lint_iban.c File Reference

Macros
#define	IBAN_MIN_LENGTH   10
	No clear minimum length; sufficient for check characters.
#define	IBAN_MAX_LENGTH   34
	Per specification.

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.

Functional Description

gs1_lint_iban()

GS1_SYNTAX_DICTIONARY_API gs1_lint_err_t gs1_lint_iban	(	const char *const	data,
		size_t	data_len,
		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 data to be linted. Must not be NULL.
[in]	data_len	Length of the data to be linted.
[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_IBAN_TOO_LONG if the data is too long 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.

{
 
        gs1_lint_err_t ret;
        size_t pos;
        unsigned int csum = 0;
        unsigned char weight;
 
        /*
         * IBAN character checksum weights (0 = invalid; weight off by 1)
         *
         */
        static const unsigned char iban_weights[256] = {
                ['0'] = 1, ['1'] = 2, ['2'] = 3, ['3'] = 4, ['4'] = 5,
                ['5'] = 6, ['6'] = 7, ['7'] = 8, ['8'] = 9, ['9'] = 10,
                ['A'] = 11, ['B'] = 12, ['C'] = 13, ['D'] = 14, ['E'] = 15,
                ['F'] = 16, ['G'] = 17, ['H'] = 18, ['I'] = 19, ['J'] = 20,
                ['K'] = 21, ['L'] = 22, ['M'] = 23, ['N'] = 24, ['O'] = 25,
                ['P'] = 26, ['Q'] = 27, ['R'] = 28, ['S'] = 29, ['T'] = 30,
                ['U'] = 31, ['V'] = 32, ['W'] = 33, ['X'] = 34, ['Y'] = 35, ['Z'] = 36
        };
 
        assert(data);
 
        /*
         * Require at least 4 characters before main loop
         *
         */
        if (GS1_LINTER_UNLIKELY(data_len < 4))
                GS1_LINTER_RETURN_ERROR(
                        GS1_LINTER_IBAN_TOO_SHORT,
                        0,
                        data_len
                );
 
        /*
         * Validate the leading two-character country code
         *
         */
        ret = gs1_lint_iso3166alpha2(data, 2, err_pos, err_len);
        assert(ret == GS1_LINTER_OK || ret == GS1_LINTER_NOT_ISO3166_ALPHA2);
        if (GS1_LINTER_UNLIKELY(ret == GS1_LINTER_NOT_ISO3166_ALPHA2))
                GS1_LINTER_RETURN_ERROR(
                        GS1_LINTER_ILLEGAL_IBAN_COUNTRY_CODE,
                        0,
                        2
                );
 
        if (GS1_LINTER_UNLIKELY(data_len > IBAN_MAX_LENGTH))
                GS1_LINTER_RETURN_ERROR(
                        GS1_LINTER_IBAN_TOO_LONG,
                        0,
                        data_len
                );
 
        if (GS1_LINTER_UNLIKELY(data_len <= IBAN_MIN_LENGTH))
                GS1_LINTER_RETURN_ERROR(
                        GS1_LINTER_IBAN_TOO_SHORT,
                        0,
                        data_len
                );
 
        /* Process characters from position 4 to end, then positions 0-3 */
        for (pos = 4; pos < data_len + 4; pos++) {
                size_t actual_pos = (pos < data_len) ? pos : (pos - data_len);
                
                weight = iban_weights[(unsigned char)data[actual_pos]];
                if (GS1_LINTER_UNLIKELY(weight == 0))
                        GS1_LINTER_RETURN_ERROR(
                                GS1_LINTER_INVALID_IBAN_CHARACTER,
                                actual_pos,
                                1
                        );
 
                csum *= weight <= 10 ? 10 : 100;
                csum += weight - 1;
                csum %= 97;
        }
 
        if (GS1_LINTER_UNLIKELY(csum != 1))
                GS1_LINTER_RETURN_ERROR(
                        GS1_LINTER_INCORRECT_IBAN_CHECKSUM,
                        2,
                        2
                );
 
        GS1_LINTER_RETURN_OK;
 
}