URGENT: Fix events rejected due to duplicate sent_at header

CHANGELOG.md

@@ -4,9 +4,9 @@
 
 ### Fixes
 
+- URGENT: Fix events rejected due to duplicate `sent_at` header when offline caching is enabled through `CacheDirectoryPath` ([#1818](https://github.com/getsentry/sentry-dotnet/pull/1818))
 - Fix null ref in aspnet TryGetTraceHeader ([#1807](https://github.com/getsentry/sentry-dotnet/pull/1807))
 
-
 ## 3.20.0
 
 ### Features

src/Sentry/Envelopes/Envelope.cs

@@ -56,7 +56,11 @@ private async Task SerializeHeaderAsync(
             ISystemClock clock,
             CancellationToken cancellationToken)
         {
-            var headerItems = Header.Append(SentAtKey, clock.GetUtcNow());
+            // Append the sent_at header, except when writing to disk
+            var headerItems = !stream.IsFileStream()
+                ? Header.Append(SentAtKey, clock.GetUtcNow())
+                : Header;
+
             var writer = new Utf8JsonWriter(stream);
 
 #if NET461 || NETSTANDARD2_0
@@ -72,14 +76,16 @@ private async Task SerializeHeaderAsync(
 
         private void SerializeHeader(Stream stream, IDiagnosticLogger? logger, ISystemClock clock)
         {
-            var headerItems = Header.Append(SentAtKey, clock.GetUtcNow());
+            // Append the sent_at header, except when writing to disk
+            var headerItems = !stream.IsFileStream()
+                ? Header.Append(SentAtKey, clock.GetUtcNow())
+                : Header;
+
             using var writer = new Utf8JsonWriter(stream);
             writer.WriteDictionaryValue(headerItems, logger);
             writer.Flush();
         }
 
-        // Gets the header and adds a sent_at timestamp
-
         /// <inheritdoc />
         public Task SerializeAsync(
             Stream stream,
@@ -270,9 +276,14 @@ internal static Envelope FromClientReport(ClientReport clientReport)
                 prevByte = curByte;
             }
 
-            return
+            var header =
                 Json.Parse(buffer.ToArray(), JsonExtensions.GetDictionaryOrNull)
                 ?? throw new InvalidOperationException("Envelope header is malformed.");
+
+            // The sent_at header should not be included in the result
+            header.Remove(SentAtKey);
+
+            return header;
         }
 
         /// <summary>

src/Sentry/Internal/Extensions/JsonExtensions.cs

@@ -29,7 +29,7 @@ public static void Deconstruct(this JsonProperty jsonProperty, out string name,
             value = jsonProperty.Value;
         }
 
-        public static IReadOnlyDictionary<string, object?>? GetDictionaryOrNull(this JsonElement json)
+        public static Dictionary<string, object?>? GetDictionaryOrNull(this JsonElement json)
         {
             if (json.ValueKind != JsonValueKind.Object)
             {
@@ -46,7 +46,7 @@ public static void Deconstruct(this JsonProperty jsonProperty, out string name,
             return result;
         }
 
-        public static IReadOnlyDictionary<string, string?>? GetStringDictionaryOrNull(this JsonElement json)
+        public static Dictionary<string, string?>? GetStringDictionaryOrNull(this JsonElement json)
         {
             if (json.ValueKind != JsonValueKind.Object)
             {

src/Sentry/Internal/Extensions/StreamExtensions.cs

@@ -60,5 +60,8 @@ public static async Task WriteByteAsync(
                 return null;
             }
         }
+
+        public static bool IsFileStream(this Stream? stream) =>
+            stream is FileStream || stream?.GetType().Name == "MockFileStream";
     }
 }

test/Sentry.Testing/MockClock.cs

@@ -2,7 +2,7 @@
 
 public class MockClock : ISystemClock
 {
-    private readonly DateTimeOffset _value;
+    private DateTimeOffset _value;
 
     public MockClock(DateTimeOffset value) => _value = value;
 
@@ -11,4 +11,6 @@ public MockClock() : this(DateTimeOffset.MaxValue)
     }
 
     public DateTimeOffset GetUtcNow() => _value;
+
+    public void SetUtcNow(DateTimeOffset value) => _value = value;
 }

test/Sentry.Tests/Internals/Http/CachingTransportTests.cs

@@ -1,3 +1,4 @@
+using System.IO.Abstractions.TestingHelpers;
 using System.Net;
 using System.Net.Http;
 using System.Net.Sockets;
@@ -677,4 +678,35 @@ public async Task TransportResumesWhenNetworkComesBackOnline()
         var envelopes = innerTransport.GetSentEnvelopes();
         envelopes.Should().NotBeEmpty();
     }
+
+    [Fact]
+    public async Task DoesntWriteSentAtHeaderToCacheFile()
+    {
+        // Arrange
+        using var cacheDirectory = new TempDirectory(_fileSystem);
+        var options = new SentryOptions
+        {
+            Dsn = ValidDsn,
+            DiagnosticLogger = _logger,
+            Debug = true,
+            CacheDirectoryPath = cacheDirectory.Path,
+            FileSystem = _fileSystem
+        };
+
+        var innerTransport = Substitute.For<ITransport>();
+        await using var transport = CachingTransport.Create(innerTransport, options, startWorker: false);
+
+        using var envelope = Envelope.FromEvent(new SentryEvent());
+
+        // Act
+        await transport.SendEnvelopeAsync(envelope);
+
+        // Assert
+        var filePath = _fileSystem
+            .EnumerateFiles(cacheDirectory.Path, "*", SearchOption.AllDirectories)
+            .Single();
+
+        var contents = _fileSystem.ReadAllTextFromFile(filePath);
+        Assert.DoesNotContain("sent_at", contents);
+    }
 }

test/Sentry.Tests/Protocol/Envelopes/EnvelopeTests.cs

@@ -8,7 +8,7 @@ public class EnvelopeTests
     // https://develop.sentry.dev/sdk/envelopes/#full-examples
 
     private readonly IDiagnosticLogger _testOutputLogger;
-    private readonly ISystemClock _fakeClock;
+    private readonly MockClock _fakeClock;
 
     public EnvelopeTests(ITestOutputHelper output)
     {
@@ -698,4 +698,31 @@ value is IReadOnlyDictionary<string, string> nested &&
                 nested["version"] == SdkVersion.Instance.Version;
         }).Should().BeTrue();
     }
+
+    [Fact]
+    public async Task Serialization_RoundTrip_ReplacesSentAtHeader()
+    {
+        // Arrange
+        using var envelope = new Envelope(
+            new Dictionary<string, object> { ["event_id"] = "12c2d058d58442709aa2eca08bf20986" },
+            Array.Empty<EnvelopeItem>());
+
+        // Act
+        _fakeClock.SetUtcNow(DateTimeOffset.MinValue);
+        var serialized = await envelope.SerializeToStringAsync(_testOutputLogger, _fakeClock);
+
+        using var stream = new MemoryStream();
+        using var writer = new StreamWriter(stream);
+        await writer.WriteAsync(serialized);
+        await writer.FlushAsync();
+        stream.Seek(0, SeekOrigin.Begin);
+        var deserialized = await Envelope.DeserializeAsync(stream);
+
+        _fakeClock.SetUtcNow(DateTimeOffset.MaxValue);
+        var output = await deserialized.SerializeToStringAsync(_testOutputLogger, _fakeClock);
+
+        // Assert
+        output.Should().Be(
+            "{\"event_id\":\"12c2d058d58442709aa2eca08bf20986\",\"sent_at\":\"9999-12-31T23:59:59.9999999+00:00\"}\n");
+    }
 }