if (rpc) {
  97         jsonrpc_cleanup(rpc);
  98         free(rpc->name);
  99         free(rpc);
 100     }
 101 }
 102
 103 void
 104 jsonrpc_run(struct jsonrpc *rpc)
 105 {
 106     if (rpc->status) {
 107         return;
 108     }
 109
 110     stream_run(rpc->stream);
 111     while (!list_is_empty(&rpc->output)) {
 112         struct ofpbuf *buf = ofpbuf_from_list(rpc->output.next);
 113         int retval;
 114
 115         retval = stream_send(rpc->stream, buf->data, buf->size);
 116         if (retval >= 0) {
 117             rpc->backlog -= retval;
 118             ofpbuf_pull(buf, retval);
 119             if (!buf->size) {
 120                 list_remove(&buf->list_node);
 121                 ofpbuf_delete(buf);
 122             }
 123         } else {
 124             if (retval != -EAGAIN) {
 125                 VLOG_WARN_RL(&rl, "%s: send error: %s",
 126                              rpc->name, strerror(-retval));
 127                 jsonrpc_error(rpc, -retval);
 128             }
 129             break;
 130         }
 131     }
 132 }
 133
 134 void
 135 jsonrpc_wait(struct jsonrpc *rpc)
 136 {
 137     if (!rpc->status) {
 138         stream_run_wait(rpc->stream);
 139         if (!list_is_empty(&rpc->output)) {
 140             stream_send_wait(rpc->stream);
 141         }
 142     }
 143 }
 144
 145 /*
 146  * Possible status values:
 147  * - 0: no error yet
 148  * - >0: errno value
 149  * - EOF: end of file (remote end closed connection; not necessarily an error)
 150  */
 151 int
 152 jsonrpc_get_status(const struct jsonrpc *rpc)
 153 {
 154     return rpc->status;
 155 }
 156
 157 size_t
 158 jsonrpc_get_backlog(const struct jsonrpc *rpc)
 159 {
 160     return rpc->status ? 0 : rpc->backlog;
 161 }
 162
 163 const char *
 164 jsonrpc_get_name(const struct jsonrpc *rpc)
 165 {
 166     return rpc->name;
 167 }
 168
 169 static void
 170 jsonrpc_log_msg(const struct jsonrpc *rpc, const char *title,
 171                 const struct jsonrpc_msg *msg)
 172 {
 173     if (VLOG_IS_DBG_ENABLED()) {
 174         struct ds s = DS_EMPTY_INITIALIZER;
 175         if (msg->method) {
 176             ds_put_format(&s, ", method=\"%s\"", msg->method);
 177         }
 178         if (msg->params) {
 179             ds_put_cstr(&s, ", params=");
 180             json_to_ds(msg->params, 0, &s);
 181         }
 182         if (msg->result) {
 183             ds_put_cstr(&s, ", result=");
 184             json_to_ds(msg->result, 0, &s);
 185         }
 186         if (msg->error) {
 187             ds_put_cstr(&s, ", error=");
 188             json_to_ds(msg->error, 0, &s);
 189         }
 190         if (msg->id) {
 191             ds_put_cstr(&s, ", id=");
 192             json_to_ds(msg->id, 0, &s);
 193         }
 194         VLOG_DBG("%s: %s %s%s", rpc->name, title,
 195                  jsonrpc_msg_type_to_string(msg->type), ds_cstr(&s));
 196         ds_destroy(&s);
 197     }
 198 }
 199
 200 /* Always takes ownership of 'msg', regardless of success. */
 201 int
 202 jsonrpc_send(struct jsonrpc *rpc, struct jsonrpc_msg *msg)
 203 {
 204     struct ofpbuf *buf;
 205     struct json *json;
 206     size_t length;
 207     char *s;
 208
 209     if (rpc->status) {
 210         jsonrpc_msg_destroy(msg);
 211         return rpc->status;
 212     }
 213
 214     jsonrpc_log_msg(rpc, "send", msg);
 215
 216     json = jsonrpc_msg_to_json(msg);
 217     s = json_to_string(json, 0);
 218     length = strlen(s);
 219     json_destroy(json);
 220
 221     buf = xmalloc(sizeof *buf);
 222     ofpbuf_use(buf, s, length);
 223     buf->size = length;
 224     list_push_back(&rpc->output, &buf->list_node);
 225     rpc->backlog += length;
 226
 227     if (rpc->backlog == length) {
 228         jsonrpc_run(rpc);
 229     }
 230     return rpc->status;
 231 }
 232
 233 int
 234 jsonrpc_recv(struct jsonrpc *rpc, struct jsonrpc_msg **msgp)
 235 {
 236     *msgp = NULL;
 237     if (rpc->status) {
 238         return rpc->status;
 239     }
 240
 241     while (!rpc->received) {
 242         if (byteq_is_empty(&rpc->input)) {
 243             size_t chunk;
 244             int retval;
 245
 246             chunk = byteq_headroom(&rpc->input);
 247             retval = stream_recv(rpc->stream, byteq_head(&rpc->input), chunk);
 248             if (retval < 0) {
 249                 if (retval == -EAGAIN) {
 250                     return EAGAIN;
 251                 } else {
 252                     VLOG_WARN_RL(&rl, "%s: receive error: %s",
 253                                  rpc->name, strerror(-retval));
 254                     jsonrpc_error(rpc, -retval);
 255                     return rpc->status;
 256                 }
 257             } else if (retval == 0) {
 258                 jsonrpc_error(rpc, EOF);
 259                 return EOF;
 260             }
 261             byteq_advance_head(&rpc->input, retval);
 262         } else {
 263             size_t n, used;
 264
 265             if (!rpc->parser) {
 266                 rpc->parser = json_parser_create(0);
 267             }
 268             n = byteq_tailroom(&rpc->input);
 269             used = json_parser_feed(rpc->parser,
 270                                     (char *) byteq_tail(&rpc->input), n);
 271             byteq_advance_tail(&rpc->input, used);
 272             if (json_parser_is_done(rpc->parser)) {
 273                 jsonrpc_received(rpc);
 274                 if (rpc->status) {
 275                     const struct byteq *q = &rpc->input;
 276                     if (q->head <= BYTEQ_SIZE) {
 277                         stream_report_content(q->buffer, q->head,
 278                                               STREAM_JSONRPC,
 279                                               THIS_MODULE, rpc->name);
 280                     }
 281                     return rpc->status;
 282                 }
 283             }
 284         }
 285     }
 286
 287     *msgp = rpc->received;
 288     rpc->received = NULL;
 289     return 0;
 290 }
 291
 292 void
 293 jsonrpc_recv_wait(struct jsonrpc *rpc)
 294 {
 295     if (rpc->status || rpc->received || !byteq_is_empty(&rpc->input)) {
 296         poll_immediate_wake();
 297     } else {
 298         stream_recv_wait(rpc->stream);
 299     }
 300 }
 301
 302 /* Always takes ownership of 'msg', regardless of success. */
 303 int
 304 jsonrpc_send_block(struct jsonrpc *rpc, struct jsonrpc_msg *msg)
 305 {
 306     int error;
 307
 308     fatal_signal_run();
 309
 310     error = jsonrpc_send(rpc, msg);
 311     if (error) {
 312         return error;
 313     }
 314
 315     for (;;) {
 316         jsonrpc_run(rpc);
 317         if (list_is_empty(&rpc->output) || rpc->status) {
 318             return rpc->status;
 319         }
 320         jsonrpc_wait(rpc);
 321         poll_block();
 322     }
 323 }
 324
 325 int
 326 jsonrpc_recv_block(struct jsonrpc *rpc, struct jsonrpc_msg **msgp)
 327 {
 328     for (;;) {
 329         int error = jsonrpc_recv(rpc, msgp);
 330         if (error != EAGAIN) {
 331             fatal_signal_run();
 332             return error;
 333         }
 334
 335         jsonrpc_run(rpc);
 336         jsonrpc_wait(rpc);
 337         jsonrpc_recv_wait(rpc);
 338         poll_block();
 339     }
 340 }
 341
 342 /* Always takes ownership of 'request', regardless of success. */
 343 int
 344 jsonrpc_transact_block(struct jsonrpc *rpc, struct jsonrpc_msg *request,
 345                        struct jsonrpc_msg **replyp)
 346 {
 347     struct jsonrpc_msg *reply = NULL;
 348     struct json *id;
 349     int error;
 350
 351     id = json_clone(request->id);
 352     error = jsonrpc_send_block(rpc, request);
 353     if (!error) {
 354         for (;;) {
 355             error = jsonrpc_recv_block(rpc, &reply);
 356             if (error
 357                 || (reply->type == JSONRPC_REPLY
 358                     && json_equal(id, reply->id))) {
 359                 break;
 360             }
 361             jsonrpc_msg_destroy(reply);
 362         }
 363     }
 364     *replyp = error ? NULL : reply;
 365     json_destroy(id);
 366     return error;
 367 }
 368
 369 static void
 370 jsonrpc_received(struct jsonrpc *rpc)
 371 {
 372     struct jsonrpc_msg *msg;
 373     struct json *json;
 374     char *error;
 375
 376     json = json_parser_finish(rpc->parser);
 377     rpc->parser = NULL;
 378     if (json->type == JSON_STRING) {
 379         VLOG_WARN_RL(&rl, "%s: error parsing stream: %s",
 380                      rpc->name, json_string(json));
 381         jsonrpc_error(rpc, EPROTO);
 382         json_destroy(json);
 383         return;
 384     }
 385
 386     error = jsonrpc_msg_from_json(json, &msg);
 387     if (error) {
 388         VLOG_WARN_RL(&rl, "%s: received bad JSON-RPC message: %s",
 389                      rpc->name, error);
 390         free(error);
 391         jsonrpc_error(rpc, EPROTO);
 392         return;
 393     }
 394
 395     jsonrpc_log_msg(rpc, "received", msg);
 396     rpc->received = msg;
 397 }
 398
 399 void
 400 jsonrpc_error(struct jsonrpc *rpc, int error)
 401 {
 402     assert(error);
 403     if (!rpc->status) {
 404         rpc->status = error;
 405         jsonrpc_cleanup(rpc);
 406     }
 407 }
 408
 409 static void
 410 jsonrpc_cleanup(struct jsonrpc *rpc)
 411 {
 412     stream_close(rpc->stream);
 413     rpc->stream = NULL;
 414
 415     json_parser_abort(rpc->parser);
 416     rpc->parser = NULL;
 417
 418     jsonrpc_msg_destroy(rpc->received);
 419     rpc->received = NULL;
 420
 421     ofpbuf_list_delete(&rpc->output);
 422     rpc->backlog = 0;
 423 }
 424 \f
 425 static struct jsonrpc_msg *
 426 jsonrpc_create(enum jsonrpc_msg_type type, const char *method,
 427                 struct json *params, struct json *result, struct json *error,
 428                 struct json *id)
 429 {
 430     struct jsonrpc_msg *msg = xmalloc(sizeof *msg);
 431     msg->type = type;
 432     msg->method = method ? xstrdup(method) : NULL;
 433     msg->params = params;
 434     msg->result = result;
 435     msg->error = error;
 436     msg->id = id;
 437     return msg;
 438 }
 439
 440 static struct json *
 441 jsonrpc_create_id(void)
 442 {
 443     static unsigned int id;
 444     return json_integer_create(id++);
 445 }
 446
 447 struct jsonrpc_msg *
 448 jsonrpc_create_request(const char *method, struct json *params,
 449                        struct json **idp)
 450 {
 451     struct json *id = jsonrpc_create_id();
 452     if (idp) {
 453         *idp = json_clone(id);
 454     }
 455     return jsonrpc_create(JSONRPC_REQUEST, method, params, NULL, NULL, id);
 456 }
 457
 458 struct jsonrpc_msg *
 459 jsonrpc_create_notify(const char *method, struct json *params)
 460 {
 461     return jsonrpc_create(JSONRPC_NOTIFY, method, params, NULL, NULL, NULL);
 462 }
 463
 464 struct jsonrpc_msg *
 465 jsonrpc_create_reply(struct json *result, const struct json *id)
 466 {
 467     return jsonrpc_create(JSONRPC_REPLY, NULL, NULL, result, NULL,
 468                            json_clone(id));
 469 }
 470
 471 struct jsonrpc_msg *
 472 jsonrpc_create_error(struct json *error, const struct json *id)
 473 {
 474     return jsonrpc_create(JSONRPC_REPLY, NULL, NULL, NULL, error,
 475                            json_clone(id));
 476 }
 477
 478 const char *
 479 jsonrpc_msg_type_to_string(enum jsonrpc_msg_type type)
 480 {
 481     switch (type) {
 482     case JSONRPC_REQUEST:
 483         return "request";
 484
 485     case JSONRPC_NOTIFY:
 486         return "notification";
 487
 488     case JSONRPC_REPLY:
 489         return "reply";
 490
 491     case JSONRPC_ERROR:
 492         return "error";
 493     }
 494     return "(null)";
 495 }
 496
 497 char *
 498 jsonrpc_msg_is_valid(const struct jsonrpc_msg *m)
 499 {
 500     const char *type_name;
 501     unsigned int pattern;
 502
 503     if (m->params && m->params->type != JSON_ARRAY) {
 504         return xstrdup("\"params\" must be JSON array");
 505     }
 506
 507     switch (m->type) {
 508     case JSONRPC_REQUEST:
 509         pattern = 0x11001;
 510         break;
 511
 512     case JSONRPC_NOTIFY:
 513         pattern = 0x11000;
 514         break;
 515
 516     case JSONRPC_REPLY:
 517         pattern = 0x00101;
 518         break;
 519
 520     case JSONRPC_ERROR:
 521         pattern = 0x00011;
 522         break;
 523
 524     default:
 525         return xasprintf("invalid JSON-RPC message type %d", m->type);
 526     }
 527
 528     type_name = jsonrpc_msg_type_to_string(m->type);
 529     if ((m->method != NULL) != ((pattern & 0x10000) != 0)) {
 530         return xasprintf("%s must%s have \"method\"",
 531                          type_name, (pattern & 0x10000) ? "" : " not");
 532
 533     }
 534     if ((m->params != NULL) != ((pattern & 0x1000) != 0)) {
 535         return xasprintf("%s must%s have \"params\"",
 536                          type_name, (pattern & 0x1000) ? "" : " not");
 537
 538     }
 539     if ((m->result != NULL) != ((pattern & 0x100) != 0)) {
 540         return xasprintf("%s must%s have \"result\"",
 541                          type_name, (pattern & 0x100) ? "" : " not");
 542
 543     }
 544     if ((m->error != NULL) != ((pattern & 0x10) != 0)) {
 545         return xasprintf("%s must%s have \"error\"",
 546                          type_name, (pattern & 0x10) ? "" : " not");
 547
 548     }
 549     if ((m->id != NULL) != ((pattern & 0x1) != 0)) {
 550         return xasprintf("%s must%s have \"id\"",
 551                          type_name, (pattern & 0x1) ? "" : " not");
 552
 553     }
 554     return NULL;
 555 }
 556
 557 void
 558 jsonrpc_msg_destroy(struct jsonrpc_msg *m)
 559 {
 560     if (m) {
 561         free(m->method);
 562         json_destroy(m->params);
 563         json_destroy(m->result);
 564         json_destroy(m->error);
 565         json_destroy(m->id);
 566         free(m);
 567     }
 568 }
 569
 570 static struct json *
 571 null_from_json_null(struct json *json)
 572 {
 573     if (json && json->type == JSON_NULL) {
 574         json_destroy(json);
 575         return NULL;
 576     }
 577     return json;
 578 }
 579
 580 char *
 581 jsonrpc_msg_from_json(struct json *json, struct jsonrpc_msg **msgp)
 582 {
 583     struct json *method = NULL;
 584     struct jsonrpc_msg *msg = NULL;
 585     struct shash *object;
 586     char *error;
 587
 588     if (json->type != JSON_OBJECT) {
 589         error = xstrdup("message is not a JSON object");
 590         goto exit;
 591     }
 592     object = json_object(json);
 593
 594     method = shash_find_and_delete(object, "method");
 595     if (method && method->type != JSON_STRING) {
 596         error = xstrdup("method is not a JSON string");
 597         goto exit;
 598     }
 599
 600     msg = xzalloc(sizeof *msg);
 601     msg->method = method ? xstrdup(method->u.string) : NULL;
 602     msg->params = null_from_json_null(shash_find_and_delete(object, "params"));
 603     msg->result = null_from_json_null(shash_find_and_delete(object, "result"));
 604     msg->error = null_from_json_null(shash_find_and_delete(object, "error"));
 605     msg->id = null_from_json_null(shash_find_and_delete(object, "id"));
 606     msg->type = (msg->result ? JSONRPC_REPLY
 607                  : msg->error ? JSONRPC_ERROR
 608                  : msg->id ? JSONRPC_REQUEST
 609                  : JSONRPC_NOTIFY);
 610     if (!shash_is_empty(object)) {
 611         error = xasprintf("message has unexpected member \"%s\"",
 612                           shash_first(object)->name);
 613         goto exit;
 614     }
 615     error = jsonrpc_msg_is_valid(msg);
 616     if (error) {
 617         goto exit;
 618     }
 619
 620 exit:
 621     json_destroy(method);
 622     json_destroy(json);
 623     if (error) {
 624         jsonrpc_msg_destroy(msg);
 625         msg = NULL;
 626     }
 627     *msgp = msg;
 628     return error;
 629 }
 630
 631 struct json *
 632 jsonrpc_msg_to_json(struct jsonrpc_msg *m)
 633 {
 634     struct json *json = json_object_create();
 635
 636     if (m->method) {
 637         json_object_put(json, "method", json_string_create_nocopy(m->method));
 638     }
 639
 640     if (m->params) {
 641         json_object_put(json, "params", m->params);
 642     }
 643
 644     if (m->result) {
 645         json_object_put(json, "result", m->result);
 646     } else if (m->type == JSONRPC_ERROR) {
 647         json_object_put(json, "result", json_null_create());
 648     }
 649
 650     if (m->error) {
 651         json_object_put(json, "error", m->error);
 652     } else if (m->type == JSONRPC_REPLY) {
 653         json_object_put(json, "error", json_null_create());
 654     }
 655
 656     if (m->id) {
 657         json_object_put(json, "id", m->id);
 658     } else if (m->type == JSONRPC_NOTIFY) {
 659         json_object_put(json, "id", json_null_create());
 660     }
 661
 662     free(m);
 663
 664     return json;
 665 }
 666 \f
 667 /* A JSON-RPC session with reconnection. */
 668
 669 struct jsonrpc_session {
 670     struct reconnect *reconnect;
 671     struct jsonrpc *rpc;
 672     struct stream *stream;
 673     struct pstream *pstream;
 674     unsigned int seqno;
 675 };
 676
 677 /* Creates and returns a jsonrpc_session to 'name', which should be a string
 678  * acceptable to stream_open() or pstream_open().
 679  *
 680  * If 'name' is an active connection method, e.g. "tcp:127.1.2.3", the new
 681  * jsonrpc_session connects and reconnects, with back-off, to 'name'.
 682  *
 683  * If 'name' is a passive connection method, e.g. "ptcp:", the new
 684  * jsonrpc_session listens for connections to 'name'.  It maintains at most one
 685  * connection at any given time.  Any new connection causes the previous one
 686  * (if any) to be dropped. */
 687 struct jsonrpc_session *
 688 jsonrpc_session_open(const char *name)
 689 {
 690     struct jsonrpc_session *s;
 691
 692     s = xmalloc(sizeof *s);
 693     s->reconnect = reconnect_create(time_msec());
 694     reconnect_set_name(s->reconnect, name);
 695     reconnect_enable(s->reconnect, time_msec());
 696     s->rpc = NULL;
 697     s->stream = NULL;
 698     s->pstream = NULL;
 699     s->seqno = 0;
 700
 701     if (!pstream_verify_name(name)) {
 702         reconnect_set_passive(s->reconnect, true, time_msec());
 703     }
 704
 705     return s;
 706 }
 707
 708 /* Creates and returns a jsonrpc_session that is initially connected to
 709  * 'jsonrpc'.  If the connection is dropped, it will not be reconnected.
 710  *
 711  * On the assumption that such connections are likely to be short-lived
 712  * (e.g. from ovs-vsctl), informational logging for them is suppressed. */
 713 struct jsonrpc_session *
 714 jsonrpc_session_open_unreliably(struct jsonrpc *jsonrpc)
 715 {
 716     struct jsonrpc_session *s;
 717
 718     s = xmalloc(sizeof *s);
 719     s->reconnect = reconnect_create(time_msec());
 720     reconnect_set_quiet(s->reconnect, true);
 721     reconnect_set_name(s->reconnect, jsonrpc_get_name(jsonrpc));
 722     reconnect_set_max_tries(s->reconnect, 0);
 723     reconnect_connected(s->reconnect, time_msec());
 724     s->rpc = jsonrpc;
 725     s->stream = NULL;
 726     s->pstream = NULL;
 727     s->seqno = 0;
 728
 729     return s;
 730 }
 731
 732 void
 733 jsonrpc_session_close(struct jsonrpc_session *s)
 734 {
 735     if (s) {
 736         jsonrpc_close(s->rpc);
 737         reconnect_destroy(s->reconnect);
 738         stream_close(s->stream);
 739         pstream_close(s->pstream);
 740         free(s);
 741     }
 742 }
 743
 744 static void
 745 jsonrpc_session_disconnect(struct jsonrpc_session *s)
 746 {
 747     if (s->rpc) {
 748         jsonrpc_error(s->rpc, EOF);
 749         jsonrpc_close(s->rpc);
 750         s->rpc = NULL;
 751         s->seqno++;
 752     } else if (s->stream) {
 753         stream_close(s->stream);
 754         s->stream = NULL;
 755         s->seqno++;
 756     }
 757 }
 758
 759 static void
 760 jsonrpc_session_connect(struct jsonrpc_session *s)
 761 {
 762     const char *name = reconnect_get_name(s->reconnect);
 763     int error;
 764
 765     jsonrpc_session_disconnect(s);
 766     if (!reconnect_is_passive(s->reconnect)) {
 767         error = jsonrpc_stream_open(name, &s->stream);
 768         if (!error) {
 769             reconnect_connecting(s->reconnect, time_msec());
 770         }
 771     } else {
 772         error = s->pstream ? 0 : jsonrpc_pstream_open(name, &s->pstream);
 773         if (!error) {
 774             reconnect_listening(s->reconnect, time_msec());
 775         }
 776     }
 777
 778     if (error) {
 779         reconnect_connect_failed(s->reconnect, time_msec(), error);
 780     }
 781     s->seqno++;
 782 }
 783
 784 void
 785 jsonrpc_session_run(struct jsonrpc_session *s)
 786 {
 787     if (s->pstream) {
 788         struct stream *stream;
 789         int error;
 790
 791         error = pstream_accept(s->pstream, &stream);
 792         if (!error) {
 793             if (s->rpc || s->stream) {
 794                 VLOG_INFO_RL(&rl,
 795                              "%s: new connection replacing active connection",
 796                              reconnect_get_name(s->reconnect));
 797                 jsonrpc_session_disconnect(s);
 798             }
 799             reconnect_connected(s->reconnect, time_msec());
 800             s->rpc = jsonrpc_open(stream);
 801         } else if (error != EAGAIN) {
 802             reconnect_listen_error(s->reconnect, time_msec(), error);
 803             pstream_close(s->pstream);
 804             s->pstream = NULL;
 805         }
 806     }
 807
 808     if (s->rpc) {
 809         int error;
 810
 811         jsonrpc_run(s->rpc);
 812         error = jsonrpc_get_status(s->rpc);
 813         if (error) {
 814             reconnect_disconnected(s->reconnect, time_msec(), error);
 815             jsonrpc_session_disconnect(s);
 816         }
 817     } else if (s->stream) {
 818         int error;
 819
 820         stream_run(s->stream);
 821         error = stream_connect(s->stream);
 822         if (!error) {
 823             reconnect_connected(s->reconnect, time_msec());
 824             s->rpc = jsonrpc_open(s->stream);
 825             s->stream = NULL;
 826         } else if (error != EAGAIN) {
 827             reconnect_connect_failed(s->reconnect, time_msec(), error);
 828             stream_close(s->stream);
 829             s->stream = NULL;
 830         }
 831     }
 832
 833     switch (reconnect_run(s->reconnect, time_msec())) {
 834     case RECONNECT_CONNECT:
 835         jsonrpc_session_connect(s);
 836         break;
 837
 838     case RECONNECT_DISCONNECT:
 839         reconnect_disconnected(s->reconnect, time_msec(), 0);
 840         jsonrpc_session_disconnect(s);
 841         break;
 842
 843     case RECONNECT_PROBE:
 844         if (s->rpc) {
 845             struct json *params;
 846             struct jsonrpc_msg *request;
 847
 848             params = json_array_create_empty();
 849             request = jsonrpc_create_request("echo", params, NULL);
 850             json_destroy(request->id);
 851             request->id = json_string_create("echo");
 852             jsonrpc_send(s->rpc, request);
 853         }
 854         break;
 855     }
 856 }
 857
 858 void
 859 jsonrpc_session_wait(struct jsonrpc_session *s)
 860 {
 861     if (s->rpc) {
 862         jsonrpc_wait(s->rpc);
 863     } else if (s->stream) {
 864         stream_run_wait(s->stream);
 865         stream_connect_wait(s->stream);
 866     }
 867     if (s->pstream) {
 868         pstream_wait(s->pstream);
 869     }
 870     reconnect_wait(s->reconnect, time_msec());
 871 }
 872
 873 size_t
 874 jsonrpc_session_get_backlog(const struct jsonrpc_session *s)
 875 {
 876     return s->rpc ? jsonrpc_get_backlog(s->rpc) : 0;
 877 }
 878
 879 const char *
 880 jsonrpc_session_get_name(const struct jsonrpc_session *s)
 881 {
 882     return reconnect_get_name(s->reconnect);
 883 }
 884
 885 /* Always takes ownership of 'msg', regardless of success. */
 886 int
 887 jsonrpc_session_send(struct jsonrpc_session *s, struct jsonrpc_msg *msg)
 888 {
 889     if (s->rpc) {
 890         return jsonrpc_send(s->rpc, msg);
 891     } else {
 892         jsonrpc_msg_destroy(msg);
 893         return ENOTCONN;
 894     }
 895 }
 896
 897 struct jsonrpc_msg *
 898 jsonrpc_session_recv(struct jsonrpc_session *s)
 899 {
 900     if (s->rpc) {
 901         struct jsonrpc_msg *msg;
 902         jsonrpc_recv(s->rpc, &msg);
 903         if (msg) {
 904             reconnect_received(s->reconnect, time_msec());
 905             if (msg->type == JSONRPC_REQUEST && !strcmp(msg->method, "echo")) {
 906                 /* Echo request.  Send reply. */
 907                 struct jsonrpc_msg *reply;
 908
 909                 reply = jsonrpc_create_reply(json_clone(msg->params), msg->id);
 910                 jsonrpc_session_send(s, reply);
 911             } else if (msg->type == JSONRPC_REPLY
 912                        && msg->id && msg->id->type == JSON_STRING
 913                        && !strcmp(msg->id->u.string, "echo")) {
 914                 /* It's a reply to our echo request.  Suppress it. */
 915             } else {
 916                 return msg;
 917             }
 918             jsonrpc_msg_destroy(msg);
 919         }
 920     }
 921     return NULL;
 922 }
 923
 924 void
 925 jsonrpc_session_recv_wait(struct jsonrpc_session *s)
 926 {
 927     if (s->rpc) {
 928         jsonrpc_recv_wait(s->rpc);
 929     }
 930 }
 931
 932 bool
 933 jsonrpc_session_is_alive(const struct jsonrpc_session *s)
 934 {
 935     return s->rpc || s->stream || reconnect_get_max_tries(s->reconnect);
 936 }
 937
 938 bool
 939 jsonrpc_session_is_connected(const struct jsonrpc_session *s)
 940 {
 941     return s->rpc != NULL;
 942 }
 943
 944 unsigned int
 945 jsonrpc_session_get_seqno(const struct jsonrpc_session *s)
 946 {
 947     return s->seqno;
 948 }
 949
 950 void
 951 jsonrpc_session_force_reconnect(struct jsonrpc_session *s)
 952 {
 953     reconnect_force_reconnect(s->reconnect, time_msec());
 954 }
 955
 956 void
 957 jsonrpc_session_set_max_backoff(struct jsonrpc_session *s, int max_backoff)
 958 {
 959     reconnect_set_backoff(s->reconnect, 0, max_backoff);
 960 }
 961
 962 void
 963 jsonrpc_session_set_probe_interval(struct jsonrpc_session *s,
 964                                    int probe_interval)
 965 {
 966     reconnect_set_probe_interval(s->reconnect, probe_interval);
 967 }