Fix locally hosted skin servers hosted on http sometimes dropping connections

src/main/java/com/minelittlepony/hdskins/util/net/MoreHttpResponses.java

@@ -6,19 +6,22 @@
 import com.mojang.util.UUIDTypeAdapter;
 import com.google.gson.Gson;
 import com.google.gson.GsonBuilder;
+import net.minecraft.util.Util;
 import org.jetbrains.annotations.Nullable;
 
 import java.io.BufferedReader;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
 import java.lang.reflect.Type;
+import java.net.URI;
 import java.net.http.*;
 import java.net.http.HttpResponse.BodyHandlers;
 import java.nio.channels.UnresolvedAddressException;
 import java.nio.charset.StandardCharsets;
 import java.util.Optional;
 import java.util.UUID;
+import java.util.function.Function;
 import java.util.function.Supplier;
 
 /**
@@ -27,20 +30,32 @@
 @FunctionalInterface
 public interface MoreHttpResponses {
     int SC_MULTIPLE_CHOICES = 300;
-    HttpClient CLIENT = HttpClient.newHttpClient();
     Gson GSON = new GsonBuilder()
             .registerTypeAdapter(UUID.class, new UUIDTypeAdapter())
             .registerTypeHierarchyAdapter(SkinType.class, SkinType.adapter())
             .create();
 
+    Function<URI, HttpClient> HTTP_CLIENTS = Util.memoize((hostname) -> {
+        var builder = HttpClient.newBuilder();
+        // The java.net.http client defaults to using http/2 for all requests.
+        // Some servers don't behave with http/2 on an insecure local connection.
+        // So set the http version to 1.1 for those servers.
+        if ("http".equalsIgnoreCase(hostname.getScheme())) {
+            builder.version(HttpClient.Version.HTTP_1_1);
+        }
+        return builder.build();
+    });
+
     static MoreHttpResponses execute(HttpRequest.Builder request) throws IOException {
         return execute(request.build());
     }
 
     static MoreHttpResponses execute(HttpRequest request) throws IOException {
         HDSkinsServer.LOGGER.debug("Executing web request to {}", request::uri);
+        // Get a client from the url resolved to its root
+        var httpClient = HTTP_CLIENTS.apply(request.uri().resolve("/"));
         try {
-            HttpResponse<InputStream> response = CLIENT.send(request, BodyHandlers.ofInputStream());
+            HttpResponse<InputStream> response = httpClient.send(request, BodyHandlers.ofInputStream());
             return () -> response;
         } catch (InterruptedException | UnresolvedAddressException e) {
             throw new IOException(e);