Secure IP Address Filtering

[Muiris Woulfe (muiriswoulfe)]

Purpose

Prevent clients from bypassing IP-based feature controls through untrusted forwarding data.

Impact

IP-gated features now rely on trusted connection information. Updated guidance and regression coverage reduce the risk of reintroducing the bypass.

[Copilot]

Pull request overview

This PR hardens the Feature Management IP address filter to prevent bypass via untrusted forwarding headers by relying only on trusted connection metadata (the remote address as determined by the hosting stack / forwarded headers middleware).

Changes:

• Update IPAddressFilter to evaluate feature gating using only HttpContext.Connection.RemoteIpAddress (no X-Forwarded-For parsing and no “local request” bypass).
• Remove forwarded-IP parsing helpers from HttpContextExtensions and the X-Forwarded-For header constant from RequestParameters.
• Refresh unit tests and documentation to reflect the trusted-proxy / ForwardedHeadersMiddleware requirement.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
tests/FeatureManagement.UnitTests/Filters/IPAddressFilterTests.cs	Updates coverage to ensure forwarded headers are ignored and only RemoteIpAddress drives evaluation.
tests/FeatureManagement.UnitTests/Extensions/HttpContextExtensionsTests.cs	Removes tests for deleted forwarded-IP and local-request helpers.
src/FeatureManagement/README.md	Documents the trusted-proxy requirement and clarifies RemoteIpAddress behavior.
src/FeatureManagement/Filters/IPAddressFilter.cs	Switches filter evaluation to trusted RemoteIpAddress only.
src/FeatureManagement/Extensions/HttpContextExtensions.cs	Removes forwarded-IP parsing and IsLocal logic now out of scope.
src/FeatureManagement/Constants/RequestParameters.cs	Drops the X-Forwarded-For header constant.
.github/copilot-instructions.md	Adds repo guidance to avoid X-Forwarded-For parsing and local bypass in IPAddressFilter.

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[Copilot]

Pull request overview

Copilot reviewed 7 out of 7 changed files in this pull request and generated no new comments.

[Copilot]

Pull request overview

Copilot reviewed 7 out of 7 changed files in this pull request and generated 1 comment.

Suppressed comments (2)

tests/FeatureManagement.UnitTests/Filters/IPAddressFilterTests.cs:297

• This test is meant to validate that spoofed X-Forwarded-For is ignored; using the framework constant for the header name helps ensure the test is actually setting the correct header (a typo would still pass otherwise).

		m_httpContext.Request.Headers["X-Forwarded-For"] = forwardedIp.ToString();

tests/FeatureManagement.UnitTests/Filters/IPAddressFilterTests.cs:410

• Using the framework constant for the X-Forwarded-For header name avoids tests passing due to an accidental misspelling (since the filter ignores the header either way) and keeps the test aligned with ASP.NET Core conventions.

		m_httpContext.Request.Headers["X-Forwarded-For"] = "10.1.1.1,203.0.113.10";

[Muiris Woulfe (muiriswoulfe)]

Replaced by #883, which contains the same commits on a branch hosted directly in microsoft/Omex.