NAME

       shishi_asn1_read_optional - API function

SYNOPSIS

       #include <shishi.h>

       int  shishi_asn1_read_optional(Shishi * handle, Shishi_asn1 node, const char * field, char
       ** data, size_t * datalen);

ARGUMENTS

       Shishi * handle
                   shishi handle as allocated by shishi_init().

       Shishi_asn1 node
                   ASN.1 variable to read field from.

       const char * field
                   name of field in node to read.

       char ** data
                   newly allocated output buffer that will hold ASN.1 field data.

       size_t * datalen
                   actual size of output buffer.

DESCRIPTION

       Extract data stored in a ASN.1 field into a newly allocated buffer.  If the field does not
       exist (i.e., SHISHI_ASN1_NO_ELEMENT), this function set datalen to 0 and succeeds.  Can be
       useful to read ASN.1 fields which are marked OPTIONAL in the grammar, if you want to avoid
       special error handling in your code.

RETURN VALUE

       Returns  SHISHI_OK  if  successful,  SHISHI_ASN1_NO_VALUE  if  the  field has no value, ot
       SHISHI_ASN1_ERROR otherwise.

REPORTING BUGS

       Report     bugs     to     <bug-shishi@gnu.org>.      GNU      Shishi      home      page:
       http://www.gnu.org/software/shishi/      General      help     using     GNU     software:
       http://www.gnu.org/gethelp/

COPYRIGHT

       Copyright © 2002-2022 Simon Josefsson.
       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  shishi  is maintained as a Texinfo manual.  If the info and
       shishi programs are properly installed at your site, the command

              info shishi

       should give you access to the complete manual.