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e7a7bb83c1
#5224 added (among other things) a `VaultWithdraw` transaction that allows setting the recipient of the withdrawn funds in the `Destination` transaction field. This technically turns this transaction into a payment, and in some respect the implementation does follow payment rules, e.g. enforcement of `lsfRequireDestTag` or `lsfDepositAuth`, or that MPT transfer has destination `MPToken`. However for IOUs, it missed verification that the destination account has a trust line to the asset issuer. Since the default behavior of `accountSendIOU` is to create this trust line (if missing), this is what `VaultWithdraw` currently does. This is incorrect, since the `Destination` might not be interested in holding the asset in question; this basically enables spammy transfers. This change, therefore, removes automatic creation of a trust line to the `Destination` account in `VaultWithdraw`.
protocol
Classes and functions for handling data and values associated with the XRP Ledger protocol.
Serialized Objects
Objects transmitted over the network must be serialized into a canonical format. The prefix "ST" refers to classes that deal with the serialized format.
The term "Tx" or "tx" is an abbreviation for "Transaction", a commonly occurring object type.
Optional Fields
Our serialized fields have some "type magic" to make optional fields easier to read:
- The operation
x[sfFoo]means "return the value of 'Foo' if it exists, or the default value if it doesn't." - The operation
x[~sfFoo]means "return the value of 'Foo' if it exists, or nothing if it doesn't." This usage of the tilde/bitwise NOT operator is not standard outside of therippledcodebase.- As a consequence of this,
x[~sfFoo] = y[~sfFoo]assigns the value of Foo from y to x, including omitting Foo from x if it doesn't exist in y.
- As a consequence of this,
Typically, for things that are guaranteed to exist, you use
x[sfFoo] and avoid having to deal with a container that may
or may not hold a value. For things not guaranteed to exist,
you use x[~sfFoo] because you want such a container. It
avoids having to look something up twice, once just to see if
it exists and a second time to get/set its value.
(Real example)
The source of this "type magic" is in SField.h.