addrman: make `m_last_good` network-specific #35750

pull mzumsande wants to merge 2 commits into bitcoin:master from mzumsande:202607_addrman_last_good changing 3 files +61 −4

mzumsande commented at 9:55 PM on July 19, 2026: contributor

m_last_good is used to prevent recording failed attempts for addresses when it is our connectivity that is at fault. However, it is quite common that only some networks are unreachable - e.g. I have encountered it frequently that IPv6 is unreachable, while IPv4 works fine. In this case it is not correct to increase the failed counter for an IPv6 address and ultimately making it Terrible, just because we are making IPv4 connections.

Fix this by making m_last_good network-specific. Also change the initial value from 1 to 0, so that in a situation when there was no previous attempt for an address, but also no previous successful connection to its network, the failed count is not increased. The intial value was not a major issue previously because we would only count failures after having at least two outbound connections (in which case m_last_good would have been set).

addrman: don't count connection failures before the first success

m_last_good was initialised to 1 instead of 0, so that an entry whose
m_last_count_attempt is still 0 is eligible for one counted failure even
though we have never connected to anything successfully.

In practice, this makes little difference: net.cpp normally only passes
fCountFailure once we have at least two outbound peers, which implies
that Good() has already been called.
However, it is changed here in preparation of making m_last_good a
network-specific array.

b8840fd1c6

DrahtBot added the label P2P on Jul 19, 2026
DrahtBot commented at 9:55 PM on July 19, 2026: contributor



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addrman: make m_last_good network-specific

Attempt_() only counts a failed connection attempt if
we have made a successful connection since the last attempt,
so that we don't blame addresses for our own lack of connectivity.
This was network-agnostic: successful connections on any
network re-enabled the check for all addresses.

As a result, a network that is unreachable for us while others keep
working - e.g. if IPv6 is not reachable, or a non-working Tor proxy -
would lead to addresses of that network becoming Terrible.

Avoid this by tracking the last successful connection per
network instead.

31191b5239

mzumsande force-pushed on Jul 19, 2026
DrahtBot added the label CI failed on Jul 19, 2026
DrahtBot removed the label CI failed on Jul 19, 2026
fjahr commented at 8:29 AM on July 20, 2026: contributor

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addrman: make `m_last_good` network-specific #35750

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