Latest posts of: dougEfish

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Bitcoin / Bitcoin Technical Support / Calculating WitnessSigOps

on: November 07, 2022, 12:27:08 PM

Bitcoin nodes calculate signature operations for transactions and limit to amount of operations. Currently, max is 80,000 https://github.com/bitcoin/bitcoin/blob/24.x/src/consensus/consensus.h#L16-L17. Presumably, this is to prevent DoS type of attacks . If nodes spend all their time checking sigs, they won't keep up. Function WitnessSigOps https://github.com/bitcoin/bitcoin/blob/24.x/src/script/interpreter.cpp#L2072-L2087 simply checks the size of SegWit v0 data and returns a cost of 1. (See WITNESS_V0_KEYHASH_SIZE https://github.com/bitcoin/bitcoin/blob/24.x/src/script/interpreter.h#L226 ) Is it possible to construct a tx such that bitcoin nodes believe total signature operation costs is low, but in actuality nodes end up wasting CPU cycles and fail to catch up with the tip?

Bitcoin / Development & Technical Discussion / Re: MoneyRange() allows zero?

on: April 13, 2022, 11:13:49 AM

in tx_check.cpp

Code:

// Check for negative or overflow output values (see CVE-2010-5139)
CAmount nValueOut = 0;
for (const auto& txout : tx.vout)
{
     if (txout.nValue < 0)
          return state.Invalid(TxValidationResult::TX_CONSENSUS, "bad-txns-vout-negative");
     if (txout.nValue > MAX_MONEY)
          return state.Invalid(TxValidationResult::TX_CONSENSUS, "bad-txns-vout-toolarge");
     nValueOut += txout.nValue;
     if (!MoneyRange(nValueOut))
          return state.Invalid(TxValidationResult::TX_CONSENSUS, "bad-txns-txouttotal-toolarge");
}

It looks like you can

Bitcoin / Development & Technical Discussion / MoneyRange() allows zero?

on: April 13, 2022, 10:45:38 AM

In MoneyRange(): Code: inline bool MoneyRange(const CAmount& nValue) { return (nValue >= 0 && nValue <= MAX_MONEY); } Zero is valid. I can see how fees can be zero, but is it possible for CAmount in a transaction (e.g. p2wh address1 --> address2) be zero?

Bitcoin / Development & Technical Discussion / Re: BCLog::Bench - Timing nothing of value

on: September 23, 2021, 08:51:36 AM

Thanks PR https://github.com/bitcoin/bitcoin/pull/23072 Issue https://github.com/bitcoin/bitcoin/issues/23071

Bitcoin / Development & Technical Discussion / BCLog::Bench - Timing nothing of value

on: September 22, 2021, 02:44:28 PM

I recently setup up a new node and was perplexed why processing the chain took longer than expected. I'm downloading from another node on my local gigabit network, so bandwidth wasn't my bottleneck. I saw a -debug flag with a bench property, so I enabled this setting. Long story short, the disk I used was really slow. Anyways, I came across some code that doesn't seem to time anything of value: Code: int64_t nTime5 = GetTimeMicros(); nTimeIndex += nTime5 - nTime4; LogPrint(BCLog::BENCH, " - Index writing: %.2fms [%.2fs (%.2fms/blk)]\n", MILLI * (nTime5 - nTime4), nTimeIndex * MICRO, nTimeIndex * MILLI / nBlocksTotal); int64_t nTime6 = GetTimeMicros(); nTimeCallbacks += nTime6 - nTime5; LogPrint(BCLog::BENCH, " - Callbacks: %.2fms [%.2fs (%.2fms/blk)]\n", MILLI * (nTime6 - nTime5), nTimeCallbacks * MICRO, nTimeCallbacks * MILLI / nBlocksTotal); This is in https://github.com/bitcoin/bitcoin/blob/master/src/validation.cpp#L1873 Correct if I'm wrong, but it seems "Callbacks" is timing the execution of the "Index writing" LogPrintf along with some basic computations (nTime6 - nTime5) Inspection of my debug.log indicates a consistent time of around ~20-30 microseconds. Is this timing anything of value? Callbacks bench was added (I think) in this commit: https://github.com/bitcoin/bitcoin/commit/d70bc52ee31b8c4c87ee011625e7031c2dc89c0c If this is dead (legacy) code, I'll open merge request and remove it. Could someone confirm ? Thanks.

Bitcoin / Development & Technical Discussion / Re: Metrics in Bitcoin Core with Opentelemetry

on: May 08, 2021, 07:16:46 PM

My intent is not to integrate this into Core, but to fork Core so that: 1. I learn about the bitcoin software architecture through metrics 2. integrate an abstract lib that can be configured to export to statsd or prometheus (or even both and others) https://github.com/jlopp/statoshi hard codes statsd, I personally want prometheus. Opentelemetry-cpp seems to be flexible in collecting metrics. I'm wondering if opentelemetry-cpp is stable and worth it...or maybe there's another way.

Bitcoin / Development & Technical Discussion / Metrics in Bitcoin Core with Opentelemetry

on: May 08, 2021, 04:28:13 PM

jlopp has a great fork for node metrics https://github.com/jlopp/statoshi and I'll like to extend it. Currently statoshi only exports metrics to statsd but I want to the ability to write (easily) to another collector. Opentelemetry ( https://github.com/open-telemetry/opentelemetry-cpp ) is one lib I found that provides an abstract interface and already has multiple collectors (e.g. https://github.com/open-o11y/docs/tree/master/cpp-prometheus) Thoughts on this approach? Is there another lib or methodology that makes more sense?

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