http: enclose libevent-dependent code in a namespace

diff --git a/src/httprpc.cpp b/src/httprpc.cpp
index 9a6b8eb0..2fc7f093 100644
--- a/src/httprpc.cpp
+++ b/src/httprpc.cpp
@@ -26,6 +26,8 @@
 #include <string>
 #include <vector>
 
+using http_libevent::EventBase;
+using http_libevent::HTTPRequest;
 using util::SplitString;
 using util::TrimStringView;
 
diff --git a/src/httpserver.cpp b/src/httpserver.cpp
index 2e42eb0b..367e29ca 100644
--- a/src/httpserver.cpp
+++ b/src/httpserver.cpp
@@ -46,6 +46,7 @@
 #include <support/events.h>
 
 using common::InvalidPortErrMsg;
+using http_libevent::HTTPRequest;
 
 /** Maximum size of http request (request line + headers) */
 static const size_t MAX_HEADERS_SIZE = 8192;
@@ -381,6 +382,7 @@ static void libevent_log_cb(int severity, const char *msg)
     }
 }
 
+namespace http_libevent {
 bool InitHTTPServer(const util::SignalInterrupt& interrupt)
 {
     if (!InitHTTPAllowList())
@@ -497,6 +499,7 @@ struct event_base* EventBase()
 {
     return eventBase;
 }
+} // namespace http_libevent
 
 static void httpevent_callback_fn(evutil_socket_t, short, void* data)
 {
@@ -524,6 +527,8 @@ void HTTPEvent::trigger(struct timeval* tv)
     else
         evtimer_add(ev, tv); // trigger after timeval passed
 }
+
+namespace http_libevent {
 HTTPRequest::HTTPRequest(struct evhttp_request* _req, const util::SignalInterrupt& interrupt, bool _replySent)
     : req(_req), m_interrupt(interrupt), replySent(_replySent)
 {
@@ -686,6 +691,7 @@ std::optional<std::string> GetQueryParameterFromUri(const char* uri, const std::
 
     return result;
 }
+} // namespace http_libevent
 
 void RegisterHTTPHandler(const std::string &prefix, bool exactMatch, const HTTPRequestHandler &handler)
 {
diff --git a/src/httpserver.h b/src/httpserver.h
index 76381a38..5d6ea3c8 100644
--- a/src/httpserver.h
+++ b/src/httpserver.h
@@ -30,6 +30,8 @@ static const int DEFAULT_HTTP_SERVER_TIMEOUT=30;
 struct evhttp_request;
 struct event_base;
 class CService;
+
+namespace http_libevent {
 class HTTPRequest;
 
 /** Initialize HTTP server.
@@ -48,9 +50,10 @@ void StopHTTPServer();
 
 /** Change logging level for libevent. */
 void UpdateHTTPServerLogging(bool enable);
+} // namespace http_libevent
 
 /** Handler for requests to a certain HTTP path */
-typedef std::function<void(HTTPRequest* req, const std::string &)> HTTPRequestHandler;
+typedef std::function<void(http_libevent::HTTPRequest* req, const std::string &)> HTTPRequestHandler;
 /** Register handler for prefix.
  * If multiple handlers match a prefix, the first-registered one will
  * be invoked.
@@ -59,6 +62,7 @@ void RegisterHTTPHandler(const std::string &prefix, bool exactMatch, const HTTPR
 /** Unregister handler for prefix */
 void UnregisterHTTPHandler(const std::string &prefix, bool exactMatch);
 
+namespace http_libevent {
 /** Return evhttp event base. This can be used by submodules to
  * queue timers or custom events.
  */
@@ -158,6 +162,7 @@ public:
  * @param[in] key represents the query parameter of which the value is returned
  */
 std::optional<std::string> GetQueryParameterFromUri(const char* uri, const std::string& key);
+} // namespace http_libevent
 
 /** Event class. This can be used either as a cross-thread trigger or as a timer.
  */
diff --git a/src/init.cpp b/src/init.cpp
index d2e29020..320940e4 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -145,6 +145,10 @@
 using common::InvalidPortErrMsg;
 using common::ResolveErrMsg;
 
+using http_libevent::InitHTTPServer;
+using http_libevent::InterruptHTTPServer;
+using http_libevent::StartHTTPServer;
+using http_libevent::StopHTTPServer;
 using node::ApplyArgsManOptions;
 using node::BlockManager;
 using node::CalculateCacheSizes;
diff --git a/src/rest.cpp b/src/rest.cpp
index d2c5a9b4..5321cbee 100644
--- a/src/rest.cpp
+++ b/src/rest.cpp
@@ -37,6 +37,7 @@
 
 #include <univalue.h>
 
+using http_libevent::HTTPRequest;
 using node::GetTransaction;
 using node::NodeContext;
 using util::SplitString;
diff --git a/src/rpc/node.cpp b/src/rpc/node.cpp
index 74d950ca..a43bf04d 100644
--- a/src/rpc/node.cpp
+++ b/src/rpc/node.cpp
@@ -264,7 +264,7 @@ static RPCMethod logging()
 
     // Update libevent logging if BCLog::LIBEVENT has changed.
     if (changed_log_categories & BCLog::LIBEVENT) {
-        UpdateHTTPServerLogging(LogInstance().WillLogCategory(BCLog::LIBEVENT));
+        http_libevent::UpdateHTTPServerLogging(LogInstance().WillLogCategory(BCLog::LIBEVENT));
     }
 
     UniValue result(UniValue::VOBJ);
diff --git a/src/test/fuzz/http_request.cpp b/src/test/fuzz/http_request.cpp
index 9241060b..f64fb972 100644
--- a/src/test/fuzz/http_request.cpp
+++ b/src/test/fuzz/http_request.cpp
@@ -22,11 +22,12 @@
 
 extern "C" int evhttp_parse_firstline_(struct evhttp_request*, struct evbuffer*);
 extern "C" int evhttp_parse_headers_(struct evhttp_request*, struct evbuffer*);
-
-std::string RequestMethodString(HTTPRequest::RequestMethod m);
-
 FUZZ_TARGET(http_request)
 {
+    using http_libevent::HTTPRequest;
+
+    std::string RequestMethodString(HTTPRequest::RequestMethod m);
+
     FuzzedDataProvider fuzzed_data_provider{buffer.data(), buffer.size()};
     evhttp_request* evreq = evhttp_request_new(nullptr, nullptr);
     assert(evreq != nullptr);
diff --git a/src/test/httpserver_tests.cpp b/src/test/httpserver_tests.cpp
index 030d48db..75c25caf 100644
--- a/src/test/httpserver_tests.cpp
+++ b/src/test/httpserver_tests.cpp
@@ -12,6 +12,7 @@ BOOST_FIXTURE_TEST_SUITE(httpserver_tests, BasicTestingSetup)
 
 BOOST_AUTO_TEST_CASE(test_query_parameters)
 {
+    using http_libevent::GetQueryParameterFromUri;
     std::string uri {};
 
     // No parameters