Merge bitcoin/bitcoin#26033: [23.x] Prevent data race for `pathHandlers`

38d4601fe826069ee43b341e9d467beb7d14b5f0 Prevent data race for `pathHandlers` (Hennadii Stepanov)

Pull request description:

  Backport of https://github.com/bitcoin/bitcoin/pull/25983 to the 23.x branch.

ACKs for top commit:
  dergoegge:
    ACK 38d4601fe826069ee43b341e9d467beb7d14b5f0

Tree-SHA512: b235d6d2cb374baf1b54c09f4cd2feca7b6c1588d081532e987fd5def8ed0dee4b8255112b130a77aca633ec6a63cfd81f215b2e7a403c213eb6048a54774d26

1 files changed, 5 insertions, 1 deletions

diff --git a/src/httpserver.cpp b/src/httpserver.cpp
index e00c68585e..022703e79d 100644
--- a/src/httpserver.cpp
+++ b/src/httpserver.cpp
@@ -143,7 +143,8 @@ static std::vector<CSubNet> rpc_allow_subnets;
 //! Work queue for handling longer requests off the event loop thread
 static std::unique_ptr<WorkQueue<HTTPClosure>> g_work_queue{nullptr};
 //! Handlers for (sub)paths
-static std::vector<HTTPPathHandler> pathHandlers;
+static Mutex g_httppathhandlers_mutex;
+static std::vector<HTTPPathHandler> pathHandlers GUARDED_BY(g_httppathhandlers_mutex);
 //! Bound listening sockets
 static std::vector<evhttp_bound_socket *> boundSockets;
 
@@ -244,6 +245,7 @@ static void http_request_cb(struct evhttp_request* req, void* arg)
     // Find registered handler for prefix
     std::string strURI = hreq->GetURI();
     std::string path;
+    LOCK(g_httppathhandlers_mutex);
     std::vector<HTTPPathHandler>::const_iterator i = pathHandlers.begin();
     std::vector<HTTPPathHandler>::const_iterator iend = pathHandlers.end();
     for (; i != iend; ++i) {
@@ -642,11 +644,13 @@ HTTPRequest::RequestMethod HTTPRequest::GetRequestMethod() const
 void RegisterHTTPHandler(const std::string &prefix, bool exactMatch, const HTTPRequestHandler &handler)
 {
     LogPrint(BCLog::HTTP, "Registering HTTP handler for %s (exactmatch %d)\n", prefix, exactMatch);
+    LOCK(g_httppathhandlers_mutex);
     pathHandlers.push_back(HTTPPathHandler(prefix, exactMatch, handler));
 }
 
 void UnregisterHTTPHandler(const std::string &prefix, bool exactMatch)
 {
+    LOCK(g_httppathhandlers_mutex);
     std::vector<HTTPPathHandler>::iterator i = pathHandlers.begin();
     std::vector<HTTPPathHandler>::iterator iend = pathHandlers.end();
     for (; i != iend; ++i)