src/httpfetch.cpp

   1 /*
   2 Minetest
   3 Copyright (C) 2013 celeron55, Perttu Ahola <celeron55@gmail.com>
   4
   5 This program is free software; you can redistribute it and/or modify
   6 it under the terms of the GNU Lesser General Public License as published by
   7 the Free Software Foundation; either version 2.1 of the License, or
   8 (at your option) any later version.
   9
  10 This program is distributed in the hope that it will be useful,
  11 but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 GNU Lesser General Public License for more details.
  14
  15 You should have received a copy of the GNU Lesser General Public License along
  16 with this program; if not, write to the Free Software Foundation, Inc.,
  17 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  18 */
  19
  20 #include "httpfetch.h"
  21 #include <iostream>
  22 #include <sstream>
  23 #include <list>
  24 #include <map>
  25 #include <errno.h>
  26 #include "jthread/jevent.h"
  27 #include "config.h"
  28 #include "exceptions.h"
  29 #include "debug.h"
  30 #include "log.h"
  31 #include "util/container.h"
  32 #include "util/thread.h"
  33 #include "socket.h" // for select()
  34
  35 JMutex g_httpfetch_mutex;
  36 std::map<unsigned long, std::list<HTTPFetchResult> > g_httpfetch_results;
  37
  38 static void httpfetch_deliver_result(const HTTPFetchResult &fetchresult)
  39 {
  40         unsigned long caller = fetchresult.caller;
  41         if (caller != HTTPFETCH_DISCARD) {
  42                 JMutexAutoLock lock(g_httpfetch_mutex);
  43                 g_httpfetch_results[caller].push_back(fetchresult);
  44         }
  45 }
  46
  47 static void httpfetch_request_clear(unsigned long caller);
  48
  49 unsigned long httpfetch_caller_alloc()
  50 {
  51         JMutexAutoLock lock(g_httpfetch_mutex);
  52
  53         // Check each caller ID except HTTPFETCH_DISCARD
  54         const unsigned long discard = HTTPFETCH_DISCARD;
  55         for (unsigned long caller = discard + 1; caller != discard; ++caller) {
  56                 std::map<unsigned long, std::list<HTTPFetchResult> >::iterator
  57                         it = g_httpfetch_results.find(caller);
  58                 if (it == g_httpfetch_results.end()) {
  59                         verbosestream<<"httpfetch_caller_alloc: allocating "
  60                                         <<caller<<std::endl;
  61                         // Access element to create it
  62                         g_httpfetch_results[caller];
  63                         return caller;
  64                 }
  65         }
  66
  67         assert("httpfetch_caller_alloc: ran out of caller IDs" == 0);
  68         return discard;
  69 }
  70
  71 void httpfetch_caller_free(unsigned long caller)
  72 {
  73         verbosestream<<"httpfetch_caller_free: freeing "
  74                         <<caller<<std::endl;
  75
  76         httpfetch_request_clear(caller);
  77         if (caller != HTTPFETCH_DISCARD) {
  78                 JMutexAutoLock lock(g_httpfetch_mutex);
  79                 g_httpfetch_results.erase(caller);
  80         }
  81 }
  82
  83 bool httpfetch_async_get(unsigned long caller, HTTPFetchResult &fetchresult)
  84 {
  85         JMutexAutoLock lock(g_httpfetch_mutex);
  86
  87         // Check that caller exists
  88         std::map<unsigned long, std::list<HTTPFetchResult> >::iterator
  89                 it = g_httpfetch_results.find(caller);
  90         if (it == g_httpfetch_results.end())
  91                 return false;
  92
  93         // Check that result queue is nonempty
  94         std::list<HTTPFetchResult> &callerresults = it->second;
  95         if (callerresults.empty())
  96                 return false;
  97
  98         // Pop first result
  99         fetchresult = callerresults.front();
 100         callerresults.pop_front();
 101         return true;
 102 }
 103
 104 #if USE_CURL
 105 #include <curl/curl.h>
 106
 107 /*
 108         USE_CURL is on: use cURL based httpfetch implementation
 109 */
 110
 111 static size_t httpfetch_writefunction(
 112                 char *ptr, size_t size, size_t nmemb, void *userdata)
 113 {
 114         std::ostringstream *stream = (std::ostringstream*)userdata;
 115         size_t count = size * nmemb;
 116         stream->write(ptr, count);
 117         return count;
 118 }
 119
 120 static size_t httpfetch_discardfunction(
 121                 char *ptr, size_t size, size_t nmemb, void *userdata)
 122 {
 123         return size * nmemb;
 124 }
 125
 126 class CurlHandlePool
 127 {
 128         std::list<CURL*> handles;
 129
 130 public:
 131         CurlHandlePool() {}
 132         ~CurlHandlePool()
 133         {
 134                 for (std::list<CURL*>::iterator it = handles.begin();
 135                                 it != handles.end(); ++it) {
 136                         curl_easy_cleanup(*it);
 137                 }
 138         }
 139         CURL * alloc()
 140         {
 141                 CURL *curl;
 142                 if (handles.empty()) {
 143                         curl = curl_easy_init();
 144                         if (curl == NULL) {
 145                                 errorstream<<"curl_easy_init returned NULL"<<std::endl;
 146                         }
 147                 }
 148                 else {
 149                         curl = handles.front();
 150                         handles.pop_front();
 151                 }
 152                 return curl;
 153         }
 154         void free(CURL *handle)
 155         {
 156                 if (handle)
 157                         handles.push_back(handle);
 158         }
 159 };
 160
 161 struct HTTPFetchOngoing
 162 {
 163         CurlHandlePool *pool;
 164         CURL *curl;
 165         CURLM *multi;
 166         HTTPFetchRequest request;
 167         HTTPFetchResult result;
 168         std::ostringstream oss;
 169         char *post_fields;
 170         struct curl_slist *httpheader;
 171
 172         HTTPFetchOngoing(HTTPFetchRequest request_, CurlHandlePool *pool_):
 173                 pool(pool_),
 174                 curl(NULL),
 175                 multi(NULL),
 176                 request(request_),
 177                 result(request_),
 178                 oss(std::ios::binary),
 179                 httpheader(NULL)
 180         {
 181                 curl = pool->alloc();
 182                 if (curl != NULL) {
 183                         // Set static cURL options
 184                         curl_easy_setopt(curl, CURLOPT_NOSIGNAL, 1);
 185                         curl_easy_setopt(curl, CURLOPT_FAILONERROR, 1);
 186                         curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1);
 187                         curl_easy_setopt(curl, CURLOPT_MAXREDIRS, 1);
 188
 189 #if LIBCURL_VERSION_NUM >= 0x071304
 190                         // Restrict protocols so that curl vulnerabilities in
 191                         // other protocols don't affect us.
 192                         // These settings were introduced in curl 7.19.4.
 193                         long protocols =
 194                                 CURLPROTO_HTTP |
 195                                 CURLPROTO_HTTPS |
 196                                 CURLPROTO_FTP |
 197                                 CURLPROTO_FTPS;
 198                         curl_easy_setopt(curl, CURLOPT_PROTOCOLS, protocols);
 199                         curl_easy_setopt(curl, CURLOPT_REDIR_PROTOCOLS, protocols);
 200 #endif
 201
 202                         // Set cURL options based on HTTPFetchRequest
 203                         curl_easy_setopt(curl, CURLOPT_URL,
 204                                         request.url.c_str());
 205                         curl_easy_setopt(curl, CURLOPT_TIMEOUT_MS,
 206                                         request.timeout);
 207                         curl_easy_setopt(curl, CURLOPT_CONNECTTIMEOUT_MS,
 208                                         request.connect_timeout);
 209
 210                         if (request.useragent != "")
 211                                 curl_easy_setopt(curl, CURLOPT_USERAGENT, request.useragent.c_str());
 212
 213                         // Set up a write callback that writes to the
 214                         // ostringstream ongoing->oss, unless the data
 215                         // is to be discarded
 216                         if (request.caller == HTTPFETCH_DISCARD) {
 217                                 curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION,
 218                                                 httpfetch_discardfunction);
 219                                 curl_easy_setopt(curl, CURLOPT_WRITEDATA, NULL);
 220                         }
 221                         else {
 222                                 curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION,
 223                                                 httpfetch_writefunction);
 224                                 curl_easy_setopt(curl, CURLOPT_WRITEDATA, &oss);
 225                         }
 226                         // Set POST (or GET) data
 227                         if (request.post_fields.empty()) {
 228                                 curl_easy_setopt(curl, CURLOPT_HTTPGET, 1);
 229                         }
 230                         else {
 231                                 curl_easy_setopt(curl, CURLOPT_POST, 1);
 232                                 curl_easy_setopt(curl, CURLOPT_POSTFIELDSIZE,
 233                                                 request.post_fields.size());
 234                                 curl_easy_setopt(curl, CURLOPT_POSTFIELDS,
 235                                                 request.post_fields.c_str());
 236                                 // request.post_fields must now *never* be
 237                                 // modified until CURLOPT_POSTFIELDS is cleared
 238                         }
 239                         // Set additional HTTP headers
 240                         for (size_t i = 0; i < request.extra_headers.size(); ++i) {
 241                                 httpheader = curl_slist_append(
 242                                         httpheader,
 243                                         request.extra_headers[i].c_str());
 244                         }
 245                         curl_easy_setopt(curl, CURLOPT_HTTPHEADER, httpheader);
 246                 }
 247         }
 248
 249         CURLcode start(CURLM *multi_)
 250         {
 251                 if (curl == NULL)
 252                         return CURLE_FAILED_INIT;
 253
 254                 if (multi_) {
 255                         // Multi interface (async)
 256                         CURLMcode mres = curl_multi_add_handle(multi_, curl);
 257                         if (mres != CURLM_OK) {
 258                                 errorstream<<"curl_multi_add_handle"
 259                                         <<" returned error code "<<mres
 260                                         <<std::endl;
 261                                 return CURLE_FAILED_INIT;
 262                         }
 263                         multi = multi_; // store for curl_multi_remove_handle
 264                         return CURLE_OK;
 265                 }
 266                 else {
 267                         // Easy interface (sync)
 268                         return curl_easy_perform(curl);
 269                 }
 270         }
 271
 272         void complete(CURLcode res)
 273         {
 274                 result.succeeded = (res == CURLE_OK);
 275                 result.timeout = (res == CURLE_OPERATION_TIMEDOUT);
 276                 result.data = oss.str();
 277
 278                 // Get HTTP/FTP response code
 279                 result.response_code = 0;
 280                 if (curl != NULL) {
 281                         if (curl_easy_getinfo(curl, CURLINFO_RESPONSE_CODE,
 282                                         &result.response_code) != CURLE_OK) {
 283                                 result.response_code = 0;
 284                         }
 285                 }
 286
 287                 if (res != CURLE_OK) {
 288                         infostream<<request.url<<" not found ("
 289                                 <<curl_easy_strerror(res)<<")"
 290                                 <<" (response code "<<result.response_code<<")"
 291                                 <<std::endl;
 292                 }
 293         }
 294
 295         ~HTTPFetchOngoing()
 296         {
 297                 if (multi != NULL) {
 298                         CURLMcode mres = curl_multi_remove_handle(multi, curl);
 299                         if (mres != CURLM_OK) {
 300                                 errorstream<<"curl_multi_remove_handle"
 301                                         <<" returned error code "<<mres
 302                                         <<std::endl;
 303                         }
 304                 }
 305
 306                 // Set safe options for the reusable cURL handle
 307                 curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION,
 308                                 httpfetch_discardfunction);
 309                 curl_easy_setopt(curl, CURLOPT_WRITEDATA, NULL);
 310                 curl_easy_setopt(curl, CURLOPT_POSTFIELDS, NULL);
 311                 if (httpheader != NULL) {
 312                         curl_easy_setopt(curl, CURLOPT_HTTPHEADER, NULL);
 313                         curl_slist_free_all(httpheader);
 314                 }
 315
 316                 // Store the cURL handle for reuse
 317                 pool->free(curl);
 318         }
 319 };
 320
 321 class CurlFetchThread : public SimpleThread
 322 {
 323 protected:
 324         enum RequestType {
 325                 RT_FETCH,
 326                 RT_CLEAR,
 327                 RT_WAKEUP,
 328         };
 329
 330         struct Request {
 331                 RequestType type;
 332                 HTTPFetchRequest fetchrequest;
 333                 Event *event;
 334         };
 335
 336         CURLM *m_multi;
 337         MutexedQueue<Request> m_requests;
 338         size_t m_parallel_limit;
 339
 340         // Variables exclusively used within thread
 341         std::vector<HTTPFetchOngoing*> m_all_ongoing;
 342         std::list<HTTPFetchRequest> m_queued_fetches;
 343
 344 public:
 345         CurlFetchThread(int parallel_limit)
 346         {
 347                 if (parallel_limit >= 1)
 348                         m_parallel_limit = parallel_limit;
 349                 else
 350                         m_parallel_limit = 1;
 351         }
 352
 353         void requestFetch(const HTTPFetchRequest &fetchrequest)
 354         {
 355                 Request req;
 356                 req.type = RT_FETCH;
 357                 req.fetchrequest = fetchrequest;
 358                 req.event = NULL;
 359                 m_requests.push_back(req);
 360         }
 361
 362         void requestClear(unsigned long caller, Event *event)
 363         {
 364                 Request req;
 365                 req.type = RT_CLEAR;
 366                 req.fetchrequest.caller = caller;
 367                 req.event = event;
 368                 m_requests.push_back(req);
 369         }
 370
 371         void requestWakeUp()
 372         {
 373                 Request req;
 374                 req.type = RT_WAKEUP;
 375                 req.event = NULL;
 376                 m_requests.push_back(req);
 377         }
 378
 379 protected:
 380         // Handle a request from some other thread
 381         // E.g. new fetch; clear fetches for one caller; wake up
 382         void processRequest(const Request &req)
 383         {
 384                 if (req.type == RT_FETCH) {
 385                         // New fetch, queue until there are less
 386                         // than m_parallel_limit ongoing fetches
 387                         m_queued_fetches.push_back(req.fetchrequest);
 388
 389                         // see processQueued() for what happens next
 390
 391                 }
 392                 else if (req.type == RT_CLEAR) {
 393                         unsigned long caller = req.fetchrequest.caller;
 394
 395                         // Abort all ongoing fetches for the caller
 396                         for (std::vector<HTTPFetchOngoing*>::iterator
 397                                         it = m_all_ongoing.begin();
 398                                         it != m_all_ongoing.end();) {
 399                                 if ((*it)->request.caller == caller) {
 400                                         delete (*it);
 401                                         it = m_all_ongoing.erase(it);
 402                                 }
 403                                 else
 404                                         ++it;
 405                         }
 406
 407                         // Also abort all queued fetches for the caller
 408                         for (std::list<HTTPFetchRequest>::iterator
 409                                         it = m_queued_fetches.begin();
 410                                         it != m_queued_fetches.end();) {
 411                                 if ((*it).caller == caller)
 412                                         it = m_queued_fetches.erase(it);
 413                                 else
 414                                         ++it;
 415                         }
 416                 }
 417                 else if (req.type == RT_WAKEUP) {
 418                         // Wakeup: Nothing to do, thread is awake at this point
 419                 }
 420
 421                 if (req.event != NULL)
 422                         req.event->signal();
 423         }
 424
 425         // Start new ongoing fetches if m_parallel_limit allows
 426         void processQueued(CurlHandlePool *pool)
 427         {
 428                 while (m_all_ongoing.size() < m_parallel_limit &&
 429                                 !m_queued_fetches.empty()) {
 430                         HTTPFetchRequest request = m_queued_fetches.front();
 431                         m_queued_fetches.pop_front();
 432
 433                         // Create ongoing fetch data and make a cURL handle
 434                         // Set cURL options based on HTTPFetchRequest
 435                         HTTPFetchOngoing *ongoing =
 436                                 new HTTPFetchOngoing(request, pool);
 437
 438                         // Initiate the connection (curl_multi_add_handle)
 439                         CURLcode res = ongoing->start(m_multi);
 440                         if (res == CURLE_OK) {
 441                                 m_all_ongoing.push_back(ongoing);
 442                         }
 443                         else {
 444                                 ongoing->complete(res);
 445                                 httpfetch_deliver_result(ongoing->result);
 446                                 delete ongoing;
 447                         }
 448                 }
 449         }
 450
 451         // Process CURLMsg (indicates completion of a fetch)
 452         void processCurlMessage(CURLMsg *msg)
 453         {
 454                 // Determine which ongoing fetch the message pertains to
 455                 size_t i = 0;
 456                 bool found = false;
 457                 for (i = 0; i < m_all_ongoing.size(); ++i) {
 458                         if (m_all_ongoing[i]->curl == msg->easy_handle) {
 459                                 found = true;
 460                                 break;
 461                         }
 462                 }
 463                 if (msg->msg == CURLMSG_DONE && found) {
 464                         // m_all_ongoing[i] succeeded or failed.
 465                         HTTPFetchOngoing *ongoing = m_all_ongoing[i];
 466                         ongoing->complete(msg->data.result);
 467                         httpfetch_deliver_result(ongoing->result);
 468                         delete ongoing;
 469                         m_all_ongoing.erase(m_all_ongoing.begin() + i);
 470                 }
 471         }
 472
 473         // Wait for a request from another thread, or timeout elapses
 474         void waitForRequest(long timeout)
 475         {
 476                 if (m_queued_fetches.empty()) {
 477                         try {
 478                                 Request req = m_requests.pop_front(timeout);
 479                                 processRequest(req);
 480                         }
 481                         catch (ItemNotFoundException &e) {}
 482                 }
 483         }
 484
 485         // Wait until some IO happens, or timeout elapses
 486         void waitForIO(long timeout)
 487         {
 488                 fd_set read_fd_set;
 489                 fd_set write_fd_set;
 490                 fd_set exc_fd_set;
 491                 int max_fd;
 492                 long select_timeout = -1;
 493                 struct timeval select_tv;
 494                 CURLMcode mres;
 495
 496                 FD_ZERO(&read_fd_set);
 497                 FD_ZERO(&write_fd_set);
 498                 FD_ZERO(&exc_fd_set);
 499
 500                 mres = curl_multi_fdset(m_multi, &read_fd_set,
 501                                 &write_fd_set, &exc_fd_set, &max_fd);
 502                 if (mres != CURLM_OK) {
 503                         errorstream<<"curl_multi_fdset"
 504                                 <<" returned error code "<<mres
 505                                 <<std::endl;
 506                         select_timeout = 0;
 507                 }
 508
 509                 mres = curl_multi_timeout(m_multi, &select_timeout);
 510                 if (mres != CURLM_OK) {
 511                         errorstream<<"curl_multi_timeout"
 512                                 <<" returned error code "<<mres
 513                                 <<std::endl;
 514                         select_timeout = 0;
 515                 }
 516
 517                 // Limit timeout so new requests get through
 518                 if (select_timeout < 0 || select_timeout > timeout)
 519                         select_timeout = timeout;
 520
 521                 if (select_timeout > 0) {
 522                         select_tv.tv_sec = select_timeout / 1000;
 523                         select_tv.tv_usec = (select_timeout % 1000) * 1000;
 524                         int retval = select(max_fd + 1, &read_fd_set,
 525                                         &write_fd_set, &exc_fd_set,
 526                                         &select_tv);
 527                         if (retval == -1) {
 528                                 #ifdef _WIN32
 529                                 errorstream<<"select returned error code "
 530                                         <<WSAGetLastError()<<std::endl;
 531                                 #else
 532                                 errorstream<<"select returned error code "
 533                                         <<errno<<std::endl;
 534                                 #endif
 535                         }
 536                 }
 537         }
 538
 539         void * Thread()
 540         {
 541                 ThreadStarted();
 542                 log_register_thread("CurlFetchThread");
 543                 DSTACK(__FUNCTION_NAME);
 544
 545                 CurlHandlePool pool;
 546
 547                 m_multi = curl_multi_init();
 548                 if (m_multi == NULL) {
 549                         errorstream<<"curl_multi_init returned NULL\n";
 550                         return NULL;
 551                 }
 552
 553                 assert(m_all_ongoing.empty());
 554
 555                 while (getRun()) {
 556                         BEGIN_DEBUG_EXCEPTION_HANDLER
 557
 558                         /*
 559                                 Handle new async requests
 560                         */
 561
 562                         while (!m_requests.empty()) {
 563                                 Request req = m_requests.pop_front();
 564                                 processRequest(req);
 565                         }
 566                         processQueued(&pool);
 567
 568                         /*
 569                                 Handle ongoing async requests
 570                         */
 571
 572                         int still_ongoing = 0;
 573                         while (curl_multi_perform(m_multi, &still_ongoing) ==
 574                                         CURLM_CALL_MULTI_PERFORM)
 575                                 /* noop */;
 576
 577                         /*
 578                                 Handle completed async requests
 579                         */
 580                         if (still_ongoing < (int) m_all_ongoing.size()) {
 581                                 CURLMsg *msg;
 582                                 int msgs_in_queue;
 583                                 msg = curl_multi_info_read(m_multi, &msgs_in_queue);
 584                                 while (msg != NULL) {
 585                                         processCurlMessage(msg);
 586                                         msg = curl_multi_info_read(m_multi, &msgs_in_queue);
 587                                 }
 588                         }
 589
 590                         /*
 591                                 If there are ongoing requests, wait for data
 592                                 (with a timeout of 100ms so that new requests
 593                                 can be processed).
 594
 595                                 If no ongoing requests, wait for a new request.
 596                                 (Possibly an empty request that signals
 597                                 that the thread should be stopped.)
 598                         */
 599                         if (m_all_ongoing.empty())
 600                                 waitForRequest(100000000);
 601                         else
 602                                 waitForIO(100);
 603
 604                         END_DEBUG_EXCEPTION_HANDLER(errorstream)
 605                 }
 606
 607                 // Call curl_multi_remove_handle and cleanup easy handles
 608                 for (size_t i = 0; i < m_all_ongoing.size(); ++i) {
 609                         delete m_all_ongoing[i];
 610                 }
 611                 m_all_ongoing.clear();
 612
 613                 m_queued_fetches.clear();
 614
 615                 CURLMcode mres = curl_multi_cleanup(m_multi);
 616                 if (mres != CURLM_OK) {
 617                         errorstream<<"curl_multi_cleanup"
 618                                 <<" returned error code "<<mres
 619                                 <<std::endl;
 620                 }
 621
 622                 return NULL;
 623         }
 624 };
 625
 626 CurlFetchThread *g_httpfetch_thread = NULL;
 627
 628 void httpfetch_init(int parallel_limit)
 629 {
 630         verbosestream<<"httpfetch_init: parallel_limit="<<parallel_limit
 631                         <<std::endl;
 632
 633         CURLcode res = curl_global_init(CURL_GLOBAL_DEFAULT);
 634         assert(res == CURLE_OK);
 635
 636         g_httpfetch_thread = new CurlFetchThread(parallel_limit);
 637 }
 638
 639 void httpfetch_cleanup()
 640 {
 641         verbosestream<<"httpfetch_cleanup: cleaning up"<<std::endl;
 642
 643         g_httpfetch_thread->setRun(false);
 644         g_httpfetch_thread->requestWakeUp();
 645         g_httpfetch_thread->stop();
 646         delete g_httpfetch_thread;
 647
 648         curl_global_cleanup();
 649 }
 650
 651 void httpfetch_async(const HTTPFetchRequest &fetchrequest)
 652 {
 653         g_httpfetch_thread->requestFetch(fetchrequest);
 654         if (!g_httpfetch_thread->IsRunning())
 655                 g_httpfetch_thread->Start();
 656 }
 657
 658 static void httpfetch_request_clear(unsigned long caller)
 659 {
 660         if (g_httpfetch_thread->IsRunning()) {
 661                 Event event;
 662                 g_httpfetch_thread->requestClear(caller, &event);
 663                 event.wait();
 664         }
 665         else {
 666                 g_httpfetch_thread->requestClear(caller, NULL);
 667         }
 668 }
 669
 670 void httpfetch_sync(const HTTPFetchRequest &fetchrequest,
 671                 HTTPFetchResult &fetchresult)
 672 {
 673         // Create ongoing fetch data and make a cURL handle
 674         // Set cURL options based on HTTPFetchRequest
 675         CurlHandlePool pool;
 676         HTTPFetchOngoing ongoing(fetchrequest, &pool);
 677         // Do the fetch (curl_easy_perform)
 678         CURLcode res = ongoing.start(NULL);
 679         // Update fetchresult
 680         ongoing.complete(res);
 681         fetchresult = ongoing.result;
 682 }
 683
 684 #else  // USE_CURL
 685
 686 /*
 687         USE_CURL is off:
 688
 689         Dummy httpfetch implementation that always returns an error.
 690 */
 691
 692 void httpfetch_init(int parallel_limit)
 693 {
 694 }
 695
 696 void httpfetch_cleanup()
 697 {
 698 }
 699
 700 void httpfetch_async(const HTTPFetchRequest &fetchrequest)
 701 {
 702         errorstream<<"httpfetch_async: unable to fetch "<<fetchrequest.url
 703                         <<" because USE_CURL=0"<<std::endl;
 704
 705         HTTPFetchResult fetchresult(fetchrequest); // sets succeeded = false etc.
 706         httpfetch_deliver_result(fetchresult);
 707 }
 708
 709 static void httpfetch_request_clear(unsigned long caller)
 710 {
 711 }
 712
 713 void httpfetch_sync(const HTTPFetchRequest &fetchrequest,
 714                 HTTPFetchResult &fetchresult)
 715 {
 716         errorstream<<"httpfetch_sync: unable to fetch "<<fetchrequest.url
 717                         <<" because USE_CURL=0"<<std::endl;
 718
 719         fetchresult = HTTPFetchResult(fetchrequest); // sets succeeded = false etc.
 720 }
 721
 722 #endif  // USE_CURL