RFR 8163251 : Hard coded loop limit prevents reading of smart card data greater than 8k

[Ivan Gerasimov]

Thank you Michael!

It's a good point about maximum length.

Here's the updated webrev with the new System property dropped and the 
increased number of iterations:

http://cr.openjdk.java.net/~igerasim/8163251/01/webrev/

With kind regards,
Ivan


On 2/10/20 4:18 PM, Michael StJohns wrote:
> On 2/10/2020 6:49 PM, Ivan Gerasimov wrote:
>> Hello!
>>
>> Current implementation of the method 
>> javax.smartcardio.CardChannel.transmit() has an internal limitation 
>> on the maximum allowed amount of the transmitted data.
>>
>> This limitation is dictated by the maximum number of iterations to 
>> transmit data from a card:  Each iteration can transmit up to 256 
>> bytes of data, and we have a hardcoded limit of 32 iterations.
>>
>> Over time, we've received requests to increase this limit, as there 
>> are occasions when the effective limit of 8k is not enough.
>>
>> Would you please help review a proposal:  First, it is proposed to 
>> increase the default limit of iteration to 128 (so that up to 32k of 
>> data can be transmitted);  Second, the limit of iterations is made 
>> configurable via a System property.  This limit can be increased up 
>> to 4096 (so that the total amount of transmitted data can be made up 
>> to 1m).
>>
>> BUGURL: https://bugs.openjdk.java.net/browse/JDK-8163251
>> WEBREV: http://cr.openjdk.java.net/~igerasim/8163251/00/webrev/
>>
>> If there is an agreement on the proposal, I'll file a CSR to document 
>> a new System property.
>>
>> Thanks in advance!
>>
> Given that the maximum length for an extended APDU is 64K (65536) (hmm 
> +7 for the header and +2 for LE), and for its return is 64K + 2 
> bytes,  I'm not quite sure why you'd up the number to 4096/1M - I'd 
> set the default and fixed value to 257  (64K) and leave it at that.
>
> Mike
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-- 
With kind regards,
Ivan Gerasimov