TXT dns record lookup for hostname pairing

src/main/java/me/youhavetrouble/inviter/dns/DNSLookup.java

@@ -0,0 +1,42 @@
+package me.youhavetrouble.inviter.dns;
+
+import me.youhavetrouble.inviter.Main;
+import org.jetbrains.annotations.NotNull;
+
+import javax.naming.directory.Attribute;
+import javax.naming.directory.Attributes;
+import javax.naming.directory.DirContext;
+import javax.naming.directory.InitialDirContext;
+import java.util.HashSet;
+import java.util.Hashtable;
+import java.util.Set;
+
+public class DNSLookup {
+
+    public static Set<String> getTxtRecords(@NotNull String hostname) throws Exception {
+        Hashtable<String, String> env = new Hashtable<>();
+        env.put("java.naming.factory.initial", "com.sun.jndi.dns.DnsContextFactory");
+        env.put("java.naming.provider.url", "dns://1.1.1.1");
+        env.put("com.sun.jndi.dns.cache.ttl", "0");
+        Set<String> txtRecords = new HashSet<>();
+
+        DirContext ctx = new InitialDirContext(env);
+        Attributes attrs = ctx.getAttributes(hostname, new String[]{"TXT"});
+        Attribute txtAttr = attrs.get("TXT");
+
+        if (txtAttr != null) {
+            for (int i = 0; i < txtAttr.size(); i++) {
+                Object record = txtAttr.get(i);
+                if (record instanceof String recordString) {
+                    txtRecords.add(recordString);
+                } else if (record instanceof byte[]) {
+                    txtRecords.add(new String((byte[]) record));
+                } else {
+                    txtRecords.add(record.toString());
+                }
+            }
+        }
+
+        return txtRecords;
+    }
+}