feat: add BodyInspectionHandler

Closes microsoft#482

src/http/httpClient/Middleware/BodyInspectionHandler.cs

@@ -0,0 +1,95 @@
+// ------------------------------------------------------------------------------
+//  Copyright (c) Microsoft Corporation.  All Rights Reserved.  Licensed under the MIT License.  See License in the project root for license information.
+// ------------------------------------------------------------------------------
+
+using System;
+using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
+using System.IO;
+using System.Net.Http;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.Kiota.Http.HttpClientLibrary.Extensions;
+using Microsoft.Kiota.Http.HttpClientLibrary.Middleware.Options;
+
+namespace Microsoft.Kiota.Http.HttpClientLibrary.Middleware;
+
+/// <summary>
+/// The Body Inspection Handler allows the developer to inspect the body of the request and response.
+/// </summary>
+public class BodyInspectionHandler : DelegatingHandler
+{
+    private readonly BodyInspectionHandlerOption _defaultOptions;
+
+    /// <summary>
+    /// Create a new instance of <see cref="BodyInspectionHandler"/>
+    /// </summary>
+    /// <param name="defaultOptions">Default options to apply to the handler</param>
+    public BodyInspectionHandler(BodyInspectionHandlerOption? defaultOptions = null)
+    {
+        _defaultOptions = defaultOptions ?? new BodyInspectionHandlerOption();
+    }
+
+    /// <inheritdoc/>
+    protected override async Task<HttpResponseMessage> SendAsync(
+        HttpRequestMessage request,
+        CancellationToken cancellationToken
+    )
+    {
+        if (request == null)
+            throw new ArgumentNullException(nameof(request));
+
+        var options = request.GetRequestOption<BodyInspectionHandlerOption>() ?? _defaultOptions;
+
+        Activity? activity;
+        if (request.GetRequestOption<ObservabilityOptions>() is { } obsOptions)
+        {
+            var activitySource = ActivitySourceRegistry.DefaultInstance.GetOrCreateActivitySource(
+                obsOptions.TracerInstrumentationName
+            );
+            activity = activitySource?.StartActivity(
+                $"{nameof(RedirectHandler)}_{nameof(SendAsync)}"
+            );
+            activity?.SetTag("com.microsoft.kiota.handler.bodyInspection.enable", true);
+        }
+        else
+        {
+            activity = null;
+        }
+        try
+        {
+            if (options.InspectRequestBody)
+            {
+                options.RequestBody = await CopyToStreamAsync(request.Content);
+            }
+            var response = await base.SendAsync(request, cancellationToken).ConfigureAwait(false);
+            if (options.InspectResponseBody)
+            {
+                options.ResponseBody = await CopyToStreamAsync(response.Content);
+            }
+
+            return response;
+        }
+        finally
+        {
+            activity?.Dispose();
+        }
+
+#if NETSTANDARD2_1_OR_GREATER || NETCOREAPP3_0_OR_GREATER
+        [return: NotNullIfNotNull(nameof(httpContent))]
+#endif
+        static async Task<Stream?> CopyToStreamAsync(HttpContent? httpContent)
+        {
+            if (httpContent == null)
+            {
+                return null;
+            }
+
+            var stream = new MemoryStream();
+            await httpContent.CopyToAsync(stream);
+            stream.Position = 0;
+
+            return stream;
+        }
+    }
+}

src/http/httpClient/Middleware/Options/BodyInspectionHandlerOption.cs

@@ -0,0 +1,44 @@
+// ------------------------------------------------------------------------------
+//  Copyright (c) Microsoft Corporation.  All Rights Reserved.  Licensed under the MIT License.  See License in the project root for license information.
+// ------------------------------------------------------------------------------
+
+using System.IO;
+using Microsoft.Kiota.Abstractions;
+
+namespace Microsoft.Kiota.Http.HttpClientLibrary.Middleware.Options;
+
+/// <summary>
+/// The Body Inspection Option allows the developer to inspect the body of the request and response.
+/// </summary>
+public class BodyInspectionHandlerOption : IRequestOption
+{
+    /// <summary>
+    /// Gets or sets a value indicating whether the request body should be inspected.
+    /// Note tht this setting increases memory usae as the request body is copied to a new stream.
+    /// </summary>
+    public bool InspectRequestBody { get; set; }
+
+    /// <summary>
+    /// Gets or sets a value indicating whether the response body should be inspected.
+    /// Note tht this setting increases memory usae as the request body is copied to a new stream.
+    /// </summary>
+    public bool InspectResponseBody { get; set; }
+
+    /// <summary>
+    /// Gets the request body stream for the current request. This stream is available
+    /// only if InspectRequestBody is set to true and the request contains a body.
+    /// This stream is not disposed of by kiota, you need to take care of that.
+    /// Note that this stream is a copy of the original request body stream, which has
+    /// impact on memory usage. Use adequately.
+    /// </summary>
+    public Stream? RequestBody { get; internal set; }
+
+    /// <summary>
+    /// Gets the response body stream for the current request. This stream is available
+    /// only if InspectResponseBody is set to true.
+    /// This stream is not disposed of by kiota, you need to take care of that.
+    /// Note that this stream is a copy of the original request body stream, which has
+    /// impact on memory usage. Use adequately.
+    /// </summary>
+    public Stream? ResponseBody { get; internal set; }
+}

tests/http/httpClient/Middleware/BodyInspectionHandlerTests.cs

@@ -0,0 +1,112 @@
+using System.Net.Http;
+using Microsoft.Kiota.Http.HttpClientLibrary.Middleware;
+using Microsoft.Kiota.Http.HttpClientLibrary.Middleware.Options;
+using Microsoft.Kiota.Http.HttpClientLibrary.Tests.Mocks;
+using Xunit;
+
+namespace Microsoft.Kiota.Http.HttpClientLibrary.Tests.Middleware;
+
+public class BodyInspectionHandlerTests : IDisposable
+{
+    private readonly List<IDisposable> _disposables = [];
+
+    [Fact]
+    public void BodyInspectionHandlerConstruction()
+    {
+        using var defaultValue = new BodyInspectionHandler();
+        Assert.NotNull(defaultValue);
+    }
+
+    [Fact]
+    public async Task BodyInspectionHandlerGetsRequestBodyStream()
+    {
+        var option = new BodyInspectionHandlerOption { InspectRequestBody = true, };
+        using var invoker = GetMessageInvoker(new HttpResponseMessage(), option);
+
+        // When
+        var request = new HttpRequestMessage(HttpMethod.Post, "https://localhost")
+        {
+            Content = new StringContent("request test")
+        };
+        var response = await invoker.SendAsync(request, default);
+
+        // Then
+        Assert.NotNull(option.RequestBody);
+        Assert.Equal("request test", GetStringFromStream(option.RequestBody!));
+    }
+
+    [Fact]
+    public async Task BodyInspectionHandlerGetsNullRequestBodyStreamWhenThereIsNoRequestBody()
+    {
+        var option = new BodyInspectionHandlerOption { InspectRequestBody = true, };
+        using var invoker = GetMessageInvoker(new HttpResponseMessage(), option);
+
+        // When
+        var request = new HttpRequestMessage(HttpMethod.Get, "https://localhost");
+        var response = await invoker.SendAsync(request, default);
+
+        // Then
+        Assert.Null(option.RequestBody);
+    }
+
+    [Fact]
+    public async Task BodyInspectionHandlerGetsResponseBodyStream()
+    {
+        var option = new BodyInspectionHandlerOption { InspectResponseBody = true, };
+        using var invoker = GetMessageInvoker(CreateHttpResponseWithBody(), option);
+
+        // When
+        var request = new HttpRequestMessage(HttpMethod.Get, "https://localhost");
+        var response = await invoker.SendAsync(request, default);
+
+        // Then
+        Assert.NotNull(option.ResponseBody);
+        Assert.Equal("response test", GetStringFromStream(option.ResponseBody!));
+        Assert.Equal("response test", await response.Content.ReadAsStringAsync()); // response from option is separate from "normal" response stream
+    }
+
+    [Fact]
+    public async Task BodyInspectionHandlerGetsEmptyResponseBodyStreamWhenThereIsNoResponseBody()
+    {
+        var option = new BodyInspectionHandlerOption { InspectResponseBody = true, };
+        using var invoker = GetMessageInvoker(new HttpResponseMessage(), option);
+
+        // When
+        var request = new HttpRequestMessage(HttpMethod.Get, "https://localhost");
+        var response = await invoker.SendAsync(request, default);
+
+        // Then
+        Assert.NotNull(option.ResponseBody);
+        Assert.Equal(string.Empty, GetStringFromStream(option.ResponseBody!));
+    }
+
+    private static HttpResponseMessage CreateHttpResponseWithBody() =>
+        new() { Content = new StringContent("response test") };
+
+    private HttpMessageInvoker GetMessageInvoker(
+        HttpResponseMessage httpResponseMessage,
+        BodyInspectionHandlerOption option
+    )
+    {
+        var messageHandler = new MockRedirectHandler();
+        _disposables.Add(messageHandler);
+        _disposables.Add(httpResponseMessage);
+        messageHandler.SetHttpResponse(httpResponseMessage);
+        // Given
+        var handler = new BodyInspectionHandler(option) { InnerHandler = messageHandler };
+        _disposables.Add(handler);
+        return new HttpMessageInvoker(handler);
+    }
+
+    private static string GetStringFromStream(Stream stream)
+    {
+        using var reader = new StreamReader(stream);
+        return reader.ReadToEnd();
+    }
+
+    public void Dispose()
+    {
+        _disposables.ForEach(static x => x.Dispose());
+        GC.SuppressFinalize(this);
+    }
+}