baDNS

baDNS is a DNS server written in Rust, leveraging the rustdns library for core functionality. It uses QuickJS to evaluate configuration files, allowing for dynamic and programmable DNS handling. When a DNS request is received, baDNS first routes the request to the JavaScript context defined by the configuration. If a response is generated within the JS context, it is returned. Otherwise, baDNS queries the configured upstream servers sequentially and caches the response for the specified TTL.

Features

Programmable DNS Handling: Define custom DNS logic using JavaScript.
Flexible Configuration: Use JavaScript to define how DNS requests are processed.
Upstream Server Support: Automatically query upstream servers if the JS context does not provide a response.
Response Caching: Cache upstream responses based on their TTL.
HTTP Reverse Proxy: Set up HTTP reverse proxy for domains.

Installation

To install baDNS, follow these steps:

Ensure you have Rust installed. If not, download it from rust-lang.org.

Clone the baDNS repository:

git clone https://github.com/asivery/badns.git
cd badns

Build the project using Cargo:
```
cargo build --release
```
The binary will be located in target/release/badns.

Usage

To run baDNS, execute the following command:

./badns <config-file>

Replace <config-file> with the path to your JavaScript configuration file.

Configuration

The configuration file is a JavaScript file evaluated by QuickJS. Below is a summary of the available functions and their purposes:

Main Initialization

The main baDNS initialization file is executed before the configuration file. It prepares the environment and exposes user-friendly methods for DNS handling.

Functions

Network Setup

bindAddress(address: string, port = 53): Binds the UDP address and starts listening. Multiple interfaces can be open simultaneously.
upstream(address: string, port = 53): Adds an upstream server. Queries upstream servers sequentially if no JS context response is found.

HTTP Reverse Proxy

setupHTTPRedirectServer(address: string, port: number, recordTarget: string): Sets up the HTTP reverse proxy server - it needs to know its own IP address, so that it redirects correctly.
addHTTPRedirect(target: string, name: string): Adds a reverse proxy entry to bind the domain name to the HTTP address target.

DNS Bindings

addBinding(rrtype: RRConstant, name: string, handler: Handler): Adds a binding for a specific rrtype and name.
addABinding(name: string, handler: Handler): Adds an RR_A binding.
addAAAABinding(name: string, handler: Handler): Adds an RR_AAAA binding.
addCNAMEBinding(name: string, handler: Handler): Adds an RR_CNAME binding.
addUniversalBinding(handler: Handler): Adds a universal binding triggered on every query unless overridden by specific bindings.

Helper Functions

STUB(): Returns an RR_A response with an infinite TTL pointing to 0.0.0.0.
permanentBinding(ip: string, domain: string): Adds a permanent RR_A binding.
ban(domain: string): Bans a domain using a STUB() handler.
exec(filename: string): Evaluates the contents of the provided file.

baDNS Extensions

sha256(data: string): Generates a SHA256 digest of the provided data.
readFile(filename: string): Reads and returns the contents of the specified file as UTF-8.

Example Configuration

Below is an example configuration file demonstrating basic usage:

// Bind to port 53 on all interfaces
bindAddress('0.0.0.0');

// Set up an upstream DNS server
upstream('8.8.8.8');

// Add a permanent A record binding
permanentBinding('192.168.1.1', 'example.com');

// Ban a specific domain
ban('malicious.com');

// Set up the HTTP reverse proxy server on port 80, with the server returning its own address as 192.168.1.2
setupHTTPRedirectServer('0.0.0.0', 80, '192.168.1.2');

// Add a reverse proxy entry to bind the domain 'web.example.com' to HTTP address 'http://localhost:3000'
addHTTPRedirect('192.168.1.123:3000', 'internal.site');

// Universal binding for all queries
addUniversalBinding((name, rrtype, rrclass, peerAddress, ownAddress) => {
    console.log(`Query received: ${name}, type: ${rrtype}`);
    return { special: true, specialType: 'queryUpstream' };
});

Feel free to reach out with any questions or feedback regarding baDNS. Happy DNS serving!