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Prevent browser refresh script from injecting into iframes #21954

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Merged
merged 1 commit into from
Oct 11, 2021
Merged

Prevent browser refresh script from injecting into iframes #21954

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16 changes: 13 additions & 3 deletions src/BuiltInTools/BrowserRefresh/BrowserRefreshMiddleware.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,7 @@
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Http.Features;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Primitives;
using Microsoft.Net.Http.Headers;

namespace Microsoft.AspNetCore.Watch.BrowserRefresh
Expand All @@ -23,7 +24,7 @@ public BrowserRefreshMiddleware(RequestDelegate next, ILogger<BrowserRefreshMidd
public async Task InvokeAsync(HttpContext context)
{
// We only need to support this for requests that could be initiated by a browser.
if (IsBrowserRequest(context))
if (IsBrowserDocumentRequest(context))
{
// Use a custom StreamWrapper to rewrite output on Write/WriteAsync
using var responseStreamWrapper = new ResponseStreamWrapper(context, _logger);
Expand Down Expand Up @@ -57,16 +58,25 @@ public async Task InvokeAsync(HttpContext context)
}
}

internal static bool IsBrowserRequest(HttpContext context)
internal static bool IsBrowserDocumentRequest(HttpContext context)
{
var request = context.Request;
if (!HttpMethods.IsGet(request.Method) && !HttpMethods.IsPost(request.Method))
{
return false;
}

if (request.Headers.TryGetValue("Sec-Fetch-Dest", out var values) &&
!StringValues.IsNullOrEmpty(values) &&
!string.Equals(values[0], "document", StringComparison.OrdinalIgnoreCase))
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@SteveSandersonMS SteveSandersonMS Oct 11, 2021

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The spec doesn't talk about any other casing than document so strictly speaking I think this could be StringComparison.Ordinal. However I can't think of any real drawback to doing a case-insensitive check.

{
// See https://github.com/dotnet/aspnetcore/issues/37326.
// Only inject scripts that are destined for a browser page.
return false;
}

var typedHeaders = request.GetTypedHeaders();
if (!(typedHeaders.Accept is IList<MediaTypeHeaderValue> acceptHeaders))
if (typedHeaders.Accept is not IList<MediaTypeHeaderValue> acceptHeaders)
{
return false;
}
Expand Down
116 changes: 108 additions & 8 deletions src/Tests/Microsoft.AspNetCore.Watch.BrowserRefresh.Tests/BrowserRefreshMiddlewareTest.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -16,7 +16,7 @@ public class BrowserRefreshMiddlewareTest
[InlineData("DELETE")]
[InlineData("head")]
[InlineData("Put")]
public void IsBrowserRequest_ReturnsFalse_ForNonGetOrPostRequests(string method)
public void IsBrowserDocumentRequest_ReturnsFalse_ForNonGetOrPostRequests(string method)
{
// Arrange
var context = new DefaultHttpContext
Expand All @@ -32,14 +32,14 @@ public void IsBrowserRequest_ReturnsFalse_ForNonGetOrPostRequests(string method)
};

// Act
var result = BrowserRefreshMiddleware.IsBrowserRequest(context);
var result = BrowserRefreshMiddleware.IsBrowserDocumentRequest(context);

// Assert
Assert.False(result);
}

[Fact]
public void IsBrowserRequest_ReturnsFalse_IsRequestDoesNotAcceptHtml()
public void IsBrowserDocumentRequest_ReturnsFalse_IsRequestDoesNotAcceptHtml()
{
// Arrange
var context = new DefaultHttpContext
Expand All @@ -55,14 +55,14 @@ public void IsBrowserRequest_ReturnsFalse_IsRequestDoesNotAcceptHtml()
};

// Act
var result = BrowserRefreshMiddleware.IsBrowserRequest(context);
var result = BrowserRefreshMiddleware.IsBrowserDocumentRequest(context);

// Assert
Assert.False(result);
}

[Fact]
public void IsBrowserRequest_ReturnsTrue_ForGetRequestsThatAcceptHtml()
public void IsBrowserDocumentRequest_ReturnsTrue_ForGetRequestsThatAcceptHtml()
{
// Arrange
var context = new DefaultHttpContext
Expand All @@ -78,14 +78,14 @@ public void IsBrowserRequest_ReturnsTrue_ForGetRequestsThatAcceptHtml()
};

// Act
var result = BrowserRefreshMiddleware.IsBrowserRequest(context);
var result = BrowserRefreshMiddleware.IsBrowserDocumentRequest(context);

// Assert
Assert.True(result);
}

[Fact]
public void IsBrowserRequest_ReturnsTrue_ForRequestsThatAcceptAnyHtml()
public void IsBrowserDocumentRequest_ReturnsTrue_ForRequestsThatAcceptAnyHtml()
{
// Arrange
var context = new DefaultHttpContext
Expand All @@ -101,12 +101,112 @@ public void IsBrowserRequest_ReturnsTrue_ForRequestsThatAcceptAnyHtml()
};

// Act
var result = BrowserRefreshMiddleware.IsBrowserRequest(context);
var result = BrowserRefreshMiddleware.IsBrowserDocumentRequest(context);

// Assert
Assert.True(result);
}

[Fact]
public void IsBrowserDocumentRequest_ReturnsTrue_IfRequestDoesNotHaveFetchMetadataRequestHeader()
{
// Arrange
var context = new DefaultHttpContext
{
Request =
{
Method = "GET",
Headers =
{
["Accept"] = "text/html",
},
},
};

// Act
var result = BrowserRefreshMiddleware.IsBrowserDocumentRequest(context);

// Assert
Assert.True(result);
}

[Fact]
public void IsBrowserDocumentRequest_ReturnsTrue_IfRequestFetchMetadataRequestHeaderIsEmpty()
{
// Arrange
var context = new DefaultHttpContext
{
Request =
{
Method = "Post",
Headers =
{
["Accept"] = "text/html",
["Sec-Fetch-Dest"] = string.Empty,
},
},
};

// Act
var result = BrowserRefreshMiddleware.IsBrowserDocumentRequest(context);

// Assert
Assert.True(result);
}

[Theory]
[InlineData("document")]
[InlineData("Document")]
public void IsBrowserDocumentRequest_ReturnsTrue_IfRequestFetchMetadataRequestHeaderIsDocument(string headerValue)
{
// Arrange
var context = new DefaultHttpContext
{
Request =
{
Method = "Post",
Headers =
{
["Accept"] = "text/html",
["Sec-Fetch-Dest"] = headerValue,
},
},
};

// Act
var result = BrowserRefreshMiddleware.IsBrowserDocumentRequest(context);

// Assert
Assert.True(result);
}

[Theory]
[InlineData("frame")]
[InlineData("iframe")]
[InlineData("serviceworker")]
public void IsBrowserDocumentRequest_ReturnsFalse_IfRequestFetchMetadataRequestHeaderIsNotDocument(string headerValue)
{
// Arrange
var context = new DefaultHttpContext
{
Request =
{
Method = "Post",
Headers =
{
["Accept"] = "text/html",
["Sec-Fetch-Dest"] = headerValue,
},
},
};

// Act
var result = BrowserRefreshMiddleware.IsBrowserDocumentRequest(context);

// Assert
Assert.False(result);
}

[Fact]
public async Task InvokeAsync_AddsScriptToThePage()
{
Expand Down