net: Quiet down logging when router doesn’t support natpmp/pcp #33311

1. 
   laanwj commented at 7:27 pm on September 4, 2025: member

   When the router doesn’t support natpmp and PCP, one’d normally expect the UDP packet to be ignored, and hit a time out. This logs a message that is already in the debug category. However, there’s also the case in which sending an UDP packet causes a ICMP response (type 3, code 3 “port unreachable”). This is returned to user space as “connection refused” (despite UDP having no concept of connections).

   Move the warnings from Send and Recv to debug level too, to reduce log spam in that case.

   Closes #33301.

2. net: Quiet down logging when router doesn't support natpmp/pcp

   When the router doesn't support natpmp and PCP, one'd normally expect
   the UDP packet to be ignored, and hit a time out. This logs a warning
   that is already in the debug category. However, there's also the case in
   which sending an UDP packet causes a ICMP response. This is returned to
   user space as "connection refused" (despite UDP having no concept of
   connections).
   
   Move the warnings from `Send` and `Recv` to debug level too, to reduce
   log spam in that case.
   
   Closes #33301.

   4f1a4cbccd
3. DrahtBot added the label P2P on Sep 4, 2025
4. 
   DrahtBot commented at 7:27 pm on September 4, 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/33311.

   Reviews

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   Type	Reviewers
   ACK	darosior, willcl-ark, mzumsande, sipa, davidgumberg, achow101

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5. maflcko added this to the milestone 30.0 on Sep 4, 2025
6. darosior approved
7. 
   darosior commented at 7:31 pm on September 4, 2025: member

   utACK 4f1a4cbccd784e25f7932f1d0293602ef7f3e814
8. 
   willcl-ark commented at 7:40 pm on September 4, 2025: member

   utACK 4f1a4cbccd784e25f7932f1d0293602ef7f3e814

   Makes sense to demote this message to Debug level.

9. 
   mzumsande commented at 8:33 pm on September 4, 2025: contributor

   utACK 4f1a4cbccd784e25f7932f1d0293602ef7f3e814
10. 
    sipa commented at 9:07 pm on September 4, 2025: member

    utACK 4f1a4cbccd784e25f7932f1d0293602ef7f3e814
11. 
    davidgumberg commented at 9:07 pm on September 4, 2025: contributor

    Tested ACK https://github.com/bitcoin/bitcoin/commit/4f1a4cbccd784e25f7932f1d0293602ef7f3e814

    Tested on a network where the default gateway does not support NatPMP with -natpmp=1: pcp: Could not receive response: Connection refused on this branch is not printed, on master it is.

    0$ mkdir -p /tmp/datadir && ./build/bin/bitcoind -datadir=/tmp/datadir -regtest -natpmp=1 | grep -i pcp 
    

    On master:

    02025-09-04T21:03:19Z [net:warning] pcp: Could not receive response: Connection refused (111)
    12025-09-04T21:03:19Z [net:warning] pcp: Could not receive response: Connection refused (111)
    

    On this branch there is no output.

12. 
    achow101 commented at 10:16 pm on September 4, 2025: member

    ACK 4f1a4cbccd784e25f7932f1d0293602ef7f3e814
13. achow101 merged this on Sep 4, 2025
14. achow101 closed this on Sep 4, 2025

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Contributors
laanwj DrahtBot darosior willcl-ark mzumsande sipa davidgumberg achow101

Labels
P2P

Milestone
30.0