HTTPServer: start an I/O loop in a new thread and accept connections

Socket handling methods are copied from CConnMan:

`CConnman::GenerateWaitSockets()`
`CConnman::SocketHandlerListening()`
`CConnman::ThreadSocketHandler()` and `CConnman::SocketHandler()` are combined into ThreadSocketHandler()`.

Co-authored-by: Vasil Dimov <vd@FreeBSD.org>

src/test/httpserver_tests.cpp

@@ -11,6 +11,7 @@
 #include <boost/test/unit_test.hpp>
 
 using http_bitcoin::HTTPHeaders;
+using http_bitcoin::HTTPRemoteClient;
 using http_bitcoin::HTTPRequest;
 using http_bitcoin::HTTPResponse;
 using http_bitcoin::HTTPServer;
@@ -396,14 +397,35 @@ BOOST_AUTO_TEST_CASE(http_server_socket_tests)
     // We are bound and listening
     BOOST_REQUIRE_EQUAL(server.GetListeningSocketCount(), 1);
 
-    // Pick up the phone, there's no one there
-    CService addr_connection;
-    BOOST_REQUIRE(!server.AcceptConnectionFromListeningSocket(addr_connection));
+    // Start the I/O loop
+    server.StartSocketsThreads();
+
+    // No connections yet
+    BOOST_CHECK_EQUAL(server.GetConnectionsCount(), 0);
 
     // Create a mock client and add it to the local CreateSock queue
     ConnectClient();
-    // Accept the connection
-    BOOST_REQUIRE(server.AcceptConnectionFromListeningSocket(addr_connection));
-    BOOST_CHECK_EQUAL(addr_connection.ToStringAddrPort(), "5.5.5.5:6789");
+
+    // Wait up to a minute to find and connect the client in the I/O loop
+    int attempts{6000};
+    while (server.GetConnectionsCount() < 1) {
+        std::this_thread::sleep_for(10ms);
+        BOOST_REQUIRE(--attempts > 0);
+    }
+
+    // Inspect the connection
+    const HTTPRemoteClient& client = server.GetFirstConnection();
+    BOOST_CHECK_EQUAL(client.m_origin, "5.5.5.5:6789");
+
+    // Stop the I/O thread before modifying m_connected. CloseConnection() is a
+    // temporary test-only API that is not thread-safe against GenerateWaitSockets(),
+    // which iterates m_connected on the I/O thread.
+    server.InterruptNet();
+    server.JoinSocketsThreads();
+    // Close connection
+    BOOST_REQUIRE(server.CloseConnection(client));
+    // Close all listening sockets
+    server.StopListening();
 }
+
 BOOST_AUTO_TEST_SUITE_END()