p2p: use header time for compact block recency #36055

pull xternet wants to merge 1 commits into bitcoin:master from xternet:cmpctblock-header-recency changing 2 files +26 −9

xternet commented at 7:50 PM on August 21, 2026: none
Summary
- use the announced block header's timestamp to check unsolicited compact-block recency
- preserve the existing 20-target-spacing cutoff
- leave CanDirectFetch() and its other callers unchanged
- add regression coverage for compact-block relay when the active tip is stale
CanDirectFetch() checks the active tip's timestamp. After 20 target spacings without a block, this causes a recent unsolicited compact block from a high-bandwidth peer to be ignored.

This change uses the announced block header's timestamp for that local check instead. Although header timestamps are miner-selected, this only affects whether reconstruction is attempted; existing proof-of-work, chain-work, peer, resource, and block-validation checks still apply.

Fixes #33578

Test coverage

The functional test keeps the active tip stale and verifies that:
- an old unsolicited compact block is ignored
- a distinct compact block with a recent header triggers GETBLOCKTXN
- mock time is restored after the test
Validation

test/functional/p2p_compactblocks.py
DrahtBot added the label P2P on Aug 21, 2026
DrahtBot commented at 7:50 PM on August 21, 2026: 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/36055.



Reviews

See the guideline and AI policy for information on the review process. A summary of reviews will appear here.
p2p: use header time for compact block recency ce51893c5c
xternet force-pushed on Aug 22, 2026
xternet marked this as ready for review on Aug 22, 2026

in src/net_processing.cpp:4895 in ce51893c5c

4890 | @@ -4891,8 +4891,8 @@ void PeerManagerImpl::ProcessMessage(Peer& peer, CNode& pfrom, const std::string
4891 |              return;
4892 |          }
4893 |  
4894 | -        // If we're not close to tip yet, give up and let parallel block fetch work its magic
4895 | -        if (!already_in_flight && !CanDirectFetch()) {
4896 | +        // If this is not a recent block, give up and let parallel block fetch work its magic
4897 | +        if (!already_in_flight && pindex->Time() <= NodeClock::now() - m_chainparams.GetConsensus().PowTargetSpacing() * 20) {

vicjuma commented at 8:53 PM on August 23, 2026:

Is this even necessary? The essence is to avoid depending on inbound data. Using the already validated time is crucial.

Contributors

Labels

Linked (view graph)

#33578 CanDirectFetch degrades HB compact block relay if blocks are rare

p2p: use header time for compact block recency #36055

Summary

Test coverage

Validation

Code Coverage & Benchmarks

Reviews