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PIV - read just length of object to get size

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card-piv.c tries to read the first 8 bytes of an object to get object size
so it can allocate a buffer. It then reads the whole object. apdu.c has changed
over the years, and apdu.c will keep reading as long as the card returns
status of 61 XX  thus apdu.c will read the whole object while discarding
the extra data and returning to the caller only the first part of the data.
This in effect causes a double read of objects.

This patch sets SC_APDU_FLAGS_NO_GET_RESP to tell apdu to stop doing the
extra get-response commands thus avoiding most of the extra overhead.

This in not an optimal patch as it only works with T=1 cards/readers
but the patch is confined to just card-piv.c.
A better patch is in the works.

Fixes #462
This commit is contained in:
Doug Engert 2015-05-12 12:59:37 -05:00 committed by Viktor Tarasov
parent 72b5d8fe9a
commit c7af08c68a
1 changed files with 9 additions and 1 deletions
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10
src/libopensc/card-piv.c
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@ -441,6 +441,7 @@ static int piv_general_io(sc_card_t *card, int ins, int p1, int p2,
unsigned int cla_out, tag_out;
const u8 *body;
size_t bodylen;
int find_len = 0;
SC_FUNC_CALLED(card->ctx, SC_LOG_DEBUG_VERBOSE);
@ -465,6 +466,11 @@ static int piv_general_io(sc_card_t *card, int ins, int p1, int p2,
recvbuf ? SC_APDU_CASE_4_SHORT: SC_APDU_CASE_3_SHORT,
ins, p1, p2);
apdu.flags |= SC_APDU_FLAGS_CHAINING;
/* if looking for length of object, dont try and read the rest of buffer here */
if (rbuflen == 8 && card->reader->active_protocol == SC_PROTO_T1) {
apdu.flags |= SC_APDU_FLAGS_NO_GET_RESP;
find_len = 1;
}
apdu.lc = sendbuflen;
apdu.datalen = sendbuflen;
@ -493,7 +499,9 @@ static int piv_general_io(sc_card_t *card, int ins, int p1, int p2,
goto err;
}
r = sc_check_sw(card, apdu.sw1, apdu.sw2);
if (!(find_len && apdu.sw1 == 0x61)) {
r = sc_check_sw(card, apdu.sw1, apdu.sw2);
}
/* TODO: - DEE look later at tag vs size read too */
if (r < 0) {