Add DiagnosticSource version check rule

src/OpenTelemetry.AutoInstrumentation.StartupHook/RulesEngine/DiagnosticSourceRule.cs

@@ -14,13 +14,88 @@
 // limitations under the License.
 // </copyright>
 
+using System.Diagnostics;
+using System.Reflection;
+using OpenTelemetry.AutoInstrumentation.Logging;
+
 namespace OpenTelemetry.AutoInstrumentation.RulesEngine;
 
 internal class DiagnosticSourceRule : Rule
 {
+    private static IOtelLogger logger = OtelLogging.GetLogger("StartupHook");
+
+    public DiagnosticSourceRule()
+    {
+        Name = "System.Diagnostics.DiagnosticSource Validator";
+        Description = "Ensure that the System.Diagnostics.DiagnosticSource version is not older than the version used by the Auto-Instrumentation";
+    }
+
+    // This constructor is used for test purpose.
+    protected DiagnosticSourceRule(IOtelLogger otelLogger)
+        : this()
+    {
+        logger = otelLogger;
+    }
+
     internal override bool Evaluate()
     {
-        // TODO: implement checking logic
+        string? olderDiagnosticSourcePackageVersion = null;
+
+        try
+        {
+            // NuGet package version is not available at runtime. AssemblyVersion is available but it only changes in major version updates.
+            // Thus using AssemblyFileVersion to compare whether the loaded version is older than that of auto instrumentation.
+            var loadedDiagnosticSourceFileVersion = GetVersionFromApp();
+            if (loadedDiagnosticSourceFileVersion != null)
+            {
+                var autoInstrumentationDiagnosticSourceFileVersion = GetVersionFromAutoInstrumentation();
+                if (loadedDiagnosticSourceFileVersion < autoInstrumentationDiagnosticSourceFileVersion)
+                {
+                    olderDiagnosticSourcePackageVersion = loadedDiagnosticSourceFileVersion.ToString();
+                }
+            }
+        }
+        catch (Exception ex)
+        {
+            // Exception in evaluation should not throw or crash the process.
+            logger.Warning($"Rule Engine: Couldn't evaluate reference to System.Diagnostics.DiagnosticSource in an app. Exception: {ex}");
+            return false;
+        }
+
+        if (olderDiagnosticSourcePackageVersion != null)
+        {
+            logger.Error($"Rule Engine: Application has direct or indirect reference to older version of System.Diagnostics.DiagnosticSource.dll {olderDiagnosticSourcePackageVersion}.");
+            return false;
+        }
+
+        logger.Information("Rule Engine: DiagnosticSourceRule evaluation success.");
         return true;
     }
+
+    protected virtual Version? GetVersionFromApp()
+    {
+        // Look up for type with an assembly name, will load the library.
+        // The loaded version depends on the app's reference to the package.
+        var diagnosticSourceType = Type.GetType("System.Diagnostics.DiagnosticSource, System.Diagnostics.DiagnosticSource");
+        if (diagnosticSourceType != null)
+        {
+            var loadedDiagnosticSourceAssembly = Assembly.GetAssembly(diagnosticSourceType);
+            var loadedDiagnosticSourceAssemblyFileVersionAttribute = loadedDiagnosticSourceAssembly?.GetCustomAttribute<AssemblyFileVersionAttribute>();
+            var versionString = loadedDiagnosticSourceAssemblyFileVersionAttribute?.Version;
+            if (versionString != null)
+            {
+                return new Version(versionString);
+            }
+        }
+
+        return null;
+    }
+
+    protected virtual Version? GetVersionFromAutoInstrumentation()
+    {
+        var autoInstrumentationDiagnosticSourceLocation = Path.Combine(StartupHook.LoaderAssemblyLocation ?? string.Empty, "System.Diagnostics.DiagnosticSource.dll");
+        var autoInstrumentationDiagnosticSourceFileVersionInfo = FileVersionInfo.GetVersionInfo(autoInstrumentationDiagnosticSourceLocation);
+        var autoInstrumentationDiagnosticSourceFileVersion = new Version(autoInstrumentationDiagnosticSourceFileVersionInfo.FileVersion);
+        return autoInstrumentationDiagnosticSourceFileVersion;
+    }
 }

test/OpenTelemetry.AutoInstrumentation.StartupHook.Tests/DiagnosticSourceRuleTests.cs

@@ -0,0 +1,79 @@
+// <copyright file="DiagnosticSourceRuleTests.cs" company="OpenTelemetry Authors">
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// </copyright>
+
+using OpenTelemetry.AutoInstrumentation.Logging;
+using OpenTelemetry.AutoInstrumentation.RulesEngine;
+using Xunit;
+
+namespace OpenTelemetry.AutoInstrumentation.StartupHook.Tests;
+public class DiagnosticSourceRuleTests
+{
+#pragma warning disable CS8625 // Cannot convert null literal to non-nullable reference type.
+    public static IEnumerable<object[]> RuleTestData =>
+       new List<object[]>
+       {
+                new object[] { "6.0.0.0", "7.0.0.0", "Rule Engine: Application has direct or indirect reference to older version of System.Diagnostics.DiagnosticSource.dll 6.0.0.0.", false },
+                new object[] { "8.0.0.0", "7.0.0.0", "Rule Engine: DiagnosticSourceRule evaluation success.", true },
+                new object[] { "7.0.0.0", "7.0.0.0", "Rule Engine: DiagnosticSourceRule evaluation success.", true },
+                new object[] { null, "7.0.0.0", "Rule Engine: DiagnosticSourceRule evaluation success.", true },
+                new object[] { "7.0.0.0", null, "Rule Engine: DiagnosticSourceRule evaluation success.", true },
+                new object[] { null, null, "Rule Engine: DiagnosticSourceRule evaluation success.", true },
+       };
+#pragma warning restore CS8625 // Cannot convert null literal to non-nullable reference type.
+
+    [Theory]
+    [MemberData(nameof(RuleTestData))]
+    public void DiagnosticSourceVersion(string appVersion, string autoInstrumentationVersion, string logMessage, bool result)
+    {
+        var logger = new TestLogger();
+        var rule = new TestableDiagnosticSourceRule(appVersion, autoInstrumentationVersion, logger);
+        Assert.Equal(result, rule.Evaluate());
+        Assert.Equal(logMessage, logger.LogRecords[0].Message);
+    }
+}
+
+internal class TestableDiagnosticSourceRule : DiagnosticSourceRule
+{
+    private readonly string appVersion;
+    private readonly string autoInstrumentationVersion;
+
+    public TestableDiagnosticSourceRule(string appVersion, string autoInstrumentationVersion, IOtelLogger otelLogger)
+        : base(otelLogger)
+    {
+        this.appVersion = appVersion;
+        this.autoInstrumentationVersion = autoInstrumentationVersion;
+    }
+
+    protected override Version? GetVersionFromApp()
+    {
+        if (appVersion == null)
+        {
+            return null;
+        }
+
+        return new Version(appVersion);
+    }
+
+    protected override Version? GetVersionFromAutoInstrumentation()
+    {
+        if (autoInstrumentationVersion == null)
+        {
+            return null;
+        }
+
+        return new Version(autoInstrumentationVersion);
+    }
+}