HP Open Source Security for OpenVMS Volume 2: HP SSL for OpenVMS > CRYPTO Application
Programming Interface (API) Reference
int ASN1_STRING_length(ASN1_STRING *x);
These functions allow an ASN1_STRING structure to be manipulated.
ASN1_STRING_length() returns the length of the content of x.
ASN1_STRING_data() returns an internal pointer to the data of x. Since this is an internal pointer it should not be freed or modified in any way.
ASN1_STRING_dup() returns a copy of the structure a.
ASN1_STRING_cmp() compares a and b returning 0 if the two are identical. The string types and content are compared.
ASN1_STRING_set() sets the data of string str to the buffer data or length len. The supplied data is copied. If len is -1 then the length is determined by strlen(data).
ASN1_STRING_type() returns the type of x, using standard constants such as V_ASN1_OCTET_STRING.
ASN1_STRING_to_UTF8() converts the string in to UTF8 format, the converted data is allocated in a buffer in *out. The length of out is returned or a negative error code. The buffer *out should be free using OPENSSL_free().
Almost all ASN1 types in OpenSSL are represented as an ASN1_STRING structure. Other types such as ASN1_OCTET_STRING are simply typedefed to ASN1_STRING and the functions call the ASN1_STRING equivalents. ASN1_STRING is also used for some CHOICE types which consist entirely of primitive string types such as DirectoryString and Time.
These functions should not be used to examine or modify ASN1_INTEGER or ASN1_ENUMERATED types: the relevant INTEGER or ENUMERATED utility functions should be used instead.
In general it cannot be assumed that the data returned by ASN1_STRING_data() is null terminated or does not contain embedded nulls. The actual format of the data will depend on the actual string type itself: for example for and IA5String the data will be ASCII, for a BMPString two bytes per character in big endian format, UTF8String will be in UTF8 format.
Similar care should be take to ensure the data is in the correct format when calling ASN1_STRING_set().