Backport DateTimeOffset.ToUnixTimeSeconds

Author: Matthias Gessinger

src/AspNet/WebApi/src/Asp.Versioning.WebApi/Asp.Versioning.WebApi.csproj

@@ -21,6 +21,7 @@
   <Compile Include="$(BackportDir)BitOperations.cs" Visible="false" />
   <Compile Include="$(BackportDir)HashCode.cs" Visible="false" />
   <Compile Include="$(BackportDir)NullableAttributes.cs" Visible="false" />
+  <Compile Include="$(BackportDir)DateTimeOffsetExtensions.cs" Visible="false" />
  </ItemGroup>
 
  <ItemGroup>

src/AspNet/WebApi/src/Asp.Versioning.WebApi/System.Net.Http/HttpResponseMessageExtensions.cs

@@ -16,8 +16,6 @@ public static class HttpResponseMessageExtensions
     private const string Deprecation = nameof( Deprecation );
     private const string Link = nameof( Link );
 
-    private static readonly DateTime unixEpoch = new DateTime( 1970, 1, 1 );
-
     /// <summary>
     /// Writes the sunset policy to the specified HTTP response.
     /// </summary>
@@ -50,14 +48,11 @@ public static void WriteDeprecationPolicy( this HttpResponseMessage response, De
 
         var headers = response.Headers;
 
-        if ( deprecationPolicy.Date.HasValue )
+        if ( deprecationPolicy.Date is { } when )
         {
-            long unixTimestamp;
-            DateTimeOffset deprecationDate = deprecationPolicy.Date.Value;
-
-            unixTimestamp = (int) deprecationDate.Subtract( unixEpoch ).TotalSeconds;
+            var unixTimestamp = when.ToUnixTimeSeconds();
 
-            headers.Add( Deprecation, $"@{unixTimestamp}" );
+            headers.Add( Deprecation, unixTimestamp.ToString( "'@'0" ) );
         }
 
         AddLinkHeaders( headers, deprecationPolicy.Links );

src/AspNet/WebApi/test/Asp.Versioning.WebApi.Tests/DefaultApiVersionReporterTest.cs

@@ -51,7 +51,8 @@ public void report_should_add_expected_headers()
         // assert
         var headers = response.Headers;
 
-        long unixTimestamp = (int) deprecationDate.Subtract( new DateTime( 1970, 1, 1 ) ).TotalSeconds;
+        // This line uses an explicit calculation of the unix timestamp to surface any bugs in the backport of ToUnixTimeSeconds.
+        var unixTimestamp = (long) deprecationDate.Subtract( new DateTime( 1970, 1, 1 ) ).TotalSeconds;
 
         headers.GetValues( "api-supported-versions" ).Should().Equal( "1.0, 2.0" );
         headers.GetValues( "api-deprecated-versions" ).Should().Equal( "0.9" );

src/AspNetCore/WebApi/src/Asp.Versioning.Http/Http/HttpResponseExtensions.cs

@@ -5,6 +5,7 @@ namespace Microsoft.AspNetCore.Http;
 using Asp.Versioning;
 using Microsoft.Extensions.Primitives;
 using Microsoft.Net.Http.Headers;
+using System.Globalization;
 
 /// <summary>
 /// Provides extension methods for <see cref="HttpResponse"/>.
@@ -66,14 +67,9 @@ public static void WriteDeprecationPolicy( this HttpResponse response, Deprecati
             return;
         }
 
-        if ( deprecationPolicy.Date.HasValue )
+        if ( deprecationPolicy.Date is { } when )
         {
-            long unixTimestamp;
-            DateTimeOffset deprecationDate = deprecationPolicy.Date.Value;
-
-            unixTimestamp = deprecationDate.ToUnixTimeSeconds();
-
-            headers[Deprecation] = $"@{unixTimestamp}";
+            headers[Deprecation] = when.ToUnixTimeSeconds().ToString( "'@'0", CultureInfo.InvariantCulture );
         }
 
         AddLinkHeaders( headers, deprecationPolicy.Links );

src/AspNetCore/WebApi/test/Asp.Versioning.Http.Tests/DefaultApiVersionReporterTest.cs

@@ -61,7 +61,7 @@ public void report_should_add_expected_headers()
         reporter.Report( response.Object, model );
 
         // assert
-        long unixTimestamp = (int) deprecationDate.Subtract( new DateTime( 1970, 1, 1 ) ).TotalSeconds;
+        var unixTimestamp = deprecationDate.ToUnixTimeSeconds();
 
         headers["api-supported-versions"].Should().Equal( "1.0, 2.0" );
         headers["api-deprecated-versions"].Should().Equal( "0.9" );

src/Client/src/Asp.Versioning.Http.Client/System.Net.Http/HttpResponseMessageExtensions.cs

@@ -18,6 +18,10 @@ public static class HttpResponseMessageExtensions
     private const string Deprecation = nameof( Deprecation );
     private const string Link = nameof( Link );
 
+#if NETSTANDARD1_1
+    private static readonly DateTime UnixEpoch = new DateTime( 1970, 1, 1 );
+#endif
+
     /// <summary>
     /// Gets an API sunset policy from the HTTP response.
     /// </summary>
@@ -89,12 +93,20 @@ public static DeprecationPolicy ReadDeprecationPolicy( this HttpResponseMessage
 
             foreach ( var value in values )
             {
-                var split = value.Trim( '@' );
-                if ( long.TryParse( split, out var unixTimestamp ) )
+                if ( value.Length < 2 || value[0] != '@' )
                 {
-                    DateTimeOffset parsed;
+                    continue;
+                }
+
 #if NETSTANDARD
-                    parsed = new DateTime(1970, 1, 1) + TimeSpan.FromSeconds(unixTimestamp);
+                if ( long.TryParse( value.Substring( 1 ), out var unixTimestamp ) )
+#else
+                if ( long.TryParse( value.AsSpan()[1..], out var unixTimestamp ) )
+#endif
+                {
+                    DateTimeOffset parsed;
+#if NETSTANDARD1_1
+                    parsed = UnixEpoch + TimeSpan.FromSeconds( unixTimestamp );
 #else
                     parsed = DateTimeOffset.FromUnixTimeSeconds( unixTimestamp );
 #endif

src/Common/src/Common.Backport/DateTimeOffsetExtensions.cs

@@ -0,0 +1,15 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved.
+
+namespace System;
+
+internal static class DateTimeOffsetExtensions
+{
+    private const long UnixEpochSeconds = 62_135_596_800L;
+
+    // REF: https://github.com/dotnet/dotnet/blob/main/src/runtime/src/libraries/System.Private.CoreLib/src/System/DateTimeOffset.cs#L745
+    public static long ToUnixTimeSeconds( this DateTimeOffset dateTimeOffset )
+    {
+        var seconds = (long) ( (ulong) dateTimeOffset.UtcTicks / TimeSpan.TicksPerSecond );
+        return seconds - UnixEpochSeconds;
+    }
+}