lib/jsonrpc.c

   1 /*
   2  * Copyright (c) 2009, 2010, 2011, 2012, 2013 Nicira, Inc.
   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 <errno.h>
  22
  23 #include "byteq.h"
  24 #include "dynamic-string.h"
  25 #include "fatal-signal.h"
  26 #include "json.h"
  27 #include "list.h"
  28 #include "ofpbuf.h"
  29 #include "ovs-thread.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     uint8_t input_buffer[512];
  46     struct json_parser *parser;
  47     struct jsonrpc_msg *received;
  48
  49     /* Output. */
  50     struct list output;         /* Contains "struct ofpbuf"s. */
  51     size_t backlog;
  52 };
  53
  54 /* Rate limit for error messages. */
  55 static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 5);
  56
  57 static void jsonrpc_received(struct jsonrpc *);
  58 static void jsonrpc_cleanup(struct jsonrpc *);
  59 static void jsonrpc_error(struct jsonrpc *, int error);
  60
  61 /* This is just the same as stream_open() except that it uses the default
  62  * JSONRPC ports if none is specified. */
  63 int
  64 jsonrpc_stream_open(const char *name, struct stream **streamp, uint8_t dscp)
  65 {
  66     return stream_open_with_default_ports(name, JSONRPC_TCP_PORT,
  67                                           JSONRPC_SSL_PORT, streamp,
  68                                           dscp);
  69 }
  70
  71 /* This is just the same as pstream_open() except that it uses the default
  72  * JSONRPC ports if none is specified. */
  73 int
  74 jsonrpc_pstream_open(const char *name, struct pstream **pstreamp, uint8_t dscp)
  75 {
  76     return pstream_open_with_default_ports(name, JSONRPC_TCP_PORT,
  77                                            JSONRPC_SSL_PORT, pstreamp, dscp);
  78 }
  79
  80 /* Returns a new JSON-RPC stream that uses 'stream' for input and output.  The
  81  * new jsonrpc object takes ownership of 'stream'. */
  82 struct jsonrpc *
  83 jsonrpc_open(struct stream *stream)
  84 {
  85     struct jsonrpc *rpc;
  86
  87     ovs_assert(stream != NULL);
  88
  89     rpc = xzalloc(sizeof *rpc);
  90     rpc->name = xstrdup(stream_get_name(stream));
  91     rpc->stream = stream;
  92     byteq_init(&rpc->input, rpc->input_buffer, sizeof rpc->input_buffer);
  93     list_init(&rpc->output);
  94
  95     return rpc;
  96 }
  97
  98 /* Destroys 'rpc', closing the stream on which it is based, and frees its
  99  * memory. */
 100 void
 101 jsonrpc_close(struct jsonrpc *rpc)
 102 {
 103     if (rpc) {
 104         jsonrpc_cleanup(rpc);
 105         free(rpc->name);
 106         free(rpc);
 107     }
 108 }
 109
 110 /* Performs periodic maintenance on 'rpc', such as flushing output buffers. */
 111 void
 112 jsonrpc_run(struct jsonrpc *rpc)
 113 {
 114     if (rpc->status) {
 115         return;
 116     }
 117
 118     stream_run(rpc->stream);
 119     while (!list_is_empty(&rpc->output)) {
 120         struct ofpbuf *buf = ofpbuf_from_list(rpc->output.next);
 121         int retval;
 122
 123         retval = stream_send(rpc->stream, buf->data, buf->size);
 124         if (retval >= 0) {
 125             rpc->backlog -= retval;
 126             ofpbuf_pull(buf, retval);
 127             if (!buf->size) {
 128                 list_remove(&buf->list_node);
 129                 ofpbuf_delete(buf);
 130             }
 131         } else {
 132             if (retval != -EAGAIN) {
 133                 VLOG_WARN_RL(&rl, "%s: send error: %s",
 134                              rpc->name, ovs_strerror(-retval));
 135                 jsonrpc_error(rpc, -retval);
 136             }
 137             break;
 138         }
 139     }
 140 }
 141
 142 /* Arranges for the poll loop to wake up when 'rpc' needs to perform
 143  * maintenance activities. */
 144 void
 145 jsonrpc_wait(struct jsonrpc *rpc)
 146 {
 147     if (!rpc->status) {
 148         stream_run_wait(rpc->stream);
 149         if (!list_is_empty(&rpc->output)) {
 150             stream_send_wait(rpc->stream);
 151         }
 152     }
 153 }
 154
 155 /*
 156  * Returns the current status of 'rpc'.  The possible return values are:
 157  * - 0: no error yet
 158  * - >0: errno value
 159  * - EOF: end of file (remote end closed connection; not necessarily an error).
 160  *
 161  * When this functions nonzero, 'rpc' is effectively out of commission.  'rpc'
 162  * will not receive any more messages and any further messages that one
 163  * attempts to send with 'rpc' will be discarded.  The caller can keep 'rpc'
 164  * around as long as it wants, but it's not going to provide any more useful
 165  * services.
 166  */
 167 int
 168 jsonrpc_get_status(const struct jsonrpc *rpc)
 169 {
 170     return rpc->status;
 171 }
 172
 173 /* Returns the number of bytes buffered by 'rpc' to be written to the
 174  * underlying stream.  Always returns 0 if 'rpc' has encountered an error or if
 175  * the remote end closed the connection. */
 176 size_t
 177 jsonrpc_get_backlog(const struct jsonrpc *rpc)
 178 {
 179     return rpc->status ? 0 : rpc->backlog;
 180 }
 181
 182 /* Returns the number of bytes that have been received on 'rpc''s underlying
 183  * stream.  (The value wraps around if it exceeds UINT_MAX.) */
 184 unsigned int
 185 jsonrpc_get_received_bytes(const struct jsonrpc *rpc)
 186 {
 187     return rpc->input.head;
 188 }
 189
 190 /* Returns 'rpc''s name, that is, the name returned by stream_get_name() for
 191  * the stream underlying 'rpc' when 'rpc' was created. */
 192 const char *
 193 jsonrpc_get_name(const struct jsonrpc *rpc)
 194 {
 195     return rpc->name;
 196 }
 197
 198 static void
 199 jsonrpc_log_msg(const struct jsonrpc *rpc, const char *title,
 200                 const struct jsonrpc_msg *msg)
 201 {
 202     if (VLOG_IS_DBG_ENABLED()) {
 203         struct ds s = DS_EMPTY_INITIALIZER;
 204         if (msg->method) {
 205             ds_put_format(&s, ", method=\"%s\"", msg->method);
 206         }
 207         if (msg->params) {
 208             ds_put_cstr(&s, ", params=");
 209             json_to_ds(msg->params, 0, &s);
 210         }
 211         if (msg->result) {
 212             ds_put_cstr(&s, ", result=");
 213             json_to_ds(msg->result, 0, &s);
 214         }
 215         if (msg->error) {
 216             ds_put_cstr(&s, ", error=");
 217             json_to_ds(msg->error, 0, &s);
 218         }
 219         if (msg->id) {
 220             ds_put_cstr(&s, ", id=");
 221             json_to_ds(msg->id, 0, &s);
 222         }
 223         VLOG_DBG("%s: %s %s%s", rpc->name, title,
 224                  jsonrpc_msg_type_to_string(msg->type), ds_cstr(&s));
 225         ds_destroy(&s);
 226     }
 227 }
 228
 229 /* Schedules 'msg' to be sent on 'rpc' and returns 'rpc''s status (as with
 230  * jsonrpc_get_status()).
 231  *
 232  * If 'msg' cannot be sent immediately, it is appended to a buffer.  The caller
 233  * is responsible for ensuring that the amount of buffered data is somehow
 234  * limited.  (jsonrpc_get_backlog() returns the amount of data currently
 235  * buffered in 'rpc'.)
 236  *
 237  * Always takes ownership of 'msg', regardless of success. */
 238 int
 239 jsonrpc_send(struct jsonrpc *rpc, struct jsonrpc_msg *msg)
 240 {
 241     struct ofpbuf *buf;
 242     struct json *json;
 243     size_t length;
 244     char *s;
 245
 246     if (rpc->status) {
 247         jsonrpc_msg_destroy(msg);
 248         return rpc->status;
 249     }
 250
 251     jsonrpc_log_msg(rpc, "send", msg);
 252
 253     json = jsonrpc_msg_to_json(msg);
 254     s = json_to_string(json, 0);
 255     length = strlen(s);
 256     json_destroy(json);
 257
 258     buf = xmalloc(sizeof *buf);
 259     ofpbuf_use(buf, s, length);
 260     buf->size = length;
 261     list_push_back(&rpc->output, &buf->list_node);
 262     rpc->backlog += length;
 263
 264     if (rpc->backlog == length) {
 265         jsonrpc_run(rpc);
 266     }
 267     return rpc->status;
 268 }
 269
 270 /* Attempts to receive a message from 'rpc'.
 271  *
 272  * If successful, stores the received message in '*msgp' and returns 0.  The
 273  * caller takes ownership of '*msgp' and must eventually destroy it with
 274  * jsonrpc_msg_destroy().
 275  *
 276  * Otherwise, stores NULL in '*msgp' and returns one of the following:
 277  *
 278  *   - EAGAIN: No message has been received.
 279  *
 280  *   - EOF: The remote end closed the connection gracefully.
 281  *
 282  *   - Otherwise an errno value that represents a JSON-RPC protocol violation
 283  *     or another error fatal to the connection.  'rpc' will not send or
 284  *     receive any more messages.
 285  */
 286 int
 287 jsonrpc_recv(struct jsonrpc *rpc, struct jsonrpc_msg **msgp)
 288 {
 289     int i;
 290
 291     *msgp = NULL;
 292     if (rpc->status) {
 293         return rpc->status;
 294     }
 295
 296     for (i = 0; i < 50; i++) {
 297         if (rpc->received) {
 298             *msgp = rpc->received;
 299             rpc->received = NULL;
 300             return 0;
 301         } else if (byteq_is_empty(&rpc->input)) {
 302             size_t chunk;
 303             int retval;
 304
 305             chunk = byteq_headroom(&rpc->input);
 306             retval = stream_recv(rpc->stream, byteq_head(&rpc->input), chunk);
 307             if (retval < 0) {
 308                 if (retval == -EAGAIN) {
 309                     return EAGAIN;
 310                 } else {
 311                     VLOG_WARN_RL(&rl, "%s: receive error: %s",
 312                                  rpc->name, ovs_strerror(-retval));
 313                     jsonrpc_error(rpc, -retval);
 314                     return rpc->status;
 315                 }
 316             } else if (retval == 0) {
 317                 jsonrpc_error(rpc, EOF);
 318                 return EOF;
 319             }
 320             byteq_advance_head(&rpc->input, retval);
 321         } else {
 322             size_t n, used;
 323
 324             if (!rpc->parser) {
 325                 rpc->parser = json_parser_create(0);
 326             }
 327             n = byteq_tailroom(&rpc->input);
 328             used = json_parser_feed(rpc->parser,
 329                                     (char *) byteq_tail(&rpc->input), n);
 330             byteq_advance_tail(&rpc->input, used);
 331             if (json_parser_is_done(rpc->parser)) {
 332                 jsonrpc_received(rpc);
 333                 if (rpc->status) {
 334                     const struct byteq *q = &rpc->input;
 335                     if (q->head <= q->size) {
 336                         stream_report_content(q->buffer, q->head,
 337                                               STREAM_JSONRPC,
 338                                               THIS_MODULE, rpc->name);
 339                     }
 340                     return rpc->status;
 341                 }
 342             }
 343         }
 344     }
 345
 346     return EAGAIN;
 347 }
 348
 349 /* Causes the poll loop to wake up when jsonrpc_recv() may return a value other
 350  * than EAGAIN. */
 351 void
 352 jsonrpc_recv_wait(struct jsonrpc *rpc)
 353 {
 354     if (rpc->status || rpc->received || !byteq_is_empty(&rpc->input)) {
 355         poll_immediate_wake_at(rpc->name);
 356     } else {
 357         stream_recv_wait(rpc->stream);
 358     }
 359 }
 360
 361 /* Sends 'msg' on 'rpc' and waits for it to be successfully queued to the
 362  * underlying stream.  Returns 0 if 'msg' was sent successfully, otherwise a
 363  * status value (see jsonrpc_get_status()).
 364  *
 365  * Always takes ownership of 'msg', regardless of success. */
 366 int
 367 jsonrpc_send_block(struct jsonrpc *rpc, struct jsonrpc_msg *msg)
 368 {
 369     int error;
 370
 371     fatal_signal_run();
 372
 373     error = jsonrpc_send(rpc, msg);
 374     if (error) {
 375         return error;
 376     }
 377
 378     for (;;) {
 379         jsonrpc_run(rpc);
 380         if (list_is_empty(&rpc->output) || rpc->status) {
 381             return rpc->status;
 382         }
 383         jsonrpc_wait(rpc);
 384         poll_block();
 385     }
 386 }
 387
 388 /* Waits for a message to be received on 'rpc'.  Same semantics as
 389  * jsonrpc_recv() except that EAGAIN will never be returned. */
 390 int
 391 jsonrpc_recv_block(struct jsonrpc *rpc, struct jsonrpc_msg **msgp)
 392 {
 393     for (;;) {
 394         int error = jsonrpc_recv(rpc, msgp);
 395         if (error != EAGAIN) {
 396             fatal_signal_run();
 397             return error;
 398         }
 399
 400         jsonrpc_run(rpc);
 401         jsonrpc_wait(rpc);
 402         jsonrpc_recv_wait(rpc);
 403         poll_block();
 404     }
 405 }
 406
 407 /* Sends 'request' to 'rpc' then waits for a reply.  The return value is 0 if
 408  * successful, in which case '*replyp' is set to the reply, which the caller
 409  * must eventually free with jsonrpc_msg_destroy().  Otherwise returns a status
 410  * value (see jsonrpc_get_status()).
 411  *
 412  * Discards any message received on 'rpc' that is not a reply to 'request'
 413  * (based on message id).
 414  *
 415  * Always takes ownership of 'request', regardless of success. */
 416 int
 417 jsonrpc_transact_block(struct jsonrpc *rpc, struct jsonrpc_msg *request,
 418                        struct jsonrpc_msg **replyp)
 419 {
 420     struct jsonrpc_msg *reply = NULL;
 421     struct json *id;
 422     int error;
 423
 424     id = json_clone(request->id);
 425     error = jsonrpc_send_block(rpc, request);
 426     if (!error) {
 427         for (;;) {
 428             error = jsonrpc_recv_block(rpc, &reply);
 429             if (error) {
 430                 break;
 431             }
 432             if ((reply->type == JSONRPC_REPLY || reply->type == JSONRPC_ERROR)
 433                 && json_equal(id, reply->id)) {
 434                 break;
 435             }
 436             jsonrpc_msg_destroy(reply);
 437         }
 438     }
 439     *replyp = error ? NULL : reply;
 440     json_destroy(id);
 441     return error;
 442 }
 443
 444 static void
 445 jsonrpc_received(struct jsonrpc *rpc)
 446 {
 447     struct jsonrpc_msg *msg;
 448     struct json *json;
 449     char *error;
 450
 451     json = json_parser_finish(rpc->parser);
 452     rpc->parser = NULL;
 453     if (json->type == JSON_STRING) {
 454         VLOG_WARN_RL(&rl, "%s: error parsing stream: %s",
 455                      rpc->name, json_string(json));
 456         jsonrpc_error(rpc, EPROTO);
 457         json_destroy(json);
 458         return;
 459     }
 460
 461     error = jsonrpc_msg_from_json(json, &msg);
 462     if (error) {
 463         VLOG_WARN_RL(&rl, "%s: received bad JSON-RPC message: %s",
 464                      rpc->name, error);
 465         free(error);
 466         jsonrpc_error(rpc, EPROTO);
 467         return;
 468     }
 469
 470     jsonrpc_log_msg(rpc, "received", msg);
 471     rpc->received = msg;
 472 }
 473
 474 static void
 475 jsonrpc_error(struct jsonrpc *rpc, int error)
 476 {
 477     ovs_assert(error);
 478     if (!rpc->status) {
 479         rpc->status = error;
 480         jsonrpc_cleanup(rpc);
 481     }
 482 }
 483
 484 static void
 485 jsonrpc_cleanup(struct jsonrpc *rpc)
 486 {
 487     stream_close(rpc->stream);
 488     rpc->stream = NULL;
 489
 490     json_parser_abort(rpc->parser);
 491     rpc->parser = NULL;
 492
 493     jsonrpc_msg_destroy(rpc->received);
 494     rpc->received = NULL;
 495
 496     ofpbuf_list_delete(&rpc->output);
 497     rpc->backlog = 0;
 498 }
 499 \f
 500 static struct jsonrpc_msg *
 501 jsonrpc_create(enum jsonrpc_msg_type type, const char *method,
 502                 struct json *params, struct json *result, struct json *error,
 503                 struct json *id)
 504 {
 505     struct jsonrpc_msg *msg = xmalloc(sizeof *msg);
 506     msg->type = type;
 507     msg->method = method ? xstrdup(method) : NULL;
 508     msg->params = params;
 509     msg->result = result;
 510     msg->error = error;
 511     msg->id = id;
 512     return msg;
 513 }
 514
 515 static struct json *
 516 jsonrpc_create_id(void)
 517 {
 518     static atomic_uint next_id = ATOMIC_VAR_INIT(0);
 519     unsigned int id;
 520
 521     atomic_add(&next_id, 1, &id);
 522     return json_integer_create(id);
 523 }
 524
 525 struct jsonrpc_msg *
 526 jsonrpc_create_request(const char *method, struct json *params,
 527                        struct json **idp)
 528 {
 529     struct json *id = jsonrpc_create_id();
 530     if (idp) {
 531         *idp = json_clone(id);
 532     }
 533     return jsonrpc_create(JSONRPC_REQUEST, method, params, NULL, NULL, id);
 534 }
 535
 536 struct jsonrpc_msg *
 537 jsonrpc_create_notify(const char *method, struct json *params)
 538 {
 539     return jsonrpc_create(JSONRPC_NOTIFY, method, params, NULL, NULL, NULL);
 540 }
 541
 542 struct jsonrpc_msg *
 543 jsonrpc_create_reply(struct json *result, const struct json *id)
 544 {
 545     return jsonrpc_create(JSONRPC_REPLY, NULL, NULL, result, NULL,
 546                            json_clone(id));
 547 }
 548
 549 struct jsonrpc_msg *
 550 jsonrpc_create_error(struct json *error, const struct json *id)
 551 {
 552     return jsonrpc_create(JSONRPC_REPLY, NULL, NULL, NULL, error,
 553                            json_clone(id));
 554 }
 555
 556 const char *
 557 jsonrpc_msg_type_to_string(enum jsonrpc_msg_type type)
 558 {
 559     switch (type) {
 560     case JSONRPC_REQUEST:
 561         return "request";
 562
 563     case JSONRPC_NOTIFY:
 564         return "notification";
 565
 566     case JSONRPC_REPLY:
 567         return "reply";
 568
 569     case JSONRPC_ERROR:
 570         return "error";
 571     }
 572     return "(null)";
 573 }
 574
 575 char *
 576 jsonrpc_msg_is_valid(const struct jsonrpc_msg *m)
 577 {
 578     const char *type_name;
 579     unsigned int pattern;
 580
 581     if (m->params && m->params->type != JSON_ARRAY) {
 582         return xstrdup("\"params\" must be JSON array");
 583     }
 584
 585     switch (m->type) {
 586     case JSONRPC_REQUEST:
 587         pattern = 0x11001;
 588         break;
 589
 590     case JSONRPC_NOTIFY:
 591         pattern = 0x11000;
 592         break;
 593
 594     case JSONRPC_REPLY:
 595         pattern = 0x00101;
 596         break;
 597
 598     case JSONRPC_ERROR:
 599         pattern = 0x00011;
 600         break;
 601
 602     default:
 603         return xasprintf("invalid JSON-RPC message type %d", m->type);
 604     }
 605
 606     type_name = jsonrpc_msg_type_to_string(m->type);
 607     if ((m->method != NULL) != ((pattern & 0x10000) != 0)) {
 608         return xasprintf("%s must%s have \"method\"",
 609                          type_name, (pattern & 0x10000) ? "" : " not");
 610
 611     }
 612     if ((m->params != NULL) != ((pattern & 0x1000) != 0)) {
 613         return xasprintf("%s must%s have \"params\"",
 614                          type_name, (pattern & 0x1000) ? "" : " not");
 615
 616     }
 617     if ((m->result != NULL) != ((pattern & 0x100) != 0)) {
 618         return xasprintf("%s must%s have \"result\"",
 619                          type_name, (pattern & 0x100) ? "" : " not");
 620
 621     }
 622     if ((m->error != NULL) != ((pattern & 0x10) != 0)) {
 623         return xasprintf("%s must%s have \"error\"",
 624                          type_name, (pattern & 0x10) ? "" : " not");
 625
 626     }
 627     if ((m->id != NULL) != ((pattern & 0x1) != 0)) {
 628         return xasprintf("%s must%s have \"id\"",
 629                          type_name, (pattern & 0x1) ? "" : " not");
 630
 631     }
 632     return NULL;
 633 }
 634
 635 void
 636 jsonrpc_msg_destroy(struct jsonrpc_msg *m)
 637 {
 638     if (m) {
 639         free(m->method);
 640         json_destroy(m->params);
 641         json_destroy(m->result);
 642         json_destroy(m->error);
 643         json_destroy(m->id);
 644         free(m);
 645     }
 646 }
 647
 648 static struct json *
 649 null_from_json_null(struct json *json)
 650 {
 651     if (json && json->type == JSON_NULL) {
 652         json_destroy(json);
 653         return NULL;
 654     }
 655     return json;
 656 }
 657
 658 char *
 659 jsonrpc_msg_from_json(struct json *json, struct jsonrpc_msg **msgp)
 660 {
 661     struct json *method = NULL;
 662     struct jsonrpc_msg *msg = NULL;
 663     struct shash *object;
 664     char *error;
 665
 666     if (json->type != JSON_OBJECT) {
 667         error = xstrdup("message is not a JSON object");
 668         goto exit;
 669     }
 670     object = json_object(json);
 671
 672     method = shash_find_and_delete(object, "method");
 673     if (method && method->type != JSON_STRING) {
 674         error = xstrdup("method is not a JSON string");
 675         goto exit;
 676     }
 677
 678     msg = xzalloc(sizeof *msg);
 679     msg->method = method ? xstrdup(method->u.string) : NULL;
 680     msg->params = null_from_json_null(shash_find_and_delete(object, "params"));
 681     msg->result = null_from_json_null(shash_find_and_delete(object, "result"));
 682     msg->error = null_from_json_null(shash_find_and_delete(object, "error"));
 683     msg->id = null_from_json_null(shash_find_and_delete(object, "id"));
 684     msg->type = (msg->result ? JSONRPC_REPLY
 685                  : msg->error ? JSONRPC_ERROR
 686                  : msg->id ? JSONRPC_REQUEST
 687                  : JSONRPC_NOTIFY);
 688     if (!shash_is_empty(object)) {
 689         error = xasprintf("message has unexpected member \"%s\"",
 690                           shash_first(object)->name);
 691         goto exit;
 692     }
 693     error = jsonrpc_msg_is_valid(msg);
 694     if (error) {
 695         goto exit;
 696     }
 697
 698 exit:
 699     json_destroy(method);
 700     json_destroy(json);
 701     if (error) {
 702         jsonrpc_msg_destroy(msg);
 703         msg = NULL;
 704     }
 705     *msgp = msg;
 706     return error;
 707 }
 708
 709 struct json *
 710 jsonrpc_msg_to_json(struct jsonrpc_msg *m)
 711 {
 712     struct json *json = json_object_create();
 713
 714     if (m->method) {
 715         json_object_put(json, "method", json_string_create_nocopy(m->method));
 716     }
 717
 718     if (m->params) {
 719         json_object_put(json, "params", m->params);
 720     }
 721
 722     if (m->result) {
 723         json_object_put(json, "result", m->result);
 724     } else if (m->type == JSONRPC_ERROR) {
 725         json_object_put(json, "result", json_null_create());
 726     }
 727
 728     if (m->error) {
 729         json_object_put(json, "error", m->error);
 730     } else if (m->type == JSONRPC_REPLY) {
 731         json_object_put(json, "error", json_null_create());
 732     }
 733
 734     if (m->id) {
 735         json_object_put(json, "id", m->id);
 736     } else if (m->type == JSONRPC_NOTIFY) {
 737         json_object_put(json, "id", json_null_create());
 738     }
 739
 740     free(m);
 741
 742     return json;
 743 }
 744 \f
 745 /* A JSON-RPC session with reconnection. */
 746
 747 struct jsonrpc_session {
 748     struct reconnect *reconnect;
 749     struct jsonrpc *rpc;
 750     struct stream *stream;
 751     struct pstream *pstream;
 752     int last_error;
 753     unsigned int seqno;
 754     uint8_t dscp;
 755 };
 756
 757 /* Creates and returns a jsonrpc_session to 'name', which should be a string
 758  * acceptable to stream_open() or pstream_open().
 759  *
 760  * If 'name' is an active connection method, e.g. "tcp:127.1.2.3", the new
 761  * jsonrpc_session connects to 'name'.  If 'retry' is true, then the new
 762  * session connects and reconnects to 'name', with backoff.  If 'retry' is
 763  * false, the new session will only try to connect once and after a connection
 764  * failure or a disconnection jsonrpc_session_is_alive() will return false for
 765  * the new session.
 766  *
 767  * If 'name' is a passive connection method, e.g. "ptcp:", the new
 768  * jsonrpc_session listens for connections to 'name'.  It maintains at most one
 769  * connection at any given time.  Any new connection causes the previous one
 770  * (if any) to be dropped. */
 771 struct jsonrpc_session *
 772 jsonrpc_session_open(const char *name, bool retry)
 773 {
 774     struct jsonrpc_session *s;
 775
 776     s = xmalloc(sizeof *s);
 777     s->reconnect = reconnect_create(time_msec());
 778     reconnect_set_name(s->reconnect, name);
 779     reconnect_enable(s->reconnect, time_msec());
 780     s->rpc = NULL;
 781     s->stream = NULL;
 782     s->pstream = NULL;
 783     s->seqno = 0;
 784     s->dscp = 0;
 785     s->last_error = 0;
 786
 787     if (!pstream_verify_name(name)) {
 788         reconnect_set_passive(s->reconnect, true, time_msec());
 789     } else if (!retry) {
 790         reconnect_set_max_tries(s->reconnect, 1);
 791         reconnect_set_backoff(s->reconnect, INT_MAX, INT_MAX);
 792     }
 793
 794     if (!stream_or_pstream_needs_probes(name)) {
 795         reconnect_set_probe_interval(s->reconnect, 0);
 796     }
 797
 798     return s;
 799 }
 800
 801 /* Creates and returns a jsonrpc_session that is initially connected to
 802  * 'jsonrpc'.  If the connection is dropped, it will not be reconnected.
 803  *
 804  * On the assumption that such connections are likely to be short-lived
 805  * (e.g. from ovs-vsctl), informational logging for them is suppressed. */
 806 struct jsonrpc_session *
 807 jsonrpc_session_open_unreliably(struct jsonrpc *jsonrpc, uint8_t dscp)
 808 {
 809     struct jsonrpc_session *s;
 810
 811     s = xmalloc(sizeof *s);
 812     s->reconnect = reconnect_create(time_msec());
 813     reconnect_set_quiet(s->reconnect, true);
 814     reconnect_set_name(s->reconnect, jsonrpc_get_name(jsonrpc));
 815     reconnect_set_max_tries(s->reconnect, 0);
 816     reconnect_connected(s->reconnect, time_msec());
 817     s->dscp = dscp;
 818     s->rpc = jsonrpc;
 819     s->stream = NULL;
 820     s->pstream = NULL;
 821     s->seqno = 0;
 822
 823     return s;
 824 }
 825
 826 void
 827 jsonrpc_session_close(struct jsonrpc_session *s)
 828 {
 829     if (s) {
 830         jsonrpc_close(s->rpc);
 831         reconnect_destroy(s->reconnect);
 832         stream_close(s->stream);
 833         pstream_close(s->pstream);
 834         free(s);
 835     }
 836 }
 837
 838 static void
 839 jsonrpc_session_disconnect(struct jsonrpc_session *s)
 840 {
 841     if (s->rpc) {
 842         jsonrpc_error(s->rpc, EOF);
 843         jsonrpc_close(s->rpc);
 844         s->rpc = NULL;
 845         s->seqno++;
 846     } else if (s->stream) {
 847         stream_close(s->stream);
 848         s->stream = NULL;
 849         s->seqno++;
 850     }
 851 }
 852
 853 static void
 854 jsonrpc_session_connect(struct jsonrpc_session *s)
 855 {
 856     const char *name = reconnect_get_name(s->reconnect);
 857     int error;
 858
 859     jsonrpc_session_disconnect(s);
 860     if (!reconnect_is_passive(s->reconnect)) {
 861         error = jsonrpc_stream_open(name, &s->stream, s->dscp);
 862         if (!error) {
 863             reconnect_connecting(s->reconnect, time_msec());
 864         } else {
 865             s->last_error = error;
 866         }
 867     } else {
 868         error = s->pstream ? 0 : jsonrpc_pstream_open(name, &s->pstream,
 869                                                       s->dscp);
 870         if (!error) {
 871             reconnect_listening(s->reconnect, time_msec());
 872         }
 873     }
 874
 875     if (error) {
 876         reconnect_connect_failed(s->reconnect, time_msec(), error);
 877     }
 878     s->seqno++;
 879 }
 880
 881 void
 882 jsonrpc_session_run(struct jsonrpc_session *s)
 883 {
 884     if (s->pstream) {
 885         struct stream *stream;
 886         int error;
 887
 888         error = pstream_accept(s->pstream, &stream);
 889         if (!error) {
 890             if (s->rpc || s->stream) {
 891                 VLOG_INFO_RL(&rl,
 892                              "%s: new connection replacing active connection",
 893                              reconnect_get_name(s->reconnect));
 894                 jsonrpc_session_disconnect(s);
 895             }
 896             reconnect_connected(s->reconnect, time_msec());
 897             s->rpc = jsonrpc_open(stream);
 898         } else if (error != EAGAIN) {
 899             reconnect_listen_error(s->reconnect, time_msec(), error);
 900             pstream_close(s->pstream);
 901             s->pstream = NULL;
 902         }
 903     }
 904
 905     if (s->rpc) {
 906         size_t backlog;
 907         int error;
 908
 909         backlog = jsonrpc_get_backlog(s->rpc);
 910         jsonrpc_run(s->rpc);
 911         if (jsonrpc_get_backlog(s->rpc) < backlog) {
 912             /* Data previously caught in a queue was successfully sent (or
 913              * there's an error, which we'll catch below.)
 914              *
 915              * We don't count data that is successfully sent immediately as
 916              * activity, because there's a lot of queuing downstream from us,
 917              * which means that we can push a lot of data into a connection
 918              * that has stalled and won't ever recover.
 919              */
 920             reconnect_activity(s->reconnect, time_msec());
 921         }
 922
 923         error = jsonrpc_get_status(s->rpc);
 924         if (error) {
 925             reconnect_disconnected(s->reconnect, time_msec(), error);
 926             jsonrpc_session_disconnect(s);
 927             s->last_error = error;
 928         }
 929     } else if (s->stream) {
 930         int error;
 931
 932         stream_run(s->stream);
 933         error = stream_connect(s->stream);
 934         if (!error) {
 935             reconnect_connected(s->reconnect, time_msec());
 936             s->rpc = jsonrpc_open(s->stream);
 937             s->stream = NULL;
 938         } else if (error != EAGAIN) {
 939             reconnect_connect_failed(s->reconnect, time_msec(), error);
 940             stream_close(s->stream);
 941             s->stream = NULL;
 942         }
 943     }
 944
 945     switch (reconnect_run(s->reconnect, time_msec())) {
 946     case RECONNECT_CONNECT:
 947         jsonrpc_session_connect(s);
 948         break;
 949
 950     case RECONNECT_DISCONNECT:
 951         reconnect_disconnected(s->reconnect, time_msec(), 0);
 952         jsonrpc_session_disconnect(s);
 953         break;
 954
 955     case RECONNECT_PROBE:
 956         if (s->rpc) {
 957             struct json *params;
 958             struct jsonrpc_msg *request;
 959
 960             params = json_array_create_empty();
 961             request = jsonrpc_create_request("echo", params, NULL);
 962             json_destroy(request->id);
 963             request->id = json_string_create("echo");
 964             jsonrpc_send(s->rpc, request);
 965         }
 966         break;
 967     }
 968 }
 969
 970 void
 971 jsonrpc_session_wait(struct jsonrpc_session *s)
 972 {
 973     if (s->rpc) {
 974         jsonrpc_wait(s->rpc);
 975     } else if (s->stream) {
 976         stream_run_wait(s->stream);
 977         stream_connect_wait(s->stream);
 978     }
 979     if (s->pstream) {
 980         pstream_wait(s->pstream);
 981     }
 982     reconnect_wait(s->reconnect, time_msec());
 983 }
 984
 985 size_t
 986 jsonrpc_session_get_backlog(const struct jsonrpc_session *s)
 987 {
 988     return s->rpc ? jsonrpc_get_backlog(s->rpc) : 0;
 989 }
 990
 991 /* Always returns a pointer to a valid C string, assuming 's' was initialized
 992  * correctly. */
 993 const char *
 994 jsonrpc_session_get_name(const struct jsonrpc_session *s)
 995 {
 996     return reconnect_get_name(s->reconnect);
 997 }
 998
 999 /* Always takes ownership of 'msg', regardless of success. */
1000 int
1001 jsonrpc_session_send(struct jsonrpc_session *s, struct jsonrpc_msg *msg)
1002 {
1003     if (s->rpc) {
1004         return jsonrpc_send(s->rpc, msg);
1005     } else {
1006         jsonrpc_msg_destroy(msg);
1007         return ENOTCONN;
1008     }
1009 }
1010
1011 struct jsonrpc_msg *
1012 jsonrpc_session_recv(struct jsonrpc_session *s)
1013 {
1014     if (s->rpc) {
1015         unsigned int received_bytes;
1016         struct jsonrpc_msg *msg;
1017
1018         received_bytes = jsonrpc_get_received_bytes(s->rpc);
1019         jsonrpc_recv(s->rpc, &msg);
1020         if (received_bytes != jsonrpc_get_received_bytes(s->rpc)) {
1021             /* Data was successfully received.
1022              *
1023              * Previously we only counted receiving a full message as activity,
1024              * but with large messages or a slow connection that policy could
1025              * time out the session mid-message. */
1026             reconnect_activity(s->reconnect, time_msec());
1027         }
1028
1029         if (msg) {
1030             if (msg->type == JSONRPC_REQUEST && !strcmp(msg->method, "echo")) {
1031                 /* Echo request.  Send reply. */
1032                 struct jsonrpc_msg *reply;
1033
1034                 reply = jsonrpc_create_reply(json_clone(msg->params), msg->id);
1035                 jsonrpc_session_send(s, reply);
1036             } else if (msg->type == JSONRPC_REPLY
1037                        && msg->id && msg->id->type == JSON_STRING
1038                        && !strcmp(msg->id->u.string, "echo")) {
1039                 /* It's a reply to our echo request.  Suppress it. */
1040             } else {
1041                 return msg;
1042             }
1043             jsonrpc_msg_destroy(msg);
1044         }
1045     }
1046     return NULL;
1047 }
1048
1049 void
1050 jsonrpc_session_recv_wait(struct jsonrpc_session *s)
1051 {
1052     if (s->rpc) {
1053         jsonrpc_recv_wait(s->rpc);
1054     }
1055 }
1056
1057 bool
1058 jsonrpc_session_is_alive(const struct jsonrpc_session *s)
1059 {
1060     return s->rpc || s->stream || reconnect_get_max_tries(s->reconnect);
1061 }
1062
1063 bool
1064 jsonrpc_session_is_connected(const struct jsonrpc_session *s)
1065 {
1066     return s->rpc != NULL;
1067 }
1068
1069 unsigned int
1070 jsonrpc_session_get_seqno(const struct jsonrpc_session *s)
1071 {
1072     return s->seqno;
1073 }
1074
1075 int
1076 jsonrpc_session_get_status(const struct jsonrpc_session *s)
1077 {
1078     return s && s->rpc ? jsonrpc_get_status(s->rpc) : 0;
1079 }
1080
1081 int
1082 jsonrpc_session_get_last_error(const struct jsonrpc_session *s)
1083 {
1084     return s->last_error;
1085 }
1086
1087 void
1088 jsonrpc_session_get_reconnect_stats(const struct jsonrpc_session *s,
1089                                     struct reconnect_stats *stats)
1090 {
1091     reconnect_get_stats(s->reconnect, time_msec(), stats);
1092 }
1093
1094 void
1095 jsonrpc_session_force_reconnect(struct jsonrpc_session *s)
1096 {
1097     reconnect_force_reconnect(s->reconnect, time_msec());
1098 }
1099
1100 void
1101 jsonrpc_session_set_max_backoff(struct jsonrpc_session *s, int max_backoff)
1102 {
1103     reconnect_set_backoff(s->reconnect, 0, max_backoff);
1104 }
1105
1106 void
1107 jsonrpc_session_set_probe_interval(struct jsonrpc_session *s,
1108                                    int probe_interval)
1109 {
1110     reconnect_set_probe_interval(s->reconnect, probe_interval);
1111 }
1112
1113 void
1114 jsonrpc_session_set_dscp(struct jsonrpc_session *s,
1115                          uint8_t dscp)
1116 {
1117     if (s->dscp != dscp) {
1118         if (s->pstream) {
1119             int error;
1120
1121             error = pstream_set_dscp(s->pstream, dscp);
1122             if (error) {
1123                 VLOG_ERR("%s: failed set_dscp %s",
1124                          reconnect_get_name(s->reconnect),
1125                          ovs_strerror(error));
1126             }
1127             /*
1128              * XXX race window between setting dscp to listening socket
1129              * and accepting socket. accepted socket may have old dscp value.
1130              * Ignore this race window for now.
1131              */
1132         }
1133         s->dscp = dscp;
1134         jsonrpc_session_force_reconnect(s);
1135     }
1136 }