DLP: the detector framework, the region-free detectors, word lists and attachment text
Phase 2a of the DLP and mail flow rules spec: pure functions in crates/features/src/mailflow, nothing wired into the mail path yet. - Detectors report distinct values found, each either checked by its published check digit or counted only beside a corroborating word within 50 characters. This PR adds the region-free ones: payment cards (issuer prefixes, Luhn), IBAN (registry lengths, mod 97), SWIFT/BIC, email addresses and phone numbers in bulk, dates of birth, passport numbers, private keys and published service-token formats. Regional identifiers follow, a region per PR. - Word lists (Aho-Corasick, whole words, any case) and patterns (regex with a compiled-size limit) count occurrences. - Attachment text: text files with or without a UTF-16 mark, HTML, DOCX/XLSX/PPTX, ODT/ODS/ODP and ZIP archives one level deep, read with the zip and quick-xml crates the workspace already has. Encrypted files, PDF, legacy binary Office files, nested archives and anything past the limits come back as not inspectable, with why. 21 unit tests, against the networks' test card numbers and the IBAN registry's own examples among others.
This commit is contained in:
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/*
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* SPDX-FileCopyrightText: 2026 Coffey Labs
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*
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* SPDX-License-Identifier: AGPL-3.0-only
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*/
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//! Check-digit algorithms, each from its public definition.
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/// The Luhn check (ISO/IEC 7812-1, Annex B) over a string of ASCII digits.
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pub fn luhn(digits: &str) -> bool {
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if digits.len() < 2 || !digits.bytes().all(|b| b.is_ascii_digit()) {
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return false;
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}
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let sum: u32 = digits
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.bytes()
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.rev()
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.enumerate()
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.map(|(i, b)| {
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let d = u32::from(b - b'0');
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if i % 2 == 1 {
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let d = d * 2;
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if d > 9 { d - 9 } else { d }
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} else {
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d
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}
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})
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.sum();
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sum % 10 == 0
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}
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/// ISO 13616 IBAN lengths, by country, from the IBAN registry.
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const IBAN_LENGTHS: &[(&str, usize)] = &[
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("AD", 24),
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("AE", 23),
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("AL", 28),
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("AT", 20),
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("AZ", 28),
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("BA", 20),
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("BE", 16),
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("BG", 22),
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("BH", 22),
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("BI", 27),
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("BR", 29),
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("BY", 28),
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("CH", 21),
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("CR", 22),
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("CY", 28),
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("CZ", 24),
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("DE", 22),
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("DJ", 27),
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("DK", 18),
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("DO", 28),
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("EE", 20),
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("EG", 29),
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("ES", 24),
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("FI", 18),
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("FK", 18),
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("FO", 18),
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("FR", 27),
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("GB", 22),
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("GE", 22),
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("GI", 23),
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("GL", 18),
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("GR", 27),
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("GT", 28),
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("HN", 28),
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("HR", 21),
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("HU", 28),
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("IE", 22),
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("IL", 23),
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("IQ", 23),
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("IS", 26),
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("IT", 27),
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("JO", 30),
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("KW", 30),
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("KZ", 20),
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("LB", 28),
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("LC", 32),
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("LI", 21),
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("LT", 20),
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("LU", 20),
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("LV", 21),
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("LY", 25),
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("MC", 27),
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("MD", 24),
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("ME", 22),
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("MK", 19),
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("MN", 20),
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("MR", 27),
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("MT", 31),
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("MU", 30),
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("NI", 28),
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("NL", 18),
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("NO", 15),
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("OM", 23),
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("PK", 24),
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("PL", 28),
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("PS", 29),
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("PT", 25),
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("QA", 29),
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("RO", 24),
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("RS", 22),
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("RU", 33),
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("SA", 24),
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("SC", 31),
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("SD", 18),
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("SE", 24),
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("SI", 19),
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("SK", 24),
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("SM", 27),
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("SO", 23),
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("ST", 25),
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("SV", 28),
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("TL", 23),
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("TN", 24),
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("TR", 26),
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("UA", 29),
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("VA", 22),
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("VG", 24),
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("XK", 20),
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("YE", 30),
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];
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/// The IBAN length for a country code, if the country uses IBANs.
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pub fn iban_length(country: &str) -> Option<usize> {
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IBAN_LENGTHS
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.iter()
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.find(|(code, _)| *code == country)
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.map(|(_, len)| *len)
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}
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/// ISO 13616 / ISO 7064 MOD 97-10 over an IBAN with no spaces, upper case:
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/// move the first four characters to the end, turn letters into 10–35, and
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/// the number mod 97 must be 1. Also checks the country's length.
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pub fn iban(iban: &str) -> bool {
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if iban.len() < 5
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|| !iban
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.bytes()
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.all(|b| b.is_ascii_uppercase() || b.is_ascii_digit())
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{
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return false;
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}
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if iban_length(&iban[..2]) != Some(iban.len())
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|| !iban[2..4].bytes().all(|b| b.is_ascii_digit())
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{
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return false;
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}
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let mut remainder: u32 = 0;
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for b in iban[4..].bytes().chain(iban[..4].bytes()) {
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let value = if b.is_ascii_digit() {
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u32::from(b - b'0')
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} else {
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u32::from(b - b'A') + 10
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};
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remainder = if value >= 10 {
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(remainder * 100 + value) % 97
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} else {
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(remainder * 10 + value) % 97
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};
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}
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remainder == 1
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}
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/// ISO 3166-1 alpha-2 country codes, for SWIFT/BIC positions 5–6.
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const COUNTRIES: &str = "AD AE AF AG AI AL AM AO AQ AR AS AT AU AW AX AZ BA BB BD BE BF BG BH BI BJ \
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BL BM BN BO BQ BR BS BT BV BW BY BZ CA CC CD CF CG CH CI CK CL CM CN CO CR CU CV CW CX CY CZ DE DJ \
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DK DM DO DZ EC EE EG EH ER ES ET FI FJ FK FM FO FR GA GB GD GE GF GG GH GI GL GM GN GP GQ GR GS GT \
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GU GW GY HK HM HN HR HT HU ID IE IL IM IN IO IQ IR IS IT JE JM JO JP KE KG KH KI KM KN KP KR KW KY \
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KZ LA LB LC LI LK LR LS LT LU LV LY MA MC MD ME MF MG MH MK ML MM MN MO MP MQ MR MS MT MU MV MW MX \
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MY MZ NA NC NE NF NG NI NL NO NP NR NU NZ OM PA PE PF PG PH PK PL PM PN PR PS PT PW PY QA RE RO RS \
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RU RW SA SB SC SD SE SG SH SI SJ SK SL SM SN SO SR SS ST SV SX SY SZ TC TD TF TG TH TJ TK TL TM TN \
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TO TR TT TV TW TZ UA UG UM US UY UZ VA VC VE VG VI VN VU WF WS XK YE YT ZA ZM ZW";
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pub fn is_country(code: &str) -> bool {
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code.len() == 2 && COUNTRIES.split(' ').any(|c| c == code)
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn luhn_known_numbers() {
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// Published test card numbers
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for good in [
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"4242424242424242",
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"5555555555554444",
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"378282246310005",
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"79927398713",
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] {
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assert!(luhn(good), "{good}");
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}
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for bad in ["4242424242424241", "79927398710", "1", "12a4"] {
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assert!(!luhn(bad), "{bad}");
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}
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}
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#[test]
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fn iban_registry_examples() {
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// The IBAN registry's own examples
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for good in [
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"GB29NWBK60161331926819",
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"DE89370400440532013000",
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"FR1420041010050500013M02606",
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"NL91ABNA0417164300",
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"BE68539007547034",
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"NO9386011117947",
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"CH9300762011623852957",
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] {
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assert!(iban(good), "{good}");
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}
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for bad in [
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"GB29NWBK60161331926818", // check fails
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"GB29NWBK6016133192681", // too short for GB
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"ZZ29NWBK60161331926819", // no such country
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"DE8937040044053201300A", // letters where DE has none still fail mod 97
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] {
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assert!(!iban(bad), "{bad}");
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}
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}
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#[test]
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fn countries() {
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assert!(is_country("DE") && is_country("US") && is_country("XK"));
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assert!(!is_country("ZZ") && !is_country("D"));
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}
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}
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