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ASN1 cleanup part 1 

ASN1 tags are represented in two many ways within OpenSC.
This is a trivial change to simplify one aspect of this.
It also makes the code more readable.

SC_ASN1_CLASS_MASK, SC_ASN1_APP, SC_ASN1_CTX, SC_ASN1_PRV,
SC_ASN1_CONS are changed, and SC_ASN1_CLASS_MASK is added.

These then align with the bits defined by SC_ASN1_TAG_CLASS,
SC_ASN1_TAG_APPLICATION, SC_ASN1_TAG_CONTEXT, SC_ASN1_TAG_PRIVATE,
and SC_ASN1_TAG_CONSTRUCTED.

(SC_ASN1_UNI and SC_ASN1_TAG_UNIVERSAL are both 0x00 thus no change
is needed).

(No sign of a right shift of SC_ASN1_CTX or SC_ASN1_PRV causeing
problems has been seen in the code.) If found, can be solved.)

Close examination of the OpenSC code base shows all uses of tags
used by routines and sc_asn1_entry use the defines.

This could allows 26 lines of code in sc_asn1_skip_tag used to test
the 3 CLASS and CONSTRUCTED bits to be replaced by:

	if (((cla << 24) | tag) != tag_in)
		return NULL;

The 26 lines still work as will any other code in OpenSC
that tests the bits using the defines. It also allows new code
to be simplified.

Problem identified while looking at better way to check response
on GET_DATA (0xCB) that returns TLV as used in card-piv.c

Changes tested using pkcs11-tool --test --login with PIV, SC_HSM
and OpenPGP cards.
This commit is contained in:
Doug Engert 2020-07-21 10:42:26 -05:00 committed by Frank Morgner
parent 30180986a0
commit 483e153182
1 changed files with 10 additions and 5 deletions
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15
src/libopensc/asn1.h
View File

@ -127,13 +127,16 @@ int sc_asn1_sig_value_sequence_to_rs(struct sc_context *ctx,
const unsigned char *in, size_t inlen,
unsigned char *buf, size_t buflen);
#define SC_ASN1_CLASS_MASK 0x30000000
/* long form tags use these */
/* Same as SC_ASN1_TAG_* shifted left by 24 bits */
#define SC_ASN1_CLASS_MASK 0xC0000000
#define SC_ASN1_UNI 0x00000000 /* Universal */
#define SC_ASN1_APP 0x10000000 /* Application */
#define SC_ASN1_CTX 0x20000000 /* Context */
#define SC_ASN1_PRV 0x30000000 /* Private */
#define SC_ASN1_CONS 0x01000000
#define SC_ASN1_APP 0x40000000 /* Application */
#define SC_ASN1_CTX 0x80000000 /* Context */
#define SC_ASN1_PRV 0xC0000000 /* Private */
#define SC_ASN1_CONS 0x20000000
#define SC_ASN1_CLASS_CONS 0xE0000000 /* CLASS and CONS */
#define SC_ASN1_TAG_MASK 0x00FFFFFF
#define SC_ASN1_TAGNUM_SIZE 3
@ -173,6 +176,7 @@ int sc_asn1_sig_value_sequence_to_rs(struct sc_context *ctx,
/* use callback function */
#define SC_ASN1_CALLBACK 384
/* use with short one byte tags */
#define SC_ASN1_TAG_CLASS 0xC0
#define SC_ASN1_TAG_UNIVERSAL 0x00
#define SC_ASN1_TAG_APPLICATION 0x40
@ -181,6 +185,7 @@ int sc_asn1_sig_value_sequence_to_rs(struct sc_context *ctx,
#define SC_ASN1_TAG_CONSTRUCTED 0x20
#define SC_ASN1_TAG_PRIMITIVE 0x1F
#define SC_ASN1_TAG_CLASS_CONS 0xE0
#define SC_ASN1_TAG_EOC 0
#define SC_ASN1_TAG_BOOLEAN 1