In the event that the pool to which change should be sent cannot
automatically be determined based upon the inputs and outputs of a
transaction, it is up to the caller to specify where change should
be sent.
The existing API limited change outputs to having only a single memo
repeated across each change output. This change makes it so that each
proposed change output can have its own associated memo, and leaves it
up to the input selector to determine how requested change memos are
associated with change outputs.
In order to use `uint64` for amounts that must be nonnegative in the
`proposal.proto` file, it is useful to update fee and change computation
to use `NonNegativeAmount` where possible.
When scanning, a wallet only needs to update balance and transaction
information shown to users when the scan has resulted in a change to
wallet state. This modifies `scan_cached_blocks` to return the range of
block heights actually scanned, along with the counts of notes spent and
received by the wallet in that range.
Fixes#918
This also removes the zcash_client_sqlite-specific database
initialization procedures in favor of a standardized approach using the
methods available via the data access API.
Prior to the scan-before-sync changes, the wallet was able to assume
that the maximum scanned block height at the time of the spend was
within a few blocks of the chain tip. However, under linear scanning
after the spend-before-sync changes this invariant no longer holds,
resulting in a situation where in linear sync conditions the wallet
could attempt to create transactions with already-past expiry heights.
This change separates the notion of "chain tip" from "max scanned
height", relying upon the `scan_queue` table to maintain the wallet's
view of the consensus chain height and using information from the
`blocks` table only in situations where the latest and/or earliest
scanned height is required.
As part of this change, the `WalletRead` interface is also modified to
disambiguate these concepts.
Previously this was not clearly specified, and the implementations in
`zcash_client_sqlite` behaved similarly to when `from_height = None`.
Closeszcash/librustzcash#892.
This implements a priority queue backed by the wallet database for scan
range ordering. The scan queue is updated on each call to `put_blocks`
or to `update_chain_tip`.
In preparation for out-of-order range-based scanning, it is necessary
to ensure that the size of the Sapling note commitment tree is carried
along through the scan process and that stored blocks are always
persisted with the updated note commitment tree size.
Local chain validation will be performed internal to
`scan_cached_blocks`, and as handling of chain reorgs will need to
change to support out-of-order scanning, the `validate_chain` method
will be superfluous. It is removed in advance of other changes in order
to avoid updating it to reflect the forthcoming changes.
This better reflects the semantics of wallet behavior. Also, this
adds a `zcash_client_backend::WalletRead::get_min_unspent_height`
method that replaces the deprecated & removed (and misleadingly
named) `get_rewind_height` method.
Previously, if a caller wanted to use a block source to perform
scanning from the first available block, they would have to guess
at the block height to start from. Changing this to an optional
argument makes this explicit.
This allows callers to validate smaller intervals of the given
`BlockSourceT` shortening processing times of the function call at the
expense of obtaining a partial result on a given section of interest of
the block source.
`params: &ParamsT` has been removed from the arguments since they were
only needed to fall back to `sapling_activation_height` when `None` as
passed as the `validate_from` argument. Passing `None` as validation
start point on a pre-populated `block_source` would result in an error
`ChainError::block_height_discontinuity(sapling_activation_height - 1, current_height)`
With this new API callers must specify a concrete `validate_from`
argument and assume that `validate_chain` will not take any default
fallbacks to chain `ParamsT`.
The addition of a `limit` to the chain validation function changes the
meaning of its successful output, being now a `BlockHeight, BlockHash)`
tuple indicating the block height and block hash up to which the chain
as been validated on its continuity of heights and hashes. Callers
providing a `limit` aregument are responsible of subsequent calls to
`validate_chain()` to complete validating the remaining blocks stored on
the `block_source`.
Closeszcash/librustzcash#705
This adds a set of abstractions that allow wallets to provide
independent strategies for fee estimation and note selection, and
implementations of these strategies that perform these operations in the
same fashion as the existing `spend` and `shield_transparent_funds`
functions.
This required a somewhat hefty rework of the error handling in
zcash_client_backend. It fixes an issue with the error types whereby
callees needed to have a bit too much information about the error
types produced by their callers.
Reflect the updated note selection and error handling in zcash_client_sqlite.
The `MAX` SQLite function returns `null` when the table is empty. The
code was expecting zero rows to be returned in this case, and was trying
to parse the `null` as an integer.
This replaces the current wallet initialization code with a migration
that brings the database up to the state produced by release 0.3.0.
A subsequent commit will add migrations that correctly produce the
database state as of zcash/librustzcash@602270cb1f.
Fixes#369
Per ZIP 316, the Sapling FVK Encoding only includes `(ak, nk, ovk, dk)`
which is a subset of the Sapling `ExtendedFullViewingKey`. We therefore
need to use `DiversifiableFullViewingKey` inside `UnifiedFullViewingKey`
in order to make it parseable from the UFVK string encoding.
`zcash_client_sqlite::wallet::get_extended_full_viewing_keys` has been
removed as a consequence of this change: we can no longer reconstruct
the correct `ExtendedFullViewingKey` from the `UnifiedFullViewingKey`.
Kris Nuttycombe
str4d
Kris Nuttycombe
Francisco Gindre