lib/jsonrpc.c

   1 /*
   2  * Copyright (c) 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016 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 "openvswitch/dynamic-string.h"
  25 #include "fatal-signal.h"
  26 #include "openvswitch/json.h"
  27 #include "openvswitch/list.h"
  28 #include "openvswitch/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     ovs_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 (!ovs_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                 ovs_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 (!ovs_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 function returns nonzero, 'rpc' is effectively out of
 160  * commission.  'rpc' will not receive any more messages and any further
 161  * messages that one attempts to send with 'rpc' will be discarded.  The
 162  * caller can keep 'rpc' around as long as it wants, but it's not going
 163  * to provide any more useful 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
 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     json_to_ds(json, 0, &ds);
 253     length = ds.length;
 254     json_destroy(json);
 255
 256     buf = xmalloc(sizeof *buf);
 257     ofpbuf_use_ds(buf, &ds);
 258     ovs_list_push_back(&rpc->output, &buf->list_node);
 259     rpc->output_count++;
 260     rpc->backlog += length;
 261
 262     if (rpc->output_count >= 50) {
 263         VLOG_INFO_RL(&rl, "excessive sending backlog, jsonrpc: %s, num of"
 264                      " msgs: %"PRIuSIZE", backlog: %"PRIuSIZE".", rpc->name,
 265                      rpc->output_count, rpc->backlog);
 266     }
 267
 268     if (rpc->backlog == length) {
 269         jsonrpc_run(rpc);
 270     }
 271     return rpc->status;
 272 }
 273
 274 /* Attempts to receive a message from 'rpc'.
 275  *
 276  * If successful, stores the received message in '*msgp' and returns 0.  The
 277  * caller takes ownership of '*msgp' and must eventually destroy it with
 278  * jsonrpc_msg_destroy().
 279  *
 280  * Otherwise, stores NULL in '*msgp' and returns one of the following:
 281  *
 282  *   - EAGAIN: No message has been received.
 283  *
 284  *   - EOF: The remote end closed the connection gracefully.
 285  *
 286  *   - Otherwise an errno value that represents a JSON-RPC protocol violation
 287  *     or another error fatal to the connection.  'rpc' will not send or
 288  *     receive any more messages.
 289  */
 290 int
 291 jsonrpc_recv(struct jsonrpc *rpc, struct jsonrpc_msg **msgp)
 292 {
 293     int i;
 294
 295     *msgp = NULL;
 296     if (rpc->status) {
 297         return rpc->status;
 298     }
 299
 300     for (i = 0; i < 50; i++) {
 301         size_t n, used;
 302
 303         /* Fill our input buffer if it's empty. */
 304         if (byteq_is_empty(&rpc->input)) {
 305             size_t chunk;
 306             int retval;
 307
 308             chunk = byteq_headroom(&rpc->input);
 309             retval = stream_recv(rpc->stream, byteq_head(&rpc->input), chunk);
 310             if (retval < 0) {
 311                 if (retval == -EAGAIN) {
 312                     return EAGAIN;
 313                 } else {
 314                     VLOG_WARN_RL(&rl, "%s: receive error: %s",
 315                                  rpc->name, ovs_strerror(-retval));
 316                     jsonrpc_error(rpc, -retval);
 317                     return rpc->status;
 318                 }
 319             } else if (retval == 0) {
 320                 jsonrpc_error(rpc, EOF);
 321                 return EOF;
 322             }
 323             byteq_advance_head(&rpc->input, retval);
 324         }
 325
 326         /* We have some input.  Feed it into the JSON parser. */
 327         if (!rpc->parser) {
 328             rpc->parser = json_parser_create(0);
 329         }
 330         n = byteq_tailroom(&rpc->input);
 331         used = json_parser_feed(rpc->parser,
 332                                 (char *) byteq_tail(&rpc->input), n);
 333         byteq_advance_tail(&rpc->input, used);
 334
 335         /* If we have complete JSON, attempt to parse it as JSON-RPC. */
 336         if (json_parser_is_done(rpc->parser)) {
 337             *msgp = jsonrpc_parse_received_message(rpc);
 338             if (*msgp) {
 339                 return 0;
 340             }
 341
 342             if (rpc->status) {
 343                 const struct byteq *q = &rpc->input;
 344                 if (q->head <= q->size) {
 345                     stream_report_content(q->buffer, q->head, STREAM_JSONRPC,
 346                                           &this_module, rpc->name);
 347                 }
 348                 return rpc->status;
 349             }
 350         }
 351     }
 352
 353     return EAGAIN;
 354 }
 355
 356 /* Causes the poll loop to wake up when jsonrpc_recv() may return a value other
 357  * than EAGAIN. */
 358 void
 359 jsonrpc_recv_wait(struct jsonrpc *rpc)
 360 {
 361     if (rpc->status || !byteq_is_empty(&rpc->input)) {
 362         poll_immediate_wake_at(rpc->name);
 363     } else {
 364         stream_recv_wait(rpc->stream);
 365     }
 366 }
 367
 368 /* Sends 'msg' on 'rpc' and waits for it to be successfully queued to the
 369  * underlying stream.  Returns 0 if 'msg' was sent successfully, otherwise a
 370  * status value (see jsonrpc_get_status()).
 371  *
 372  * Always takes ownership of 'msg', regardless of success. */
 373 int
 374 jsonrpc_send_block(struct jsonrpc *rpc, struct jsonrpc_msg *msg)
 375 {
 376     int error;
 377
 378     fatal_signal_run();
 379
 380     error = jsonrpc_send(rpc, msg);
 381     if (error) {
 382         return error;
 383     }
 384
 385     for (;;) {
 386         jsonrpc_run(rpc);
 387         if (ovs_list_is_empty(&rpc->output) || rpc->status) {
 388             return rpc->status;
 389         }
 390         jsonrpc_wait(rpc);
 391         poll_block();
 392     }
 393 }
 394
 395 /* Waits for a message to be received on 'rpc'.  Same semantics as
 396  * jsonrpc_recv() except that EAGAIN will never be returned. */
 397 int
 398 jsonrpc_recv_block(struct jsonrpc *rpc, struct jsonrpc_msg **msgp)
 399 {
 400     for (;;) {
 401         int error = jsonrpc_recv(rpc, msgp);
 402         if (error != EAGAIN) {
 403             fatal_signal_run();
 404             return error;
 405         }
 406
 407         jsonrpc_run(rpc);
 408         jsonrpc_wait(rpc);
 409         jsonrpc_recv_wait(rpc);
 410         poll_block();
 411     }
 412 }
 413
 414 /* Sends 'request' to 'rpc' then waits for a reply.  The return value is 0 if
 415  * successful, in which case '*replyp' is set to the reply, which the caller
 416  * must eventually free with jsonrpc_msg_destroy().  Otherwise returns a status
 417  * value (see jsonrpc_get_status()).
 418  *
 419  * Discards any message received on 'rpc' that is not a reply to 'request'
 420  * (based on message id).
 421  *
 422  * Always takes ownership of 'request', regardless of success. */
 423 int
 424 jsonrpc_transact_block(struct jsonrpc *rpc, struct jsonrpc_msg *request,
 425                        struct jsonrpc_msg **replyp)
 426 {
 427     struct jsonrpc_msg *reply = NULL;
 428     struct json *id;
 429     int error;
 430
 431     id = json_clone(request->id);
 432     error = jsonrpc_send_block(rpc, request);
 433     if (!error) {
 434         for (;;) {
 435             error = jsonrpc_recv_block(rpc, &reply);
 436             if (error) {
 437                 break;
 438             }
 439             if ((reply->type == JSONRPC_REPLY || reply->type == JSONRPC_ERROR)
 440                 && json_equal(id, reply->id)) {
 441                 break;
 442             }
 443             jsonrpc_msg_destroy(reply);
 444         }
 445     }
 446     *replyp = error ? NULL : reply;
 447     json_destroy(id);
 448     return error;
 449 }
 450
 451 /* Attempts to parse the content of 'rpc->parser' (which is complete JSON) as a
 452  * JSON-RPC message.  If successful, returns the JSON-RPC message.  On failure,
 453  * signals an error on 'rpc' with jsonrpc_error() and returns NULL. */
 454 static struct jsonrpc_msg *
 455 jsonrpc_parse_received_message(struct jsonrpc *rpc)
 456 {
 457     struct jsonrpc_msg *msg;
 458     struct json *json;
 459     char *error;
 460
 461     json = json_parser_finish(rpc->parser);
 462     rpc->parser = NULL;
 463     if (json->type == JSON_STRING) {
 464         VLOG_WARN_RL(&rl, "%s: error parsing stream: %s",
 465                      rpc->name, json_string(json));
 466         jsonrpc_error(rpc, EPROTO);
 467         json_destroy(json);
 468         return NULL;
 469     }
 470
 471     error = jsonrpc_msg_from_json(json, &msg);
 472     if (error) {
 473         VLOG_WARN_RL(&rl, "%s: received bad JSON-RPC message: %s",
 474                      rpc->name, error);
 475         free(error);
 476         jsonrpc_error(rpc, EPROTO);
 477         return NULL;
 478     }
 479
 480     jsonrpc_log_msg(rpc, "received", msg);
 481     return msg;
 482 }
 483
 484 static void
 485 jsonrpc_error(struct jsonrpc *rpc, int error)
 486 {
 487     ovs_assert(error);
 488     if (!rpc->status) {
 489         rpc->status = error;
 490         jsonrpc_cleanup(rpc);
 491     }
 492 }
 493
 494 static void
 495 jsonrpc_cleanup(struct jsonrpc *rpc)
 496 {
 497     stream_close(rpc->stream);
 498     rpc->stream = NULL;
 499
 500     json_parser_abort(rpc->parser);
 501     rpc->parser = NULL;
 502
 503     ofpbuf_list_delete(&rpc->output);
 504     rpc->backlog = 0;
 505     rpc->output_count = 0;
 506 }
 507 \f
 508 static struct jsonrpc_msg *
 509 jsonrpc_create(enum jsonrpc_msg_type type, const char *method,
 510                 struct json *params, struct json *result, struct json *error,
 511                 struct json *id)
 512 {
 513     struct jsonrpc_msg *msg = xmalloc(sizeof *msg);
 514     msg->type = type;
 515     msg->method = nullable_xstrdup(method);
 516     msg->params = params;
 517     msg->result = result;
 518     msg->error = error;
 519     msg->id = id;
 520     return msg;
 521 }
 522
 523 static struct json *
 524 jsonrpc_create_id(void)
 525 {
 526     static atomic_count next_id = ATOMIC_COUNT_INIT(0);
 527     unsigned int id;
 528
 529     id = atomic_count_inc(&next_id);
 530     return json_integer_create(id);
 531 }
 532
 533 struct jsonrpc_msg *
 534 jsonrpc_create_request(const char *method, struct json *params,
 535                        struct json **idp)
 536 {
 537     struct json *id = jsonrpc_create_id();
 538     if (idp) {
 539         *idp = json_clone(id);
 540     }
 541     return jsonrpc_create(JSONRPC_REQUEST, method, params, NULL, NULL, id);
 542 }
 543
 544 struct jsonrpc_msg *
 545 jsonrpc_create_notify(const char *method, struct json *params)
 546 {
 547     return jsonrpc_create(JSONRPC_NOTIFY, method, params, NULL, NULL, NULL);
 548 }
 549
 550 struct jsonrpc_msg *
 551 jsonrpc_create_reply(struct json *result, const struct json *id)
 552 {
 553     return jsonrpc_create(JSONRPC_REPLY, NULL, NULL, result, NULL,
 554                            json_clone(id));
 555 }
 556
 557 struct jsonrpc_msg *
 558 jsonrpc_create_error(struct json *error, const struct json *id)
 559 {
 560     return jsonrpc_create(JSONRPC_REPLY, NULL, NULL, NULL, error,
 561                            json_clone(id));
 562 }
 563
 564 const char *
 565 jsonrpc_msg_type_to_string(enum jsonrpc_msg_type type)
 566 {
 567     switch (type) {
 568     case JSONRPC_REQUEST:
 569         return "request";
 570
 571     case JSONRPC_NOTIFY:
 572         return "notification";
 573
 574     case JSONRPC_REPLY:
 575         return "reply";
 576
 577     case JSONRPC_ERROR:
 578         return "error";
 579     }
 580     return "(null)";
 581 }
 582
 583 char *
 584 jsonrpc_msg_is_valid(const struct jsonrpc_msg *m)
 585 {
 586     const char *type_name;
 587     unsigned int pattern;
 588
 589     if (m->params && m->params->type != JSON_ARRAY) {
 590         return xstrdup("\"params\" must be JSON array");
 591     }
 592
 593     switch (m->type) {
 594     case JSONRPC_REQUEST:
 595         pattern = 0x11001;
 596         break;
 597
 598     case JSONRPC_NOTIFY:
 599         pattern = 0x11000;
 600         break;
 601
 602     case JSONRPC_REPLY:
 603         pattern = 0x00101;
 604         break;
 605
 606     case JSONRPC_ERROR:
 607         pattern = 0x00011;
 608         break;
 609
 610     default:
 611         return xasprintf("invalid JSON-RPC message type %d", m->type);
 612     }
 613
 614     type_name = jsonrpc_msg_type_to_string(m->type);
 615     if ((m->method != NULL) != ((pattern & 0x10000) != 0)) {
 616         return xasprintf("%s must%s have \"method\"",
 617                          type_name, (pattern & 0x10000) ? "" : " not");
 618
 619     }
 620     if ((m->params != NULL) != ((pattern & 0x1000) != 0)) {
 621         return xasprintf("%s must%s have \"params\"",
 622                          type_name, (pattern & 0x1000) ? "" : " not");
 623
 624     }
 625     if ((m->result != NULL) != ((pattern & 0x100) != 0)) {
 626         return xasprintf("%s must%s have \"result\"",
 627                          type_name, (pattern & 0x100) ? "" : " not");
 628
 629     }
 630     if ((m->error != NULL) != ((pattern & 0x10) != 0)) {
 631         return xasprintf("%s must%s have \"error\"",
 632                          type_name, (pattern & 0x10) ? "" : " not");
 633
 634     }
 635     if ((m->id != NULL) != ((pattern & 0x1) != 0)) {
 636         return xasprintf("%s must%s have \"id\"",
 637                          type_name, (pattern & 0x1) ? "" : " not");
 638
 639     }
 640     return NULL;
 641 }
 642
 643 void
 644 jsonrpc_msg_destroy(struct jsonrpc_msg *m)
 645 {
 646     if (m) {
 647         free(m->method);
 648         json_destroy(m->params);
 649         json_destroy(m->result);
 650         json_destroy(m->error);
 651         json_destroy(m->id);
 652         free(m);
 653     }
 654 }
 655
 656 static struct json *
 657 null_from_json_null(struct json *json)
 658 {
 659     if (json && json->type == JSON_NULL) {
 660         json_destroy(json);
 661         return NULL;
 662     }
 663     return json;
 664 }
 665
 666 char *
 667 jsonrpc_msg_from_json(struct json *json, struct jsonrpc_msg **msgp)
 668 {
 669     struct json *method = NULL;
 670     struct jsonrpc_msg *msg = NULL;
 671     struct shash *object;
 672     char *error;
 673
 674     if (json->type != JSON_OBJECT) {
 675         error = xstrdup("message is not a JSON object");
 676         goto exit;
 677     }
 678     object = json_object(json);
 679
 680     method = shash_find_and_delete(object, "method");
 681     if (method && method->type != JSON_STRING) {
 682         error = xstrdup("method is not a JSON string");
 683         goto exit;
 684     }
 685
 686     msg = xzalloc(sizeof *msg);
 687     msg->method = method ? xstrdup(method->u.string) : NULL;
 688     msg->params = null_from_json_null(shash_find_and_delete(object, "params"));
 689     msg->result = null_from_json_null(shash_find_and_delete(object, "result"));
 690     msg->error = null_from_json_null(shash_find_and_delete(object, "error"));
 691     msg->id = null_from_json_null(shash_find_and_delete(object, "id"));
 692     msg->type = (msg->result ? JSONRPC_REPLY
 693                  : msg->error ? JSONRPC_ERROR
 694                  : msg->id ? JSONRPC_REQUEST
 695                  : JSONRPC_NOTIFY);
 696     if (!shash_is_empty(object)) {
 697         error = xasprintf("message has unexpected member \"%s\"",
 698                           shash_first(object)->name);
 699         goto exit;
 700     }
 701     error = jsonrpc_msg_is_valid(msg);
 702     if (error) {
 703         goto exit;
 704     }
 705
 706 exit:
 707     json_destroy(method);
 708     json_destroy(json);
 709     if (error) {
 710         jsonrpc_msg_destroy(msg);
 711         msg = NULL;
 712     }
 713     *msgp = msg;
 714     return error;
 715 }
 716
 717 struct json *
 718 jsonrpc_msg_to_json(struct jsonrpc_msg *m)
 719 {
 720     struct json *json = json_object_create();
 721
 722     if (m->method) {
 723         json_object_put(json, "method", json_string_create_nocopy(m->method));
 724     }
 725
 726     if (m->params) {
 727         json_object_put(json, "params", m->params);
 728     }
 729
 730     if (m->result) {
 731         json_object_put(json, "result", m->result);
 732     } else if (m->type == JSONRPC_ERROR) {
 733         json_object_put(json, "result", json_null_create());
 734     }
 735
 736     if (m->error) {
 737         json_object_put(json, "error", m->error);
 738     } else if (m->type == JSONRPC_REPLY) {
 739         json_object_put(json, "error", json_null_create());
 740     }
 741
 742     if (m->id) {
 743         json_object_put(json, "id", m->id);
 744     } else if (m->type == JSONRPC_NOTIFY) {
 745         json_object_put(json, "id", json_null_create());
 746     }
 747
 748     free(m);
 749
 750     return json;
 751 }
 752 \f
 753 /* A JSON-RPC session with reconnection. */
 754
 755 struct jsonrpc_session {
 756     struct reconnect *reconnect;
 757     struct jsonrpc *rpc;
 758     struct stream *stream;
 759     struct pstream *pstream;
 760     int last_error;
 761     unsigned int seqno;
 762     uint8_t dscp;
 763 };
 764
 765 /* Creates and returns a jsonrpc_session to 'name', which should be a string
 766  * acceptable to stream_open() or pstream_open().
 767  *
 768  * If 'name' is an active connection method, e.g. "tcp:127.1.2.3", the new
 769  * jsonrpc_session connects to 'name'.  If 'retry' is true, then the new
 770  * session connects and reconnects to 'name', with backoff.  If 'retry' is
 771  * false, the new session will only try to connect once and after a connection
 772  * failure or a disconnection jsonrpc_session_is_alive() will return false for
 773  * the new session.
 774  *
 775  * If 'name' is a passive connection method, e.g. "ptcp:", the new
 776  * jsonrpc_session listens for connections to 'name'.  It maintains at most one
 777  * connection at any given time.  Any new connection causes the previous one
 778  * (if any) to be dropped. */
 779 struct jsonrpc_session *
 780 jsonrpc_session_open(const char *name, bool retry)
 781 {
 782     struct jsonrpc_session *s;
 783
 784     s = xmalloc(sizeof *s);
 785     s->reconnect = reconnect_create(time_msec());
 786     reconnect_set_name(s->reconnect, name);
 787     reconnect_enable(s->reconnect, time_msec());
 788     s->rpc = NULL;
 789     s->stream = NULL;
 790     s->pstream = NULL;
 791     s->seqno = 0;
 792     s->dscp = 0;
 793     s->last_error = 0;
 794
 795     if (!pstream_verify_name(name)) {
 796         reconnect_set_passive(s->reconnect, true, time_msec());
 797     } else if (!retry) {
 798         reconnect_set_max_tries(s->reconnect, 1);
 799         reconnect_set_backoff(s->reconnect, INT_MAX, INT_MAX);
 800     }
 801
 802     if (!stream_or_pstream_needs_probes(name)) {
 803         reconnect_set_probe_interval(s->reconnect, 0);
 804     }
 805
 806     return s;
 807 }
 808
 809 /* Creates and returns a jsonrpc_session that is initially connected to
 810  * 'jsonrpc'.  If the connection is dropped, it will not be reconnected.
 811  *
 812  * On the assumption that such connections are likely to be short-lived
 813  * (e.g. from ovs-vsctl), informational logging for them is suppressed. */
 814 struct jsonrpc_session *
 815 jsonrpc_session_open_unreliably(struct jsonrpc *jsonrpc, uint8_t dscp)
 816 {
 817     struct jsonrpc_session *s;
 818
 819     s = xmalloc(sizeof *s);
 820     s->reconnect = reconnect_create(time_msec());
 821     reconnect_set_quiet(s->reconnect, true);
 822     reconnect_set_name(s->reconnect, jsonrpc_get_name(jsonrpc));
 823     reconnect_set_max_tries(s->reconnect, 0);
 824     reconnect_connected(s->reconnect, time_msec());
 825     s->dscp = dscp;
 826     s->rpc = jsonrpc;
 827     s->stream = NULL;
 828     s->pstream = NULL;
 829     s->seqno = 0;
 830
 831     return s;
 832 }
 833
 834 void
 835 jsonrpc_session_close(struct jsonrpc_session *s)
 836 {
 837     if (s) {
 838         jsonrpc_close(s->rpc);
 839         reconnect_destroy(s->reconnect);
 840         stream_close(s->stream);
 841         pstream_close(s->pstream);
 842         free(s);
 843     }
 844 }
 845
 846 static void
 847 jsonrpc_session_disconnect(struct jsonrpc_session *s)
 848 {
 849     if (s->rpc) {
 850         jsonrpc_error(s->rpc, EOF);
 851         jsonrpc_close(s->rpc);
 852         s->rpc = NULL;
 853         s->seqno++;
 854     } else if (s->stream) {
 855         stream_close(s->stream);
 856         s->stream = NULL;
 857         s->seqno++;
 858     }
 859 }
 860
 861 static void
 862 jsonrpc_session_connect(struct jsonrpc_session *s)
 863 {
 864     const char *name = reconnect_get_name(s->reconnect);
 865     int error;
 866
 867     jsonrpc_session_disconnect(s);
 868     if (!reconnect_is_passive(s->reconnect)) {
 869         error = jsonrpc_stream_open(name, &s->stream, s->dscp);
 870         if (!error) {
 871             reconnect_connecting(s->reconnect, time_msec());
 872         } else {
 873             s->last_error = error;
 874         }
 875     } else {
 876         error = s->pstream ? 0 : jsonrpc_pstream_open(name, &s->pstream,
 877                                                       s->dscp);
 878         if (!error) {
 879             reconnect_listening(s->reconnect, time_msec());
 880         }
 881     }
 882
 883     if (error) {
 884         reconnect_connect_failed(s->reconnect, time_msec(), error);
 885     }
 886     s->seqno++;
 887 }
 888
 889 void
 890 jsonrpc_session_run(struct jsonrpc_session *s)
 891 {
 892     if (s->pstream) {
 893         struct stream *stream;
 894         int error;
 895
 896         error = pstream_accept(s->pstream, &stream);
 897         if (!error) {
 898             if (s->rpc || s->stream) {
 899                 VLOG_INFO_RL(&rl,
 900                              "%s: new connection replacing active connection",
 901                              reconnect_get_name(s->reconnect));
 902                 jsonrpc_session_disconnect(s);
 903             }
 904             reconnect_connected(s->reconnect, time_msec());
 905             s->rpc = jsonrpc_open(stream);
 906         } else if (error != EAGAIN) {
 907             reconnect_listen_error(s->reconnect, time_msec(), error);
 908             pstream_close(s->pstream);
 909             s->pstream = NULL;
 910         }
 911     }
 912
 913     if (s->rpc) {
 914         size_t backlog;
 915         int error;
 916
 917         backlog = jsonrpc_get_backlog(s->rpc);
 918         jsonrpc_run(s->rpc);
 919         if (jsonrpc_get_backlog(s->rpc) < backlog) {
 920             /* Data previously caught in a queue was successfully sent (or
 921              * there's an error, which we'll catch below.)
 922              *
 923              * We don't count data that is successfully sent immediately as
 924              * activity, because there's a lot of queuing downstream from us,
 925              * which means that we can push a lot of data into a connection
 926              * that has stalled and won't ever recover.
 927              */
 928             reconnect_activity(s->reconnect, time_msec());
 929         }
 930
 931         error = jsonrpc_get_status(s->rpc);
 932         if (error) {
 933             reconnect_disconnected(s->reconnect, time_msec(), error);
 934             jsonrpc_session_disconnect(s);
 935             s->last_error = error;
 936         }
 937     } else if (s->stream) {
 938         int error;
 939
 940         stream_run(s->stream);
 941         error = stream_connect(s->stream);
 942         if (!error) {
 943             reconnect_connected(s->reconnect, time_msec());
 944             s->rpc = jsonrpc_open(s->stream);
 945             s->stream = NULL;
 946         } else if (error != EAGAIN) {
 947             reconnect_connect_failed(s->reconnect, time_msec(), error);
 948             stream_close(s->stream);
 949             s->stream = NULL;
 950             s->last_error = error;
 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 }