Merge pull request #454 from nblumhardt/detect-zero-traceids

Detect and drop all-zero trace/span/parent ids

Author: nblumhardt

src/SeqCli/Apps/Hosting/AppContainer.cs

@@ -15,6 +15,7 @@
 using System;
 using System.Globalization;
 using System.IO;
+using System.Linq;
 using System.Text.RegularExpressions;
 using System.Threading.Tasks;
 using Newtonsoft.Json;
@@ -35,7 +36,7 @@ partial class AppContainer : IAppHost, IDisposable
     readonly SeqApp _seqApp;
     readonly AppLoader _loader;
 
-    static readonly Regex HexDigits = HexDigitsRegex();
+    static readonly Regex NonZeroHex = NonZeroHexRegex();
 
     readonly JsonSerializer _serializer = JsonSerializer.Create(new JsonSerializerSettings
     {
@@ -183,7 +184,7 @@ static bool IsValidHexIdentifier(JToken? value, int requiredChars)
         if (value?.Value<string>() is not { } id)
             return false;
 
-        return id.Length == requiredChars && HexDigits.IsMatch(id);
+        return id.Length == requiredChars && NonZeroHex.IsMatch(id);
     }
 
     public void StartPublishing(TextWriter inputWriter)
@@ -198,7 +199,6 @@ public void StopPublishing()
             pjson.Stop();
     }
 
-    // Technically, 
-    [GeneratedRegex("^[0-9a-f]*$")]
-    private static partial Regex HexDigitsRegex();
-}
+    [GeneratedRegex("^0*[1-9a-f][0-9a-f]*$")]
+    private static partial Regex NonZeroHexRegex();
+}

test/SeqCli.Tests/Apps/AppContainerTests.cs

@@ -67,6 +67,20 @@ public void RemovesShortTraceAndSpanIds()
         Assert.Empty(jo);
     }
 
+    [Fact]
+    public void RemovesZeroTraceAndSpanIds()
+    {
+        var jo = new JObject
+        {
+            ["@tr"] = "00000000000000000000000000000000",
+            ["@sp"] = "0000000000000000",
+            ["@ps"] = "0000000000000000"
+        };
+        Assert.NotEmpty(jo);
+        AppContainer.SanitizeTraceIdentifiers(jo);
+        Assert.Empty(jo);
+    }
+
     [Fact]
     public void PreservesValidTraceAndSpanIds()
     {