asn1_read_value_type - API function
int asn1_read_value_type(asn1_node root, const char *
name, void * ivalue, int * len,
unsigned int * etype);
- asn1_node root
- pointer to a structure.
- const char * name
- the name of the element inside a structure that you want to
- void * ivalue
- vector that will contain the element's content, must be a
pointer to memory cells already allocated (may be NULL).
- int * len
- number of bytes of *value: value..value[len-1]. Initialy
holds the sizeof value.
- unsigned int * etype
- The type of the value read (ASN1_ETYPE)
Returns the type and value of one element inside a structure. If an element is
OPTIONAL and this returns ASN1_ELEMENT_NOT_FOUND
, it means that this
element wasn't present in the der encoding that created the structure. The
first element of a SEQUENCE_OF or SET_OF is named "?1". The second
one "?2" and so on. If the root
provided is a node to
specific sequence element, then the keyword "?CURRENT" is also
acceptable and indicates the current sequence element of this node.
Note that there can be valid values with length zero. In these case this
function will succeed and len
will be zero.
VALUE will contain a two's complement form integer.
integer=-1 -> value=0xFF , len=1. integer=1 -> value=0x01 , len=1.
As INTEGER (but only with not negative numbers).
VALUE will be the null terminated string "TRUE" or "FALSE"
and LEN=5 or LEN=6.
OBJECT IDENTIFIER: VALUE will be a null terminated string with each number
separated by a dot (i.e. "126.96.36.1993.1").
LEN = strlen(VALUE)+1
VALUE will be a null terminated string in one of these formats:
"YYMMDDhhmmss+hh'mm'" or "YYMMDDhhmmss-hh'mm'".
VALUE will be a null terminated string in the same format used to set the value.
OCTET STRING: VALUE will contain the octet string and LEN will be the number of
VALUE will contain the generalstring and LEN will be the number of octets.
BIT STRING: VALUE will contain the bit string organized by bytes and LEN will be
the number of bits.
If NAME indicates a choice type, VALUE will specify the alternative selected.
If NAME indicates an any type, VALUE will indicate the DER encoding of the
structure actually used.
if value is returned, ASN1_ELEMENT_NOT_FOUND
is not a valid element, ASN1_VALUE_NOT_FOUND
if there isn't
any value for the element selected, and ASN1_MEM_ERROR
if The value
vector isn't big enough to store the result, and in this case len
contain the number of bytes needed.
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Copying and distribution of this file, with or without modification, are
permitted in any medium without royalty provided the copyright notice and this
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The full documentation for libtasn1
is maintained as a Texinfo manual. If
programs are properly installed at your
site, the command
- info libtasn1
should give you access to the complete manual. As an alternative you may obtain
the manual from: