Wirefilter

This is an execution engine for Wireshark®-like filters.

It contains public APIs for parsing filter syntax, compiling them into an executable IR and, finally, executing filters against provided values.

Example

use wirefilter::{ExecutionContext, Scheme};

fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Create a map of possible filter fields.
    let scheme = Scheme! {
        http.method: Bytes,
        http.ua: Bytes,
        port: Int,
    }
    .build();

    // Parse a Wireshark-like expression into an AST.
    let ast = scheme.parse(
        r#"
            http.method != "POST" &&
            not http.ua matches "(googlebot|facebook)" &&
            port in {80 443}
        "#,
    )?;

    println!("Parsed filter representation: {:?}", ast);

    // Compile the AST into an executable filter.
    let filter = ast.compile();

    // Set runtime field values to test the filter against.
    let mut ctx = ExecutionContext::new(&scheme);

    ctx.set_field_value(scheme.get_field("http.method").unwrap(), "GET")?;

    ctx.set_field_value(
        scheme.get_field("http.ua").unwrap(),
        "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:66.0) Gecko/20100101 Firefox/66.0",
    )?;

    ctx.set_field_value(scheme.get_field("port").unwrap(), 443)?;

    // Execute the filter with given runtime values.
    println!("Filter matches: {:?}", filter.execute(&ctx)?); // true

    // Amend one of the runtime values and execute the filter again.
    ctx.set_field_value(scheme.get_field("port").unwrap(), 8080)?;

    println!("Filter matches: {:?}", filter.execute(&ctx)?); // false

    Ok(())
}

Fuzzing

There are fuzz tests in the fuzz directory.

Install afl:

cargo install afl --force

Build bytes fuzz test:

cd fuzz/bytes
cargo afl build

Run fuzz test (from inside fuzz/bytes directory):

cargo afl fuzz -i in -o out ../../target/debug/fuzz-bytes

If you see an error like:

Looks like the target binary is not instrumented!

Try deleting the compiled binary and re-building with cargo afl build.

Licensing

Licensed under the MIT license. See the LICENSE file for details.