DNS Forwarding Server

A DNS forwarding server written in Go that parses DNS packets, handles name compression, and forwards queries to upstream resolvers.

Features

• Parse DNS messages (header, question, answer sections)
• Handle DNS name compression
• Forward single and multiple DNS queries to upstream resolvers
• Merge responses from multiple queries
• Support A record queries

Architecture

app/
  main.go          # UDP server and CLI
message/
  message.go       # DNS message parsing and forwarding
header/
  header.go        # DNS header parsing
question/
  question.go      # Question section parsing
answer/
  answer.go        # Answer section parsing

Usage

Run the server with a resolver:

./your_program.sh --resolver 8.8.8.8:53

The server listens on port 2053 and forwards DNS queries to the specified resolver.

Implementation Details

• Compression Support: Handles DNS name compression via pointers (2-byte offsets)
• Query Splitting: Automatically splits multi-question queries when necessary
• Response Merging: Combines responses from split queries
• Flag Preservation: Maintains original OPCODE, RD, and transaction ID values