lib/jsonrpc.c

   1 /*
   2  * Copyright (c) 2009, 2010, 2011, 2012 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 "poll-loop.h"
  30 #include "reconnect.h"
  31 #include "stream.h"
  32 #include "timeval.h"
  33 #include "vlog.h"
  34
  35 VLOG_DEFINE_THIS_MODULE(jsonrpc);
  36 \f
  37 struct jsonrpc {
  38     struct stream *stream;
  39     char *name;
  40     int status;
  41
  42     /* Input. */
  43     struct byteq input;
  44     struct json_parser *parser;
  45     struct jsonrpc_msg *received;
  46
  47     /* Output. */
  48     struct list output;         /* Contains "struct ofpbuf"s. */
  49     size_t backlog;
  50 };
  51
  52 /* Rate limit for error messages. */
  53 static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 5);
  54
  55 static void jsonrpc_received(struct jsonrpc *);
  56 static void jsonrpc_cleanup(struct jsonrpc *);
  57 static void jsonrpc_error(struct jsonrpc *, int error);
  58
  59 /* This is just the same as stream_open() except that it uses the default
  60  * JSONRPC ports if none is specified. */
  61 int
  62 jsonrpc_stream_open(const char *name, struct stream **streamp, uint8_t dscp)
  63 {
  64     return stream_open_with_default_ports(name, JSONRPC_TCP_PORT,
  65                                           JSONRPC_SSL_PORT, streamp,
  66                                           dscp);
  67 }
  68
  69 /* This is just the same as pstream_open() except that it uses the default
  70  * JSONRPC ports 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_ports(name, JSONRPC_TCP_PORT,
  75                                            JSONRPC_SSL_PORT, pstreamp, dscp);
  76 }
  77
  78 /* Returns a new JSON-RPC stream that uses 'stream' for input and output.  The
  79  * new jsonrpc object takes ownership of 'stream'. */
  80 struct jsonrpc *
  81 jsonrpc_open(struct stream *stream)
  82 {
  83     struct jsonrpc *rpc;
  84
  85     ovs_assert(stream != NULL);
  86
  87     rpc = xzalloc(sizeof *rpc);
  88     rpc->name = xstrdup(stream_get_name(stream));
  89     rpc->stream = stream;
  90     byteq_init(&rpc->input);
  91     list_init(&rpc->output);
  92
  93     return rpc;
  94 }
  95
  96 /* Destroys 'rpc', closing the stream on which it is based, and frees its
  97  * memory. */
  98 void
  99 jsonrpc_close(struct jsonrpc *rpc)
 100 {
 101     if (rpc) {
 102         jsonrpc_cleanup(rpc);
 103         free(rpc->name);
 104         free(rpc);
 105     }
 106 }
 107
 108 /* Performs periodic maintenance on 'rpc', such as flushing output buffers. */
 109 void
 110 jsonrpc_run(struct jsonrpc *rpc)
 111 {
 112     if (rpc->status) {
 113         return;
 114     }
 115
 116     stream_run(rpc->stream);
 117     while (!list_is_empty(&rpc->output)) {
 118         struct ofpbuf *buf = ofpbuf_from_list(rpc->output.next);
 119         int retval;
 120
 121         retval = stream_send(rpc->stream, buf->data, buf->size);
 122         if (retval >= 0) {
 123             rpc->backlog -= retval;
 124             ofpbuf_pull(buf, retval);
 125             if (!buf->size) {
 126                 list_remove(&buf->list_node);
 127                 ofpbuf_delete(buf);
 128             }
 129         } else {
 130             if (retval != -EAGAIN) {
 131                 VLOG_WARN_RL(&rl, "%s: send error: %s",
 132                              rpc->name, 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->backlog += length;
 261
 262     if (rpc->backlog == length) {
 263         jsonrpc_run(rpc);
 264     }
 265     return rpc->status;
 266 }
 267
 268 /* Attempts to receive a message from 'rpc'.
 269  *
 270  * If successful, stores the received message in '*msgp' and returns 0.  The
 271  * caller takes ownership of '*msgp' and must eventually destroy it with
 272  * jsonrpc_msg_destroy().
 273  *
 274  * Otherwise, stores NULL in '*msgp' and returns one of the following:
 275  *
 276  *   - EAGAIN: No message has been received.
 277  *
 278  *   - EOF: The remote end closed the connection gracefully.
 279  *
 280  *   - Otherwise an errno value that represents a JSON-RPC protocol violation
 281  *     or another error fatal to the connection.  'rpc' will not send or
 282  *     receive any more messages.
 283  */
 284 int
 285 jsonrpc_recv(struct jsonrpc *rpc, struct jsonrpc_msg **msgp)
 286 {
 287     int i;
 288
 289     *msgp = NULL;
 290     if (rpc->status) {
 291         return rpc->status;
 292     }
 293
 294     for (i = 0; i < 50; i++) {
 295         if (rpc->received) {
 296             *msgp = rpc->received;
 297             rpc->received = NULL;
 298             return 0;
 299         } else if (byteq_is_empty(&rpc->input)) {
 300             size_t chunk;
 301             int retval;
 302
 303             chunk = byteq_headroom(&rpc->input);
 304             retval = stream_recv(rpc->stream, byteq_head(&rpc->input), chunk);
 305             if (retval < 0) {
 306                 if (retval == -EAGAIN) {
 307                     return EAGAIN;
 308                 } else {
 309                     VLOG_WARN_RL(&rl, "%s: receive error: %s",
 310                                  rpc->name, strerror(-retval));
 311                     jsonrpc_error(rpc, -retval);
 312                     return rpc->status;
 313                 }
 314             } else if (retval == 0) {
 315                 jsonrpc_error(rpc, EOF);
 316                 return EOF;
 317             }
 318             byteq_advance_head(&rpc->input, retval);
 319         } else {
 320             size_t n, used;
 321
 322             if (!rpc->parser) {
 323                 rpc->parser = json_parser_create(0);
 324             }
 325             n = byteq_tailroom(&rpc->input);
 326             used = json_parser_feed(rpc->parser,
 327                                     (char *) byteq_tail(&rpc->input), n);
 328             byteq_advance_tail(&rpc->input, used);
 329             if (json_parser_is_done(rpc->parser)) {
 330                 jsonrpc_received(rpc);
 331                 if (rpc->status) {
 332                     const struct byteq *q = &rpc->input;
 333                     if (q->head <= BYTEQ_SIZE) {
 334                         stream_report_content(q->buffer, q->head,
 335                                               STREAM_JSONRPC,
 336                                               THIS_MODULE, rpc->name);
 337                     }
 338                     return rpc->status;
 339                 }
 340             }
 341         }
 342     }
 343
 344     return EAGAIN;
 345 }
 346
 347 /* Causes the poll loop to wake up when jsonrpc_recv() may return a value other
 348  * than EAGAIN. */
 349 void
 350 jsonrpc_recv_wait(struct jsonrpc *rpc)
 351 {
 352     if (rpc->status || rpc->received || !byteq_is_empty(&rpc->input)) {
 353         (poll_immediate_wake)(rpc->name);
 354     } else {
 355         stream_recv_wait(rpc->stream);
 356     }
 357 }
 358
 359 /* Sends 'msg' on 'rpc' and waits for it to be successfully queued to the
 360  * underlying stream.  Returns 0 if 'msg' was sent successfully, otherwise a
 361  * status value (see jsonrpc_get_status()).
 362  *
 363  * Always takes ownership of 'msg', regardless of success. */
 364 int
 365 jsonrpc_send_block(struct jsonrpc *rpc, struct jsonrpc_msg *msg)
 366 {
 367     int error;
 368
 369     fatal_signal_run();
 370
 371     error = jsonrpc_send(rpc, msg);
 372     if (error) {
 373         return error;
 374     }
 375
 376     for (;;) {
 377         jsonrpc_run(rpc);
 378         if (list_is_empty(&rpc->output) || rpc->status) {
 379             return rpc->status;
 380         }
 381         jsonrpc_wait(rpc);
 382         poll_block();
 383     }
 384 }
 385
 386 /* Waits for a message to be received on 'rpc'.  Same semantics as
 387  * jsonrpc_recv() except that EAGAIN will never be returned. */
 388 int
 389 jsonrpc_recv_block(struct jsonrpc *rpc, struct jsonrpc_msg **msgp)
 390 {
 391     for (;;) {
 392         int error = jsonrpc_recv(rpc, msgp);
 393         if (error != EAGAIN) {
 394             fatal_signal_run();
 395             return error;
 396         }
 397
 398         jsonrpc_run(rpc);
 399         jsonrpc_wait(rpc);
 400         jsonrpc_recv_wait(rpc);
 401         poll_block();
 402     }
 403 }
 404
 405 /* Sends 'request' to 'rpc' then waits for a reply.  The return value is 0 if
 406  * successful, in which case '*replyp' is set to the reply, which the caller
 407  * must eventually free with jsonrpc_msg_destroy().  Otherwise returns a status
 408  * value (see jsonrpc_get_status()).
 409  *
 410  * Discards any message received on 'rpc' that is not a reply to 'request'
 411  * (based on message id).
 412  *
 413  * Always takes ownership of 'request', regardless of success. */
 414 int
 415 jsonrpc_transact_block(struct jsonrpc *rpc, struct jsonrpc_msg *request,
 416                        struct jsonrpc_msg **replyp)
 417 {
 418     struct jsonrpc_msg *reply = NULL;
 419     struct json *id;
 420     int error;
 421
 422     id = json_clone(request->id);
 423     error = jsonrpc_send_block(rpc, request);
 424     if (!error) {
 425         for (;;) {
 426             error = jsonrpc_recv_block(rpc, &reply);
 427             if (error) {
 428                 break;
 429             }
 430             if ((reply->type == JSONRPC_REPLY || reply->type == JSONRPC_ERROR)
 431                 && json_equal(id, reply->id)) {
 432                 break;
 433             }
 434             jsonrpc_msg_destroy(reply);
 435         }
 436     }
 437     *replyp = error ? NULL : reply;
 438     json_destroy(id);
 439     return error;
 440 }
 441
 442 static void
 443 jsonrpc_received(struct jsonrpc *rpc)
 444 {
 445     struct jsonrpc_msg *msg;
 446     struct json *json;
 447     char *error;
 448
 449     json = json_parser_finish(rpc->parser);
 450     rpc->parser = NULL;
 451     if (json->type == JSON_STRING) {
 452         VLOG_WARN_RL(&rl, "%s: error parsing stream: %s",
 453                      rpc->name, json_string(json));
 454         jsonrpc_error(rpc, EPROTO);
 455         json_destroy(json);
 456         return;
 457     }
 458
 459     error = jsonrpc_msg_from_json(json, &msg);
 460     if (error) {
 461         VLOG_WARN_RL(&rl, "%s: received bad JSON-RPC message: %s",
 462                      rpc->name, error);
 463         free(error);
 464         jsonrpc_error(rpc, EPROTO);
 465         return;
 466     }
 467
 468     jsonrpc_log_msg(rpc, "received", msg);
 469     rpc->received = msg;
 470 }
 471
 472 static void
 473 jsonrpc_error(struct jsonrpc *rpc, int error)
 474 {
 475     ovs_assert(error);
 476     if (!rpc->status) {
 477         rpc->status = error;
 478         jsonrpc_cleanup(rpc);
 479     }
 480 }
 481
 482 static void
 483 jsonrpc_cleanup(struct jsonrpc *rpc)
 484 {
 485     stream_close(rpc->stream);
 486     rpc->stream = NULL;
 487
 488     json_parser_abort(rpc->parser);
 489     rpc->parser = NULL;
 490
 491     jsonrpc_msg_destroy(rpc->received);
 492     rpc->received = NULL;
 493
 494     ofpbuf_list_delete(&rpc->output);
 495     rpc->backlog = 0;
 496 }
 497 \f
 498 static struct jsonrpc_msg *
 499 jsonrpc_create(enum jsonrpc_msg_type type, const char *method,
 500                 struct json *params, struct json *result, struct json *error,
 501                 struct json *id)
 502 {
 503     struct jsonrpc_msg *msg = xmalloc(sizeof *msg);
 504     msg->type = type;
 505     msg->method = method ? xstrdup(method) : NULL;
 506     msg->params = params;
 507     msg->result = result;
 508     msg->error = error;
 509     msg->id = id;
 510     return msg;
 511 }
 512
 513 static struct json *
 514 jsonrpc_create_id(void)
 515 {
 516     static unsigned int id;
 517     return json_integer_create(id++);
 518 }
 519
 520 struct jsonrpc_msg *
 521 jsonrpc_create_request(const char *method, struct json *params,
 522                        struct json **idp)
 523 {
 524     struct json *id = jsonrpc_create_id();
 525     if (idp) {
 526         *idp = json_clone(id);
 527     }
 528     return jsonrpc_create(JSONRPC_REQUEST, method, params, NULL, NULL, id);
 529 }
 530
 531 struct jsonrpc_msg *
 532 jsonrpc_create_notify(const char *method, struct json *params)
 533 {
 534     return jsonrpc_create(JSONRPC_NOTIFY, method, params, NULL, NULL, NULL);
 535 }
 536
 537 struct jsonrpc_msg *
 538 jsonrpc_create_reply(struct json *result, const struct json *id)
 539 {
 540     return jsonrpc_create(JSONRPC_REPLY, NULL, NULL, result, NULL,
 541                            json_clone(id));
 542 }
 543
 544 struct jsonrpc_msg *
 545 jsonrpc_create_error(struct json *error, const struct json *id)
 546 {
 547     return jsonrpc_create(JSONRPC_REPLY, NULL, NULL, NULL, error,
 548                            json_clone(id));
 549 }
 550
 551 const char *
 552 jsonrpc_msg_type_to_string(enum jsonrpc_msg_type type)
 553 {
 554     switch (type) {
 555     case JSONRPC_REQUEST:
 556         return "request";
 557
 558     case JSONRPC_NOTIFY:
 559         return "notification";
 560
 561     case JSONRPC_REPLY:
 562         return "reply";
 563
 564     case JSONRPC_ERROR:
 565         return "error";
 566     }
 567     return "(null)";
 568 }
 569
 570 char *
 571 jsonrpc_msg_is_valid(const struct jsonrpc_msg *m)
 572 {
 573     const char *type_name;
 574     unsigned int pattern;
 575
 576     if (m->params && m->params->type != JSON_ARRAY) {
 577         return xstrdup("\"params\" must be JSON array");
 578     }
 579
 580     switch (m->type) {
 581     case JSONRPC_REQUEST:
 582         pattern = 0x11001;
 583         break;
 584
 585     case JSONRPC_NOTIFY:
 586         pattern = 0x11000;
 587         break;
 588
 589     case JSONRPC_REPLY:
 590         pattern = 0x00101;
 591         break;
 592
 593     case JSONRPC_ERROR:
 594         pattern = 0x00011;
 595         break;
 596
 597     default:
 598         return xasprintf("invalid JSON-RPC message type %d", m->type);
 599     }
 600
 601     type_name = jsonrpc_msg_type_to_string(m->type);
 602     if ((m->method != NULL) != ((pattern & 0x10000) != 0)) {
 603         return xasprintf("%s must%s have \"method\"",
 604                          type_name, (pattern & 0x10000) ? "" : " not");
 605
 606     }
 607     if ((m->params != NULL) != ((pattern & 0x1000) != 0)) {
 608         return xasprintf("%s must%s have \"params\"",
 609                          type_name, (pattern & 0x1000) ? "" : " not");
 610
 611     }
 612     if ((m->result != NULL) != ((pattern & 0x100) != 0)) {
 613         return xasprintf("%s must%s have \"result\"",
 614                          type_name, (pattern & 0x100) ? "" : " not");
 615
 616     }
 617     if ((m->error != NULL) != ((pattern & 0x10) != 0)) {
 618         return xasprintf("%s must%s have \"error\"",
 619                          type_name, (pattern & 0x10) ? "" : " not");
 620
 621     }
 622     if ((m->id != NULL) != ((pattern & 0x1) != 0)) {
 623         return xasprintf("%s must%s have \"id\"",
 624                          type_name, (pattern & 0x1) ? "" : " not");
 625
 626     }
 627     return NULL;
 628 }
 629
 630 void
 631 jsonrpc_msg_destroy(struct jsonrpc_msg *m)
 632 {
 633     if (m) {
 634         free(m->method);
 635         json_destroy(m->params);
 636         json_destroy(m->result);
 637         json_destroy(m->error);
 638         json_destroy(m->id);
 639         free(m);
 640     }
 641 }
 642
 643 static struct json *
 644 null_from_json_null(struct json *json)
 645 {
 646     if (json && json->type == JSON_NULL) {
 647         json_destroy(json);
 648         return NULL;
 649     }
 650     return json;
 651 }
 652
 653 char *
 654 jsonrpc_msg_from_json(struct json *json, struct jsonrpc_msg **msgp)
 655 {
 656     struct json *method = NULL;
 657     struct jsonrpc_msg *msg = NULL;
 658     struct shash *object;
 659     char *error;
 660
 661     if (json->type != JSON_OBJECT) {
 662         error = xstrdup("message is not a JSON object");
 663         goto exit;
 664     }
 665     object = json_object(json);
 666
 667     method = shash_find_and_delete(object, "method");
 668     if (method && method->type != JSON_STRING) {
 669         error = xstrdup("method is not a JSON string");
 670         goto exit;
 671     }
 672
 673     msg = xzalloc(sizeof *msg);
 674     msg->method = method ? xstrdup(method->u.string) : NULL;
 675     msg->params = null_from_json_null(shash_find_and_delete(object, "params"));
 676     msg->result = null_from_json_null(shash_find_and_delete(object, "result"));
 677     msg->error = null_from_json_null(shash_find_and_delete(object, "error"));
 678     msg->id = null_from_json_null(shash_find_and_delete(object, "id"));
 679     msg->type = (msg->result ? JSONRPC_REPLY
 680                  : msg->error ? JSONRPC_ERROR
 681                  : msg->id ? JSONRPC_REQUEST
 682                  : JSONRPC_NOTIFY);
 683     if (!shash_is_empty(object)) {
 684         error = xasprintf("message has unexpected member \"%s\"",
 685                           shash_first(object)->name);
 686         goto exit;
 687     }
 688     error = jsonrpc_msg_is_valid(msg);
 689     if (error) {
 690         goto exit;
 691     }
 692
 693 exit:
 694     json_destroy(method);
 695     json_destroy(json);
 696     if (error) {
 697         jsonrpc_msg_destroy(msg);
 698         msg = NULL;
 699     }
 700     *msgp = msg;
 701     return error;
 702 }
 703
 704 struct json *
 705 jsonrpc_msg_to_json(struct jsonrpc_msg *m)
 706 {
 707     struct json *json = json_object_create();
 708
 709     if (m->method) {
 710         json_object_put(json, "method", json_string_create_nocopy(m->method));
 711     }
 712
 713     if (m->params) {
 714         json_object_put(json, "params", m->params);
 715     }
 716
 717     if (m->result) {
 718         json_object_put(json, "result", m->result);
 719     } else if (m->type == JSONRPC_ERROR) {
 720         json_object_put(json, "result", json_null_create());
 721     }
 722
 723     if (m->error) {
 724         json_object_put(json, "error", m->error);
 725     } else if (m->type == JSONRPC_REPLY) {
 726         json_object_put(json, "error", json_null_create());
 727     }
 728
 729     if (m->id) {
 730         json_object_put(json, "id", m->id);
 731     } else if (m->type == JSONRPC_NOTIFY) {
 732         json_object_put(json, "id", json_null_create());
 733     }
 734
 735     free(m);
 736
 737     return json;
 738 }
 739 \f
 740 /* A JSON-RPC session with reconnection. */
 741
 742 struct jsonrpc_session {
 743     struct reconnect *reconnect;
 744     struct jsonrpc *rpc;
 745     struct stream *stream;
 746     struct pstream *pstream;
 747     unsigned int seqno;
 748     uint8_t dscp;
 749 };
 750
 751 /* Creates and returns a jsonrpc_session to 'name', which should be a string
 752  * acceptable to stream_open() or pstream_open().
 753  *
 754  * If 'name' is an active connection method, e.g. "tcp:127.1.2.3", the new
 755  * jsonrpc_session connects and reconnects, with back-off, to 'name'.
 756  *
 757  * If 'name' is a passive connection method, e.g. "ptcp:", the new
 758  * jsonrpc_session listens for connections to 'name'.  It maintains at most one
 759  * connection at any given time.  Any new connection causes the previous one
 760  * (if any) to be dropped. */
 761 struct jsonrpc_session *
 762 jsonrpc_session_open(const char *name)
 763 {
 764     struct jsonrpc_session *s;
 765
 766     s = xmalloc(sizeof *s);
 767     s->reconnect = reconnect_create(time_msec());
 768     reconnect_set_name(s->reconnect, name);
 769     reconnect_enable(s->reconnect, time_msec());
 770     s->rpc = NULL;
 771     s->stream = NULL;
 772     s->pstream = NULL;
 773     s->seqno = 0;
 774     s->dscp = 0;
 775
 776     if (!pstream_verify_name(name)) {
 777         reconnect_set_passive(s->reconnect, true, time_msec());
 778     }
 779
 780     if (!stream_or_pstream_needs_probes(name)) {
 781         reconnect_set_probe_interval(s->reconnect, 0);
 782     }
 783
 784     return s;
 785 }
 786
 787 /* Creates and returns a jsonrpc_session that is initially connected to
 788  * 'jsonrpc'.  If the connection is dropped, it will not be reconnected.
 789  *
 790  * On the assumption that such connections are likely to be short-lived
 791  * (e.g. from ovs-vsctl), informational logging for them is suppressed. */
 792 struct jsonrpc_session *
 793 jsonrpc_session_open_unreliably(struct jsonrpc *jsonrpc, uint8_t dscp)
 794 {
 795     struct jsonrpc_session *s;
 796
 797     s = xmalloc(sizeof *s);
 798     s->reconnect = reconnect_create(time_msec());
 799     reconnect_set_quiet(s->reconnect, true);
 800     reconnect_set_name(s->reconnect, jsonrpc_get_name(jsonrpc));
 801     reconnect_set_max_tries(s->reconnect, 0);
 802     reconnect_connected(s->reconnect, time_msec());
 803     s->dscp = dscp;
 804     s->rpc = jsonrpc;
 805     s->stream = NULL;
 806     s->pstream = NULL;
 807     s->seqno = 0;
 808
 809     return s;
 810 }
 811
 812 void
 813 jsonrpc_session_close(struct jsonrpc_session *s)
 814 {
 815     if (s) {
 816         jsonrpc_close(s->rpc);
 817         reconnect_destroy(s->reconnect);
 818         stream_close(s->stream);
 819         pstream_close(s->pstream);
 820         free(s);
 821     }
 822 }
 823
 824 static void
 825 jsonrpc_session_disconnect(struct jsonrpc_session *s)
 826 {
 827     if (s->rpc) {
 828         jsonrpc_error(s->rpc, EOF);
 829         jsonrpc_close(s->rpc);
 830         s->rpc = NULL;
 831         s->seqno++;
 832     } else if (s->stream) {
 833         stream_close(s->stream);
 834         s->stream = NULL;
 835         s->seqno++;
 836     }
 837 }
 838
 839 static void
 840 jsonrpc_session_connect(struct jsonrpc_session *s)
 841 {
 842     const char *name = reconnect_get_name(s->reconnect);
 843     int error;
 844
 845     jsonrpc_session_disconnect(s);
 846     if (!reconnect_is_passive(s->reconnect)) {
 847         error = jsonrpc_stream_open(name, &s->stream, s->dscp);
 848         if (!error) {
 849             reconnect_connecting(s->reconnect, time_msec());
 850         }
 851     } else {
 852         error = s->pstream ? 0 : jsonrpc_pstream_open(name, &s->pstream,
 853                                                       s->dscp);
 854         if (!error) {
 855             reconnect_listening(s->reconnect, time_msec());
 856         }
 857     }
 858
 859     if (error) {
 860         reconnect_connect_failed(s->reconnect, time_msec(), error);
 861     }
 862     s->seqno++;
 863 }
 864
 865 void
 866 jsonrpc_session_run(struct jsonrpc_session *s)
 867 {
 868     if (s->pstream) {
 869         struct stream *stream;
 870         int error;
 871
 872         error = pstream_accept(s->pstream, &stream);
 873         if (!error) {
 874             if (s->rpc || s->stream) {
 875                 VLOG_INFO_RL(&rl,
 876                              "%s: new connection replacing active connection",
 877                              reconnect_get_name(s->reconnect));
 878                 jsonrpc_session_disconnect(s);
 879             }
 880             reconnect_connected(s->reconnect, time_msec());
 881             s->rpc = jsonrpc_open(stream);
 882         } else if (error != EAGAIN) {
 883             reconnect_listen_error(s->reconnect, time_msec(), error);
 884             pstream_close(s->pstream);
 885             s->pstream = NULL;
 886         }
 887     }
 888
 889     if (s->rpc) {
 890         size_t backlog;
 891         int error;
 892
 893         backlog = jsonrpc_get_backlog(s->rpc);
 894         jsonrpc_run(s->rpc);
 895         if (jsonrpc_get_backlog(s->rpc) < backlog) {
 896             /* Data previously caught in a queue was successfully sent (or
 897              * there's an error, which we'll catch below.)
 898              *
 899              * We don't count data that is successfully sent immediately as
 900              * activity, because there's a lot of queuing downstream from us,
 901              * which means that we can push a lot of data into a connection
 902              * that has stalled and won't ever recover.
 903              */
 904             reconnect_activity(s->reconnect, time_msec());
 905         }
 906
 907         error = jsonrpc_get_status(s->rpc);
 908         if (error) {
 909             reconnect_disconnected(s->reconnect, time_msec(), error);
 910             jsonrpc_session_disconnect(s);
 911         }
 912     } else if (s->stream) {
 913         int error;
 914
 915         stream_run(s->stream);
 916         error = stream_connect(s->stream);
 917         if (!error) {
 918             reconnect_connected(s->reconnect, time_msec());
 919             s->rpc = jsonrpc_open(s->stream);
 920             s->stream = NULL;
 921         } else if (error != EAGAIN) {
 922             reconnect_connect_failed(s->reconnect, time_msec(), error);
 923             stream_close(s->stream);
 924             s->stream = NULL;
 925         }
 926     }
 927
 928     switch (reconnect_run(s->reconnect, time_msec())) {
 929     case RECONNECT_CONNECT:
 930         jsonrpc_session_connect(s);
 931         break;
 932
 933     case RECONNECT_DISCONNECT:
 934         reconnect_disconnected(s->reconnect, time_msec(), 0);
 935         jsonrpc_session_disconnect(s);
 936         break;
 937
 938     case RECONNECT_PROBE:
 939         if (s->rpc) {
 940             struct json *params;
 941             struct jsonrpc_msg *request;
 942
 943             params = json_array_create_empty();
 944             request = jsonrpc_create_request("echo", params, NULL);
 945             json_destroy(request->id);
 946             request->id = json_string_create("echo");
 947             jsonrpc_send(s->rpc, request);
 948         }
 949         break;
 950     }
 951 }
 952
 953 void
 954 jsonrpc_session_wait(struct jsonrpc_session *s)
 955 {
 956     if (s->rpc) {
 957         jsonrpc_wait(s->rpc);
 958     } else if (s->stream) {
 959         stream_run_wait(s->stream);
 960         stream_connect_wait(s->stream);
 961     }
 962     if (s->pstream) {
 963         pstream_wait(s->pstream);
 964     }
 965     reconnect_wait(s->reconnect, time_msec());
 966 }
 967
 968 size_t
 969 jsonrpc_session_get_backlog(const struct jsonrpc_session *s)
 970 {
 971     return s->rpc ? jsonrpc_get_backlog(s->rpc) : 0;
 972 }
 973
 974 /* Always returns a pointer to a valid C string, assuming 's' was initialized
 975  * correctly. */
 976 const char *
 977 jsonrpc_session_get_name(const struct jsonrpc_session *s)
 978 {
 979     return reconnect_get_name(s->reconnect);
 980 }
 981
 982 /* Always takes ownership of 'msg', regardless of success. */
 983 int
 984 jsonrpc_session_send(struct jsonrpc_session *s, struct jsonrpc_msg *msg)
 985 {
 986     if (s->rpc) {
 987         return jsonrpc_send(s->rpc, msg);
 988     } else {
 989         jsonrpc_msg_destroy(msg);
 990         return ENOTCONN;
 991     }
 992 }
 993
 994 struct jsonrpc_msg *
 995 jsonrpc_session_recv(struct jsonrpc_session *s)
 996 {
 997     if (s->rpc) {
 998         unsigned int received_bytes;
 999         struct jsonrpc_msg *msg;
1000
1001         received_bytes = jsonrpc_get_received_bytes(s->rpc);
1002         jsonrpc_recv(s->rpc, &msg);
1003         if (received_bytes != jsonrpc_get_received_bytes(s->rpc)) {
1004             /* Data was successfully received.
1005              *
1006              * Previously we only counted receiving a full message as activity,
1007              * but with large messages or a slow connection that policy could
1008              * time out the session mid-message. */
1009             reconnect_activity(s->reconnect, time_msec());
1010         }
1011
1012         if (msg) {
1013             if (msg->type == JSONRPC_REQUEST && !strcmp(msg->method, "echo")) {
1014                 /* Echo request.  Send reply. */
1015                 struct jsonrpc_msg *reply;
1016
1017                 reply = jsonrpc_create_reply(json_clone(msg->params), msg->id);
1018                 jsonrpc_session_send(s, reply);
1019             } else if (msg->type == JSONRPC_REPLY
1020                        && msg->id && msg->id->type == JSON_STRING
1021                        && !strcmp(msg->id->u.string, "echo")) {
1022                 /* It's a reply to our echo request.  Suppress it. */
1023             } else {
1024                 return msg;
1025             }
1026             jsonrpc_msg_destroy(msg);
1027         }
1028     }
1029     return NULL;
1030 }
1031
1032 void
1033 jsonrpc_session_recv_wait(struct jsonrpc_session *s)
1034 {
1035     if (s->rpc) {
1036         jsonrpc_recv_wait(s->rpc);
1037     }
1038 }
1039
1040 bool
1041 jsonrpc_session_is_alive(const struct jsonrpc_session *s)
1042 {
1043     return s->rpc || s->stream || reconnect_get_max_tries(s->reconnect);
1044 }
1045
1046 bool
1047 jsonrpc_session_is_connected(const struct jsonrpc_session *s)
1048 {
1049     return s->rpc != NULL;
1050 }
1051
1052 unsigned int
1053 jsonrpc_session_get_seqno(const struct jsonrpc_session *s)
1054 {
1055     return s->seqno;
1056 }
1057
1058 int
1059 jsonrpc_session_get_status(const struct jsonrpc_session *s)
1060 {
1061     return s && s->rpc ? jsonrpc_get_status(s->rpc) : 0;
1062 }
1063
1064 void
1065 jsonrpc_session_get_reconnect_stats(const struct jsonrpc_session *s,
1066                                     struct reconnect_stats *stats)
1067 {
1068     reconnect_get_stats(s->reconnect, time_msec(), stats);
1069 }
1070
1071 void
1072 jsonrpc_session_force_reconnect(struct jsonrpc_session *s)
1073 {
1074     reconnect_force_reconnect(s->reconnect, time_msec());
1075 }
1076
1077 void
1078 jsonrpc_session_set_max_backoff(struct jsonrpc_session *s, int max_backoff)
1079 {
1080     reconnect_set_backoff(s->reconnect, 0, max_backoff);
1081 }
1082
1083 void
1084 jsonrpc_session_set_probe_interval(struct jsonrpc_session *s,
1085                                    int probe_interval)
1086 {
1087     reconnect_set_probe_interval(s->reconnect, probe_interval);
1088 }
1089
1090 void
1091 jsonrpc_session_set_dscp(struct jsonrpc_session *s,
1092                          uint8_t dscp)
1093 {
1094     if (s->dscp != dscp) {
1095         if (s->pstream) {
1096             int error;
1097
1098             error = pstream_set_dscp(s->pstream, dscp);
1099             if (error) {
1100                 VLOG_ERR("%s: failed set_dscp %s",
1101                          reconnect_get_name(s->reconnect), strerror(error));
1102             }
1103             /*
1104              * XXX race window between setting dscp to listening socket
1105              * and accepting socket. accepted socket may have old dscp value.
1106              * Ignore this race window for now.
1107              */
1108         }
1109         s->dscp = dscp;
1110         jsonrpc_session_force_reconnect(s);
1111     }
1112 }