src/httpserver.cpp

   1 // Copyright (c) 2015-2016 The Bitcoin Core developers
   2 // Distributed under the MIT software license, see the accompanying
   3 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
   4
   5 #include <httpserver.h>
   6
   7 #include <chainparamsbase.h>
   8 #include <compat.h>
   9 #include <util.h>
  10 #include <utilstrencodings.h>
  11 #include <netbase.h>
  12 #include <rpc/protocol.h> // For HTTP status codes
  13 #include <sync.h>
  14 #include <ui_interface.h>
  15
  16 #include <stdio.h>
  17 #include <stdlib.h>
  18 #include <string.h>
  19
  20 #include <sys/types.h>
  21 #include <sys/stat.h>
  22 #include <signal.h>
  23 #include <future>
  24
  25 #include <event2/thread.h>
  26 #include <event2/buffer.h>
  27 #include <event2/bufferevent.h>
  28 #include <event2/util.h>
  29 #include <event2/keyvalq_struct.h>
  30
  31 #include <support/events.h>
  32
  33 #ifdef EVENT__HAVE_NETINET_IN_H
  34 #include <netinet/in.h>
  35 #ifdef _XOPEN_SOURCE_EXTENDED
  36 #include <arpa/inet.h>
  37 #endif
  38 #endif
  39
  40 /** Maximum size of http request (request line + headers) */
  41 static const size_t MAX_HEADERS_SIZE = 8192;
  42
  43 /** HTTP request work item */
  44 class HTTPWorkItem final : public HTTPClosure
  45 {
  46 public:
  47     HTTPWorkItem(std::unique_ptr<HTTPRequest> _req, const std::string &_path, const HTTPRequestHandler& _func):
  48         req(std::move(_req)), path(_path), func(_func)
  49     {
  50     }
  51     void operator()() override
  52     {
  53         func(req.get(), path);
  54     }
  55
  56     std::unique_ptr<HTTPRequest> req;
  57
  58 private:
  59     std::string path;
  60     HTTPRequestHandler func;
  61 };
  62
  63 /** Simple work queue for distributing work over multiple threads.
  64  * Work items are simply callable objects.
  65  */
  66 template <typename WorkItem>
  67 class WorkQueue
  68 {
  69 private:
  70     /** Mutex protects entire object */
  71     std::mutex cs;
  72     std::condition_variable cond;
  73     std::deque<std::unique_ptr<WorkItem>> queue;
  74     bool running;
  75     size_t maxDepth;
  76     int numThreads;
  77
  78     /** RAII object to keep track of number of running worker threads */
  79     class ThreadCounter
  80     {
  81     public:
  82         WorkQueue &wq;
  83         explicit ThreadCounter(WorkQueue &w): wq(w)
  84         {
  85             std::lock_guard<std::mutex> lock(wq.cs);
  86             wq.numThreads += 1;
  87         }
  88         ~ThreadCounter()
  89         {
  90             std::lock_guard<std::mutex> lock(wq.cs);
  91             wq.numThreads -= 1;
  92             wq.cond.notify_all();
  93         }
  94     };
  95
  96 public:
  97     explicit WorkQueue(size_t _maxDepth) : running(true),
  98                                  maxDepth(_maxDepth),
  99                                  numThreads(0)
 100     {
 101     }
 102     /** Precondition: worker threads have all stopped
 103      * (call WaitExit)
 104      */
 105     ~WorkQueue()
 106     {
 107     }
 108     /** Enqueue a work item */
 109     bool Enqueue(WorkItem* item)
 110     {
 111         std::unique_lock<std::mutex> lock(cs);
 112         if (queue.size() >= maxDepth) {
 113             return false;
 114         }
 115         queue.emplace_back(std::unique_ptr<WorkItem>(item));
 116         cond.notify_one();
 117         return true;
 118     }
 119     /** Thread function */
 120     void Run()
 121     {
 122         ThreadCounter count(*this);
 123         while (true) {
 124             std::unique_ptr<WorkItem> i;
 125             {
 126                 std::unique_lock<std::mutex> lock(cs);
 127                 while (running && queue.empty())
 128                     cond.wait(lock);
 129                 if (!running)
 130                     break;
 131                 i = std::move(queue.front());
 132                 queue.pop_front();
 133             }
 134             (*i)();
 135         }
 136     }
 137     /** Interrupt and exit loops */
 138     void Interrupt()
 139     {
 140         std::unique_lock<std::mutex> lock(cs);
 141         running = false;
 142         cond.notify_all();
 143     }
 144     /** Wait for worker threads to exit */
 145     void WaitExit()
 146     {
 147         std::unique_lock<std::mutex> lock(cs);
 148         while (numThreads > 0)
 149             cond.wait(lock);
 150     }
 151 };
 152
 153 struct HTTPPathHandler
 154 {
 155     HTTPPathHandler() {}
 156     HTTPPathHandler(std::string _prefix, bool _exactMatch, HTTPRequestHandler _handler):
 157         prefix(_prefix), exactMatch(_exactMatch), handler(_handler)
 158     {
 159     }
 160     std::string prefix;
 161     bool exactMatch;
 162     HTTPRequestHandler handler;
 163 };
 164
 165 /** HTTP module state */
 166
 167 //! libevent event loop
 168 static struct event_base* eventBase = nullptr;
 169 //! HTTP server
 170 struct evhttp* eventHTTP = nullptr;
 171 //! List of subnets to allow RPC connections from
 172 static std::vector<CSubNet> rpc_allow_subnets;
 173 //! Work queue for handling longer requests off the event loop thread
 174 static WorkQueue<HTTPClosure>* workQueue = nullptr;
 175 //! Handlers for (sub)paths
 176 std::vector<HTTPPathHandler> pathHandlers;
 177 //! Bound listening sockets
 178 std::vector<evhttp_bound_socket *> boundSockets;
 179
 180 /** Check if a network address is allowed to access the HTTP server */
 181 static bool ClientAllowed(const CNetAddr& netaddr)
 182 {
 183     if (!netaddr.IsValid())
 184         return false;
 185     for(const CSubNet& subnet : rpc_allow_subnets)
 186         if (subnet.Match(netaddr))
 187             return true;
 188     return false;
 189 }
 190
 191 /** Initialize ACL list for HTTP server */
 192 static bool InitHTTPAllowList()
 193 {
 194     rpc_allow_subnets.clear();
 195     CNetAddr localv4;
 196     CNetAddr localv6;
 197     LookupHost("127.0.0.1", localv4, false);
 198     LookupHost("::1", localv6, false);
 199     rpc_allow_subnets.push_back(CSubNet(localv4, 8));      // always allow IPv4 local subnet
 200     rpc_allow_subnets.push_back(CSubNet(localv6));         // always allow IPv6 localhost
 201     for (const std::string& strAllow : gArgs.GetArgs("-rpcallowip")) {
 202         CSubNet subnet;
 203         LookupSubNet(strAllow.c_str(), subnet);
 204         if (!subnet.IsValid()) {
 205             uiInterface.ThreadSafeMessageBox(
 206                 strprintf("Invalid -rpcallowip subnet specification: %s. Valid are a single IP (e.g. 1.2.3.4), a network/netmask (e.g. 1.2.3.4/255.255.255.0) or a network/CIDR (e.g. 1.2.3.4/24).", strAllow),
 207                 "", CClientUIInterface::MSG_ERROR);
 208             return false;
 209         }
 210         rpc_allow_subnets.push_back(subnet);
 211     }
 212     std::string strAllowed;
 213     for (const CSubNet& subnet : rpc_allow_subnets)
 214         strAllowed += subnet.ToString() + " ";
 215     LogPrint(BCLog::HTTP, "Allowing HTTP connections from: %s\n", strAllowed);
 216     return true;
 217 }
 218
 219 /** HTTP request method as string - use for logging only */
 220 static std::string RequestMethodString(HTTPRequest::RequestMethod m)
 221 {
 222     switch (m) {
 223     case HTTPRequest::GET:
 224         return "GET";
 225         break;
 226     case HTTPRequest::POST:
 227         return "POST";
 228         break;
 229     case HTTPRequest::HEAD:
 230         return "HEAD";
 231         break;
 232     case HTTPRequest::PUT:
 233         return "PUT";
 234         break;
 235     default:
 236         return "unknown";
 237     }
 238 }
 239
 240 /** HTTP request callback */
 241 static void http_request_cb(struct evhttp_request* req, void* arg)
 242 {
 243     // Disable reading to work around a libevent bug, fixed in 2.2.0.
 244     if (event_get_version_number() >= 0x02010600 && event_get_version_number() < 0x02020001) {
 245         evhttp_connection* conn = evhttp_request_get_connection(req);
 246         if (conn) {
 247             bufferevent* bev = evhttp_connection_get_bufferevent(conn);
 248             if (bev) {
 249                 bufferevent_disable(bev, EV_READ);
 250             }
 251         }
 252     }
 253     std::unique_ptr<HTTPRequest> hreq(new HTTPRequest(req));
 254
 255     LogPrint(BCLog::HTTP, "Received a %s request for %s from %s\n",
 256              RequestMethodString(hreq->GetRequestMethod()), hreq->GetURI(), hreq->GetPeer().ToString());
 257
 258     // Early address-based allow check
 259     if (!ClientAllowed(hreq->GetPeer())) {
 260         hreq->WriteReply(HTTP_FORBIDDEN);
 261         return;
 262     }
 263
 264     // Early reject unknown HTTP methods
 265     if (hreq->GetRequestMethod() == HTTPRequest::UNKNOWN) {
 266         hreq->WriteReply(HTTP_BADMETHOD);
 267         return;
 268     }
 269
 270     // Find registered handler for prefix
 271     std::string strURI = hreq->GetURI();
 272     std::string path;
 273     std::vector<HTTPPathHandler>::const_iterator i = pathHandlers.begin();
 274     std::vector<HTTPPathHandler>::const_iterator iend = pathHandlers.end();
 275     for (; i != iend; ++i) {
 276         bool match = false;
 277         if (i->exactMatch)
 278             match = (strURI == i->prefix);
 279         else
 280             match = (strURI.substr(0, i->prefix.size()) == i->prefix);
 281         if (match) {
 282             path = strURI.substr(i->prefix.size());
 283             break;
 284         }
 285     }
 286
 287     // Dispatch to worker thread
 288     if (i != iend) {
 289         std::unique_ptr<HTTPWorkItem> item(new HTTPWorkItem(std::move(hreq), path, i->handler));
 290         assert(workQueue);
 291         if (workQueue->Enqueue(item.get()))
 292             item.release(); /* if true, queue took ownership */
 293         else {
 294             LogPrintf("WARNING: request rejected because http work queue depth exceeded, it can be increased with the -rpcworkqueue= setting\n");
 295             item->req->WriteReply(HTTP_INTERNAL, "Work queue depth exceeded");
 296         }
 297     } else {
 298         hreq->WriteReply(HTTP_NOTFOUND);
 299     }
 300 }
 301
 302 /** Callback to reject HTTP requests after shutdown. */
 303 static void http_reject_request_cb(struct evhttp_request* req, void*)
 304 {
 305     LogPrint(BCLog::HTTP, "Rejecting request while shutting down\n");
 306     evhttp_send_error(req, HTTP_SERVUNAVAIL, nullptr);
 307 }
 308
 309 /** Event dispatcher thread */
 310 static bool ThreadHTTP(struct event_base* base, struct evhttp* http)
 311 {
 312     RenameThread("bitcoin-http");
 313     LogPrint(BCLog::HTTP, "Entering http event loop\n");
 314     event_base_dispatch(base);
 315     // Event loop will be interrupted by InterruptHTTPServer()
 316     LogPrint(BCLog::HTTP, "Exited http event loop\n");
 317     return event_base_got_break(base) == 0;
 318 }
 319
 320 /** Bind HTTP server to specified addresses */
 321 static bool HTTPBindAddresses(struct evhttp* http)
 322 {
 323     int defaultPort = gArgs.GetArg("-rpcport", BaseParams().RPCPort());
 324     std::vector<std::pair<std::string, uint16_t> > endpoints;
 325
 326     // Determine what addresses to bind to
 327     if (!gArgs.IsArgSet("-rpcallowip")) { // Default to loopback if not allowing external IPs
 328         endpoints.push_back(std::make_pair("::1", defaultPort));
 329         endpoints.push_back(std::make_pair("127.0.0.1", defaultPort));
 330         if (gArgs.IsArgSet("-rpcbind")) {
 331             LogPrintf("WARNING: option -rpcbind was ignored because -rpcallowip was not specified, refusing to allow everyone to connect\n");
 332         }
 333     } else if (gArgs.IsArgSet("-rpcbind")) { // Specific bind address
 334         for (const std::string& strRPCBind : gArgs.GetArgs("-rpcbind")) {
 335             int port = defaultPort;
 336             std::string host;
 337             SplitHostPort(strRPCBind, port, host);
 338             endpoints.push_back(std::make_pair(host, port));
 339         }
 340     } else { // No specific bind address specified, bind to any
 341         endpoints.push_back(std::make_pair("::", defaultPort));
 342         endpoints.push_back(std::make_pair("0.0.0.0", defaultPort));
 343     }
 344
 345     // Bind addresses
 346     for (std::vector<std::pair<std::string, uint16_t> >::iterator i = endpoints.begin(); i != endpoints.end(); ++i) {
 347         LogPrint(BCLog::HTTP, "Binding RPC on address %s port %i\n", i->first, i->second);
 348         evhttp_bound_socket *bind_handle = evhttp_bind_socket_with_handle(http, i->first.empty() ? nullptr : i->first.c_str(), i->second);
 349         if (bind_handle) {
 350             boundSockets.push_back(bind_handle);
 351         } else {
 352             LogPrintf("Binding RPC on address %s port %i failed.\n", i->first, i->second);
 353         }
 354     }
 355     return !boundSockets.empty();
 356 }
 357
 358 /** Simple wrapper to set thread name and run work queue */
 359 static void HTTPWorkQueueRun(WorkQueue<HTTPClosure>* queue)
 360 {
 361     RenameThread("bitcoin-httpworker");
 362     queue->Run();
 363 }
 364
 365 /** libevent event log callback */
 366 static void libevent_log_cb(int severity, const char *msg)
 367 {
 368 #ifndef EVENT_LOG_WARN
 369 // EVENT_LOG_WARN was added in 2.0.19; but before then _EVENT_LOG_WARN existed.
 370 # define EVENT_LOG_WARN _EVENT_LOG_WARN
 371 #endif
 372     if (severity >= EVENT_LOG_WARN) // Log warn messages and higher without debug category
 373         LogPrintf("libevent: %s\n", msg);
 374     else
 375         LogPrint(BCLog::LIBEVENT, "libevent: %s\n", msg);
 376 }
 377
 378 bool InitHTTPServer()
 379 {
 380     if (!InitHTTPAllowList())
 381         return false;
 382
 383     if (gArgs.GetBoolArg("-rpcssl", false)) {
 384         uiInterface.ThreadSafeMessageBox(
 385             "SSL mode for RPC (-rpcssl) is no longer supported.",
 386             "", CClientUIInterface::MSG_ERROR);
 387         return false;
 388     }
 389
 390     // Redirect libevent's logging to our own log
 391     event_set_log_callback(&libevent_log_cb);
 392     // Update libevent's log handling. Returns false if our version of
 393     // libevent doesn't support debug logging, in which case we should
 394     // clear the BCLog::LIBEVENT flag.
 395     if (!UpdateHTTPServerLogging(logCategories & BCLog::LIBEVENT)) {
 396         logCategories &= ~BCLog::LIBEVENT;
 397     }
 398
 399 #ifdef WIN32
 400     evthread_use_windows_threads();
 401 #else
 402     evthread_use_pthreads();
 403 #endif
 404
 405     raii_event_base base_ctr = obtain_event_base();
 406
 407     /* Create a new evhttp object to handle requests. */
 408     raii_evhttp http_ctr = obtain_evhttp(base_ctr.get());
 409     struct evhttp* http = http_ctr.get();
 410     if (!http) {
 411         LogPrintf("couldn't create evhttp. Exiting.\n");
 412         return false;
 413     }
 414
 415     evhttp_set_timeout(http, gArgs.GetArg("-rpcservertimeout", DEFAULT_HTTP_SERVER_TIMEOUT));
 416     evhttp_set_max_headers_size(http, MAX_HEADERS_SIZE);
 417     evhttp_set_max_body_size(http, MAX_SIZE);
 418     evhttp_set_gencb(http, http_request_cb, nullptr);
 419
 420     if (!HTTPBindAddresses(http)) {
 421         LogPrintf("Unable to bind any endpoint for RPC server\n");
 422         return false;
 423     }
 424
 425     LogPrint(BCLog::HTTP, "Initialized HTTP server\n");
 426     int workQueueDepth = std::max((long)gArgs.GetArg("-rpcworkqueue", DEFAULT_HTTP_WORKQUEUE), 1L);
 427     LogPrintf("HTTP: creating work queue of depth %d\n", workQueueDepth);
 428
 429     workQueue = new WorkQueue<HTTPClosure>(workQueueDepth);
 430     // transfer ownership to eventBase/HTTP via .release()
 431     eventBase = base_ctr.release();
 432     eventHTTP = http_ctr.release();
 433     return true;
 434 }
 435
 436 bool UpdateHTTPServerLogging(bool enable) {
 437 #if LIBEVENT_VERSION_NUMBER >= 0x02010100
 438     if (enable) {
 439         event_enable_debug_logging(EVENT_DBG_ALL);
 440     } else {
 441         event_enable_debug_logging(EVENT_DBG_NONE);
 442     }
 443     return true;
 444 #else
 445     // Can't update libevent logging if version < 02010100
 446     return false;
 447 #endif
 448 }
 449
 450 std::thread threadHTTP;
 451 std::future<bool> threadResult;
 452
 453 bool StartHTTPServer()
 454 {
 455     LogPrint(BCLog::HTTP, "Starting HTTP server\n");
 456     int rpcThreads = std::max((long)gArgs.GetArg("-rpcthreads", DEFAULT_HTTP_THREADS), 1L);
 457     LogPrintf("HTTP: starting %d worker threads\n", rpcThreads);
 458     std::packaged_task<bool(event_base*, evhttp*)> task(ThreadHTTP);
 459     threadResult = task.get_future();
 460     threadHTTP = std::thread(std::move(task), eventBase, eventHTTP);
 461
 462     for (int i = 0; i < rpcThreads; i++) {
 463         std::thread rpc_worker(HTTPWorkQueueRun, workQueue);
 464         rpc_worker.detach();
 465     }
 466     return true;
 467 }
 468
 469 void InterruptHTTPServer()
 470 {
 471     LogPrint(BCLog::HTTP, "Interrupting HTTP server\n");
 472     if (eventHTTP) {
 473         // Unlisten sockets
 474         for (evhttp_bound_socket *socket : boundSockets) {
 475             evhttp_del_accept_socket(eventHTTP, socket);
 476         }
 477         // Reject requests on current connections
 478         evhttp_set_gencb(eventHTTP, http_reject_request_cb, nullptr);
 479     }
 480     if (workQueue)
 481         workQueue->Interrupt();
 482 }
 483
 484 void StopHTTPServer()
 485 {
 486     LogPrint(BCLog::HTTP, "Stopping HTTP server\n");
 487     if (workQueue) {
 488         LogPrint(BCLog::HTTP, "Waiting for HTTP worker threads to exit\n");
 489         workQueue->WaitExit();
 490         delete workQueue;
 491         workQueue = nullptr;
 492     }
 493     if (eventBase) {
 494         LogPrint(BCLog::HTTP, "Waiting for HTTP event thread to exit\n");
 495         // Exit the event loop as soon as there are no active events.
 496         event_base_loopexit(eventBase, nullptr);
 497         // Give event loop a few seconds to exit (to send back last RPC responses), then break it
 498         // Before this was solved with event_base_loopexit, but that didn't work as expected in
 499         // at least libevent 2.0.21 and always introduced a delay. In libevent
 500         // master that appears to be solved, so in the future that solution
 501         // could be used again (if desirable).
 502         // (see discussion in https://github.com/bitcoin/bitcoin/pull/6990)
 503         if (threadResult.valid() && threadResult.wait_for(std::chrono::milliseconds(2000)) == std::future_status::timeout) {
 504             LogPrintf("HTTP event loop did not exit within allotted time, sending loopbreak\n");
 505             event_base_loopbreak(eventBase);
 506         }
 507         threadHTTP.join();
 508     }
 509     if (eventHTTP) {
 510         evhttp_free(eventHTTP);
 511         eventHTTP = nullptr;
 512     }
 513     if (eventBase) {
 514         event_base_free(eventBase);
 515         eventBase = nullptr;
 516     }
 517     LogPrint(BCLog::HTTP, "Stopped HTTP server\n");
 518 }
 519
 520 struct event_base* EventBase()
 521 {
 522     return eventBase;
 523 }
 524
 525 static void httpevent_callback_fn(evutil_socket_t, short, void* data)
 526 {
 527     // Static handler: simply call inner handler
 528     HTTPEvent *self = ((HTTPEvent*)data);
 529     self->handler();
 530     if (self->deleteWhenTriggered)
 531         delete self;
 532 }
 533
 534 HTTPEvent::HTTPEvent(struct event_base* base, bool _deleteWhenTriggered, const std::function<void(void)>& _handler):
 535     deleteWhenTriggered(_deleteWhenTriggered), handler(_handler)
 536 {
 537     ev = event_new(base, -1, 0, httpevent_callback_fn, this);
 538     assert(ev);
 539 }
 540 HTTPEvent::~HTTPEvent()
 541 {
 542     event_free(ev);
 543 }
 544 void HTTPEvent::trigger(struct timeval* tv)
 545 {
 546     if (tv == nullptr)
 547         event_active(ev, 0, 0); // immediately trigger event in main thread
 548     else
 549         evtimer_add(ev, tv); // trigger after timeval passed
 550 }
 551 HTTPRequest::HTTPRequest(struct evhttp_request* _req) : req(_req),
 552                                                        replySent(false)
 553 {
 554 }
 555 HTTPRequest::~HTTPRequest()
 556 {
 557     if (!replySent) {
 558         // Keep track of whether reply was sent to avoid request leaks
 559         LogPrintf("%s: Unhandled request\n", __func__);
 560         WriteReply(HTTP_INTERNAL, "Unhandled request");
 561     }
 562     // evhttpd cleans up the request, as long as a reply was sent.
 563 }
 564
 565 std::pair<bool, std::string> HTTPRequest::GetHeader(const std::string& hdr)
 566 {
 567     const struct evkeyvalq* headers = evhttp_request_get_input_headers(req);
 568     assert(headers);
 569     const char* val = evhttp_find_header(headers, hdr.c_str());
 570     if (val)
 571         return std::make_pair(true, val);
 572     else
 573         return std::make_pair(false, "");
 574 }
 575
 576 std::string HTTPRequest::ReadBody()
 577 {
 578     struct evbuffer* buf = evhttp_request_get_input_buffer(req);
 579     if (!buf)
 580         return "";
 581     size_t size = evbuffer_get_length(buf);
 582     /** Trivial implementation: if this is ever a performance bottleneck,
 583      * internal copying can be avoided in multi-segment buffers by using
 584      * evbuffer_peek and an awkward loop. Though in that case, it'd be even
 585      * better to not copy into an intermediate string but use a stream
 586      * abstraction to consume the evbuffer on the fly in the parsing algorithm.
 587      */
 588     const char* data = (const char*)evbuffer_pullup(buf, size);
 589     if (!data) // returns nullptr in case of empty buffer
 590         return "";
 591     std::string rv(data, size);
 592     evbuffer_drain(buf, size);
 593     return rv;
 594 }
 595
 596 void HTTPRequest::WriteHeader(const std::string& hdr, const std::string& value)
 597 {
 598     struct evkeyvalq* headers = evhttp_request_get_output_headers(req);
 599     assert(headers);
 600     evhttp_add_header(headers, hdr.c_str(), value.c_str());
 601 }
 602
 603 /** Closure sent to main thread to request a reply to be sent to
 604  * a HTTP request.
 605  * Replies must be sent in the main loop in the main http thread,
 606  * this cannot be done from worker threads.
 607  */
 608 void HTTPRequest::WriteReply(int nStatus, const std::string& strReply)
 609 {
 610     assert(!replySent && req);
 611     // Send event to main http thread to send reply message
 612     struct evbuffer* evb = evhttp_request_get_output_buffer(req);
 613     assert(evb);
 614     evbuffer_add(evb, strReply.data(), strReply.size());
 615     auto req_copy = req;
 616     HTTPEvent* ev = new HTTPEvent(eventBase, true, [req_copy, nStatus]{
 617         evhttp_send_reply(req_copy, nStatus, nullptr, nullptr);
 618         // Re-enable reading from the socket. This is the second part of the libevent
 619         // workaround above.
 620         if (event_get_version_number() >= 0x02010600 && event_get_version_number() < 0x02020001) {
 621             evhttp_connection* conn = evhttp_request_get_connection(req_copy);
 622             if (conn) {
 623                 bufferevent* bev = evhttp_connection_get_bufferevent(conn);
 624                 if (bev) {
 625                     bufferevent_enable(bev, EV_READ | EV_WRITE);
 626                 }
 627             }
 628         }
 629     });
 630     ev->trigger(nullptr);
 631     replySent = true;
 632     req = nullptr; // transferred back to main thread
 633 }
 634
 635 CService HTTPRequest::GetPeer()
 636 {
 637     evhttp_connection* con = evhttp_request_get_connection(req);
 638     CService peer;
 639     if (con) {
 640         // evhttp retains ownership over returned address string
 641         const char* address = "";
 642         uint16_t port = 0;
 643         evhttp_connection_get_peer(con, (char**)&address, &port);
 644         peer = LookupNumeric(address, port);
 645     }
 646     return peer;
 647 }
 648
 649 std::string HTTPRequest::GetURI()
 650 {
 651     return evhttp_request_get_uri(req);
 652 }
 653
 654 HTTPRequest::RequestMethod HTTPRequest::GetRequestMethod()
 655 {
 656     switch (evhttp_request_get_command(req)) {
 657     case EVHTTP_REQ_GET:
 658         return GET;
 659         break;
 660     case EVHTTP_REQ_POST:
 661         return POST;
 662         break;
 663     case EVHTTP_REQ_HEAD:
 664         return HEAD;
 665         break;
 666     case EVHTTP_REQ_PUT:
 667         return PUT;
 668         break;
 669     default:
 670         return UNKNOWN;
 671         break;
 672     }
 673 }
 674
 675 void RegisterHTTPHandler(const std::string &prefix, bool exactMatch, const HTTPRequestHandler &handler)
 676 {
 677     LogPrint(BCLog::HTTP, "Registering HTTP handler for %s (exactmatch %d)\n", prefix, exactMatch);
 678     pathHandlers.push_back(HTTPPathHandler(prefix, exactMatch, handler));
 679 }
 680
 681 void UnregisterHTTPHandler(const std::string &prefix, bool exactMatch)
 682 {
 683     std::vector<HTTPPathHandler>::iterator i = pathHandlers.begin();
 684     std::vector<HTTPPathHandler>::iterator iend = pathHandlers.end();
 685     for (; i != iend; ++i)
 686         if (i->prefix == prefix && i->exactMatch == exactMatch)
 687             break;
 688     if (i != iend)
 689     {
 690         LogPrint(BCLog::HTTP, "Unregistering HTTP handler for %s (exactmatch %d)\n", prefix, exactMatch);
 691         pathHandlers.erase(i);
 692     }
 693 }
 694
 695 std::string urlDecode(const std::string &urlEncoded) {
 696     std::string res;
 697     if (!urlEncoded.empty()) {
 698         char *decoded = evhttp_uridecode(urlEncoded.c_str(), false, nullptr);
 699         if (decoded) {
 700             res = std::string(decoded);
 701             free(decoded);
 702         }
 703     }
 704     return res;
 705 }