dns_resolver

A simple, command-line DNS resolver implemented in Rust. This tool allows you to perform DNS queries for various record types against a specified DNS server. It is built from scratch, handling the creation of DNS query packets and the parsing of response packets.

Features

• Query for A, AAAA, MX, and TXT records.
• Specify one or more target domains in a single command.
• Option to use a custom DNS server.
• Asynchronous network operations using Tokio.
• Parses DNS responses, including support for compressed domain names.
• Provides clear, human-readable output for query results.

Prerequisites

• Rust and Cargo must be installed.

Installation & Building

1. Clone the repository:

   git clone https://github.com/venoosoo/dns_resolver.git
   cd dns_resolver

2. Build the project. For a development build:

   cargo build

   For an optimized release build:

   cargo build --release

   The executable will be located at target/debug/dns or target/release/dns.

Usage

You can run the resolver using cargo run or by executing the compiled binary directly.

Command-Line Arguments

• --target <DOMAIN...>: (Required) One or more domain names to query.
• --type <RECORD_TYPE>: The type of DNS record to query for. Defaults to A.
  • Possible values: a, mx, txt, aaaa
• --server <IP_ADDRESS>: The IP address of the DNS server to use. Defaults to 1.1.1.1.

Examples

Query for an A record (default):

cargo run -- --target google.com

Query for AAAA (IPv6) records for multiple domains:

cargo run -- --target google.com github.com --type aaaa

Query for MX (Mail Exchange) records using Google's DNS server:

cargo run -- --target proton.me --type mx --server 8.8.8.8

Example Output:

$ cargo run -- --target google.com --type a
   Compiling dns v0.1.0 (/path/to/dns_resolver)
    Finished dev [unoptimized + debuginfo] target(s) in 0.50s
     Running `target/debug/dns --target google.com --type a`
The results for google.com
Got answer records
A     142.250.180.142   TTL 143

Project Structure

The project is organized into several modules to handle different aspects of the DNS resolution process:

• src/main.rs: The main entry point. Handles command-line argument parsing with clap and orchestrates the query process.
• src/dns_header.rs: Defines the DnsHeader struct and logic for creating and writing the header part of a DNS query packet.
• src/dns_question.rs: Defines the DnsQuestion struct for building the "question" section of a DNS query, including domain name encoding.
• src/dns_packet.rs: A simple container that combines a DnsHeader and DnsQuestion to form a complete query packet.
• src/parse_answer.rs: Contains the logic for parsing the binary response from a DNS server. It handles different record types (A, AAAA, MX), decodes compressed names, and prints the results in a user-friendly format.