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 "json.h"
  27 #include "list.h"
  28 #include "ofpbuf.h"
  29 #include "poll-loop.h"
  30 #include "queue.h"
  31 #include "reconnect.h"
  32 #include "stream.h"
  33 #include "timeval.h"
  34
  35 #define THIS_MODULE VLM_jsonrpc
  36 #include "vlog.h"
  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 ovs_queue output;
  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 struct jsonrpc *
  60 jsonrpc_open(struct stream *stream)
  61 {
  62     struct jsonrpc *rpc;
  63
  64     assert(stream != NULL);
  65
  66     rpc = xzalloc(sizeof *rpc);
  67     rpc->name = xstrdup(stream_get_name(stream));
  68     rpc->stream = stream;
  69     byteq_init(&rpc->input);
  70     queue_init(&rpc->output);
  71
  72     return rpc;
  73 }
  74
  75 void
  76 jsonrpc_close(struct jsonrpc *rpc)
  77 {
  78     if (rpc) {
  79         jsonrpc_cleanup(rpc);
  80         free(rpc->name);
  81         free(rpc);
  82     }
  83 }
  84
  85 void
  86 jsonrpc_run(struct jsonrpc *rpc)
  87 {
  88     if (rpc->status) {
  89         return;
  90     }
  91
  92     stream_run(rpc->stream);
  93     while (!queue_is_empty(&rpc->output)) {
  94         struct ofpbuf *buf = rpc->output.head;
  95         int retval;
  96
  97         retval = stream_send(rpc->stream, buf->data, buf->size);
  98         if (retval >= 0) {
  99             rpc->backlog -= retval;
 100             ofpbuf_pull(buf, retval);
 101             if (!buf->size) {
 102                 ofpbuf_delete(queue_pop_head(&rpc->output));
 103             }
 104         } else {
 105             if (retval != -EAGAIN) {
 106                 VLOG_WARN_RL(&rl, "%s: send error: %s",
 107                              rpc->name, strerror(-retval));
 108                 jsonrpc_error(rpc, -retval);
 109             }
 110             break;
 111         }
 112     }
 113 }
 114
 115 void
 116 jsonrpc_wait(struct jsonrpc *rpc)
 117 {
 118     if (!rpc->status) {
 119         stream_run_wait(rpc->stream);
 120         if (!queue_is_empty(&rpc->output)) {
 121             stream_send_wait(rpc->stream);
 122         }
 123     }
 124 }
 125
 126 int
 127 jsonrpc_get_status(const struct jsonrpc *rpc)
 128 {
 129     return rpc->status;
 130 }
 131
 132 size_t
 133 jsonrpc_get_backlog(const struct jsonrpc *rpc)
 134 {
 135     return rpc->status ? 0 : rpc->backlog;
 136 }
 137
 138 const char *
 139 jsonrpc_get_name(const struct jsonrpc *rpc)
 140 {
 141     return rpc->name;
 142 }
 143
 144 static void
 145 jsonrpc_log_msg(const struct jsonrpc *rpc, const char *title,
 146                 const struct jsonrpc_msg *msg)
 147 {
 148     if (VLOG_IS_DBG_ENABLED()) {
 149         struct ds s = DS_EMPTY_INITIALIZER;
 150         if (msg->method) {
 151             ds_put_format(&s, ", method=\"%s\"", msg->method);
 152         }
 153         if (msg->params) {
 154             ds_put_cstr(&s, ", params=");
 155             json_to_ds(msg->params, 0, &s);
 156         }
 157         if (msg->result) {
 158             ds_put_cstr(&s, ", result=");
 159             json_to_ds(msg->result, 0, &s);
 160         }
 161         if (msg->error) {
 162             ds_put_cstr(&s, ", error=");
 163             json_to_ds(msg->error, 0, &s);
 164         }
 165         if (msg->id) {
 166             ds_put_cstr(&s, ", id=");
 167             json_to_ds(msg->id, 0, &s);
 168         }
 169         VLOG_DBG("%s: %s %s%s", rpc->name, title,
 170                  jsonrpc_msg_type_to_string(msg->type), ds_cstr(&s));
 171         ds_destroy(&s);
 172     }
 173 }
 174
 175 /* Always takes ownership of 'msg', regardless of success. */
 176 int
 177 jsonrpc_send(struct jsonrpc *rpc, struct jsonrpc_msg *msg)
 178 {
 179     struct ofpbuf *buf;
 180     struct json *json;
 181     size_t length;
 182     char *s;
 183
 184     if (rpc->status) {
 185         jsonrpc_msg_destroy(msg);
 186         return rpc->status;
 187     }
 188
 189     jsonrpc_log_msg(rpc, "send", msg);
 190
 191     json = jsonrpc_msg_to_json(msg);
 192     s = json_to_string(json, 0);
 193     length = strlen(s);
 194     json_destroy(json);
 195
 196     buf = xmalloc(sizeof *buf);
 197     ofpbuf_use(buf, s, length);
 198     buf->size = length;
 199     queue_push_tail(&rpc->output, buf);
 200     rpc->backlog += length;
 201
 202     if (rpc->output.n == 1) {
 203         jsonrpc_run(rpc);
 204     }
 205     return rpc->status;
 206 }
 207
 208 int
 209 jsonrpc_recv(struct jsonrpc *rpc, struct jsonrpc_msg **msgp)
 210 {
 211     *msgp = NULL;
 212     if (rpc->status) {
 213         return rpc->status;
 214     }
 215
 216     while (!rpc->received) {
 217         if (byteq_is_empty(&rpc->input)) {
 218             size_t chunk;
 219             int retval;
 220
 221             chunk = byteq_headroom(&rpc->input);
 222             retval = stream_recv(rpc->stream, byteq_head(&rpc->input), chunk);
 223             if (retval < 0) {
 224                 if (retval == -EAGAIN) {
 225                     return EAGAIN;
 226                 } else {
 227                     VLOG_WARN_RL(&rl, "%s: receive error: %s",
 228                                  rpc->name, strerror(-retval));
 229                     jsonrpc_error(rpc, -retval);
 230                     return rpc->status;
 231                 }
 232             } else if (retval == 0) {
 233                 VLOG_INFO_RL(&rl, "%s: connection closed", rpc->name);
 234                 jsonrpc_error(rpc, EOF);
 235                 return EOF;
 236             }
 237             byteq_advance_head(&rpc->input, retval);
 238         } else {
 239             size_t n, used;
 240
 241             if (!rpc->parser) {
 242                 rpc->parser = json_parser_create(0);
 243             }
 244             n = byteq_tailroom(&rpc->input);
 245             used = json_parser_feed(rpc->parser,
 246                                     (char *) byteq_tail(&rpc->input), n);
 247             byteq_advance_tail(&rpc->input, used);
 248             if (json_parser_is_done(rpc->parser)) {
 249                 jsonrpc_received(rpc);
 250                 if (rpc->status) {
 251                     return rpc->status;
 252                 }
 253             }
 254         }
 255     }
 256
 257     *msgp = rpc->received;
 258     rpc->received = NULL;
 259     return 0;
 260 }
 261
 262 void
 263 jsonrpc_recv_wait(struct jsonrpc *rpc)
 264 {
 265     if (rpc->status || rpc->received || !byteq_is_empty(&rpc->input)) {
 266         poll_immediate_wake();
 267     } else {
 268         stream_recv_wait(rpc->stream);
 269     }
 270 }
 271
 272 /* Always takes ownership of 'msg', regardless of success. */
 273 int
 274 jsonrpc_send_block(struct jsonrpc *rpc, struct jsonrpc_msg *msg)
 275 {
 276     int error;
 277
 278     error = jsonrpc_send(rpc, msg);
 279     if (error) {
 280         return error;
 281     }
 282
 283     for (;;) {
 284         jsonrpc_run(rpc);
 285         if (queue_is_empty(&rpc->output) || rpc->status) {
 286             return rpc->status;
 287         }
 288         jsonrpc_wait(rpc);
 289         poll_block();
 290     }
 291 }
 292
 293 int
 294 jsonrpc_recv_block(struct jsonrpc *rpc, struct jsonrpc_msg **msgp)
 295 {
 296     for (;;) {
 297         int error = jsonrpc_recv(rpc, msgp);
 298         if (error != EAGAIN) {
 299             return error;
 300         }
 301
 302         jsonrpc_run(rpc);
 303         jsonrpc_wait(rpc);
 304         jsonrpc_recv_wait(rpc);
 305         poll_block();
 306     }
 307 }
 308
 309 /* Always takes ownership of 'request', regardless of success. */
 310 int
 311 jsonrpc_transact_block(struct jsonrpc *rpc, struct jsonrpc_msg *request,
 312                        struct jsonrpc_msg **replyp)
 313 {
 314     struct jsonrpc_msg *reply = NULL;
 315     struct json *id;
 316     int error;
 317
 318     id = json_clone(request->id);
 319     error = jsonrpc_send_block(rpc, request);
 320     if (!error) {
 321         for (;;) {
 322             error = jsonrpc_recv_block(rpc, &reply);
 323             if (error
 324                 || (reply->type == JSONRPC_REPLY
 325                     && json_equal(id, reply->id))) {
 326                 break;
 327             }
 328             jsonrpc_msg_destroy(reply);
 329         }
 330     }
 331     *replyp = error ? NULL : reply;
 332     json_destroy(id);
 333     return error;
 334 }
 335
 336 static void
 337 jsonrpc_received(struct jsonrpc *rpc)
 338 {
 339     struct jsonrpc_msg *msg;
 340     struct json *json;
 341     char *error;
 342
 343     json = json_parser_finish(rpc->parser);
 344     rpc->parser = NULL;
 345     if (json->type == JSON_STRING) {
 346         VLOG_WARN_RL(&rl, "%s: error parsing stream: %s",
 347                      rpc->name, json_string(json));
 348         jsonrpc_error(rpc, EPROTO);
 349         json_destroy(json);
 350         return;
 351     }
 352
 353     error = jsonrpc_msg_from_json(json, &msg);
 354     if (error) {
 355         VLOG_WARN_RL(&rl, "%s: received bad JSON-RPC message: %s",
 356                      rpc->name, error);
 357         free(error);
 358         jsonrpc_error(rpc, EPROTO);
 359         return;
 360     }
 361
 362     jsonrpc_log_msg(rpc, "received", msg);
 363     rpc->received = msg;
 364 }
 365
 366 void
 367 jsonrpc_error(struct jsonrpc *rpc, int error)
 368 {
 369     assert(error);
 370     if (!rpc->status) {
 371         rpc->status = error;
 372         jsonrpc_cleanup(rpc);
 373     }
 374 }
 375
 376 static void
 377 jsonrpc_cleanup(struct jsonrpc *rpc)
 378 {
 379     stream_close(rpc->stream);
 380     rpc->stream = NULL;
 381
 382     json_parser_abort(rpc->parser);
 383     rpc->parser = NULL;
 384
 385     jsonrpc_msg_destroy(rpc->received);
 386     rpc->received = NULL;
 387
 388     queue_clear(&rpc->output);
 389     rpc->backlog = 0;
 390 }
 391 \f
 392 static struct jsonrpc_msg *
 393 jsonrpc_create(enum jsonrpc_msg_type type, const char *method,
 394                 struct json *params, struct json *result, struct json *error,
 395                 struct json *id)
 396 {
 397     struct jsonrpc_msg *msg = xmalloc(sizeof *msg);
 398     msg->type = type;
 399     msg->method = method ? xstrdup(method) : NULL;
 400     msg->params = params;
 401     msg->result = result;
 402     msg->error = error;
 403     msg->id = id;
 404     return msg;
 405 }
 406
 407 static struct json *
 408 jsonrpc_create_id(void)
 409 {
 410     static unsigned int id;
 411     return json_integer_create(id++);
 412 }
 413
 414 struct jsonrpc_msg *
 415 jsonrpc_create_request(const char *method, struct json *params,
 416                        struct json **idp)
 417 {
 418     struct json *id = jsonrpc_create_id();
 419     if (idp) {
 420         *idp = json_clone(id);
 421     }
 422     return jsonrpc_create(JSONRPC_REQUEST, method, params, NULL, NULL, id);
 423 }
 424
 425 struct jsonrpc_msg *
 426 jsonrpc_create_notify(const char *method, struct json *params)
 427 {
 428     return jsonrpc_create(JSONRPC_NOTIFY, method, params, NULL, NULL, NULL);
 429 }
 430
 431 struct jsonrpc_msg *
 432 jsonrpc_create_reply(struct json *result, const struct json *id)
 433 {
 434     return jsonrpc_create(JSONRPC_REPLY, NULL, NULL, result, NULL,
 435                            json_clone(id));
 436 }
 437
 438 struct jsonrpc_msg *
 439 jsonrpc_create_error(struct json *error, const struct json *id)
 440 {
 441     return jsonrpc_create(JSONRPC_REPLY, NULL, NULL, NULL, error,
 442                            json_clone(id));
 443 }
 444
 445 const char *
 446 jsonrpc_msg_type_to_string(enum jsonrpc_msg_type type)
 447 {
 448     switch (type) {
 449     case JSONRPC_REQUEST:
 450         return "request";
 451
 452     case JSONRPC_NOTIFY:
 453         return "notification";
 454
 455     case JSONRPC_REPLY:
 456         return "reply";
 457
 458     case JSONRPC_ERROR:
 459         return "error";
 460     }
 461     return "(null)";
 462 }
 463
 464 char *
 465 jsonrpc_msg_is_valid(const struct jsonrpc_msg *m)
 466 {
 467     const char *type_name;
 468     unsigned int pattern;
 469
 470     if (m->params && m->params->type != JSON_ARRAY) {
 471         return xstrdup("\"params\" must be JSON array");
 472     }
 473
 474     switch (m->type) {
 475     case JSONRPC_REQUEST:
 476         pattern = 0x11001;
 477         break;
 478
 479     case JSONRPC_NOTIFY:
 480         pattern = 0x11000;
 481         break;
 482
 483     case JSONRPC_REPLY:
 484         pattern = 0x00101;
 485         break;
 486
 487     case JSONRPC_ERROR:
 488         pattern = 0x00011;
 489         break;
 490
 491     default:
 492         return xasprintf("invalid JSON-RPC message type %d", m->type);
 493     }
 494
 495     type_name = jsonrpc_msg_type_to_string(m->type);
 496     if ((m->method != NULL) != ((pattern & 0x10000) != 0)) {
 497         return xasprintf("%s must%s have \"method\"",
 498                          type_name, (pattern & 0x10000) ? "" : " not");
 499
 500     }
 501     if ((m->params != NULL) != ((pattern & 0x1000) != 0)) {
 502         return xasprintf("%s must%s have \"params\"",
 503                          type_name, (pattern & 0x1000) ? "" : " not");
 504
 505     }
 506     if ((m->result != NULL) != ((pattern & 0x100) != 0)) {
 507         return xasprintf("%s must%s have \"result\"",
 508                          type_name, (pattern & 0x100) ? "" : " not");
 509
 510     }
 511     if ((m->error != NULL) != ((pattern & 0x10) != 0)) {
 512         return xasprintf("%s must%s have \"error\"",
 513                          type_name, (pattern & 0x10) ? "" : " not");
 514
 515     }
 516     if ((m->id != NULL) != ((pattern & 0x1) != 0)) {
 517         return xasprintf("%s must%s have \"id\"",
 518                          type_name, (pattern & 0x1) ? "" : " not");
 519
 520     }
 521     return NULL;
 522 }
 523
 524 void
 525 jsonrpc_msg_destroy(struct jsonrpc_msg *m)
 526 {
 527     if (m) {
 528         free(m->method);
 529         json_destroy(m->params);
 530         json_destroy(m->result);
 531         json_destroy(m->error);
 532         json_destroy(m->id);
 533         free(m);
 534     }
 535 }
 536
 537 static struct json *
 538 null_from_json_null(struct json *json)
 539 {
 540     if (json && json->type == JSON_NULL) {
 541         json_destroy(json);
 542         return NULL;
 543     }
 544     return json;
 545 }
 546
 547 char *
 548 jsonrpc_msg_from_json(struct json *json, struct jsonrpc_msg **msgp)
 549 {
 550     struct json *method = NULL;
 551     struct jsonrpc_msg *msg = NULL;
 552     struct shash *object;
 553     char *error;
 554
 555     if (json->type != JSON_OBJECT) {
 556         error = xstrdup("message is not a JSON object");
 557         goto exit;
 558     }
 559     object = json_object(json);
 560
 561     method = shash_find_and_delete(object, "method");
 562     if (method && method->type != JSON_STRING) {
 563         error = xstrdup("method is not a JSON string");
 564         goto exit;
 565     }
 566
 567     msg = xzalloc(sizeof *msg);
 568     msg->method = method ? xstrdup(method->u.string) : NULL;
 569     msg->params = null_from_json_null(shash_find_and_delete(object, "params"));
 570     msg->result = null_from_json_null(shash_find_and_delete(object, "result"));
 571     msg->error = null_from_json_null(shash_find_and_delete(object, "error"));
 572     msg->id = null_from_json_null(shash_find_and_delete(object, "id"));
 573     msg->type = (msg->result ? JSONRPC_REPLY
 574                  : msg->error ? JSONRPC_ERROR
 575                  : msg->id ? JSONRPC_REQUEST
 576                  : JSONRPC_NOTIFY);
 577     if (!shash_is_empty(object)) {
 578         error = xasprintf("message has unexpected member \"%s\"",
 579                           shash_first(object)->name);
 580         goto exit;
 581     }
 582     error = jsonrpc_msg_is_valid(msg);
 583     if (error) {
 584         goto exit;
 585     }
 586
 587 exit:
 588     json_destroy(method);
 589     json_destroy(json);
 590     if (error) {
 591         jsonrpc_msg_destroy(msg);
 592         msg = NULL;
 593     }
 594     *msgp = msg;
 595     return error;
 596 }
 597
 598 struct json *
 599 jsonrpc_msg_to_json(struct jsonrpc_msg *m)
 600 {
 601     struct json *json = json_object_create();
 602
 603     if (m->method) {
 604         json_object_put(json, "method", json_string_create_nocopy(m->method));
 605     }
 606
 607     if (m->params) {
 608         json_object_put(json, "params", m->params);
 609     }
 610
 611     if (m->result) {
 612         json_object_put(json, "result", m->result);
 613     } else if (m->type == JSONRPC_ERROR) {
 614         json_object_put(json, "result", json_null_create());
 615     }
 616
 617     if (m->error) {
 618         json_object_put(json, "error", m->error);
 619     } else if (m->type == JSONRPC_REPLY) {
 620         json_object_put(json, "error", json_null_create());
 621     }
 622
 623     if (m->id) {
 624         json_object_put(json, "id", m->id);
 625     } else if (m->type == JSONRPC_NOTIFY) {
 626         json_object_put(json, "id", json_null_create());
 627     }
 628
 629     free(m);
 630
 631     return json;
 632 }
 633 \f
 634 /* A JSON-RPC session with reconnection. */
 635
 636 struct jsonrpc_session {
 637     struct reconnect *reconnect;
 638     struct jsonrpc *rpc;
 639     struct stream *stream;
 640     unsigned int seqno;
 641 };
 642
 643 /* Creates and returns a jsonrpc_session that connects and reconnects, with
 644  * back-off, to 'name', which should be a string acceptable to
 645  * stream_open(). */
 646 struct jsonrpc_session *
 647 jsonrpc_session_open(const char *name)
 648 {
 649     struct jsonrpc_session *s;
 650
 651     s = xmalloc(sizeof *s);
 652     s->reconnect = reconnect_create(time_msec());
 653     reconnect_set_name(s->reconnect, name);
 654     reconnect_enable(s->reconnect, time_msec());
 655     s->rpc = NULL;
 656     s->stream = NULL;
 657     s->seqno = 0;
 658
 659     return s;
 660 }
 661
 662 /* Creates and returns a jsonrpc_session that is initially connected to
 663  * 'jsonrpc'.  If the connection is dropped, it will not be reconnected. */
 664 struct jsonrpc_session *
 665 jsonrpc_session_open_unreliably(struct jsonrpc *jsonrpc)
 666 {
 667     struct jsonrpc_session *s;
 668
 669     s = xmalloc(sizeof *s);
 670     s->reconnect = reconnect_create(time_msec());
 671     reconnect_set_name(s->reconnect, jsonrpc_get_name(jsonrpc));
 672     reconnect_set_max_tries(s->reconnect, 0);
 673     reconnect_connected(s->reconnect, time_msec());
 674     s->rpc = jsonrpc;
 675     s->stream = NULL;
 676     s->seqno = 0;
 677
 678     return s;
 679 }
 680
 681 void
 682 jsonrpc_session_close(struct jsonrpc_session *s)
 683 {
 684     if (s) {
 685         jsonrpc_close(s->rpc);
 686         reconnect_destroy(s->reconnect);
 687         stream_close(s->stream);
 688         free(s);
 689     }
 690 }
 691
 692 static void
 693 jsonrpc_session_disconnect(struct jsonrpc_session *s)
 694 {
 695     if (s->rpc) {
 696         jsonrpc_error(s->rpc, EOF);
 697         jsonrpc_close(s->rpc);
 698         s->rpc = NULL;
 699         s->seqno++;
 700     } else if (s->stream) {
 701         stream_close(s->stream);
 702         s->stream = NULL;
 703         s->seqno++;
 704     }
 705 }
 706
 707 static void
 708 jsonrpc_session_connect(struct jsonrpc_session *s)
 709 {
 710     int error;
 711
 712     jsonrpc_session_disconnect(s);
 713     error = stream_open(reconnect_get_name(s->reconnect), &s->stream);
 714     if (error) {
 715         reconnect_connect_failed(s->reconnect, time_msec(), error);
 716     } else {
 717         reconnect_connecting(s->reconnect, time_msec());
 718     }
 719     s->seqno++;
 720 }
 721
 722 void
 723 jsonrpc_session_run(struct jsonrpc_session *s)
 724 {
 725     if (s->rpc) {
 726         int error;
 727
 728         jsonrpc_run(s->rpc);
 729         error = jsonrpc_get_status(s->rpc);
 730         if (error) {
 731             reconnect_disconnected(s->reconnect, time_msec(), 0);
 732             jsonrpc_session_disconnect(s);
 733         }
 734     } else if (s->stream) {
 735         int error;
 736
 737         stream_run(s->stream);
 738         error = stream_connect(s->stream);
 739         if (!error) {
 740             reconnect_connected(s->reconnect, time_msec());
 741             s->rpc = jsonrpc_open(s->stream);
 742             s->stream = NULL;
 743         } else if (error != EAGAIN) {
 744             reconnect_connect_failed(s->reconnect, time_msec(), error);
 745             stream_close(s->stream);
 746             s->stream = NULL;
 747         }
 748     }
 749
 750     switch (reconnect_run(s->reconnect, time_msec())) {
 751     case RECONNECT_CONNECT:
 752         jsonrpc_session_connect(s);
 753         break;
 754
 755     case RECONNECT_DISCONNECT:
 756         reconnect_disconnected(s->reconnect, time_msec(), 0);
 757         jsonrpc_session_disconnect(s);
 758         break;
 759
 760     case RECONNECT_PROBE:
 761         if (s->rpc) {
 762             struct json *params;
 763             struct jsonrpc_msg *request;
 764
 765             params = json_array_create_empty();
 766             request = jsonrpc_create_request("echo", params, NULL);
 767             json_destroy(request->id);
 768             request->id = json_string_create("echo");
 769             jsonrpc_send(s->rpc, request);
 770         }
 771         break;
 772     }
 773 }
 774
 775 void
 776 jsonrpc_session_wait(struct jsonrpc_session *s)
 777 {
 778     if (s->rpc) {
 779         jsonrpc_wait(s->rpc);
 780     } else if (s->stream) {
 781         stream_run_wait(s->stream);
 782         stream_connect_wait(s->stream);
 783     }
 784     reconnect_wait(s->reconnect, time_msec());
 785 }
 786
 787 size_t
 788 jsonrpc_session_get_backlog(const struct jsonrpc_session *s)
 789 {
 790     return s->rpc ? jsonrpc_get_backlog(s->rpc) : 0;
 791 }
 792
 793 const char *
 794 jsonrpc_session_get_name(const struct jsonrpc_session *s)
 795 {
 796     return reconnect_get_name(s->reconnect);
 797 }
 798
 799 /* Always takes ownership of 'msg', regardless of success. */
 800 int
 801 jsonrpc_session_send(struct jsonrpc_session *s, struct jsonrpc_msg *msg)
 802 {
 803     if (s->rpc) {
 804         return jsonrpc_send(s->rpc, msg);
 805     } else {
 806         jsonrpc_msg_destroy(msg);
 807         return ENOTCONN;
 808     }
 809 }
 810
 811 struct jsonrpc_msg *
 812 jsonrpc_session_recv(struct jsonrpc_session *s)
 813 {
 814     if (s->rpc) {
 815         struct jsonrpc_msg *msg;
 816         jsonrpc_recv(s->rpc, &msg);
 817         if (msg) {
 818             reconnect_received(s->reconnect, time_msec());
 819             if (msg->type == JSONRPC_REQUEST && !strcmp(msg->method, "echo")) {
 820                 /* Echo request.  Send reply. */
 821                 struct jsonrpc_msg *reply;
 822
 823                 reply = jsonrpc_create_reply(json_clone(msg->params), msg->id);
 824                 jsonrpc_session_send(s, reply);
 825             } else if (msg->type == JSONRPC_REPLY
 826                 && msg->id && msg->id->type == JSON_STRING
 827                 && !strcmp(msg->id->u.string, "echo")) {
 828                 /* It's a reply to our echo request.  Suppress it. */
 829             } else {
 830                 return msg;
 831             }
 832             jsonrpc_msg_destroy(msg);
 833         }
 834     }
 835     return NULL;
 836 }
 837
 838 void
 839 jsonrpc_session_recv_wait(struct jsonrpc_session *s)
 840 {
 841     if (s->rpc) {
 842         jsonrpc_recv_wait(s->rpc);
 843     }
 844 }
 845
 846 bool
 847 jsonrpc_session_is_alive(const struct jsonrpc_session *s)
 848 {
 849     return s->rpc || s->stream || reconnect_get_max_tries(s->reconnect);
 850 }
 851
 852 bool
 853 jsonrpc_session_is_connected(const struct jsonrpc_session *s)
 854 {
 855     return s->rpc != NULL;
 856 }
 857
 858 unsigned int
 859 jsonrpc_session_get_seqno(const struct jsonrpc_session *s)
 860 {
 861     return s->seqno;
 862 }
 863
 864 void
 865 jsonrpc_session_force_reconnect(struct jsonrpc_session *s)
 866 {
 867     reconnect_force_reconnect(s->reconnect, time_msec());
 868 }