1 files changed, 39 insertions, 13 deletions

diff --git a/src/httpserver.cpp b/src/httpserver.cpp
index 86b37f79b..f6cbaa20b 100644
--- a/src/httpserver.cpp
+++ b/src/httpserver.cpp
@@ -24,6 +24,7 @@
 
 #include <event2/thread.h>
 #include <event2/buffer.h>
+#include <event2/bufferevent.h>
 #include <event2/util.h>
 #include <event2/keyvalq_struct.h>
 
@@ -40,7 +41,7 @@
 static const size_t MAX_HEADERS_SIZE = 8192;
 
 /** HTTP request work item */
-class HTTPWorkItem : public HTTPClosure
+class HTTPWorkItem final : public HTTPClosure
 {
 public:
     HTTPWorkItem(std::unique_ptr<HTTPRequest> _req, const std::string &_path, const HTTPRequestHandler& _func):
@@ -79,7 +80,7 @@ private:
     {
     public:
         WorkQueue &wq;
-        ThreadCounter(WorkQueue &w): wq(w)
+        explicit ThreadCounter(WorkQueue &w): wq(w)
         {
             std::lock_guard<std::mutex> lock(wq.cs);
             wq.numThreads += 1;
@@ -93,7 +94,7 @@ private:
     };
 
 public:
-    WorkQueue(size_t _maxDepth) : running(true),
+    explicit WorkQueue(size_t _maxDepth) : running(true),
                                  maxDepth(_maxDepth),
                                  numThreads(0)
     {
@@ -164,13 +165,13 @@ struct HTTPPathHandler
 /** HTTP module state */
 
 //! libevent event loop
-static struct event_base* eventBase = 0;
+static struct event_base* eventBase = nullptr;
 //! HTTP server
-struct evhttp* eventHTTP = 0;
+struct evhttp* eventHTTP = nullptr;
 //! List of subnets to allow RPC connections from
 static std::vector<CSubNet> rpc_allow_subnets;
 //! Work queue for handling longer requests off the event loop thread
-static WorkQueue<HTTPClosure>* workQueue = 0;
+static WorkQueue<HTTPClosure>* workQueue = nullptr;
 //! Handlers for (sub)paths
 std::vector<HTTPPathHandler> pathHandlers;
 //! Bound listening sockets
@@ -239,6 +240,16 @@ static std::string RequestMethodString(HTTPRequest::RequestMethod m)
 /** HTTP request callback */
 static void http_request_cb(struct evhttp_request* req, void* arg)
 {
+    // Disable reading to work around a libevent bug, fixed in 2.2.0.
+    if (event_get_version_number() >= 0x02010600 && event_get_version_number() < 0x02020001) {
+        evhttp_connection* conn = evhttp_request_get_connection(req);
+        if (conn) {
+            bufferevent* bev = evhttp_connection_get_bufferevent(conn);
+            if (bev) {
+                bufferevent_disable(bev, EV_READ);
+            }
+        }
+    }
     std::unique_ptr<HTTPRequest> hreq(new HTTPRequest(req));
 
     LogPrint(BCLog::HTTP, "Received a %s request for %s from %s\n",
@@ -416,7 +427,7 @@ bool InitHTTPServer()
     LogPrintf("HTTP: creating work queue of depth %d\n", workQueueDepth);
 
     workQueue = new WorkQueue<HTTPClosure>(workQueueDepth);
-    // tranfer ownership to eventBase/HTTP via .release()
+    // transfer ownership to eventBase/HTTP via .release()
     eventBase = base_ctr.release();
     eventHTTP = http_ctr.release();
     return true;
@@ -481,6 +492,8 @@ void StopHTTPServer()
     }
     if (eventBase) {
         LogPrint(BCLog::HTTP, "Waiting for HTTP event thread to exit\n");
+        // Exit the event loop as soon as there are no active events.
+        event_base_loopexit(eventBase, nullptr);
         // Give event loop a few seconds to exit (to send back last RPC responses), then break it
         // Before this was solved with event_base_loopexit, but that didn't work as expected in
         // at least libevent 2.0.21 and always introduced a delay. In libevent
@@ -495,11 +508,11 @@ void StopHTTPServer()
     }
     if (eventHTTP) {
         evhttp_free(eventHTTP);
-        eventHTTP = 0;
+        eventHTTP = nullptr;
     }
     if (eventBase) {
         event_base_free(eventBase);
-        eventBase = 0;
+        eventBase = nullptr;
     }
     LogPrint(BCLog::HTTP, "Stopped HTTP server\n");
 }
@@ -599,11 +612,24 @@ void HTTPRequest::WriteReply(int nStatus, const std::string& strReply)
     struct evbuffer* evb = evhttp_request_get_output_buffer(req);
     assert(evb);
     evbuffer_add(evb, strReply.data(), strReply.size());
-    HTTPEvent* ev = new HTTPEvent(eventBase, true,
-        std::bind(evhttp_send_reply, req, nStatus, (const char*)nullptr, (struct evbuffer *)nullptr));
-    ev->trigger(0);
+    auto req_copy = req;
+    HTTPEvent* ev = new HTTPEvent(eventBase, true, [req_copy, nStatus]{
+        evhttp_send_reply(req_copy, nStatus, nullptr, nullptr);
+        // Re-enable reading from the socket. This is the second part of the libevent
+        // workaround above.
+        if (event_get_version_number() >= 0x02010600 && event_get_version_number() < 0x02020001) {
+            evhttp_connection* conn = evhttp_request_get_connection(req_copy);
+            if (conn) {
+                bufferevent* bev = evhttp_connection_get_bufferevent(conn);
+                if (bev) {
+                    bufferevent_enable(bev, EV_READ | EV_WRITE);
+                }
+            }
+        }
+    });
+    ev->trigger(nullptr);
     replySent = true;
-    req = 0; // transferred back to main thread
+    req = nullptr; // transferred back to main thread
 }
 
 CService HTTPRequest::GetPeer()