asn1_read_value_type
Section: libtasn1 (3)
Updated: 4.8
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NAME
asn1_read_value_type - API function
SYNOPSIS
#include <libtasn1.h>
int asn1_read_value_type(asn1_node root, const char * name, void * ivalue, int * len, unsigned int * etype);
ARGUMENTS
- asn1_node root
-
pointer to a structure.
- const char * name
-
the name of the element inside a structure that you want to read.
- 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[0]..value[len-1]. Initialy
holds the sizeof value.
- unsigned int * etype
-
The type of the value read (ASN1_ETYPE)
DESCRIPTION
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.
INTEGER
VALUE will contain a two's complement form integer.
integer=-1 -> value[0]=0xFF , len=1.
integer=1 -> value[0]=0x01 , len=1.
ENUMERATED
As INTEGER (but only with not negative numbers).
BOOLEAN
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. "1.2.3.543.1").
LEN = strlen(VALUE)+1
UTCTIME
VALUE will be a null terminated string in one of these
formats: "YYMMDDhhmmss+hh'mm'" or "YYMMDDhhmmss-hh'mm'".
LEN=strlen(VALUE)+1.
GENERALIZEDTIME
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 octets.
GENERALSTRING
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.
CHOICE
If NAME indicates a choice type, VALUE will specify the
alternative selected.
ANY
If NAME indicates an any type, VALUE will indicate the DER
encoding of the structure actually used.
RETURNS
ASN1_SUCCESS if value is returned,
ASN1_ELEMENT_NOT_FOUND if
name 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 will contain the number of
bytes needed.
COPYRIGHT
Copyright © 2006-2015 Free Software Foundation, Inc..
Copying and distribution of this file, with or without modification,
are permitted in any medium without royalty provided the copyright
notice and this notice are preserved.
SEE ALSO
The full documentation for
libtasn1
is maintained as a Texinfo manual. If the
info
and
libtasn1
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:
-
http://www.gnu.org/software/libtasn1/manual/
Index
- NAME
-
- SYNOPSIS
-
- ARGUMENTS
-
- DESCRIPTION
-
- INTEGER
-
- ENUMERATED
-
- BOOLEAN
-
- UTCTIME
-
- GENERALIZEDTIME
-
- GENERALSTRING
-
- CHOICE
-
- ANY
-
- RETURNS
-
- COPYRIGHT
-
- SEE ALSO
-
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