signrawtransaction incorrectly reports "complete" as false when the transaction is completely signed #5960

I took a random transaction in a random block. When attempting to sign an already signed transaction it should report the "complete" field as "true", in this example it reports false.

Results of a getinfo (txindex is enabled)

{
    "version" : 109900,
    "protocolversion" : 70002,
    "walletversion" : 60000,
    "balance" : 47.88578288,
    "blocks" : 350358,
    "timeoffset" : -1,
    "connections" : 8,
    "proxy" : "",
    "difficulty" : 46717549644.70642090,
    "testnet" : false,
    "keypoololdest" : 1400773375,
    "keypoolsize" : 101,
    "unlocked_until" : 1427969640,
    "paytxfee" : 0.00000000,
    "relayfee" : 0.00001000,
    "errors" : "This is a pre-release test build - use at your own risk - do not use for mining or merchant applications"
}

Reproduction:

$ bitcoin getrawtransaction be273ceb7449ec7c906ce6ee2cf9e8aab15b025235526a5e61cfd3cbabc628ed
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

$ bitcoin signrawtransaction 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
{
    "hex" : "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",
    "complete" : false
}

signrawtransaction uses the standard script verification flags to test the signatures, which are stricter than the consensus rules, and certainly stricter than what the consensus rules were in the past.

@sipa I'm slightly confused by your answer, isn't a transaction being signed purely binary depending on whether the transaction bears a valid signature or not?

If the transaction is checked with isStandard(), wouldn't that mandate second flag, to get an output like

{
    "hex" : "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",
    "complete" : true,
    "standard": false
}

It's a bit more complicated than that. Script validation has several flags, some are controlled by softforks, some by policy. It's not exactly IsStandard(), but similar.

We should probably reduce the flags used to check script completeness to just the mandatory flags.

This is no longer an issue in recent versions of Bitcoin Core. We'll close it for now, please feel free to add additional comments or open a new issue if you think that would be helpful.

Deprecated by PSBT