[#398] Make WalletBirthday an internal type (#414)

This commit makes Renames `WalletBirthday` to `Checkpoint` and
makes Checkpoint an internal type. Public ocurrences of this
type is replaced by `BlockHeight` (Int) and then retrieval of the
Checkpoint is deferred to the appropiate place in the code

Add an extension method to `BlockHeight` to get latest checkpoint
height present in the SDK's bundle

PR Suggestions:

Add test for integer overflow on JSON
File renamed from WalletBirthday to Checkpoint

Sources/ZcashLightClientKit/Block/Processor/CompactBlockProcessor.swift

@@ -403,7 +403,10 @@ public class CompactBlockProcessor {
             config: Configuration(
                 cacheDb: initializer.cacheDbURL,
                 dataDb: initializer.dataDbURL,
-                walletBirthday: initializer.walletBirthday.height,
+                walletBirthday: Checkpoint.birthday(
+                    with: initializer.walletBirthday,
+                    network: initializer.network
+                ).height,
                 network: initializer.network
             ),
             repository: initializer.transactionRepository,

Sources/ZcashLightClientKit/Constants/Checkpoint+Constants.swift

@@ -7,8 +7,8 @@
 
 import Foundation
 
-public extension WalletBirthday {
+extension Checkpoint {
-    static func birthday(with height: BlockHeight, network: ZcashNetwork) -> WalletBirthday {
+    static func birthday(with height: BlockHeight, network: ZcashNetwork) -> Checkpoint {
         let checkpointDirectoryURL = BundleCheckpointURLProvider.default.url(network.networkType)
 
         switch network.networkType {
@@ -20,8 +20,8 @@ public extension WalletBirthday {
     }
 }
 
-extension WalletBirthday {
+extension Checkpoint {
-    static func birthday(with height: BlockHeight, checkpointDirectory: URL) -> WalletBirthday? {
+    static func birthday(with height: BlockHeight, checkpointDirectory: URL) -> Checkpoint? {
         return bestCheckpointHeight(for: height, checkpointDirectory: checkpointDirectory)
             .flatMap { checkpoint(height: $0, directory: checkpointDirectory) }
     }
@@ -44,7 +44,7 @@ extension WalletBirthday {
             .last
     }
 
-    private static func checkpoint(height: BlockHeight, directory checkpointDirectory: URL) -> WalletBirthday? {
+    private static func checkpoint(height: BlockHeight, directory checkpointDirectory: URL) -> Checkpoint? {
         let url = checkpointDirectory
             .appendingPathComponent(String(height))
             .appendingPathExtension("json")
@@ -52,9 +52,9 @@ extension WalletBirthday {
         return try? checkpoint(at: url)
     }
 
-    private static func checkpoint(at url: URL) throws -> WalletBirthday {
+    private static func checkpoint(at url: URL) throws -> Checkpoint {
         let data = try Data(contentsOf: url)
-        let checkpoint = try JSONDecoder().decode(WalletBirthday.self, from: data)
+        let checkpoint = try JSONDecoder().decode(Checkpoint.self, from: data)
         return checkpoint
     }
 }
@@ -79,9 +79,9 @@ extension BundleCheckpointURLProvider {
     static var iOS = BundleCheckpointURLProvider(url: { networkType in
         switch networkType {
         case .mainnet:
-            return WalletBirthday.mainnetCheckpointDirectory
+            return Checkpoint.mainnetCheckpointDirectory
         case .testnet:
-            return WalletBirthday.testnetCheckpointDirectory
+            return Checkpoint.testnetCheckpointDirectory
         }
     })
 
@@ -99,7 +99,7 @@ extension BundleCheckpointURLProvider {
                 subdirectory: "checkpoints/mainnet/",
                 localization: nil
             )?
-            .deletingLastPathComponent() ?? WalletBirthday.mainnetCheckpointDirectory
+            .deletingLastPathComponent() ?? Checkpoint.mainnetCheckpointDirectory
         case .testnet:
            return Bundle.module.url(
                 forResource: "280000",
@@ -107,7 +107,7 @@ extension BundleCheckpointURLProvider {
                 subdirectory: "checkpoints/testnet/",
                 localization: nil
             )?
-            .deletingLastPathComponent() ?? WalletBirthday.testnetCheckpointDirectory
+            .deletingLastPathComponent() ?? Checkpoint.testnetCheckpointDirectory
         }
     })
 }

Sources/ZcashLightClientKit/Constants/Checkpoint+mainnet.swift

@@ -6,8 +6,8 @@
 //
 import Foundation
 
-extension WalletBirthday {
+extension Checkpoint {
-    static let mainnetMin = WalletBirthday(
+    static let mainnetMin = Checkpoint(
         height: 419_200,
         hash: "00000000025a57200d898ac7f21e26bf29028bbe96ec46e05b2c17cc9db9e4f3",
         time: 1540779337,

Sources/ZcashLightClientKit/Constants/Checkpoint+testnet.swift

@@ -7,8 +7,8 @@
 
 import Foundation
 
-extension WalletBirthday {
+extension Checkpoint {
-  static let testnetMin = WalletBirthday(
+  static let testnetMin = Checkpoint(
     height: 280000,
     hash: "000420e7fcc3a49d729479fb0b560dd7b8617b178a08e9e389620a9d1dd6361a",
     time: 1535262293,
@@ -16,5 +16,4 @@ extension WalletBirthday {
   )
   
   static let testnetCheckpointDirectory = Bundle.module.bundleURL.appendingPathComponent("checkpoints/testnet/")
-  
 }

Sources/ZcashLightClientKit/Initializer.swift

@@ -78,7 +78,7 @@ public class Initializer {
     private(set) var downloader: CompactBlockDownloader
     private(set) var network: ZcashNetwork
     private(set) public var viewingKeys: [UnifiedViewingKey]
-    private(set) public var walletBirthday: WalletBirthday
+    private(set) public var walletBirthday: BlockHeight
 
     /**
     Constructs the Initializer
@@ -168,7 +168,7 @@ public class Initializer {
         self.storage = storage
         self.downloader = CompactBlockDownloader(service: service, storage: storage)
         self.viewingKeys = viewingKeys
-        self.walletBirthday = WalletBirthday.birthday(with: walletBirthday, network: network)
+        self.walletBirthday = walletBirthday
         self.network = network
     }
     
@@ -202,12 +202,13 @@ public class Initializer {
         }
     
         do {
+            let checkpoint = Checkpoint.birthday(with: self.walletBirthday, network: network)
             try rustBackend.initBlocksTable(
                 dbData: dataDbURL,
-                height: Int32(walletBirthday.height),
+                height: Int32(checkpoint.height),
-                hash: walletBirthday.hash,
+                hash: checkpoint.hash,
-                time: walletBirthday.time,
+                time: checkpoint.time,
-                saplingTree: walletBirthday.saplingTree,
+                saplingTree: checkpoint.saplingTree,
                 networkType: network.networkType
             )
         } catch RustWeldingError.dataDbNotEmpty {
@@ -216,9 +217,9 @@ public class Initializer {
             throw InitializerError.dataDbInitFailed
         }
         
-        let lastDownloaded = (try? downloader.storage.latestHeight()) ?? walletBirthday.height
+        let lastDownloaded = (try? downloader.storage.latestHeight()) ?? walletBirthday
         // resume from last downloaded block
-        lowerBoundHeight = max(walletBirthday.height, lastDownloaded)
+        lowerBoundHeight = max(walletBirthday, lastDownloaded)
  
         do {
             guard try rustBackend.initAccountsTable(

Sources/ZcashLightClientKit/Model/Checkpoint.swift

@@ -0,0 +1,80 @@
+//
+//  Checkpoint.swift
+//  
+//
+//  Created by Francisco Gindre on 7/12/22.
+//
+
+import Foundation
+
+/// Represents the wallet's birthday which can be thought of as a checkpoint at the earliest moment in history where
+/// transactions related to this wallet could exist. Ideally, this would correspond to the latest block height at the
+/// time the wallet key was created. Worst case, the height of Sapling activation could be used (280000).
+///
+/// Knowing a wallet's birthday can significantly reduce the amount of data that it needs to download because none of
+/// the data before that height needs to be scanned for transactions. However, we do need the Sapling tree data in
+/// order to construct valid transactions from that point forward. This birthday contains that tree data, allowing us
+/// to avoid downloading all the compact blocks required in order to generate it.
+///
+/// New wallets can ignore any blocks created before their birthday.
+///
+/// - Parameters:
+///  - height: the height at the time the wallet was born
+///  - hash: the block hash corresponding to the given height
+///  - time: the time the wallet was born, in seconds
+///  - saplingTree: the sapling tree corresponding to the given height. This takes around 15 minutes of processing to generate from scratch because all blocks since activation need to be considered. So when it is calculated in advance it can save the user a lot of time.
+///  - orchardTree: the orchard tree corresponding to the given height. This field is optional since it won't be available prior
+///   to NU5 activation height for the given network.
+struct Checkpoint: Equatable {
+    private(set) var height: BlockHeight
+    private(set) var hash: String
+    private(set) var time: UInt32
+    private(set) var saplingTree: String
+    private(set) var orchardTree: String?
+}
+
+extension Checkpoint: Decodable {
+    public enum CodingKeys: String, CodingKey {
+        case height
+        case hash
+        case time
+        case saplingTree
+        case orchardTree
+    }
+
+    public init(from decoder: Decoder) throws {
+        let container = try decoder.container(keyedBy: CodingKeys.self)
+        self.height = try Self.getHeight(from: container)
+        self.hash = try container.decode(String.self, forKey: .hash)
+        self.time = try container.decode(UInt32.self, forKey: .time)
+        self.saplingTree = try container.decode(String.self, forKey: .saplingTree)
+        self.orchardTree = try container.decodeIfPresent(String.self, forKey: .orchardTree)
+    }
+
+    static func getHeight(from container: KeyedDecodingContainer<CodingKeys>) throws -> Int {
+        guard
+            let heightString = try? container.decode(String.self, forKey: .height),
+            let height = Int(heightString)
+        else {
+            throw DecodingError.typeMismatch(
+                String.self,
+                DecodingError.Context(
+                    codingPath: [CodingKeys.height],
+                    debugDescription: "expected height to be encoded as a string",
+                    underlyingError: nil
+                )
+            )
+        }
+        return height
+    }
+}
+
+public extension BlockHeight {
+    /// Useful when creating a new wallet to reduce sync times.
+    /// - Parameters:
+    ///  - zcashNetwork: Network to use for the block height.
+    /// - Returns: The block height of the newest checkpoint known by the SDK.
+    static func ofLatestCheckpoint(network: ZcashNetwork) -> BlockHeight {
+        Checkpoint.birthday(with: BlockHeight.max, network: network).height
+    }
+}

Sources/ZcashLightClientKit/Model/WalletTypes.swift

@@ -1,89 +1,10 @@
 //
 //  WalletTypes.swift
-//  Pods
+//  
 //
 //  Created by Francisco Gindre on 4/6/21.
 //
 
-
-/// Represents the wallet's birthday which can be thought of as a checkpoint at the earliest moment in history where
-/// transactions related to this wallet could exist. Ideally, this would correspond to the latest block height at the
-/// time the wallet key was created. Worst case, the height of Sapling activation could be used (280000).
-///
-/// Knowing a wallet's birthday can significantly reduce the amount of data that it needs to download because none of
-/// the data before that height needs to be scanned for transactions. However, we do need the Sapling tree data in
-/// order to construct valid transactions from that point forward. This birthday contains that tree data, allowing us
-/// to avoid downloading all the compact blocks required in order to generate it.
-///
-/// New wallets can ignore any blocks created before their birthday.
-///
-/// - Parameters:
-///  - height: the height at the time the wallet was born
-///  - hash: the block hash corresponding to the given height
-///  - time: the time the wallet was born, in seconds
-///  - saplingTree: the sapling tree corresponding to the given height. This takes around 15 minutes of processing to generate from scratch because all blocks since activation need to be considered. So when it is calculated in advance it can save the user a lot of time.
-///  - orchardTree: the orchard tree corresponding to the given height. This field is optional since it won't be available prior
-///   to NU5 activation height for the given network.
-public struct WalletBirthday: Equatable {
-    public private(set) var height: BlockHeight = -1
-    public private(set) var hash: String = ""
-    public private(set) var time: UInt32 = 0
-    public private(set) var saplingTree: String = ""
-    public private(set) var orchardTree: String?
-}
-
-
-extension WalletBirthday: Decodable {
-    //  let height: BlockHeight
-    //  let hash: String
-    //  let time: UInt32
-    //  let saplingTree: String
-    //  let orchardTree: String?
-    //  func walletBirthday() -> WalletBirthday {
-    //    WalletBirthday(
-    //      height: height,
-    //      hash: hash,
-    //      time: time,
-    //      tree: tree
-    //    )
-    //  }
-
-    public enum CodingKeys: String, CodingKey {
-        case height
-        case hash
-        case time
-        case saplingTree
-        case orchardTree
-    }
-
-    public init(from decoder: Decoder) throws {
-        let container = try decoder.container(keyedBy: CodingKeys.self)
-        self.height = try Self.getHeight(from: container)
-        self.hash = try container.decode(String.self, forKey: .hash)
-        self.time = try container.decode(UInt32.self, forKey: .time)
-        self.saplingTree = try container.decode(String.self, forKey: .saplingTree)
-        self.orchardTree = try container.decodeIfPresent(String.self, forKey: .orchardTree)
-    }
-
-    static func getHeight(from container: KeyedDecodingContainer<CodingKeys>) throws -> Int {
-        guard
-            let heightString = try? container.decode(String.self, forKey: .height),
-            let height = Int(heightString)
-        else {
-            throw DecodingError.typeMismatch(
-                String.self,
-                DecodingError.Context(
-                    codingPath: [CodingKeys.height],
-                    debugDescription: "expected height to be encoded as a string",
-                    underlyingError: nil
-                )
-            )
-        }
-        return height
-    }
-}
-
-
 /**
  Groups a Sapling Extended Full Viewing Key an a tranparent address extended public key.
  */

Sources/ZcashLightClientKit/Synchronizer/SDKSynchronizer.swift

@@ -137,7 +137,7 @@ public class SDKSynchronizer: Synchronizer {
         self.transactionRepository = transactionRepository
         self.utxoRepository = utxoRepository
         self.blockProcessor = blockProcessor
-        self.latestScannedHeight = (try? transactionRepository.lastScannedHeight()) ?? initializer.walletBirthday.height
+        self.latestScannedHeight = (try? transactionRepository.lastScannedHeight()) ?? initializer.walletBirthday
         self.network = initializer.network
         self.subscribeToProcessorNotifications(blockProcessor)
     }
@@ -149,12 +149,12 @@ public class SDKSynchronizer: Synchronizer {
     
     public func initialize() throws {
         try self.initializer.initialize()
-        try self.blockProcessor.setStartHeight(initializer.walletBirthday.height)
+        try self.blockProcessor.setStartHeight(initializer.walletBirthday)
     }
     
     public func prepare() throws {
         try self.initializer.initialize()
-        try self.blockProcessor.setStartHeight(initializer.walletBirthday.height)
+        try self.blockProcessor.setStartHeight(initializer.walletBirthday)
         self.status = .disconnected
     }
 

Tests/DarksideTests/ReOrgTests.swift

@@ -88,7 +88,7 @@ class ReOrgTests: XCTestCase {
         let mockLatestHeight = BlockHeight(663200)
         let targetLatestHeight = BlockHeight(663202)
         let reOrgHeight = BlockHeight(663195)
-        let walletBirthday = WalletBirthday.birthday(with: 663150, network: network).height
+        let walletBirthday = Checkpoint.birthday(with: 663150, network: network).height
         
         try basicReOrgTest(
             baseDataset: .beforeReOrg,
@@ -104,7 +104,7 @@ class ReOrgTests: XCTestCase {
         let mockLatestHeight = BlockHeight(663200)
         let targetLatestHeight = BlockHeight(663250)
         let reOrgHeight = BlockHeight(663180)
-        let walletBirthday = WalletBirthday.birthday(with: BlockHeight(663150), network: network).height
+        let walletBirthday = Checkpoint.birthday(with: BlockHeight(663150), network: network).height
         
         try basicReOrgTest(
             baseDataset: .beforeReOrg,

Tests/DarksideTests/TransactionEnhancementTests.swift

@@ -54,7 +54,7 @@ class TransactionEnhancementTests: XCTestCase {
         
         waitExpectation = XCTestExpectation(description: "\(self.description) waitExpectation")
         
-        let birthday = WalletBirthday.birthday(with: walletBirthday, network: network)
+        let birthday = Checkpoint.birthday(with: walletBirthday, network: network)
         
         let config = CompactBlockProcessor.Configuration.standard(for: self.network, walletBirthday: birthday.height)
         let rustBackend = ZcashRustBackend.self
@@ -125,7 +125,7 @@ class TransactionEnhancementTests: XCTestCase {
     
     func testBasicEnhacement() throws {
         let targetLatestHeight = BlockHeight(663250)
-        let walletBirthday = WalletBirthday.birthday(with: 663151, network: network).height
+        let walletBirthday = Checkpoint.birthday(with: 663151, network: network).height
         
         try basicEnhancementTest(latestHeight: targetLatestHeight, walletBirthday: walletBirthday)
     }

Tests/NetworkTests/BlockScanOperationTests.swift

@@ -24,7 +24,7 @@ class BlockScanOperationTests: XCTestCase {
         extpub: "02075a7f5f7507d64022dad5954849f216b0f1b09b2d588be663d8e7faeb5aaf61"
     )
 
-    var walletBirthDay = WalletBirthday.birthday(
+    var walletBirthDay = Checkpoint.birthday(
         with: 1386000,
         network: ZcashNetworkBuilder.network(for: .testnet)
     )

Tests/OfflineTests/BirthdayTests.swift

@@ -3,12 +3,12 @@ import XCTest
 
 class BirthdayTests: XCTestCase {
     func test_BirthdayGetsMostRecentCheckpointBelowIt_Testnet() throws {
-        let birthday = WalletBirthday.birthday(
+        let birthday = Checkpoint.birthday(
             with: 1530003,
             network: ZcashNetworkBuilder.network(for: .testnet)
         )
 
-        let expected = WalletBirthday(
+        let expected = Checkpoint(
             height: 1530000,
             hash: "0011f78082f26747e02f0ab3525dc34d8df8f69dde273f462fcbf08fe2aa14d6",
             time: 1629030383,
@@ -19,12 +19,12 @@ class BirthdayTests: XCTestCase {
     }
 
     func test_BirthdayGetsMostRecentCheckpointBelowIt_Mainnet() throws {
-        let birthday = WalletBirthday.birthday(
+        let birthday = Checkpoint.birthday(
             with: 1340004,
             network: ZcashNetworkBuilder.network(for: .mainnet)
         )
 
-        let expected = WalletBirthday(
+        let expected = Checkpoint(
             height: 1340000,
             hash: "00000000031bc547da975ebd77d9113b178053f88fb6a1d8511b4f8962c21c4b",
             time: 1627846248,
@@ -35,12 +35,12 @@ class BirthdayTests: XCTestCase {
     }
 
     func test_startBirthdayIsGivenIfTooLow_Testnet() throws {
-        let birthday = WalletBirthday.birthday(
+        let birthday = Checkpoint.birthday(
             with: 4,
             network: ZcashNetworkBuilder.network(for: .testnet)
         )
 
-        let expected = WalletBirthday(
+        let expected = Checkpoint(
             height: 280000,
             hash: "000420e7fcc3a49d729479fb0b560dd7b8617b178a08e9e389620a9d1dd6361a",
             time: 1535262293,
@@ -51,12 +51,12 @@ class BirthdayTests: XCTestCase {
     }
 
     func test_startBirthdayIsGivenIfTooLow_Mainnet() throws {
-        let birthday = WalletBirthday.birthday(
+        let birthday = Checkpoint.birthday(
             with: 4,
             network: ZcashNetworkBuilder.network(for: .mainnet)
         )
 
-        let expected = WalletBirthday(
+        let expected = Checkpoint(
             height: 419200,
             hash: "00000000025a57200d898ac7f21e26bf29028bbe96ec46e05b2c17cc9db9e4f3",
             time: 1540779337,
@@ -69,7 +69,7 @@ class BirthdayTests: XCTestCase {
     func test_orchardTreeIsNotNilOnActivation_Mainnet() throws {
         let activationHeight = 1687104
 
-        let birthday = WalletBirthday.birthday(
+        let birthday = Checkpoint.birthday(
             with: activationHeight,
             network: ZcashNetworkBuilder.network(for: .mainnet)
         )
@@ -81,7 +81,7 @@ class BirthdayTests: XCTestCase {
     func test_orchardTreeIsNilBeforeActivation_Mainnet() throws {
         let activationHeight = 1_687_104
 
-        let birthday = WalletBirthday.birthday(
+        let birthday = Checkpoint.birthday(
             with: activationHeight - 1,
             network: ZcashNetworkBuilder.network(for: .mainnet)
         )
@@ -92,7 +92,7 @@ class BirthdayTests: XCTestCase {
     func test_orchardTreeIsNotNilOnActivation_Testnet() throws {
         let activationHeight = 1_842_420
 
-        let birthday = WalletBirthday.birthday(
+        let birthday = Checkpoint.birthday(
             with: activationHeight,
             network: ZcashNetworkBuilder.network(for: .testnet)
         )
@@ -104,11 +104,31 @@ class BirthdayTests: XCTestCase {
     func test_orchardTreeIsNilBeforeActivation_Testnet() throws {
         let activationHeight = 1687104
 
-        let birthday = WalletBirthday.birthday(
+        let birthday = Checkpoint.birthday(
             with: activationHeight - 1,
             network: ZcashNetworkBuilder.network(for: .testnet)
         )
 
         XCTAssertNil(birthday.orchardTree)
     }
+
+    func test_CheckpointParsingFailsIfIntegerOverflows() throws {
+        let jsonData = Self.integerOverflowJSON.data(using: .utf8)!
+        let decoder = JSONDecoder()
+
+        XCTAssertThrowsError(try decoder.decode(Checkpoint.self, from: jsonData))
+    }
+
+    /// this has height with `Int64.max + 1`
+    static let integerOverflowJSON: String =
+    """
+    {
+      "network": "main",
+      "height": "9223372036854775808",
+      "hash": "0000000000aefe1d3aaa6908bd9fe99d476afd72ec49be60090d6ee48f9272bf",
+      "time": 1656499365,
+      "saplingTree": "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",
+      "orchardTree": "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"
+    }
+    """
 }

Tests/OfflineTests/WalletTests.swift

@@ -57,9 +57,3 @@ class WalletTests: XCTestCase {
 //        XCTAssertNoThrow( try FileManager.default.removeItem(at: cacheData!) )
     }
 }
-
-enum WalletBirthdayProvider {
-    static var testBirthday: WalletBirthday {
-        WalletBirthday()
-    }
-}

Tests/TestUtils/TestCoordinator.swift

@@ -125,7 +125,7 @@ class TestCoordinator {
             outputParamsURL: try __outputParamsURL(),
             spendingKey: spendingKey,
             unifiedViewingKey: unifiedViewingKey,
-            walletBirthday: WalletBirthday.birthday(with: birthday, network: network),
+            walletBirthday: Checkpoint.birthday(with: birthday, network: network),
             network: network,
             loggerProxy: SampleLogger(logLevel: .debug)
         )
@@ -289,7 +289,7 @@ enum TestSynchronizerBuilder {
         outputParamsURL: URL,
         spendingKey: String,
         unifiedViewingKey: UnifiedViewingKey,
-        walletBirthday: WalletBirthday,
+        walletBirthday: Checkpoint,
         network: ZcashNetwork,
         loggerProxy: Logger? = nil
     ) throws -> (spendingKeys: [String]?, synchronizer: SDKSynchronizer) {
@@ -361,7 +361,7 @@ enum TestSynchronizerBuilder {
         spendParamsURL: URL,
         outputParamsURL: URL,
         seedBytes: [UInt8],
-        walletBirthday: WalletBirthday,
+        walletBirthday: Checkpoint,
         network: ZcashNetwork,
         loggerProxy: Logger? = nil
     ) throws -> (spendingKeys: [String]?, synchronizer: SDKSynchronizer) {