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     size_t length;
 242     char *s;
 243
 244     if (rpc->status) {
 245         jsonrpc_msg_destroy(msg);
 246         return rpc->status;
 247     }
 248
 249     jsonrpc_log_msg(rpc, "send", msg);
 250
 251     json = jsonrpc_msg_to_json(msg);
 252     s = json_to_string(json, 0);
 253     length = strlen(s);
 254     json_destroy(json);
 255
 256     buf = xmalloc(sizeof *buf);
 257     ofpbuf_use(buf, s, length);
 258     buf->size = length;
 259     list_push_back(&rpc->output, &buf->list_node);
 260     rpc->output_count++;
 261     rpc->backlog += length;
 262
 263     if (rpc->output_count >= 50) {
 264         VLOG_INFO_RL(&rl, "excessive sending backlog, jsonrpc: %s, num of"
 265                      " msgs: %"PRIuSIZE", backlog: %"PRIuSIZE".", rpc->name,
 266                      rpc->output_count, rpc->backlog);
 267     }
 268
 269     if (rpc->backlog == length) {
 270         jsonrpc_run(rpc);
 271     }
 272     return rpc->status;
 273 }
 274
 275 /* Attempts to receive a message from 'rpc'.
 276  *
 277  * If successful, stores the received message in '*msgp' and returns 0.  The
 278  * caller takes ownership of '*msgp' and must eventually destroy it with
 279  * jsonrpc_msg_destroy().
 280  *
 281  * Otherwise, stores NULL in '*msgp' and returns one of the following:
 282  *
 283  *   - EAGAIN: No message has been received.
 284  *
 285  *   - EOF: The remote end closed the connection gracefully.
 286  *
 287  *   - Otherwise an errno value that represents a JSON-RPC protocol violation
 288  *     or another error fatal to the connection.  'rpc' will not send or
 289  *     receive any more messages.
 290  */
 291 int
 292 jsonrpc_recv(struct jsonrpc *rpc, struct jsonrpc_msg **msgp)
 293 {
 294     int i;
 295
 296     *msgp = NULL;
 297     if (rpc->status) {
 298         return rpc->status;
 299     }
 300
 301     for (i = 0; i < 50; i++) {
 302         size_t n, used;
 303
 304         /* Fill our input buffer if it's empty. */
 305         if (byteq_is_empty(&rpc->input)) {
 306             size_t chunk;
 307             int retval;
 308
 309             chunk = byteq_headroom(&rpc->input);
 310             retval = stream_recv(rpc->stream, byteq_head(&rpc->input), chunk);
 311             if (retval < 0) {
 312                 if (retval == -EAGAIN) {
 313                     return EAGAIN;
 314                 } else {
 315                     VLOG_WARN_RL(&rl, "%s: receive error: %s",
 316                                  rpc->name, ovs_strerror(-retval));
 317                     jsonrpc_error(rpc, -retval);
 318                     return rpc->status;
 319                 }
 320             } else if (retval == 0) {
 321                 jsonrpc_error(rpc, EOF);
 322                 return EOF;
 323             }
 324             byteq_advance_head(&rpc->input, retval);
 325         }
 326
 327         /* We have some input.  Feed it into the JSON parser. */
 328         if (!rpc->parser) {
 329             rpc->parser = json_parser_create(0);
 330         }
 331         n = byteq_tailroom(&rpc->input);
 332         used = json_parser_feed(rpc->parser,
 333                                 (char *) byteq_tail(&rpc->input), n);
 334         byteq_advance_tail(&rpc->input, used);
 335
 336         /* If we have complete JSON, attempt to parse it as JSON-RPC. */
 337         if (json_parser_is_done(rpc->parser)) {
 338             *msgp = jsonrpc_parse_received_message(rpc);
 339             if (*msgp) {
 340                 return 0;
 341             }
 342
 343             if (rpc->status) {
 344                 const struct byteq *q = &rpc->input;
 345                 if (q->head <= q->size) {
 346                     stream_report_content(q->buffer, q->head, STREAM_JSONRPC,
 347                                           THIS_MODULE, rpc->name);
 348                 }
 349                 return rpc->status;
 350             }
 351         }
 352     }
 353
 354     return EAGAIN;
 355 }
 356
 357 /* Causes the poll loop to wake up when jsonrpc_recv() may return a value other
 358  * than EAGAIN. */
 359 void
 360 jsonrpc_recv_wait(struct jsonrpc *rpc)
 361 {
 362     if (rpc->status || !byteq_is_empty(&rpc->input)) {
 363         poll_immediate_wake_at(rpc->name);
 364     } else {
 365         stream_recv_wait(rpc->stream);
 366     }
 367 }
 368
 369 /* Sends 'msg' on 'rpc' and waits for it to be successfully queued to the
 370  * underlying stream.  Returns 0 if 'msg' was sent successfully, otherwise a
 371  * status value (see jsonrpc_get_status()).
 372  *
 373  * Always takes ownership of 'msg', regardless of success. */
 374 int
 375 jsonrpc_send_block(struct jsonrpc *rpc, struct jsonrpc_msg *msg)
 376 {
 377     int error;
 378
 379     fatal_signal_run();
 380
 381     error = jsonrpc_send(rpc, msg);
 382     if (error) {
 383         return error;
 384     }
 385
 386     for (;;) {
 387         jsonrpc_run(rpc);
 388         if (list_is_empty(&rpc->output) || rpc->status) {
 389             return rpc->status;
 390         }
 391         jsonrpc_wait(rpc);
 392         poll_block();
 393     }
 394 }
 395
 396 /* Waits for a message to be received on 'rpc'.  Same semantics as
 397  * jsonrpc_recv() except that EAGAIN will never be returned. */
 398 int
 399 jsonrpc_recv_block(struct jsonrpc *rpc, struct jsonrpc_msg **msgp)
 400 {
 401     for (;;) {
 402         int error = jsonrpc_recv(rpc, msgp);
 403         if (error != EAGAIN) {
 404             fatal_signal_run();
 405             return error;
 406         }
 407
 408         jsonrpc_run(rpc);
 409         jsonrpc_wait(rpc);
 410         jsonrpc_recv_wait(rpc);
 411         poll_block();
 412     }
 413 }
 414
 415 /* Sends 'request' to 'rpc' then waits for a reply.  The return value is 0 if
 416  * successful, in which case '*replyp' is set to the reply, which the caller
 417  * must eventually free with jsonrpc_msg_destroy().  Otherwise returns a status
 418  * value (see jsonrpc_get_status()).
 419  *
 420  * Discards any message received on 'rpc' that is not a reply to 'request'
 421  * (based on message id).
 422  *
 423  * Always takes ownership of 'request', regardless of success. */
 424 int
 425 jsonrpc_transact_block(struct jsonrpc *rpc, struct jsonrpc_msg *request,
 426                        struct jsonrpc_msg **replyp)
 427 {
 428     struct jsonrpc_msg *reply = NULL;
 429     struct json *id;
 430     int error;
 431
 432     id = json_clone(request->id);
 433     error = jsonrpc_send_block(rpc, request);
 434     if (!error) {
 435         for (;;) {
 436             error = jsonrpc_recv_block(rpc, &reply);
 437             if (error) {
 438                 break;
 439             }
 440             if ((reply->type == JSONRPC_REPLY || reply->type == JSONRPC_ERROR)
 441                 && json_equal(id, reply->id)) {
 442                 break;
 443             }
 444             jsonrpc_msg_destroy(reply);
 445         }
 446     }
 447     *replyp = error ? NULL : reply;
 448     json_destroy(id);
 449     return error;
 450 }
 451
 452 /* Attempts to parse the content of 'rpc->parser' (which is complete JSON) as a
 453  * JSON-RPC message.  If successful, returns the JSON-RPC message.  On failure,
 454  * signals an error on 'rpc' with jsonrpc_error() and returns NULL. */
 455 static struct jsonrpc_msg *
 456 jsonrpc_parse_received_message(struct jsonrpc *rpc)
 457 {
 458     struct jsonrpc_msg *msg;
 459     struct json *json;
 460     char *error;
 461
 462     json = json_parser_finish(rpc->parser);
 463     rpc->parser = NULL;
 464     if (json->type == JSON_STRING) {
 465         VLOG_WARN_RL(&rl, "%s: error parsing stream: %s",
 466                      rpc->name, json_string(json));
 467         jsonrpc_error(rpc, EPROTO);
 468         json_destroy(json);
 469         return NULL;
 470     }
 471
 472     error = jsonrpc_msg_from_json(json, &msg);
 473     if (error) {
 474         VLOG_WARN_RL(&rl, "%s: received bad JSON-RPC message: %s",
 475                      rpc->name, error);
 476         free(error);
 477         jsonrpc_error(rpc, EPROTO);
 478         return NULL;
 479     }
 480
 481     jsonrpc_log_msg(rpc, "received", msg);
 482     return msg;
 483 }
 484
 485 static void
 486 jsonrpc_error(struct jsonrpc *rpc, int error)
 487 {
 488     ovs_assert(error);
 489     if (!rpc->status) {
 490         rpc->status = error;
 491         jsonrpc_cleanup(rpc);
 492     }
 493 }
 494
 495 static void
 496 jsonrpc_cleanup(struct jsonrpc *rpc)
 497 {
 498     stream_close(rpc->stream);
 499     rpc->stream = NULL;
 500
 501     json_parser_abort(rpc->parser);
 502     rpc->parser = NULL;
 503
 504     ofpbuf_list_delete(&rpc->output);
 505     rpc->backlog = 0;
 506     rpc->output_count = 0;
 507 }
 508 \f
 509 static struct jsonrpc_msg *
 510 jsonrpc_create(enum jsonrpc_msg_type type, const char *method,
 511                 struct json *params, struct json *result, struct json *error,
 512                 struct json *id)
 513 {
 514     struct jsonrpc_msg *msg = xmalloc(sizeof *msg);
 515     msg->type = type;
 516     msg->method = method ? xstrdup(method) : NULL;
 517     msg->params = params;
 518     msg->result = result;
 519     msg->error = error;
 520     msg->id = id;
 521     return msg;
 522 }
 523
 524 static struct json *
 525 jsonrpc_create_id(void)
 526 {
 527     static atomic_count next_id = ATOMIC_COUNT_INIT(0);
 528     unsigned int id;
 529
 530     id = atomic_count_inc(&next_id);
 531     return json_integer_create(id);
 532 }
 533
 534 struct jsonrpc_msg *
 535 jsonrpc_create_request(const char *method, struct json *params,
 536                        struct json **idp)
 537 {
 538     struct json *id = jsonrpc_create_id();
 539     if (idp) {
 540         *idp = json_clone(id);
 541     }
 542     return jsonrpc_create(JSONRPC_REQUEST, method, params, NULL, NULL, id);
 543 }
 544
 545 struct jsonrpc_msg *
 546 jsonrpc_create_notify(const char *method, struct json *params)
 547 {
 548     return jsonrpc_create(JSONRPC_NOTIFY, method, params, NULL, NULL, NULL);
 549 }
 550
 551 struct jsonrpc_msg *
 552 jsonrpc_create_reply(struct json *result, const struct json *id)
 553 {
 554     return jsonrpc_create(JSONRPC_REPLY, NULL, NULL, result, NULL,
 555                            json_clone(id));
 556 }
 557
 558 struct jsonrpc_msg *
 559 jsonrpc_create_error(struct json *error, const struct json *id)
 560 {
 561     return jsonrpc_create(JSONRPC_REPLY, NULL, NULL, NULL, error,
 562                            json_clone(id));
 563 }
 564
 565 const char *
 566 jsonrpc_msg_type_to_string(enum jsonrpc_msg_type type)
 567 {
 568     switch (type) {
 569     case JSONRPC_REQUEST:
 570         return "request";
 571
 572     case JSONRPC_NOTIFY:
 573         return "notification";
 574
 575     case JSONRPC_REPLY:
 576         return "reply";
 577
 578     case JSONRPC_ERROR:
 579         return "error";
 580     }
 581     return "(null)";
 582 }
 583
 584 char *
 585 jsonrpc_msg_is_valid(const struct jsonrpc_msg *m)
 586 {
 587     const char *type_name;
 588     unsigned int pattern;
 589
 590     if (m->params && m->params->type != JSON_ARRAY) {
 591         return xstrdup("\"params\" must be JSON array");
 592     }
 593
 594     switch (m->type) {
 595     case JSONRPC_REQUEST:
 596         pattern = 0x11001;
 597         break;
 598
 599     case JSONRPC_NOTIFY:
 600         pattern = 0x11000;
 601         break;
 602
 603     case JSONRPC_REPLY:
 604         pattern = 0x00101;
 605         break;
 606
 607     case JSONRPC_ERROR:
 608         pattern = 0x00011;
 609         break;
 610
 611     default:
 612         return xasprintf("invalid JSON-RPC message type %d", m->type);
 613     }
 614
 615     type_name = jsonrpc_msg_type_to_string(m->type);
 616     if ((m->method != NULL) != ((pattern & 0x10000) != 0)) {
 617         return xasprintf("%s must%s have \"method\"",
 618                          type_name, (pattern & 0x10000) ? "" : " not");
 619
 620     }
 621     if ((m->params != NULL) != ((pattern & 0x1000) != 0)) {
 622         return xasprintf("%s must%s have \"params\"",
 623                          type_name, (pattern & 0x1000) ? "" : " not");
 624
 625     }
 626     if ((m->result != NULL) != ((pattern & 0x100) != 0)) {
 627         return xasprintf("%s must%s have \"result\"",
 628                          type_name, (pattern & 0x100) ? "" : " not");
 629
 630     }
 631     if ((m->error != NULL) != ((pattern & 0x10) != 0)) {
 632         return xasprintf("%s must%s have \"error\"",
 633                          type_name, (pattern & 0x10) ? "" : " not");
 634
 635     }
 636     if ((m->id != NULL) != ((pattern & 0x1) != 0)) {
 637         return xasprintf("%s must%s have \"id\"",
 638                          type_name, (pattern & 0x1) ? "" : " not");
 639
 640     }
 641     return NULL;
 642 }
 643
 644 void
 645 jsonrpc_msg_destroy(struct jsonrpc_msg *m)
 646 {
 647     if (m) {
 648         free(m->method);
 649         json_destroy(m->params);
 650         json_destroy(m->result);
 651         json_destroy(m->error);
 652         json_destroy(m->id);
 653         free(m);
 654     }
 655 }
 656
 657 static struct json *
 658 null_from_json_null(struct json *json)
 659 {
 660     if (json && json->type == JSON_NULL) {
 661         json_destroy(json);
 662         return NULL;
 663     }
 664     return json;
 665 }
 666
 667 char *
 668 jsonrpc_msg_from_json(struct json *json, struct jsonrpc_msg **msgp)
 669 {
 670     struct json *method = NULL;
 671     struct jsonrpc_msg *msg = NULL;
 672     struct shash *object;
 673     char *error;
 674
 675     if (json->type != JSON_OBJECT) {
 676         error = xstrdup("message is not a JSON object");
 677         goto exit;
 678     }
 679     object = json_object(json);
 680
 681     method = shash_find_and_delete(object, "method");
 682     if (method && method->type != JSON_STRING) {
 683         error = xstrdup("method is not a JSON string");
 684         goto exit;
 685     }
 686
 687     msg = xzalloc(sizeof *msg);
 688     msg->method = method ? xstrdup(method->u.string) : NULL;
 689     msg->params = null_from_json_null(shash_find_and_delete(object, "params"));
 690     msg->result = null_from_json_null(shash_find_and_delete(object, "result"));
 691     msg->error = null_from_json_null(shash_find_and_delete(object, "error"));
 692     msg->id = null_from_json_null(shash_find_and_delete(object, "id"));
 693     msg->type = (msg->result ? JSONRPC_REPLY
 694                  : msg->error ? JSONRPC_ERROR
 695                  : msg->id ? JSONRPC_REQUEST
 696                  : JSONRPC_NOTIFY);
 697     if (!shash_is_empty(object)) {
 698         error = xasprintf("message has unexpected member \"%s\"",
 699                           shash_first(object)->name);
 700         goto exit;
 701     }
 702     error = jsonrpc_msg_is_valid(msg);
 703     if (error) {
 704         goto exit;
 705     }
 706
 707 exit:
 708     json_destroy(method);
 709     json_destroy(json);
 710     if (error) {
 711         jsonrpc_msg_destroy(msg);
 712         msg = NULL;
 713     }
 714     *msgp = msg;
 715     return error;
 716 }
 717
 718 struct json *
 719 jsonrpc_msg_to_json(struct jsonrpc_msg *m)
 720 {
 721     struct json *json = json_object_create();
 722
 723     if (m->method) {
 724         json_object_put(json, "method", json_string_create_nocopy(m->method));
 725     }
 726
 727     if (m->params) {
 728         json_object_put(json, "params", m->params);
 729     }
 730
 731     if (m->result) {
 732         json_object_put(json, "result", m->result);
 733     } else if (m->type == JSONRPC_ERROR) {
 734         json_object_put(json, "result", json_null_create());
 735     }
 736
 737     if (m->error) {
 738         json_object_put(json, "error", m->error);
 739     } else if (m->type == JSONRPC_REPLY) {
 740         json_object_put(json, "error", json_null_create());
 741     }
 742
 743     if (m->id) {
 744         json_object_put(json, "id", m->id);
 745     } else if (m->type == JSONRPC_NOTIFY) {
 746         json_object_put(json, "id", json_null_create());
 747     }
 748
 749     free(m);
 750
 751     return json;
 752 }
 753 \f
 754 /* A JSON-RPC session with reconnection. */
 755
 756 struct jsonrpc_session {
 757     struct reconnect *reconnect;
 758     struct jsonrpc *rpc;
 759     struct stream *stream;
 760     struct pstream *pstream;
 761     int last_error;
 762     unsigned int seqno;
 763     uint8_t dscp;
 764 };
 765
 766 /* Creates and returns a jsonrpc_session to 'name', which should be a string
 767  * acceptable to stream_open() or pstream_open().
 768  *
 769  * If 'name' is an active connection method, e.g. "tcp:127.1.2.3", the new
 770  * jsonrpc_session connects to 'name'.  If 'retry' is true, then the new
 771  * session connects and reconnects to 'name', with backoff.  If 'retry' is
 772  * false, the new session will only try to connect once and after a connection
 773  * failure or a disconnection jsonrpc_session_is_alive() will return false for
 774  * the new session.
 775  *
 776  * If 'name' is a passive connection method, e.g. "ptcp:", the new
 777  * jsonrpc_session listens for connections to 'name'.  It maintains at most one
 778  * connection at any given time.  Any new connection causes the previous one
 779  * (if any) to be dropped. */
 780 struct jsonrpc_session *
 781 jsonrpc_session_open(const char *name, bool retry)
 782 {
 783     struct jsonrpc_session *s;
 784
 785     s = xmalloc(sizeof *s);
 786     s->reconnect = reconnect_create(time_msec());
 787     reconnect_set_name(s->reconnect, name);
 788     reconnect_enable(s->reconnect, time_msec());
 789     s->rpc = NULL;
 790     s->stream = NULL;
 791     s->pstream = NULL;
 792     s->seqno = 0;
 793     s->dscp = 0;
 794     s->last_error = 0;
 795
 796     if (!pstream_verify_name(name)) {
 797         reconnect_set_passive(s->reconnect, true, time_msec());
 798     } else if (!retry) {
 799         reconnect_set_max_tries(s->reconnect, 1);
 800         reconnect_set_backoff(s->reconnect, INT_MAX, INT_MAX);
 801     }
 802
 803     if (!stream_or_pstream_needs_probes(name)) {
 804         reconnect_set_probe_interval(s->reconnect, 0);
 805     }
 806
 807     return s;
 808 }
 809
 810 /* Creates and returns a jsonrpc_session that is initially connected to
 811  * 'jsonrpc'.  If the connection is dropped, it will not be reconnected.
 812  *
 813  * On the assumption that such connections are likely to be short-lived
 814  * (e.g. from ovs-vsctl), informational logging for them is suppressed. */
 815 struct jsonrpc_session *
 816 jsonrpc_session_open_unreliably(struct jsonrpc *jsonrpc, uint8_t dscp)
 817 {
 818     struct jsonrpc_session *s;
 819
 820     s = xmalloc(sizeof *s);
 821     s->reconnect = reconnect_create(time_msec());
 822     reconnect_set_quiet(s->reconnect, true);
 823     reconnect_set_name(s->reconnect, jsonrpc_get_name(jsonrpc));
 824     reconnect_set_max_tries(s->reconnect, 0);
 825     reconnect_connected(s->reconnect, time_msec());
 826     s->dscp = dscp;
 827     s->rpc = jsonrpc;
 828     s->stream = NULL;
 829     s->pstream = NULL;
 830     s->seqno = 0;
 831
 832     return s;
 833 }
 834
 835 void
 836 jsonrpc_session_close(struct jsonrpc_session *s)
 837 {
 838     if (s) {
 839         jsonrpc_close(s->rpc);
 840         reconnect_destroy(s->reconnect);
 841         stream_close(s->stream);
 842         pstream_close(s->pstream);
 843         free(s);
 844     }
 845 }
 846
 847 static void
 848 jsonrpc_session_disconnect(struct jsonrpc_session *s)
 849 {
 850     if (s->rpc) {
 851         jsonrpc_error(s->rpc, EOF);
 852         jsonrpc_close(s->rpc);
 853         s->rpc = NULL;
 854         s->seqno++;
 855     } else if (s->stream) {
 856         stream_close(s->stream);
 857         s->stream = NULL;
 858         s->seqno++;
 859     }
 860 }
 861
 862 static void
 863 jsonrpc_session_connect(struct jsonrpc_session *s)
 864 {
 865     const char *name = reconnect_get_name(s->reconnect);
 866     int error;
 867
 868     jsonrpc_session_disconnect(s);
 869     if (!reconnect_is_passive(s->reconnect)) {
 870         error = jsonrpc_stream_open(name, &s->stream, s->dscp);
 871         if (!error) {
 872             reconnect_connecting(s->reconnect, time_msec());
 873         } else {
 874             s->last_error = error;
 875         }
 876     } else {
 877         error = s->pstream ? 0 : jsonrpc_pstream_open(name, &s->pstream,
 878                                                       s->dscp);
 879         if (!error) {
 880             reconnect_listening(s->reconnect, time_msec());
 881         }
 882     }
 883
 884     if (error) {
 885         reconnect_connect_failed(s->reconnect, time_msec(), error);
 886     }
 887     s->seqno++;
 888 }
 889
 890 void
 891 jsonrpc_session_run(struct jsonrpc_session *s)
 892 {
 893     if (s->pstream) {
 894         struct stream *stream;
 895         int error;
 896
 897         error = pstream_accept(s->pstream, &stream);
 898         if (!error) {
 899             if (s->rpc || s->stream) {
 900                 VLOG_INFO_RL(&rl,
 901                              "%s: new connection replacing active connection",
 902                              reconnect_get_name(s->reconnect));
 903                 jsonrpc_session_disconnect(s);
 904             }
 905             reconnect_connected(s->reconnect, time_msec());
 906             s->rpc = jsonrpc_open(stream);
 907         } else if (error != EAGAIN) {
 908             reconnect_listen_error(s->reconnect, time_msec(), error);
 909             pstream_close(s->pstream);
 910             s->pstream = NULL;
 911         }
 912     }
 913
 914     if (s->rpc) {
 915         size_t backlog;
 916         int error;
 917
 918         backlog = jsonrpc_get_backlog(s->rpc);
 919         jsonrpc_run(s->rpc);
 920         if (jsonrpc_get_backlog(s->rpc) < backlog) {
 921             /* Data previously caught in a queue was successfully sent (or
 922              * there's an error, which we'll catch below.)
 923              *
 924              * We don't count data that is successfully sent immediately as
 925              * activity, because there's a lot of queuing downstream from us,
 926              * which means that we can push a lot of data into a connection
 927              * that has stalled and won't ever recover.
 928              */
 929             reconnect_activity(s->reconnect, time_msec());
 930         }
 931
 932         error = jsonrpc_get_status(s->rpc);
 933         if (error) {
 934             reconnect_disconnected(s->reconnect, time_msec(), error);
 935             jsonrpc_session_disconnect(s);
 936             s->last_error = error;
 937         }
 938     } else if (s->stream) {
 939         int error;
 940
 941         stream_run(s->stream);
 942         error = stream_connect(s->stream);
 943         if (!error) {
 944             reconnect_connected(s->reconnect, time_msec());
 945             s->rpc = jsonrpc_open(s->stream);
 946             s->stream = NULL;
 947         } else if (error != EAGAIN) {
 948             reconnect_connect_failed(s->reconnect, time_msec(), error);
 949             stream_close(s->stream);
 950             s->stream = NULL;
 951         }
 952     }
 953
 954     switch (reconnect_run(s->reconnect, time_msec())) {
 955     case RECONNECT_CONNECT:
 956         jsonrpc_session_connect(s);
 957         break;
 958
 959     case RECONNECT_DISCONNECT:
 960         reconnect_disconnected(s->reconnect, time_msec(), 0);
 961         jsonrpc_session_disconnect(s);
 962         break;
 963
 964     case RECONNECT_PROBE:
 965         if (s->rpc) {
 966             struct json *params;
 967             struct jsonrpc_msg *request;
 968
 969             params = json_array_create_empty();
 970             request = jsonrpc_create_request("echo", params, NULL);
 971             json_destroy(request->id);
 972             request->id = json_string_create("echo");
 973             jsonrpc_send(s->rpc, request);
 974         }
 975         break;
 976     }
 977 }
 978
 979 void
 980 jsonrpc_session_wait(struct jsonrpc_session *s)
 981 {
 982     if (s->rpc) {
 983         jsonrpc_wait(s->rpc);
 984     } else if (s->stream) {
 985         stream_run_wait(s->stream);
 986         stream_connect_wait(s->stream);
 987     }
 988     if (s->pstream) {
 989         pstream_wait(s->pstream);
 990     }
 991     reconnect_wait(s->reconnect, time_msec());
 992 }
 993
 994 size_t
 995 jsonrpc_session_get_backlog(const struct jsonrpc_session *s)
 996 {
 997     return s->rpc ? jsonrpc_get_backlog(s->rpc) : 0;
 998 }
 999
1000 /* Always returns a pointer to a valid C string, assuming 's' was initialized
1001  * correctly. */
1002 const char *
1003 jsonrpc_session_get_name(const struct jsonrpc_session *s)
1004 {
1005     return reconnect_get_name(s->reconnect);
1006 }
1007
1008 /* Always takes ownership of 'msg', regardless of success. */
1009 int
1010 jsonrpc_session_send(struct jsonrpc_session *s, struct jsonrpc_msg *msg)
1011 {
1012     if (s->rpc) {
1013         return jsonrpc_send(s->rpc, msg);
1014     } else {
1015         jsonrpc_msg_destroy(msg);
1016         return ENOTCONN;
1017     }
1018 }
1019
1020 struct jsonrpc_msg *
1021 jsonrpc_session_recv(struct jsonrpc_session *s)
1022 {
1023     if (s->rpc) {
1024         unsigned int received_bytes;
1025         struct jsonrpc_msg *msg;
1026
1027         received_bytes = jsonrpc_get_received_bytes(s->rpc);
1028         jsonrpc_recv(s->rpc, &msg);
1029         if (received_bytes != jsonrpc_get_received_bytes(s->rpc)) {
1030             /* Data was successfully received.
1031              *
1032              * Previously we only counted receiving a full message as activity,
1033              * but with large messages or a slow connection that policy could
1034              * time out the session mid-message. */
1035             reconnect_activity(s->reconnect, time_msec());
1036         }
1037
1038         if (msg) {
1039             if (msg->type == JSONRPC_REQUEST && !strcmp(msg->method, "echo")) {
1040                 /* Echo request.  Send reply. */
1041                 struct jsonrpc_msg *reply;
1042
1043                 reply = jsonrpc_create_reply(json_clone(msg->params), msg->id);
1044                 jsonrpc_session_send(s, reply);
1045             } else if (msg->type == JSONRPC_REPLY
1046                        && msg->id && msg->id->type == JSON_STRING
1047                        && !strcmp(msg->id->u.string, "echo")) {
1048                 /* It's a reply to our echo request.  Suppress it. */
1049             } else {
1050                 return msg;
1051             }
1052             jsonrpc_msg_destroy(msg);
1053         }
1054     }
1055     return NULL;
1056 }
1057
1058 void
1059 jsonrpc_session_recv_wait(struct jsonrpc_session *s)
1060 {
1061     if (s->rpc) {
1062         jsonrpc_recv_wait(s->rpc);
1063     }
1064 }
1065
1066 /* Returns true if 's' is currently connected or trying to connect. */
1067 bool
1068 jsonrpc_session_is_alive(const struct jsonrpc_session *s)
1069 {
1070     return s->rpc || s->stream || reconnect_get_max_tries(s->reconnect);
1071 }
1072
1073 /* Returns true if 's' is currently connected. */
1074 bool
1075 jsonrpc_session_is_connected(const struct jsonrpc_session *s)
1076 {
1077     return s->rpc != NULL;
1078 }
1079
1080 /* Returns a sequence number for 's'.  The sequence number increments every
1081  * time 's' connects or disconnects.  Thus, a caller can use the change (or
1082  * lack of change) in the sequence number to figure out whether the underlying
1083  * connection is the same as before. */
1084 unsigned int
1085 jsonrpc_session_get_seqno(const struct jsonrpc_session *s)
1086 {
1087     return s->seqno;
1088 }
1089
1090 /* Returns the current status of 's'.  If 's' is NULL or is disconnected, this
1091  * is 0, otherwise it is the status of the connection, as reported by
1092  * jsonrpc_get_status(). */
1093 int
1094 jsonrpc_session_get_status(const struct jsonrpc_session *s)
1095 {
1096     return s && s->rpc ? jsonrpc_get_status(s->rpc) : 0;
1097 }
1098
1099 /* Returns the last error reported on a connection by 's'.  The return value is
1100  * 0 only if no connection made by 's' has ever encountered an error.  See
1101  * jsonrpc_get_status() for return value interpretation. */
1102 int
1103 jsonrpc_session_get_last_error(const struct jsonrpc_session *s)
1104 {
1105     return s->last_error;
1106 }
1107
1108 /* Populates 'stats' with statistics from 's'. */
1109 void
1110 jsonrpc_session_get_reconnect_stats(const struct jsonrpc_session *s,
1111                                     struct reconnect_stats *stats)
1112 {
1113     reconnect_get_stats(s->reconnect, time_msec(), stats);
1114 }
1115
1116 /* Enables 's' to reconnect to the peer if the connection drops. */
1117 void
1118 jsonrpc_session_enable_reconnect(struct jsonrpc_session *s)
1119 {
1120     reconnect_set_max_tries(s->reconnect, UINT_MAX);
1121     reconnect_set_backoff(s->reconnect, RECONNECT_DEFAULT_MIN_BACKOFF,
1122                           RECONNECT_DEFAULT_MAX_BACKOFF);
1123 }
1124
1125 /* Forces 's' to drop its connection (if any) and reconnect. */
1126 void
1127 jsonrpc_session_force_reconnect(struct jsonrpc_session *s)
1128 {
1129     reconnect_force_reconnect(s->reconnect, time_msec());
1130 }
1131
1132 /* Sets 'max_backoff' as the maximum time, in milliseconds, to wait after a
1133  * connection attempt fails before attempting to connect again. */
1134 void
1135 jsonrpc_session_set_max_backoff(struct jsonrpc_session *s, int max_backoff)
1136 {
1137     reconnect_set_backoff(s->reconnect, 0, max_backoff);
1138 }
1139
1140 /* Sets the "probe interval" for 's' to 'probe_interval', in milliseconds.  If
1141  * this is zero, it disables the connection keepalive feature.  Otherwise, if
1142  * 's' is idle for 'probe_interval' milliseconds then 's' will send an echo
1143  * request and, if no reply is received within an additional 'probe_interval'
1144  * milliseconds, close the connection (then reconnect, if that feature is
1145  * enabled). */
1146 void
1147 jsonrpc_session_set_probe_interval(struct jsonrpc_session *s,
1148                                    int probe_interval)
1149 {
1150     reconnect_set_probe_interval(s->reconnect, probe_interval);
1151 }
1152
1153 /* Sets the DSCP value used for 's''s connection to 'dscp'.  If this is
1154  * different from the DSCP value currently in use then the connection is closed
1155  * and reconnected. */
1156 void
1157 jsonrpc_session_set_dscp(struct jsonrpc_session *s, uint8_t dscp)
1158 {
1159     if (s->dscp != dscp) {
1160         pstream_close(s->pstream);
1161         s->pstream = NULL;
1162
1163         s->dscp = dscp;
1164         jsonrpc_session_force_reconnect(s);
1165     }
1166 }