lint_iban.c File Reference

Purpose

The iban linter ensures that the data conforms to the format required for an International Bank Account Number (IBAN) number.

Remarks

The format for an IBAN is specified by ISO 13616-1: Financial services - International bank account number (IBAN) - Part 1: Structure of the IBAN.

Macros
#define	IBAN_MIN_LENGTH   10
	No clear minimum length; sufficient for check characters.

Functional Description

gs1_lint_iban()

GS1_SYNTAX_DICTIONARY_API gs1_lint_err_t gs1_lint_iban	(	const char *const	data,
		size_t *const	err_pos,
		size_t *const	err_len
	)

Used to validate that an AI component conforms to the format required for an IBAN.

Parameters

[in]	data	Pointer to the null-terminated data to be linted. Must not be NULL.
[out]	err_pos	To facilitate error highlighting, the start position of the bad data is written to this pointer, if not NULL.
[out]	err_len	The length of the bad data is written to this pointer, if not NULL.

Returns

GS1_LINTER_OK if okay.

GS1_LINTER_INCORRECT_IBAN_CHECKSUM if the IBAN checksum is incorrect for the data.

GS1_LINTER_IBAN_TOO_SHORT if the data is too short to be an IBAN.

GS1_LINTER_INVALID_IBAN_CHARACTER if the data contains a character that isn't permissible within an IBAN.

GS1_LINTER_ILLEGAL_IBAN_COUNTRY_CODE if the leading two characters are not a valid ISO 3166 alpha-2 country code.

{
 
        char cc[3] = {0};
        gs1_lint_err_t ret;
        size_t len, pos;
        const char *p;
        unsigned int csum;
 
        static const char* const csetiban = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
 
        assert(data);
 
        len = strlen(data);
 
        if (len <= IBAN_MIN_LENGTH) {
                if (err_pos) *err_pos = 0;
                if (err_len) *err_len = len;
                return GS1_LINTER_IBAN_TOO_SHORT;
        }
 
        /*
         * Any character outside of the set of valid IBAN characters is illegal.
         *
         */
        if ((pos = strspn(data, csetiban)) != len) {
                if (err_pos) *err_pos = pos;
                if (err_len) *err_len = 1;
                return GS1_LINTER_INVALID_IBAN_CHARACTER;
        }
 
        /*
         *  The first two characters must be an ISO 3166 alpha-2 country code.
         *
         */
        strncpy(cc, data, 2);
        ret = gs1_lint_iso3166alpha2(cc, err_pos, err_len);
        assert(ret == GS1_LINTER_OK || ret == GS1_LINTER_NOT_ISO3166_ALPHA2);
 
        if (ret == GS1_LINTER_NOT_ISO3166_ALPHA2) {
                if (err_pos) *err_pos = 0;
                if (err_len) *err_len = 2;
                return GS1_LINTER_ILLEGAL_IBAN_COUNTRY_CODE;
        }
 
        /*
         * Compute the IBAN checksum as the sum of digits, with characters
         * converted to digits (A => 10; B => 11), starting with the forth
         * character and wrapping at the end.
         *
         */
        csum = 0;
        p = data + 4;
        do {
 
                if (*p < 'A')
                        csum = csum * 10 + (unsigned int)(*p - '0');
                else
                        csum = csum * 100 + (unsigned int)(*p - 'A' + 10);
                csum %= 97;
 
                /*
                 * Next character, wrapping at the end.
                 *
                 */
                p++;
                if (p == data + len)
                        p = data;
 
        } while (p != data + 4);
 
        /*
         * Sum (mod 97) is 1 for correctly formatted IBANs.
         *
         */
        if (csum != 1) {
                if (err_pos) *err_pos = 2;
                if (err_len) *err_len = 2;
                return GS1_LINTER_INCORRECT_IBAN_CHECKSUM;
        }
 
        return GS1_LINTER_OK;
 
}