A bridge connects two blockchains: a locking chain and an issuing
chain (also called a mainchain and a sidechain). Both are independent
ledgers, with their own validators and potentially their own custom
transactions. Importantly, there is a way to move assets from the
locking chain to the issuing chain and a way to return those assets from
the issuing chain back to the locking chain: the bridge. This key
operation is called a cross-chain transfer. A cross-chain transfer is
not a single transaction. It happens on two chains, requires multiple
transactions, and involves an additional server type called a "witness".
A bridge does not exchange assets between two ledgers. Instead, it locks
assets on one ledger (the "locking chain") and represents those assets
with wrapped assets on another chain (the "issuing chain"). A good model
to keep in mind is a box with an infinite supply of wrapped assets.
Putting an asset from the locking chain into the box will release a
wrapped asset onto the issuing chain. Putting a wrapped asset from the
issuing chain back into the box will release one of the existing locking
chain assets back onto the locking chain. There is no other way to get
assets into or out of the box. Note that there is no way for the box to
"run out of" wrapped assets - it has an infinite supply.
Co-authored-by: Gregory Popovitch <greg7mdp@gmail.com>
Add AMM functionality:
- InstanceCreate
- Deposit
- Withdraw
- Governance
- Auctioning
- payment engine integration
To support this functionality, add:
- New RPC method, `amm_info`, to fetch pool and LPT balances
- AMM Root Account
- trust line for each IOU AMM token
- trust line to track Liquidity Provider Tokens (LPT)
- `ltAMM` object
The `ltAMM` object tracks:
- fee votes
- auction slot bids
- AMM tokens pair
- total outstanding tokens balance
- `AMMID` to AMM `RootAccountID` mapping
Add new classes to facilitate AMM integration into the payment engine.
`BookStep` uses these classes to infer if AMM liquidity can be consumed.
The AMM formula implementation uses the new Number class added in #4192.
IOUAmount and STAmount use Number arithmetic.
Add AMM unit tests for all features.
AMM requires the following amendments:
- featureAMM
- fixUniversalNumber
- featureFlowCross
Notes:
- Current trading fee threshold is 1%
- AMM currency is generated by: 0x03 + 152 bits of sha256{cur1, cur2}
- Current max AMM Offers is 30
---------
Co-authored-by: Howard Hinnant <howard.hinnant@gmail.com>
Curtail the occurrence of order books that are blocked by reduced offers
with the implementation of the fixReducedOffersV1 amendment.
This commit identifies three ways in which offers can be reduced:
1. A new offer can be partially crossed by existing offers, so the new
offer is reduced when placed in the ledger.
2. An in-ledger offer can be partially crossed by a new offer in a
transaction. So the in-ledger offer is reduced by the new offer.
3. An in-ledger offer may be under-funded. In this case the in-ledger
offer is scaled down to match the available funds.
Reduced offers can block order books if the effective quality of the
reduced offer is worse than the quality of the original offer (from the
perspective of the taker). It turns out that, for small values, the
quality of the reduced offer can be significantly affected by the
rounding mode used during scaling computations.
This commit adjusts some rounding modes so that the quality of a reduced
offer is always at least as good (from the taker's perspective) as the
original offer.
The amendment is titled fixReducedOffersV1 because additional ways of
producing reduced offers may come to light. Therefore, there may be a
future need for a V2 amendment.
Add the ability to mark amendments as obsolete. There are some known
amendments that should not be voted for because they are broken (or
similar reasons).
This commit marks four amendments as obsolete:
1. `CryptoConditionsSuite`
2. `NonFungibleTokensV1`
3. `fixNFTokenDirV1`
4. `fixNFTokenNegOffer`
When an amendment is `Obsolete`, voting for the amendment is prevented.
A determined operator can still vote for the amendment by changing the
source, and doing so does not break any protocol rules.
The "feature" command now does not modify the vote for obsolete
amendments.
Before this change, there were two options for an amendment's
`DefaultVote` behavior: yes and no.
After this change, there are three options for an amendment's
`VoteBehavior`: DefaultYes, DefaultNo, and Obsolete.
To be clear, if an obsolete amendment were to (somehow) be activated by
consensus, the server still has the code to process transactions
according to that amendment, and would not be amendment blocked. It
would function the same as if it had been voting "no" on the amendment.
Resolves#4014.
Incorporates review feedback from @scottschurr.
Without the protocol amendment introduced by this commit, an NFT ID can
be reminted in this manner:
1. Alice creates an account and mints an NFT.
2. Alice burns the NFT with an `NFTokenBurn` transaction.
3. Alice deletes her account with an `AccountDelete` transaction.
4. Alice re-creates her account.
5. Alice mints an NFT with an `NFTokenMint` transaction with params:
`NFTokenTaxon` = 0, `Flags` = 9).
This will mint a NFT with the same `NFTokenID` as the one minted in step
1. The params that construct the NFT ID will cause a collision in
`NFTokenID` if their values are equal before and after the remint.
With the `fixNFTokenRemint` amendment, there is a new sequence number
construct which avoids this scenario:
- A new `AccountRoot` field, `FirstNFTSequence`, stays constant over
time.
- This field is set to the current account sequence when the account
issues their first NFT.
- Otherwise, it is not set.
- The sequence of a newly-minted NFT is computed by: `FirstNFTSequence +
MintedNFTokens`.
- `MintedNFTokens` is then incremented by 1 for each mint.
Furthermore, there is a new account deletion restriction:
- An account can only be deleted if `FirstNFTSequence + MintedNFTokens +
256` is less than the current ledger sequence.
- 256 was chosen because it already exists in the current account
deletion constraint.
Without this restriction, an NFT may still be remintable. Example
scenario:
1. Alice's account sequence is at 1.
2. Bob is Alice's authorized minter.
3. Bob mints 500 NFTs for Alice. The NFTs will have sequences 1-501, as
NFT sequence is computed by `FirstNFTokenSequence + MintedNFTokens`).
4. Alice deletes her account at ledger 257 (as required by the existing
`AccountDelete` amendment).
5. Alice re-creates her account at ledger 258.
6. Alice mints an NFT. `FirstNFTokenSequence` initializes to her account
sequence (258), and `MintedNFTokens` initializes as 0. This
newly-minted NFT would have a sequence number of 258, which is a
duplicate of what she issued through authorized minting before she
deleted her account.
---------
Signed-off-by: Shawn Xie <shawnxie920@gmail.com>
* Introduces amendment `XRPFees`
* Convert fee voting and protocol messages to use XRPAmounts
* Includes Validations, Change transactions, the "Fees" ledger object,
and subscription messages
* Improve handling of 0 drop reference fee with TxQ. For use with networks that do not want to require fees
* Note that fee escalation logic is still in place, which may cause the
open ledger fee to rise if the network is busy. 0 drop transactions
will still queue, and fee escalation can be effectively disabled by
modifying the configuration on all nodes
* Change default network reserves to match Mainnet
* Name the new SFields *Drops (not *XRP)
* Reserve SField IDs for Hooks
* Clarify comments explaining the ttFEE transaction field validation
featureDisallowIncoming is a new amendment that would allow users to opt-out of incoming Checks, Payment Channels, NFTokenOffers, and trust lines. This commit includes tests.
Adds four new AccountSet Flags:
1. asfDisallowIncomingNFTOffer
2. asfDisallowIncomingCheck
3. asfDisallowIncomingPayChan
4. asfDisallowIncomingTrustline
It turns out that the feature enabled by the tfTrustLine flag
on an NFTokenMint transaction could be used as a means to
attack the NFToken issuer. Details are in
https://github.com/XRPLF/rippled/issues/4300
The fixRemoveNFTokenAutoTrustLine amendment removes the
ability to set the tfTrustLine flag on an NFTokenMint
transaction.
Closes 4300.
Trustlines must be between two different accounts but two trustlines exist
where an account extends trust to itself. They were created in the early
days, likely because of bugs that have been fixed. The new fixTrustLinesToSelf
amendment will remove those trustlines when it activates.
The XLS-20 implementation contained two bugs that would require the
introduction of amendments. This complicates the adoption of XLS-20
by requiring a staggered amendment activation, first of the two fix
amendments, followed by the `NonFungibleTokensV1` amendment.
After consideration, the consensus among node operators is that the
process should be simplified by the introduction of a new amendment
that, if enabled, would behaves as if the `NonFungibleTokensV1` and
the two fix amendments (`fixNFTokenDirV1` and `fixNFTokenNegOffer`)
were activated at once.
This commit implements this proposal; it does not introduce any new
functionality or additional features, above and beyond that offered
by the existing amendments.
The existing code would, incorrectly, allow negative amounts in offers
for non-fungible tokens. Such offers would be handled very differently
depending on the context: a direct offer would fail with an error code
indicating an internal processing error, whereas brokered offers would
improperly succeed.
This commit introduces the `fixNFTokenNegOffer` amendment that detects
such offers during creation and returns an appropriate error code.
The commit also extends the existing code to allow for buy offers that
contain a `Destination` field, so that a specific broker can be set in
the offer.
o Fixes an off-by-one when determining which NFTokenPage an
NFToken belongs on.
o Improves handling of packed sets of 32 NFTs with
identical low 96-bits.
o Fixes marker handling by the account_nfts RPC command.
o Tightens constraints of NFTokenPage invariant checks.
Adds unit tests to exercise the fixed cases as well as tests
for previously untested functionality.
The amendment increases the maximum sign of an account's signer
list from 8 to 32.
Like all new features, the associated amendment is configured with
a default vote of "no" and server operators will have to vote for
it explicitly if they believe it is useful.
* Only require adding the new feature names in one place. (Also need to
increment a counter, but a check on startup will catch that.)
* Allows rippled to have the code to support a given amendment, but
not vote for it by default. This allows the amendment to be enabled in
a future version without necessarily amendment blocking these older
versions.
* The default vote is carried with the amendment name in the list of
supported amendments.
* The amendment table is constructed with the amendment and default
vote.
The Negative UNL is a feature of the XRP Ledger consensus protocol that
improves liveness (the network's ability to make forward progress) during
a partial outage. Using the Negative UNL, servers adjust their effective
UNLs based on which validators are currently online and operational, so
that a new ledger version can be declared validated even if several trusted
validators are offline.
The Negative UNL has no impact on how the network processes transactions
or what transactions' outcomes are, except that it improves the network's
ability to declare outcomes final during some types of partial outages.
The feature was originally introduced with version **1.6.0** but it was
only possible to manually enable this. If merged, this commit introduces
the amendment associated with the feature so that server operators can
vote on whether to enable this feature.
For more details, please see https://xrpl.org/negative-unl.html
This commit closes#3898.
With this amendment, the CheckCash transaction creates a TrustLine
if needed. The change is modeled after offer crossing. And,
similar to offer crossing, cashing a check allows an account to
exceed its trust line limit.
The existing code that deserialized an STAmount was sub-optimal and performed
poorly. In some rare cases the operation could result in otherwise valid
serialized amounts overflowing during deserialization. This commit will help
detect error conditions more quickly and eliminate the problematic corner cases.
* Use theoretical quality to order the strands
* Do not use strands below the user specified quality limit
* Stop exploring strands (at the current quality iteration) once any strand is non-dry
Support for 'out-of-sequence' transaction execution was introduced
in commit 7724cca384.
The changes in that commit were gated under a feature but there was
no corresponding amendment introduced that would allow the network
to vote on this amendment.
This commit introduces 'TicketBatch' amendment as the amendment
that is associated with the tickets feature. If the amendment is
enabled, it will activate support for tickets.
This commit also removes several workarounds that are no longer
needed in unit tests.
Tickets are a mechanism to allow for the "out-of-order" execution of
transactions on the XRP Ledger.
This commit, if merged, reworks the existing support for tickets and
introduces support for 'ticket batching', completing the feature set
needed for tickets.
The code is gated under the newly-introduced `TicketBatch` amendment
and the `Tickets` amendment, which is not presently active on the
network, is being removed.
The specification for this change can be found at:
https://github.com/xrp-community/standards-drafts/issues/16
This change can help improve the liveness of the network during periods of network
instability, by allowing the network to track which validators are presently not online
and to disregard them for the purposes of quorum calculations.
The amendment was partially complete, included no functional code
and, even if activated, it would result in no changes to transaction
proessing. Despite this, removing the amendment is the prudent course
of action and avoids the possibility of an accidental activation.
If additional cryptoconditions are implemented, they will be each
assigned a new, unique amendment code.
* The amendment ballot counting code contained a minor technical
flaw, caused by the use of integer arithmetic and rounding
semantics, that could allow amendments to reach majority with
slightly less than 80% support. This commit introduces an
amendment which, if enabled, will ensure that activation
requires at least 80% support.
* This commit also introduces a configuration option to adjust
the amendment activation hysteresis. This option is useful on
test networks, but should not be used on the main network as
is a network-wide consensus parameter that should not be
changed on a per-server basis; doing so can result in a
hard-fork.
Fixes#3396
Identifiers for retired amendments should not generally be used
in the codebase.
This commit reduces their visibility down to one translation
unit and marks them as unused and deprecated to prevent
accidental reuse.
This commit introduces the "HardenedValidations" amendment which,
if enabled, allows validators to include additional information in
their validations that can increase the robustness of consensus.
Specifically, the commit introduces a new optional field that can
be set in validation messages can be used to attest to the hash of
the latest ledger that a validator considers to be fully validated.
Additionally, the commit leverages the previously introduced "cookie"
field to improve the robustness of the network by making it possible
for servers to automatically detect accidental misconfiguration which
results in two or more validators using the same validation key.
