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author | Christian Grothoff <christian@grothoff.org> | 2021-07-30 10:38:27 +0200 |
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committer | Christian Grothoff <christian@grothoff.org> | 2021-07-30 10:38:27 +0200 |
commit | 7e669bcf6b6336ec429da949bcb4aa456971dba2 (patch) | |
tree | d19912f950d1cac1c38b857b7d5bdaba2289544e /src/reducer/validation_DE_TIN.c | |
download | anastasis-7e669bcf6b6336ec429da949bcb4aa456971dba2.tar.gz anastasis-7e669bcf6b6336ec429da949bcb4aa456971dba2.tar.bz2 anastasis-7e669bcf6b6336ec429da949bcb4aa456971dba2.zip |
folding history in preparation of GNU Anastasis v0.0.0 release
Diffstat (limited to 'src/reducer/validation_DE_TIN.c')
-rw-r--r-- | src/reducer/validation_DE_TIN.c | 57 |
1 files changed, 57 insertions, 0 deletions
diff --git a/src/reducer/validation_DE_TIN.c b/src/reducer/validation_DE_TIN.c new file mode 100644 index 0000000..9c97365 --- /dev/null +++ b/src/reducer/validation_DE_TIN.c @@ -0,0 +1,57 @@ +/* + This file is part of Anastasis + Copyright (C) 2020, 2021 Taler Systems SA + + Anastasis is free software; you can redistribute it and/or modify it under the + terms of the GNU Lesser General Public License as published by the Free Software + Foundation; either version 3, or (at your option) any later version. + + Anastasis is distributed in the hope that it will be useful, but WITHOUT ANY + WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR + A PARTICULAR PURPOSE. See the GNU General Public License for more details. + + You should have received a copy of the GNU General Public License along with + Anastasis; see the file COPYING.GPL. If not, see <http://www.gnu.org/licenses/> +*/ +/** + * @file redux/validation_DE_TIN.c + * @brief validation logic for German taxpayer identification numbers + * @author Christian Grothoff + */ +#include <string.h> +#include <stdbool.h> + + +/** + * Function to validate a German Taxpayer identification number. + * + * See https://de.wikipedia.org/wiki/Steuerliche_Identifikationsnummer + * for the structure! + * + * @param tin_number tax number to validate (input) + * @return true if validation passed, else false + */ +bool +DE_TIN_check (const char *tin_number) +{ + unsigned int csum; + unsigned int product = 10; + + if (strlen (tin_number) != 11) + return false; + for (unsigned int i = 0; i<10; i++) + { + unsigned int sum = ((tin_number[i] - '0') + product) % 10; + if (0 == sum) + sum = 10; + product = sum * 2 % 11; + } + csum = 11 - product; + if (10 == csum) + csum = 0; + if (tin_number[10] != '0' + csum) + return false; + if (tin_number[0] == '0') + return false; + return true; +} |