JSON-RPC method idea: list transactions newer than a given txid

+1

I haven't got my hands dirty there yet, and would rather spend what time I find to do import/export of keys, but that is something that would help some of my scripts a lot.

Surely since the WalletTx are added sequentially to the wallet, we can assume that older txid's appear earlier in the wallet?

Then it's simply trivial to do a linear lookup and then continue on spitting out the txid's after that one.

Can anyone confirm this?

The wallet is a key/value db4 database (and a key/value map in RAM).

Neither data structure is ordered by time.

At some point, a website or person accepting a transaction must take this risk.  It is unavoidable, whether you use listreceivedbyaddress or listtransactions.  This is why listtransactions reluctance seems so unusual.

Almost every exchange or website accepting bitcoins achieves a binary decisionpoint, where the transaction is accepted, and goods are shipped or money is exchanged.  After that binary decisionpoint, even if the block chain is reorg'd or transactions disappear, there is nothing the website can do but take a loss (or pursue a refund outside of bitcoin).

From the website's point of view, there is zero effective difference between 'listtransactions 6' and 'listreceivedbyaddress 6', because the end result to the website operator is the same:  the goods have been shipped / order accepted / money exchanged.

I think the important point is that these things are unavoidable unsafe after a certain point, even for listreceivedbyaddress.  So I think it's helpful to compare current website behavior under mainline bitcoin, with listtransactions.   Let us call this the confirmation point.  Addressing your queries...


bitcoinmarket and mtgox and other sites seem to consider 6 confirmations their "confirmation point", the moment at which a transaction may be considered "safe." If a past transaction becomes invalid and disappears, the website cannot avoid potential loss, because the user has already received their PayPal-USD or LR-USD or Pecunix GAU and disappeared.

Same for a web store or brick-and-mortar store.  There is a confirmation point at which the customer receives goods.  If a TX becomes invalid after that, the store takes an unavoidable loss, because the customer is already gone with the purchased goods.


Let us assume that confirmation count for txid 0x1234 is bouncing wildly between 0 to 10 to 0 and back and forth, due to a large number of block reorgs.

Whether it is listreceivedbyaddress or listtransactions, you still have a binary confirmation point, a moment in time, at which the transaction crosses the "approved by store" level of confidence.  At that confirmation point, the customer leaves with purchased goods, and store takes a loss regardless of further block chain or TX behavior.

I do agree a programmer may make a mistake, and assume that number of confirmations will always increase.  But that human mistake, too, will cause danger when used with listreceivedbyaddress.


On this point, I agree that listtransactions presents some additional danger here, due to changing txid, if and only if the new double-spend matches destination bitcoin address being sought by the JSON-RPC user.

Nevertheless, in this case too, the user's security rests entirely on their level of confidence:  if the TX is replaced before 6 confirmations, software will likely not notice anything.  If the TX is replaced after 6 confirmations, the customer has already left with purchased goods, and the bitcoin user takes a loss.


This is simply inherent to bitcoin itself.  A block chain reorg might happen after 50 blocks.  But websites do not want to make their users wait 50 blocks before receiving goods.  It is the well-known snack machine problem.  listtransactions does not add anything to this problem, beyond that which is already vulnerable through listreceivedbyaddress.

Transactions can and will be replaced after the binary "confirmation point."  All users of bitcoin must figure this into their business plans, just like they account for credit card chargeback risk or shoplifting risk.

I'm not talking about the normal risk for a given minconf level, I'm talking about additional pitfalls from listtransactions when used this way.

The OP's example of listtransactions <account> [count=10] [txid] seems to imply and it would be very easy for programmers to assume that if they pass in the last txid of the previous call to listtransactions, they will never see the same transaction more than once, which is not the case.  It would be very easy to double-count payments if you don't maintain your own persistent map or dictionary to track which txid's you've already accepted.

It doesn't seem right to have a function that seems tailor made to be used a certain obvious way, and that way is a non-obvious trap.

Suppose both spends are to the same address.  getreceivedbyaddress would always count only one or the other spend at any given time, never both.

Using listtransactions, it would be very easy to count both.  You see the first spend, you count it.  You see the second spend, you count it.  Total is double counted.

I agree with you and satoshi about "txs after <txid>".  My listtransactions (now xlisttransactions) patch pointedly does not have that feature, and never has.

Sure, and that's easy enough to track with transactions.