contrib: tracing: Fix read of pmsg_type in p2p_monitor.py #32771

1. 
   davidgumberg commented at 6:45 pm on June 18, 2025: contributor

   This fixes a bug in the contrib tracing script p2p_monitor.py. currently the script fails to read the msg_type of inbound and outbound messages, which is useful in the per-peer message view.

   

   

2. contrib: tracing: Correctly read msg type in p2p_monitor.py 3473986fe1
3. DrahtBot added the label Scripts and tools on Jun 18, 2025
4. 
   DrahtBot commented at 6:45 pm on June 18, 2025: contributor

   The following sections might be updated with supplementary metadata relevant to reviewers and maintainers.

   Code Coverage & Benchmarks

   For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/32771.

   Reviews

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   Type	Reviewers
   ACK	janb84, 0xB10C, yuvicc

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5. fanquake requested review from 0xB10C on Jun 18, 2025
6. 
   janb84 commented at 7:44 am on June 19, 2025: contributor

   ut ACK 3473986fe10e2689fe36cc93e1e50013649ac14b

   This PR fixes bug not displaying msg_type. bpf_probe_read_user_str(&msg.msg_type, sizeof(msg.msg_type), pmsg_type tries to copy pmsg_type into kernel space but pmsg_type was still NULL (unassigned). This PR changes bpf_usdt_readarg to copy argument 4 to pmsg_type fixing the bug.

   Steps taken in this review:

   • git blame (history of bug) ✅
   • code review ✅
7. 0xB10C approved
8. 
   0xB10C commented at 7:23 am on June 20, 2025: contributor

   ACK 3473986fe10e2689fe36cc93e1e50013649ac14b

   Changes look good to me, but I haven’t tested them yet.

   Introduced by me in https://github.com/bitcoin/bitcoin/commit/ec47ba349d0b3cb2d274593ca7b828ae70584e10

9. 
   yuvicc commented at 8:38 pm on June 20, 2025: contributor

   Concept ACK

   It would be good to have the message type with the size of message in p2p_monitor.py

10. 
    yuvicc commented at 9:03 pm on June 20, 2025: contributor

    ACK 3473986fe10e2689fe36cc93e1e50013649ac14b

    Testing

    On master

    

    commit 3473986fe10e2689fe36cc93e1e50013649ac14b

    

11. fanquake merged this on Jun 23, 2025
12. fanquake closed this on Jun 23, 2025

    ---

13. fanquake referenced this in commit 5697605414 on Jun 23, 2025
14. 
    fanquake commented at 9:03 am on June 23, 2025: member

    Backported to 29.x in #32589.

Contributors
davidgumberg DrahtBot janb84 0xB10C yuvicc fanquake

Labels
Scripts and tools