ba84a25dee [doc] update mempool-replacements.md for incremental relay feerate change (glozow)
18720bc5d5 [doc] release note for min feerate changes (glozow)
6da5de58ca [policy] lower default minrelaytxfee and incrementalrelayfee to 100sat/kvB (glozow)
2e515d2897 [prep/test] make wallet_fundrawtransaction's minrelaytxfee assumption explicit (glozow)
457cfb61b5 [prep/util] help MockMempoolMinFee handle more precise feerates (glozow)
3eab8b7240 [prep/test] replace magic number 1000 with respective feerate vars (glozow)
5f2df0ef78 [miner] lower default -blockmintxfee to 1sat/kvB (glozow)
d6213d6aa1 [doc] assert that default min relay feerate and incremental are the same (glozow)
1fbee5d7b6 [test] explicitly check default -minrelaytxfee and -incrementalrelayfee (glozow)
72dc18467d [test] RBF rule 4 for various incrementalrelayfee settings (glozow)
85f498893f [test] check bypass of minrelay for various minrelaytxfee settings (glozow)
e5f896bb1f [test] check miner doesn't select 0fee transactions (glozow)
Pull request description:
ML post for discussion about the general concept, how this impacts the wider ecosystem, philosophy about minimum feerates, etc: https://delvingbitcoin.org/t/changing-the-minimum-relay-feerate/1886
This PR is inspired by #13922 and #32959 to lower the minimum relay feerate in response to bitcoin's exchange rate changes in the last ~10 years. It lowers the default `-minrelaytxfee` and `-incrementalrelayfee`, and knocks `-blockmintxfee` down to the minimum nonzero setting. Also adds some tests for the settings and pulls in #32750.
The minimum relay feerate is a DoS protection rule, representing a price on the network bandwidth used to relay transactions that have no PoW. While relay nodes don't all collect fees, the assumption is that if nodes on the network use their resources to relay this transaction, it will reach a miner and the attacker's money will be spent once it is mined. The incremental relay feerate is similar: it's used to price the relay of replacement transactions (the additional fees need to cover the new transactions at this feerate) and evicted transactions (following a trim, the new mempool minimum feerate is the package feerate of what was removed + incremental).
Also note that many nodes on the network have elected to relay/mine lower feerate transactions. Miners (some say up to 85%) are choosing to mine these low feerate transactions instead of leaving block space unfilled, but these blocks have extremely poor compact block reconstruction rates with nodes that rejected or didn't hear about those transactions earlier.
- https://github.com/bitcoin/bitcoin/pull/33106#issuecomment-3155627414
- https://x.com/caesrcd/status/1947022514267230302
- https://mempool.space/block/00000000000000000001305770e0aa279dcd8ba8be18c3d5cf736a26f77e06fd
- https://mempool.space/block/00000000000000000001b491649ec030aa8e003e1f4f9d3b24bb99ba16f91e97
- https://x.com/mononautical/status/1949452586391855121
While it wouldn't make sense to loosen DoS restrictions recklessly in response to these events, I think the current price is higher than necessary, and this motivates us changing the default soon. Since the minimum relay feerate defines an amount as too small based on what it costs the attacker, it makes sense to consider BTC's conversion rate to what resources you can buy in the "real world."
Going off of [this comment](https://github.com/bitcoin/bitcoin/pull/32959#issuecomment-3095260286) and [this comment](https://github.com/bitcoin/bitcoin/pull/33106#issuecomment-3142444090)
- Let's say an attacker wants to use/exhaust the network's bandwidth, and has the choice between renting resources from a commercial provider and getting the network to "spam" itself it by sending unconfirmed transactions. We'd like the latter to be more expensive than the former.
- The bandwidth for relaying a transaction across the network is roughly its serialized size (plus relay overhead) x number of nodes. A 1000vB transaction is 1000-4000B serialized. With 100k nodes, that's 0.1-0.4GB
- If the going rate for ec2 bandwidth is 10c/GB, that's like 1-4c per kvB of transaction data
- Then a 1000vB transaction should pay at least 4c
- $0.04 USD is 40 satoshis at 100k USD/BTC
- Baking in some margin for changes in USD/BTC conversion rate, number of nodes (and thus bandwidth), and commercial service costs, I think 50-100 satoshis is on the conservative end but in the right ballpark
- At least 97% of the recent sub-1sat/vB transactions would be accepted with a new threshold of 0.1sat/vB: https://github.com/bitcoin/bitcoin/pull/33106#issuecomment-3156213089
List of feerates that are changed and why:
- min relay feerate: significant conversion rate changes, see above
- incremental relay feerate: should follow min relay feerate, see above
- block minimum feerate: shouldn’t be above min relay feerate, otherwise the node accepts transactions it will never mine. I've knocked it down to the bare minimum of 1sat/kvB. Now that we no longer have coin age priority (removed in v0.15), I think we can leave it to the `CheckFeeRate` policy rule to enforce a minimum entry price, and the block assembly code should just fill up the block with whatever it finds in mempool.
List of feerates that are not changed and why:
- dust feerate: this feerate cannot be changed as flexibly as the minrelay feerate. A much longer record of low feerate transactions being mined is needed to motivate a decrease there.
- maxfeerate (RPC, wallet): I think the conversion rate is relevant as well, but out of scope for this PR
- minimum feerate returned by fee estimator: should be done later. In the past, we've excluded new policy defaults from fee estimation until we feel confident they represent miner policy (e.g. #9519). Also, the fee estimator itself doesn't have support for sub-1sat/vB yet.
- all wallet feerates (mintxfee, fallbackfee, discardfee, consolidatefeerate, WALLET_INCREMENTAL_RELAY_FEE, etc.): should be done later. Our standard procedure is to do wallet changes at least 1 release after policy changes.
ACKs for top commit:
achow101:
ACK ba84a25dee
gmaxwell:
ACK ba84a25dee
jsarenik:
Tested ACK ba84a25dee
darosior:
ACK ba84a25dee
ajtowns:
ACK ba84a25dee
davidgumberg:
crACK https://github.com/bitcoin/bitcoin/pull/33106/commits/ba84a25deec0b3b9b94ee51b373e715fec995791
w0xlt:
ACK https://github.com/bitcoin/bitcoin/pull/33106/commits/ba84a25deec0b3b9b94ee51b373e715fec995791
caesrcd:
reACK ba84a25dee
ismaelsadeeq:
re-ACK ba84a25dee
Tree-SHA512: b4c35e8b506b1184db466551a7e2e48bb1e535972a8dbcaa145ce3a8bfdcc70a8807dc129460f129a9d31024174d34077154a387c32f1a3e6831f6fa5e9c399e
Let's say an attacker wants to use/exhaust the network's bandwidth, and
has the choice between renting resources from a commercial provider and
getting the network to "spam" itself it by sending unconfirmed
transactions. We'd like the latter to be more expensive than the former.
The bandwidth for relaying a transaction across the network is roughly
its serialized size (plus relay overhead) x number of nodes. A 1000vB
transaction is 1000-4000B serialized. With 100k nodes, that's 0.1-0.4GB
If the going rate for commercial services is 10c/GB, that's like 1-4c per kvB
of transaction data, so a 1000vB transaction should pay at least $0.04.
At a price of 120k USD/BTC, 100sat is about $0.12. This price allows us
to tolerate a large decrease in the conversion rate or increase in the
number of nodes.
Do not discourage nodes even when they send us consensus invalid
transactions.
Because we do not discourage nodes for transactions we consider
non-standard, we don't get any DoS protection from this check in
adversarial scenarios, so remove the check entirely both to simplify the
code and reduce the risk of splitting the network due to changes in tx
relay policy.
eb65f57f31 [test] setmocktime instead of waiting in 1p1c tests (glozow)
70772dd469 [test] cut the number of transactions involved in 1p1c DoS tests (glozow)
Pull request description:
It was brought to my attention that the runtime of this test is Too Damn High. The test is slow due to the many `wait_for_getdata`s with delays (inbound peer + txid request) and the large volume of messages sent in the dos-related tests. This PR cuts the runtime by about 60% by reducing the number of messages/transactions and using `setmocktime` instead of waiting.
On my machine, master:
```
84.51s user 1.55s system 57% cpu 2:28.53 total
```
After first commit (about 1min faster):
```
28.29s user 0.88s system 35% cpu 1:22.84 total
```
After second commit (about 30sec faster):
```
28.17s user 0.87s system 59% cpu 49.082 total
```
Reviewers should verify that the transactions in the DoS tests are still enough to cause evictions, and that the `bumpmocktime` amounts are not more than necessary.
Alternatives:
- If we don't like mocking the times, we can use outbound connections for all the peers. However, that approach won't improve the runtime as much because we impose a 2-second delay on all txid requests regardless of peer type.
- Note that `noban_tx_relay` is not relevant for this test because all delays are related to downloading, not announcing.
ACKs for top commit:
achow101:
ACK eb65f57f31
w0xlt:
ACK https://github.com/bitcoin/bitcoin/pull/33048/commits/eb65f57f319dc4e2ea8c83cf7e283c36f1c0d53b
Tree-SHA512: 6ffe1f9e5144653e2ded744cec9ddb62ad728c587705542565400a0e8f1fba4843aced4e0d929843874ca7f56f670f5871b7e009ff6be58b791ab24d2e6fcc0e
This rule was originally introduced along with a very early proposal for
package relay as a way to verify that the "correct"
child-with-unconfirmed-parents package was provided for a transaction,
where correctness was defined as all of the transactions unconfirmed
parents. However, we are not planning to introduce a protocol where
peers would be asked to send these packages.
This rule has downsides: if a transaction has multiple parents but only
1 that requires package CPFP to be accepted, the current rule prevents
us from accepting that package. Even if the other parents are already in
mempool, the p2p logic will only submit the 1p1c package, which fails
this check. See the test in p2p_1p1c_network.py
We just need enough transactions to push us above the orphanage limits
and trigger trimming. Reducing the number of transactions cuts the
runtime of this test significantly.
Also, the following tests (for which self.supports_cli = False was not
set) will now work with --usecli:
feature_fastprune.py
feature_fee_estimation.py
feature_reindex_readonly.py
feature_taproot.py
mempool_package_rbf.py
p2p_net_deadlock.py
p2p_tx_download.py
rpc_packages.py
Rather than determining a CTransaction's (w)txid as an integer by
converting it's hex value, it can be directly accessed via the
introduced `.{w,}txid_int` property.
send_message only drops the bytes in a buffer and a sync is needed to
avoid intermittent test issues. Change the name of the method to make
this more apparent during review.
-BEGIN VERIFY SCRIPT-
sed -i 's/send_message(/send_without_ping(/g' $( git grep -l 'send_message(' )
-END VERIFY SCRIPT-
Now that we track all announcers of an orphan, it's not helpful to
consider an orphan provided by a peer that didn't send us this parent.
It can only hurt our chances of finding the right orphan when there are
multiple candidates.
Adapt the 2 tests in p2p_opportunistic_1p1c.py that looked at 1p1c
packages from different peers. Instead of checking that the right peer
is punished, we now check that the package is not submitted. We can't
use the functional test to see that the package was not considered
because the behavior is indistinguishable (except for the logs).
merge-script