Parse ASN.1 UTCTime according to spec

Supports optional seconds and compact formatted time zone offets.

Also removes force unwrap in decoding, superceding and closing #19

Sources/PotentASN1/ASN1.swift

@@ -95,7 +95,7 @@ public indirect enum ASN1: Value {
   case teletexString(String)
   case videotexString(String)
   case ia5String(String)
-  case utcTime(Date)
+  case utcTime(ZonedDate)
   case generalizedTime(ZonedDate)
   case graphicString(String)
   case visibleString(String)
@@ -170,7 +170,7 @@ public indirect enum ASN1: Value {
     case .teletexString(let value): return AnyString(value, kind: .teletex)
     case .videotexString(let value): return AnyString(value, kind: .videotex)
     case .ia5String(let value): return AnyString(value, kind: .ia5)
-    case .utcTime(let value): return AnyTime(date: value, timeZone: .utc, kind: .utc)
+    case .utcTime(let value): return AnyTime(value, kind: .utc)
     case .generalizedTime(let value): return AnyTime(value, kind: .generalized)
     case .graphicString(let value): return AnyString(value, kind: .graphic)
     case .visibleString(let value): return AnyString(value, kind: .visible)
@@ -312,7 +312,7 @@ public extension ASN1 {
     return value
   }
 
-  var utcTimeValue: Date? {
+  var utcTimeValue: ZonedDate? {
     guard case .utcTime(let value) = absolute else { return nil }
     return value
   }
@@ -372,7 +372,7 @@ public extension ASN1 {
 
   var timeValue: (ZonedDate, AnyTime.Kind)? {
     switch absolute {
-    case .utcTime(let date): return (ZonedDate(date: date, timeZone: .utc), .utc)
+    case .utcTime(let date): return (date, .utc)
     case .generalizedTime(let date): return (date, .generalized)
     default: return nil
     }
@@ -447,7 +447,7 @@ extension ASN1: Codable {
     case .ia5String:
       self = .ia5String(try container.decode(String.self))
     case .utcTime:
-      self = .utcTime(try container.decode(Date.self))
+      self = .utcTime(try container.decode(ZonedDate.self))
     case .generalizedTime:
       self = .generalizedTime(try container.decode(ZonedDate.self))
     case .graphicString:

Sources/PotentASN1/ASN1Encoder.swift

@@ -426,7 +426,7 @@ extension SchemaState {
         func asn1Time(_ zonedDate: ZonedDate) -> ASN1 {
           switch requiredKind {
           case .generalized: return .generalizedTime(zonedDate)
-          case .utc: return .utcTime(zonedDate.utcDate)
+          case .utc: return .utcTime(zonedDate)
           }
         }
 

Sources/PotentASN1/ASN1Reader.swift

@@ -20,6 +20,7 @@ public enum DERReader {
     case invalidStringEncoding
     case invalidStringCharacters
     case nonConstructedCollection
+    case invalidUTCTime
     case invalidGeneralizedTime
   }
 
@@ -143,7 +144,10 @@ public enum DERReader {
 
     case .utcTime:
       let string = try parseString(&itemBuffer, tag: tag, encoding: .ascii)
-      return .utcTime(utcDateFormatter.date(from: string)!)
+      guard let zonedDate = utcFormatter.date(from: string) else {
+        throw Error.invalidUTCTime
+      }
+      return .utcTime(zonedDate)
 
     case .generalizedTime:
       let string = try parseString(&itemBuffer, tag: tag, encoding: .ascii)
@@ -320,17 +324,10 @@ private extension UnsafeBufferPointer {
 }
 
 
-private let utcDateFormatter: DateFormatter = {
-  let fmt = DateFormatter()
-  fmt.timeZone = TimeZone(abbreviation: "UTC")
-  fmt.dateFormat = "yyMMddHHmmss'Z'"
-  return fmt
-}()
-
-
 private extension String {
   var hasFractionalSeconds: Bool { contains(".") }
   var hasZone: Bool { contains("+") || contains("-") || contains("Z") }
 }
 
-private let generalizedFormatter = ISO8601SuffixedDateFormatter(basePattern: "yyyyMMddHHmmss")
+private let utcFormatter = SuffixedDateFormatter(basePattern: "yyMMddHHmm", secondsPattern: "ss") { $0.count > 10 }
+private let generalizedFormatter = SuffixedDateFormatter.optionalFractionalSeconds(basePattern: "yyyyMMddHHmmss")

Sources/PotentASN1/ASN1Writer.swift

@@ -195,13 +195,14 @@ public class DERWriter {
       append(data: ascii)
 
     case .utcTime(let value):
-      let ascii = utcDateFormatter.string(from: value).data(using: String.Encoding.ascii)!
+      let formatter = UTCFormatters.for(timeZone: value.timeZone)
+      let ascii = formatter.string(from: value.date).data(using: .ascii)!
       append(tag: .utcTime, length: ascii.count)
       append(data: ascii)
 
     case .generalizedTime(let value):
       let formatter = GeneralizedFormatters.for(timeZone: value.timeZone)
-      let ascii = formatter.string(from: value.date).data(using: String.Encoding.ascii)!
+      let ascii = formatter.string(from: value.date).data(using: .ascii)!
       append(tag: .generalizedTime, length: ascii.count)
       append(data: ascii)
 
@@ -247,14 +248,31 @@ public class DERWriter {
 
 }
 
+private enum UTCFormatters {
 
-private let utcDateFormatter: DateFormatter = {
-  let fmt = DateFormatter()
-  fmt.locale = Locale(identifier: "en_US_POSIX")
-  fmt.timeZone = .utc
-  fmt.dateFormat = "yyMMddHHmmss'Z'"
-  return fmt
-}()
+  private static var utcFormatters: [TimeZone: DateFormatter] = [:]
+  private static let utcFormattersLock = NSLock()
+
+  static func `for`(timeZone: TimeZone) -> DateFormatter {
+    utcFormattersLock.lock()
+    defer { utcFormattersLock.unlock() }
+
+    if let found = utcFormatters[timeZone] {
+      return found
+    }
+
+    let formatter = DateFormatter()
+    formatter.calendar = Calendar(identifier: .iso8601)
+    formatter.locale = Locale(identifier: "en_US_POSIX")
+    formatter.timeZone = timeZone
+    formatter.dateFormat = timeZone == .utc ? "yyMMddHHmmss'Z'" : "yyMMddHHmmssZ"
+
+    utcFormatters[timeZone] = formatter
+
+    return formatter
+  }
+
+}
 
 private enum GeneralizedFormatters {
 

Sources/PotentCBOR/CBORDecoder.swift

@@ -384,7 +384,7 @@ public struct CBORDecoderTransform: InternalDecoderTransform, InternalValueDeser
 }
 
 
-private let _iso8601Formatter = ISO8601SuffixedDateFormatter(basePattern: "yyyy-MM-dd'T'HH:mm:ss")
+private let _iso8601Formatter = SuffixedDateFormatter.optionalFractionalSeconds(basePattern: "yyyy-MM-dd'T'HH:mm:ss")
 
 
 #if canImport(Combine)

Sources/PotentCodables/Dates.swift

@@ -10,14 +10,21 @@
 
 import Foundation
 
-public struct ISO8601SuffixedDateFormatter {
+public struct SuffixedDateFormatter {
+
+  public static func optionalFractionalSeconds(basePattern: String) -> SuffixedDateFormatter {
+    SuffixedDateFormatter(basePattern: basePattern, secondsPattern: ".S") { $0.contains(".") }
+  }
 
   private let noSuffixes: DateFormatter
   private let zoneSuffix: DateFormatter
-  private let fractionalSecondsSuffix: DateFormatter
-  private let zoneAndFractionalSecondsSuffixes: DateFormatter
+  private let secondsSuffix: DateFormatter
+  private let zoneAndSecondsSuffixes: DateFormatter
+  private let checkHasSeconds: (String) -> Bool
+
+  public init(basePattern: String, secondsPattern: String, checkHasSeconds: @escaping (String) -> Bool) {
+    self.checkHasSeconds = checkHasSeconds
 
-  public init(basePattern: String) {
     noSuffixes = {
       let formatter = DateFormatter()
       formatter.calendar = Calendar(identifier: .iso8601)
@@ -36,34 +43,37 @@ public struct ISO8601SuffixedDateFormatter {
       return formatter
     }()
 
-    fractionalSecondsSuffix = {
+    secondsSuffix = {
       let formatter = DateFormatter()
       formatter.calendar = Calendar(identifier: .iso8601)
       formatter.locale = Locale(identifier: "en_US_POSIX")
       formatter.timeZone = TimeZone(secondsFromGMT: 0)
-      formatter.dateFormat = "\(basePattern).S"
+      formatter.dateFormat = "\(basePattern)\(secondsPattern)"
       return formatter
     }()
 
-    zoneAndFractionalSecondsSuffixes = {
+    zoneAndSecondsSuffixes = {
       let formatter = DateFormatter()
       formatter.calendar = Calendar(identifier: .iso8601)
       formatter.locale = Locale(identifier: "en_US_POSIX")
       formatter.timeZone = TimeZone(secondsFromGMT: 0)
-      formatter.dateFormat = "\(basePattern).SXXXX"
+      formatter.dateFormat = "\(basePattern)\(secondsPattern)XXXX"
       return formatter
     }()
   }
 
   public func date(from string: String) -> ZonedDate? {
     let parsedDate: Date?
-    if string.hasFractionalSeconds, string.hasZone {
-      parsedDate = zoneAndFractionalSecondsSuffixes.date(from: string)
+    let zoneStartIndex = string.firstIndex { $0 == "-" || $0 == "+" || $0 == "Z" } ?? string.endIndex
+    let stringWithoutZone = String(string[string.startIndex ..< zoneStartIndex])
+    let hasZone = string != stringWithoutZone
+    if checkHasSeconds(stringWithoutZone) && hasZone {
+      parsedDate = zoneAndSecondsSuffixes.date(from: string)
     }
-    else if string.hasFractionalSeconds {
-      parsedDate = fractionalSecondsSuffix.date(from: string)
+    else if checkHasSeconds(stringWithoutZone) {
+      parsedDate = secondsSuffix.date(from: string)
     }
-    else if string.hasZone {
+    else if hasZone {
       parsedDate = zoneSuffix.date(from: string)
     }
     else {
@@ -77,8 +87,3 @@ public struct ISO8601SuffixedDateFormatter {
   }
 
 }
-
-private extension String {
-  var hasFractionalSeconds: Bool { contains(".") }
-  var hasZone: Bool { contains("+") || contains("-") || contains("Z") }
-}

Sources/PotentJSON/JSONDecoder.swift

@@ -361,7 +361,7 @@ public struct JSONDecoderTransform: InternalDecoderTransform, InternalValueDeser
 }
 
 
-private let _iso8601Formatter = ISO8601SuffixedDateFormatter(basePattern: "yyyy-MM-dd'T'HH:mm:ss")
+private let _iso8601Formatter = SuffixedDateFormatter.optionalFractionalSeconds(basePattern: "yyyy-MM-dd'T'HH:mm:ss")
 
 
 #if canImport(Combine)

Sources/PotentYAML/YAMLDecoder.swift

@@ -393,7 +393,7 @@ public struct YAMLDecoderTransform: InternalDecoderTransform, InternalValueDeser
 }
 
 
-private let _iso8601Formatter = ISO8601SuffixedDateFormatter(basePattern: "yyyy-MM-dd'T'HH:mm:ss")
+private let _iso8601Formatter = SuffixedDateFormatter.optionalFractionalSeconds(basePattern: "yyyy-MM-dd'T'HH:mm:ss")
 
 
 #if canImport(Combine)

Tests/ASN1Tests.swift

@@ -172,6 +172,64 @@ class ASN1Tests: XCTestCase {
     XCTAssertEqual(offset(23), -39600)
   }
 
+  func testUTCTimeEncodingDecoding() throws {
+
+    struct TestStruct: Codable, Equatable {
+      let a: AnyTime
+      let b: AnyTime
+    }
+
+    let TestStructSchema: Schema =
+      .sequence([
+        "a": .time(kind: .utc),
+        "b": .time(kind: .utc),
+      ])
+
+    let src = TestStruct(
+      a: AnyTime(date: Date().truncatedToSecs, timeZone: .utc, kind: .utc),
+      b: AnyTime(date: Date().truncatedToSecs, timeZone: .timeZone(from: "+1122")!, kind: .utc)
+    )
+    let srcData = try ASN1Encoder(schema: TestStructSchema).encode(src)
+    let dst = try ASN1Decoder(schema: TestStructSchema).decode(TestStruct.self, from: srcData)
+
+    XCTAssertEqual(src, dst)
+  }
+
+  func testUTCTimeReadingWriting() throws {
+
+    let writer = DERWriter()
+
+    try writer.write(ASN1.tagged(23, "2211112233Z".data(using: .ascii)!))
+    try writer.write(ASN1.tagged(23, "221111223344Z".data(using: .ascii)!))
+
+    try writer.write(ASN1.tagged(23, "2211112233+1122".data(using: .ascii)!))
+    try writer.write(ASN1.tagged(23, "221111223344+1122".data(using: .ascii)!))
+
+    try writer.write(ASN1.tagged(23, "2211112233-1122".data(using: .ascii)!))
+    try writer.write(ASN1.tagged(23, "221111223344-1122".data(using: .ascii)!))
+
+    let values = try DERReader.parse(data: writer.data)
+
+    func date(_ index: Int) -> TimeInterval { values[index].utcTimeValue!.date.timeIntervalSince1970 }
+    func tz(_ index: Int) -> TimeZone { values[index].utcTimeValue!.timeZone }
+    func offset(_ index: Int) -> Int { values[index].utcTimeValue!.timeZone.secondsFromGMT() }
+
+    XCTAssertEqual(date(0), 1_668_205_980.0)
+    XCTAssertEqual(tz(0), .utc)
+    XCTAssertEqual(date(1), 1_668_206_024.0)
+    XCTAssertEqual(tz(1), .utc)
+
+    XCTAssertEqual(date(2), 1_668_165_060.0)
+    XCTAssertEqual(offset(2), 40920)
+    XCTAssertEqual(date(3), 1_668_165_104.0)
+    XCTAssertEqual(offset(3), 40920)
+
+    XCTAssertEqual(date(4), 1_668_246_900.0)
+    XCTAssertEqual(offset(4), -40920)
+    XCTAssertEqual(date(5), 1_668_246_944.0)
+    XCTAssertEqual(offset(5), -40920)
+  }
+
 }