v2.0.1 - TCP Race Condition Fix

🐛 Bug Fixes

This release fixes a critical race condition in TCP connection handling that caused use of closed network connection errors in production environments, particularly with HTTP/2.0 queries.

What was fixed?

TCP Race Condition (#1)

• Fixed race condition where TCP connections were closed while query processing goroutines were still running
• Added sync.WaitGroup synchronization to ensure all in-flight queries complete before connection closure
• Prevents "write tcp: use of closed network connection" errors seen in production logs

Technical Details

The issue occurred when:

1. Client sent a DNS query over TCP
2. Query processing started asynchronously in a goroutine
3. Client disconnected or connection timed out
4. Connection was closed immediately
5. Goroutine tried to write response to closed connection → error

The fix ensures graceful shutdown by waiting for all query processing to complete before closing the connection.

Testing

• Added comprehensive TCP connection tests (proxy/tcp_test.go)
• All tests pass with race detector enabled (-race)
• Verified fix prevents connection errors under concurrent load

📦 Installation

Linux (arm64)

wget https://github.com/mojo333/nextdns/releases/download/v2.0.1/nextdns_2.0.1_linux_arm64.tar.gz
tar xzf nextdns_2.0.1_linux_arm64.tar.gz
sudo mv nextdns /usr/bin/

Other Platforms

Download the appropriate archive for your platform from the assets below.

🔍 Checksums

See SHA256SUMS in the release assets for file integrity verification.

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Full Changelog: v2.0.0...v2.0.1