Feat: Enhance DNS support in bootstrap discovery

[yashksaini-coder]

PR: Enhance DNS support in bootstrap discovery

Issue: #1187
Discussion: #1171 (Bootstrap DNS enhancement)

Summary

This PR enhances DNS support in bootstrap discovery by:

1. Extended protocol support: Recognizing dns, dns4, and dns6 in addition to dnsaddr in is_dns_addr(), enabling IPv4/IPv6-specific resolution control and alignment with the libp2p multiaddr specification.
2. Robust error handling: Wrapping DNS resolution in try/except, distinguishing “resolution failed” from “no results,” logging informative messages (address + error/details), and ensuring bootstrap continues processing other addresses after DNS failures.

Motivation

• Limited protocol support: Previously only dnsaddr was treated as a DNS address; dns, dns4, and dns6 were ignored, preventing IPv4/IPv6-specific bootstrap behaviour.
• Minimal error handling: Only None was checked; there was no distinction between resolution failure and empty results, and little diagnostic information for debugging.

Changes

Code

• libp2p/discovery/bootstrap/bootstrap.py
  • is_dns_addr(addr): Now returns True for addresses whose first protocol is one of dns, dns4, dns6, or dnsaddr (set-based check over addr.protocols()).
  • _process_bootstrap_addr(addr_str):
    • Invalid multiaddr format: caught and logged at debug level; return (no raise).
    • DNS addresses: resolver.resolve(multiaddr) wrapped in try/except. On exception: log warning with address and exception; return. On success: if resolved_addrs is falsy (None or empty list), log warning and return. Otherwise use resolved addresses and existing peer_id/add_addr logic.
    • Ensures one failing DNS address does not stop other bootstrap addresses from being processed.

Tests

• tests/core/discovery/bootstrap/test_utils.py
  • test_is_dns_addr_dns_protocols: Asserts that is_dns_addr() returns True for /dns4/..., /dns6/..., /dns/..., /dnsaddr/... and False for /ip4/..., /ip6/....

Behaviour

• Backward compatibility: Existing dnsaddr bootstrap entries behave as before.
• Existing tests: All existing discovery/bootstrap tests continue to pass.

Requirements coverage (from issue)

Req	Description	Status
1	is_dns_addr() recognizes dns, dns4, dns6, dnsaddr	✅
2	Exception handling for DNS resolution	✅ (py-multiaddr does not expose ResolutionError/RecursionLimitError; all failures caught and logged)
3	Distinguish “no results” vs “resolution failed”	✅
4	Informative error messages (address + details)	✅
5	Bootstrap continues after DNS failures	✅
6	Backward compatibility with dnsaddr	✅
7	Unit tests for DNS protocol types	✅ (protocol detection); optional: explicit exception-path test
8	Integration tests with dns4/dns6	✅ (test_integration: DNS addresses in host, DNS failure/empty continues with mocks)
9	Documentation with examples	✅ (Getting Started + libp2p.discovery.bootstrap + newsfragment 1171)
10	All existing tests pass	✅

Testing

• pytest tests/core/discovery/bootstrap/ -v
• Broader discovery/transport test runs as needed for regressions.

Open questions (from issue, out of scope for this PR)

• Retry with exponential backoff for DNS failures
• Metrics/monitoring for DNS resolution success/failure
• Default DNS timeout
• DNS caching

Checklist

• is_dns_addr() updated for dns, dns4, dns6, dnsaddr
• DNS resolution wrapped in try/except with informative logging
• “No results” and “resolution failed” handled separately
• Bootstrap continues with other addresses on DNS failure
• Unit test for DNS protocol detection added
• Existing tests pass
• Integration test with dns4/dns6 (test_bootstrap_integration_with_dns_addresses; test_bootstrap_dns_resolution_failure_continues; test_bootstrap_dns_empty_results_continues)
• User-facing doc with DNS bootstrap examples (Getting Started: Bootstrap address formats; libp2p.discovery.bootstrap: supported types + examples; newsfragment 1171.feature.rst)

[sumanjeet0012]

@yashksaini-coder The current PR and issue focus on enhancing the bootstrap module to support DNS resolution. However, the proposed changes also modify the circuit relay, WebSockets, and several other modules.
To maintain clarity and proper scope management, please either update the issue and PR descriptions to reflect these additional changes or create separate issues for adding DNS resolution support to the other affected modules.

[yashksaini-coder]

@yashksaini-coder The current PR and issue focus on enhancing the bootstrap module to support DNS resolution. However, the proposed changes also modify the circuit relay, WebSockets, and several other modules. To maintain clarity and proper scope management, please either update the issue and PR descriptions to reflect these additional changes or create separate issues for adding DNS resolution support to the other affected modules.

Yes Understood I will update the issue and PR regarding the new changes required