From df18fe6080e6abe3f86c85b40cb51b8dfd282632 Mon Sep 17 00:00:00 2001
From: Dimitri Bouniol <dimitribouniol@mochidev.com>
Date: Mon, 25 Mar 2024 06:40:58 -0700
Subject: [PATCH] Refactored integer casting to use built-in functions

---
 .../Ceremonies/Shared/AuthenticatorData.swift |  4 +--
 Sources/WebAuthn/Helpers/ByteCasting.swift    | 16 +++++++++
 Sources/WebAuthn/Helpers/Numbers+Bytes.swift  | 34 -------------------
 3 files changed, 18 insertions(+), 36 deletions(-)
 delete mode 100644 Sources/WebAuthn/Helpers/Numbers+Bytes.swift

diff --git a/Sources/WebAuthn/Ceremonies/Shared/AuthenticatorData.swift b/Sources/WebAuthn/Ceremonies/Shared/AuthenticatorData.swift
index d0f6771..41cc250 100644
--- a/Sources/WebAuthn/Ceremonies/Shared/AuthenticatorData.swift
+++ b/Sources/WebAuthn/Ceremonies/Shared/AuthenticatorData.swift
@@ -36,7 +36,7 @@ extension AuthenticatorData {
 
         let relyingPartyIDHash = Array(bytes[..<32])
         let flags = AuthenticatorFlags(bytes[32])
-        let counter: UInt32 = Data(bytes[33..<37]).toInteger(endian: .big)
+        let counter = UInt32(bigEndianBytes: bytes[33..<37])
 
         var remainingCount = bytes.count - minAuthDataLength
 
@@ -90,7 +90,7 @@ extension AuthenticatorData {
         /// **credentialIdLength** (2): Byte length L of credentialId, 16-bit unsigned big-endian integer. Value MUST be ≤ 1023.
         let idLengthBytes = data[53..<55]  // Length is 2 bytes
         let idLengthData = Data(idLengthBytes)
-        let idLength: UInt16 = idLengthData.toInteger(endian: .big)
+        let idLength = UInt16(bigEndianBytes: idLengthData)
 
         guard idLength <= 1023
         else { throw WebAuthnError.credentialIDTooLong }
diff --git a/Sources/WebAuthn/Helpers/ByteCasting.swift b/Sources/WebAuthn/Helpers/ByteCasting.swift
index 210e7d6..611f02d 100644
--- a/Sources/WebAuthn/Helpers/ByteCasting.swift
+++ b/Sources/WebAuthn/Helpers/ByteCasting.swift
@@ -31,3 +31,19 @@ extension BidirectionalCollection where Element == UInt8 {
         return result
     }
 }
+
+extension FixedWidthInteger {
+    /// Initialize a fixed width integer from a contiguous sequence of Bytes representing a big endian type.
+    /// - Parameter bigEndianBytes: The Bytes to interpret as a big endian integer.
+    @inlinable
+    init(bigEndianBytes: some BidirectionalCollection<UInt8>) {
+        self.init(bigEndian: bigEndianBytes.casting())
+    }
+
+    /// Initialize a fixed width integer from a contiguous sequence of Bytes representing a little endian type.
+    /// - Parameter bigEndianBytes: The Bytes to interpret as a little endian integer.
+    @inlinable
+    init(littleEndianBytes: some BidirectionalCollection<UInt8>) {
+        self.init(littleEndian: littleEndianBytes.casting())
+    }
+}
diff --git a/Sources/WebAuthn/Helpers/Numbers+Bytes.swift b/Sources/WebAuthn/Helpers/Numbers+Bytes.swift
deleted file mode 100644
index d02ee1f..0000000
--- a/Sources/WebAuthn/Helpers/Numbers+Bytes.swift
+++ /dev/null
@@ -1,34 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-// This source file is part of the WebAuthn Swift open source project
-//
-// Copyright (c) 2022 the WebAuthn Swift project authors
-// Licensed under Apache License v2.0
-//
-// See LICENSE.txt for license information
-// See CONTRIBUTORS.txt for the list of WebAuthn Swift project authors
-//
-// SPDX-License-Identifier: Apache-2.0
-//
-//===----------------------------------------------------------------------===//
-
-import Foundation
-
-public enum Endian {
-    case big, little
-}
-
-protocol IntegerTransform: Sequence where Element: FixedWidthInteger {
-    func toInteger<I: FixedWidthInteger>(endian: Endian) -> I
-}
-
-extension IntegerTransform {
-    func toInteger<I: FixedWidthInteger>(endian: Endian) -> I {
-        // swiftlint:disable:next identifier_name
-        let f = { (accum: I, next: Element) in accum &<< next.bitWidth | I(next) }
-        return endian == .big ? reduce(0, f) : reversed().reduce(0, f)
-    }
-}
-
-extension Data: IntegerTransform {}
-extension Array: IntegerTransform where Element: FixedWidthInteger {}