Mutli-push op_return

Mutli-push op_return
2017-01-09  3:08 ` Luke Dashjr
  
From: Chris @ 2017-01-09  2:09 UTC (permalink / raw)
  To: Bitcoin Protocol Discussion

Would there be an objection to making op_return outputs with two
pushdatas standard (same max data size)?

Use case is mostly tagging transactions so they can be returned by bloom
filtering nodes:

OP_RETURN <tag> <data>

Since bip37 nodes test each data element in each output script (which I
believe applies to op_return as well?) it provides a lightweight way of
fetching transactions where the tag matches a specific pattern.

It appears a sizable number of nodes/miners already accept such
transactions as this one was mined in the first block...
https://blockchain.info/tx/400b4738f1e4eab4062e085623b9a3a71670f5c0d42e32dbe5a4e71da5baabe0

- Chris





 permalink raw reply	[|nested]
2017-01-09  2:09 [bitcoin-dev] Mutli-push op_return Chris

  2017-01-09  4:32   ` Chris
  
From: Luke Dashjr @ 2017-01-09  3:08 UTC (permalink / raw)
  To: Chris, Bitcoin Protocol Discussion

On Monday, January 09, 2017 2:09:09 AM Chris via bitcoin-dev wrote:
> Would there be an objection to making op_return outputs with two
> pushdatas standard (same max data size)?

Standards (BIPs) need to describe a specific use case and protocol for doing 
it.

As you note, the default policy on most nodes is to allow such outputs.

Luke


 permalink raw reply	[|nested]
2017-01-09  3:08 ` Luke Dashjr

  
From: Chris @ 2017-01-09  4:32 UTC ( / )
  To: Luke Dashjr, Bitcoin Protocol Discussion

Maybe I was too premature. The script wiki (which I realize might not be
up to date) says only one pushdata is allowed but I don't see that in
the code.

https://github.com/bitcoin/bitcoin/blob/e8cfe1ee2d01c493b758a67ad14707dca15792ea/src/policy/policy.cpp#L49

Am I missing something or am I correct to assume that multiple pushdatas
in op_return would normally be considered standard?


On 01/08/2017 10:08 PM, Luke Dashjr wrote:
> On Monday, January 09, 2017 2:09:09 AM Chris via bitcoin-dev wrote:
>> Would there be an objection to making op_return outputs with two
>> pushdatas standard (same max data size)?
> Standards (BIPs) need to describe a specific use case and protocol for doing 
> it.
>
> As you note, the default policy on most nodes is to allow such outputs.
>
> Luke
>