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<p>Ignore my earlier comment about fixing the check. <br>
</p>
<p>Took a second look at the check and noticed that it's for
throwing the exception.<br>
</p>
<p>Your current webrev is fine.</p>
Regards,<br>
Valerie<br>
<p><br>
</p>
<div class="moz-cite-prefix">On 2/12/2020 8:23 PM, Valerie Peng
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:3c87015d-3d01-2450-7691-42cc4f35ed26@oracle.com">
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<p>Hi, Ivan,</p>
<p><span style="left: 729.868px; top: 57.2085px; font-size:
18.4px; font-family: sans-serif; transform: scaleX(1.00278);">I
share your thought/confusion on the current impl as </span>I
am also not familiar with <span style="left: 729.868px; top:
57.2085px; font-size: 18.4px; font-family: sans-serif;
transform: scaleX(1.00278);">ISO/IEC 7816-4. <br>
</span></p>
<p><span style="left: 729.868px; top: 57.2085px; font-size:
18.4px; font-family: sans-serif; transform: scaleX(1.00278);">Based
on my reading of this standard and the CardImpl code, it looks
like the while-true loop is for retrieving additional response
data. Per the standard and javadoc, max length of the response
data is 65536. Given that SW2 is only one byte, it would
probably only return at most 256 byte response data at a time.
Thus, the iteration count would be at most 256.<br>
</span></p>
<span style="left: 729.868px; top: 57.2085px; font-size: 18.4px;
font-family: sans-serif; transform: scaleX(1.00278);"></span>
<p>So far we are on the same page. <br>
</p>
<p>With the latest webrev (webrev.01), it seems that the loop will
only be run 255 instead of 256 times as k is incremented before
comparison. Thus, I think we should fix the check.<br>
</p>
<p>Valerie<br>
</p>
<div class="moz-cite-prefix">On 2/11/2020 12:18 PM, Ivan Gerasimov
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:e1380ad6-c05c-9a40-8dd1-76049d3ed221@oracle.com">Hi
Valerie! <br>
<br>
To be honest, the all these limitations are not quite clear to
me. <br>
<br>
If the command is using an extended Le word to specify the
expected length of the response data, then this length can be at
most 65536. <br>
<br>
If a short Le was used, then the length can be at most 256. <br>
<br>
However, if we received 0x61 in the SW1, that means that more
data bytes are available and they can be retrieved by issuing
another transmit call with a short Le. This next call can again
potentially result in 0x61 in SW1, and so on. <br>
<br>
In the standard, I cannot see any explicit limitations on the
number of retries. So, I see it as it might be possible to
retrieve more data than 65536 bytes. <br>
<br>
On the other hand, in the specification for CommandAPDU [1] we
have hardcoded limit for the maximum response length, which is
65536. So, even if it were possible to retrieve larger data,
there's no point to try, as the current API prohibits it. <br>
<br>
Assuming that the 0x61 response can only be received when a
short Le is used, the maximum RESPONSE_ITERATOR should be set to
256, and an exception should be thrown once that number is
exceeded. <br>
<br>
I've updated the webrev in-place accordingly. <br>
<br>
[0] <a class="moz-txt-link-freetext"
href="http://cr.openjdk.java.net/~igerasim/8163251/01/webrev/"
moz-do-not-send="true">http://cr.openjdk.java.net/~igerasim/8163251/01/webrev/</a>
<br>
<br>
[1]
<a class="moz-txt-link-freetext"
href="https://docs.oracle.com/en/java/javase/13/docs/api/java.smartcardio/javax/smartcardio/CommandAPDU.html#%3Cinit%3E(int,int,int,int,int)"
moz-do-not-send="true">https://docs.oracle.com/en/java/javase/13/docs/api/java.smartcardio/javax/smartcardio/CommandAPDU.html#%3Cinit%3E(int,int,int,int,int)</a><br>
<br>
With kind regards, <br>
<br>
Ivan <br>
<br>
<br>
On 2/10/20 6:40 PM, Valerie Peng wrote: <br>
<blockquote type="cite">Hi Ivan, <br>
<br>
You removed the "=", so the actual iteration count is reduced
by one. <br>
<br>
Should the iteration count be 256 or 257? If the actual count
should be 257, then may be the check needs to be changed to
k++ from ++k? <br>
<br>
Valerie <br>
<br>
On 2/10/2020 5:07 PM, Ivan Gerasimov wrote: <br>
<blockquote type="cite">Thank you Michael! <br>
<br>
It's a good point about maximum length. <br>
<br>
Here's the updated webrev with the new System property
dropped and the increased number of iterations: <br>
<br>
<a class="moz-txt-link-freetext"
href="http://cr.openjdk.java.net/~igerasim/8163251/01/webrev/"
moz-do-not-send="true">http://cr.openjdk.java.net/~igerasim/8163251/01/webrev/</a>
<br>
<br>
With kind regards, <br>
Ivan <br>
<br>
<br>
On 2/10/20 4:18 PM, Michael StJohns wrote: <br>
<blockquote type="cite">On 2/10/2020 6:49 PM, Ivan Gerasimov
wrote: <br>
<blockquote type="cite">Hello! <br>
<br>
Current implementation of the method
javax.smartcardio.CardChannel.transmit() has an internal
limitation on the maximum allowed amount of the
transmitted data. <br>
<br>
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. <br>
<br>
Over time, we've received requests to increase this
limit, as there are occasions when the effective limit
of 8k is not enough. <br>
<br>
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). <br>
<br>
BUGURL: <a class="moz-txt-link-freetext"
href="https://bugs.openjdk.java.net/browse/JDK-8163251"
moz-do-not-send="true">https://bugs.openjdk.java.net/browse/JDK-8163251</a>
<br>
WEBREV: <a class="moz-txt-link-freetext"
href="http://cr.openjdk.java.net/~igerasim/8163251/00/webrev/"
moz-do-not-send="true">http://cr.openjdk.java.net/~igerasim/8163251/00/webrev/</a>
<br>
<br>
If there is an agreement on the proposal, I'll file a
CSR to document a new System property. <br>
<br>
Thanks in advance! <br>
<br>
</blockquote>
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. <br>
<br>
Mike <br>
<br>
<br>
<br>
<br>
<br>
</blockquote>
</blockquote>
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