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ASN1_MBSTRING_COPY(3) Library Functions Manual ASN1_MBSTRING_COPY(3)

ASN1_mbstring_copy, ASN1_mbstring_ncopy, ASN1_STRING_set_by_NID, ASN1_STRING_set_default_mask, ASN1_STRING_set_default_mask_asc, ASN1_STRING_get_default_mask, ASN1_tag2bitcopy a mutibyte string into an ASN.1 string object

#include <openssl/asn1.h>

int
ASN1_mbstring_copy(ASN1_STRING **out, const unsigned char *in, int inbytes, int inform, unsigned long mask);

int
ASN1_mbstring_ncopy(ASN1_STRING **out, const unsigned char *in, int inbytes, int inform, unsigned long mask, long minchars, long maxchars);

ASN1_STRING *
ASN1_STRING_set_by_NID(ASN1_STRING **out, const unsigned char *in, int inbytes, int inform, int nid);

void
ASN1_STRING_set_default_mask(unsigned long mask);

int
ASN1_STRING_set_default_mask_asc(const char *maskname);

unsigned long
ASN1_STRING_get_default_mask(void);

unsigned long
ASN1_tag2bit(int tag);

() interprets inbytes bytes starting at in as a multibyte string and copies it to *out, optionally changing the encoding. If the inbytes argument is negative, the strlen(3) of in is used instead.

The inform argument specifies the character encoding of in:

inform encoding
ISO-Latin-1
UTF-16
UTF-32
UTF-8

The bit mask specifies a set of ASN.1 string types that the user is willing to accept:

bit in mask acceptable output type default
ASN1_PRINTABLESTRING yes
ASN1_IA5STRING no
ASN1_T61STRING yes
ASN1_BMPSTRING yes
ASN1_UNIVERSALSTRING no
any other bit ASN1_UTF8STRING yes

The first type from the above table that is included in the mask argument and that can represent in is used as the output type. The “default” column indicates whether the type is considered acceptable if the mask argument has the special value 0.

The following bit mask constants each include several of the bits listed above:

mask constant PRI IA5 T61 BMP UNI UTF8
yes no yes yes yes yes
yes no yes yes no yes
yes yes yes yes no yes

If out is NULL, inform, inbytes, and in are validated and the output type is determined and returned, but nothing is copied.

Otherwise, if *out is NULL, a new output object of the output type is allocated and a pointer to it is stored in *out.

Otherwise, **out is used as the output object. Any data already stored in it is freed and its type is changed to the output type.

Finally, in is copied to the output object, changing the character encoding if inform does not match the encoding used by the output type.

() is similar except that the number of characters in in is restricted to the range from minchars to maxchars, inclusive. If maxchars is 0, no upper limit is enforced on the number of characters.

() is similar with the following differences:

() sets the global mask used by ASN1_STRING_set_by_NID() to the mask argument.

() sets the global mask as follows:

maskname mask
"default" anything
"nombstr" anything except B_ASN1_BMPSTRING |
"pkix" anything except B_ASN1_T61STRING
"utf8only"

If the maskname argument starts with the substring "MASK:", the rest of it is interpreted as an unsigned long value using strtoul(3).

() translates ASN.1 data types to type bits as follows:

tag return value
0
0
0
0
0
0
0
11, 13, 14, 15, 29
(< 0, > 30)

In typical usage, the calling code calculates the bitwise AND of the return value and a mask describing data types that the calling code is willing to use. If the result of the AND operation is non-zero, the data type is adequate; otherwise, the calling code may need to raise an error.

ASN1_mbstring_copy() and ASN1_mbstring_ncopy() return the V_ASN1_* constant representing the output type or -1 if inform is invalid, if inbytes or in is invalid for the inform encoding, if in contains an UTF-16 surrogate, which is unsupported even for input using the UTF-16 encoding, or if memory allocation fails.

ASN1_mbstring_ncopy() also returns -1 if in contains fewer than minchars or more than maxchars characters.

ASN1_STRING_set_by_NID() returns the new or changed ASN.1 string object or NULL on failure.

ASN1_STRING_set_default_mask_asc() returns 1 if successful or 0 if "MASK:" is not followed by a number, if the number is followed by a non-numeric character, or if the maskname is invalid.

ASN1_STRING_get_default_mask() returns the global mask.

ASN1_tag2bit() returns a B_ASN1_* constant or 0.

ASN1_PRINTABLE_type(3), ASN1_STRING_new(3), ASN1_STRING_set(3), ASN1_STRING_TABLE_get(3), ASN1_UNIVERSALSTRING_to_string(3)

ASN1_mbstring_copy(), ASN1_mbstring_ncopy(), ASN1_STRING_set_by_NID(), ASN1_STRING_set_default_mask(), ASN1_STRING_set_default_mask_asc(), and ASN1_STRING_get_default_mask() first appeared in OpenSSL 0.9.5 and have been available since OpenBSD 2.7.

ASN1_tag2bit() first appeared in OpenSSL 0.9.7 and has been available since OpenBSD 3.2.

If integer overflow occurs in ASN1_STRING_set_default_mask_asc() while parsing a number following "MASK:", the function succeeds, essentially behaving in the same way as for "default".

Passing "default" to ASN1_STRING_set_default_mask_asc() does restore the default mask. Instead, passing "utf8only" does that.

December 10, 2021 OpenBSD-current