Implement API for dealing with player UUIDs. Adds BUKKIT-5071

By: Travis Watkins <amaranth@ubuntu.com>

paper-server/src/main/java/org/bukkit/craftbukkit/util/MojangNameLookup.java

@@ -0,0 +1,63 @@
+package org.bukkit.craftbukkit.util;
+
+import net.minecraft.util.com.google.gson.Gson;
+import net.minecraft.util.com.google.common.base.Charsets;
+import net.minecraft.util.org.apache.commons.io.IOUtils;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.MalformedURLException;
+import java.net.URL;
+import java.net.URLConnection;
+import java.util.UUID;
+
+public class MojangNameLookup {
+    private static final Logger logger = LogManager.getFormatterLogger(MojangNameLookup.class);
+
+    public static String lookupName(UUID id) {
+        if (id == null) {
+            return null;
+        }
+
+        InputStream inputStream = null;
+        try {
+            URL url = new URL("https://sessionserver.mojang.com/session/minecraft/profile/" + id.toString().replace("-", ""));
+            URLConnection connection = url.openConnection();
+            connection.setConnectTimeout(15000);
+            connection.setReadTimeout(15000);
+            connection.setUseCaches(false);
+            inputStream = connection.getInputStream();
+            String result = IOUtils.toString(inputStream, Charsets.UTF_8);
+            Gson gson = new Gson();
+            Response response = gson.fromJson(result, Response.class);
+            if (response == null || response.name == null) {
+                logger.warn("Failed to lookup name from UUID");
+                return null;
+            }
+
+            if (response.cause != null && response.cause.length() > 0) {
+                logger.warn("Failed to lookup name from UUID: %s", response.errorMessage);
+                return null;
+            }
+
+            return response.name;
+        } catch (MalformedURLException ex) {
+            logger.warn("Malformed URL in UUID lookup");
+            return null;
+        } catch (IOException ex) {
+            IOUtils.closeQuietly(inputStream);
+        } finally {
+            IOUtils.closeQuietly(inputStream);
+        }
+
+        return null;
+    }
+
+    private class Response {
+        String errorMessage;
+        String cause;
+        String name;
+    }
+}