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Export CBS_get_any_asn1_element.

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Useful for parsing things when you don't know what tag to expect (e.g. a
CHOICE). Also allow its operands to be NULL, so that it can be used to skip
arbitrary elements.

Delete CBS_ASN1_ANY which wasn't doing anything.

Change-Id: I56413e68b4f2e13860ea3e55373d5830713d7e5c
Reviewed-on: https://boringssl-review.googlesource.com/1661
Reviewed-by: Adam Langley <agl@google.com>
This commit is contained in:
David Benjamin 2014-08-27 20:19:50 -04:00 committed by Adam Langley
parent 041b58a668
commit 9b04d657be
3 changed files with 27 additions and 14 deletions
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18
crypto/bytestring/cbs.c
View File

@ -162,6 +162,12 @@ int CBS_get_any_asn1_element(CBS *cbs, CBS *out, unsigned *out_tag,
size_t *out_header_len) {
uint8_t tag, length_byte;
CBS header = *cbs;
CBS throwaway;
if (out == NULL) {
out = &throwaway;
}
if (!CBS_get_u8(&header, &tag) ||
!CBS_get_u8(&header, &length_byte)) {
return 0;
@ -172,13 +178,17 @@ int CBS_get_any_asn1_element(CBS *cbs, CBS *out, unsigned *out_tag,
return 0;
}
*out_tag = tag;
if (out_tag != NULL) {
*out_tag = tag;
}
size_t len;
if ((length_byte & 0x80) == 0) {
/* Short form length. */
len = ((size_t) length_byte) + 2;
*out_header_len = 2;
if (out_header_len != NULL) {
*out_header_len = 2;
}
} else {
/* Long form length. */
const size_t num_bytes = length_byte & 0x7f;
@ -210,7 +220,9 @@ int CBS_get_any_asn1_element(CBS *cbs, CBS *out, unsigned *out_tag,
return 0;
}
len += 2 + num_bytes;
*out_header_len = 2 + num_bytes;
if (out_header_len != NULL) {
*out_header_len = 2 + num_bytes;
}
}
return CBS_get_bytes(cbs, out, len);

9
crypto/bytestring/internal.h
View File

@ -22,15 +22,6 @@ extern "C" {
#endif
/* CBS_get_any_asn1_element sets |*out| to contain the next ASN.1 element from
* |*cbs| (including header bytes) and advances |*cbs|. It sets |*out_tag| to
* the tag number and |*out_header_len| to the length of the ASN.1 header. If
* the element has indefinite length then |*out| will only contain the header.
*
* Tag numbers greater than 31 are not supported. */
int CBS_get_any_asn1_element(CBS *cbs, CBS *out, unsigned *out_tag,
size_t *out_header_len);
/* CBS_asn1_ber_to_der reads an ASN.1 structure from |in|. If it finds
* indefinite-length elements then it attempts to convert the BER data to DER
* and sets |*out| and |*out_length| to describe a malloced buffer containing

14
include/openssl/bytestring.h
View File

@ -128,8 +128,6 @@ OPENSSL_EXPORT int CBS_get_u24_length_prefixed(CBS *cbs, CBS *out);
#define CBS_ASN1_CONSTRUCTED 0x20
#define CBS_ASN1_CONTEXT_SPECIFIC 0x80
#define CBS_ASN1_ANY 0x10000
/* CBS_get_asn1 sets |*out| to the contents of DER-encoded, ASN.1 element (not
* including tag and length bytes) and advances |cbs| over it. The ASN.1
* element must match |tag_value|. It returns one on success and zero
@ -142,6 +140,18 @@ OPENSSL_EXPORT int CBS_get_asn1(CBS *cbs, CBS *out, unsigned tag_value);
* ASN.1 header bytes too. */
OPENSSL_EXPORT int CBS_get_asn1_element(CBS *cbs, CBS *out, unsigned tag_value);
/* CBS_get_any_asn1_element sets |*out| to contain the next ASN.1 element from
* |*cbs| (including header bytes) and advances |*cbs|. It sets |*out_tag| to
* the tag number and |*out_header_len| to the length of the ASN.1 header. If
* the element has indefinite length then |*out| will only contain the
* header. Each of |out|, |out_tag|, and |out_header_len| may be NULL to ignore
* the value.
*
* Tag numbers greater than 31 are not supported. */
OPENSSL_EXPORT int CBS_get_any_asn1_element(CBS *cbs, CBS *out,
unsigned *out_tag,
size_t *out_header_len);
/* CBS_get_asn1_uint64 gets an ASN.1 INTEGER from |cbs| using |CBS_get_asn1|
* and sets |*out| to its value. It returns one on success and zero on error,
* where error includes the integer being negative, or too large to represent