fix extended APDUs

The extended APDU feature flag is still helpful to maintain
backwards compatibility in OpenSC.
Fix length check in UtilTLV: An extended APDU buffer can be
up to 65536 bytes long while the maximum positive value of
a short is 32767.

src/xyz/wendland/javacard/pki/isoapplet/IsoApplet.java

@@ -116,6 +116,7 @@ public class IsoApplet extends Applet implements ExtendedLength {
     private static final byte STATE_OPERATIONAL_DEACTIVATED = (byte) 0x04; // Applet usage is deactivated. (Unused at the moment.)
     private static final byte STATE_TERMINATED = (byte) 0x0C; // Applet usage is terminated. (Unused at the moment.)
 
+    private static final byte API_FEATURE_EXT_APDU = (byte) 0x01;
     private static final byte API_FEATURE_SECURE_RANDOM = (byte) 0x02;
     private static final byte API_FEATURE_ECC = (byte) 0x04;
     private static final byte API_FEATURE_RSA_SHA256_PSS = (byte) 0x08;
@@ -156,7 +157,7 @@ public static void install(byte[] bArray, short bOffset, byte bLength) {
      * \brief Only this class's install method should create the applet object.
      */
     protected IsoApplet() {
-        api_features = 0;
+        api_features = API_FEATURE_EXT_APDU;
         pin = new OwnerPIN(PIN_MAX_TRIES, PIN_MAX_LENGTH);
         fs = new IsoFileSystem();
 

src/xyz/wendland/javacard/pki/isoapplet/UtilTLV.java

@@ -182,7 +182,6 @@ public static short getLengthFieldLength(short length) throws InvalidArgumentsEx
     public static short writeTagAndLen(short tag, short len, byte[] out, short outOffset) throws InvalidArgumentsException, NotEnoughSpaceException {
         byte tagLen;
         short pos = outOffset;
-        short outLen = (short)out.length;
 
         if((short)(tag & (short)0xFF00) != 0) {
             if((short)(tag & (short)0x1F00) != (short)0x1F00) {
@@ -197,7 +196,7 @@ public static short writeTagAndLen(short tag, short len, byte[] out, short outOf
         if(len < 0) {
             throw InvalidArgumentsException.getInstance();
         }
-        if((short)(tagLen + getLengthFieldLength(len)) > (short)(outLen - outOffset)) {
+        if((int) tagLen + (int) getLengthFieldLength(len) > out.length - (int) outOffset) {
             throw NotEnoughSpaceException.getInstance();
         }