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fix solo machine proof height sequence mismatch in connection handshake verification #570

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merged 3 commits into from
May 11, 2021

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colin-axner
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ref: #562

Addresses one problem outlined in the issue above. Enforces that the proof height is equivalent to the current client state sequence.
NOTE: VerifyClientState is missing from ICS 03-connection as noted in #525. It is assumed that it will be inserted after VerifyConnection and before VerifyClientConsensusState

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We should explain the height + 2 bit

Comment on lines +210 to +213
// ICS 003 will not increment the proof height after connection or client state verification
// the solo machine client must increment the proof height by 2 to ensure it matches
// the expected sequence used in the signature
abortTransactionUnless(height + 2 == clientState.consensusState.sequence)
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Is verify client consensus state always going to be called after 2 previous signature checks? It seems weird to hard code this delta in the verification function itself.

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@colin-axner colin-axner May 7, 2021

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Did you see the discussion in #562? I agree it is strange to hard code the delta in the verify function and that we cannot guarantee client consensus state verification will always occur in this order , but I don't see a more elegant solution. The proof height incrementing for each verification call is unique to the solo machine and thus cannot be brought into core IBC. Non-unique sequences is misbehaviour for the solo machine. Proof height may be meaningful to core IBC now or later and thus needs to be verified

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ACK

@cwgoes cwgoes merged commit d4e7af6 into master May 11, 2021
@cwgoes cwgoes deleted the colin/562-sm-sequence-fixes branch May 11, 2021 21:01
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cwgoes commented May 11, 2021

(merging with requisite 2/3 quorum from IBC spec committee)

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3 participants