Output descriptors

CLibWally/module.modulemap

@@ -5,6 +5,7 @@ module CLibWally {
     header "libwally-core/include/wally_bip32.h"
     header "libwally-core/include/wally_bip38.h"
     header "libwally-core/include/wally_bip39.h"
+    header "libwally-core/include/wally_descriptor.h"
     header "libwally-core/include/wally_psbt.h"
     header "libwally-core/include/wally_psbt_members.h"
     header "libwally-core/include/wally_script.h"

LibWally.xcodeproj/project.pbxproj

@@ -25,6 +25,8 @@
 		FE9CD3C0229C397900345DFA /* BIP39Tests.swift in Sources */ = {isa = PBXBuildFile; fileRef = FE9CD3BF229C397900345DFA /* BIP39Tests.swift */; };
 		FEC79CE4229E7F3800D86E2E /* BIP32.swift in Sources */ = {isa = PBXBuildFile; fileRef = FEC79CE3229E7F3800D86E2E /* BIP32.swift */; };
 		FEC79CE6229E807500D86E2E /* BIP32Tests.swift in Sources */ = {isa = PBXBuildFile; fileRef = FEC79CE5229E807500D86E2E /* BIP32Tests.swift */; };
+		A21016BD279EE9D00002330E /* Descriptor.swift in Sources */ = {isa = PBXBuildFile; fileRef = A21016BC279EE9D00002330E /* Descriptor.swift */; };
+		A21016BF279EEFBD0002330E /* DescriptorTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = A21016BE279EEFBD0002330E /* DescriptorTests.swift */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXContainerItemProxy section */
@@ -71,6 +73,8 @@
 		FE9CD3C1229C397900345DFA /* Info.plist */ = {isa = PBXFileReference; lastKnownFileType = text.plist.xml; path = Info.plist; sourceTree = "<group>"; };
 		FEC79CE3229E7F3800D86E2E /* BIP32.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = BIP32.swift; sourceTree = "<group>"; };
 		FEC79CE5229E807500D86E2E /* BIP32Tests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = BIP32Tests.swift; sourceTree = "<group>"; };
+		A21016BC279EE9D00002330E /* Descriptor.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Descriptor.swift; sourceTree = "<group>"; };
+		A21016BE279EEFBD0002330E /* DescriptorTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = DescriptorTests.swift; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
 /* Begin PBXFrameworksBuildPhase section */
@@ -133,6 +137,7 @@
 				FE1A3C0522B395B300EDCB58 /* Address.swift */,
 				FEC79CE3229E7F3800D86E2E /* BIP32.swift */,
 				FE120F54229C3B6900E7720C /* BIP39.swift */,
+				A21016BC279EE9D00002330E /* Descriptor.swift */,
 				A2BCE19323A7D6B200737BEB /* PSBT.swift */,
 				FE8B80A322B3E5630041CC94 /* Script.swift */,
 				A232260022B94A6B00C3B79C /* Transaction.swift */,
@@ -148,6 +153,7 @@
 				FEC79CE5229E807500D86E2E /* BIP32Tests.swift */,
 				FE9CD3BF229C397900345DFA /* BIP39Tests.swift */,
 				FE8B80A122B397090041CC94 /* AddressTests.swift */,
+				A21016BE279EEFBD0002330E /* DescriptorTests.swift */,
 				A2BCE19123A7D28500737BEB /* PSBTTests.swift */,
 				FE8B80A522B3E5760041CC94 /* ScriptTests.swift */,
 				A232260222B94A8400C3B79C /* TransactionTests.swift */,
@@ -281,6 +287,7 @@
 			isa = PBXResourcesBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
+				A21016C1279F03E20002330E /* README.md in Resources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
@@ -300,6 +307,7 @@
 			files = (
 				FE120F55229C3B6900E7720C /* BIP39.swift in Sources */,
 				A2BCE19423A7D6B200737BEB /* PSBT.swift in Sources */,
+				A21016BD279EE9D00002330E /* Descriptor.swift in Sources */,
 				FE39CDFA229DAAF400DD135E /* DataExtension.swift in Sources */,
 				FE1A3C0622B395B300EDCB58 /* Address.swift in Sources */,
 				FE8B80A422B3E5630041CC94 /* Script.swift in Sources */,
@@ -314,6 +322,7 @@
 			files = (
 				FE8B80A222B397090041CC94 /* AddressTests.swift in Sources */,
 				A23509D72398F33E0045D3A5 /* DataExtensionTests.swift in Sources */,
+				A21016BF279EEFBD0002330E /* DescriptorTests.swift in Sources */,
 				FE8B80A622B3E5760041CC94 /* ScriptTests.swift in Sources */,
 				FEC79CE6229E807500D86E2E /* BIP32Tests.swift in Sources */,
 				A2BCE19223A7D28500737BEB /* PSBTTests.swift in Sources */,

LibWally/Descriptor.swift

@@ -0,0 +1,96 @@
+//
+//  Descriptor.swift
+//  Descriptor
+//
+//  Created by Sjors Provoost on 24/01/2022.
+//  Copyright © 2022 Sjors Provoost. Distributed under the MIT software
+//  license, see the accompanying file LICENSE.md
+
+import Foundation
+@_implementationOnly import CLibWally
+
+public enum DescriptorError: Error {
+    case invalid
+    case noAddress // There is no address representation, e.g. pk()
+    case notRanged // No index should be used for getAddress() when called on a non-ranged descriptor
+    case ranged // Index must be used for getAddress() when called on a ranged descriptor
+}
+
+
+public struct Descriptor {
+    // The descriptor string we were initialized with. Not normalized and not fully validated.
+    var wally_descriptor: OpaquePointer?
+    public var network: Network
+    public var canonical: String
+    public var isRanged: Bool
+
+    // The descriptor is not fully validated.
+    public init(_ descriptor: String, _ network: Network) throws {
+        self.network = network
+
+        // Parse descriptor
+        if (wally_descriptor_parse(descriptor, nil, UInt32(network == .mainnet ? WALLY_NETWORK_BITCOIN_MAINNET : WALLY_NETWORK_BITCOIN_TESTNET), UInt32( WALLY_MINISCRIPT_REQUIRE_CHECKSUM), &wally_descriptor) != WALLY_OK) {
+            throw DescriptorError.invalid
+        }
+
+        // Store properties
+        let feature_flags = UnsafeMutablePointer<UInt32>.allocate(capacity: 1)
+        precondition(wally_descriptor_get_features(wally_descriptor, feature_flags) == WALLY_OK)
+        self.isRanged = (feature_flags.pointee & UInt32(WALLY_MS_IS_RANGED)) != 0
+
+        // Canonicalize the descriptor
+        var output: UnsafeMutablePointer<Int8>?
+        defer {
+            wally_free_string(output)
+        }
+        if (wally_descriptor_canonicalize(wally_descriptor, 0, &output) != WALLY_OK) {
+            throw DescriptorError.invalid
+        } else {
+            precondition(output != nil)
+            self.canonical = String(cString: output!)
+        }
+    }
+
+    /* Deinitializers may only be declared within a class or actor.
+    /  I'm unsure if not freeing up the memory is safe. */
+
+    // deinit {
+    //   wally_descriptor_free(self.wally_descriptor)
+    // }
+
+    // May throw if something is wrong with the descriptor.
+    // Will throw if descriptor can't be expressed as an address, e.g. pk().
+    public func getAddress(_ index: UInt32) throws -> Address {
+        if index != 0 && !self.isRanged {
+            throw DescriptorError.notRanged
+        }
+
+        var output: UnsafeMutablePointer<Int8>?
+        defer {
+            wally_free_string(output)
+        }
+
+        let result = wally_descriptor_to_address(self.wally_descriptor, 0, 0, index, UInt32(0), &output)
+
+        if result != WALLY_OK {
+            throw DescriptorError.invalid
+        }
+
+        precondition(output != nil)
+        if let address = Address(String(cString: output!)) {
+            return address
+        } else {
+            // This code is not reached for pk() descriptors, because wally_descriptor_to_address will fail
+            // TODO: catch descriptors that can't be expressed as an address earlier and explictly
+            throw DescriptorError.noAddress
+        }
+    }
+
+    public func getAddress() throws -> Address {
+        if self.isRanged {
+            throw DescriptorError.ranged
+        }
+        return try getAddress(0)
+    }
+
+}

LibWallyTests/DescriptorTests.swift

@@ -0,0 +1,76 @@
+//
+//  DescriptorTests.swift
+//  DescriptorTests
+//
+//  Created by Sjors Provoost on 24/01/2022.
+//  Copyright © 2022 Sjors Provoost. Distributed under the MIT software
+//  license, see the accompanying file LICENSE.md
+
+import XCTest
+@testable import LibWally
+
+class DescriptorTests: XCTestCase {
+
+    override func setUpWithError() throws {
+        // Put setup code here. This method is called before the invocation of each test method in the class.
+    }
+
+    override func tearDownWithError() throws {
+        // Put teardown code here. This method is called after the invocation of each test method in the class.
+    }
+
+    func testChecksum() throws {
+        XCTAssertThrowsError(try Descriptor("pkh([3442193e/0']xpub68Gmy5EdvgibQVfPdqkBBCHxA5htiqg55crXYuXoQRKfDBFA1WEjWgP6LHhwBZeNK1VTsfTFUHCdrfp1bgwQ9xv5ski8PX9rL2dZXvgGDnw/1)", .mainnet)) { error in
+            XCTAssertEqual(error as! DescriptorError, DescriptorError.invalid)
+        }
+
+        XCTAssertNoThrow(try Descriptor("pkh([3442193e/0']xpub68Gmy5EdvgibQVfPdqkBBCHxA5htiqg55crXYuXoQRKfDBFA1WEjWgP6LHhwBZeNK1VTsfTFUHCdrfp1bgwQ9xv5ski8PX9rL2dZXvgGDnw/1)#62cpuxwx", .mainnet))
+
+        XCTAssertThrowsError(try Descriptor("pkh([3442193e/0']xpub68Gmy5EdvgibQVfPdqkBBCHxA5htiqg55crXYuXoQRKfDBFA1WEjWgP6LHhwBZeNK1VTsfTFUHCdrfp1bgwQ9xv5ski8PX9rL2dZXvgGDnw/1)#00000000", .mainnet)) { error in
+            XCTAssertEqual(error as! DescriptorError, DescriptorError.invalid)
+        }
+    }
+
+    func testAddress() throws {
+        let desc = try! Descriptor("pkh([3442193e/0']xpub68Gmy5EdvgibQVfPdqkBBCHxA5htiqg55crXYuXoQRKfDBFA1WEjWgP6LHhwBZeNK1VTsfTFUHCdrfp1bgwQ9xv5ski8PX9rL2dZXvgGDnw/1)#62cpuxwx", .mainnet)
+        XCTAssertEqual(try! desc.getAddress().description, "1JQheacLPdM5ySCkrZkV66G2ApAXe1mqLj")
+    }
+
+    func testAddressFromRange() throws {
+        let desc = try! Descriptor("pkh([3442193e/0']xpub68Gmy5EdvgibQVfPdqkBBCHxA5htiqg55crXYuXoQRKfDBFA1WEjWgP6LHhwBZeNK1VTsfTFUHCdrfp1bgwQ9xv5ski8PX9rL2dZXvgGDnw/*)#p44786lk", .mainnet)
+        XCTAssertEqual(try! desc.getAddress(1).description, "1JQheacLPdM5ySCkrZkV66G2ApAXe1mqLj")
+    }
+
+    func testMatchingNetwork() throws {        
+        XCTAssertThrowsError(try Descriptor("pkh([3442193e/0']xpub68Gmy5EdvgibQVfPdqkBBCHxA5htiqg55crXYuXoQRKfDBFA1WEjWgP6LHhwBZeNK1VTsfTFUHCdrfp1bgwQ9xv5ski8PX9rL2dZXvgGDnw/1)#62cpuxwx", .testnet)) { error in
+            XCTAssertEqual(error as! DescriptorError, DescriptorError.invalid)
+        }
+    }
+
+    func testNonAddressDescriptor() throws {
+        let desc = try! Descriptor("pk([3442193e/0']xpub68Gmy5EdvgibQVfPdqkBBCHxA5htiqg55crXYuXoQRKfDBFA1WEjWgP6LHhwBZeNK1VTsfTFUHCdrfp1bgwQ9xv5ski8PX9rL2dZXvgGDnw/1)#397dme97", .mainnet)
+
+        XCTAssertThrowsError(try desc.getAddress()) { error in
+            // TODO: have it throw noAddress
+            XCTAssertEqual(error as! DescriptorError, DescriptorError.invalid)
+        }
+
+    }
+
+    func testIndexForNonRangedDescriptor() throws {
+        let desc = try! Descriptor("pkh([3442193e/0']xpub68Gmy5EdvgibQVfPdqkBBCHxA5htiqg55crXYuXoQRKfDBFA1WEjWgP6LHhwBZeNK1VTsfTFUHCdrfp1bgwQ9xv5ski8PX9rL2dZXvgGDnw/1)#62cpuxwx", .mainnet)
+
+        XCTAssertThrowsError(try desc.getAddress(2)) { error in
+            XCTAssertEqual(error as! DescriptorError, DescriptorError.notRanged)
+        }
+    }
+
+    func testMissingIndexForRangedDescriptor() throws {
+        let desc = try! Descriptor("pkh([3442193e/0']xpub68Gmy5EdvgibQVfPdqkBBCHxA5htiqg55crXYuXoQRKfDBFA1WEjWgP6LHhwBZeNK1VTsfTFUHCdrfp1bgwQ9xv5ski8PX9rL2dZXvgGDnw/*)#p44786lk", .mainnet)
+
+        XCTAssertThrowsError(try desc.getAddress()) { error in
+            XCTAssertEqual(error as! DescriptorError, DescriptorError.ranged)
+        }
+    }
+
+}

README.md

@@ -3,7 +3,7 @@
 Opinionated Swift wrapper around [LibWally](https://github.com/ElementsProject/libwally-core),
 a collection of useful primitives for cryptocurrency wallets.
 
-Supports a minimal set of features based on v0.8.7. See also [original docs](https://wally.readthedocs.io/en/release_0.8.7).
+Supports a minimal set of features based on v0.8.8. See also [original docs](https://wally.readthedocs.io/en/release_0.8.8).
 
 - [ ] Core Functions
   - [x] base58 encode / decode
@@ -20,6 +20,10 @@ Supports a minimal set of features based on v0.8.7. See also [original docs](htt
   - [ ] Derive scriptPubKey #6 (wishlist)
 - [ ] BIP38 Functions
 - [x] BIP39 Functions
+- [ ] Descriptor functions
+  - [x] Parse and canonicalize
+  - [x] Convert to address
+  - [ ] Convert to scriptPubKey
 - [ ] Script Functions
   - [x] Serialize scriptPubKey
   - [x] Determine scriptPubkey type