zcash-android-wallet-sdk/sdk-lib/src/main/java/cash/z/ecc/android/sdk/Synchronizer.kt

742 lines
31 KiB
Kotlin

package cash.z.ecc.android.sdk
import android.content.Context
import cash.z.ecc.android.sdk.WalletInitMode.ExistingWallet
import cash.z.ecc.android.sdk.WalletInitMode.NewWallet
import cash.z.ecc.android.sdk.WalletInitMode.RestoreWallet
import cash.z.ecc.android.sdk.block.processor.CompactBlockProcessor
import cash.z.ecc.android.sdk.exception.InitializeException
import cash.z.ecc.android.sdk.ext.ZcashSdk
import cash.z.ecc.android.sdk.internal.Derivation
import cash.z.ecc.android.sdk.internal.SaplingParamTool
import cash.z.ecc.android.sdk.internal.Twig
import cash.z.ecc.android.sdk.internal.db.DatabaseCoordinator
import cash.z.ecc.android.sdk.internal.model.ext.toBlockHeight
import cash.z.ecc.android.sdk.model.Account
import cash.z.ecc.android.sdk.model.BlockHeight
import cash.z.ecc.android.sdk.model.PercentDecimal
import cash.z.ecc.android.sdk.model.Proposal
import cash.z.ecc.android.sdk.model.TransactionOverview
import cash.z.ecc.android.sdk.model.TransactionRecipient
import cash.z.ecc.android.sdk.model.TransactionSubmitResult
import cash.z.ecc.android.sdk.model.UnifiedSpendingKey
import cash.z.ecc.android.sdk.model.WalletBalance
import cash.z.ecc.android.sdk.model.Zatoshi
import cash.z.ecc.android.sdk.model.ZcashNetwork
import cash.z.ecc.android.sdk.tool.CheckpointTool
import cash.z.ecc.android.sdk.type.AddressType
import cash.z.ecc.android.sdk.type.ConsensusMatchType
import cash.z.ecc.android.sdk.type.ServerValidation
import co.electriccoin.lightwallet.client.model.LightWalletEndpoint
import co.electriccoin.lightwallet.client.model.Response
import kotlinx.coroutines.flow.Flow
import kotlinx.coroutines.flow.StateFlow
import kotlinx.coroutines.runBlocking
import java.io.Closeable
@Suppress("TooManyFunctions")
interface Synchronizer {
// Status
/**
* The network to which this synchronizer is connected and from which it is processing blocks.
*/
val network: ZcashNetwork
/**
* A flow of values representing the [Status] of this Synchronizer. As the status changes, a new
* value will be emitted by this flow.
*/
val status: Flow<Status>
/**
* A flow of progress values, typically corresponding to this Synchronizer downloading blocks.
* Typically, any non-zero value below `PercentDecimal.ONE_HUNDRED_PERCENT` indicates that progress indicators can
* be shown and a value of `PercentDecimal.ONE_HUNDRED_PERCENT` signals that progress is complete and any progress
* indicators can be hidden.
*/
val progress: Flow<PercentDecimal>
/**
* A flow of processor details, updated every time blocks are processed to include the latest
* block height, blocks downloaded and blocks scanned. Similar to the [progress] flow but with a
* lot more detail.
*/
val processorInfo: Flow<CompactBlockProcessor.ProcessorInfo>
/**
* The latest height observed on the network, which does not necessarily correspond to the
* latest downloaded height or scanned height. Although this is present in [processorInfo], it
* is such a frequently used value that it is convenient to have the real-time value by itself.
*/
val networkHeight: StateFlow<BlockHeight?>
/**
* A stream of balance values for the orchard pool.
*/
val orchardBalances: StateFlow<WalletBalance?>
/**
* A stream of balance values for the sapling pool.
*/
val saplingBalances: StateFlow<WalletBalance?>
/**
* A stream of a balance for the transparent pool.
*/
val transparentBalance: StateFlow<Zatoshi?>
/**
* A flow of all the transactions that are on the blockchain.
*/
val transactions: Flow<List<TransactionOverview>>
//
// Latest Properties
//
/**
* An in-memory reference to the latest height seen on the network.
*/
val latestHeight: BlockHeight?
/**
* An in-memory reference to the best known birthday height, which can change if the first
* transaction has not yet occurred.
*/
val latestBirthdayHeight: BlockHeight?
//
// Operations
//
@Suppress("ktlint:standard:no-consecutive-comments")
/**
* Adds the next available account-level spend authority, given the current set of
* [ZIP 316](https://zips.z.cash/zip-0316) account identifiers known, to the wallet
* database.
*
* The caller should store the byte encoding of the returned spending key in a secure
* fashion. This encoding **MUST NOT** be exposed to users. It is an internal encoding
* that is inherently unstable, and only intended to be passed between the SDK and the
* storage backend. The caller **MUST NOT** allow this encoding to be exported or
* imported.
*
* If `seed` was imported from a backup and this method is being used to restore a
* previous wallet state, you should use this method to add all of the desired
* accounts before scanning the chain from the seed's birthday height.
*
* By convention, wallets should only allow a new account to be generated after funds
* have been received by the currently-available account (in order to enable
* automated account recovery).
*
* @param seed the wallet's seed phrase.
*
* @return the newly created ZIP 316 account identifier, along with the binary
* encoding of the `UnifiedSpendingKey` for the newly created account.
*
* This is not yet ready to be a public API!
* suspend fun createAccount(seed: ByteArray): UnifiedSpendingKey
**/
/**
* Gets the current unified address for the given account.
*
* @param account the account whose address is of interest. Use Account.DEFAULT to get a result for the first
* account.
*
* @return the current unified address for the given account.
*/
suspend fun getUnifiedAddress(account: Account): String
/**
* Gets the legacy Sapling address corresponding to the current unified address for the given account.
*
* @param account the account whose address is of interest. Use Account.DEFAULT to get a result for the first
* account.
*
* @return a legacy Sapling address for the given account.
*/
suspend fun getSaplingAddress(account: Account): String
/**
* Gets the legacy transparent address corresponding to the current unified address for the given account.
*
* @param account the account whose address is of interest. Use Account.DEFAULT to get a result for the first
* account.
*
* @return a legacy transparent address for the given account.
*/
suspend fun getTransparentAddress(account: Account): String
/**
* Creates a proposal for transferring funds to the given recipient.
*
* @param account the account from which to transfer funds.
* @param recipient the recipient's address.
* @param amount the amount of zatoshi to send.
* @param memo the optional memo to include as part of the proposal's transactions.
*
* @return the proposal or an exception
*/
suspend fun proposeTransfer(
account: Account,
recipient: String,
amount: Zatoshi,
memo: String = ""
): Proposal
/**
* Creates a proposal for shielding any transparent funds received by the given account.
*
* @param account the account for which to shield funds.
* @param shieldingThreshold the minimum transparent balance required before a
* proposal will be created.
* @param memo the optional memo to include as part of the proposal's transactions.
* @param transparentReceiver a specific transparent receiver within the account that
* should be the source of transparent funds. Default is
* null which will select whichever of the account's
* transparent receivers has funds to shield.
*
* @return the proposal, or null if the transparent balance that would be shielded is
* zero or below `shieldingThreshold`.
*
* @throws Exception if `transparentReceiver` is null and there are transparent funds
* in more than one of the account's transparent receivers.
*/
suspend fun proposeShielding(
account: Account,
shieldingThreshold: Zatoshi,
memo: String = ZcashSdk.DEFAULT_SHIELD_FUNDS_MEMO_PREFIX,
transparentReceiver: String? = null
): Proposal?
/**
* Creates the transactions in the given proposal.
*
* @param proposal the proposal for which to create transactions.
* @param usk the unified spending key associated with the account for which the
* proposal was created.
*
* @return a flow of result objects for the transactions that were created as part of
* the proposal, indicating whether they were submitted to the network or if
* an error occurred.
*/
suspend fun createProposedTransactions(
proposal: Proposal,
usk: UnifiedSpendingKey
): Flow<TransactionSubmitResult>
/**
* Sends zatoshi.
*
* @param usk the unified spending key associated with the notes that will be spent.
* @param amount the amount of zatoshi to send.
* @param toAddress the recipient's address.
* @param memo the optional memo to include as part of the transaction.
*
* @return a flow of PendingTransaction objects representing changes to the state of the
* transaction. Any time the state changes a new instance will be emitted by this flow. This is
* useful for updating the UI without needing to poll. Of course, polling is always an option
* for any wallet that wants to ignore this return value.
*/
@Deprecated(
message = "Upcoming SDK 2.1 will create multiple transactions at once for some recipients.",
replaceWith =
ReplaceWith(
"createProposedTransactions(proposeTransfer(usk.account, toAddress, amount, memo), usk)"
)
)
suspend fun sendToAddress(
usk: UnifiedSpendingKey,
amount: Zatoshi,
toAddress: String,
memo: String = ""
): Long
@Deprecated(
message = "Upcoming SDK 2.1 will create multiple transactions at once for some recipients.",
replaceWith =
ReplaceWith(
"proposeShielding(usk.account, shieldingThreshold, memo)?.let { createProposedTransactions(it, usk) }"
)
)
suspend fun shieldFunds(
usk: UnifiedSpendingKey,
memo: String = ZcashSdk.DEFAULT_SHIELD_FUNDS_MEMO_PREFIX
): Long
/**
* Returns true when the given address is a valid z-addr. Invalid addresses will throw an
* exception. See valid z-addresses characteristics in related ZIP.
*
* @param address the address to validate.
*
* @return true when the given address is a valid z-addr.
*
* @throws RuntimeException when the address is invalid.
*/
suspend fun isValidShieldedAddr(address: String): Boolean
/**
* Returns true when the given address is a valid t-addr. Invalid addresses will throw an
* exception. See valid t-addresses characteristics in related ZIP.
*
* @param address the address to validate.
*
* @return true when the given address is a valid t-addr.
*
* @throws RuntimeException when the address is invalid.
*/
suspend fun isValidTransparentAddr(address: String): Boolean
/**
* Returns true when the given address is a valid ZIP 316 unified address.
*
* This method is intended for type checking (e.g. form validation). Invalid
* addresses will throw an exception.
*
* @param address the address to validate.
*
* @return true when the given address is a valid unified address.
*
* @throws RuntimeException when the address is invalid.
*/
suspend fun isValidUnifiedAddr(address: String): Boolean
/**
* Validate whether the server and this SDK share the same consensus branch. This is
* particularly important to check around network updates so that any wallet that's connected to
* an incompatible server can surface that information effectively. For the SDK, the consensus
* branch is used when creating transactions as each one needs to target a specific branch. This
* function compares the server's branch id to this SDK's and returns information that helps
* determine whether they match.
*
* @return an instance of [ConsensusMatchType] that is essentially a wrapper for both branch ids
* and provides helper functions for communicating detailed errors to the user.
*/
suspend fun validateConsensusBranch(): ConsensusMatchType
/**
* This function checks whether the provided server endpoint is valid. The validation is based on comparing:
* - network types,
* - sapling activation heights
* - consensus branches
*
* @param endpoint LightWalletEndpoint data to be validated
* @param context Context
*
* @return an instance of [ServerValidation] that provides details about the validation result
*/
suspend fun validateServerEndpoint(
context: Context,
endpoint: LightWalletEndpoint
): ServerValidation
/**
* Validates the given address, returning information about why it is invalid. This is a
* convenience method that combines the behavior of [isValidShieldedAddr],
* [isValidTransparentAddr], and [isValidUnifiedAddr] into one call so that the developer
* doesn't have to worry about handling the exceptions that they throw. Rather, exceptions
* are converted to [AddressType.Invalid] which has a `reason` property describing why it is
* invalid.
*
* @param address the address to validate.
*
* @return an instance of [AddressType] providing validation info regarding the given address.
*/
suspend fun validateAddress(address: String): AddressType
/**
* Download all UTXOs for the given account addresses and store any new ones in the database.
*
* @param account The Account, for which all addresses blocks will be downloaded. Use Account.DEFAULT to get a
* result for the first account.
* @param since The BlockHeight, from which blocks will be downloaded.
*
* @return the number of utxos that were downloaded and added to the UTXO table.
*/
suspend fun refreshUtxos(
account: Account,
since: BlockHeight = network.saplingActivationHeight
): Int?
/**
* Returns the balance that the wallet knows about. This should be called after [refreshUtxos].
*/
suspend fun getTransparentBalance(tAddr: String): Zatoshi
/**
* Returns the safest height to which we can rewind, given a desire to rewind to the height
* provided. Due to how witness incrementing works, a wallet cannot simply rewind to any
* arbitrary height. This handles all that complexity yet remains flexible in the future as
* improvements are made.
*/
suspend fun getNearestRewindHeight(height: BlockHeight): BlockHeight
/**
* Rewinds to the safest height to which we can rewind, given a desire to rewind to the height
* provided. Due to how witness incrementing works, a wallet cannot simply rewind to any
* arbitrary height. This handles all that complexity yet remains flexible in the future as
* improvements are made.
*/
suspend fun rewindToNearestHeight(height: BlockHeight)
/**
* Rewinds to the safest height approximately 14 days backward from the current chain tip. Due to how witness
* incrementing works, a wallet cannot simply rewind to any arbitrary height. This handles all that complexity
* yet remains flexible in the future as improvements are made.
*/
suspend fun quickRewind()
/**
* Returns a stream of memos for a transaction. It works for both received and sent transaction.
*
* Note that this function internally resolves any error which comes, logs it, and then transforms it to an empty
* string.
*
* @param transactionOverview For which the memos will be queried
* @return Flow of memo strings
*/
fun getMemos(transactionOverview: TransactionOverview): Flow<String>
/**
* Returns a list of recipients for a transaction.
*/
fun getRecipients(transactionOverview: TransactionOverview): Flow<TransactionRecipient>
/**
* Checks and provides file path to the existing data database file for the given input parameters or throws
* [InitializeException.MissingDatabaseException] if the database does not exist yet.
*
* Note that it's the caller's responsibility to provide a [network] and [alias] to an existing database. Otherwise
* [InitializeException.MissingDatabaseException] is thrown.
*
* @return Path to the already created data database file, or null in case none exists yet
* @throws [InitializeException.MissingDatabaseException] When the requested database for the given inputs
* does not exist yet.
*/
@Throws(InitializeException.MissingDatabaseException::class)
suspend fun getExistingDataDbFilePath(
context: Context,
network: ZcashNetwork,
alias: String = ZcashSdk.DEFAULT_ALIAS
): String
//
// Error Handling
//
/**
* Gets or sets a global error handler. This is a useful hook for handling unexpected critical
* errors.
*
* @return true when the error has been handled and the Synchronizer should attempt to continue.
* False when the error is unrecoverable and the Synchronizer should [stop].
*/
var onCriticalErrorHandler: ((Throwable?) -> Boolean)?
/**
* An error handler for exceptions during processing. For instance, a block might be missing or
* a reorg may get mishandled or the database may get corrupted.
*
* @return true when the error has been handled and the processor should attempt to continue.
* False when the error is unrecoverable and the processor should [stop].
*/
var onProcessorErrorHandler: ((Throwable?) -> Boolean)?
/**
* An error handler for exceptions while submitting transactions to lightwalletd. For instance,
* a transaction may get rejected because it would be a double-spend or the user might lose
* their cellphone signal.
*
* @return true when the error has been handled and the sender should attempt to resend. False
* when the error is unrecoverable and the sender should [stop].
*/
var onSubmissionErrorHandler: ((Throwable?) -> Boolean)?
/**
* Callback for setup errors that occur prior to processing compact blocks. Can be used to
* override any errors encountered during setup. When this listener is missing then all setup
* errors will result in the synchronizer not starting. This is particularly useful for wallets
* to receive a callback right before the SDK will reject a lightwalletd server because it
* appears not to match.
*
* @return true when the setup error should be ignored and processing should be allowed to
* start. Otherwise, processing will not begin.
*/
var onSetupErrorHandler: ((Throwable?) -> Boolean)?
/**
* A callback to invoke whenever a chain error is encountered. These occur whenever the
* processor detects a missing or non-chain-sequential block (i.e. a reorg). At a minimum, it is
* best to log these errors because they are the most common source of bugs and unexpected
* behavior in wallets, due to the chain data mutating and wallets becoming out of sync.
*/
var onChainErrorHandler: ((BlockHeight, BlockHeight) -> Any)?
/**
* Represents the status of this Synchronizer, which is useful for communicating to the user.
*/
enum class Status {
/**
* Indicates that [stop] has been called on this Synchronizer and it will no longer be used.
*/
STOPPED,
/**
* Indicates that this Synchronizer is disconnected from its lightwalletd server.
* When set, a UI element may want to turn red.
*/
DISCONNECTED,
/**
* Indicates that the Synchronizer is actively syncing new blocks. It goes through these stages internally:
* downloading new blocks, validating these blocks, then scanning them, deleting the temporary persisted block
* files, and enhancing transaction details at the end.
*
* In the downloading stage, the Synchronizer is actively downloading new blocks from the
* server.
*
* In the validating stage, the Synchronizer is actively validating new blocks that were downloaded
* from the server. Blocks need to be verified before they are scanned. This confirms that
* each block is chain-sequential, thereby detecting missing blocks and reorgs.
*
* In the scanning stage, Synchronizer is actively decrypting new blocks that were downloaded
* from the server.
*
* In the deleting stage are all temporary persisted block files removed from the persistence.
*
* In the enhancing stage is the Synchronizer actively enhancing newly scanned blocks with additional
* transaction details, fetched from the server.
*/
SYNCING,
/**
* Indicates that this Synchronizer is fully up to date and ready for all wallet functions.
* When set, a UI element may want to turn green. In this state, the balance can be trusted.
*/
SYNCED
}
companion object {
/**
* Primary method that SDK clients will use to construct a synchronizer.
*
* @param zcashNetwork the network to use.
*
* @param alias A string used to segregate multiple wallets in the filesystem. This implies the string
* should not contain characters unsuitable for the platform's filesystem. The default value is
* generally used unless an SDK client needs to support multiple wallets.
*
* @param lightWalletEndpoint Server endpoint. See [cash.z.ecc.android.sdk.model.defaultForNetwork]. If a
* client wishes to change the server endpoint, the active synchronizer will need to be stopped and a new
* instance created with a new value.
*
* @param seed the wallet's seed phrase. This is required the first time a new wallet is set up. For
* subsequent calls, seed is only needed if [InitializerException.SeedRequired] is thrown.
*
* @param birthday Block height representing the "birthday" of the wallet. When creating a new wallet, see
* [BlockHeight.ofLatestCheckpoint]. When restoring an existing wallet, use block height that was first used
* to create the wallet. If that value is unknown, null is acceptable but will result in longer
* sync times. After sync completes, the birthday can be determined from [Synchronizer.latestBirthdayHeight].
*
* @param walletInitMode a required parameter with one of [WalletInitMode] values. Use
* [WalletInitMode.NewWallet] when starting synchronizer for a newly created wallet. Or use
* [WalletInitMode.RestoreWallet] when restoring an existing wallet that was created at some point in the
* past. Or use the last [WalletInitMode.ExistingWallet] type for a wallet which is already initialized
* and needs follow-up block synchronization.
*
* @throws InitializerException.SeedRequired Indicates clients need to call this method again, providing the
* seed bytes.
*
* @throws IllegalStateException If multiple instances of synchronizer with the same network+alias are
* active at the same time. Call `close` to finish one synchronizer before starting another one with the same
* network+alias.
*
* If customized initialization is required (e.g. for dependency injection or testing), see
* [DefaultSynchronizerFactory].
*/
@Suppress("LongParameterList", "LongMethod")
suspend fun new(
context: Context,
zcashNetwork: ZcashNetwork,
alias: String = ZcashSdk.DEFAULT_ALIAS,
lightWalletEndpoint: LightWalletEndpoint,
seed: ByteArray?,
birthday: BlockHeight?,
walletInitMode: WalletInitMode
): CloseableSynchronizer {
val applicationContext = context.applicationContext
validateAlias(alias)
val saplingParamTool = SaplingParamTool.new(applicationContext)
val loadedCheckpoint =
CheckpointTool.loadNearest(
applicationContext,
zcashNetwork,
birthday ?: zcashNetwork.saplingActivationHeight
)
val coordinator = DatabaseCoordinator.getInstance(context)
// The pending transaction database no longer exists, so we can delete the file
coordinator.deletePendingTransactionDatabase(zcashNetwork, alias)
val backend =
DefaultSynchronizerFactory.defaultBackend(
zcashNetwork,
alias,
saplingParamTool,
coordinator
)
val blockStore =
DefaultSynchronizerFactory
.defaultCompactBlockRepository(coordinator.fsBlockDbRoot(zcashNetwork, alias), backend)
val service = DefaultSynchronizerFactory.defaultService(applicationContext, lightWalletEndpoint)
val downloader = DefaultSynchronizerFactory.defaultDownloader(service, blockStore)
val chainTip =
when (walletInitMode) {
is WalletInitMode.RestoreWallet -> {
when (val response = downloader.getLatestBlockHeight()) {
is Response.Success -> {
Twig.info { "Chain tip for recovery until param fetched: ${response.result.value}" }
runCatching { response.result.toBlockHeight(zcashNetwork) }.getOrNull()
}
is Response.Failure -> {
Twig.error {
"Chain tip fetch for recovery until failed with: ${response.toThrowable()}"
}
null
}
}
}
else -> {
null
}
}
val repository =
DefaultSynchronizerFactory.defaultDerivedDataRepository(
context = applicationContext,
rustBackend = backend,
databaseFile = coordinator.dataDbFile(zcashNetwork, alias),
zcashNetwork = zcashNetwork,
checkpoint = loadedCheckpoint,
seed = seed,
numberOfAccounts = Derivation.DEFAULT_NUMBER_OF_ACCOUNTS,
recoverUntil = chainTip,
)
val encoder = DefaultSynchronizerFactory.defaultEncoder(backend, saplingParamTool, repository)
val txManager =
DefaultSynchronizerFactory.defaultTxManager(
encoder,
service
)
val processor =
DefaultSynchronizerFactory.defaultProcessor(
backend = backend,
downloader = downloader,
repository = repository,
birthdayHeight = birthday ?: zcashNetwork.saplingActivationHeight
)
return SdkSynchronizer.new(
zcashNetwork = zcashNetwork,
alias = alias,
repository = repository,
txManager = txManager,
processor = processor,
backend = backend
)
}
/**
* Effectively the same as [new] although designed to be a blocking call with better
* interoperability with Java clients.
*
* This is a blocking call, so it should not be called from the main thread.
*/
@JvmStatic
@Suppress("LongParameterList")
fun newBlocking(
context: Context,
zcashNetwork: ZcashNetwork,
alias: String = ZcashSdk.DEFAULT_ALIAS,
lightWalletEndpoint: LightWalletEndpoint,
seed: ByteArray?,
birthday: BlockHeight?,
walletInitMode: WalletInitMode
): CloseableSynchronizer =
runBlocking {
new(context, zcashNetwork, alias, lightWalletEndpoint, seed, birthday, walletInitMode)
}
/**
* Delete the databases associated with this wallet. This removes all compact blocks and
* data derived from those blocks. Although most data can be regenerated by setting up a new
* Synchronizer instance with the seed, there are two special cases where data is not retained:
* 1. Outputs created with a `null` OVK
* 2. The UA to which a transaction was sent (recovery from seed will only reveal the receiver, not the full UA)
*
* @param appContext the application context.
* @param network the network associated with the data to be erased.
* @param alias the alias used to create the local data.
*
* @return true when one of the associated files was found. False most likely indicates
* that the wrong alias was provided.
*/
suspend fun erase(
appContext: Context,
network: ZcashNetwork,
alias: String = ZcashSdk.DEFAULT_ALIAS
): Boolean = SdkSynchronizer.erase(appContext, network, alias)
}
}
/**
* Sealed class describing wallet initialization mode.
*
* Use [NewWallet] type if the seed was just created as part of a
* new wallet initialization.
*
* Use [RestoreWallet] type if an existed wallet is initialized
* from a restored seed with older birthday height.
*
* Use [ExistingWallet] type if the wallet is already initialized.
*/
sealed class WalletInitMode {
data object NewWallet : WalletInitMode()
data object RestoreWallet : WalletInitMode()
data object ExistingWallet : WalletInitMode()
}
interface CloseableSynchronizer : Synchronizer, Closeable
/**
* Validate that the alias doesn't contain malicious characters by enforcing simple rules which
* permit the alias to be used as part of a file name for the preferences and databases. This
* enables multiple wallets to exist on one device, which is also helpful for sweeping funds.
*
* @param alias the alias to validate.
*
* @throws IllegalArgumentException whenever the alias is not less than 100 characters or
* contains something other than alphanumeric characters. Underscores and hyphens are allowed.
*/
private fun validateAlias(alias: String) {
require(
alias.length in ZcashSdk.ALIAS_MIN_LENGTH..ZcashSdk.ALIAS_MAX_LENGTH &&
alias.all { it.isLetterOrDigit() || it == '_' || it == '-' }
) {
"ERROR: Invalid alias ($alias). For security, the alias must be shorter than 100 " +
"characters and only contain letters, digits, hyphens, and underscores."
}
}