Merge pull request #3498 from orrche/remoteserver_accept_fix

Fix so failed accept doesn't terminate the server

docs/changelog.txt

@@ -64,6 +64,7 @@ Template for new versions:
 - `stockpiles`: hide configure and help buttons when the overlay panel is minimized
 - `caravan`: price of vermin swarms correctly adjusted down. a stack of 10000 bees is worth 10, not 10000
 - `sort`: when filtering out already-established temples in the location assignment screen, also filter out the "No specific deity" option if a non-denominational temple has already been established
+- RemoteServer: continue to accept connections as long as the listening socket is valid instead of closing the socket after the first disconnect
 
 ## Misc Improvements
 - `buildingplan`: display how many items are available on the planner panel

library/RemoteServer.cpp

@@ -51,6 +51,7 @@ POSSIBILITY OF SUCH DAMAGE.
 #include "PassiveSocket.h"
 #include "PluginManager.h"
 #include "MiscUtils.h"
+#include "Debug.h"
 
 #include <cstdio>
 #include <cstdlib>
@@ -85,6 +86,7 @@ namespace {
 }
 
 namespace DFHack {
+    DBG_DECLARE(core, socket, DebugCategory::LINFO);
 
     struct BlockGuard {
         std::lock_guard<std::mutex> lock;
@@ -476,17 +478,33 @@ void ServerMainImpl::threadFn(std::promise<bool> promise, int port)
     CActiveSocket *client = nullptr;
 
     try {
-        while ((client = server.socket.Accept()) != NULL)
+        for (int acceptFail = 0 ; server.socket.IsSocketValid() && acceptFail < 5 ; acceptFail++)
+        {
+            if ((client = server.socket.Accept()) != NULL)
             {
                 BlockGuard lock;
                 ServerConnection::Accepted(client);
                 client = nullptr;
             }
+            else
+            {
+                WARN(socket).print("Connection failure: %s (%d of %d)\n", server.socket.DescribeError(), acceptFail + 1, 5);
+            }
+        }
     } catch(BlockedException &) {
         if (client)
             client->Close();
         delete client;
     }
+
+    if (server.socket.IsSocketValid())
+    {
+        WARN(socket).print("Too many failed accepts, shutting down RemoteServer\n");
+    }
+    else
+    {
+        WARN(socket).print("Listening socket invalid, shutting down RemoteServer\n");
+    }
 }
 
 void ServerMain::block()