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Fuzzing Tests for EtchDNS

This directory contains fuzzing tests for the EtchDNS DNS parsers using cargo-fuzz.

Prerequisites

You need to have cargo-fuzz installed:

cargo install cargo-fuzz

Available Fuzz Targets

The following fuzz targets are available:

  1. validate_dns_packet - Tests the dns_parser::validate_dns_packet function
  2. qname - Tests the dns_parser::qname function
  3. query_type_class - Tests the dns_parser::query_type_class function
  4. is_dnssec_requested - Tests the dns_parser::is_dnssec_requested function
  5. extract_edns_version - Tests the dns_parser::extract_edns_version function
  6. extract_client_ip - Tests EDNS Client Subnet IP extraction
  7. create_dns_response - Tests synthetic DNS response construction
  8. dns_key_from_packet - Tests the DNSKey::from_packet function
  9. ip_range_from_cidr - Tests IpRange::from_cidr CIDR parsing
  10. ip_validator_validate - Tests IpValidator::validate_ip_str
  11. rate_limiter_is_allowed - Tests RateLimiter::is_allowed

Running the Fuzzing Tests

To run a specific fuzz target:

cargo fuzz run validate_dns_packet
cargo fuzz run qname
cargo fuzz run query_type_class
cargo fuzz run is_dnssec_requested
cargo fuzz run extract_edns_version
cargo fuzz run extract_client_ip
cargo fuzz run create_dns_response
cargo fuzz run dns_key_from_packet
cargo fuzz run ip_range_from_cidr
cargo fuzz run ip_validator_validate
cargo fuzz run rate_limiter_is_allowed

Corpus

Each fuzz target has its own corpus directory in fuzz/corpus/<target_name>/. The corpus contains initial valid DNS packets to help the fuzzer find interesting inputs.

The corpus is automatically generated when building the fuzz targets.

Customizing Fuzzing Runs

You can customize the fuzzing run with additional options:

# Run with a time limit (e.g., 60 seconds)
cargo fuzz run validate_dns_packet -- -max_total_time=60

# Run with a specific number of iterations
cargo fuzz run validate_dns_packet -- -runs=1000000

# Run with more detailed output
cargo fuzz run validate_dns_packet -- -v

Handling Crashes

When a fuzzer finds a crash, it will save the input that caused the crash in fuzz/artifacts/<target_name>/. You can reproduce the crash with:

cargo fuzz run <target_name> <path_to_artifact>

Adding New Fuzz Targets

To add a new fuzz target:

  1. Add a new entry to fuzz/Cargo.toml
  2. Create a new file in fuzz/fuzz_targets/
  3. Update the corpus generator in fuzz/generate_corpus.rs if needed