Merge pull request #51 from outfoxx/fix/base64

Allow unpadded base64 when decoding
outfoxx · Feb 20, 2023 · 87b95c9 · 87b95c9
2 parents e724100 + b690408
commit 87b95c9
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Showing 6 changed files with 95 additions and 4 deletions.
diff --git a/Sources/PotentCBOR/CBORDecoder.swift b/Sources/PotentCBOR/CBORDecoder.swift
@@ -425,7 +425,7 @@ public struct CBORDecoderTransform: InternalDecoderTransform, InternalValueDeser
     switch value {
     case .byteString(let data), .tagged(_, .byteString(let data)): return data
     case .tagged(.base64, .utf8String(let string)):
-      guard let data = Data(base64Encoded: string) else {
+      guard let data = Data(base64EncodedUnpadded: string) else {
         throw DecodingError.dataCorruptedError(in: decoder, debugDescription: "Expected Base64 encoded string")
       }
       return data
@@ -575,8 +575,19 @@ public struct CBORDecoderTransform: InternalDecoderTransform, InternalValueDeser
 
 extension Data {
 
+  init?(base64EncodedUnpadded string: String) {
+    self.init(base64Encoded: Data.padBase64(string))
+  }
+
   init?(base64UrlEncoded string: String) {
-    self.init(base64Encoded: string.replacingOccurrences(of: "-", with: "+").replacingOccurrences(of: "_", with: "/"))
+    let base64String = string.replacingOccurrences(of: "-", with: "+").replacingOccurrences(of: "_", with: "/")
+    self.init(base64EncodedUnpadded: base64String)
+  }
+
+  private static func padBase64(_ string: String) -> String {
+    let offset = string.count % 4
+    guard offset != 0 else { return string }
+    return string.padding(toLength: string.count + 4 - offset, withPad: "=", startingAt: 0)
   }
 
 }

diff --git a/Sources/PotentJSON/JSONDecoder.swift b/Sources/PotentJSON/JSONDecoder.swift
@@ -451,7 +451,7 @@ public struct JSONDecoderTransform: InternalDecoderTransform, InternalValueDeser
         throw DecodingError.typeMismatch(at: decoder.codingPath, expectation: type, reality: value)
       }
 
-      guard let data = Data(base64Encoded: string) else {
+      guard let data = Data(base64EncodedUnpadded: string) else {
         throw DecodingError.dataCorrupted(.init(
           codingPath: decoder.codingPath,
           debugDescription: "Encountered Data is not valid Base64."
@@ -535,6 +535,20 @@ public struct JSONDecoderTransform: InternalDecoderTransform, InternalValueDeser
 
 }
 
+extension Data {
+
+  init?(base64EncodedUnpadded string: String) {
+    self.init(base64Encoded: Data.padBase64(string))
+  }
+
+  private static func padBase64(_ string: String) -> String {
+    let offset = string.count % 4
+    guard offset != 0 else { return string }
+    return string.padding(toLength: string.count + 4 - offset, withPad: "=", startingAt: 0)
+  }
+
+}
+
 
 #if canImport(Combine)
 

diff --git a/Sources/PotentYAML/YAMLDecoder.swift b/Sources/PotentYAML/YAMLDecoder.swift
@@ -470,7 +470,7 @@ public struct YAMLDecoderTransform: InternalDecoderTransform, InternalValueDeser
         throw DecodingError.typeMismatch(at: decoder.codingPath, expectation: type, reality: value)
       }
 
-      guard let data = Data(base64Encoded: string) else {
+      guard let data = Data(base64EncodedUnpadded: string) else {
         throw DecodingError.dataCorrupted(.init(
           codingPath: decoder.codingPath,
           debugDescription: "Encountered Data is not valid Base64."
@@ -578,6 +578,20 @@ public struct YAMLDecoderTransform: InternalDecoderTransform, InternalValueDeser
 
 }
 
+extension Data {
+
+  init?(base64EncodedUnpadded string: String) {
+    self.init(base64Encoded: Data.padBase64(string))
+  }
+
+  private static func padBase64(_ string: String) -> String {
+    let offset = string.count % 4
+    guard offset != 0 else { return string }
+    return string.padding(toLength: string.count + 4 - offset, withPad: "=", startingAt: 0)
+  }
+
+}
+
 
 
 #if canImport(Combine)

diff --git a/Tests/CBORDecoderTests.swift b/Tests/CBORDecoderTests.swift
@@ -927,6 +927,12 @@ class CBORDecoderTests: XCTestCase {
                                                             0x44, 0x42, 0x41, 0x55, 0x2B])),
       Data([1, 2, 3, 4, 5, 62])
     )
+    // Unpadded
+    XCTAssertEqual(
+      try CBORDecoder.default.decode(Data.self, from: Data([0xD8, 0x22, 0x66, 0x41, 0x51, 0x49,
+                                                            0x44, 0x42, 0x41])),
+      Data([1, 2, 3, 4])
+    )
     XCTAssertThrowsError(
       try CBORDecoder.default.decode(Data.self, from: Data([0xD8, 0x22, 0x68, 0x41, 0x51, 0x49,
                                                             0x44, 0x42, 0x41, 0x55, 0x60]))
@@ -941,6 +947,12 @@ class CBORDecoderTests: XCTestCase {
                                                             0x44, 0x42, 0x41, 0x55, 0x2D])),
       Data([1, 2, 3, 4, 5, 62])
     )
+    // Unpadded
+    XCTAssertEqual(
+      try CBORDecoder.default.decode(Data.self, from: Data([0xD8, 0x21, 0x66, 0x41, 0x51, 0x49,
+                                                            0x44, 0x42, 0x41])),
+      Data([1, 2, 3, 4])
+    )
     XCTAssertThrowsError(
       try CBORDecoder.default.decode(Data.self, from: Data([0xD8, 0x21, 0x68, 0x41, 0x51, 0x49,
                                                             0x44, 0x42, 0x41, 0x55, 0x60]))

diff --git a/Tests/JSONDecoderTests.swift b/Tests/JSONDecoderTests.swift
@@ -268,6 +268,23 @@ class JSONDecoderTests: XCTestCase {
     XCTAssertEqual(testValue.data, data)
   }
 
+  func testDecodeBase64DataUnpadded() throws {
+
+    let data = "1234".data(using: .utf8)!
+
+    struct TestValue: Codable {
+      var data: Data
+    }
+
+    let json = #"{"data":"\#(data.base64EncodedString().replacingOccurrences(of: "=", with: ""))"}"#
+
+    let decoder = JSON.Decoder()
+    decoder.dataDecodingStrategy = .base64
+
+    let testValue = try decoder.decode(TestValue.self, from: json)
+    XCTAssertEqual(testValue.data, data)
+  }
+
   func testDecodeDeferredToData() throws {
 
     let data = "Hello World!".data(using: .utf8)!

diff --git a/Tests/YAMLDecoderTests.swift b/Tests/YAMLDecoderTests.swift
@@ -340,6 +340,29 @@ class YAMLDecoderTests: XCTestCase {
     XCTAssertEqual(testValue.data, data)
   }
 
+  func testDecodeBase64DataUnpadded() throws {
+
+    let data = "1234".data(using: .utf8)!
+
+    struct TestValue: Codable {
+      var data: Data
+    }
+
+    let yaml =
+    """
+    ---
+    data: \(data.base64EncodedString().replacingOccurrences(of: "=", with: ""))
+    ...
+
+    """
+
+    let decoder = YAML.Decoder()
+    decoder.dataDecodingStrategy = .base64
+
+    let testValue = try decoder.decode(TestValue.self, from: yaml)
+    XCTAssertEqual(testValue.data, data)
+  }
+
   func testDecodeDeferredToData() throws {
 
     let data = "Hello World!".data(using: .utf8)!