This makes the stalling detection mechanism (previously a fixed
timeout of 2s) adaptive:
If we disconnect a peer for stalling, double the timeout for the
next peer - and let it slowly relax back to its default
value each time the tip advances. (Idea by Pieter Wuille)
This makes situations more unlikely in which we'd keep on
disconnecting many of our peers for stalling, even though our
own bandwidth is insufficient to download a block in 2 seconds.
Co-authored-by: Vasil Dimov <vd@FreeBSD.org>
7ad15d1100 [net processing] Handle IsContinuationOfLowWorkHeadersSync return value correctly when new headers sync is started (dergoegge)
Pull request description:
This PR fixes a bug in the headers sync logic that enables submitting headers to a nodes block index that don't lead to a chain that surpasses our DoS limit.
The issue is that we ignore the return value on [the first `IsContinuationOfLowWorkHeadersSync` call after a new headers sync is started](fabc031048/src/net_processing.cpp (L2553-L2568)), which leads to us passing headers to [`ProcessNewBlockHeaders`](fabc031048/src/net_processing.cpp (L2856)) when that initial `IsContinuationOfLowWorkHeadersSync` call returns `false`. One easy way (maybe the only?) to trigger this is by sending 2000 headers where the last header has a different `nBits` value than the prior headers (which fails the pre-sync logic [here](fabc031048/src/headerssync.cpp (L189))). Those 2000 headers will be passed to `ProcessNewBlockHeaders`.
I haven't included a test here so far because we can't test this without changing the default value for `CRegTestParams::consensus.fPowAllowMinDifficultyBlocks` or doing some more involved refactoring.
ACKs for top commit:
sipa:
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glozow:
ACK 7ad15d1100
Tree-SHA512: 9aabb8bf3700401e79863d0accda0befd2a83c4d469a53f97d827e51139e2f826aee08cdfbc8866b311b153f61fdac9b7aa515fcfa2a21c5e2812c2bf3c03664
It is never a nullptr, otherwise an assertion would fire in
UpdatePeerStateForReceivedHeaders.
Passing a reference makes the code easier to read and less brittle.
dddd1acf58 net: Set relay in version msg to peers with relay permission (MacroFake)
Pull request description:
Seems odd to set the `relay` permission in -blocksonly mode and also ask the peer not to relay transactions.
ACKs for top commit:
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naumenkogs:
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mzumsande:
ACK dddd1acf58
Tree-SHA512: 7bb0e964993ea4982747ae2801fe963ff88586e2ded03015b60ab83172b5b61f2d50e9cde9d7711b7ab207f8639467ecafc4d011ea151ec6c82c722f510f4df7
This changes the minimum chain work for the bitcoin-chainstate
executable. Previously it was uint256{}, now it is the chain's default
minimum chain work.
We optimistically pre-register a peer for txreconciliations
upon sending txreconciliation support announcement.
But if, at VERACK, we realize that the peer never sent
WTXIDRELAY message, we should unregister the peer
from txreconciliations, because txreconciliations rely on wtxids.
Once we received a reconciliation announcement support
message from a peer and it doesn't violate our protocol,
we store the negotiated parameters which will be used
for future reconciliations.
If we're connecting to the peer which might support
transaction reconciliation, we announce we want to reconcile
with them.
We store the reconciliation salt so that when the peer
responds with their salt, we are able to compute the
full reconciliation salt.
This behavior is enabled with a CLI flag.
a3789c700b Improve getpeerinfo pingtime, minping, and pingwait help docs (Jon Atack)
df660ddb1c Update getpeerinfo/-netinfo/TxRelay#m_relay_txs relaytxes docs (for v24 backport) (Jon Atack)
1f448542e7 Always return getpeerinfo "minfeefilter" field (for v24 backport) (Jon Atack)
9cd6682545 Make getpeerinfo field order consistent with its help (for v24 backport) (Jon Atack)
Pull request description:
Various updates and fixups, mostly targeting v24. Please refer to the commit messages for details.
ACKs for top commit:
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vasild:
ACK a3789c700b
Tree-SHA512: b8586a9b83c1b18786b5ac1fc1dba91573c13225fc2cfc8d078f4220967c95056354f6be13327f33b4fcf3e9d5310fa4e1bdc93102cbd6574f956698993a54bf
Previously vExtraTxnForCompact and vExtraTxnForCompactIt were protected
by g_cs_orphans; protect them by g_msgproc_mutex instead, as they
are only used during message processing.
Previously, we would prepare to self-announce to a new peer while
parsing a VERSION message from that peer. This is redundant, because we
do something very similar in MaybeSendAddr(), which is called from
SendMessages() after the version handshake is finished.
There are a couple of differences:
1) MaybeSendAddr() self-advertises to all peers we do address relay with,
not just outbound ones.
2) GetLocalAddrForPeer() called from MaybeSendAddr() makes a
probabilistic decision to either advertise
what they think we are or what we think we are, while
PushAddress(self) on VERSION deterministically only does
the former if the address from the latter is unroutable.
3) During VERSION processing, we haven't received a potential sendaddrv2 message
from our peer yet, so self-advertisements with addresses from addrV2-only networks
would always be dropped in PushAddress().
Since it's confusing to have two slightly different mechanisms for self-advertising,
and the one in MaybeSendAddr() is better, remove the one in VERSION.
Co-authored-by: Martin Zumsande <mzumsande@gmail.com>
Follow-up to #25717. The commit "Utilize anti-DoS headers download
strategy" changed how this bool variable is computed, so that its value
is now the opposite of what it should be.
to the current p2p behavior. We only initialize the Peer::TxRelay m_relay_txs
data structure if it isn't an outbound block-relay-only connection and fRelay=true
(the peer wishes to receive tx announcements) or we're offering NODE_BLOOM to this peer.
There are many cases where we assume message processing is
single-threaded in order for how we access node-related memory to be
safe. Add an explicit mutex that we can use to document this, which allows
the compiler to catch any cases where we try to access that memory from
other threads and break that assumption.
This is an anti-fingerprinting measure. See BlockRequestAllowed in net_processing.
It has been around since 2014, but alternative clients might still serve these blocks.
See also: d8b4b49667, 85da07a5a0, a2be3b66b5, 3788a8479b
3add234546 ui: show header pre-synchronization progress (Pieter Wuille)
738421c50f Emit NotifyHeaderTip signals for pre-synchronization progress (Pieter Wuille)
376086fc5a Make validation interface capable of signalling header presync (Pieter Wuille)
93eae27031 Test large reorgs with headerssync logic (Suhas Daftuar)
355547334f Track headers presync progress and log it (Pieter Wuille)
03712dddfb Expose HeadersSyncState::m_current_height in getpeerinfo() (Suhas Daftuar)
150a5486db Test headers sync using minchainwork threshold (Suhas Daftuar)
0b6aa826b5 Add unit test for HeadersSyncState (Suhas Daftuar)
83c6a0c524 Reduce spurious messages during headers sync (Suhas Daftuar)
ed6cddd98e Require callers of AcceptBlockHeader() to perform anti-dos checks (Suhas Daftuar)
551a8d957c Utilize anti-DoS headers download strategy (Suhas Daftuar)
ed470940cd Add functions to construct locators without CChain (Pieter Wuille)
84852bb6bb Add bitdeque, an std::deque<bool> analogue that does bit packing. (Pieter Wuille)
1d4cfa4272 Add function to validate difficulty changes (Suhas Daftuar)
Pull request description:
New nodes starting up for the first time lack protection against DoS from low-difficulty headers. While checkpoints serve as our protection against headers that fork from the main chain below the known checkpointed values, this protection only applies to nodes that have been able to download the honest chain to the checkpointed heights.
We can protect all nodes from DoS from low-difficulty headers by adopting a different strategy: before we commit to storing a header in permanent storage, first verify that the header is part of a chain that has sufficiently high work (either `nMinimumChainWork`, or something comparable to our tip). This means that we will download headers from a given peer twice: once to verify the work on the chain, and a second time when permanently storing the headers.
The p2p protocol doesn't provide an easy way for us to ensure that we receive the same headers during the second download of peer's headers chain. To ensure that a peer doesn't (say) give us the main chain in phase 1 to trick us into permanently storing an alternate, low-work chain in phase 2, we store commitments to the headers during our first download, which we validate in the second download.
Some parameters must be chosen for commitment size/frequency in phase 1, and validation of commitments in phase 2. In this PR, those parameters are chosen to both (a) minimize the per-peer memory usage that an attacker could utilize, and (b) bound the expected amount of permanent memory that an attacker could get us to use to be well-below the memory growth that we'd get from the honest chain (where we expect 1 new block header every 10 minutes).
After this PR, we should be able to remove checkpoints from our code, which is a nice philosophical change for us to make as well, as there has been confusion over the years about the role checkpoints play in Bitcoin's consensus algorithm.
Thanks to Pieter Wuille for collaborating on this design.
ACKs for top commit:
Sjors:
re-tACK 3add234546
mzumsande:
re-ACK 3add234546
sipa:
re-ACK 3add234546
glozow:
ACK 3add234546
Tree-SHA512: e7789d65f62f72141b8899eb4a2fb3d0621278394d2d7adaa004675250118f89a4e4cb42777fe56649d744ec445ad95141e10f6def65f0a58b7b35b2e654a875
Delay sending SENDHEADERS (BIP 130) message until we know our peer's best
header's chain has more than nMinimumChainWork. This reduces inadvertent
headers messages received during initial headers sync due to block
announcements, which throw off our sync algorithm.
In order to prevent memory DoS, we must ensure that we don't accept a new
header into memory until we've performed anti-DoS checks, such as verifying
that the header is part of a sufficiently high work chain. This commit adds a
new argument to AcceptBlockHeader() so that we can ensure that all call-sites
which might cause a new header to be accepted into memory have to grapple with
the question of whether the header is safe to accept, or needs further
validation.
This patch also fixes two places where low-difficulty-headers could have been
processed without such validation (processing an unrequested block from the
network, and processing a compact block).
Credit to Niklas Gögge for noticing this issue, and thanks to Sjors Provoost
for test code.
Avoid permanently storing headers from a peer, unless the headers are part of a
chain with sufficiently high work. This prevents memory attacks using low-work
headers.
Designed and co-authored with Pieter Wuille.
This introduces an insignificant performance penalty, as it means locator
construction needs to use the skiplist-based CBlockIndex::GetAncestor()
function instead of the lookup-based CChain, but avoids the need for
callers to have access to a relevant CChain object.
eeee5ada23 Make adjusted time type safe (MacroFake)
fa3be799fe Add time helpers (MacroFake)
Pull request description:
This makes follow-ups easier to review. Also, it makes sense by itself.
ACKs for top commit:
ryanofsky:
Code review ACK eeee5ada23. Confirmed type changes and equivalent code changes only.
Tree-SHA512: 51bf1ae5428552177286113babdd49e82459d6c710a07b6e80a0a045d373cf51045ee010461aba98e0151d8d71b9b3b5f8f73e302d46ba4558e0b55201f99e9f
This is a refactor, putting the burden to think about thread safety to
the caller. Otherwise, there is a risk that the caller will assume
thread safety where none exists, as is evident in the previous two
commits.
f6a916683d Add functional test for block announcements during initial headers sync (Suhas Daftuar)
05f7f31598 Reduce bandwidth during initial headers sync when a block is found (Suhas Daftuar)
Pull request description:
On startup, if our headers chain is more than a day behind current time, we'll pick one peer to sync headers with until our best headers chain is caught up (at that point, we'll try to sync headers with all peers).
However, if an INV for a block is received before our headers chain is caught up, we'll then start to sync headers from each peer announcing the block. This can result in doing a big headers sync with many (if not all) of our peers simultaneously, which wastes bandwidth.
This PR would reduce that overhead by picking (at most) one new peer to try syncing headers with whenever a new block is announced, prior to our headers chain being caught up.
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ajtowns:
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mzumsande:
ACK f6a916683d
dergoegge:
Code review ACK f6a916683d
achow101:
ACK f6a916683d
Tree-SHA512: 0662000bd68db146f55981de4adc2e2b07cbfda222b1176569d61c22055e5556752ffd648426f69687ed1cc203105515e7304c12b915d6270df8e41a4a0e1eaa
If our headers chain is behind on startup, then if a block is found we'll try
to catch up from all peers announcing the block, in addition to our initial
headers-sync peer. This commit changes behavior so that in this situation,
we'll choose at most one peer announcing a block to additionally sync headers
from.
fadd8b2676 addrman: Use system time instead of adjusted network time (MarcoFalke)
Pull request description:
This changes addrman to use system time for address relay instead of the network adjusted time.
This is an improvement, because network time has multiple issues:
* It is non-monotonic, even if the system time is monotonic.
* It may be wrong, even if the system time is correct.
* It may be wrong, if the system time is wrong. For example, when the node has limited number of connections (`4`), or the system time is wrong by too much (more than +-70 minutes), or the system time only got wrong after timedata collected more than half of the entries while the time was correct, ...)
This may slightly degrade addr relay for nodes where timedata successfully adjusted the time. Addr relay can already deal with minor offsets of up to 10 minutes. Offsets larger than this should still allow addr relay and not result in a DoS.
ACKs for top commit:
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Code review ACK fadd8b2676
Tree-SHA512: b6c178fa01161544e5bc76c4cb23e11bcc30391f7b7a64accce864923766647bcfce2e8ae21d36fb1ffc1afa07bc46415aca612405bd8d4cc1f319c92a08498f
b4b657ba57 refactor: log `nEvicted` message in `LimitOrphans` then return void (chinggg)
Pull request description:
Fix https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=49347
LimitOrphans() can log expired tx and it should log evicted tx as well instead of returning the `nEvicted` number for caller to print the message.
Since `LimitOrphans()` now returns void, the redundant assertion check in fuzz test is also removed.
Top commit has no ACKs.
Tree-SHA512: 18c41702321b0e59812590cd389f3163831d431f4ebdc3b3e1e0698496a6bdbac52288f28f779237a58813c6717da1a35e8933d509822978ff726c1b13cfc778
`LimitOrphans()` can log expired tx and it should log evicted tx as well
instead of returning the number for caller to print the message.
Since `LimitOrphans()` now return void, the redundant assertion check in
fuzz test is also removed.
8d8eeb422e [net processing] Remove CNode::nLocalServices (John Newbery)
5961f8eea1 [net] Return CService from GetLocalAddrForPeer and GetLocalAddress (dergoegge)
d9079fe18d [net processing] Remove CNode::nServices (John Newbery)
7d1c036934 [net processing] Replace fHaveWitness with CanServeWitnesses() (John Newbery)
f65e83d51b [net processing] Remove fClient and m_limited_node (John Newbery)
fc5eb528f7 [tests] Connect peer in outbound_slow_chain_eviction by sending p2p messages (John Newbery)
1f52c47d5c [net processing] Add m_our_services and m_their_services to Peer (John Newbery)
Pull request description:
Another step in #19398. Which services we offer to a peer and which services they offer to us is application layer data and should not be stored on `CNode`.
This is also a prerequisite for adding `PeerManager` unit tests (See #25515).
ACKs for top commit:
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jnewbery:
utACK 8d8eeb422e
mzumsande:
Code Review ACK 8d8eeb422e
Tree-SHA512: e772eb2a0a85db346dd7b453a41011a12756fc7cbfda6a9ef6daa9633b9a47b9770ab3dc02377690f9d02127301c3905ff22905977f758bf90b17a9a35b37523
