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Prevents panic when unknown messages arrive before destination is initialized. Additional issue found after first fix deployment: when miners send unexpected protocol messages (e.g. eth_submitLogin from Ethereum miners) before the destination connection is established, the code attempted to forward the message to p.proxy.dest.Write() which was nil, causing panic at conn_dest.go:139. This fix adds defensive nil checks in both the MiningExtranonceSubscribe case and the default case before attempting to write to dest. Messages arriving before dest initialization are now safely dropped. Resolves second crash pattern discovered at 2026-02-10 20:56 UTC. Co-authored-by: Cursor <cursoragent@cursor.com>
## Summary Fixes secondary crash discovered after PR #83 deployment. Adds defensive nil checks before attempting to write to destination during handshake phase. ## Root Cause After deploying PR #83 (which fixed the logging crash), a second nil pointer issue was discovered at 2026-02-10 20:56 UTC: When miners send unexpected protocol messages before the destination connection is initialized (e.g., `eth_submitLogin` from Ethereum miners connecting to Bitcoin proxy), the code attempts to forward the message via `p.proxy.dest.Write()`. However, `p.proxy.dest` is nil during early handshake, causing panic at `conn_dest.go:139` via `handler_first_connect.go:83`. ## Changes Made Added defensive nil checks in `handler_first_connect.go` before writing to dest: 1. **MiningExtranonceSubscribe case:** - Check if `p.proxy.dest != nil` before forwarding - Return nil, nil if dest not ready (safe drop) 2. **Default case (unknown messages):** - Check if `p.proxy.dest != nil` before forwarding - Return nil, nil if dest not ready (safe drop) - Updated comment to clarify behavior ## Impact - ✅ Resolves secondary crash pattern at conn_dest.go:139 - ✅ Handles protocol mismatches gracefully (e.g., Ethereum miners on Bitcoin proxy) - ✅ Complements PR #83 to fully stabilize handshake phase - ✅ No performance impact (just pointer checks) ## Evidence **Crash pattern:** ``` panic: runtime error: invalid memory address or nil pointer dereference [signal SIGSEGV: segmentation violation code=0x1 addr=0x110 pc=0x8feae6] at conn_dest.go:139 via handler_first_connect.go:83 ``` **Trigger log (showing PR #83 logging fix working):** ```json {"level":"warn","logger":"PRX","msg":"unknown handshake message from source: {\"id\":2,\"method\":\"eth_submitLogin\"...}", "SrcAddr":"188.166.37.58:47284","DstAddr":"not-initialized","DstPort":"not-connected"} ``` The logging successfully showed "not-initialized" and "not-connected" (PR #83 fix working), but then crashed trying to forward the message. ## Dependencies - Requires PR #83 to be merged first (already done) - This is a follow-up fix discovered during production monitoring Made with [Cursor](https://cursor.com)
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