Add new PeerManagerImpl::TryDownloadingHistoricalBlocks method and use it to
request background chain blocks in addition to blocks normally requested by
FindNextBlocksToDownload.
Co-authored-by: Ryan Ofsky <ryan@ofsky.org>
Co-authored-by: James O'Beirne <james.obeirne@gmail.com>
fa626af3ed Remove unused legacy CHashVerifier (MarcoFalke)
fafa3fc5a6 test: add tests that exercise WithParams() (MarcoFalke)
fac81affb5 Use serialization parameters for CAddress serialization (MarcoFalke)
faec591d64 Support for serialization parameters (MarcoFalke)
fac42e9d35 Rename CSerAction* to Action* (MarcoFalke)
aaaa3fa947 Replace READWRITEAS macro with AsBase wrapping function (MarcoFalke)
Pull request description:
It seems confusing that picking a wrong value for `ADDRV2_FORMAT` could have effects on consensus. (See the docstring of `ADDRV2_FORMAT`).
Fix this by implementing https://github.com/bitcoin/bitcoin/issues/19477#issuecomment-1147421608 .
This may also help with libbitcoinkernel, see https://github.com/bitcoin/bitcoin/pull/28327
ACKs for top commit:
TheCharlatan:
ACK fa626af3ed
ajtowns:
ACK fa626af3ed
Tree-SHA512: 229d379da27308890de212b1fd2b85dac13f3f768413cb56a4b0c2da708f28344d04356ffd75bfcbaa4cabf0b6cc363c4f812a8f1648cff9e436811498278318
This also cleans up the addrman (de)serialization code paths to only
allow `Disk` serialization. Some unit tests previously forced a
`Network` serialization, which does not make sense, because Bitcoin Core
in production will always `Disk` serialize.
This cleanup idea was suggested by Pieter Wuille and implemented by Anthony
Towns.
Co-authored-by: Pieter Wuille <pieter@wuille.net>
Co-authored-by: Anthony Towns <aj@erisian.com.au>
This comment isn't in the right place, as detection of a tx in
recent_rejects would cause the function to exit much earlier.
Move the comment to the right place and tweak the first sentence for
accuracy.
- Whenever a tx is erased. Allows somebody to see which transactions
have been erased due to expiry/overflow, not just how many.
- Whenever a tx is added to a peer's workset.
- AcceptToMemoryPool when a tx is accepted, mirroring the one logged for
a tx received from a peer. This allows someone to see all of the
transactions that are accepted to mempool just by looking for ATMP logs.
- MEMPOOLREJ when a tx is rejected, mirroring the one logged for
a tx received from a peer. This allows someone to see all of the
transaction rejections by looking at MEMPOOLREJ logs.
This change makes IsInitialBlockDownload and NotifyHeaderTip functions no
longer tied to individual Chainstate objects. It makes them work with the
ChainstateManager object instead so code is simpler and it is no longer
possible to call them incorrectly with an inactive Chainstate.
This change also makes m_cached_finished_ibd caching easier to reason about,
because now there is only one cached value instead of two (for background and
snapshot chainstates) so the cached IBD state now no longer gets reset when a
snapshot is loaded.
There should be no change in behavior because these functions were always
called on the active ChainState objects.
These changes were discussed previously
https://github.com/bitcoin/bitcoin/pull/27746#discussion_r1246868905 and
https://github.com/bitcoin/bitcoin/pull/27746#discussion_r1237552792 as
possible followups for that PR.
fb02ba3c5f mempool_entry: improve struct packing (Anthony Towns)
1a118062fb net_processing: Clean up INVENTORY_BROADCAST_MAX constants (Anthony Towns)
6fa49937e4 test: Check tx from disconnected block is immediately requestable (glozow)
e4ffabbffa net_processing: don't add txids to m_tx_inventory_known_filter (Anthony Towns)
6ec1809d33 net_processing: drop m_recently_announced_invs bloom filter (Anthony Towns)
a70beafdb2 validation: when adding txs due to a block reorg, allow immediate relay (Anthony Towns)
1e9684f39f mempool_entry: add mempool entry sequence number (Anthony Towns)
Pull request description:
This PR replaces the `m_recently_announced_invs` bloom filter with a simple sequence number tracking the mempool state when we last considered sending an INV message to a node. This saves 33kB per peer (or more if we raise the rate at which we relay transactions over the network, in which case we would need to increase the size of the bloom filter proportionally).
The philosophy here (compare with #18861 and #19109) is that we consider the rate limiting on INV messages to only be about saving bandwidth and not protecting privacy, and therefore after you receive an INV message, it's immediately fair game to request any transaction that was in the mempool at the time the INV message was sent. We likewise consider the BIP 133 feefilter and BIP 37 bloom filters to be bandwidth optimisations here, and treat transactions as requestable if they would have been announced without those filters. Given that philosophy, tracking the timestamp of the last INV message and comparing that against the mempool entry time allows removal of each of `m_recently_announced_invs`, `m_last_mempool_req` and `UNCONDITIONAL_RELAY_DELAY` and associated logic.
ACKs for top commit:
naumenkogs:
ACK fb02ba3c5f
amitiuttarwar:
review ACK fb02ba3c5f
glozow:
reACK fb02ba3c5f
Tree-SHA512: cbba5ee04c86df26b6057f3654c00a2b45ec94d354f4f157a769cecdaa0b509edaac02b3128afba39b023e82473fc5e28c915a787f84457ffe66638c6ac9c2d4
d8f1222ac5 refactor: Correct dbwrapper key naming (TheCharlatan)
be8f159ac5 build: Remove leveldb from BITCOIN_INCLUDES (TheCharlatan)
c95b37d641 refactor: Move CDBWrapper leveldb members to their own context struct (TheCharlatan)
c534a615e9 refactor: Split dbwrapper CDBWrapper::EstimateSize implementation (TheCharlatan)
586448888b refactor: Move HandleError to dbwrapper implementation (TheCharlatan)
dede0eef7a refactor: Split dbwrapper CDBWrapper::Exists implementation (TheCharlatan)
a5c2eb5748 refactor: Fix logging.h includes (TheCharlatan)
84058e0eed refactor: Split dbwrapper CDBWrapper::Read implementation (TheCharlatan)
e4af2408f2 refactor: Pimpl leveldb::Iterator for CDBIterator (TheCharlatan)
ef941ff128 refactor: Split dbwrapper CDBIterator::GetValue implementation (TheCharlatan)
b7a1ab5cb4 refactor: Split dbwrapper CDBIterator::GetKey implementation (TheCharlatan)
d7437908cd refactor: Split dbwrapper CDBIterator::Seek implementation (TheCharlatan)
ea8135de7e refactor: Pimpl leveldb::batch for CDBBatch (TheCharlatan)
b9870c920d refactor: Split dbwrapper CDBatch::Erase implementation (TheCharlatan)
532ee812a4 refactor: Split dbwrapper CDBBatch::Write implementation (TheCharlatan)
afc534df9a refactor: Wrap DestroyDB in dbwrapper helper (TheCharlatan)
Pull request description:
Leveldb headers are currently included in the `dbwrapper.h` file and thus available to many of Bitcoin Core's source files. However, leveldb-specific functionality should be abstracted by the `dbwrapper` and does not need to be available to the rest of the code. Having leveldb included in a widely-used header such as `dbwrapper.h` bloats the entire project's header tree.
The `dbwrapper` is a key component of the libbitcoinkernel library. Future users of this library would not want to contend with having the leveldb headers exposed and potentially polluting their project's namespace.
For these reasons, the leveldb headers are removed from the `dbwrapper` by moving leveldb-specific code to the implementation file and creating a [pimpl](https://en.cppreference.com/w/cpp/language/pimpl) where leveldb member variables are indispensable. As a final step, the leveldb include flags are removed from the `BITCOIN_INCLUDES` and moved to places where the dbwrapper is compiled.
---
This pull request is part of the [libbitcoinkernel project](https://github.com/bitcoin/bitcoin/issues/27587), and more specifically its stage 1 step 3 "Decouple most non-consensus headers from libbitcoinkernel".
ACKs for top commit:
stickies-v:
re-ACK d8f1222ac5
MarcoFalke:
ACK d8f1222ac5🔠
Tree-SHA512: 0f58309be165af0162e648233451cd80fda88726fc10c0da7bfe4ec2ffa9afe63fbf7ffae9493698d3f39653b4ad870c372eee652ecc90ab1c29d86c387070f3
1c976c691c tidy: Integrate bicoin-tidy clang-tidy plugin (fanquake)
7de23cceb8 refactor: fix unterminated LogPrintf()s (fanquake)
0a1029aa29 lint: remove /* Continued */ markers from codebase (fanquake)
910007995d lint: remove lint-logs.py (fanquake)
d86a83d6b8 lint: drop DIR_IWYU global (fanquake)
Pull request description:
Demo of integrating the [bitcoin-tidy](https://github.com/theuni/bitcoin-tidy-plugin), [clang-tidy plugin](https://clang.llvm.org/extra/clang-tidy/) written by theuni into our tidy CI job.
The plugin currently has a single check, `bitcoin-unterminated-logprintf`. This would replace our current Python driven, `git-grep`-based, `.cpp` file only, lint-logs linter.
ACKs for top commit:
TheCharlatan:
ACK 1c976c691c
theuni:
ACK 1c976c691c
MarcoFalke:
re-ACK 1c976c691c👠
Tree-SHA512: 725b45c70e431d48e6f276671e05c694e10b6047cae1a31906ac3ee9093bc8105fb226b36a5bac6709557526ca6007222112d66aecec05a574434edc4897e4b8
fa69e3a95c Remove unused MessageStartChars parameters from BlockManager methods (MarcoFalke)
Pull request description:
Seems odd to expose these for mocking, when it is not needed.
Fix this by removing the the unused parameters and use the already existing member field instead.
ACKs for top commit:
Empact:
utACK fa69e3a95c
dergoegge:
utACK fa69e3a95c
Tree-SHA512: 7814e9560abba8d9c0926bcffc70f92e502d22f543af43671248f6fcd1433f35238553c0f05123fde6d8e0f80261af0ab0500927548115153bd68d57fe2da746
1b52d16d07 p2p: network-specific management of outbound connections (Martin Zumsande)
65cff00cee test: Add test for outbound protection by network (Martin Zumsande)
034f61f83b p2p: Protect extra full outbound peers by network (Martin Zumsande)
654d9bc276 p2p: Introduce data struct to track connection counts by network (Amiti Uttarwar)
Pull request description:
This is joint work with mzumsande.
This is a proposal to diversify outbound connections with respect to reachable networks. The existing logic evaluates peers for connection based purely on the frequency of available addresses in `AddrMan`. This PR adds logic to automatically connect to alternate reachable networks and adds eviction logic that protects one existing connection to each network.
For instance, if `AddrMan` is populated primarily with IPv4 and IPv6 addresses and only a handful of onion addresses, it is likely that we won't establish any automatic outbound connections to Tor, even if we're capable of doing so. For smaller networks like CJDNS, this is even more of an issue and often requires adding manual peers to ensure regularly being connected to the network.
Connecting to multiple networks improves resistance to eclipse attacks for individual nodes. It also benefits the entire p2p network by increasing partition resistance and privacy in general.
The automatic connections to alternate networks is done defensively, by first filling all outbound slots with random addresses (as in the status quo) and then adding additional peers from reachable networks the node is currently not connected to. This approach ensures that outbound slots are not left unfilled while attempting to connect to a network that may be unavailable due to a technical issue or misconfiguration that bitcoind cannot detect.
Once an additional peer is added and we have one more outbound connection than we want, outbound eviction ensures that peers are protected if they are the only ones for their network.
Manual connections are also taken into account: If a user already establishes manual connections to a trusted peer from a network, there is no longer a need to make extra efforts to ensure we also have an automatic connection to it (although this may of course happen by random selection).
ACKs for top commit:
naumenkogs:
ACK 1b52d16d07
vasild:
ACK 1b52d16d07
Tree-SHA512: 5616c038a5fbb868d4c46c5963cfd53e4599feee25db04b0e18da426d77d22e0994dc4e1da0b810f5b457f424ebbed3db1704f371aa6cad002b3565b20170ec0
If a peer is the only one of its network, protect it from eviction.
This improves the diversity of outbound connections with respect to
reachable networks.
Co-authored-by: Amiti Uttarwar <amiti@uttarwar.org>
Rather than using a bloom filter to track announced invs, simply allow
a peer to request any tx that entered the mempool prior to the last INV
message we sent them. This also obsoletes the UNCONDITIONAL_RELAY_DELAY.
When processing `CMPCTBLOCK` message, at some moments
we can need to process cmpct block txns, since all messages
are handled by ProcessMessage, we call ProcessMessage
all over again. For this reason, it creates a function called
`ProcessCompactBlockTxns` to process it.
DataStream Serialize method has surprising behavior because it just serializes
raw bytes without a length prefix. When you serialize a string or vector, a
length prefix is serialized before the raw object contents so the object can be
unambiguously deserialized later. But DataStreams don't support deserializing
at all and just dump the raw bytes.
Having this inconsistency is not necessary and could be confusing (see
https://github.com/bitcoin/bitcoin/pull/27790#discussion_r1212315030) so this
PR just drops the DataStream::Serialize method.
fb02a3cd1a p2p: Log addresses of stalling peers (Martin Zumsande)
Pull request description:
This was suggested in #27705 by ArmchairCryptologist.
It allows node operators that have the `-logips` option enabled to better identify potentially misbehaving peers and maybe ban them.
This is especially helpful in case of inbound peers for which (dis)connections aren't logged per default, so it's impossible to use the debug log to connect their `nodeId` to an address unless the very noisy `net` debugging is enabled.
In case of outbound peers for which the address is potentially logged when establishing the connection, this just adds some convenience.
ACKs for top commit:
stratospher:
tACK fb02a3c.
jamesob:
github ACK fb02a3cd1a
0xB10C:
Untested ACK fb02a3cd1a
instagibbs:
utACK fb02a3cd1a
Tree-SHA512: 2080f794c715bd36143405828b4b0e1be859095caf8f8a0c20dd2a4b64d192d78fee0fa350a2bb7c39848718332c4dd4d8edb2cc8d22095b65afe710591f7ccb
A single outbound slot is required, so if the first two slots
are taken by inbound in-flights, the node will reject additional
unless they are coming from outbound.
This means in the case where a fast sybil peer is attempting to
stall out a node, a single high bandwidth outbound peer can
mitigate the attack.
This is a change in behavior so that if for some reason we request a block from a peer, we don't allow an unsolicited CMPCT_BLOCK announcement for that same block to cause a request for a full block from the uninvited peer (as some type of request is already outstanding from the original peer)
5b3406094f net_processing: Boost inv trickle rate (Anthony Towns)
228e9201ef txmempool: have CompareDepthAndScore sort missing txs first (Anthony Towns)
Pull request description:
Couple of performance improvements when draining the inventory-to-send queue:
* drop txs that have already been evicted from the mempool (or included in a block) immediately, rather than at the end of processing
* marginally increase outgoing trickle rate during spikes in tx volume
ACKs for top commit:
willcl-ark:
ACK 5b34060
instagibbs:
ACK 5b3406094f
darosior:
utACK 5b3406094f
glozow:
code review ACK 5b3406094f
dergoegge:
utACK 5b3406094f
Tree-SHA512: 155cd3b5d150ba3417c1cd126f2be734497742e85358a19c9d365f4f97c555ff9e846405bbeada13c3575b3713c3a7eb2f780879a828cbbf032ad9a6e5416b30
This is a commit in preparation for the next few commits. The functions
are moved to methods to avoid their re-declaration for the purpose of
passing in BlockManager options.
The functions that were now moved into the BlockManager should no longer
use the params as an argument, but instead use the member variable.
In the moved ReadBlockFromDisk and UndoReadFromDisk, change
the function signature to accept a reference to a CBlockIndex instead of
a raw pointer. The pointer is expected to be non-null, so reflect that
in the type.
To allow for the move of functions to BlockManager methods all call
sites require an instantiated BlockManager, or a callback to one.
If transactions are being added to the mempool at a rate faster than 7tx/s
(INVENTORY_BROADCAST_PER_SECOND) then peers' inventory_to_send queue can
become relatively large. If this happens, increase the number of txids
we include in an INV message (normally capped at 35) by 5 for each 1000
txids in the queue.
This will tend to clear a temporary excess out reasonably quickly; an
excess of 4000 invs to send will be cleared down to 1000 in about 30
minutes, while an excess of 20000 invs would be cleared down to 1000 in
about 60 minutes.
Under which circumstances we process received 'mempool' P2P messages
caused confusion in #27426. Rather than bikeshedding the formulation
of the IF-statement, this adds a comment clarifing when we process
the message. Also, correcting the comment of `m_send_mempool`.
Co-authored-by: willcl-ark <will8clark@gmail.com>
be55f545d5 move-only: Extract common/args and common/config.cpp from util/system (TheCharlatan)
Pull request description:
This pull request is part of the `libbitcoinkernel` project https://github.com/bitcoin/bitcoin/issues/24303https://github.com/bitcoin/bitcoin/projects/18 and more specifically its "Step 2: Decouple most non-consensus code from libbitcoinkernel". It is part of a series of patches splitting up the `util/system` files. Its preceding pull request is https://github.com/bitcoin/bitcoin/pull/27254.
The pull request contains an extraction of ArgsManager related functions from util/system into their own common/ file.
The background of this commit is an ongoing effort to decouple the libbitcoinkernel library from the ArgsManager. The ArgsManager belongs into the common library, since the kernel library should not depend on it. See [doc/design/libraries.md](https://github.com/bitcoin/bitcoin/blob/master/doc/design/libraries.md) for more information on this rationale.
ACKs for top commit:
MarcoFalke:
re-ACK be55f545d5🚲
ryanofsky:
Code review ACK be55f545d5. Just small cleanups since the last review.
hebasto:
ACK be55f545d5, I have reviewed the code and it looks OK, I agree it can be merged.
Tree-SHA512: 90eb03334af0155b823030b4f2ecf286d35058d700ee2ddbbaa445be19e31eb0fe982656f35bd14ecee3ad2c3d0db3746855cb8f3777eff7253713e42873e111
0076bed45e logging: log ASN when using `-asmap` (brunoerg)
9836c76ae0 net: add `GetMappedAS` in `CConnman` (brunoerg)
Pull request description:
When using `-asmap`, you can check the ASN assigned to the peers only with the RPC command `getpeerinfo` (check `mapped_as` field), however, it's not possible to check it in logs (e.g. see in logs the ASN of the peers when a new outbound peer has been connected). This PR includes the peers' ASN in debug output when using `-asmap`.
Obs: Open this primarily to chase some Concept ACK, I've been using this on my node to facilitate to track the peers' ASN especially when reading the logs.
ACKs for top commit:
Sjors:
tACK 0076bed45e
jamesob:
ACK 0076bed45e ([`jamesob/ackr/27412.1.brunoerg.logging_net_add_asn_from`](https://github.com/jamesob/bitcoin/tree/ackr/27412.1.brunoerg.logging_net_add_asn_from))
achow101:
ACK 0076bed45e
Tree-SHA512: c19cd11e8ab49962021f390459aadf6d33d221ae9a2c3df331a25d6865a8df470e2c8828f6e5219b8a887d6ab5b3450d34be9e26c00cca4d223b4ca64d51111b
This is an extraction of ArgsManager related functions from util/system
into their own common file.
Config file related functions are moved to common/config.cpp.
The background of this commit is an ongoing effort to decouple the
libbitcoinkernel library from the ArgsManager. The ArgsManager belongs
into the common library, since the kernel library should not depend on
it. See doc/design/libraries.md for more information on this rationale.
55c4795c57 [net processing] Use TxRelay::m_relay_txs over CNode::m_relays_txs (dergoegge)
Pull request description:
`CNode::m_relays_txs` is meant to only be used for the eviction logic in `net`. `TxRelay::m_relay_txs` will hold the same value and is meant to be used on the application layer to determine if we will/should relay transactions to a peer.
(Shameless plug: we should really better specify the interface for updating eviction data to avoid refactors like this in the future -> #25572)
ACKs for top commit:
MarcoFalke:
lgtm ACK 55c4795c57
Tree-SHA512: 59cfd23e32568fd96cda5570790e518242a6c76d4edf5b7d1a2a7f9724d590d2a38395504e05be0af4e98dd5c0056fc0be6568eab2818934692483a186e5181d
Taking cs_main is no longer necessary since we moved
`m_recently_announced_invs` to `Peer` and `mapRelay` is actually only
accessed from the message processing thread.
3566aa7d49 [net] Remove CNode friends (dergoegge)
3eac5e7cd1 [net] Add CNode helper for send byte accounting (dergoegge)
60441a3432 scripted-diff: [net] Rename CNode process queue members (dergoegge)
6693c499f7 [net] Make cs_vProcessMsg a non-recursive mutex (dergoegge)
23d9352654 [net] Make CNode msg process queue members private (dergoegge)
897e342d6e [net] Encapsulate CNode message polling (dergoegge)
cc5cdf8776 [net] Deduplicate marking received message for processing (dergoegge)
ad44aa5c64 [net] Add connection type getter to CNode (dergoegge)
Pull request description:
We should define clear interfaces between CNode, CConnman and PeerManager. This PR makes a small step in that direction by ending the friendship of CNode, CConnman and ConnmanTestMsg. CNode's message processing queue is made private in the process and its mutex is turned into a non-recursive mutex.
ACKs for top commit:
jnewbery:
utACK 3566aa7d49
vasild:
ACK 3566aa7d49
theStack:
re-ACK 3566aa7d49
brunoerg:
re-ACK 3566aa7d49
Tree-SHA512: 26b87da5054e32401b693b2904e9c5f40e35a53937c0b6cf44b8597034ad07bacf27d87cdffc54d3e7ccfebde4231ef30a38d326f88cc18133bbb34688ead567
c9d548c91f net: remove CService::ToStringPort() (Vasil Dimov)
fd4f0f41e9 gui: simplify OptionsDialog::updateDefaultProxyNets() (Vasil Dimov)
96c791dd20 net: remove CService::ToString() use ToStringAddrPort() instead (Vasil Dimov)
944a9de08a net: remove CNetAddr::ToString() and use ToStringAddr() instead (Vasil Dimov)
043b9de59a scripted-diff: rename ToStringIP[Port]() to ToStringAddr[Port]() (Vasil Dimov)
Pull request description:
Before this PR we had the somewhat confusing combination of methods:
`CNetAddr::ToStringIP()`
`CNetAddr::ToString()` (duplicate of the above)
`CService::ToStringIPPort()`
`CService::ToString()` (duplicate of the above, overrides a non-virtual method from `CNetAddr`)
`CService::ToStringPort()`
Avoid [overriding non-virtual methods](https://github.com/bitcoin/bitcoin/pull/25349/#issuecomment-1185226396).
"IP" stands for "Internet Protocol" and while sometimes "IP addresses" are called just "IPs", it is incorrect to call Tor or I2P addresses "IPs". Thus use "Addr" instead of "IP".
Change the above to:
`CNetAddr::ToStringAddr()`
`CService::ToStringAddrPort()`
The changes touch a lot of files, but are mostly mechanical.
ACKs for top commit:
sipa:
utACK c9d548c91f
achow101:
ACK c9d548c91f
jonatack:
re-ACK c9d548c91f only change since my previous reviews is rebase, but as a sanity check rebased to current master and at each commit quickly re-reviewed and re-verified clean build and green unit tests
LarryRuane:
ACK c9d548c91f
Tree-SHA512: 633fb044bdecf9f551b5e3314c385bf10e2b78e8027dc51ec324b66b018da35e5b01f3fbe6295bbc455ea1bcd1a3629de1918d28de510693afaf6a52693f2157
faf7b4f1fc Add BlockManager::IsPruneMode() (MarcoFalke)
fae71fe27e Add BlockManager::GetPruneTarget() (MarcoFalke)
fa0f0436d8 Add BlockManager::LoadingBlocks() (MarcoFalke)
Pull request description:
Requested in https://github.com/bitcoin/bitcoin/pull/25781#discussion_r1061323795, but adding getters seems unrelated from removing globals, so I split it out for now.
ACKs for top commit:
dergoegge:
Code review ACK faf7b4f1fc
brunoerg:
crACK faf7b4f1fc
Tree-SHA512: 204d0e9a0e8b78175482f89b4ce620fba0e65d8e49ad845d187af44d3843f4c733a01bac1ffe5a5319f524d8346123693a456778b69d6c75268c447eb8839642
39b93649c4 test: add functional test for IBD stalling logic (Martin Zumsande)
0565951f34 p2p: Make block stalling timeout adaptive (Martin Zumsande)
Pull request description:
During IBD, there is the following stalling mechanism if we can't proceed with assigning blocks from a 1024 lookahead window because all of these blocks are either already downloaded or in-flight: We'll mark the peer from which we expect the current block that would allow us to advance our tip (and thereby move the 1024 window ahead) as a possible staller. We then give this peer 2 more seconds to deliver a block (`BLOCK_STALLING_TIMEOUT`) and if it doesn't, disconnect it and assign the critical block we need to another peer.
Now the problem is that this second peer is immediately marked as a potential staller using the same mechanism and given 2 seconds as well - if our own connection is so slow that it simply takes us more than 2 seconds to download this block, that peer will also be disconnected (and so on...), leading to repeated disconnections and no progress in IBD. This has been described in #9213, and I have observed this when doing IBD on slower connections or with Tor - sometimes there would be several minutes without progress, where all we did was disconnect peers and find new ones.
The `2s` stalling timeout was introduced in #4468, when blocks weren't full and before Segwit increased the maximum possible physical size of blocks - so I think it made a lot of sense back then.
But it would be good to revisit this timeout now.
This PR makes the timout adaptive (idea by sipa):
If we disconnect a peer for stalling, we now double the timeout for the next peer (up to a maximum of 64s). If we connect a block, we half it again up to the old value of 2 seconds. That way, peers that are comparatively slower will still get disconnected, but long phases of disconnecting all peers shouldn't happen anymore.
Fixes#9213
ACKs for top commit:
achow101:
ACK 39b93649c4
RandyMcMillan:
Strong Concept ACK 39b93649c4
vasild:
ACK 39b93649c4
naumenkogs:
ACK 39b93649c4
Tree-SHA512: 85bc57093b2fb1d28d7409ed8df5a91543909405907bc129de7c6285d0810dd79bc05219e4d5aefcb55c85512b0ad5bed43a4114a17e46c35b9a3f9a983d5754
fa035fe2d6 Remove unused CDataStream::SetType (MarcoFalke)
fa29e73cda Use DataStream where possible (MarcoFalke)
fa9becfe1c streams: Add DataStream without ser-type and ser-version (MarcoFalke)
Pull request description:
This was done in the context of https://github.com/bitcoin/bitcoin/pull/25284 , but I think it also makes sense standalone.
The basic idea is that serialization type should not be initialized when it is not needed. Same for the serialization version.
So do this here for `DataStream`. `CDataStream` remains in places where it is not yet possible.
ACKs for top commit:
stickies-v:
re-ACK [fa035fe](fa035fe2d6)
aureleoules:
diff re-ACK fa035fe2d6fa0e6640ba..fa035fe2d6
Tree-SHA512: cb5e53d0df7c94319ffadc6ea1d887fc38516decaf43f0673396d79cc62d450a1a61173654a91b8c2b52d2cecea53fe4a500b8f6466596f35731471163fb051c
c58c249a5b net_processing: indicate more work to do when orphans are ready to reconsider (Anthony Towns)
ecb0a3e425 net_processing: Don't process tx after processing orphans (Anthony Towns)
c583775706 net_processing: only process orphans before messages (Anthony Towns)
be2304676b txorphange: Drop redundant originator arg from GetTxToReconsider (Anthony Towns)
a4fe09973a txorphanage: index workset by originating peer (Anthony Towns)
Pull request description:
We currently process orphans by assigning them to the peer that provided a missing parent; instead assign them to the peer that provided the orphan in the first place. This prevents a peer from being able to marginally delay another peer's transactions and also simplifies the internal API slightly. Because we're now associating orphan processing with the peer that provided the orphan originally, we no longer process orphans immediately after receiving the parent, but defer until a future call to `ProcessMessage`.
Based on #26295
ACKs for top commit:
naumenkogs:
utACK c58c249a5b
glozow:
ACK c58c249a5b
mzumsande:
Code Review ACK c58c249a5b
Tree-SHA512: 3186c346f21e60440266a2a80a9d23d7b96071414e14b2b3bfe50457c04c18b1eab109c3d8c2a7726a6b10a2eda1f0512510a52c102da112820a26f5d96f12de
When PR#15644 made orphan processing interruptible, it also introduced a
potential 100ms delay between processing of the first and second newly
reconsiderable orphan, because it didn't check if the orphan work set
was non-empty after invoking ProcessMessage(). This adds that check, so
that ProcessMessages() will return true if there are orphans to process,
usually avoiding the 100ms delay in CConnman::ThreadMessageHandler().
If we made progress on orphans, consider that enough work for this peer
for this round of ProcessMessages. This also allows cleaning up the api
for TxOrphange:GetTxToReconsider().
Previously, when we processed a new tx we would attempt to ATMP any
orphans that considered the new tx a parent immediately, but would only
accept at most one such tx, leaving any others to be considered on a
future run of ProcessMessages(). With this patch, we don't attempt any
orphan processing immediately after receiving a tx, instead deferring
all of them until the next call to ProcessMessages().
Both methods do the same thing, so simplify to having just one.
`ToString()` is too generic in this case and it is unclear what it does,
given that there are similar methods:
`ToStringAddr()` (inherited from `CNetAddr`),
`ToStringPort()` and
`ToStringAddrPort()`.
956c67059c refactor, doc: Improve SetupAddressRelay call in version processing (Martin Zumsande)
3c43d9db1e p2p: Don't self-advertise during VERSION processing (Gleb Naumenko)
Pull request description:
This picks up the last commit from #19843.
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()` 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`.
ACKs for top commit:
stratospher:
ACK 956c670
naumenkogs:
ACK 956c67059c
amitiuttarwar:
reACK 956c67059c
Tree-SHA512: 933d40615289f055c022170dde7bad0ac0a1d4be377538bfe9ba64375cfeb03bcd803901591f0739ac4850c880e8475a68fd1ab0330800030ab7f19e38c00274
fa579f3063 refactor: Pass reference to last header, not pointer (MacroFake)
Pull request description:
It is never a nullptr, otherwise an assertion would fire in UpdatePeerStateForReceivedHeaders.
Passing a reference makes the code easier to read and less brittle.
ACKs for top commit:
john-moffett:
ACK fa579f3
aureleoules:
ACK fa579f3063
Tree-SHA512: 9725195663a31df57ae46bb7b11211cc4963a8f3d100f60332bfd4a3f3327a73ac978b3172e3007793cfc508dfc7c3a81aab57a275a6963a5ab662ce85743fd0
38941a703e refactor: Move `txmempool_entry.h` --> `kernel/mempool_entry.h` (Hennadii Stepanov)
Pull request description:
This PR addresses the https://github.com/bitcoin/bitcoin/pull/17786#discussion_r1027818360:
> why not move it to the right place, that is to `kernel/txmempool_entry.h`?
ACKs for top commit:
MarcoFalke:
review ACK 38941a703e📊
Tree-SHA512: 0145974b63b67ca1d9d89af2dd9d4438beca480c16a563f330da05fec49b8394d7ba20ed83cf7d50b2e19454e006978ebed42b0e07887b98d00210f3201ce9ba
f39d9269eb rpc: warn that nodes ignore requests for old stale blocks (Sjors Provoost)
Pull request description:
Adds warning to RPC help that `getblockfrompeer` is of little use for stale blocks that are more than a month old.
This is an anti-fingerprinting measure. See `BlockRequestAllowed` in `net_processing`.
It's been in Bitcoin Core since 2014, introduced in #2910 and later improved to not rely on checkpoints.
Older and alternative clients might still serve these blocks, so not throwing an error.
Allowing whitelisted nodes to fetch these blocks anyway might be nice.
ACKs for top commit:
fjahr:
Code review ACK f39d9269eb
Tree-SHA512: db88f9f7521289640c5e629c840dda1c2c3ab70d458e9e7136c60fbaeb02acfb36dc093502d83d4c098c331e22aab81bf8f4c4961d805e3bde0f8f3cfe68d968
1984db1d50 refactor: Rename local variable to distinguish it from type alias (Hennadii Stepanov)
Pull request description:
The `txiter` type alias is declared in the `txmempool.h`: 9e59d21fbe/src/txmempool.h (L406)
ACKs for top commit:
stickies-v:
ACK 1984db1d5
vasild:
ACK 1984db1d50
jarolrod:
ACK 1984db1d50
Tree-SHA512: 127bfb62627e2d79d8cdb0bd0ac11b3737568c3631b54b2d1e37984f673a1f60edf7bc102a269f7eb40e4bb124b910b924a89475c6a6ea978b2171219fa30685
8f2dac5409 [test] Add p2p_tx_privacy.py (dergoegge)
ce63fca13e [net processing] Assume that TxRelay::m_tx_inventory_to_send is empty pre-verack (dergoegge)
845e3a34c4 [net processing] Ensure transaction announcements are only queued for fully connected peers (dergoegge)
Pull request description:
`TxRelay::m_next_inv_send_time` is initialized to 0, which means that any txids in `TxRelay::m_tx_inventory_to_send` will be announced on the first call to `PeerManagerImpl::SendMessages` for a fully connected peer (i.e. it completed the version handshake).
Prior to #21160, `TxRelay::m_tx_inventory_to_send` was guaranteed to be empty on the first `SendMessages` call, as transaction announcements were only queued for fully connected peers. #21160 replaced a `CConnman::ForEachNode` call with a loop over `PeerManagerImpl::m_peer_map`, in which the txid for a transaction to be relayed is added to `TxRelay::m_tx_inventory_to_send` for all peers. Even for those peers that have not completed the version handshake. Prior to the PR this was not the case as `ForEachNode` has a "fully connected check" before calling a function for each node.
ACKs for top commit:
MarcoFalke:
ACK 8f2dac5409🔝
jnewbery:
utACK 8f2dac5409
Tree-SHA512: e9eaccf7e00633ee0806fff1068b0e413a69a5e389d96c9659f68079915a6381ad5040c61f716cfcde77931d1b563b1049da97a232a95c6cd8355bd3d13404b9
This commit documents our assumption about
TxRelay::m_tx_inventory_to_send being empty prior to version handshake
completion.
The added Assume acts as testing oracle for our fuzzing tests to
potentially detect if the assumption is violated.
46339d29b1 test, refactor: Reorder sendtxrcncl tests for better readability (Gleb Naumenko)
14263c13f1 p2p, refactor: Extend logs for unexpected sendtxrcncl (Gleb Naumenko)
87493e112e p2p, test, refactor: Minor code improvements (Gleb Naumenko)
00c5dec818 p2p: Clarify sendtxrcncl policies (Gleb Naumenko)
ac6ee5ba21 test: Expand unit and functional tests for txreconciliation (Gleb Naumenko)
bc84e24a4f p2p, refactor: Switch to enum class for ReconciliationRegisterResult (Gleb Naumenko)
a60f729e29 p2p: Drop roles from sendtxrcncl (Gleb Naumenko)
6772cbf69c tests: stabilize sendtxrcncl test (Gleb Naumenko)
Pull request description:
Non-trivial changes include:
- Getting rid of roles in `sendtxrcncl` message (summarized in the [BIP PR](https://github.com/bitcoin/bips/pull/1376));
- Disconnect the peer if it send `sendtxrcncl` although we are in `blocksonly` and notified the peer with `fRelay=0`;
- Don't send `sendtxrcncl` to feeler connections.
ACKs for top commit:
vasild:
ACK 46339d29b1
ariard:
ACK 46339d2
mzumsande:
Code Review ACK 46339d29b1
Tree-SHA512: b5cc6934b4670c12b7dbb3189e739ef747ee542ec56678bf4e4355bfb481b746d32363c173635685b71969b3fe4bd52b1c8ebd3ea3b35c82044bba69220f6417
7082ce3e88 scripted-diff: rename and de-globalise g_cs_orphans (Anthony Towns)
733d85f79c Move all g_cs_orphans locking to txorphanage (Anthony Towns)
a936f41a5d txorphanage: make m_peer_work_set private (Anthony Towns)
3614819864 txorphange: move orphan workset to txorphanage (Anthony Towns)
6f8e442ba6 net_processing: Localise orphan_work_set handling to ProcessOrphanTx (Anthony Towns)
0027174b39 net_processing: move ProcessOrphanTx docs to declaration (Anthony Towns)
9910ed755c net_processing: Pass a Peer& to ProcessOrphanTx (Anthony Towns)
89e2e0da0b net_processing: move extra transactions to msgproc mutex (Anthony Towns)
ff8d44d196 Remove unnecessary includes of txorphange.h (Anthony Towns)
Pull request description:
Moves extra transactions to be under the `m_msgproc_mutex` lock rather than `g_cs_orphans` and refactors orphan handling so that the lock can be internal to the `TxOrphange` class.
ACKs for top commit:
dergoegge:
Code review ACK 7082ce3e88
glozow:
ACK 7082ce3e88 via code review and some [basic testing](https://github.com/glozow/bitcoin/blob/review-26295/src/test/orphanage_tests.cpp#L150). I think putting txorphanage in charge of handling peer work sets is the right direction.
Tree-SHA512: 1ec454c3a69ebd45ff652770d6a55c6b183db71aba4d12639ed70f525f0035e069a81d06e9b65b66e87929c607080a1c5e5dcd2ca91eaa2cf202dc6c02aa6818
This code was a bit hard to understand, so make it less dense and
add more explanations. Doesn't change behavior.
Co-authored-by: Amiti Uttarwar <amiti@uttarwar.org>
c8dc0e3eaa refactor: Inline `CTxMemPoolEntry` class's functions (Hennadii Stepanov)
75bbe594e5 refactor: Move `CTxMemPoolEntry` class to its own module (Hennadii Stepanov)
Pull request description:
This PR:
- gets rid of the `policy/fees` -> `txmempool` -> `policy/fees` circular dependency
- is an alternative to #13949, which nukes only one circular dependency
ACKs for top commit:
ryanofsky:
Code review ACK c8dc0e3eaa. Just include and whitespace changes since last review, and there's a moveonly commit now so it's very easy to review
theStack:
Code-review ACK c8dc0e3eaa
glozow:
utACK c8dc0e3eaa, agree these changes are an improvement.
Tree-SHA512: 36ece824e6ed3ab1a1e198b30a906c8ac12de24545f840eb046958a17315ac9260c7de26e11e2fbab7208adc3d74918db7a7e389444130f8810548ca2e81af41
fa24239a1c net: Avoid SetTxRelay for feeler connections (MacroFake)
Pull request description:
Seems odd to reserve memory for the struct (the heaviest member being `m_tx_inventory_known_filter`) when it is never used.
This also avoids sending out `msg_sendtxrcncl` before disconnecting. This shouldn't matter, as other messages, such as `msg_wtxidrelay`, `msg_sendaddrv2`, `msg_verack` or `msg_getaddr` are still sent. Though, it allows to test the changes here as a side-effect.
ACKs for top commit:
naumenkogs:
ACK fa24239a1c
vasild:
ACK fa24239a1c
jonatack:
ACK fa24239a1c
mzumsande:
ACK fa24239a1c
Tree-SHA512: d7604c7eb4df8f2de811e600bdd312440ee03e508d3a0f09ae79f7f2d3eeec663bfd47a2d079fa50b756d61e35dfa998de068a7b9afaf35378fa0e62a538263d
`m_headers_sync` is already reset in IsContinuationOfLowWorkHeadersSync
if there is a failure, so there is no need to also reset in
TryLowWorkHeaderSync.
aaaa7bd0ba iwyu: Add missing includes (MacroFake)
fa9ebec096 Remove g_parallel_script_checks (MacroFake)
fa7c834b9f Move ::fCheckBlockIndex into ChainstateManager (MacroFake)
fa43188d86 Move ::fCheckpointsEnabled into ChainstateManager (MacroFake)
cccca83099 Move ::nMinimumChainWork into ChainstateManager (MacroFake)
fa29d0b57c Move ::hashAssumeValid into ChainstateManager (MacroFake)
faf44876db Move ::nMaxTipAge into ChainstateManager (MacroFake)
Pull request description:
It seems preferable to assign globals to a class (in this case `ChainstateManager`), than to leave them dangling. This should clarify scope for code-readers, as well as clarifying unit test behaviour.
ACKs for top commit:
dergoegge:
Code review ACK aaaa7bd0ba
ryanofsky:
Code review ACK aaaa7bd0ba. No changes since last review, other than rebase
aureleoules:
reACK aaaa7bd0ba
Tree-SHA512: 83ec3ba0fb4f1dad95810d4bd4e578454e0718dc1bdd3a794cc4e48aa819b6f5dad4ac4edab3719bdfd5f89cbe23c2740a50fd56c1ff81c99e521c5f6d4e898d
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:
ACK 7ad15d1100
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:
dergoegge:
ACK dddd1acf58
naumenkogs:
ACK dddd1acf58
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:
achow101:
ACK a3789c700b
brunoerg:
ACK a3789c700b
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.
