Store iat in AuthData for later retrieval (#5884)

Author: Tim203

core/src/main/java/org/geysermc/geyser/session/auth/AuthData.java

@@ -27,5 +27,13 @@
 
 import java.util.UUID;
 
-public record AuthData(String name, UUID uuid, String xuid) {
+/**
+ * A class holding some basic information of the connected user.
+ *
+ * @param name The gamertag of the user
+ * @param uuid Also known as identity
+ * @param xuid The xuid of the user
+ * @param issuedAt The unix time (in seconds) that the JWT was issued
+ */
+public record AuthData(String name, UUID uuid, String xuid, long issuedAt) {
 }

core/src/main/java/org/geysermc/geyser/util/LoginEncryptionUtils.java

@@ -76,9 +76,13 @@ private static void encryptConnectionWithCert(GeyserSession session, AuthPayload
                 return;
             }
 
+            // Should always be present, but hey, why not make it safe :D
+            Long rawIssuedAt = (Long) result.rawIdentityClaims().get("iat");
+            long issuedAt = rawIssuedAt != null ? rawIssuedAt : -1;
+
             IdentityData extraData = result.identityClaims().extraData;
             // TODO!!! identity won't persist
-            session.setAuthData(new AuthData(extraData.displayName, extraData.identity, extraData.xuid));
+            session.setAuthData(new AuthData(extraData.displayName, extraData.identity, extraData.xuid, issuedAt));
             if (authPayload instanceof CertificateChainPayload certificateChainPayload) {
                 session.setCertChainData(certificateChainPayload.getChain());
             } else {