lib/jsonrpc.c

   1 /*
   2  * Copyright (c) 2009, 2010, 2011, 2012, 2013, 2014, 2015 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 "openvswitch/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
  48     /* Output. */
  49     struct ovs_list output;     /* Contains "struct ofpbuf"s. */
  50     size_t output_count;        /* Number of elements in "output". */
  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 struct jsonrpc_msg *jsonrpc_parse_received_message(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 port 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_port(name, OVSDB_PORT, streamp, dscp);
  67 }
  68
  69 /* This is just the same as pstream_open() except that it uses the default
  70  * JSONRPC port if none is specified. */
  71 int
  72 jsonrpc_pstream_open(const char *name, struct pstream **pstreamp, uint8_t dscp)
  73 {
  74     return pstream_open_with_default_port(name, OVSDB_PORT, pstreamp, dscp);
  75 }
  76
  77 /* Returns a new JSON-RPC stream that uses 'stream' for input and output.  The
  78  * new jsonrpc object takes ownership of 'stream'. */
  79 struct jsonrpc *
  80 jsonrpc_open(struct stream *stream)
  81 {
  82     struct jsonrpc *rpc;
  83
  84     ovs_assert(stream != NULL);
  85
  86     rpc = xzalloc(sizeof *rpc);
  87     rpc->name = xstrdup(stream_get_name(stream));
  88     rpc->stream = stream;
  89     byteq_init(&rpc->input, rpc->input_buffer, sizeof rpc->input_buffer);
  90     list_init(&rpc->output);
  91
  92     return rpc;
  93 }
  94
  95 /* Destroys 'rpc', closing the stream on which it is based, and frees its
  96  * memory. */
  97 void
  98 jsonrpc_close(struct jsonrpc *rpc)
  99 {
 100     if (rpc) {
 101         jsonrpc_cleanup(rpc);
 102         free(rpc->name);
 103         free(rpc);
 104     }
 105 }
 106
 107 /* Performs periodic maintenance on 'rpc', such as flushing output buffers. */
 108 void
 109 jsonrpc_run(struct jsonrpc *rpc)
 110 {
 111     if (rpc->status) {
 112         return;
 113     }
 114
 115     stream_run(rpc->stream);
 116     while (!list_is_empty(&rpc->output)) {
 117         struct ofpbuf *buf = ofpbuf_from_list(rpc->output.next);
 118         int retval;
 119
 120         retval = stream_send(rpc->stream, buf->data, buf->size);
 121         if (retval >= 0) {
 122             rpc->backlog -= retval;
 123             ofpbuf_pull(buf, retval);
 124             if (!buf->size) {
 125                 list_remove(&buf->list_node);
 126                 rpc->output_count--;
 127                 ofpbuf_delete(buf);
 128             }
 129         } else {
 130             if (retval != -EAGAIN) {
 131                 VLOG_WARN_RL(&rl, "%s: send error: %s",
 132                              rpc->name, ovs_strerror(-retval));
 133                 jsonrpc_error(rpc, -retval);
 134             }
 135             break;
 136         }
 137     }
 138 }
 139
 140 /* Arranges for the poll loop to wake up when 'rpc' needs to perform
 141  * maintenance activities. */
 142 void
 143 jsonrpc_wait(struct jsonrpc *rpc)
 144 {
 145     if (!rpc->status) {
 146         stream_run_wait(rpc->stream);
 147         if (!list_is_empty(&rpc->output)) {
 148             stream_send_wait(rpc->stream);
 149         }
 150     }
 151 }
 152
 153 /*
 154  * Returns the current status of 'rpc'.  The possible return values are:
 155  * - 0: no error yet
 156  * - >0: errno value
 157  * - EOF: end of file (remote end closed connection; not necessarily an error).
 158  *
 159  * When this functions nonzero, 'rpc' is effectively out of commission.  'rpc'
 160  * will not receive any more messages and any further messages that one
 161  * attempts to send with 'rpc' will be discarded.  The caller can keep 'rpc'
 162  * around as long as it wants, but it's not going to provide any more useful
 163  * services.
 164  */
 165 int
 166 jsonrpc_get_status(const struct jsonrpc *rpc)
 167 {
 168     return rpc->status;
 169 }
 170
 171 /* Returns the number of bytes buffered by 'rpc' to be written to the
 172  * underlying stream.  Always returns 0 if 'rpc' has encountered an error or if
 173  * the remote end closed the connection. */
 174 size_t
 175 jsonrpc_get_backlog(const struct jsonrpc *rpc)
 176 {
 177     return rpc->status ? 0 : rpc->backlog;
 178 }
 179
 180 /* Returns the number of bytes that have been received on 'rpc''s underlying
 181  * stream.  (The value wraps around if it exceeds UINT_MAX.) */
 182 unsigned int
 183 jsonrpc_get_received_bytes(const struct jsonrpc *rpc)
 184 {
 185     return rpc->input.head;
 186 }
 187
 188 /* Returns 'rpc''s name, that is, the name returned by stream_get_name() for
 189  * the stream underlying 'rpc' when 'rpc' was created. */
 190 const char *
 191 jsonrpc_get_name(const struct jsonrpc *rpc)
 192 {
 193     return rpc->name;
 194 }
 195
 196 static void
 197 jsonrpc_log_msg(const struct jsonrpc *rpc, const char *title,
 198                 const struct jsonrpc_msg *msg)
 199 {
 200     if (VLOG_IS_DBG_ENABLED()) {
 201         struct ds s = DS_EMPTY_INITIALIZER;
 202         if (msg->method) {
 203             ds_put_format(&s, ", method=\"%s\"", msg->method);
 204         }
 205         if (msg->params) {
 206             ds_put_cstr(&s, ", params=");
 207             json_to_ds(msg->params, 0, &s);
 208         }
 209         if (msg->result) {
 210             ds_put_cstr(&s, ", result=");
 211             json_to_ds(msg->result, 0, &s);
 212         }
 213         if (msg->error) {
 214             ds_put_cstr(&s, ", error=");
 215             json_to_ds(msg->error, 0, &s);
 216         }
 217         if (msg->id) {
 218             ds_put_cstr(&s, ", id=");
 219             json_to_ds(msg->id, 0, &s);
 220         }
 221         VLOG_DBG("%s: %s %s%s", rpc->name, title,
 222                  jsonrpc_msg_type_to_string(msg->type), ds_cstr(&s));
 223         ds_destroy(&s);
 224     }
 225 }
 226
 227 /* Schedules 'msg' to be sent on 'rpc' and returns 'rpc''s status (as with
 228  * jsonrpc_get_status()).
 229  *
 230  * If 'msg' cannot be sent immediately, it is appended to a buffer.  The caller
 231  * is responsible for ensuring that the amount of buffered data is somehow
 232  * limited.  (jsonrpc_get_backlog() returns the amount of data currently
 233  * buffered in 'rpc'.)
 234  *
 235  * Always takes ownership of 'msg', regardless of success. */
 236 int
 237 jsonrpc_send(struct jsonrpc *rpc, struct jsonrpc_msg *msg)
 238 {
 239     struct ofpbuf *buf;
 240     struct json *json;
 241     struct ds ds = DS_EMPTY_INITIALIZER;
 242     size_t length;
 243     char *s;
 244
 245     if (rpc->status) {
 246         jsonrpc_msg_destroy(msg);
 247         return rpc->status;
 248     }
 249
 250     jsonrpc_log_msg(rpc, "send", msg);
 251
 252     json = jsonrpc_msg_to_json(msg);
 253     json_to_ds(json, 0, &ds);
 254     length = ds.length;
 255     s = ds_steal_cstr(&ds);
 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->output_count++;
 263     rpc->backlog += length;
 264
 265     if (rpc->output_count >= 50) {
 266         VLOG_INFO_RL(&rl, "excessive sending backlog, jsonrpc: %s, num of"
 267                      " msgs: %"PRIuSIZE", backlog: %"PRIuSIZE".", rpc->name,
 268                      rpc->output_count, rpc->backlog);
 269     }
 270
 271     if (rpc->backlog == length) {
 272         jsonrpc_run(rpc);
 273     }
 274     return rpc->status;
 275 }
 276
 277 /* Attempts to receive a message from 'rpc'.
 278  *
 279  * If successful, stores the received message in '*msgp' and returns 0.  The
 280  * caller takes ownership of '*msgp' and must eventually destroy it with
 281  * jsonrpc_msg_destroy().
 282  *
 283  * Otherwise, stores NULL in '*msgp' and returns one of the following:
 284  *
 285  *   - EAGAIN: No message has been received.
 286  *
 287  *   - EOF: The remote end closed the connection gracefully.
 288  *
 289  *   - Otherwise an errno value that represents a JSON-RPC protocol violation
 290  *     or another error fatal to the connection.  'rpc' will not send or
 291  *     receive any more messages.
 292  */
 293 int
 294 jsonrpc_recv(struct jsonrpc *rpc, struct jsonrpc_msg **msgp)
 295 {
 296     int i;
 297
 298     *msgp = NULL;
 299     if (rpc->status) {
 300         return rpc->status;
 301     }
 302
 303     for (i = 0; i < 50; i++) {
 304         size_t n, used;
 305
 306         /* Fill our input buffer if it's empty. */
 307         if (byteq_is_empty(&rpc->input)) {
 308             size_t chunk;
 309             int retval;
 310
 311             chunk = byteq_headroom(&rpc->input);
 312             retval = stream_recv(rpc->stream, byteq_head(&rpc->input), chunk);
 313             if (retval < 0) {
 314                 if (retval == -EAGAIN) {
 315                     return EAGAIN;
 316                 } else {
 317                     VLOG_WARN_RL(&rl, "%s: receive error: %s",
 318                                  rpc->name, ovs_strerror(-retval));
 319                     jsonrpc_error(rpc, -retval);
 320                     return rpc->status;
 321                 }
 322             } else if (retval == 0) {
 323                 jsonrpc_error(rpc, EOF);
 324                 return EOF;
 325             }
 326             byteq_advance_head(&rpc->input, retval);
 327         }
 328
 329         /* We have some input.  Feed it into the JSON parser. */
 330         if (!rpc->parser) {
 331             rpc->parser = json_parser_create(0);
 332         }
 333         n = byteq_tailroom(&rpc->input);
 334         used = json_parser_feed(rpc->parser,
 335                                 (char *) byteq_tail(&rpc->input), n);
 336         byteq_advance_tail(&rpc->input, used);
 337
 338         /* If we have complete JSON, attempt to parse it as JSON-RPC. */
 339         if (json_parser_is_done(rpc->parser)) {
 340             *msgp = jsonrpc_parse_received_message(rpc);
 341             if (*msgp) {
 342                 return 0;
 343             }
 344
 345             if (rpc->status) {
 346                 const struct byteq *q = &rpc->input;
 347                 if (q->head <= q->size) {
 348                     stream_report_content(q->buffer, q->head, STREAM_JSONRPC,
 349                                           THIS_MODULE, rpc->name);
 350                 }
 351                 return rpc->status;
 352             }
 353         }
 354     }
 355
 356     return EAGAIN;
 357 }
 358
 359 /* Causes the poll loop to wake up when jsonrpc_recv() may return a value other
 360  * than EAGAIN. */
 361 void
 362 jsonrpc_recv_wait(struct jsonrpc *rpc)
 363 {
 364     if (rpc->status || !byteq_is_empty(&rpc->input)) {
 365         poll_immediate_wake_at(rpc->name);
 366     } else {
 367         stream_recv_wait(rpc->stream);
 368     }
 369 }
 370
 371 /* Sends 'msg' on 'rpc' and waits for it to be successfully queued to the
 372  * underlying stream.  Returns 0 if 'msg' was sent successfully, otherwise a
 373  * status value (see jsonrpc_get_status()).
 374  *
 375  * Always takes ownership of 'msg', regardless of success. */
 376 int
 377 jsonrpc_send_block(struct jsonrpc *rpc, struct jsonrpc_msg *msg)
 378 {
 379     int error;
 380
 381     fatal_signal_run();
 382
 383     error = jsonrpc_send(rpc, msg);
 384     if (error) {
 385         return error;
 386     }
 387
 388     for (;;) {
 389         jsonrpc_run(rpc);
 390         if (list_is_empty(&rpc->output) || rpc->status) {
 391             return rpc->status;
 392         }
 393         jsonrpc_wait(rpc);
 394         poll_block();
 395     }
 396 }
 397
 398 /* Waits for a message to be received on 'rpc'.  Same semantics as
 399  * jsonrpc_recv() except that EAGAIN will never be returned. */
 400 int
 401 jsonrpc_recv_block(struct jsonrpc *rpc, struct jsonrpc_msg **msgp)
 402 {
 403     for (;;) {
 404         int error = jsonrpc_recv(rpc, msgp);
 405         if (error != EAGAIN) {
 406             fatal_signal_run();
 407             return error;
 408         }
 409
 410         jsonrpc_run(rpc);
 411         jsonrpc_wait(rpc);
 412         jsonrpc_recv_wait(rpc);
 413         poll_block();
 414     }
 415 }
 416
 417 /* Sends 'request' to 'rpc' then waits for a reply.  The return value is 0 if
 418  * successful, in which case '*replyp' is set to the reply, which the caller
 419  * must eventually free with jsonrpc_msg_destroy().  Otherwise returns a status
 420  * value (see jsonrpc_get_status()).
 421  *
 422  * Discards any message received on 'rpc' that is not a reply to 'request'
 423  * (based on message id).
 424  *
 425  * Always takes ownership of 'request', regardless of success. */
 426 int
 427 jsonrpc_transact_block(struct jsonrpc *rpc, struct jsonrpc_msg *request,
 428                        struct jsonrpc_msg **replyp)
 429 {
 430     struct jsonrpc_msg *reply = NULL;
 431     struct json *id;
 432     int error;
 433
 434     id = json_clone(request->id);
 435     error = jsonrpc_send_block(rpc, request);
 436     if (!error) {
 437         for (;;) {
 438             error = jsonrpc_recv_block(rpc, &reply);
 439             if (error) {
 440                 break;
 441             }
 442             if ((reply->type == JSONRPC_REPLY || reply->type == JSONRPC_ERROR)
 443                 && json_equal(id, reply->id)) {
 444                 break;
 445             }
 446             jsonrpc_msg_destroy(reply);
 447         }
 448     }
 449     *replyp = error ? NULL : reply;
 450     json_destroy(id);
 451     return error;
 452 }
 453
 454 /* Attempts to parse the content of 'rpc->parser' (which is complete JSON) as a
 455  * JSON-RPC message.  If successful, returns the JSON-RPC message.  On failure,
 456  * signals an error on 'rpc' with jsonrpc_error() and returns NULL. */
 457 static struct jsonrpc_msg *
 458 jsonrpc_parse_received_message(struct jsonrpc *rpc)
 459 {
 460     struct jsonrpc_msg *msg;
 461     struct json *json;
 462     char *error;
 463
 464     json = json_parser_finish(rpc->parser);
 465     rpc->parser = NULL;
 466     if (json->type == JSON_STRING) {
 467         VLOG_WARN_RL(&rl, "%s: error parsing stream: %s",
 468                      rpc->name, json_string(json));
 469         jsonrpc_error(rpc, EPROTO);
 470         json_destroy(json);
 471         return NULL;
 472     }
 473
 474     error = jsonrpc_msg_from_json(json, &msg);
 475     if (error) {
 476         VLOG_WARN_RL(&rl, "%s: received bad JSON-RPC message: %s",
 477                      rpc->name, error);
 478         free(error);
 479         jsonrpc_error(rpc, EPROTO);
 480         return NULL;
 481     }
 482
 483     jsonrpc_log_msg(rpc, "received", msg);
 484     return msg;
 485 }
 486
 487 static void
 488 jsonrpc_error(struct jsonrpc *rpc, int error)
 489 {
 490     ovs_assert(error);
 491     if (!rpc->status) {
 492         rpc->status = error;
 493         jsonrpc_cleanup(rpc);
 494     }
 495 }
 496
 497 static void
 498 jsonrpc_cleanup(struct jsonrpc *rpc)
 499 {
 500     stream_close(rpc->stream);
 501     rpc->stream = NULL;
 502
 503     json_parser_abort(rpc->parser);
 504     rpc->parser = NULL;
 505
 506     ofpbuf_list_delete(&rpc->output);
 507     rpc->backlog = 0;
 508     rpc->output_count = 0;
 509 }
 510 \f
 511 static struct jsonrpc_msg *
 512 jsonrpc_create(enum jsonrpc_msg_type type, const char *method,
 513                 struct json *params, struct json *result, struct json *error,
 514                 struct json *id)
 515 {
 516     struct jsonrpc_msg *msg = xmalloc(sizeof *msg);
 517     msg->type = type;
 518     msg->method = method ? xstrdup(method) : NULL;
 519     msg->params = params;
 520     msg->result = result;
 521     msg->error = error;
 522     msg->id = id;
 523     return msg;
 524 }
 525
 526 static struct json *
 527 jsonrpc_create_id(void)
 528 {
 529     static atomic_count next_id = ATOMIC_COUNT_INIT(0);
 530     unsigned int id;
 531
 532     id = atomic_count_inc(&next_id);
 533     return json_integer_create(id);
 534 }
 535
 536 struct jsonrpc_msg *
 537 jsonrpc_create_request(const char *method, struct json *params,
 538                        struct json **idp)
 539 {
 540     struct json *id = jsonrpc_create_id();
 541     if (idp) {
 542         *idp = json_clone(id);
 543     }
 544     return jsonrpc_create(JSONRPC_REQUEST, method, params, NULL, NULL, id);
 545 }
 546
 547 struct jsonrpc_msg *
 548 jsonrpc_create_notify(const char *method, struct json *params)
 549 {
 550     return jsonrpc_create(JSONRPC_NOTIFY, method, params, NULL, NULL, NULL);
 551 }
 552
 553 struct jsonrpc_msg *
 554 jsonrpc_create_reply(struct json *result, const struct json *id)
 555 {
 556     return jsonrpc_create(JSONRPC_REPLY, NULL, NULL, result, NULL,
 557                            json_clone(id));
 558 }
 559
 560 struct jsonrpc_msg *
 561 jsonrpc_create_error(struct json *error, const struct json *id)
 562 {
 563     return jsonrpc_create(JSONRPC_REPLY, NULL, NULL, NULL, error,
 564                            json_clone(id));
 565 }
 566
 567 const char *
 568 jsonrpc_msg_type_to_string(enum jsonrpc_msg_type type)
 569 {
 570     switch (type) {
 571     case JSONRPC_REQUEST:
 572         return "request";
 573
 574     case JSONRPC_NOTIFY:
 575         return "notification";
 576
 577     case JSONRPC_REPLY:
 578         return "reply";
 579
 580     case JSONRPC_ERROR:
 581         return "error";
 582     }
 583     return "(null)";
 584 }
 585
 586 char *
 587 jsonrpc_msg_is_valid(const struct jsonrpc_msg *m)
 588 {
 589     const char *type_name;
 590     unsigned int pattern;
 591
 592     if (m->params && m->params->type != JSON_ARRAY) {
 593         return xstrdup("\"params\" must be JSON array");
 594     }
 595
 596     switch (m->type) {
 597     case JSONRPC_REQUEST:
 598         pattern = 0x11001;
 599         break;
 600
 601     case JSONRPC_NOTIFY:
 602         pattern = 0x11000;
 603         break;
 604
 605     case JSONRPC_REPLY:
 606         pattern = 0x00101;
 607         break;
 608
 609     case JSONRPC_ERROR:
 610         pattern = 0x00011;
 611         break;
 612
 613     default:
 614         return xasprintf("invalid JSON-RPC message type %d", m->type);
 615     }
 616
 617     type_name = jsonrpc_msg_type_to_string(m->type);
 618     if ((m->method != NULL) != ((pattern & 0x10000) != 0)) {
 619         return xasprintf("%s must%s have \"method\"",
 620                          type_name, (pattern & 0x10000) ? "" : " not");
 621
 622     }
 623     if ((m->params != NULL) != ((pattern & 0x1000) != 0)) {
 624         return xasprintf("%s must%s have \"params\"",
 625                          type_name, (pattern & 0x1000) ? "" : " not");
 626
 627     }
 628     if ((m->result != NULL) != ((pattern & 0x100) != 0)) {
 629         return xasprintf("%s must%s have \"result\"",
 630                          type_name, (pattern & 0x100) ? "" : " not");
 631
 632     }
 633     if ((m->error != NULL) != ((pattern & 0x10) != 0)) {
 634         return xasprintf("%s must%s have \"error\"",
 635                          type_name, (pattern & 0x10) ? "" : " not");
 636
 637     }
 638     if ((m->id != NULL) != ((pattern & 0x1) != 0)) {
 639         return xasprintf("%s must%s have \"id\"",
 640                          type_name, (pattern & 0x1) ? "" : " not");
 641
 642     }
 643     return NULL;
 644 }
 645
 646 void
 647 jsonrpc_msg_destroy(struct jsonrpc_msg *m)
 648 {
 649     if (m) {
 650         free(m->method);
 651         json_destroy(m->params);
 652         json_destroy(m->result);
 653         json_destroy(m->error);
 654         json_destroy(m->id);
 655         free(m);
 656     }
 657 }
 658
 659 static struct json *
 660 null_from_json_null(struct json *json)
 661 {
 662     if (json && json->type == JSON_NULL) {
 663         json_destroy(json);
 664         return NULL;
 665     }
 666     return json;
 667 }
 668
 669 char *
 670 jsonrpc_msg_from_json(struct json *json, struct jsonrpc_msg **msgp)
 671 {
 672     struct json *method = NULL;
 673     struct jsonrpc_msg *msg = NULL;
 674     struct shash *object;
 675     char *error;
 676
 677     if (json->type != JSON_OBJECT) {
 678         error = xstrdup("message is not a JSON object");
 679         goto exit;
 680     }
 681     object = json_object(json);
 682
 683     method = shash_find_and_delete(object, "method");
 684     if (method && method->type != JSON_STRING) {
 685         error = xstrdup("method is not a JSON string");
 686         goto exit;
 687     }
 688
 689     msg = xzalloc(sizeof *msg);
 690     msg->method = method ? xstrdup(method->u.string) : NULL;
 691     msg->params = null_from_json_null(shash_find_and_delete(object, "params"));
 692     msg->result = null_from_json_null(shash_find_and_delete(object, "result"));
 693     msg->error = null_from_json_null(shash_find_and_delete(object, "error"));
 694     msg->id = null_from_json_null(shash_find_and_delete(object, "id"));
 695     msg->type = (msg->result ? JSONRPC_REPLY
 696                  : msg->error ? JSONRPC_ERROR
 697                  : msg->id ? JSONRPC_REQUEST
 698                  : JSONRPC_NOTIFY);
 699     if (!shash_is_empty(object)) {
 700         error = xasprintf("message has unexpected member \"%s\"",
 701                           shash_first(object)->name);
 702         goto exit;
 703     }
 704     error = jsonrpc_msg_is_valid(msg);
 705     if (error) {
 706         goto exit;
 707     }
 708
 709 exit:
 710     json_destroy(method);
 711     json_destroy(json);
 712     if (error) {
 713         jsonrpc_msg_destroy(msg);
 714         msg = NULL;
 715     }
 716     *msgp = msg;
 717     return error;
 718 }
 719
 720 struct json *
 721 jsonrpc_msg_to_json(struct jsonrpc_msg *m)
 722 {
 723     struct json *json = json_object_create();
 724
 725     if (m->method) {
 726         json_object_put(json, "method", json_string_create_nocopy(m->method));
 727     }
 728
 729     if (m->params) {
 730         json_object_put(json, "params", m->params);
 731     }
 732
 733     if (m->result) {
 734         json_object_put(json, "result", m->result);
 735     } else if (m->type == JSONRPC_ERROR) {
 736         json_object_put(json, "result", json_null_create());
 737     }
 738
 739     if (m->error) {
 740         json_object_put(json, "error", m->error);
 741     } else if (m->type == JSONRPC_REPLY) {
 742         json_object_put(json, "error", json_null_create());
 743     }
 744
 745     if (m->id) {
 746         json_object_put(json, "id", m->id);
 747     } else if (m->type == JSONRPC_NOTIFY) {
 748         json_object_put(json, "id", json_null_create());
 749     }
 750
 751     free(m);
 752
 753     return json;
 754 }
 755 \f
 756 /* A JSON-RPC session with reconnection. */
 757
 758 struct jsonrpc_session {
 759     struct reconnect *reconnect;
 760     struct jsonrpc *rpc;
 761     struct stream *stream;
 762     struct pstream *pstream;
 763     int last_error;
 764     unsigned int seqno;
 765     uint8_t dscp;
 766 };
 767
 768 /* Creates and returns a jsonrpc_session to 'name', which should be a string
 769  * acceptable to stream_open() or pstream_open().
 770  *
 771  * If 'name' is an active connection method, e.g. "tcp:127.1.2.3", the new
 772  * jsonrpc_session connects to 'name'.  If 'retry' is true, then the new
 773  * session connects and reconnects to 'name', with backoff.  If 'retry' is
 774  * false, the new session will only try to connect once and after a connection
 775  * failure or a disconnection jsonrpc_session_is_alive() will return false for
 776  * the new session.
 777  *
 778  * If 'name' is a passive connection method, e.g. "ptcp:", the new
 779  * jsonrpc_session listens for connections to 'name'.  It maintains at most one
 780  * connection at any given time.  Any new connection causes the previous one
 781  * (if any) to be dropped. */
 782 struct jsonrpc_session *
 783 jsonrpc_session_open(const char *name, bool retry)
 784 {
 785     struct jsonrpc_session *s;
 786
 787     s = xmalloc(sizeof *s);
 788     s->reconnect = reconnect_create(time_msec());
 789     reconnect_set_name(s->reconnect, name);
 790     reconnect_enable(s->reconnect, time_msec());
 791     s->rpc = NULL;
 792     s->stream = NULL;
 793     s->pstream = NULL;
 794     s->seqno = 0;
 795     s->dscp = 0;
 796     s->last_error = 0;
 797
 798     if (!pstream_verify_name(name)) {
 799         reconnect_set_passive(s->reconnect, true, time_msec());
 800     } else if (!retry) {
 801         reconnect_set_max_tries(s->reconnect, 1);
 802         reconnect_set_backoff(s->reconnect, INT_MAX, INT_MAX);
 803     }
 804
 805     if (!stream_or_pstream_needs_probes(name)) {
 806         reconnect_set_probe_interval(s->reconnect, 0);
 807     }
 808
 809     return s;
 810 }
 811
 812 /* Creates and returns a jsonrpc_session that is initially connected to
 813  * 'jsonrpc'.  If the connection is dropped, it will not be reconnected.
 814  *
 815  * On the assumption that such connections are likely to be short-lived
 816  * (e.g. from ovs-vsctl), informational logging for them is suppressed. */
 817 struct jsonrpc_session *
 818 jsonrpc_session_open_unreliably(struct jsonrpc *jsonrpc, uint8_t dscp)
 819 {
 820     struct jsonrpc_session *s;
 821
 822     s = xmalloc(sizeof *s);
 823     s->reconnect = reconnect_create(time_msec());
 824     reconnect_set_quiet(s->reconnect, true);
 825     reconnect_set_name(s->reconnect, jsonrpc_get_name(jsonrpc));
 826     reconnect_set_max_tries(s->reconnect, 0);
 827     reconnect_connected(s->reconnect, time_msec());
 828     s->dscp = dscp;
 829     s->rpc = jsonrpc;
 830     s->stream = NULL;
 831     s->pstream = NULL;
 832     s->seqno = 0;
 833
 834     return s;
 835 }
 836
 837 void
 838 jsonrpc_session_close(struct jsonrpc_session *s)
 839 {
 840     if (s) {
 841         jsonrpc_close(s->rpc);
 842         reconnect_destroy(s->reconnect);
 843         stream_close(s->stream);
 844         pstream_close(s->pstream);
 845         free(s);
 846     }
 847 }
 848
 849 static void
 850 jsonrpc_session_disconnect(struct jsonrpc_session *s)
 851 {
 852     if (s->rpc) {
 853         jsonrpc_error(s->rpc, EOF);
 854         jsonrpc_close(s->rpc);
 855         s->rpc = NULL;
 856         s->seqno++;
 857     } else if (s->stream) {
 858         stream_close(s->stream);
 859         s->stream = NULL;
 860         s->seqno++;
 861     }
 862 }
 863
 864 static void
 865 jsonrpc_session_connect(struct jsonrpc_session *s)
 866 {
 867     const char *name = reconnect_get_name(s->reconnect);
 868     int error;
 869
 870     jsonrpc_session_disconnect(s);
 871     if (!reconnect_is_passive(s->reconnect)) {
 872         error = jsonrpc_stream_open(name, &s->stream, s->dscp);
 873         if (!error) {
 874             reconnect_connecting(s->reconnect, time_msec());
 875         } else {
 876             s->last_error = error;
 877         }
 878     } else {
 879         error = s->pstream ? 0 : jsonrpc_pstream_open(name, &s->pstream,
 880                                                       s->dscp);
 881         if (!error) {
 882             reconnect_listening(s->reconnect, time_msec());
 883         }
 884     }
 885
 886     if (error) {
 887         reconnect_connect_failed(s->reconnect, time_msec(), error);
 888     }
 889     s->seqno++;
 890 }
 891
 892 void
 893 jsonrpc_session_run(struct jsonrpc_session *s)
 894 {
 895     if (s->pstream) {
 896         struct stream *stream;
 897         int error;
 898
 899         error = pstream_accept(s->pstream, &stream);
 900         if (!error) {
 901             if (s->rpc || s->stream) {
 902                 VLOG_INFO_RL(&rl,
 903                              "%s: new connection replacing active connection",
 904                              reconnect_get_name(s->reconnect));
 905                 jsonrpc_session_disconnect(s);
 906             }
 907             reconnect_connected(s->reconnect, time_msec());
 908             s->rpc = jsonrpc_open(stream);
 909         } else if (error != EAGAIN) {
 910             reconnect_listen_error(s->reconnect, time_msec(), error);
 911             pstream_close(s->pstream);
 912             s->pstream = NULL;
 913         }
 914     }
 915
 916     if (s->rpc) {
 917         size_t backlog;
 918         int error;
 919
 920         backlog = jsonrpc_get_backlog(s->rpc);
 921         jsonrpc_run(s->rpc);
 922         if (jsonrpc_get_backlog(s->rpc) < backlog) {
 923             /* Data previously caught in a queue was successfully sent (or
 924              * there's an error, which we'll catch below.)
 925              *
 926              * We don't count data that is successfully sent immediately as
 927              * activity, because there's a lot of queuing downstream from us,
 928              * which means that we can push a lot of data into a connection
 929              * that has stalled and won't ever recover.
 930              */
 931             reconnect_activity(s->reconnect, time_msec());
 932         }
 933
 934         error = jsonrpc_get_status(s->rpc);
 935         if (error) {
 936             reconnect_disconnected(s->reconnect, time_msec(), error);
 937             jsonrpc_session_disconnect(s);
 938             s->last_error = error;
 939         }
 940     } else if (s->stream) {
 941         int error;
 942
 943         stream_run(s->stream);
 944         error = stream_connect(s->stream);
 945         if (!error) {
 946             reconnect_connected(s->reconnect, time_msec());
 947             s->rpc = jsonrpc_open(s->stream);
 948             s->stream = NULL;
 949         } else if (error != EAGAIN) {
 950             reconnect_connect_failed(s->reconnect, time_msec(), error);
 951             stream_close(s->stream);
 952             s->stream = NULL;
 953             s->last_error = error;
 954         }
 955     }
 956
 957     switch (reconnect_run(s->reconnect, time_msec())) {
 958     case RECONNECT_CONNECT:
 959         jsonrpc_session_connect(s);
 960         break;
 961
 962     case RECONNECT_DISCONNECT:
 963         reconnect_disconnected(s->reconnect, time_msec(), 0);
 964         jsonrpc_session_disconnect(s);
 965         break;
 966
 967     case RECONNECT_PROBE:
 968         if (s->rpc) {
 969             struct json *params;
 970             struct jsonrpc_msg *request;
 971
 972             params = json_array_create_empty();
 973             request = jsonrpc_create_request("echo", params, NULL);
 974             json_destroy(request->id);
 975             request->id = json_string_create("echo");
 976             jsonrpc_send(s->rpc, request);
 977         }
 978         break;
 979     }
 980 }
 981
 982 void
 983 jsonrpc_session_wait(struct jsonrpc_session *s)
 984 {
 985     if (s->rpc) {
 986         jsonrpc_wait(s->rpc);
 987     } else if (s->stream) {
 988         stream_run_wait(s->stream);
 989         stream_connect_wait(s->stream);
 990     }
 991     if (s->pstream) {
 992         pstream_wait(s->pstream);
 993     }
 994     reconnect_wait(s->reconnect, time_msec());
 995 }
 996
 997 size_t
 998 jsonrpc_session_get_backlog(const struct jsonrpc_session *s)
 999 {
1000     return s->rpc ? jsonrpc_get_backlog(s->rpc) : 0;
1001 }
1002
1003 /* Always returns a pointer to a valid C string, assuming 's' was initialized
1004  * correctly. */
1005 const char *
1006 jsonrpc_session_get_name(const struct jsonrpc_session *s)
1007 {
1008     return reconnect_get_name(s->reconnect);
1009 }
1010
1011 /* Always takes ownership of 'msg', regardless of success. */
1012 int
1013 jsonrpc_session_send(struct jsonrpc_session *s, struct jsonrpc_msg *msg)
1014 {
1015     if (s->rpc) {
1016         return jsonrpc_send(s->rpc, msg);
1017     } else {
1018         jsonrpc_msg_destroy(msg);
1019         return ENOTCONN;
1020     }
1021 }
1022
1023 struct jsonrpc_msg *
1024 jsonrpc_session_recv(struct jsonrpc_session *s)
1025 {
1026     if (s->rpc) {
1027         unsigned int received_bytes;
1028         struct jsonrpc_msg *msg;
1029
1030         received_bytes = jsonrpc_get_received_bytes(s->rpc);
1031         jsonrpc_recv(s->rpc, &msg);
1032         if (received_bytes != jsonrpc_get_received_bytes(s->rpc)) {
1033             /* Data was successfully received.
1034              *
1035              * Previously we only counted receiving a full message as activity,
1036              * but with large messages or a slow connection that policy could
1037              * time out the session mid-message. */
1038             reconnect_activity(s->reconnect, time_msec());
1039         }
1040
1041         if (msg) {
1042             if (msg->type == JSONRPC_REQUEST && !strcmp(msg->method, "echo")) {
1043                 /* Echo request.  Send reply. */
1044                 struct jsonrpc_msg *reply;
1045
1046                 reply = jsonrpc_create_reply(json_clone(msg->params), msg->id);
1047                 jsonrpc_session_send(s, reply);
1048             } else if (msg->type == JSONRPC_REPLY
1049                        && msg->id && msg->id->type == JSON_STRING
1050                        && !strcmp(msg->id->u.string, "echo")) {
1051                 /* It's a reply to our echo request.  Suppress it. */
1052             } else {
1053                 return msg;
1054             }
1055             jsonrpc_msg_destroy(msg);
1056         }
1057     }
1058     return NULL;
1059 }
1060
1061 void
1062 jsonrpc_session_recv_wait(struct jsonrpc_session *s)
1063 {
1064     if (s->rpc) {
1065         jsonrpc_recv_wait(s->rpc);
1066     }
1067 }
1068
1069 /* Returns true if 's' is currently connected or trying to connect. */
1070 bool
1071 jsonrpc_session_is_alive(const struct jsonrpc_session *s)
1072 {
1073     return s->rpc || s->stream || reconnect_get_max_tries(s->reconnect);
1074 }
1075
1076 /* Returns true if 's' is currently connected. */
1077 bool
1078 jsonrpc_session_is_connected(const struct jsonrpc_session *s)
1079 {
1080     return s->rpc != NULL;
1081 }
1082
1083 /* Returns a sequence number for 's'.  The sequence number increments every
1084  * time 's' connects or disconnects.  Thus, a caller can use the change (or
1085  * lack of change) in the sequence number to figure out whether the underlying
1086  * connection is the same as before. */
1087 unsigned int
1088 jsonrpc_session_get_seqno(const struct jsonrpc_session *s)
1089 {
1090     return s->seqno;
1091 }
1092
1093 /* Returns the current status of 's'.  If 's' is NULL or is disconnected, this
1094  * is 0, otherwise it is the status of the connection, as reported by
1095  * jsonrpc_get_status(). */
1096 int
1097 jsonrpc_session_get_status(const struct jsonrpc_session *s)
1098 {
1099     return s && s->rpc ? jsonrpc_get_status(s->rpc) : 0;
1100 }
1101
1102 /* Returns the last error reported on a connection by 's'.  The return value is
1103  * 0 only if no connection made by 's' has ever encountered an error.  See
1104  * jsonrpc_get_status() for return value interpretation. */
1105 int
1106 jsonrpc_session_get_last_error(const struct jsonrpc_session *s)
1107 {
1108     return s->last_error;
1109 }
1110
1111 /* Populates 'stats' with statistics from 's'. */
1112 void
1113 jsonrpc_session_get_reconnect_stats(const struct jsonrpc_session *s,
1114                                     struct reconnect_stats *stats)
1115 {
1116     reconnect_get_stats(s->reconnect, time_msec(), stats);
1117 }
1118
1119 /* Enables 's' to reconnect to the peer if the connection drops. */
1120 void
1121 jsonrpc_session_enable_reconnect(struct jsonrpc_session *s)
1122 {
1123     reconnect_set_max_tries(s->reconnect, UINT_MAX);
1124     reconnect_set_backoff(s->reconnect, RECONNECT_DEFAULT_MIN_BACKOFF,
1125                           RECONNECT_DEFAULT_MAX_BACKOFF);
1126 }
1127
1128 /* Forces 's' to drop its connection (if any) and reconnect. */
1129 void
1130 jsonrpc_session_force_reconnect(struct jsonrpc_session *s)
1131 {
1132     reconnect_force_reconnect(s->reconnect, time_msec());
1133 }
1134
1135 /* Sets 'max_backoff' as the maximum time, in milliseconds, to wait after a
1136  * connection attempt fails before attempting to connect again. */
1137 void
1138 jsonrpc_session_set_max_backoff(struct jsonrpc_session *s, int max_backoff)
1139 {
1140     reconnect_set_backoff(s->reconnect, 0, max_backoff);
1141 }
1142
1143 /* Sets the "probe interval" for 's' to 'probe_interval', in milliseconds.  If
1144  * this is zero, it disables the connection keepalive feature.  Otherwise, if
1145  * 's' is idle for 'probe_interval' milliseconds then 's' will send an echo
1146  * request and, if no reply is received within an additional 'probe_interval'
1147  * milliseconds, close the connection (then reconnect, if that feature is
1148  * enabled). */
1149 void
1150 jsonrpc_session_set_probe_interval(struct jsonrpc_session *s,
1151                                    int probe_interval)
1152 {
1153     reconnect_set_probe_interval(s->reconnect, probe_interval);
1154 }
1155
1156 /* Sets the DSCP value used for 's''s connection to 'dscp'.  If this is
1157  * different from the DSCP value currently in use then the connection is closed
1158  * and reconnected. */
1159 void
1160 jsonrpc_session_set_dscp(struct jsonrpc_session *s, uint8_t dscp)
1161 {
1162     if (s->dscp != dscp) {
1163         pstream_close(s->pstream);
1164         s->pstream = NULL;
1165
1166         s->dscp = dscp;
1167         jsonrpc_session_force_reconnect(s);
1168     }
1169 }