I have asked someone who worked on this code and they said:
I believe this is a failsafe to prevent the code from going into an
infinite loop when talking to a bad card or driver.
--Sean
Ming Yung wrote:
Hi there,
This relates to a limitation (bug?) in the implementation of
javax.smartcardio.Channel.
I am looking at doing APDU output chaining using the "SW 61XX and GET
RESPONSE" mechanism in order to transfer large datasets out of a
JavaCard. As it stands, I am limited to chains of length 31 because of
the following condition in
sun.security.smartcardio.ChannelImpl.doTransmit(byte[] command):
int k=0;
while (true) {
if (++k >=32) {
throw new CardException("Could not obtain response");
}
....
Is there any reason for this condition? I cannot find it in ISO 7816-4
(2005 edition).
Right now, a workaround is to set the undocumented system property
"sun.security.smartcardio.t1GetResponse" to "false" (I'm using a T=1
card) and handle the chaining outside smartcardio.
Cheers,
Ming
