feat/606-enable-nat-traversal-via-hole-punching

[Winter-Soren]

What was wrong?

Issue #606 requested the implementation of Direct Connection Upgrade through Relay (DCUtR) protocol in py-libp2p. This protocol enables peers that initially connect through a relay to establish direct connections when possible, improving performance and reducing relay load.

Issue #606

How was it fixed?

I implemented the DCUtR protocol according to the libp2p spec The implementation includes:

1. A DCUtRProtocol class that handles the protocol logic for hole punching
2. NAT detection utilities to determine if peers are publicly reachable
3. Protocol message handling for connection upgrade coordination
4. Integration with the existing relay functionality

The implementation allows peers to exchange observed addresses and synchronize connection attempts to punch through NATs. When successful, peers can upgrade from relayed connections to direct connections, improving performance and reducing load on relay nodes.

To-Do

• Clean up commit history
• Add or update documentation related to these changes
• Add entry to the release notes

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