214 lines
8.4 KiB
Kotlin
214 lines
8.4 KiB
Kotlin
package cash.z.wallet.sdk.transaction
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import cash.z.wallet.sdk.db.entity.EncodedTransaction
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import cash.z.wallet.sdk.exception.TransactionEncoderException
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import cash.z.wallet.sdk.ext.*
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import cash.z.wallet.sdk.jni.RustBackend
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import cash.z.wallet.sdk.jni.RustBackendWelding
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import com.squareup.okhttp.OkHttpClient
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import com.squareup.okhttp.Request
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import kotlinx.coroutines.Dispatchers.IO
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import kotlinx.coroutines.withContext
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import okio.Okio
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import java.io.File
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/**
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* Class responsible for encoding a transaction in a consistent way. This bridges the gap by
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* behaving like a stateless API so that callers can request [createTransaction] and receive a
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* result, even though there are intermediate database interactions.
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*
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* @property rustBackend the instance of RustBackendWelding to use for creating and validating.
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* @property repository the repository that stores information about the transactions being created
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* such as the raw bytes and raw txId.
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*/
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class WalletTransactionEncoder(
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private val rustBackend: RustBackendWelding,
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private val repository: TransactionRepository
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) : TransactionEncoder {
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/**
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* Creates a transaction, throwing an exception whenever things are missing. When the provided
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* wallet implementation doesn't throw an exception, we wrap the issue into a descriptive
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* exception ourselves (rather than using double-bangs for things).
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*
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* @param spendingKey the key associated with the notes that will be spent.
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* @param zatoshi the amount of zatoshi to send.
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* @param toAddress the recipient's address.
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* @param memo the optional memo to include as part of the transaction.
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* @param fromAccountIndex the optional account id to use. By default, the 1st account is used.
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*
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* @return the successfully encoded transaction or an exception
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*/
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override suspend fun createTransaction(
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spendingKey: String,
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zatoshi: Long,
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toAddress: String,
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memo: ByteArray?,
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fromAccountIndex: Int
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): EncodedTransaction = withContext(IO) {
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val transactionId = createSpend(spendingKey, zatoshi, toAddress, memo)
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repository.findEncodedTransactionById(transactionId)
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?: throw TransactionEncoderException.TransactionNotFoundException(transactionId)
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}
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/**
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* Utility function to help with validation. This is not called during [createTransaction]
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* because this class asserts that all validation is done externally by the UI, for now.
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*
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* @param address the address to validate
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*
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* @return true when the given address is a valid z-addr
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*/
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override suspend fun isValidShieldedAddress(address: String): Boolean = withContext(IO) {
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rustBackend.isValidShieldedAddr(address)
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}
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/**
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* Utility function to help with validation. This is not called during [createTransaction]
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* because this class asserts that all validation is done externally by the UI, for now.
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*
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* @param address the address to validate
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*
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* @return true when the given address is a valid t-addr
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*/
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override suspend fun isValidTransparentAddress(address: String): Boolean = withContext(IO) {
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rustBackend.isValidTransparentAddr(address)
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}
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override suspend fun getConsensusBranchId(): Long {
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val height = repository.lastScannedHeight()
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if (height < ZcashSdk.SAPLING_ACTIVATION_HEIGHT)
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throw TransactionEncoderException.IncompleteScanException(height)
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return rustBackend.getBranchIdForHeight(height)
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}
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/**
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* Does the proofs and processing required to create a transaction to spend funds and inserts
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* the result in the database. On average, this call takes over 10 seconds.
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*
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* @param spendingKey the key associated with the notes that will be spent.
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* @param zatoshi the amount of zatoshi to send.
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* @param toAddress the recipient's address.
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* @param memo the optional memo to include as part of the transaction.
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* @param fromAccountIndex the optional account id to use. By default, the 1st account is used.
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*
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* @return the row id in the transactions table that contains the spend transaction or -1 if it
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* failed.
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*/
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private suspend fun createSpend(
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spendingKey: String,
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zatoshi: Long,
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toAddress: String,
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memo: ByteArray? = byteArrayOf(),
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fromAccountIndex: Int = 0
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): Long = withContext(IO) {
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twigTask("creating transaction to spend $zatoshi zatoshi to" +
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" ${toAddress.masked()} with memo $memo") {
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try {
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val branchId = getConsensusBranchId()
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ensureParams((rustBackend as RustBackend).pathParamsDir)
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twig("params exist! attempting to send with consensus branchId $branchId...")
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rustBackend.createToAddress(
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branchId,
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fromAccountIndex,
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spendingKey,
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toAddress,
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zatoshi,
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memo
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)
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} catch (t: Throwable) {
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twig("${t.message}")
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throw t
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}
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}.also { result ->
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twig("result of sendToAddress: $result")
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}
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}
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/**
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* Checks the given directory for the output and spending params and calls [fetchParams] if
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* they're missing.
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*
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* @param destinationDir the directory where the params should be stored.
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*/
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private suspend fun ensureParams(destinationDir: String) {
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var hadError = false
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arrayOf(
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ZcashSdk.SPEND_PARAM_FILE_NAME,
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ZcashSdk.OUTPUT_PARAM_FILE_NAME
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).forEach { paramFileName ->
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if (!File(destinationDir, paramFileName).exists()) {
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twig("ERROR: $paramFileName not found at location: $destinationDir")
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hadError = true
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}
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}
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if (hadError) {
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try {
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Bush.trunk.twigTask("attempting to download missing params") {
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fetchParams(destinationDir)
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}
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} catch (e: Throwable) {
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twig("failed to fetch params due to: $e")
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throw TransactionEncoderException.MissingParamsException
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}
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}
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}
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/**
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* Download and store the params into the given directory.
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*
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* @param destinationDir the directory where the params will be stored. It's assumed that we
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* have write access to this directory. Typically, this should be the app's cache directory
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* because it is not harmful if these files are cleared by the user since they are downloaded
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* on-demand.
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*/
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suspend fun fetchParams(destinationDir: String) = withContext(IO) {
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val client = createHttpClient()
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var failureMessage = ""
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arrayOf(
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ZcashSdk.SPEND_PARAM_FILE_NAME,
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ZcashSdk.OUTPUT_PARAM_FILE_NAME
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).forEach { paramFileName ->
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val url = "${ZcashSdk.CLOUD_PARAM_DIR_URL}/$paramFileName"
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val request = Request.Builder().url(url).build()
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val response = client.newCall(request).execute()
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if (response.isSuccessful) {
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twig("fetch succeeded")
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val file = File(destinationDir, paramFileName)
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if(file.parentFile.exists()) {
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twig("directory exists!")
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} else {
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twig("directory did not exist attempting to make it")
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file.parentFile.mkdirs()
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}
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Okio.buffer(Okio.sink(file)).use {
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twig("writing to $file")
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it.writeAll(response.body().source())
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}
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twig("fetch succeeded, done writing $paramFileName")
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} else {
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failureMessage += "Error while fetching $paramFileName : $response\n"
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twig(failureMessage)
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}
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}
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if (failureMessage.isNotEmpty()) throw TransactionEncoderException.FetchParamsException(failureMessage)
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}
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//
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// Helpers
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//
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/**
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* Http client is only used for downloading sapling spend and output params data, which are
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* necessary for the wallet to scan blocks.
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*
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* @return an http client suitable for downloading params data.
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*/
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private fun createHttpClient(): OkHttpClient {
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//TODO: add logging and timeouts
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return OkHttpClient()
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}
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}
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