llm-router/docs

Overview#

The fast_masker plugin provides a simple, rule‑based engine that scans a piece of text and replaces sensitive data ( e‑mail addresses, IPs, URLs, phone numbers, Polish PESEL identifiers, etc.) with clearly marked placeholders.
The core component is the :class:~llm_router_plugins.plugins.fast_masker.core.masker.FastMasker, which receives an ordered list of rule objects and applies each rule sequentially to the input text. Because the rules are applied in the order they are supplied, you can control precedence (e.g., replace URLs before e‑mails if needed).

Masking Rules#

Rule Placeholder What it Detects Notes
EmailRule {{EMAIL}} E‑mail addresses (e.g., user@example.com). Uses a permissive regex that matches the local‑part, @, and a domain with a TLD.
IpRule {{IP}} IPv4, IPv6 addresses and the hostname localhost. Also masks ports as {{IP}}:{{PORT}} when a port follows the address. Light validation of octet ranges; port is captured separately.
UrlRule {{URL}} HTTP/HTTPS URLs and plain domain names (e.g., https://example.com, www.wp.pl). Optional scheme, optional path/query/fragment.
PhoneRule {{PHONE}} Various phone number formats, with optional country/area codes and separators (+48 123 456 789, 123-456-789, (123) 456 7890, 1234567890). Very permissive pattern.
PeselRule {{PESEL}} Polish PESEL numbers (11‑digit personal identifiers). Validates checksum via is_valid_pesel.
BankAccountRule {{BANK_ACCOUNT}} Polish IBAN numbers (full 28‑character form) and partially masked accounts where any group may contain X. Matches exact length; no further validation required.
DateNumberRule {{DATE_NUM}} Numeric dates in forms YYYY.MM.DD, DD.MM.YYYY (also with -, / or whitespace separators). Handles surrounding whitespace; replaces with {{DATE_NUM}}.
DateWordRule {{DATE_STR}} Textual dates in Polish and English (e.g., 12 stycznia 2023, January 12, 2023). Supports month names, abbreviations, optional ordinal suffixes and commas.
KrsRule {{KRS}} Polish KRS numbers (plain or hyphen‑separated) that pass checksum validation. Uses is_valid_krs for verification.
MoneyRule {{MONEY}} Monetary amounts that contain a currency identifier (symbols, ISO codes, or Polish words) together with a number. Discards surrounding markdown emphasis; replaces whole match.
NipRule {{NIP}} Polish NIP numbers (plain, hyphen‑separated, embedded in letters, or wrapped in markdown). Validates checksum via _is_valid_nip.
PostalCodeRule {{POSTAL_CODE}} Polish postal codes in forms dd-ddd or ddddd, optionally wrapped in markdown emphasis. No checksum validation; format‑based detection only.
RegonRule {{REGON}} Polish REGON numbers (9 or 14 digits, optionally split by single spaces) that pass checksum validation. Uses is_valid_regon after stripping spaces.
StreetNameRule (beta) {{STREET}} Polish street names with optional house numbers (e.g., ul. Mickiewicza 12, aleja Jana Pawła II). Recognises common street type prefixes and abbreviations; case‑insensitive, diacritics supported.
SimplePersonalDataRule (beta) {{MASKED}} Polish surnames loaded from CSV resources; matches whole words that start with an uppercase letter. Uses a pre‑loaded set of surnames with heuristic inflection handling.
BaseRule (abstract) — Provides common behaviour for rules that only need a compiled regular expression and a placeholder. Concrete rules inherit from this class.

Each rule implements the :class:~llm_router_plugins.plugins.fast_masker.core.rule_interface.MaskerRuleI interface, exposing an apply(text: str) -> str method that returns the transformed string.

Utility Validators#

The plugin provides a set of helper functions used by several masking rules to verify the correctness of identified identifiers:

  • is_valid_pesel(pesel: str) -> bool – validates Polish PESEL numbers by checking length, date components and checksum.
  • is_valid_krs(krs: str) -> bool – checks the KRS checksum for both plain and hyphen‑separated forms.
  • is_valid_regon(regon: str) -> bool – validates 9‑ or 14‑digit REGON numbers, handling optional spaces and checksum calculation.
  • _is_valid_nip(nip: str) -> bool – internal helper used by NipRule to verify the Polish NIP checksum.
  • Additional internal helpers (e.g., _load_surnames, _generate_inflected_forms) support the beta rules but are not part of the public validator API.

These validators reside in llm_router_plugins/plugins/fast_masker/utils/validators.py and are imported by the corresponding rule implementations. They return True for valid values and False otherwise, allowing the masking rules to replace only genuine identifiers.

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