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Merged in rnicoll-cash-common (pull request #75)

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Refactor verification of cash contract
This commit is contained in:
Ross Nicoll 2016-05-05 11:14:46 +01:00
commit a5b5ceeb9b
2 changed files with 46 additions and 30 deletions
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59
contracts/src/main/kotlin/contracts/Cash.kt
View File

@ -93,28 +93,7 @@ class Cash : Contract {
"there are no zero sized outputs" by outputs.none { it.amount.pennies == 0L }
}
val issueCommand = tx.commands.select<Commands.Issue>().singleOrNull()
if (issueCommand != null && outputs.isNotEmpty()) {
// If we have an issue command, perform special processing: the group is allowed to have no inputs,
// and the output states must have a deposit reference owned by the signer.
//
// Whilst the transaction *may* have no inputs, it can have them, and in this case the outputs must
// sum to more than the inputs. An issuance of zero size is not allowed.
//
// Note that this means literally anyone with access to the network can issue cash claims of arbitrary
// amounts! It is up to the recipient to decide if the backing party is trustworthy or not, via some
// as-yet-unwritten identity service. See ADP-22 for discussion.
// The grouping ensures that all outputs have the same deposit reference and currency.
val inputAmount = inputs.sumCashOrZero(currency)
val outputAmount = outputs.sumCash()
requireThat {
"the issue command has a nonce" by (issueCommand.value.nonce != 0L)
"output deposits are owned by a command signer" by (issuer in issueCommand.signingParties)
"output values sum to more than the inputs" by (outputAmount > inputAmount)
}
continue
}
if (verifyIssueCommands(inputs, outputs, tx, currency, issuer)) continue
val inputAmount = inputs.sumCashOrNull() ?: throw IllegalArgumentException("there is at least one cash input for this group")
val outputAmount = outputs.sumCashOrZero(currency)
@ -130,17 +109,37 @@ class Cash : Contract {
(inputAmount == outputAmount + amountExitingLedger)
}
// Now check the digital signatures on the move command. Every input has an owning public key, and we must
// see a signature from each of those keys. The actual signatures have been verified against the transaction
// data by the platform before execution.
val owningPubKeys = inputs.map { it.owner }.toSet()
val keysThatSigned = tx.commands.requireSingleCommand<Commands.Move>().signers.toSet()
requireThat {
"the owning keys are the same as the signing keys" by keysThatSigned.containsAll(owningPubKeys)
}
verifyMoveCommands<Commands.Move>(inputs, tx)
}
}
private fun verifyIssueCommands(inputs: List<State>, outputs: List<State>, tx: TransactionForVerification, currency: Currency, issuer: Party): Boolean {
val issueCommand = tx.commands.select<Commands.Issue>().singleOrNull()
if (issueCommand == null || outputs.isEmpty()) {
return false
}
// If we have an issue command, perform special processing: the group is allowed to have no inputs,
// and the output states must have a deposit reference owned by the signer.
//
// Whilst the transaction *may* have no inputs, it can have them, and in this case the outputs must
// sum to more than the inputs. An issuance of zero size is not allowed.
//
// Note that this means literally anyone with access to the network can issue cash claims of arbitrary
// amounts! It is up to the recipient to decide if the backing party is trustworthy or not, via some
// as-yet-unwritten identity service. See ADP-22 for discussion.
// The grouping ensures that all outputs have the same deposit reference and currency.
val inputAmount = inputs.sumCashOrZero(currency)
val outputAmount = outputs.sumCash()
requireThat {
"the issue command has a nonce" by (issueCommand.value.nonce != 0L)
"output deposits are owned by a command signer" by (issuer in issueCommand.signingParties)
"output values sum to more than the inputs" by (outputAmount > inputAmount)
}
return true
}
/**
* Puts together an issuance transaction for the specified amount that starts out being owned by the given pubkey.
*/

17
core/src/main/kotlin/core/ContractsDSL.kt
View File

@ -81,3 +81,20 @@ fun List<AuthenticatedObject<CommandData>>.getTimestampByName(vararg names: Stri
return null
}
/**
* Simple functionality for verifying a move command. Verifies that each input has a signature from its owning key.
*
* @param T the type of the move command
*/
@Throws(IllegalArgumentException::class)
// TODO: Can we have a common Move command for all contracts and avoid the reified type parameter here?
inline fun <reified T : CommandData> verifyMoveCommands(inputs: List<OwnableState>, tx: TransactionForVerification) {
// Now check the digital signatures on the move command. Every input has an owning public key, and we must
// see a signature from each of those keys. The actual signatures have been verified against the transaction
// data by the platform before execution.
val owningPubKeys = inputs.map { it.owner }.toSet()
val keysThatSigned = tx.commands.requireSingleCommand<T>().signers.toSet()
requireThat {
"the owning keys are the same as the signing keys" by keysThatSigned.containsAll(owningPubKeys)
}
}