fix: RFC3339 date parsing (#2119)

* Add handling for miliseconds in RFC3339 date parsing across identity reoslvers.

* Add swift file extension.

* Remove stale reference

* Add newline at end of file.

* Fix swift 6 compilation errors & add unit tests.

* Add preconcurrency import for ISO8601DateFormatter

---------

Co-authored-by: Sichan Yoo <chanyoo@amazon.com>

Author: sichanyoo

Sources/Core/AWSSDKIdentity/Sources/AWSSDKIdentity/AWSCredentialIdentityResolvers/ECSAWSCredentialIdentityResolver.swift

@@ -218,8 +218,7 @@ private struct JSONCredentialResponse: Codable {
 
         // Handle the Expiration field which is a string in ISO8601 format.
         if let expirationString = try container.decodeIfPresent(String.self, forKey: .expiration) {
-            let formatter = ISO8601DateFormatter()
-            expiration = formatter.date(from: expirationString)
+            expiration = RFC3339DateParser.parse(expirationString)
         } else {
             expiration = nil
         }

Sources/Core/AWSSDKIdentity/Sources/AWSSDKIdentity/AWSCredentialIdentityResolvers/IMDSAWSCredentialIdentityResolver.swift

@@ -156,12 +156,11 @@ private struct JSONCredentialResponse: Codable {
 
     init(from decoder: Decoder) throws {
         let container = try decoder.container(keyedBy: CodingKeys.self)
-        let formatter = ISO8601DateFormatter()
 
         code = try container.decode(String.self, forKey: .code)
 
         let lastUpdatedString = try container.decode(String.self, forKey: .lastUpdated)
-        guard let lastUpdatedDate = formatter.date(from: lastUpdatedString) else {
+        guard let lastUpdatedDate = RFC3339DateParser.parse(lastUpdatedString) else {
             throw DecodingError.dataCorruptedError(forKey: .lastUpdated,
                 in: container,
                 debugDescription: "Invalid ISO8601 date string: \(lastUpdatedString)")
@@ -174,7 +173,7 @@ private struct JSONCredentialResponse: Codable {
         token = try container.decode(String.self, forKey: .token)
 
         let expirationString = try container.decode(String.self, forKey: .expiration)
-        guard let expirationDate = formatter.date(from: expirationString) else {
+        guard let expirationDate = RFC3339DateParser.parse(expirationString) else {
             throw DecodingError.dataCorruptedError(forKey: .expiration,
                 in: container,
                 debugDescription: "Invalid ISO8601 date string: \(expirationString)")

Sources/Core/AWSSDKIdentity/Sources/AWSSDKIdentity/AWSCredentialIdentityResolvers/LoginAWSCredentialIdentityResolver.swift

@@ -143,17 +143,11 @@ public struct LoginAWSCredentialIdentityResolver: AWSCredentialIdentityResolver
             decoder.dateDecodingStrategy = .custom { decoder in
                 let container = try decoder.singleValueContainer()
                 let dateString = try container.decode(String.self)
-                let formatter = ISO8601DateFormatter()
-                // Powershell saves expiration date with milliseconds.
-                formatter.formatOptions = [.withInternetDateTime, .withFractionalSeconds]
-                if let date = formatter.date(from: dateString) {
-                    return date
-                }
-                // AWS CLI saves expiration date without milliseconds.
-                // Because setting .withFractionalSeconds is a strict requirement, must remove it for AWS CLI expiration date.
-                formatter.formatOptions = [.withInternetDateTime]
-                guard let date = formatter.date(from: dateString) else {
-                    throw DecodingError.dataCorruptedError(in: container, debugDescription: "Invalid date format")
+                guard let date = RFC3339DateParser.parse(dateString) else {
+                    throw DecodingError.dataCorruptedError(
+                        in: container,
+                        debugDescription: "Invalid RFC3339 date format"
+                    )
                 }
                 return date
             }

Sources/Core/AWSSDKIdentity/Sources/AWSSDKIdentity/AWSCredentialIdentityResolvers/ProcessAWSCredentialIdentityResolver.swift

@@ -187,8 +187,7 @@ private struct ProcessJSONCredentialResponse: Codable {
 
         // Handle the Expiration field which is a string in ISO8601 format.
         if let expirationString = try container.decodeIfPresent(String.self, forKey: .expiration) {
-            let formatter = ISO8601DateFormatter()
-            expiration = formatter.date(from: expirationString)
+            expiration = RFC3339DateParser.parse(expirationString)
         } else {
             expiration = nil
         }

Sources/Core/AWSSDKIdentity/Sources/AWSSDKIdentity/BearerTokenIdentityResolvers/SSOBearerTokenIdentityResolver.swift

@@ -236,10 +236,8 @@ struct SSOToken: Codable {
         // Required fields.
 
         accessToken = try container.decode(String.self, forKey: .accessToken)
-        let dateFormatter = ISO8601DateFormatter()
-        dateFormatter.formatOptions = [.withInternetDateTime]
         let expiresAtString = try container.decode(String.self, forKey: .expiresAt)
-        guard let expiresAtDate = dateFormatter.date(from: expiresAtString) else {
+        guard let expiresAtDate = RFC3339DateParser.parse(expiresAtString) else {
             throw DecodingError.dataCorruptedError(
                 forKey: .expiresAt,
                 in: container,
@@ -259,7 +257,7 @@ struct SSOToken: Codable {
             String.self,
             forKey: .registrationExpiresAt
         ) {
-            registrationExpiresAt = dateFormatter.date(from: registrationExpiresAtString)
+            registrationExpiresAt = RFC3339DateParser.parse(registrationExpiresAtString)
         } else {
             registrationExpiresAt = nil
         }

Sources/Core/AWSSDKIdentity/Sources/AWSSDKIdentity/RFC3339DateParser.swift

@@ -0,0 +1,21 @@
+// ISO8601DateFormatter isn't Sendable yet.
+@preconcurrency import Foundation
+
+public enum RFC3339DateParser {
+    private static let withFractional: ISO8601DateFormatter = {
+        let f = ISO8601DateFormatter()
+        f.formatOptions = [.withInternetDateTime, .withFractionalSeconds]
+        return f
+    }()
+
+    private static let withoutFractional: ISO8601DateFormatter = {
+        let f = ISO8601DateFormatter()
+        f.formatOptions = [.withInternetDateTime]
+        return f
+    }()
+
+    public static func parse(_ string: String) -> Date? {
+        withoutFractional.date(from: string)
+        ?? withFractional.date(from: string)
+    }
+}

Sources/Core/AWSSDKIdentity/Tests/AWSSDKIdentityTests/RFC3339DateParserTests.swift

@@ -0,0 +1,33 @@
+//
+// Copyright Amazon.com Inc. or its affiliates.
+// All Rights Reserved.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+
+import XCTest
+import enum AWSSDKIdentity.RFC3339DateParser
+
+class RFC3339DateParserTests: XCTestCase {
+    func testWithFractionalSecond() {
+        let dateString = "2024-07-15T12:30:45.123Z"
+        let parsedDate = RFC3339DateParser.parse(dateString)
+        // 2024-07-15T12:30:45.123Z = 1721046645.123 seconds since Unix epoch
+        let expectedDate = Date(timeIntervalSince1970: 1_721_046_645.123)
+        XCTAssertEqual(expectedDate, parsedDate)
+    }
+
+    func testWithoutFractionalSecond() {
+        let dateString = "2024-07-15T12:30:45Z"
+        let parsedDate = RFC3339DateParser.parse(dateString)
+        // 2024-07-15T12:30:45Z = 1721046645 seconds since Unix epoch
+        let expectedDate = Date(timeIntervalSince1970: 1_721_046_645)
+        XCTAssertEqual(expectedDate, parsedDate)
+    }
+
+    func testInvalidDateReturnsNil() {
+        let dateString = "not-a-date"
+        let parsedDate = RFC3339DateParser.parse(dateString)
+        XCTAssertNil(parsedDate)
+    }
+}