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//! # Tau Engine //! //! This crate provides a library that tags documents by running and matching rules over them. //! The engine makes use of a Pratt parser and a tree solver in order to evaluate the detection //! logic of a rule against a document, if the outcome is true the document is considered tagged by //! that rule. //! //! //! ## Rules //! //! A rule is used to tag a document and is made up of three parts: //! - `detection`: the logic used to evaluate a document. //! - `true positive`: an example document that must evaluate to true for the given detection. //! - `true negative`: an example document that must evaluate to false for the given detection. //! //! The detection block is made up of a condition, and identifiers. This allows for simple but //! expressive rules, below is a brief summary (see [Rules](Rule) for more): //! //! ### Identifiers //! //! Identifiers are used to help keep the condition concise and generally contain the core of the //! matching logic. They consist of Key/Value pairs which allow for the extraction of data from the //! document and the evaluate of its value. It should be noted that mappings are treated as //! conjunctions, while sequences are treated as disjunctions. //! //! Identifiers make use of the following matching logic: //! - `foobar`: an exact match of foobar //! - `foobar*`: starts with foobar //! - `*foobar`: ends with foobar //! - `*foobar*`: contains foobar //! - `?foobar`: regex foobar //! //! Any of the above can be made case insensitive with the `i` prefix, for example: //! - `ifoobar` //! - `ifoobar*` //! //! Escaping can be achieved with a combination of `'` and `"`. //! //! ### Condition //! //! The condition is just a boolean expression and supports the following: //! - `and`: logical conjunction //! - `or`: logical disjunction //! - `==`: equality comparison //! - `>`, `>=`, `<`, `<=`: numeric comparisons //! - `not`: negate //! - `all(i)`: make sequences behave as conjunctions //! - `of(i, x)`: ensure a sequence has a minimum number of matches //! //! //! ### Examples //! //! ```text //! detection: //! A: //! foo.bar: foobar //! //! condition: A //! //! true_positives: //! - foo: //! bar: foobar //! //! true_negatives: //! - foo: //! bar: foo //! ``` //! //! ## Documents //! //! A document is anything that can provide data to the engine in a meaningful way, usually through Key/Value //! pairs, i.e: an event log, json object, yaml file, etc. Implementations are achieved with the //! [`Document`](Document) trait. //! //! ## Solving //! //! This is an example of how you can tag a document against a provided rule: //! //! ``` //! use std::borrow::Cow; //! //! use tau_engine::{Document, Rule, Value}; //! //! // Define a document. //! struct Foo { //! foo: String, //! } //! impl Document for Foo { //! fn find(&self, key: &str) -> Option<Value<'_>> { //! match key { //! "foo" => Some(Value::String(Cow::Borrowed(&self.foo))), //! _ => None, //! } //! } //! } //! //! // Write a rule. //! let rule = r#" //! detection: //! A: //! foo: foobar //! condition: A //! true_positives: //! - foo: foobar //! true_negatives: //! - foo: foo //! "#; //! //! // Load and validate a rule. //! let rule = Rule::load(rule).unwrap(); //! assert_eq!(rule.validate().unwrap(), true); //! //! // Create a document. //! let foo = Foo { //! foo: "foobar".to_owned(), //! }; //! //! // Evalute the document with the rule. //! assert_eq!(rule.matches(&foo), true); //! ``` //! //! ## Features //! //! The following are a list of features that can be enabled or disabled: //! - **ignore_case**: Force the engine to always be case insensitive, this will ignore //! the `i` prefix and for that reason is not compatible with case sensitive rules. //! - **json**: Enable serde json support, this will allow the tau-engine to solve on //! `serde_json::Value`. //! //! //! ### JSON //! //! When JSON support is enabled for the tau-engine, the result is a solver that can now reason over //! any document that can be deserialized into `serde_json::Value`. //! //! ```ignore //! # use serde_json::json; //! use tau_engine::{Document, Rule}; //! //! // Write a rule. //! let rule = r#" //! detection: //! A: //! foo: foobar //! condition: A //! true_positives: //! - foo: foobar //! true_negatives: //! - foo: foo //! "#; //! //! // Load and validate a rule. //! let rule = Rule::load(rule).unwrap(); //! assert_eq!(rule.validate().unwrap(), true); //! //! // Create a document. //! let foo = json!({ //! "foo": "foobar", //! }); //! //! // Evalute the document with the rule. //! assert_eq!(rule.matches(&foo), true); //! ``` #![cfg_attr(feature = "benchmarks", feature(test))] #[cfg_attr(test, macro_use)] #[cfg(feature = "benchmarks")] extern crate test; pub use self::document::Document; pub use self::error::{Error, Kind as ErrorKind}; pub use self::rule::Rule; pub use self::solver::solve; pub use self::value::{Array, AsValue, Object, Value}; pub(crate) use error::Result; mod document; mod error; mod identifier; #[cfg(feature = "json")] mod json; mod parser; mod rule; mod solver; mod tokeniser; mod value; mod yaml;